The aim of this study was to evaluate muscle activity during hamstring rehabilitation exercises performed in training machine compared with elastic resistance.
Six women and 13 men aged 28–67 yrs participated in a crossover study. Electromyographic (EMG) activity was recorded in the biceps femoris and the semitendinosus during the concentric and the eccentric phase of hamstring curls performed with TheraBand elastic tubing and Technogym training machines and normalized to maximal voluntary isometric contraction–EMG (normalized EMG). Knee joint angle was measured using electronic inclinometers.
Training machines and elastic resistance showed similar high levels of muscle activity (biceps femoris and semitendinosus peak normalized EMG >80%). EMG during the concentric phase was higher than during the eccentric phase regardless of exercise and muscle. However, compared with machine exercise, slightly lower (P < 0.05) normalized EMG values were observed using elastic resistance at 30- to 50-degree knee joint angle for the semitendinosus and the biceps femoris during the concentric and the eccentric phase, respectively. Perceived loading (Borg CR10) was significantly higher (P < 0.001) during hamstring curl performed with elastic resistance (7.58 ± 0.08) compared with hamstring curl performed in a machine (5.92 ± 0.03).
Hamstring rehabilitation exercise performed with elastic resistance induces similar peak hamstring muscle activity but slightly lower EMG values at more extended knee angles and with higher perceived loading as hamstring curls using training machines.
From the National Research Centre for the Working Environment, Copenhagen, Denmark (MDJ, ES, CHA, LLA); Department of Psychology, Lund University, Lund, Sweden (RP); Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark (MDJ, ES); and Arthroscopic Centre Amager and Gait Analysis Laboratory, Copenhagen University Hospital, Hvidovre, Denmark (MKZ).
All correspondence and requests for reprints should be addressed to: Markus Due Jakobsen, MSc, National Research Centre for the Working Environment, Lersø Parkalle 105, DK-2100 Copenhagen, Denmark.
Supported by a grant from the Danish Working Environment Research Fund (grant no. 48-2010-03) (to L.L.A.).
Financial disclosure statements have been obtained, and no conflicts of interest have been reported by the authors or by any individuals in control of the content of this article.