Electromyographic Comparison Of Squats Using Constant Or Variable Resistance
The aim of the study was to compare the electromyographic activity of vastus lateralis, vastus medialis, rectus femoris and biceps femoris when performing the squat with constant resistance or variable resistance with two or four elastic bands, respectively contributing with a mean of 39% and 73% of the total loads. Nineteen resistance-trained women performed 6 repetition maximum (6-RM) using three different experimental conditions: free weights (FW), free weights + 2 elastic bands (FW+2EB) and free weights + 4 elastic bands (FW+4EB). During analyses, each repetition was divided into six phases; upper (more extended knee), middle and lower phase of the descending and ascending movement. Increased activation in the upper parts of the movement was observed for both variable resistance conditions compared to constant resistance (9–51%, p<0.001–0.050). Further, a dose-response effect of variable resistance was observed in the upper ascending movement, with 4 elastic bands increasing muscle activation more than 2 elastic bands (7 – 28%, p = 0.003–0.007). For the whole movement, a 12% higher activation of the biceps femoris was observed for FW+4EB compared to FW (p = 0.005). There were no differences between the other conditions in any of the muscles (p = 0.077 – 1.000). In conclusion, performing the squat using free weights in combination with elastic bands appears to be preferable compared to free weights alone, and more so with a high contribution from variable resistance to the total load.