Lower Body and Extremity Flexibility and Strength do Not Correlate With Standing, Stooping and Crouching Performances
Condition: Flexibility; Strength
Study type: Observational

Summary: 
      Standing, stooping and crouching are considered important physical demands of the work, which
      are among the 20 physical work demands defined in the Dictionary of Occupational Titles(1,
      2). Agricultural workers, underground miners, aircraft baggage handlers, plumbers, mechanics
      and many other workers adopt these postures(3-7). These postures are also used in daily
      activities such as gardening, shopping andcleaning(8).Standing describes an upright position
      without moving(2). Maintaining this position requires sustained musclea ctivity in various
      muscles of the body known as the antigravity muscles(9). Stooping consists of bending the
      torso forward and down with the legs in a relatively straight position. Crouching is an
      activity performed with the flexion of the hip, knee and ankle while the trunk is in a
      vertical position. During stooping, the lower back and posterior leg muscles are stretched.
      Crouching involves similar length changes, particularly in the quadriceps and ankle plantar
      flexor muscles, as a result of significant flexion in the knee and ankle joints.Unlike
      standing, as the hip and knee joints are fully flexed during crouching, activation of the
      quadriceps and calf muscles is potentially required to support lower extremities and weight
      transfer between limbs(10).

      Consideration of the flexibility defined as the maximum range of motion, and the muscular
      strength associated with the amount of external force a muscle can exert(11, 12), may provide
      a different perspective to the health care professionals during the interpretation of the
      work or daily activities. Knowing the relationship between standing, stooping and crouching
      performances with the direct measurement methods such as flexibility and strength may help to
      make a more accurate decision during the health care assessments and guiding individuals who
      have difficulties in these activities to the appropriate rehabilitation program. Starting
      from this point of view, in this study, we aimed to evaluate the relationship between
      flexibility and muscular strength tests with standing, stooping and crouching performances.
    

Detailed description: 
      Participants Over the age of 18, 97 sedentary young adults studying at university were
      included in this cross-sectional study by convenience sampling. Announcement about the study
      was made via e-mail and social media.Individuals who volunteered to participate in the study
      and met the inclusion criteria were enrolled.Inclusion criteria were the absence of any
      orthopaedic, neurological, rheumatologic or metabolic diseases that cause musculoskeletal
      involvement, and the absence of a history of surgery on the related extremities. Individuals
      who had acquired the skills to practice these tests before the study and who had regular
      physical activity or sports participation (exercising at least 150 minutes per week) were
      excluded from the study (13). The research protocol was approved by the Institutional Review
      Board. Written informed consent was obtained from all participants before the study.

      Assessments After questioning the demographic characteristics of the volunteers, modified
      sit-and-reach (MSR), isometric back-leg strength (IBLS) and Valpar 9 Whole Body Range of
      Motion (WBROM)tests were completed with the participants who met the eligibility criteria.
      After detailed explanation, the tests were applied to the participants under the supervision
      of the same physiotherapistin the school of physiotherapy. Firstly WBROM, then IBLS and MSR
      tests were performed. After each test, participants were given a rest period of 10 minutes in
      a sitting position.

      To evaluate standing, stooping and crouching performances, WBROM test was used.This
      testprovides information on range of motion, agility and endurance.In this test, which took
      approximately 30 minutes, the participant was positioned in front of the test panel with the
      upper frame 6 inches above the head. The participant unscrewed the 22 nuts to release and
      transfer three different shapes in the standing position in the first transfer, in the
      standing and stooping positions in the second, in the stooping and crouching positions in the
      third and in the crouching and standing positions in the last transfer, and retightened the
      nuts to fix the shapes. This test assesses participants' ability to stand, stoop and
      crouchwhile performing a manual task. The completion time of each transfer and total time
      were recorded as seconds(Christopherson & Hayes, 2006; Dailey, Keffala, & Sluka, 2015;
      Schult, Söderback, & Jacobs, 1995).

      MSR test was performed using Baseline™ modified sit and reach box with adjustable measuring
      bar. It has been reported in the literature that the standard SR test does not take into
      account differences in limb lengths or proportional differences between legs and arms, which
      is an important limitation of the test. MSR test that eliminates the possibility of error by
      creating a relative zero point for each case has been developed due to potential errors that
      may arise from differences in limb-length ratio between individuals (Hoeger, Hopkins, Button,
      & Palmer, 1990). At the beginning of this test, while the head, back and hips were against
      the wall and the soles of the feet were against the block, hands were placed on top of each
      other and the arms were extended to the front. In this position, only scapular abduction was
      performed while the head and back were in contact with the wall. The point where the
      fingertip touches the sliding measuring apparatus was determined as the individual relative
      zero point. After the determination of the initial position, the SR test was performed as
      standard. The participant was asked to reach out slowly with hands on top of each other and
      to advance the movable part of the test device with fingertips. The mean value of three
      trials was recorded in centimeters (cm).

      Isometric back and leg muscle strengths were assessed using a Baseline dynamometer. The
      dynamometer was connected via a hook to a platform with an adjustable chain. For isometric
      leg muscle strength assessment, participants were asked to spread their feet at shoulder
      width on the dynamometer platform and hold the dynamometer bars in forearm pronation position
      with both hands. After the participant was positioned with the knees slightly flexed, the
      head and back straight and the projection of the hip joint passing through the ankle,
      isometric leg strength was evaluated by asking the participant to extend the knees with
      maximum force vertically. A similar procedure was used for back muscle strength assessment.
      For this test, the participants were positioned with knees extended, trunk slightly flexed,
      arms straight and palms facing themselves. In this position, isometric back strength was
      evaluated by asking the participant to do back extension with maximum force. Leg and back
      muscle strength measurements were performed three times with one minute pause after each
      measurement and the mean value in kilograms (kg) was recorded (Hu et al., 2007).

      Statistical analysis The data obtained from the participants were recorded in SPSS 18.0
      statistical analysis program. Mean and standard deviation were calculated for descriptive
      data determined by measurement, and number and percentage (%) values were presented for
      descriptive data determined by counting. Since parametric conditions were met, Pearson
      Correlation Analysis was used to analyze the relationship between flexibility and muscular
      strength with standing, stooping and crouching performances. Significance level was accepted
      as p <0.05.
    

Observational model: Other
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Over the age of 18, 97 sedentary young adults studying at university
      
Keywords: flexibility, musclestrength, standing, stooping, crouching