title: Squatting exercises in older adults: kinematic and kinetic comparisons.
abstract: OBJECTIVE
  Squatting activities may be used, within exercise programs, to preserve physical function in older adults. This study characterized the lower-extremity peak joint angles, peak moments, powers, work, impulse, and muscle recruitment patterns (electromyographic; EMG) associated with two types of squatting activities in elders.
  
  
  METHODS
  Twenty-two healthy, older adults (ages 70-85) performed three trials each of: 1) a squat to a self-selected depth (normal squat; SQ) and 2) a squat onto a chair with a standardized height of 43.8 cm (chair squat; CSQ). Descending and ascending phase joint kinematics and kinetics were obtained using a motion analysis system and inverse dynamics techniques. Results were averaged across the three trials. A 2 x 2 (activity x phase) ANOVA with repeated measures was used to examine the biomechanical differences among the two activities and phases. EMG temporal characteristics were qualitatively examined.
  
  
  RESULTS
  CSQ generated greater hip flexion angles, peak moments, power, and work, whereas SQ generated greater knee and ankle flexion angles, peak moments, power, and work. SQ generated a greater knee extensor impulse, a greater plantar flexor impulse and a greater total support impulse. The EMG temporal patterns were consistent with the kinetic data.
  
  
  CONCLUSIONS
  The results suggest that, with older adults, CSQ places greater demand on the hip extensors, whereas SQ places greater demand on the knee extensors and ankle plantar flexors. Clinicians may use these discriminate findings to more effectively target specific lower-extremity muscle groups when prescribing exercise for older adults.
authors.affiliation: Musculoskeletal Biomechanics Research Laboratory, Department of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA 90089, USA.
authors.forename: Sean
authors.initials: S
authors.lastname: Flanagan
authors.forename: George J
authors.initials: GJ
authors.lastname: Salem
authors.forename: Man-Ying
authors.initials: MY
authors.lastname: Wang
authors.forename: Serena E
authors.initials: SE
authors.lastname: Sanker
authors.forename: Gail A
authors.initials: GA
authors.lastname: Greendale
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001696:Biomechanical Phenomena; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D005081:Exercise Therapy; D005260:Female; D006615:Hip / Q000502:physiology; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D011187:Posture; D016059:Range of Motion, Articular