Faculty Collaboration Database

Mechanisms for the age-related increase in fatigability of the knee extensors in old and very old adults. J Appl Physiol (1985) 2018 Jul 01;125(1):146-158

Date

03/02/2018

Pubmed ID

29494293

Pubmed Central ID

PMC6086970

DOI

10.1152/japplphysiol.01141.2017

Scopus ID

2-s2.0-85051059800 (requires institutional sign-in at Scopus site)   36 Citations

Abstract

The mechanisms for the age-related increase in fatigability during high-velocity contractions in old and very old adults (≥80 yr) are unresolved. Moreover, whether the increased fatigability with advancing age and the underlying mechanisms differ between men and women is not known. The purpose of this study was to quantify the fatigability of knee extensor muscles and identify the mechanisms of fatigue in 30 young (22.6 ± 0.4 yr; 15 men), 62 old (70.5 ± 0.7 yr; 33 men), and 12 very old (86.0 ± 1.3 yr; 6 men) men and women elicited by high-velocity concentric contractions. Participants performed 80 maximal velocity contractions (1 contraction per 3 s) with a load equivalent to 20% of the maximum voluntary isometric contraction. Voluntary activation and contractile properties were quantified before and immediately following exercise (<10 s) using transcranial magnetic stimulation and electrical stimulation. Absolute mechanical power output was 97 and 217% higher in the young compared with old and very old adults, respectively. Fatigability (reductions in power) progressively increased across age groups, with a power loss of 17% in young, 31% in old, and 44% in very old adults. There were no sex differences in fatigability among any of the age groups. The age-related increase in power loss was strongly associated with changes in the involuntary twitch amplitude ( r = 0.75, P < 0.001). These data suggest that the age-related increased power loss during high-velocity fatiguing exercise is unaffected by biological sex and determined primarily by mechanisms that disrupt excitation contraction coupling and/or cross-bridge function. NEW & NOTEWORTHY We show that aging of the neuromuscular system results in an increase in fatigability of the knee extensors during high-velocity exercise that is more pronounced in very old adults (≥80 yr) and occurs similarly in men and women. Importantly, the age-related increase in power loss was strongly associated with the changes in the electrically evoked contractile properties suggesting that the increased fatigability with aging is determined primarily by mechanisms within the muscle for both sexes.

Author List

Sundberg CW, Kuplic A, Hassanlouei H, Hunter SK

Author

Chrisopher Sundberg in the CTSI department at Medical College of Wisconsin - CTSI

MESH terms used to index this publication - Major topics in bold

Adult
Age Factors
Aged
Aged, 80 and over
Electric Stimulation
Electromyography
Female
Humans
Isometric Contraction
Knee
Knee Joint
Male
Muscle Contraction
Muscle Fatigue
Muscle Strength
Muscle, Skeletal
Sex Characteristics
Sex Factors
Torque
Transcranial Magnetic Stimulation
Young Adult