Effects of magnets on concentric and eccentric isokinetic force production of the quadriceps group

The purpose of this study was to determine the effects of magnets on concentric and eccentric isokinetic peak and average force production of the dominant knee extensor musculature. All subjects were randomly assessed via isokinetic dynamometry (KinCom 500H, Chattecx Corp.) for concentric and eccentric peak and average force production of the quadriceps in the conditions of magnet, placebo magnet, and control (no magnet). Subjects were assessed at test velocities of 60 and 120 degrees /s. Twenty-one subjects (age = 24.2 + 5.1 yrs, ht = 174.6 + 8.2 cm, wt = 73 + 6.9 kg) voluntarily participated in thestudy. Subjects were excluded if they reported a history of knee surgery or sustained a knee injury within the past six months. Two three-way MANOVA's (velocity x mode x treatment) were used to determine differences between variables. MANOVA revealed significant differences between test velocities (p < 0.001) and mode of contraction (p < 0.05) for peak force production and significant differences between test velocities (p < 0.05) and mode of contraction (p < 0.001) for average force production. MANOVA revealed a significant difference between testing conditions for average force production (p, < 0.05). However, Tukey's post-hoc analysis found no significant difference between conditions. Based on the results of this study, application of a magnetic pad to the quadriceps muscles does not appear to increase acute force production. Further research is needed to critically evaluate other purported effects of magnetotherapy.