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Age-dependent muscle adaptation after chronic stretch-shortening contractions in rats

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  • Personal Author:
  • Description:
    Age-related differences in contraction-induced adaptation have been well characterized especially for young and old rodent models but much less so at intermediate ages. Therefore, additional research is warranted to determine to what extent alterations in adaptation are due to maturation versus aging per se. The purpose of our study was to evaluate muscles of Fisher 344XBrown Norway rats of various ages following one month of exposure to stretch-shortening contractions (SSCs). With exposure, muscles mass increased by approximately 10% for 27 and 30 month old rats vs. approximately 20% for 3 and 6 month old rats (P < 0.05). For 3 month old rats, maximum isometric force and dynamic peak force increased by 22 +/- 8% and 27 +/- 10%, respectively (P < 0.05). For 6 month old rats, these forces were unaltered by exposure and positive work capacity diminished by 27 +/- 2% (P = 0.006). By 30 months of age, age-related deficits in maximum isometric force, peak force, negative work, and positive work were apparent and SSC exposure was ineffective at counteracting such deficits. Recovery from fatigue was also tested and exposure-induced improvements in fatigue recovery were indicated for 6 month old rats and to a lesser extent for 3 month old rats whereas no such effect was observed for older rats. Alterations in fatigue recovery were accompanied by evidence of substantial type IIb to IIx fiber type shifting. These results highlight the exceptional adaptive capacity for strength at a young age, the inclination for adaptation in fatigue recovery at early adulthood, and diminished adaptation for muscle performance in general beginning at late adulthood. Such findings motivate careful investigation to determine appropriate SSC exposures at all stages of life. [Description provided by NIOSH]
  • Subjects:
  • Keywords:
  • ISSN:
    2152-5250
  • Document Type:
    Text
  • Genre:
    Journal Article
  • Place as Subject:
  • CIO:
    National Institute for Occupational Safety and Health (NIOSH)
  • Division:
    HELD - Health Effects Laboratory Division
  • Topic:
    Workplace Safety & Health
  • Location:
    North America
  • Pages in Document:
    1-13
  • Volume:
    7
  • Issue:
    1
  • NIOSHTIC Number:
    nn:20047241
  • Citation:
    Aging Dis 2016 Feb; 7(1):1-13
  • Contact Point Address:
    Erik P. Rader, PhD, MS L3014, 1095 Willowdale Rd., Morgantown, WV, 26505
  • Email:
    WLZ4@cdc.gov
  • Federal Fiscal Year:
    2016
  • Peer Reviewed:
    True
  • Source Full Name:
    Aging and Disease
  • Collection(s):
  • Main Document Checksum:
    urn:sha-512:0aea0741c5e62b911f7d4d068a6746c565de0ab9d352dad75a778800a86a9d7d69c24d77b30adf368d3e8971f71e482a1b9842db0ff16f285371aa3b10c9328f
  • Download URL:
  • File Type:
    Filetype[PDF - 1.33 MB ]
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