Content area
Full Text
ABSTRACT. Jennings, C.L., W. Viljoen, J. Durandt, and M.I. Lambert. The reliability of the FitroDyne as a -measure of muscle power. J. Strength Cond. Res. 19(4):859-863.2005.-The FitroDyne is a device that attaches to conventional resistancetraining equipment to measure speed of movement, from which muscle power is calculated. The aim of this study was to quantify the repeatability of the measurement of muscle power with the FitroDyne during squat jump and biceps curl exercises. Thirty male subjects completed 3 trials, each consisting of 6 squat jumps and 6 biceps curls of increasing loads. Upper body and lower body maximum power was predicted from the force-velocity curves derived from the range of weights used for each trial. Maximum power measurements of a squat jump (range, 911-1,673 W) and biceps curl (range, 45-110 W) had intraclass correlation coefficients (ICC) of R = 0.97 (95% CI, 0.95-0.98) and R = 0.97 (95% CI, 0.95-0.98), respectively. The limits of agreement for the squat jump and biceps curl trials were -17 ± 96 W and 0.11 ± 13.90 W, respectively. It may be concluded that muscle power can be measured with a high degree of reliability with the FitroDyne. The limits of agreement need to be considered when data are interpreted.
KEY WORDS, squat jump, biceps curl, peak power, force-velocity relationship
INTRODUCTION
The most common methods of measuring muscle function use isometric, isokinetic, jumping, and resistance-training tests (8). There are numerous ways of quantifying muscle function, ranging from sophisticated laboratory tests to less-precise field tests (6). Although conditions can be well controlled in laboratory tests, the field tests are often more practical, relevant, and sport specific. A test is more useful if it simulates a specific movement pattern that occurs in the sporting activity. Therefore, each testing method has circumstances in which it would be most appropriate to use. These circumstances depend on the cost, the precision of the measurement needed, the requirement for sports specificity, and the practicality of use.
Recently, a device to measure muscle power (FitroDyne; Fitronic, Bratislava, Slovakia) became commercially available, and it has been used in research (2, 3). This device attaches to conventional resistance-training equipment and measures the speed of muscle contraction. Muscle power is calculated from the product of force and speed of...