Influence of Age on Isometric, Isotonic, and Isokinetic Force Production Characteristics in Men

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Abstract

Background and Purpose:

Most previous studies have focused on the effects of age on muscle performance of a single type of contraction, usually isometric, and usually on only a single muscle group. Instead, we investigated the influence of age on isometric, isotonic, and isokinetic muscle performance in men aged 20-83 years and determined relationships between regional lean body mass and muscle performance.

Methods:

Seventy-five volunteers were placed into designated 10-year age groups: 20-29 (n=13), 30-39 (n=14), 40-49 (n=15), 50-59 (n=10), 60-69 (n=14), and 70+ years (n=9). Muscle performance was characterized by a number of parameters, including strength, time, and rate for maximal voluntary contractions using all 3 contraction types and 4 muscle groups (elbow extensors, elbow flexors, knee extensors, and knee flexors). Measures of lean body mass were obtained by dual energy x-ray absorptiometry.

Results:

There were significant age group differences in maximal force (P < 0.05) for each type of muscle contraction, and in maximal rates of isometric force production (P < 0.05), with declines beginning around 60 years of age. Differences in muscle performance between age groups remained when body composition differences were controlled statistically.

Conclusion:

Chronological age affected performance of both upper and lower extremity muscles, independent of muscle mass, and regardless of contraction type; however, isometric performance was the least affected.

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