TY - JOUR
T1 - Aging impairs the recovery in mechanical muscle function following 4 days of disuse
AU - Hvid, Lars Grøndahl
AU - Suetta, C
AU - Nielsen, Jacob
AU - Jensen, Majbrit M
AU - Frandsen, U
AU - Ørtenblad, N
AU - Kjær, Michael
AU - Aagaard, P
N1 - Copyright © 2014 Elsevier Inc. All rights reserved.
PY - 2014/4
Y1 - 2014/4
N2 - As aged individuals are frequently exposed to short-term disuse caused by disease or musculoskeletal injury, it is important to understand how short-term disuse and subsequent retraining affect lower limb mechanical muscle function. The purpose of the present study was, therefore, to investigate the effect of 4days of lower limb disuse followed by 7days of active recovery on mechanical muscle function of the knee extensors in young (24.3±0.9years, n=11) and old (67.2±1.0years, n=11) recreationally active healthy males. Slow and moderate dynamic muscle strength were assessed using isokinetic dynamometry (60 and 180°s-1, respectively) along with isometric muscle strength and rapid muscle force capacity examined as contractile rate of force development (RFD), Impulse, and relative RFD (rRFD) during the initial phase of contraction (100ms time interval relative to onset of contraction). Prior to disuse, marked age-related differences (p<0.05) were observed in isometric and dynamic muscle strength (~35%) as well as in RFD and Impulse (~39%). Following disuse, young and old individuals experienced comparable decrements (p<0.05) in isometric strength (~9%), slow dynamic strength (~13%), and RFD and Impulse (~19%), whereas old individuals only experienced decrements (p<0.05) in moderate dynamic strength (12%) and rRFD (~17%). Following recovery, all measures of mechanical muscle function were restored in young individuals compared to pre-disuse values, while isometric, slow and moderate dynamic muscle strength remained suppressed (p<0.05) in old individuals (~8%) along with a tendency to suppressed RFD100 (p=0.068). In conclusion, 4days of lower limb disuse led to marked decrements in knee extensor mechanical muscle function in both young and old individuals, yet with greater decrements observed in moderate dynamic strength and rapid muscle force capacity in old individuals. While 7days of recovery - including free ambulation, one test session and a single session of strength training - was sufficient to restore mechanical muscle function in young individuals, old individuals appeared to have an impaired ability to fully recover as evidenced by suppressed values of isometric and dynamic muscle strength and rapid muscle force capacity. copy; 2014 Elsevier Inc.
AB - As aged individuals are frequently exposed to short-term disuse caused by disease or musculoskeletal injury, it is important to understand how short-term disuse and subsequent retraining affect lower limb mechanical muscle function. The purpose of the present study was, therefore, to investigate the effect of 4days of lower limb disuse followed by 7days of active recovery on mechanical muscle function of the knee extensors in young (24.3±0.9years, n=11) and old (67.2±1.0years, n=11) recreationally active healthy males. Slow and moderate dynamic muscle strength were assessed using isokinetic dynamometry (60 and 180°s-1, respectively) along with isometric muscle strength and rapid muscle force capacity examined as contractile rate of force development (RFD), Impulse, and relative RFD (rRFD) during the initial phase of contraction (100ms time interval relative to onset of contraction). Prior to disuse, marked age-related differences (p<0.05) were observed in isometric and dynamic muscle strength (~35%) as well as in RFD and Impulse (~39%). Following disuse, young and old individuals experienced comparable decrements (p<0.05) in isometric strength (~9%), slow dynamic strength (~13%), and RFD and Impulse (~19%), whereas old individuals only experienced decrements (p<0.05) in moderate dynamic strength (12%) and rRFD (~17%). Following recovery, all measures of mechanical muscle function were restored in young individuals compared to pre-disuse values, while isometric, slow and moderate dynamic muscle strength remained suppressed (p<0.05) in old individuals (~8%) along with a tendency to suppressed RFD100 (p=0.068). In conclusion, 4days of lower limb disuse led to marked decrements in knee extensor mechanical muscle function in both young and old individuals, yet with greater decrements observed in moderate dynamic strength and rapid muscle force capacity in old individuals. While 7days of recovery - including free ambulation, one test session and a single session of strength training - was sufficient to restore mechanical muscle function in young individuals, old individuals appeared to have an impaired ability to fully recover as evidenced by suppressed values of isometric and dynamic muscle strength and rapid muscle force capacity. copy; 2014 Elsevier Inc.
KW - Adult
KW - Aged
KW - Aging
KW - Humans
KW - Immobilization
KW - Male
KW - Muscle Fibers, Skeletal
KW - Muscle Strength
KW - Muscle, Skeletal
KW - Myosin Heavy Chains
U2 - 10.1016/j.exger.2014.01.012
DO - 10.1016/j.exger.2014.01.012
M3 - Journal article
C2 - 24447828
SN - 0531-5565
VL - 52
SP - 1
EP - 8
JO - Experimental Gerontology
JF - Experimental Gerontology
ER -