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Sarcolemmal excitability changes in normal human aging
Author(s) -
Lee James H.F.,
BolandFreitas Robert,
Ng Karl
Publication year - 2018
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.26058
Subject(s) - interquartile range , medicine , refractory period , tibialis anterior muscle , rectus femoris muscle , depolarization , skeletal muscle , cardiology , anatomy , electromyography , physical medicine and rehabilitation
ABSTRACT Introduction : The exact mechanisms underlying the loss of skeletal muscle bulk and power with normal human aging are not well established. Recording of muscle velocity recovery cycles (MVRCs) is an in‐vivo neurophysiologic technique we employed to assess the impact of age on sarcolemmal excitability. Methods : MVRC recordings were obtained from tibialis anterior ( n = 74) and rectus femoris ( n = 32) muscles in 74 healthy subjects (18–84 years, median age 35 years, interquartile range 29–55 years). Results : Increasing age was linearly associated with longer muscle relative refractory period (MRRP) and reduced early supernormality (ESN) in both tibialis anterior (MRRP: r 2 = 0.38, P < 0.001; ESN: r 2 = 0.33, P < 0.001) and rectus femoris (MRRP: r 2 = 0.30, P = 0.002; ESN: r 2 = 0.19, P = 0.01) muscles. Discussion : The results are consistent with progressive depolarization of the resting sarcolemmal potential with normal aging. This may be an important mechanism in explaining age‐related muscle decline. Muscle Nerve 57 : 981–988, 2018