TY - JOUR
T1 - Age-related changes in the rate of muscle activation and rapid force characteristics
AU - Thompson, Brennan J.
AU - Ryan, Eric D.
AU - Herda, Trent J.
AU - Costa, Pablo B.
AU - Herda, Ashley A.
AU - Cramer, Joel T.
N1 - Funding Information:
Acknowledgments This work was supported in part by the National Strength and Conditioning Foundation. Drs. Thompson, Ryan, Herda, and Costa have no relationships to disclose. Dr. Cramer is the principal investigator or co-investigator of current research or service agreements at the University of Nebraska-Lincoln with Rock Creek Pharmaceuticals, Abbott Nutrition, General Nutrition Center, and Stepan Lipid Nutrition.
PY - 2014/4
Y1 - 2014/4
N2 - Declines in muscle size and strength are commonly reported as a consequence of aging; however, few studies have investigated the influence of aging on the rate of muscle activation and rapid force characteristics across the lifespan. This study aims to investigate the effects of aging on the rate of muscle activation and rapid force characteristics of the plantar flexors. Plantar flexion peak force (PF), absolute (peak, 50, and 100-200 ms), and relative (10 %, 30 %, and 50 %) rate of force development (RFD), the rapid to maximal force ratio (RFD/PF), and the rate of electromyography rise (RER) were examined during an isometric maximal voluntary contraction (MVC) in young (age∈= ∈22∈±∈2 years), middle-aged (43∈±∈2 years), and old (69∈±∈5 years) men. The old men exhibited lower PF (30.7 % and 27.6 % lower, respectively) and absolute (24.4-55.1 %) and relative (16.4-28.9 %) RFD values compared to the young and middle-aged men (P∈0.03). RER values were similar between the young and old men (P∈∈0.30); however, RER values were greater for the middle-aged men when compared to the young and old men for the soleus (P∈;lt0.01) and the old men for the medial gastrocnemius (P∈;∈0.02). Likewise, RFD/PF ratios were similar between young and old men (P∈∈0.26); however, these ratios were greater for the middle-aged men at early (P∈0.03), but not later (P∈∈0.10), time intervals. The lower PF and absolute and relative RFD values for the old men may contribute to the increased functional limitations often observed in older adults. Interestingly, higher rates of muscle activation and greater early RFD/PF ratios in middle-aged men may be a reflection of physiological alterations in the neuromuscular system occurring in the fifth decade.
AB - Declines in muscle size and strength are commonly reported as a consequence of aging; however, few studies have investigated the influence of aging on the rate of muscle activation and rapid force characteristics across the lifespan. This study aims to investigate the effects of aging on the rate of muscle activation and rapid force characteristics of the plantar flexors. Plantar flexion peak force (PF), absolute (peak, 50, and 100-200 ms), and relative (10 %, 30 %, and 50 %) rate of force development (RFD), the rapid to maximal force ratio (RFD/PF), and the rate of electromyography rise (RER) were examined during an isometric maximal voluntary contraction (MVC) in young (age∈= ∈22∈±∈2 years), middle-aged (43∈±∈2 years), and old (69∈±∈5 years) men. The old men exhibited lower PF (30.7 % and 27.6 % lower, respectively) and absolute (24.4-55.1 %) and relative (16.4-28.9 %) RFD values compared to the young and middle-aged men (P∈0.03). RER values were similar between the young and old men (P∈∈0.30); however, RER values were greater for the middle-aged men when compared to the young and old men for the soleus (P∈;lt0.01) and the old men for the medial gastrocnemius (P∈;∈0.02). Likewise, RFD/PF ratios were similar between young and old men (P∈∈0.26); however, these ratios were greater for the middle-aged men at early (P∈0.03), but not later (P∈∈0.10), time intervals. The lower PF and absolute and relative RFD values for the old men may contribute to the increased functional limitations often observed in older adults. Interestingly, higher rates of muscle activation and greater early RFD/PF ratios in middle-aged men may be a reflection of physiological alterations in the neuromuscular system occurring in the fifth decade.
KW - Elderly
KW - Neuromuscular activation
KW - Plantar flexors
KW - Rate of EMG rise
KW - Rate of force development
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U2 - 10.1007/s11357-013-9605-0
DO - 10.1007/s11357-013-9605-0
M3 - Article
C2 - 24338233
AN - SCOPUS:84898622506
SN - 0161-9152
VL - 36
SP - 839
EP - 849
JO - AGE
JF - AGE
IS - 2
ER -