Muscle activity during different styles of deep water running and comparison to treadmill running at matched stride frequency.

The purpose of this study was to compare muscle activity during deep water running (DWR) and treadmill running on dry land (TMR) as well as to investigate effect of stride frequency (SF) on muscle activity while using different styles of DWR (high-knee and cross-country styles, DWR-HK and DWR-CC, respectively). Eight subjects participated in this study. The baseline condition consisted of TMR at the preferred stride frequency (PSF). The remaining conditions consisted of DWR-HK and DWR-CC at PSF, PSF-15%, and PSF+15%. Muscle activity was recorded from the rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius. Rectus femoris and biceps femoris muscle activity during DWR-CC-PSF were significantly greater than that of TMR-PSF (P<0.05). However, rectus femoris muscle activity during DWR-HK-PSF was significantly lower than that of TMR-PSF (P<0.05). Gastrocnemius muscle activity during both DWR-HK-PSF and DWR-CC-PSF were significantly lower than that of TMR-PSF (P<0.05). Furthermore, muscle activity from all tested muscles during DWR-HK and DWR-CC increased with increasing SF (P<0.05). These observations indicated that muscle activity is influenced not only by running in the water but also by the style of DWR (DWR-HK, DWR-CC) used.