Differences in hamstring muscle stretching of elite field hockey players and normal subjects.

Objectives: To investigate differences in stretching behaviour of hamstring muscles in elite field hockey players and normal subjects.
Methods: 16 normal healthy subjects (group A) and 16 elite field hockey players (group B). Stretching of the hamstrings was performed with a knee extension device. Two successive single stretches (1 and 2) until the maximum stretch tolerance was achieved were applied to each subject twice. Simultaneously range of movement (ROM), passive resistance to stretch (PRS) at 36 degrees ROM, and electromyographic (EMG) activity of the biceps femoris and semitendinosus muscles were recorded.
Results: ROM (p=0.02 for stretch 1; p=0.04 for stretch 2) and PRS (p=0.04 and p=0.03) were significantly higher in group B, as compared to group A. The EMG activity of the biceps femoris (p=0.02 for stretch 1; p=0.3 for stretch 2) and semitendinosus (p=0.03 and p=0.11) were significantly higher in group B only for stretch 1. From stretch 1 to 2, a significant increase in ROM was observed in both group A (p=0.002) and group B (p=0.0003), as well as a significant decrease of PRS (p=0.0002; p=0.002). EMG activity only showed a significant decrease in group B (biceps p=0.03;semitendinosus p=0.01), but not in group A (p=0.6; p=0.06). The EMG activity sets in when the subjects begin to perceptive pain in the stretched muscles.
Conclusions: Significant differences exist. in the stretching behaviour of elite field hockey players and non-athletes. ROM, PRS and EMG activity are higher in athletes. Implications for treatment should be considered, but recommendations cannot be made on the basis of this study yet.