Reference Values for Concentric Knee Isokinetic Strength and Power in Nonathletic Men and Women from 20 to 80 Years Old

Abstract

Study Design: A prospective, controlled, randomized study. Objective: To establish reference values for prediction of concentric isokinetic knee strength and power in a sample of nonathletic men and women. Background: Adequate interpretation of knee isokinetic strength and power relies on a representative frame of reference. However, none of the most widely cited prediction studies used a randomly selected sample of nonathletic subjects, therefore limiting the clinical application of these studies.Methods and Measures: We evaluated the concentric right and left knee extensor and flexor peak torque, total work, set total work, average power, and torque acceleration energy (Cybex 6000 System) in 96 healthy subjects (45 men and 51 women, aged 20 to 801, randomly selected from more than 8000 individuals. Results: By stepwise regression analysis, we found that gender, age, weight, height, and regular physical activity explained up to 84% of the variability of the dependent variables: a set of linear prediction equations for strength (at 60' 1s) and power (at 300°/s) is provided. Conclusions: Results from this study might provide a clinically useful frame of reference for interpretation of concentric isokinetic knee strength and power in nonathletic men and women.I Orthop Sports Phys 7her 1999;29:116-126.

Study of differences in peripheral muscle strength of lean versus obese women: an allometric approach

“…Moreover, the larger FFM should be responsible for larger absolute strength values in the quadriceps and hamstrings. 5,6 Absolute¯exion strength of the best knee, however, is comparable in both groups. But, when corrected for FFM, again extension strength is slightly (6 ± 7%), but signi®cantly lower in obese women compared to the lean and kneē exion strength is even up to 18 ± 20% lower.…”

“…However, as muscle mass has been found to be the major determinant of the age and gender related differences in skeletal muscle strength in non-obese subjects, strength measures should be corrected for fat-free mass. 5,6 This has also been pointed out in studies using a handgrip dynamometer. 7,14,15 Strength comparisons between groups can be made by using simple ratio standards, that is strength measures divided by fat-free mass.…”

“…5 Thus, considering the transport of the larger body mass in obesity, the quadriceps muscle (but not the hamstrings) should be stronger due to a training effect of the weight bearing activities. Moreover, the larger FFM should be responsible for larger absolute strength values in the quadriceps and hamstrings.…”

“…Furthermore, experimental groups should be controlled for height, as height has also been pointed out to be a determinant of handgrip 15 and isokinetic muscle strength. 5,22 To our knowledge, until now no studies have been performed controlling for all of these variables.…”

“…Additionally, the lean and obese subjects should be matched for age and physical activity, as aging 5,15,21 and low levels of daily physical activity 4,5,15 tend to impair muscle strength. Furthermore, experimental groups should be controlled for height, as height has also been pointed out to be a determinant of handgrip 15 and isokinetic muscle strength.…”