# Use of Wearable Sensor Technology in Gait, Balance, and Range of Motion Analysis
## 5 A Taxonomy for Gait, Balance, RoM Analysis
### Gait Analysis
#### 5.1.1 Gait Analysis: Rhythm and Phases  
The most common gait parameters associated with rhythm and phases of gait are _gait cycles phases_, _stance time_, _swing time_, _step time_, _stride time_, _cadence_, and _walking ratio_[80; 104].  
In the gait cycle, there are two main phases called stance phase and swing phase. In the stance phase, the foot is in contact with the floor, while in the swing phase, the foot is moving through the air without making contact with the floor. However, researchers continue to expand the gait phases involved in a gait cycle to have a deeper and more detailed understanding of the gait cycle. [PERSON] et al. standardized the name of the different gait phases, going from the two main phases, stance phase and swing phase, to a granularity of phases in which the one that has the most phases contains eight phases: initial contact, loading response, mid stance, terminal stance, pre swing, initial swing, mid swing, and terminal swing [107].  
Researchers measure the time it takes subjects to complete each phase of gait. Swing time is the time that passes during swing phase, starting as soon as the foot gets off the floor until it makes contact with the floor again. Stance time is the time that passes during the stance phase, starting once the foot makes contact with the floor until it moves off the floor again. Researchers have found that stance phase is longer when the subject has a balance problem [104]. Stride time is the duration of a stride and the same procedure used to measure swing time and stance time can be used to calculate stride time. It can also be measured by adding up the swing time plus the stance time. Step time is the duration of a step. When data is recorded from wearable sensors, the data includes a timestamp. A timestamp is the time registered to a file or log that records when an event or data is added, removed, or modified. It is possible to calculate time based parameters by subtracting the timestamp of when the previous event occurred minus the timestamp of when the current event occurred [26; 28; 35; 36; 48; 51; 53; 61; 70].  
Cadence is the rate at which a subject walks, expressed in steps per minute. Researchers have found that cadence is usually between 98-138 steps per minute for healthy women and 91-135 steps per minute for healthy men, between the ages of 18-49 [108]. Researchers often approximate cadence by using a mean step time. As an example, if a subject's mean step time is around 0.5 s, the subject will execute approximately 120 steps in a minute. Using mean step time may not be ideal when the subject's walking pattern is asymmetrical. Cadence has been used to give quantitative data that serve as early indicators of neurological disorders, assess the daily living walking activities, and provide immediate bio-feedbacks [25; 26; 28; 43; 56; 65].  
Walking ratio represents the relationship between frequency and amplitude of movements of the legs. It can be calculated by dividing the mean step length by the cadence. Researchers have found that the mean walking ratio is 0.58 and it decreases when the person walks with fast, shorter steps such as in person with Parkinson's disease or Alzheimer's Disease [104].