title: Explosive force and fractionated reaction time in elderly low- and high-active women.
abstract: OBJECTIVE
  The purpose of this study was to determine whether muscle power, activation time, and neuromuscular stimulation are related to physical activity patterns in older women.
  
  
  METHODS
  Forty women (65-84 yr) were assigned to high-active (HA) and low-active (LA) groups on the basis of a historical activity questionnaire, and then they performed a series of maximal, voluntary, isometric knee extensions in a visually cued RT task. Fractionated RT measures were taken using three landmarks in the data: the presentation of the visual stimulus, the beginning of the EMG burst, and the initiation of force development. The rate and magnitude of neural stimulation were taken from surface EMG.
  
  
  RESULTS
  Peak torque was 15% greater, rate of torque development was 26% greater, motor time was 17% shorter, rate of EMG rise was 25% faster, and onset EMG magnitude was 15% greater in HA than in LA subjects (P<0.05).
  
  
  CONCLUSIONS
  These results indicate that older women with a history of vigorous activity can generate greater force, power, and motor output in comparison with their less active peers. The lower-body mass index of the HA subjects and 310% greater volume of physical activity are likely to account for the enhanced neuromuscular function seen. It is plausible that in addition to aging, physical inactivity is responsible for a large portion of the loss of neuromuscular function seen in older adults.
authors.affiliation: Department of Environmental and Health Sciences, Johnson State College, Johnson, VT, USA. Dain.LaRoche@unh.edu
authors.forename: Dain P
authors.initials: DP
authors.lastname: Laroche
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Knight
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Dickie
authors.forename: Mélanie
authors.initials: M
authors.lastname: Lussier
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Roy
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006801:Humans; D007866:Leg / Q000294:innervation / Q000502:physiology*; D008019:Life Style; D009043:Motor Activity / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology; D010809:Physical Fitness; D011930:Reaction Time / Q000502:physiology*; D019415:Torque