Optimizing athlete assessment of maximal force and rate of development A comparison of the isometric squat and mid-thigh pull

This study compared force-time characteristics and muscle activity between the isometric squat (ISQ) and mid-thigh pull (IMTP) in both bilateral (ISQBI and IMTPBI) and unilateral (ISQUNI and IMTPUNI) stance. Peak force (PF), rate-of-force (RFD) (e.g. 0-300ms) and EMG of the multifidus, erector spinae (ES), gluteus maximus (GM), biceps femoris (BF), semitendinosus (ST), vastus medialis (VM), vastus lateralis (VL) and soleus were recorded in ten recreationally trained males. PF was significantly greater during the ISQBI vs. IMTPBI (p=0.016, ES=1.08) but not in the unilateral test mode although effects remained moderate (ES=0.62). A trend indicated heightened RFD300ms (p = 0.083; ES=0.81) during the IMTPBI vs. the ISQBI, but these effects were smaller in the unilateral test (ES = 0.51). Greater (p<0.0001) EMG for VL (ES=1.00-1.13) and VM were recorded during the ISQ compared to IMTP modes in both modes (ES = 0.97 - 1.18). Greater BF EMG (p = 0.030, ES = 0.31) was shown in IMTPBI vs. ISQBI and these effects were stronger in the unilateral modes (p = < 0.05; ES = 0.81 - 0.83). Significantly greater ST activation was shown in both IMTPUNI (p < 0.05; ES = 0.69-0.76) and IMTPBI (p < 0.001; ES = 1.08). These findings indicate that ISQ results in elevated PF, whereas, RFD is heightened during the IMTP and these differences are more pronounced in bilateral modes. Greater activation of the quadriceps and hamstring muscles are expected in ISQ and IMPT respectively.