title: Age-related effects on maximal and rapid hamstrings/quadriceps strength capacities and vertical jump power in young and older females.
abstract: OBJECTIVE
  Declines in hamstrings and quadriceps maximal and rapid strength are commonly reported as a consequence of aging; however, few studies have investigated the influence of age on maximal and rapid hamstrings to quadriceps (H/Q) strength ratios. This study aimed to examine the effects of age on leg extension and flexion maximal and rapid torque production, H/Q strength ratios, and muscle power in healthy, young and old females.
  
  
  METHODS
  Fifteen young (21 ± 2 years) and 15 old (69 ± 7 years) females performed 3 isometric leg extension and flexion maximal voluntary contractions (MVCs), from which peak torque (PT), early (0-30 ms) and late (0-200 ms) phase rate of torque development (RTD), and PT and RTD H/Q strength ratios were extracted. Lower-body peak power output (Pmax) was assessed through a vertical jump test.
  
  
  RESULTS
  Pmax, PT, and early (RTD30) and late (RTD200) RTD variables of the leg extensors and flexors were lower (P ≤ 0.048) and PT and RTD200 H/Q strength ratios were higher (P ≤ 0.030) in the old compared to the younger females; however, no difference was observed for RTD30 H/Q (P = 0.300). There were also significant negative relationships in the older (r = -0.616 and -0.522; P = 0.014 and 0.046) but not the younger (r = 0.295 and -0.109; P = 0.286 and 0.698) females between Pmaxand RTD30 and RTD200 H/Q strength ratios.
  
  
  CONCLUSIONS
  The higher RTD200 H/Q ratio for the older females may contribute to the muscle power deficits often observed in elderly populations. Practitioners may use these findings to help identify older adults with low muscle power capacities and possibly overall functional decline.
authors.affiliation: Department of Kinesiology and Sport Management, Texas Tech University, Lubbock, TX, USA. ty.palmer@ttu.edu.
authors.forename: Ty B
authors.initials: TB
authors.lastname: Palmer
authors.affiliation: School of Health Sciences, Kent State University, Kent, OH, USA.
authors.forename: Brittany N
authors.initials: BN
authors.lastname: Followay
authors.affiliation: Department of Kinesiology and Health Science, Utah State University, Logan, UT, USA.
authors.forename: Brennan J
authors.initials: BJ
authors.lastname: Thompson
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology*; D019415:Torque; D055815:Young Adult
keywords: Countermovement; H/Q ratio; Isometric; Peak torque; Rate of torque development