Changes in Dynamic Strength Index in Response to Strength Training

• Main Authors: Paul Comfort (Author), Christopher Thomas (Author), Thomas Dos'Santos (Author), Timothy J. Suchomel (Author), Paul A. Jones (Author), John J. McMahon (Author)
• Format: Book
• Published: MDPI AG, 2018-12-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.

Summary

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 &#177; 1.3 years; height = 1.70 &#177; 0.11 m; weight 68.1 &#177; 11.8 kg) performed three isometric mid-thigh pulls and countermovement jumps to permit the calculation of DSI. T-tests and Cohen&#8217;s effect sizes revealed a significant but small (<i>p</i> = 0.009, <i>d</i> = 0.50) decrease in DSI post-training (0.71 &#177; 0.13 N&#183;N^&#8722;1) compared to pre-training (0.65 &#177; 0.11 N&#183;N^&#8722;1); however, when divided into high and low DSI groups, differential responses were clear. The low DSI group exhibited no significant or meaningful (<i>p</i> = 1.000, <i>d</i> = 0.00) change in DSI pre to post-training (0.56 &#177; 0.05 N&#183;N^&#8722;1, 0.56 &#177; 0.09 N&#183;N^&#8722;1, respectively), whereas the high DSI group demonstrated a significant and large decrease (<i>p</i> = 0.034, <i>d</i> = 1.29) in DSI pre to post-training (0.85 &#177; 0.05 N&#183;N^&#8722;1, 0.74 &#177; 0.11 N&#183;N^&#8722;1, respectively), resulting in a significant and moderate difference (<i>p</i> = 0.034, <i>d</i> = 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.

Item Description

2075-4663
10.3390/sports6040176