The temporal activation between the DL and SLDL for the BF, LM, MG, and AT muscles demonstrated similar patterns.
The key findings of this study were the differences in RMS for the VL and MG muscles between the DL and SLDL exercises.
The VL RMS during the SLDL showed a constant activity during the descent phase of the movement (between -80[degrees] and 0[degrees]).
The MG activity during the DL and SLDL exercises increased slightly during the ascent phase.
The behavior of the BF during the DL and the SLDL in ascent and descent phases were similar and may be attributed to its role during both flexion (descent phase) and extension (ascent phase) of the hip joint during the exercise movement.
This hypothesis indicated that the single-joint exercise such as the SLDL may provide an increase in hamstring muscle activity.
The LM activation during the DL and the SLDL may be characterized as a normal pattern of muscle activity, since little variation was showed during the ascent and descent phases of the movements.
The AT muscle activity remained constant at a low intensity during the DL and SLDL.
However, in the current study all subjects had at least 2 yrs of resistance training experience with the DL and SLDL exercises.
However, the MG muscle showed higher muscle activation during the SLDL than the DL.