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

Abstract

28This study compared force-time characteristics and muscle activity between the isometric squat 29 (ISQ) and mid-thigh pull (IMTP) in both bilateral (ISQ BI and IMTP BI ) and unilateral (ISQ UNI and 30 IMTP UNI ) stance. Peak force (PF), rate-of-force (RFD) (e.g. 0-300ms) and EMG of the 31 multifidus, erector spinae (ES), gluteus maximus (GM), biceps femoris (BF), semitendinosus 32 (ST), vastus medialis (VM), vastus lateralis (VL) and soleus were recorded in ten recreationally 33 trained males. PF was significantly greater during the ISQ BI vs. IMTP BI (p=0.016, ES=1.08) 34 but not in the unilateral test mode although effects remained moderate (ES=0.62). A trend 35 indicated heightened RFD 300ms (p = 0.083; ES=0.81) during the IMTP BI vs. the ISQ BI, but these 36 effects were smaller in the unilateral test (ES = 0.51). Greater (p<0.0001) EMG for VL 37 (ES=1.00-1.13) and VM were recorded during the ISQ compared to IMTP modes in both 38 modes (ES = 0.97 -1.18). Greater BF EMG (p = 0.030, ES = 0.31) was shown in IMTP BI vs. 39ISQ BI and these effects were stronger in the unilateral modes (p = < 0.05; ES = 0.81 -0.83). 40 Significantly greater ST activation was shown in both IMTP UNI (p < 0.05; ES = 0.69-0.76) and 41 IMTP BI (p < 0.001; ES = 1.08). These findings indicate that ISQ results in elevated PF, whereas, 42 RFD is heightened during the IMTP and these differences are more pronounced in bilateral 43 modes. Greater activation of the quadriceps and hamstring muscles are expected in ISQ and 44 IMPT respectively. 45 46 Keywords: isometric strength; rate of force development; unilateral and bilateral 47

Influence of Isometric and Dynamic Fatiguing Protocols on Dynamic Strength Index

“…Although the main agonist muscles for both tasks were the same, the differing muscle activations between CMJ and IMTP could underlie our observations. For instance, vastus medialis was reported to exhibit ~83.5% maximal voluntary activity during IMTP [30], while the values can be much higher (~150-190%) in CMJ [31]. In addition, CMJ involves an eccentric and a concentric contraction, and stretch-shortening cycle, and is partially underpinned by different mechanisms than isometric force production (e.g., musculotendinous stiffness [32] and rate of force development [33]).…”

Adjunctive hiking bouts during 8 weeks regular sailing training improves cardiorespiratory and muscular responses during hiking emulation in highly trained sailors

“…Surface electromyography (sEMG) signals underwent signal processing, including low-pass filtering at 400 Hz and high-pass filtering at 20 Hz. Subsequently, sEMG signals obtained from the middle minute of each bout during IRT and the MVC test signals were normalized to a 1000 ms window(Silva et al, 2020). The muscle root mean square (RMS) during the test was normalized according to its own MVC to obtain RMS (%MVC) as an expression of motor unit recruitment and mean power frequency (MPF) as an expression of muscle activation frequency and fatigue development(Coburn et al, 2005).…”