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Isokinetic testing is often used to evaluate the effect of different types of interventions and also to interpret whether an individual is ready to return to physical activity. However, limited research exists concerning the suitability of evaluating the effect of isotonic training using isokinetic testing. The aim with this study was to assess the relation between the development of force during isokinetic and isotonic concentric maximal contractions. Fifty subjects (24 women and 26 men) performed maximal concentric isokinetic and isotonic elbow flexion. The isokinetic tests were performed in an isokinetic dynamometer and the isotonic tests in a pulley apparatus. The relationship between the isokinetic values (peak value and mean force value) and the isotonic values (1RM) was modeled by linear regression analysis. There was a significant linear correlation between both the isokinetic values and the isotonic value that explained 89% (peak) and 88% (mean) of the variation. From the linear regression analysis, two different formulas were derived to estimate the prediction of the isokinetic values. The significant relation between isokinetic and isotonic measures means that it may be possible to evaluate the effects of isotonic training by using an isokinetic dynamometer. However, there was a large variation around the predicted isokinetic values that has to be considered. It is important to point out that the results of this study are applicable only on healthy young men and women with similar strength as our subjects. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop a new method of measuring maximal isometric strength, using an isoinertial-based weight machine. The aim was also to investigate the reliability of the isometric strength test and the dynamic one-repetition maximum (1 RM) test in women and men. Healthy recreational weight trainers (15 women and 15 men) were tested firstly for maximal isometric strength and secondly for 1 RM-strength using an isoinertial-based (gym) knee-extension weight machine. The isometric test was carried out with the subject performing a muscle action that dislodged a particular test weight (within 5 s) and, as a result, a weighted rope fell out of the weight stack and the trial was regarded as successful. The test was repeated with increments of weight until failure. Intraclass correlation coefficients (ICC) were used to assess test–retest reliability. High ICCs (>0.90) were found for both the isometric and the 1 RM-strength tests, in both women and men. In conclusion, our new clinical test is a reliable tool for healthy, relatively strong subjects for the establishment of maximal isometric strength using an isoinertial-based weight machine. The test can be used by physical therapists, athletic trainers and strength and conditioning coaches in clinical practice, working with strength training and rehabilitation. [ABSTRACT FROM AUTHOR]