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Slow rate of neuromuscular activation contributes to impaired movement acceleration and peak power in mobility‐limited older adults
Author(s) -
Clark David J,
Patten Carolynn,
Reid Kieran F,
Carabello Robert,
Phillips Edward M,
Fielding Roger A
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1163.9
Subject(s) - muscle power , sarcopenia , medicine , cardiology , physical medicine and rehabilitation , chemistry
Peak muscle power is a robust predictor of functional motor performance in older adults. A critical constituent of peak power is effective neuromuscular activation. This study investigated the relationship between pre‐movement activation rate, acceleration (Acc), and peak power (P peak ) for a leg press task in healthy and mobility‐limited older adults. METHODS 19 middle aged healthy (M H , 40–55y, 9 male), 19 older healthy (O H , 70–85y, 14 male), and 14 older mobility‐limited (O ML , 70–85y, 7 male, SPPB ≤ 9) adults participated. EMG was acquired from the quadriceps during 5 max effort leg press trials at 40% of 1‐rep max. EMG was rectified, smoothed, and normalized to peak from a maximal voluntary contraction (MVC). EMG from each trial was aligned to movement onset, then averaged and fit using linear regression to yield activation rate (slope). RESULTS O ML demonstrated markedly lower activation rate (.13 %MVC/ms, p<.02) than M H (.24) and O H (.26). Similarly, Acc (4.4 m/s 2 , p<.01) and P peak (536W, p<.01) were impaired in O ML relative to M H (6.5, 1057) and O H (5.8, 980). Across groups, activation rate was strongly related to Acc (R 2 =.66, p<.0001) and P peak (R 2 =.55, p<.001). CONCLUSION Attenuated rate of neuromuscular activation is associated with reduced movement acceleration and power production in mobility‐limited older adults. Supported by USDA 58‐1950‐7‐707and NIA RO1‐AG‐18844