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Reliability of Maximal Voluntary Muscle Strength and Power Testing in Older Men

Departments of ¹ Biokinesiology and Physical Therapy, ² Preventive Medicine, and ³ Medicine, Keck School of Medicine, University of Southern California, Los Angeles.
⁴ Nutrition, Exercise Physiology and Sarcopenia Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts.

Address correspondence to E. Todd Schroeder, PhD, University of Southern California, Departments of Medicine and Biokinesiology & Physical Therapy, 1540 East Alcazar St., CHP-155, Los Angeles, CA 90089. E-mail: eschroed{at}usc.edu

Background. Maximal voluntary muscle strength (MVMS) and leg power are important measures of physical function in older adults. We hypothesized that performing these measures twice within 7–10 days would demonstrate a >5% increase due to learning and familiarization of the testing procedures.

Methods. Data were collected from three studies in older adult men (60–87 years) and were divided into two cohorts defined by study site and type of exercise equipment. MVMS was assessed in 116 participants using the one-repetition maximum method at two separate study visits for the chest press, latissimus pull-down, leg press, leg flexion, and leg extension exercises along with unilateral leg extension power.

Results. Test–retest scores were not different and did not exceed 0.8 ± 9.0% in Cohort 1 or 2.3 ± 9.8% in Cohort 2, except for leg extension, which improved by 6.6 ± 14.4% (p <.009) and 3.4 ± 6.8% (p <.016), respectively. Repeat tests were closely correlated with initial tests (all p <.001). Pearson correlation coefficients ranged from 0.74 for leg extension power to 0.96 for leg press. Coefficients of variation were <10% (4.2%–9.0%) for all exercises except for leg extension power, which was 15.5%.

Conclusions. Our findings demonstrated that test–retest measures of MVMS and power in older adult men do not differ by more than 2.3% except for leg extension, and have relatively low coefficients of variation using data collected from three studies. Moreover, these findings were similar between two study sites using different equipment, which further supports the reliability of MVMS and power testing in older adult men.