INTRODUCTION: In short sprinting events like 100m race, performance at the starting block (SB) phase has a critical importance to the final outcome. Among different variables mentioned as critical of SB performance, normalized average horizontal power (NAHP) was identified as the most appropriate measure of performance [1]. This indicates that the athletes ability to produce horizontal power (HP) in a short period of time is a decisive factor in this phase of race. Thus, it is of great interest for strength and conditioning coaches who work with sprinters to understand the associations between athletes SB and their lower limbs strength and power qualities. We aim to understand the relationship between SB performance of elite male sprinters and their lower-body dynamic strength index (DSI). METHODS: Eleven male elite sprinters, (age 23.5 ± 2.9 years; height 1.82 ± 0.04m; body mass 76.8 ± 5.9kg; 100m PB, 10.56 ± 0.27s), performed 3 maximal 10m sprints start on an indoor track, from instrumented SB (Kistler Instruments AG. Winterthur. Switzerland), sampling at 1000 Hz. Block performance was quantified trough NAHP as described by Bezodis et al. [1], where the HP was averaged over the duration of the block phase and normalized to sprinters` body mass and leg length. The best NAHP obtained over 3 trials were used for analysis. To determine DSI, all sprinters performed 3 trials of isometric mid-thigh pulls (IMTP) (isometric task) and countermovement jumps (CMJ) (dynamic task) on a homemade force platform (Shear Beam Load Cells - Flintec BK2) and connected to an A/D converter (MP100 - Biopac Systems Inc. 16 bits) with a sampling rate of 1000 Hz. Best trails were used for analysis. Vertical ground reaction peak force (PF) attained during CMJ was divided by the PF attained in the IMTP to obtain the DSI, as described by Comfort et al [2]. Pearson`s correlation coefficients (r) were used to test the relationship between dependent variables. A statistical significance was set at a= 0.05. RESULTS: NAHP was correlated with the block velocity (r =0.60; P = 0.03). Furthermore, a very large significant correlation was identified between the NAHP and DSI (r = 0.85). A very large significant correlation was also observed between NAHP and CMJ force (r = 0.86). No significant associations were observed between NAHP and IMTP force (r = -0.26; P= 0.220). CONCLUSION: The main conclusion was that NAHP has strong associations with muscle power indicators, measured through CMJ and DSI. These results indicated that DSI and CMJ can be used as indicators of SB performance, in elite male sprinters. These results also highlighted the importance of high-power capacities for a successful sprint start. Thus, the sprinters` strength and power qualities regularly monitored through DSI are very important and determinant to individualize strength-training programs and optimize training stimulus for overall performance improvement.
© Copyright 2022 27th Annual Congress of the European College of Sport Science (ECSS), Sevilla, 30. Aug - 2. Sep 2022. Published by Faculty of Sport Science - Universidad Pablo de Olavide. All rights reserved.