title: Fatigue of elbow flexor muscles in younger and older adults.
abstract: The aim of this study was to assess differences in the behavior of fatigue-related measures of neuromuscular function between younger (n = 10; 20-35 years) and older (n = 11; >65 years) healthy adults. Measures reflecting changes in voluntary activation, neuromuscular propagation, metabolite build-up, and excitation-contraction coupling processes were taken before, during, and after a sustained maximum elbow-flexion fatigue task. We found a greater role for a failure in voluntary activation (central fatigue) in about half of the older subjects compared with none of the younger subjects to explain the decrease in force-generating capacity with sustained activity. In contrast, similar behaviors in measures reflecting changes in peripheral mechanisms were noted for the two age groups. These results point to a potential shift in fatigue mechanisms with age, with a greater contribution of central fatigue in some older adults.
authors.affiliation: Physical Therapy Graduate Program, University of Iowa, 2600 Steindler Building, Iowa City, Iowa 52242, USA. martin-bilodeau@uiowa.edu
authors.forename: M
authors.initials: M
authors.lastname: Bilodeau
authors.forename: M D
authors.initials: MD
authors.lastname: Erb
authors.forename: J M
authors.initials: JM
authors.lastname: Nichols
authors.forename: K L
authors.initials: KL
authors.lastname: Joiner
authors.forename: J B
authors.initials: JB
authors.lastname: Weeks
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D004551:Elbow Joint / Q000502:physiology*; D004558:Electric Stimulation; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology; D012737:Sex Factors; D019415:Torque