European Journal of Applied Physiology

, Volume 112, Issue 6, pp 2289–2301

Muscle power failure in mobility-limited older adults: preserved single fiber function despite lower whole muscle size, quality and rate of neuromuscular activation

  • Kieran F. Reid
  • Gheorghe Doros
  • David J. Clark
  • Carolynn Patten
  • Robert J. Carabello
  • Gregory J. Cloutier
  • Edward M. Phillips
  • Lisa S. Krivickas
  • Walter R. Frontera
  • Roger A. Fielding
Original Article

DOI: 10.1007/s00421-011-2200-0

Cite this article as:
Reid, K.F., Doros, G., Clark, D.J. et al. Eur J Appl Physiol (2012) 112: 2289. doi:10.1007/s00421-011-2200-0

Abstract

This study investigated the physiological and gender determinants of the age-related loss of muscle power in 31 healthy middle-aged adults (aged 40–55 years), 28 healthy older adults (70–85 years) and 34 mobility-limited older adults (70–85 years). We hypothesized that leg extensor muscle power would be significantly lower in mobility-limited elders relative to both healthy groups and sought to characterize the physiological mechanisms associated with the reduction of muscle power with aging. Computed tomography was utilized to assess mid-thigh body composition and calculate specific muscle power and strength. Surface electromyography was used to assess rate of neuromuscular activation and muscle biopsies were taken to evaluate single muscle fiber contractile properties. Peak muscle power, strength, muscle cross-sectional area, specific muscle power and rate of neuromuscular activation were significantly lower among mobility-limited elders compared to both healthy groups (P ≤ 0.05). Mobility-limited older participants had greater deposits of intermuscular adipose tissue (P < 0.001). Single fiber contractile properties of type I and type IIA muscle fibers were preserved in mobility-limited elders relative to both healthy groups. Male gender was associated with greater decrements in peak and specific muscle power among mobility-limited participants. Impairments in the rate of neuromuscular activation and concomitant reductions in muscle quality are important physiological mechanisms contributing to muscle power deficits and mobility limitations. The dissociation between age-related changes at the whole muscle and single fiber level suggest that, even among older adults with overt mobility problems, contractile properties of surviving muscle fibers are preserved in an attempt to maintain overall muscle function.

Keywords

AgingMobilityMuscle powerSingle muscle fiber properties

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Kieran F. Reid
    • 1
  • Gheorghe Doros
    • 2
  • David J. Clark
    • 3
    • 4
  • Carolynn Patten
    • 3
    • 5
  • Robert J. Carabello
    • 1
  • Gregory J. Cloutier
    • 1
  • Edward M. Phillips
    • 1
    • 6
  • Lisa S. Krivickas
    • 6
  • Walter R. Frontera
    • 6
    • 7
    • 8
  • Roger A. Fielding
    • 1
  1. 1.Nutrition, Exercise Physiology and Sarcopenia LaboratoryJean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging at Tufts UniversityBostonUSA
  2. 2.Department of BiostatisticsBoston University School of Public HealthBostonUSA
  3. 3.Brain Rehabilitation Research CenterMalcom Randall VA Medical CenterGainesvilleUSA
  4. 4.Department of Aging and Geriatric ResearchUniversity of FloridaGainesvilleUSA
  5. 5.Department of Physical TherapyUniversity of FloridaGainesvilleUSA
  6. 6.Department of Physical Medicine and RehabilitationHarvard Medical School and Spaulding Rehabilitation HospitalBostonUSA
  7. 7.Department of Physical Medicine and RehabilitationUniversity of Puerto Rico School of MedicineSan JuanUSA
  8. 8.Department of PhysiologyUniversity of Puerto Rico School of MedicineSan JuanUSA