title: Skeletal muscle fatigue, strength, and quality in the elderly: the Health ABC Study.
abstract: We examined the muscle fatigue characteristics in older men and women and determined whether these were related to the size, strength, or quality of muscle. A total of 1,512 men and women aged 70-79 yr from the Health, Aging, and Body Composition Study participated in this study. Muscle cross-sectional area and attenuation were determined with computed tomography. Skeletal muscle fatigue and strength (peak torque) of the knee extensors and flexors were measured using isokinetic dynamometry. Men were more fatigue resistant than women for both knee extension (fatigue index: 70.4 +/- 15.3 vs. 66.9 +/- 14.3%; P < 0.05) and knee flexion (67.9 +/- 16.4 vs. 64.9 +/- 17.6%; P < 0.05). Peak torque and muscle quality (specific torque) were higher in men than women for knee extension (99.6 +/- 28.2 vs. 63.0 +/- 16.8 N x m and 1.62 +/- 0.43 vs. 1.51 +/- 0.39 N x m/cm2; both P < 0.05) and for knee flexion (74.0 +/- 26.4 vs. 49.6 +/- 15.9 N x m and 2.47 +/- 1.29 vs. 2.22 +/- 0.78 N x m/cm2; both P < 0.05). Total work and power output was greater in men compared with women for both the quadriceps (1,353 +/- 451 vs. 832 +/- 264 J and 87.7 +/- 33.5 vs. 53.3 +/- 19.2 W; both P < 0.05) and the hamstrings (741 +/- 244 vs. 510 +/- 141 J and 35.4 +/- 16.0 vs. 23.7 +/- 10.2 W; both P < 0.05). In both genders, the quadriceps was able to perform more work with greater power compared with the hamstrings. Those who were stronger actually had greater fatigue after adjusting for age, race, physical activity, and total body fat. In conclusion, older men were more fatigue resistant than women, although in both men and women greater fatigue was not related to muscle weakness.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pennsylvania, USA. akatsiar@grecc.umaryland.edu
authors.forename: Andreas
authors.initials: A
authors.lastname: Katsiaras
authors.forename: Anne B
authors.initials: AB
authors.lastname: Newman
authors.forename: Andrea
authors.initials: A
authors.lastname: Kriska
authors.forename: Jennifer
authors.initials: J
authors.lastname: Brach
authors.forename: Shanthi
authors.initials: S
authors.lastname: Krishnaswami
authors.forename: Eleanor
authors.initials: E
authors.lastname: Feingold
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Kritchevsky
authors.forename: Rongling
authors.initials: R
authors.lastname: Li
authors.forename: Tamara B
authors.initials: TB
authors.lastname: Harris
authors.forename: Ann
authors.initials: A
authors.lastname: Schwartz
authors.forename: Bret H
authors.initials: BH
authors.lastname: Goodpaster
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology; D001823:Body Composition / Q000502:physiology; D015331:Cohort Studies; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000502:physiology*; D009929:Organ Size / Q000502:physiology; D010414:Pennsylvania / Q000453:epidemiology; D010809:Physical Fitness / Q000502:physiology; D017678:Sex Distribution; D013714:Tennessee / Q000453:epidemiology