Patent Publication Number: US-2010114499-A1

Title: System and method for processing raw activity energy expenditure data

Description:
TECHNICAL FIELD OF THE INVENTION 
     This invention relates in general to an activity monitor and, more particularly, to a system and a method for processing raw activity energy expenditure data. 
     BACKGROUND OF THE INVENTION 
     An activity monitor allows the measurement of human energy expenditure. The activity monitor allows the user wearing the activity monitor to measure the amount of energy consumed during a selected period of time for a certain physical activity, such as walking and running. An activity monitor utilizing a single accelerometer is less expensive and consumes less power than an activity monitor utilizing a plurality of accelerometers. A single accelerometer may be a uni-axial accelerometer that generates a signal, which is proportional to the energy expenditure, such that the signal is generated in response to body movements in the particular direction along the single axis of the accelerometer. 
     When user is performing a low intensity physical activity, such as walking, the dominant direction of body movement is the up and down direction occurring along the vertical axis. If the accelerometer is properly aligned with the body movement of user to measure movements along the vertical axis, the activity monitor will provide a signal, which is a relatively accurate representation of the energy expenditure by the user. However, when user is performing a high intensity physical activity, such as running, the forward and backward movement of the body provides an additional, non-negligible contribution to energy expended by the user. In response to the backward and forward movement occurring along the horizontal axis during high intensity physical activity, the accelerometer will provide a signal, which is an inaccurate representation of the actual energy expenditure by the user because the accelerometer primarily measures movements along the vertical axis. Therefore, the energy expenditure measured by the uni-axial accelerometer in the activity monitor will deviate from the real energy expenditure of the user. One way to solve this problem for accurately measuring energy expended requires using an additional accelerometer, which can measure forward and backward body movement along the horizontal axis. However, this additional sensor will increase the cost of the activity monitor, and the amount of power consumed by the activity monitor. 
     Additionally, an activity monitor with only one sensor, such as a uni-axial accelerometer, does not include hardware operable to calculate the speed of a user while the user is walking or running. One way to solve this problem for determining the speed of the user requires using an additional sensor for tracking speed, such as an accelerometer worn on the foot or shoe, a switch on the sole of the shoe, or a GPS sensor. However, this additional sensor will increase the cost of the activity monitor, and the amount of power consumed by the activity monitor. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a method, a system, and an apparatus for collecting, converting, displaying, and communicating data is provided, which substantially eliminates or reduces the disadvantages and problems associated with previous systems, methods, and apparatuses. 
     According to one embodiment, a method is provided for calculating, by an activity monitor comprising one accelerometer, a raw activity energy expenditure data based on movement by a user. The method includes determining if the raw activity energy expenditure data is associated with a high intensity physical activity, wherein the high intensity physical activity causes the raw activity energy expenditure data to differ from an expected activity energy expenditure data. The method includes calculating a corrected activity energy expenditure data, if the raw activity energy expenditure data is associated with the high intensity physical activity, based on the raw activity energy expenditure data, wherein the corrected activity energy expenditure data is substantially identical to the expected activity energy expenditure data. The method may display the corrected activity energy expenditure data. the corrected activity energy expenditure data in METs is calculated by (RawAEE_MET−T)*B+F, wherein RawAEE_MET is the raw activity energy expenditure data, wherein T is a predetermined threshold value associated with the high intensity physical activity, wherein B is a predetermined gradient value, wherein F is a predetermined offset value. 
     According to one embodiment, a method is provided for determining a speed of the user based on the corrected activity energy expenditure data and displaying the speed of the user. The speed of the user may be determined by (CorAEE_MET−1)/G, wherein CorAEE_MET is the corrected activity energy expenditure data in metabolic equivalents (METs), wherein 1 is one MET, wherein G is a predetermined gradient value of 0.95 hours/kilometers (h/km) during high intensity physical activity, such as running, or 0.49 h/km during light intensity physical activity, such as walking. 
     Important technical advantages of certain embodiments of the present invention include utilizing a single uni-axial accelerometer to accurately calculate activity energy expended by user during both low intensity and high intensity activities. As a result of only requiring a single accelerometer to accurately measure activity energy expended by user, the activity monitor is less expensive and consumes less power than activity monitors with additional sensors for accomplishing this task. 
     Other technical advantages of certain embodiments of the present invention include utilizing a single uni-axial accelerometer to calculate speed of user during both low intensity and high intensity activities. As a result of only requiring a single accelerometer to accurately measure speed of user, activity monitor is less expensive and consumes less power than an activity monitor with additional sensors for accomplishing this task. Prior solutions may utilize the global position system (GPS), but the GPS requires high-energy consumption of activity monitor, which requires the user to frequently charge or replace batteries used by activity monitor. 
     Other technical advantages of certain embodiments of the present invention include utilizing a single uni-axial accelerometer to obtain continuous display of speed and distance without requiring a sensor attached to the user&#39;s foot. Prior solutions included attaching one or more sensors to the foot or shoe of the user, such that the sensors monitor the acceleration of the foot. The data may be single or double integrated to obtain speed and distance information of the step. The sensors may monitor the time the foot is on the ground compared to in the air, from which an estimate can be made of walking or running speed. One advantage of the present invention is that no special attachment to the shoe is necessary to obtain continuous read-out of speed and distance. 
     Other technical advantages of the present invention will be readily apparent to one skilled in the art from the following figures, descriptions, and claims. Moreover, while specific advantages have been enumerated above, various embodiments may include all, some, or none of the enumerated advantages. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To provide a more complete understanding of the present invention and features and advantages thereof, reference is made to the following description, taken in conjunction with the accompanying figures, wherein like reference numerals represent like parts, in which: 
         FIG. 1  is a simplified block diagram that illustrates a system in accordance with a particular embodiment of the present invention; 
         FIG. 2  is a simplified block diagram that illustrates an activity monitor apparatus used in the system in accordance with a particular embodiment of the present invention; 
         FIG. 3  is a simplified block diagram that illustrates an activity monitor generating signals in response to a user&#39;s movement; 
         FIG. 4A  is a graph illustrating an example equation for calculating the expected activity energy expended data in METs; 
         FIG. 4B  is a graph illustrating step one of an example equation for calculating the corrected activity energy expended data in METs; 
         FIG. 4C  is a graph illustrating step two of an example equation for calculating the corrected activity energy expended data in METs; 
         FIG. 4D  is a graph illustrating step three of an example equation for calculating the corrected activity energy expended data in METs; 
         FIG. 4E  is a graph illustrating an example equation for calculating the speed of a user based on METs expended; and 
         FIG. 5  is a flowchart that illustrates an example method of correction element and speed element in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS 
       FIG. 1  is a simplified block diagram that illustrates a system in accordance with a particular embodiment of the present invention. System  10  includes a communication network  18 , a user  12 , one or more computer devices  16 , an activity monitor  14 , one or more servers  32 , one or more databases  34 , and a web portal  40 . Activity monitor  14  may include a correction element and a speed element  56 . Other architectures and components of system  10 , including various architectures and components of activity monitor  14 , may be used without departing from the scope of this disclosure. 
     In general, users  12  may wear an activity monitor  14  to track one or more activity data metrics associated with an activity. Activity data may include the calories burned, metabolic equivalents (METS) expended, physical activity monitor (PAM) points spent (where PAM points may be defined as activity induced energy expenditure divided by the basal metabolic rate multiplied by 100), minutes in light activity zone, minutes in medium activity zone, minutes in high activity zone, current speed, distance traveled, etcetera. Users  12  may couple activity monitor to one or more computer devices  16 , which provide users access to a web portal  40 . Activity monitor  14  may transmit data to web portal  40 . Web portal  40  may utilize activity data to provide user  12  with feedback or goals in response to the activity data. 
     In one particular embodiment, activity monitor  14  may use calories as the activity data metric to calculate the raw activity energy expenditure data (RawAEE) by user  12 . In this embodiment, the equation used by activity monitor  14  for determining the raw calories expended by user  12  may be: 
       RawAEE_Cal=( c*|a| )*BMR 
     The variable |a| used by RawAEE_Cal is a value determined by activity monitor  14  based on signals generated by accelerometer in response to activity by user  12 . The variable |a| may refer to the average of the absolute value of acceleration data over a particular time period. Determining the value of |a| is explained in more detail below in  FIG. 3 . The constants, c and BMR, used by RawAEE_Cal may be a predetermined value stored in activity monitor  14 . These predetermined values associated with the constants may be stored in activity monitor  14  during the manufacture process of activity monitor  14 , by downloading new software for activity monitor  14 , or any other suitable way. The constant c may be a predetermined value used to multiply against |a| to produce an expected value. The constant BMR refers to the basal metabolic rate. The BMR is the amount of energy, such as calories, that user  12  consumes at rest. 
     In one particular embodiment, activity monitor  14  may use METs as the activity data metric to calculate the raw activity energy expenditure data (RawAEE_MET) by user  12 . In this embodiment, the equation used by activity monitor  14  for determining the raw METs expended by user  12  may be: 
       RawAEE_MET=( c*|a| )+1 
     The variable |a| used by RawAEE_MET is a value determined by activity monitor  14  based on signals generated by accelerometer in response to activity by user  12 . The variable |a| may refer to the average of the absolute value of acceleration data over a particular time period. Determining the value of |a| is explained in more detail below in  FIG. 3 . The constants, c and 1, used by RawAEE_MET may be a predetermined value stored in activity monitor  14 . These predetermined values associated with the constants may be stored in activity monitor  14  during the manufacture process of activity monitor  14 , by downloading new software for activity monitor  14 , or any other suitable way. The constant c may be a predetermined value used to multiply against |a| to produce an expected value. For example, the constant c may be a value determined by the amplification factor of the amplifier electronics of activity monitor  14  in addition to the type of analog to digital converter used by activity monitor  14 . The constant  1  refers to one MET. 
     In one particular embodiment, activity monitor  14  may use PAM points as the activity data metric to calculate the raw activity energy expenditure data (RawAEE_PAM) by user  12 . In this embodiment, the equation used by activity monitor  14  for determining the raw PAM points expended by user  12  may be: 
       RawAEE_PAM= c*|a|   
     The variable |a| used by RawAEE_PAM is a value determined by activity monitor  14  based on signals generated by accelerometer in response to activity by user  12 . The variable |a| may refer to the average of the absolute value of acceleration data over a particular time period. Determining the value of |a| is explained in more detail below in  FIG. 3 . The constant c used by RawAEE_PAM may be a predetermined value stored in activity monitor  14 . These predetermined values associated with the constants may be stored in activity monitor  14  during the manufacture process of activity monitor  14 , by downloading new software for activity monitor  14 , or any other suitable way. The constant c may be a predetermined value used to multiply against |a| to produce an expected value. In alternative embodiments, PAM points may be defined differently such that RawAEE_PAM may utilize a different equation for determining the raw PAM points expended by user  12 . Additionally, other alternative embodiments may utilize other activity data metrics for determining the raw activity data of energy expended by user  12 . 
     It is important to mention that activity monitor  14  is operable to determine the energy expended for one or more activity data metrics without requiring user  12  to enter any personal information. For example, METs and PAM points are substantially independent of body weight. Therefore, METs and PAM points can express activity energy expended by user  12  without knowledge of user&#39;s personal information, such as gender, age, height, or weight. As a result, activity monitor  14  may be operable to provide activity data in METs and PAM points without requiring user  12  to input any personal information. Activity monitor  14  may store the necessary equations and data for calculating the energy expended in activity monitor  14  during the manufacture process of activity monitor  14 , by downloading new software for activity monitor  14 , or any other suitable way. 
     It is also important to mention that activity monitor  14  is operable to determine the speed of user  12  without requiring user  12  to enter any personal information. User&#39;s speed may be a direct relationship to the METs or PAM points expended by user  12 . Activity monitor  14  may store the necessary equations and data for determining the speed of user in activity monitor  14  during the manufacture process of activity monitor  14 , by downloading new software for activity monitor  14 , or any other suitable way. The speed element  56  calculates the speed of user  12 , and this is discussed in more detail below. 
     In one embodiment, activity monitor  14  may also measure the time spent by user  12  in the light, medium, and high activity zones. Literature or information available on web portal  40  may instruct users  12  how much time should be spent in each activity zone. The light activity zone may be associated with energy expended by user  12  while fidgeting, i.e., not a sedentary state, but also not walking at a brisk pace or activity with similar intensity. For example, data indicating speed of less than four kilometers per hour (km/h) but more than one km/h or activity energy expended data representing more than two METs but less than four METs may be associated with the light activity zone. The medium activity zone may be associated with energy expended by user  12  during low intensity physical activity, such as walking. For example, data indicating speed greater than four km/h and less than eight km/h or activity energy expended data greater than three METs and less than seven METs may be associated with the medium activity zone. The high activity zone may be associated with energy expended by user during high intensity physical activity, such as running. For example, data indicating speed of greater than eight km/h or activity energy expended data greater than seven METs may be associated with the high activity zone. The light activity zone may be referred to as the life activity zone, the medium activity zone may be referred to as the health activity zone, and the high activity zone may be referred to as the sports zone. In alternative embodiments, the activity zones may utilize different threshold values. In another embodiment, the activity zones may utilize different activity data metrics, such as PAM points. 
     In accordance with the teachings of the present invention, system  10  achieves an effective way for activity monitor  14  to correct raw activity energy expended data when user  12  is engaged in high intensity physical activity, such as running. System  10  also achieves an effective way for activity monitor  14  to determine speed of user  12  based on the corrected activity energy expended data. Activity monitor  14  comprising a single accelerometer may produce signals proportional to energy expenditure of user  12 . The single accelerometer may produce signals associated with the up and down (vertical) axis, such that signals are generated in response to user&#39;s body movement in the up and down (vertical) axis. 
     During physical activities requiring low intensity, such as walking, activity monitor  14  may process these signals to a raw activity data metric, such that this activity data metric may represent an accurate value of the actual energy expended by user  12 . This raw activity energy expended data may be accurate while user  12  is walking because the dominant direction of user&#39;s body movement is in the up and down direction occurring along the vertical axis. However, during physical activities requiring high intensity, such as running, activity monitor  14  may process these signals to a raw activity energy expended data metric, such that this raw activity energy expended data may represent an inaccurate value of the actual energy expended by user  12 . This raw activity energy expended data may be inaccurate because user  12  expends additional energy with forward and backward (horizontal) movement of user&#39;s body during high intensity activity, such as running. 
     The single accelerometer associated with recording movement along the vertical axis may not be able to produce accurate signals associated with user&#39;s body movement in the backward and forward direction occurring along the horizontal axis. Correction element  55  may receive the raw activity energy expended data and, if needed, convert the raw activity energy expended data to a corrected activity energy expended data, such that the corrected activity energy expended data represents an accurate value of the actual energy expended by user  12 . This corrected activity energy expended data includes energy expended by user  12  in both the horizontal axis and the vertical axis. 
     Speed element  56  may receive the corrected activity energy expended data to determine the speed of user  12  during high intensity activity. Speed element  56  may use the raw activity energy expended data to determine speed of user  12  during low intensity activity. As a result, activity monitor  14  comprising a single accelerometer may be operable to display the accurate activity energy expended data and the accurate speed of user  12  during both low and high intensity physical activity. 
     Communication network  18  couples and facilitates wireless or wire line communication between computer devices  16 , activity monitors  14 , and servers  32 . Communication network  18  may, for example, communicate Internet Protocol (IP) packets, Frame Relay frames, Asynchronous Transfer Mode (ATM) cells, voice, video, data, and other suitable information between network addresses. Communication network  18  may also communicate data via wireless communications, such as by Wireless Application Protocol (WAP) standard protocols, including 802.11, third-generation (3G) protocols (such as W-CDMA or CDMA 2000, for example), Bluetooth, or Global System for Mobile Communications (GSM) protocols, for example. Communication network  18  may include one or more local area networks (LANs), radio access networks (RANs), metropolitan area networks (MANs), wide area networks (WANs), interactive television networks, all or a portion of the global computer network known as the Internet, and/or any other communication system or systems at one or more locations. 
     User  12  may include any individual desiring to use activity monitor  14 . User  12  may wear activity monitor  14  and couple activity monitor  14  to one or more computer devices  16  to connect to web portal  40 . Users  12  may engage in sedentary activity, low intensity activity, or high intensity activity while wearing activity monitor. User  12  may wear activity monitor  14  for an entire day or only for an event for a specified period of time. In one particular embodiment, users  12  may include physical education students who couple their activity monitors  14  to computer device  16  to transmit the data from activity monitor  14  to web portal  40 . Web Portal  40  allows teachers to view the physical activity data of their students and use this information to grade the students according to the curriculum. 
     Activity monitor  14  is generally operable to measure body movement of user  12 . In one embodiment, activity monitor  14  may also store data, receive data, convert data, display data, and transmit data for a multitude of purposes. In one embodiment, activity monitor  14  may comprise a single accelerometer, such that this single accelerometer may measure the user&#39;s up and down movement occurring on the vertical axis. Activity monitor  14  may only utilize one activity data metric or activity monitor may utilize a plurality of activity data metrics. 
     For example, based on signals associated with user&#39;s body movement, activity monitor  14  may measure one or more activity data metrics that may include calories, distances, PAM points, METs, speed, life zone minutes, health zone minutes, or sports zone minutes. Memory in activity monitor  14  may include volatile or non-volatile memory including, without limitation, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), removable media, or any other suitable local or remote memory component. In general, the memory may store various data including activity data metrics, equations and constant values associated with the equations, a user&#39;s account information, a user&#39;s goals, etcetera. For example, user&#39;s account information may include a unique identification number associated with each user  12 . Activity monitor  14  may be operable to receive data from web portal  40 , computer device  16 , machine, or any other device. Activity monitor  14  may further operable to transmit data to web portal  40  or computer device  16 . Activity monitor  14  may include a graphics card to display streaming video and data stored in memory. Activity monitor  14  may include a processor to convert signals from accelerometer and utilize equations for performing calculations. For example, activity monitor  14  may utilize equations from correction element  55  and/or speed element  56  to determine the actual energy expended by user and the actual speed of user  12 . Activity monitor  14  may be operable to receive software updates from server  32 . Additional details of activity monitor  14  are listed below in  FIG. 2 . 
     Software and/or hardware may reside in activity monitor  14  in order to achieve the teachings of collecting data, converting data, displaying data, and communicating data of the present invention. However, due to their flexibility, activity monitor  14  may alternatively be equipped with (or include) any suitable component, device, application specific integrated circuit (ASIC), processor, microprocessor, algorithm, read-only memory (ROM) element, random access memory (RAM) element, erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), field-programmable gate array (FPGA), or any other suitable element or object that is operable to facilitate the operations thereof. Considerable flexibility is provided by the structure of activity monitor  14  in the context of system  10  and, accordingly, it should be construed as such. 
     Correction element  55  may represent any suitable combination of hardware, software, and/or controlling logic operable to receive raw activity energy expended data and process the raw activity energy expended data to determine the corrected activity energy expended data, such that the corrected activity energy expended data represents the actual energy expended by user  12 . As explained above, activity monitor  14  may comprise a single uni-axial accelerometer that calculates raw activity energy expended data while user  12  is engaged in high intensity physical activity, such that this raw activity energy expended data represents an inaccurate amount of energy expended by user  12  since the backward and forward movement occurring on the horizontal axis may not be accurately measured by the uni-axial accelerometer measuring the up and down movement occurring on the vertical axis. Correction element  55  may correct the inaccurate raw activity energy expended data, such that the corrected activity energy expended data represents the actual energy expended by user  12  while engaged in high intensity physical activity. As a result, correction element  55  or any suitable component of activity monitor  14  may determine to only correct the raw activity energy expenditure data if the raw activity energy expenditure data is greater than a predetermined threshold value representing the value when the raw activity energy expenditure data begins to become inaccurate as a result of the high intensity physical activity. 
     In one embodiment, correction element  55  may utilize an equation to determine the corrected activity energy expenditure data (CorAEE). The equation utilized by correction element  55  may be based on the expected activity energy expenditure data (ExpAEE). The expected activity energy expenditure data for a particular activity data metric may be determined by a formula that expresses a relationship between the actual energy expended during low intensity physical activity, such as walking, and the actual energy expended during high intensity physical activity, such as running. The equation for the expected activity energy expenditure data in METs is illustrated below in  FIG. 4A . 
     For example, the equation for calculating the expected activity energy expenditure data using the MET as the physical activity metric may be a function of low intensity physical activity, such as walking, and a function of high intensity physical activity, such as running, as published by the American College of Sports Medicine (Ainsworth et al., Compendium of physical activities: An update of activity codes and MET intensities, Med. Sci. Sports. Exerc. 2000, S498-S516). This equation for calculating the expected activity energy expenditure data in METs may be: 
       ExpAEE_MET=( G*v )+1 
     The variable v used to calculate ExpAEE_MET is the velocity of user  12  in terms of km/h. The constant G is 0.49 h/km for low intensity physical activity, such as walking, that occurs while the velocity of user  12  is less than eight km/h. The constant G is 0.95 h/km for high intensity physical activity, such as running, that occurs while the velocity of user  12  is greater than eight km/h. The constant G represents the gradient, such that activity energy expended increases at a gradient of 0.95 h/km during high intensity physical activity and a gradient of 0.49 h/km during low intensity physical activity. The constant  1  refers to one MET. This equation for the expected activity energy expenditure data in METs is illustrated below in  FIG. 4A . 
     The equation for determining the corrected activity energy expenditure data in METs may be determined by referencing the equation of the expected activity energy expenditure data in METs. Correction element  55  or any suitable component of activity monitor  14  may determine to only utilize this equation to correct the raw activity energy expenditure data if the raw activity energy expenditure data is greater than a predetermined threshold value representing the value when the raw activity energy expenditure data begins to become inaccurate as a result of the high intensity physical activity. 
     This equation for calculating the corrected activity energy expenditure in METs may be: 
       CorAEE_MET=(RawAEE_MET− T )* B+F    
     The variable RawAEE_MET used in this equation is the value determined by activity monitor  14  in a previous calculation described above for calculating the raw METs expended by user  12 . The constants, T, B, and F, are all associated with determining the corrected activity energy expenditure in METs. The constants, T, B, and F, may be a predetermined value stored in activity monitor  14 . These predetermined values associated with the constants may be stored in activity monitor  14  during the manufacture process of activity monitor, by downloading new software for activity monitor, or any other suitable way. 
     The constant T may be a predetermined value representing a threshold value associated with high intensity physical activity, such that the threshold value is a value from the raw activity energy expended as calculated by activity monitor  14  based on signals from the single uni-axial accelerometer. All raw activity energy expended data above threshold value, T, may be associated with high intensity physical activity, such as running. For example, the threshold value associated with high intensity physical activity, such as running, may be all raw values greater than seven METs. This constant T may be the threshold value used to determine when correction element  55  should be utilized to correct raw activity energy expended data. 
     The constant B may be a predetermined value representing the gradient of the corrected activity energy expenditure data in METs. For example, B may be the quotient of the gradient G of the expected raw activity energy expenditure data in METs divided by the gradient of the raw activity energy expenditure data in METs. The constant F may be a predetermined value representing the offset value to apply to this equation, such that the offset value results in the corrected activity energy expenditure data in METs to essentially map the expected activity energy expenditure data in METs. The steps for calculating the corrected activity energy expenditure data in METs (CorAEE_MET) are explained in more detail below in  FIGS. 4A-4D . 
     In one embodiment, correction element  55  may determine to utilize the equation for determining the corrected activity energy expenditure data for only the raw activity energy expenditure data associated with high intensity physical activity, such as running. For example, when the MET is used as the physical activity metric, correction element  55  may determine to only utilize the equation for determining the corrected activity energy expenditure data for raw activity energy expenditure data greater than the threshold constant T. The threshold constant T is used as the determinant because this is the threshold value where the uni-axial accelerometer begins to generate inaccurate raw activity energy expended data because of high intensity physical activity. As a result of applying the equation for determining the corrected activity energy expenditure data, activity monitor  14  comprising a single uni-axial accelerometer may be operable to display an accurate activity energy expended data during both low and high intensity physical activity. 
     In alternative embodiments, other physical activity metrics, such as PAM points, may have their own equations for expected activity energy expended data and corrected activity energy expended data. Correction element  55  may apply the different equations for calculating the corrected activity energy expended data similarly to the MET, such that the equation may comprise a variable of the raw activity energy expended data, such as RawAEE_PAM, and one or more predetermined constants associated with the particular physical activity metric. 
     Speed element  56  may represent any suitable combination of hardware, software, and/or controlling logic operable to receive the raw activity energy expended data and/or the corrected activity energy expended data. Speed element may use this received data in its speed equation for determining the speed of user  12  during physical activity. Speed equation may calculate speed of user  12  by taking the inverse of the expected activity energy expected equation, such that the energy expended by user  12  is directly related to the velocity of user  12 . The relationship between expected activity energy expended data and speed of user  12  is illustrated below in  FIG. 4E . 
     In one embodiment, speed element  56  may determine to use the raw activity energy expended data in the speed equation to determine speed of user  12  during low intensity activity. In one embodiment, speed element  56  may determine to use the corrected activity energy expended data in the speed equation to determine speed of user  12  during high intensity activity. For example, when the MET is used as the physical activity metric, speed element  56  may determine to use the corrected activity energy expended data in the speed equation if the raw activity energy expenditure data is greater than the threshold constant T. If the raw activity energy expenditure data in METs is less than threshold constant T, speed element  56  may determine to use the raw activity energy expended data in the speed equation. As a result, activity monitor  14  comprising a single uni-axial accelerometer may be operable to display an accurate speed of user  12  during both low and high intensity physical activity. Additionally, speed element  56  allows activity monitor to display speed of user without requiring user to input any personal information, such as height or weight. 
     For example, the equation for calculating the speed of user  12  utilizing the MET as the physical activity metric may be a function of low intensity physical activity, such as walking, and a function of high intensity physical activity, such as running, as published by the American College of Sports Medicine (Ainsworth et al., Compendium of physical activities: An update of activity codes and MET intensities, Med. Sci. Sports. Exerc. 2000, S498-S516). The equation for calculating the speed of user  12  associated with METs expended during low intensity physical activity may be: 
       LowIntensitySpeed=(RawAEE_MET−1)/ G    
     For the LowIntensitySpeed calculation, the variable RawAEE_MET is the raw activity energy expenditure data calculated previously. The constant G is 0.49 h/km for low intensity physical activity, such as walking, that occurs while the velocity of user  12  is less than eight km/h. The constant  1  refers to one MET. 
     The equation for calculating the speed of user  12  associated with METs expended during high intensity physical activity may be: 
       HighIntensitySpeed=(CorAEE_MET−1)/ G    
     For the HighIntensitySpeed calculation, the variable CorAEE_MET is the corrected activity energy expenditure data calculated previously. The constant G is 0.95 h/km for high intensity physical activity, such as running, that occurs while the velocity of user  12  is greater than eight km/h. The constant  1  refers to one MET. 
     Computer device  16  may include appropriate input devices, output devices, mass storage media, processors, memory, or other components for receiving, processing, storing, and/or communicating information with other components of system  10 . As used in this document, the term “computer” is intended to encompass a docking station, personal computer, health station, workstation, network computer, wireless data port, wireless telephone, personal digital assistant (PDA), cellular telephone, game console, one or more processors within these or other devices, or any other suitable processing device. It will be understood that any number of computer devices  16  may be coupled to other computer devices  16  or communication network  18 . Computer devices  16  are generally operated by users  12  or coupled with activity monitors  14  to access web portal  40 . 
     In one embodiment, computer device  16  may comprise a browser application, such as an Internet web browser, for example. Browser application may allow user  12  of computer device  16  to navigate through, or “browse,” various Internet web sites or web pages. Computer device  16  may also comprise one or more graphics applications, such as a FLASH™ application for example, operable to display various types of data received via communication network  18 , such as graphics, video, and streaming data (such as video and/or audio), for example. 
     In one embodiment, activity monitor  14  may be coupled to computer device  16  such that user  12  can access web portal  40  without intervention from a third party (for example, a webmaster forwarding information). Activity monitor  14  may function as a digital key to web portal  40  so that users instantly access web portal  40  without having to launch an Internet web browser or type in a username or password. The user will be able to instantly interact with web portal  40 . 
     Server  32  is generally operable to provide an interface between users  12  and web portal  40 . One or more servers  32  may be web application servers or simple processors operable to allow users  12  to participate with web portal  40  via the communication network  18  using a standard user interface language such as, for example, the HyperText Markup Language (HTML). In some embodiments, one or more servers  32  may be physically distributed such that each server  32 , or multiple instances of each server  32 , may be located in a different physical location geographically remote from each other. In other embodiments, one or more servers  32  may be combined and/or integral to each other. One or more servers  32  may be implemented using a general-purpose personal computer (PC), a Macintosh, a workstation, a UNIX-based computer, a server computer, or any other suitable processing device. 
     In one embodiment, server  32  may be operable to configure and/or update all activity monitors  14  of a group of users  12 , such that all activity monitors  14  used by a particular business entity are configured and/or updated with the same functionality, such as using the same activity data metrics. For example, business entity may desire to have all activity data displayed with PAM points now instead of METs as was originally installed on activity monitor. This software update to utilize PAM points may include loading a new equation for calculating raw PAM points based on signals from accelerometer, and a new equation utilized by correction element for correcting the raw PAM points to a corrected PAM points value representing the actual energy expended by user. 
     In one embodiment, server  32  may be operable to provide security and/or authentication of users  12  or other persons or entities attempting to access web portal  40 . For example, servers  32  may essentially provide a firewall for entities attempting to access web portal  40 . In addition, servers  32  may be operable to translate one or more data protocols used by web portal  40  with one or more protocols used by applications hosted by one or more computer devices  16 . 
     In one embodiment, one or more servers  32  are web application servers operable to communicate dynamically updated information to particular computer devices  16  via communication network  18  including the identity of user  12 . For example, one or more servers  32  may communicate updated information on web portal  40  to particular computer devices  16  or activity monitors  14  via communication network  18 . 
     Server  32  may further comprise a memory that may be accessed or otherwise utilized by one or more components of interactive community. The memory may take the form of volatile or non-volatile memory including, without limitation, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), removable media, or any other suitable local or remote memory component. In general, the server memory may store various data including a user&#39;s account information, a user&#39;s goals, a user&#39;s activity data, and a population&#39;s activity data. 
     Databases  34  may be operable to store various data associated with web portal  40 , such as information regarding users  12 , computer devices  16 , and activity monitors  14 . Databases  34  may communicate with servers  32  such that servers  32  may store information, retrieve information, and share information with each other. Databases  34  may provide a backup in the case of outages or other failures of various components of web portal. Other architectures and components of servers  32  may be used without departing from the scope of this disclosure. 
     Web portal  40  may comprise one or more web sites. Web portal may also comprise hardware and software that provide users of the web with the ability to search for information on the web including information in the web portal  40 , documents, media, or other resources coupled to the web. The web sites on web portal  40  may include user&#39;s websites and informational websites. Web portal  40  provides a central location for users to get together with each other. 
     In one embodiment, web portal  40  may require user  12  to log in. User  12  may be required to enter a username and password to access personal page. In one embodiment, activity monitor  14  may be associated with a unique id number and web portal  40  may automatically log in user  12  to web portal when user  12  connects activity monitor  14  to computer device  16 . Activity monitor  14  may update information stored in database  34  of web portal  40 , such as updated activity energy expended data. Web portal  40  may comprise a personal coach page for user  12  comprising personal data of user  12 , such as the name, photo, address, city, country, weight, height, age, gender, and weight goal. Logic in web portal  40  may use personal data of user  12  to generate instructions or update goals. 
     The personal goals of user  12  in terms of a desired activity zone level and a desired weight may be calculated and displayed on a page in web portal  40 . Such calculations may be based on the personal data of user  12 , such as weight, height, age, and gender, as well as on other personal parameters that can be changed and/or updated on a preferences page and/or on the METs expended of the first week and/or a numerical parameter representing the motivation of user  12 . Upon approval of user, the calculated goals are set to be reached at the end of a specified time period, such as six months. During this period, the personal user page may provide information concerning the personal history of user  12  in terms of activity, body weight, and advice comprising suggestions for reaching the personal goals, such as walking a half an hour every day and running five km every day. 
     In one embodiment, web portal  40  comprises a resource page including links to interesting pages that may help user  12  reach the personal goals, such as a link to a page containing recipes which support a healthy lifestyle, a link to a service providing direct access to an instructor or dietician, and a link containing information on regional activities. If a goal is reached by user  12 , the personal page may display a message congratulating user  12  or send an actual congratulations post card to user&#39;s address. A special printer associated with web portal may do this automatically. 
       FIG. 2  is a simplified block diagram that illustrates an activity monitor apparatus used in the system in accordance with a particular embodiment of the present invention. Activity monitor  14  includes an accelerometer  50 , a processor  52 , a memory  54 , a correction element  55 , a speed element  56 , a port  57 , a display  58 , a mode button  60 , a special event button  62 , one or more input buttons  64 , a skin  70 , and a clip  80 . Display  58  is operable to display an activity meter  59  and several different modes including daily points  58 A, average daily points for a week  58 B, activity zone minutes  58 C, daily calories  58 D, total weekly calories  58 E, daily distance traveled  58 F, total weekly distance traveled  58 G, auxiliary mode  58 H, special event mode  581 , a clock  58 J, and speed  58 K. 
     Accelerometer  50  is a device that is used to convert an acceleration from gravity or from motion into an electrical signal. The input for accelerometer  50  is generally gravity or motion. Accelerometer  50  may measure acceleration in units of “g&#39;s.” One “g” is defined as the earth&#39;s gravitational pull on an object or a person. For example, 1 g represents the acceleration exerted by the Earth&#39;s gravity on an object or person (for example, a cell phone on a desk experiences 1 g of acceleration). The acceleration range experienced by a person when walking is between 0.1-2.0 g. In one embodiment, accelerometer  50  may be a uni-axial sensor that measures up and down movement of user along the vertical axis. Accelerometer  50  may determine the raw activity energy expended data by user  12 . Accelerometer  50  is explained in more detail below in  FIG. 3 . 
     Processor  52  controls the operation and administration of activity monitor  14  by processing information and signals. Processor  52  includes any suitable hardware, software, or both that operate to control and process signals. Processor  52  may be microprocessors, controllers, or any other suitable computing devices, resources, or combination of hardware, software and/or encoded logic. For example, processor  52  may be used to calculate the raw activity energy expended data by utilizing data from accelerometer  50 . Processor  52  may also be used by correction element  55  and speed element  56  to determine the corrected activity energy ended data and the speed of user  12 . 
     Memory  54  may be accessed or otherwise utilized by activity monitor  14 . Memory  54  may take the form of volatile or non-volatile memory including, without limitation, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), removable media, or any other suitable local or remote memory component. In general, memory  54  may store various data including data from accelerometer, data from processor, and data from web portal. Memory may also include equations and predetermined constants associated with correction element  55  and speed element  56 . 
     Port  56  may communicate information and signals to one or more computer devices  16  and receive information and signals from one or more computer devices  16 . Port  56  may also communicate information and signals to communication network  18  and receive information and signals from communication network  18 . Port  56  may represent any connection, real or virtual, including any suitable hardware and/or software that may allow activity monitor  14  to exchange information and signals with communication network  18 , one or more computer devices  14 , and/or other elements of system  10 . For example, port  56  enables activity monitor  14  to receive data from web portal  40 . Port  56  further enables activity monitor to transmit data to web portal  40  including all updated activity data. Port may be a serial communication port or a Universal Serial Bus (USB) port. 
     Display  58  is operable to display one or more images in one or more formats. Images viewed in display  58  may include daily points  58 A, average daily points for a week  58 B, activity zone minutes  58 C, daily calories  58 D, total weekly calories  58 E, daily distance traveled  58 F, total weekly distance traveled  58 G, auxiliary mode  58 H, special event mode  581 , a clock  58 J, speed  58 K, and an activity meter  59 . 
     Daily points  58 A may be viewed on display  58 . Daily points  58 A may represent any activity data metric associated with activity energy expended. For example, if activity monitor utilized the MET as the activity data metric, then METs expended for the day may be viewed by user  12 . The daily points  58 A provide user  12  with a simple and straightforward method to quantify and express the total amount of activity that user  12  achieves over a single day. The average daily points for a week  58 B allows user  12  to track how consistent user  12  has been active for the past seven days. Web portal  40  or other literature may indicate the amount of daily points  58 A users  12  should strive to accumulate to achieve a healthy lifestyle. By displaying a simple format, such as PAM points or METs, activity monitor  14  engages user  12  to stay active until user  12  has expended enough energy. Correction element  55  allows for activity monitor  14  to calculate and display the accurate amount of activity energy expended data, such as PAM points or METs, even when user  12  is engaged in high intensity physical activity. 
     Activity zone minutes  58 C may be viewed on display  58 . Activity zones may display life zone minutes, health zone minutes, and sport zone minutes. The activity zones may also be called light zone minutes, medium zone minutes, and heavy zone minutes as described in  FIG. 1  above. Life zone minutes may include very light activity, such as slow walking but not sitting down. Health zone minutes may include walking activity (faster than 4 km/h) or comparable activity consistent with recommendations from the medical community necessary for a beneficial health effect, i.e., such as walking thirty minutes a day most days of the week. Sport zone minutes may include running activity or activity with similar physical intensity. Web portal  40  or other literature may indicate the amount of time user  12  should strive to accumulate in the activity zones to achieve a healthy lifestyle. Displaying activity zone minutes  58 C engages user  12  to stay active until user  12  has accumulated enough activity zone minutes  58 C in each associated activity zone. 
     Daily calories expended  58 D may be viewed on display  58 . Correction element  55  allows for activity monitor  14  to calculate and display the accurate amount of calories expended even when user  12  is engaged in high intensity physical activity. The total weekly calories expended  58 E may also be viewed on display  58 . Web portal  40  or other literature may indicate the amount of calories user  12  should expend to achieve a healthy lifestyle. Displaying the amount of calories expended engages user to stay active until user  12  has expended enough calories. 
     Daily distance traveled  58 F may be viewed on display  58 . Activity monitor  14  may allow user  12  to set the measurement of distance including feet, miles or kilometers, etcetera. Total weekly distance  58 G traveled may also be viewed on display  58 . Web portal  40  or other literature may indicate the amount of distance users  12  should travel to achieve a healthy lifestyle. Displaying the amount of distance traveled engages user  12  to stay active until user  12  has traveled far enough. 
     Auxiliary mode  58 H may be viewed on display  58 . In auxiliary mode  58 H, user  12  may manually input numbers into activity monitor  14 . For example, a physician may give user  12  a regimen to take three pills a day or eat five vegetables a day. Physician or user  12  may input this information into web portal  40 . Web portal  40  may transmit this information to activity monitor  14  such that activity monitor  14  may display this information. Activity monitor  14  may be operable for user  12  to manually input each time user  12  takes a pill or eats a vegetable, such that the auxiliary mode displays the updated information. User  12  may press a button on activity monitor  14  for every pill or vegetable. User  12  may connect activity monitor  14  to web portal  40 , such that auxiliary mode  58 H information is automatically transmitted to web portal  40 . Physician may monitor web portal  40  to make sure user  12  is in compliance of a regimen (for example, user is taking the number of pills per day and eating the number of vegetables per day). Auxiliary mode  58 H may enable user  12  to properly track a diet regimen. Users  12  may not remember how many pills that they have taken throughout the day, and auxiliary mode  58 H enables users  12  to track their personal regimen. Physicians may also monitor their patients to make sure that patients are compliant with the regimen prescribed for them. 
     Special event mode  581  may be viewed on display  58 . Special event mode  581  enables user  12  to begin special event  581  and to end special event  581 . Additionally, special event mode  581  enables machines, like a treadmill, to begin a special event and to end a special event. For example, a treadmill may send a signal to activity monitor  14  to begin a special event when the treadmill is turned on and to end a special event when the treadmill is turned off. The activity monitor  14  may track the activity data during the special event  581  time period, such that user  12  can monitor activity of specific events. Alternatively, user  12  may manually press a button for special event  581  to begin at the start of a marathon and manually press a button for special event  581  to end when user  12  crosses the finish line. Special event mode  581  may enable users to monitor specific activity events, which engages users  12  to become more active. 
     Clock  58 J may be viewed on display  58 . Clock  58 J may be the time of day. Clock  58 J may also be a stopwatch to monitor the amount of time spent on an activity. Activity meter  59  may be viewed on display  58 . Activity meter  59  may comprise one or more bars such that no bars are displayed while user  12  is stationary, and the number of bars displayed will increase as user&#39;s current activity level increases. 
     Speed  58 K may be viewed on display  58 . Speed may be displayed in any suitable units, such as kilometers per hour, miles per hour, etc. By displaying speed  58 K, activity monitor  14  engages user  12  to stay active because user  12  has real-time knowledge of current speed. Speed element  56  allows for activity monitor  14  to calculate and display the accurate speed of user  12  even when user  12  is engaged in high intensity physical activity. 
     Mode button  60  on activity monitor  14  enables user  12  to toggle through one or more display modes for user  12  to view. For example, user  12  may press mode button to toggle display  58  from daily points to daily calories expended  58 D to special event mode  581 , etcetera. Special event button  62  on activity monitor  14  enables user  12  to begin and to end a special event. One or more input buttons  64  on activity monitor  14  enable user  12  to input information like incrementing the counter in auxiliary mode  58 H. 
     Skin  70  encases the outside of activity monitor  14 . Skin  70  may be removable and replaced with one or more skins  70 . Skin  70  may have different features including a different color, material, and texture. Clip  80  may attach to back of activity monitor  14 . Clip  80  enables user  12  to easily attach activity monitor  14  to an article of clothing. For example, clip  80  associated with activity monitor  14  comprising a single uni-axial accelerometer  50  allows accelerometer  50  to properly measure up and down movement of user  12  along the vertical axis. Clip  80  may be removable and replaced with one or more clips  80 . Clip  80  may also have different features including a different color, material, and texture. 
       FIG. 3  is a simplified block diagram that illustrates an activity monitor generating signals in response to a user&#39;s movement. For purposes of teaching and discussion, it is useful to provide some overview as to the way in which the following invention operates. The following foundational information may be viewed as a basis from which the present invention may be properly explained. 
     The circuitry of activity monitor  14  may comprise a single uni-axial accelerometer  50   a,  such as a uni-axial piezo-electric accelerometer  50   a,  which registers up and down body movement of user  12  along the vertical axis. Other types of accelerometer may be employed, such as piezo-resistive accelerometers, capacitive accelerometers, or other types of measuring methods to determine acceleration. The aforementioned clip in  FIG. 2  facilitates attachment of activity monitor to user  12 , such as attaching to the belt of user  12 , in such a way that ensures a substantially horizontal position when user  12  is standing upright. This allows the uni-axial accelerometer  50   a  to obtain accurate measurements occurring along the vertical axis. In other embodiments, it is possible to use multiple accelerometer sensors  50   b,    50   c  to measure different movements of user  12  along one or more axis. 
     Accelerometer  50   a  generates signals associated with movements of user  12 . Signals may be filtered using a band-pass filter to make sure that the signals occur in a frequency range typical for human motion, such as from 0.5 to 5 Hz with an amplitude of less than 5 G. Signal may be an analogous signal, such that a voltage fluctuates in a range from 0 mV to 10 mV. 
     This signal is subsequently amplified by means of amplification circuitry  72  and converted to a digital sequence of numbers by means of an A/D converter  78  with a sample frequency, such as 32 Hz. A dedicated processor calculates the average of the absolute value of the acceleration data over a specified time, such as the last second, last minute, last day or the last week. The average of the absolute value of the acceleration data over a specified time is used to obtain the raw activity energy expended data. 
     For example, as described above in  FIG. 1 , the formula for calculating the raw activity energy expended data in METs may be: 
       RawAEE_MET=( c*|a| )+1 
     To calculate the average value of the MET over a certain period of time, such as a day, the signal may be processed as follows. The signal, which fluctuates within the said range of 0 mV to 10 mV, is amplified by an amplification factor and sampled by the A/D converter  78 , which then generates a sample value, such as an integer in a range from 0 to 1024. Subsequently the absolute value is calculated so that the average of the values may represent the variable |a|. The constant c may be a predetermined number, such that the value of c may be determined by comparing the |a| value in METs with the expected value in METs obtained by measuring the actual energy expended by a plurality of subjects. 
     In one embodiment, activity monitor  14  may utilize a calibration factor to compensate for variations specific to the accelerometer type used. For example, piezo-electric sensor variations are plus or minus five percent. Therefore, a calibration factor for piezo-electric sensors may be in a range from 0.95 to 1.05. 
     Processor  58  may store the RawAEE_MET in memory. Activity monitor  14  may display RawAEE_MET or it may determine that correction element  55  and/or speed element  56  should process the RawAEE_MET. 
       FIG. 4A  is a graph illustrating an example equation for calculating the expected activity energy expended data in METs. In one embodiment, correction element  55  may utilize an equation to determine the corrected activity energy expenditure data (CorAEE). The equation utilized by correction element  55  may be based on the expected activity energy expenditure data (ExpAEE). The expected activity energy expenditure data for a particular activity data metric may be determined by a formula that expresses a relationship between the actual energy expended during low intensity physical activity, such as walking, and the actual energy expended during high intensity physical activity, such as running. 
     For example, the equation for calculating the expected activity energy expenditure data using the MET as the physical activity metric may be a function of low intensity physical activity, such as walking, and a function of high intensity physical activity, such as running, as published by the American College of Sports Medicine (Ainsworth et al., Compendium of physical activities: An update of activity codes and MET intensities, Med. Sci. Sports. Exerc. 2000, S498-S516). This equation for calculating the expected activity energy expenditure data in METs may be: 
       ExpAEE_MET=( G*v )+1 
     The variable v used to calculate ExpAEE_MET is the velocity of user  12  in terms of km/h. The constant G is 0.49 h/km for low intensity physical activity, such as walking, that occurs while the velocity of user  12  is less than eight km/h. The constant G is 0.95 h/km for high intensity physical activity, such as running, that occurs while the velocity of user  12  is greater than eight km/h. The constant G represents the gradient, such that activity energy expended increases at a gradient of 0.95 h/km during high intensity physical activity and a gradient of 0.49 h/km during low intensity physical activity. The constant  1  refers to one MET. This equation for the expected activity energy expenditure data is illustrated by the graph in  FIG. 4A .  FIG. 4B  is a graph illustrating step one of an example equation for calculating the corrected activity energy expended data in METs. The equation for determining the corrected activity energy expenditure data in METs may be determined by referencing the equation of the expected activity energy expenditure data in METs. This equation for calculating the corrected activity energy expenditure in METs may be: 
       CorAEE_MET=(RawAEE_MET− T )* B+F    
     The variable RawAEE_MET used in this equation is the value determined by activity monitor  14  in a previous calculation described above for calculating the raw METs expended by user  12 . The constants, T, B, and F, are all associated with determining the corrected activity energy expenditure in METs. The constants, T, B, and F, may be a predetermined value stored in activity monitor  14 . These predetermined values associated with the constants may be stored in activity monitor  14  during the manufacture process of activity monitor, by downloading new software for activity monitor, or any other suitable way. 
     The constant T may be a predetermined value representing a threshold value associated with high intensity physical activity, such that the threshold value is a value from the raw activity energy expended as calculated by activity monitor  14  based on signals from the single uni-axial accelerometer. All raw activity energy expended data above threshold value, T, may be associated with high intensity physical activity, such as running. For example, the threshold value associated with high intensity physical activity, such as running, may be all raw values greater than five METs. As will be explained later, this constant T may also be used to determine when correction element  55  should be utilized to correct raw activity energy expended data. 
     As illustrated in the graph of  FIG. 4B , the first step of calculating the corrected activity energy expenditure data in METs may involve subtracting the constant T from the variable RawAEE_MET. 
       FIG. 4C  is a graph illustrating step two of an example equation for calculating the corrected activity energy expended data in METs. The constant B may be a predetermined value representing the gradient of the corrected activity energy expenditure data in METs. For example, B may be the quotient of the gradient G of the expected raw activity energy expenditure data in METs divided by the gradient of the raw activity energy expenditure data in METs. As illustrated in the graph of  FIG. 4C , the second step of calculating the corrected activity energy expenditure data in METs may involve multiplying the factor B to the value obtained from subtracting the constant T from the variable RawAEE MET. 
       FIG. 4D  is a graph illustrating step three of an example equation for calculating the corrected activity energy expended data in METs. The constant F may be a predetermined value representing the offset value to apply to this equation, such that the offset value results in the corrected activity energy expenditure data in METs to essentially map the expected activity energy expenditure data in METs. As illustrated in the graph of  FIG. 4D , the third step of calculating the corrected activity energy expenditure data in METs may involve adding the offset, F, to the value obtained by multiplying the factor B to the value obtained from subtracting the constant T from the variable RawAEE MET. 
       FIG. 4E  is a graph illustrating an example equation for calculating the speed of user based on METs expended. For example, the equation for calculating the speed of user  12  utilizing the MET as the physical activity metric may be a function of low intensity physical activity, such as walking, and a function of high intensity physical activity, such as running, as published by the American College of Sports Medicine (Ainsworth et al., Compendium of physical activities: An update of activity codes and MET intensities, Med. Sci. Sports. Exerc. 2000, S498-S516). The equation for calculating the speed of user  12  associated with METS expended during low intensity physical activity may be: 
       LowIntensitySpeed=(RawAEE_MET−1) /G    
     For the LowIntensitySpeed calculation, the variable RawAEE_MET is the raw activity energy expenditure data calculated previously. The constant G is 0.49 h/km for low intensity physical activity, such as walking, that occurs while the velocity of user  12  is less than eight km/h. The constant  1  refers to one MET. 
     The equation for calculating the speed of user  12  associated with METS expended during high intensity physical activity may be: 
       HighIntensitySpeed=(CorAEE_MET−1) /G    
     For the HighIntensitySpeed calculation, the variable CorAEE_MET is the corrected activity energy expenditure data calculated previously. The constant G is 0.95 h/km for high intensity physical activity, such as running, that occurs while the velocity of user  12  is greater than eight km/h. The constant  1  refers to one MET. 
       FIG. 5  is a flowchart that illustrates an example method of correction element  55  and speed element  56  in accordance with an embodiment of the present invention. 
     The flowchart begins at step  502 , when user wears activity monitor. Activity monitor may comprise a single uni-axial accelerometer. Activity monitor may be preprogrammed with equations and the associated predetermined constants of the equations for calculating the raw activity energy expenditure data in METs, the corrected activity energy expenditure data in METs, and the speed of user based on METs expended by user. As a result, user may wear a new activity monitor and view the actual energy expended by user and the speed of user, such that user never has to input any personal information for these calculations. 
     At step  504 , activity monitor determines if user is engaged in low or high intensity physical activity. The raw activity energy expenditure data in METs can be compared to the predetermined threshold constant, T. The predetermined threshold constant, T, may represent the value where raw activity energy expenditure data deviates from the expected activity energy expenditure data as a result of high intensity physical activity. If the raw activity energy expenditure data in METs is equal to or greater than the predetermined threshold constant, T, then user is engaged in high intensity physical activity and activity monitor moves to step  512  to utilize correction element. Otherwise, if the raw activity energy expenditure data in METs is less than the predetermined threshold constant, T, then user is engaged in low intensity physical activity and activity monitor moves to step  506 . 
     At step  506 , activity monitor has determined user is engaged in low intensity physical activity. When engaged in low intensity physical activity, the single uni-axial accelerometer generates accurate values for raw activity energy expenditure data. Therefore, activity monitor displays the raw activity energy expenditure data in METs to user. 
     At step  508 , speed element determines speed of user based on the raw activity energy expended. At step  510 , activity monitor displays speed to user. 
     At step  512 , activity monitor has determined user is engaged in high intensity physical activity. When engaged in high intensity physical activity, the single uni-axial accelerometer generates inaccurate values for raw activity energy expenditure data. Therefore, activity monitor communicated the raw activity energy expenditure data in METs to correction element. Correction element utilizes a predetermined equation associated with METs to calculate a corrected activity energy expenditure data in METs, which represents the actual METs expended by user. At step  514 , activity monitor displays the corrected activity energy expenditure data in METs to user. 
     At step  516 , speed element determines speed of user based on the corrected activity energy expended. At step  518 , activity monitor displays speed to user. 
     It is important to note that the stages and steps described above illustrate only some of the possible scenarios that may be executed by, or within, the present system. Some of these stages and/or steps may be deleted or removed where appropriate, or these stages and/or steps may be modified, enhanced, or changed considerably without departing from the scope of the present invention. In addition, a number of these operations have been described as being executed concurrently with, or in parallel to, one or more additional operations. However, the timing of these operations may be altered. The preceding example flows have been offered for purposes of teaching and discussion. Substantial flexibility is provided by the tendered architecture in that any suitable arrangements, chronologies, configurations, and timing mechanisms may be provided without departing from the broad scope of the present invention. Accordingly, communications capabilities, data processing features and elements, suitable infrastructure, and any other appropriate software; hardware, or data storage objects may be included within system  10  to effectuate the tasks and operations of the elements and activities associated with executing compatibility functions. 
     Although the present invention has been described in detail with reference to particular embodiments, it should be understood that various other changes, substitutions, and alterations may be made hereto without departing from the spirit and scope of the present invention. The illustrated network architecture of  FIG. 1  has only been offered for purposes of example and teaching. Suitable alternatives and substitutions are envisioned and contemplated by the present invention: such alternatives and substitutions being clearly within the broad scope of system  10 . For example, the use of the LAN could easily be replaced by a virtual private network (VPN), a metropolitan area network (MAN), a wide area network (WAN), a wireless LAN (WLAN), or any other element that facilitates data propagation. Using analogous reasoning, the computer device illustrated by  FIG. 1  may be supplanted by docking stations, health stations, gaming consoles, or any other suitable devices that are conducive to network communications. Furthermore, the activity monitor is not confined to displaying only the modes shown in  FIG. 2 . 
     Although the present invention has been described with several embodiments, a myriad of changes, variations, alterations, transformations, and modifications may be suggested to one skilled in the art, and it is intended that the present invention encompass such changes, variations, alterations, transformations, and modifications as falling within the scope of the appended claims.