Changes in Dynamic Strength Index in Response to Strength Training

Abstract

The primary aim of this investigation was to determine the effects of a four-week period of in-season strength training on the dynamic strength index (DSI). Pre and post a four-week period of strength-based training, twenty-four collegiate athletes (age = 19.9 ± 1.3 years; height = 1.70 ± 0.11 m; weight 68.1 ± 11.8 kg) performed three isometric mid-thigh pulls and countermovement jumps to permit the calculation of DSI. T-tests and Cohen’s effect sizes revealed a significant but small (p = 0.009, d = 0.50) decrease in DSI post-training (0.71 ± 0.13 N·N−1) compared to pre-training (0.65 ± 0.11 N·N−1); however, when divided into high and low DSI groups, differential responses were clear. The low DSI group exhibited no significant or meaningful (p = 1.000, d = 0.00) change in DSI pre to post-training (0.56 ± 0.05 N·N−1, 0.56 ± 0.09 N·N−1, respectively), whereas the high DSI group demonstrated a significant and large decrease (p = 0.034, d = 1.29) in DSI pre to post-training (0.85 ± 0.05 N·N−1, 0.74 ± 0.11 N·N−1, respectively), resulting in a significant and moderate difference (p = 0.034, d = 1.29) in the change in DSI between groups. These results demonstrate that DSI decreases in response to strength training, as expected, due to an increase in isometric mid-thigh pull peak force, with minimal change in dynamic (countermovement jump) peak force.

Effect of additional Nordic hamstring exercise or sprint training on the modifiable risk factors of hamstring strain injuries and performance

“…Each resistance training session consisted of three lower limb exercises, where the training volume remained constant across the training intervention, whilst intensity was manipulated ( Table 1 ). This is consistent with a previous intervention observing changes in athletic performance with the addition of a unilateral exercise within the present study [ 34 ]. The loads for all exercises were based of self-identified recently achieved training maxes, the power clean and mid-thigh pulls were based of the subjects one repetition max (1RM) power clean, and the loads prescribed for the remaining exercises were based one predicted 1RM loads based of 3 or 5RM performances in previous phases of training.…”

Strong, Fast, Fit, Lean, and Safe: A Positional Comparison of Physical and Physiological Qualities Within the 2020 Australian Women's Rugby League Team

“…Whole-body strength was assessed during an isometric midthigh pull (IMTP) using the ForceDecks and the commercially available frame (Vald Performance Pty Ltd.) in line with previously published research (12,22,23). The mid-thigh position was determined for each player before testing by marking the middle point between the knee and hip joints (Seca, Hamberg, Germany) and the height of the barbell was adjusted on the frame to the mid-thigh.…”

The Benefits of Strength Training on Musculoskeletal System Health: Practical Applications for Interdisciplinary Care

“…The benefits of increasing muscular strength include a positive influence on rate of force development (RFD) and power [1,3,4], improved jumping [1], sprinting [5] and change of direction (COD) performance [6], greater magnitudes of potentiation [1], and enhanced running economy [7]. Strong evidence supports the notion that maximal strength serves as one of the key foundations for the expression of high power outputs and that improving and maintaining high levels of strength are of utmost importance to best capitalise on these associations [8][9][10][11][12][13].…”