Anthropometry-driven block setting improves starting block performance in sprinters

Abstract

This study tested the effect of two block setting conditions i.e., the usual block setting [US] and an anthropometry-driven block setting [AS] on the kinematic and kinetic parameters of the sprint start. Furthermore, we verified whether this effect is influenced by the relative lengths of the sprinter’s trunk and lower limbs i.e., the Cormic Index by subdividing sprinters into brachycormic, metricormic and macrocormic groups. Forty-two sprinters performed 6 maximal-effort 10 m sprints using the US and AS conditions. Dynamometric starting blocks measured forces generated by the sprinters. The times at 5 m and 10 m in the sprint trials were measured with photocells. Results showed that the anteroposterior block distances were significantly different between the two conditions (P<0.001). Across the sample, the horizontal block velocity, the rear peak force, the rear force impulse, the total force impulse, the horizontal block power, the ratio of horizontal to resultant impulse in the rear block, the first and second step lengths and the times at 5 m and 10 m improved in AS vs. US (P values from 0.05 to 0.001). Considering the interaction between the block setting condition and the Cormic Index, the rear peak force and the rear force impulse were significantly increased in the metricormic and brachycormic groups (P≤0.001) and the metricormic group (P<0.001), respectively. Kinetic variables in the rear block and the difference (Delta) in the front block/starting line distance between US and AS were related with each other (Adjusted R 2 values from 0.07 to 0.36). In conclusion, AS was associated with improvement in the kinematic and kinetic parameters of the sprint start performance vs. US; however, AS is apparently best suited for metricormic sprinters. Further work is needed to verify how the sprint start kinetic and kinematic parameters are related to the front block/starting line distance and whether a block setting driven by the sprinter’s Cormic Index is able to improve sprint start performance.

Biomechanical Performance Factors in the Track and Field Sprint Start: A Systematic Review

“…Fifteen studies [ 2 , 3 , 10 , 11 , 12 , 17 , 20 , 21 , 23 , 25 , 33 , 34 , 35 , 36 , 37 ] focused specifically on the block phase, 18 studies [ 1 , 4 , 5 , 6 , 7 , 8 , 13 , 14 , 15 , 16 , 18 , 19 , 24 , 38 , 39 , 40 , 41 , 42 ] on the block phase and, at least one of the subsequent two flight and stance phases, and 3 studies [ 9 , 22 , 43 ] on the initial acceleration (the first and/or the second step). A summary of all the individual studies reviewed is presented in Table 1 .…”

“…Study purposes included evaluation of specific block start and initial acceleration variables and their influence on block performance (14 studies) [ 2 , 3 , 4 , 6 , 10 , 11 , 14 , 18 , 23 , 24 , 33 , 36 , 40 , 43 ]; analysis of different “set” position or block configurations (11 studies): location [ 20 ] and modulation [ 35 ] of center of pressure (COP) on the starting block surface, different block spacing [ 8 , 12 , 37 ] and widened conditions [ 21 ], different block plate obliquities [ 19 , 25 , 34 ], changed “set” position knee angles [ 41 ] and block pre-tension [ 17 ]; and comparisons between sprinters of different performance levels, despite the subjectivity associated with the descriptor of the performance level of the athletes (11 studies) [ 1 , 5 , 7 , 9 , 13 , 15 , 16 , 22 , 38 , 39 , 42 ]. The ambiguity in the performance level descriptors includes categories such as: elite vs. sub-elite or well-trained [ 7 , 16 , 22 ], world-class vs. elite [ 38 ], faster vs. slower [ 5 ], adult well-trained vs. trained [ 9 , 15 , 42 ]; elite or well-trained senior vs. junior academy, elite junior, U18 or young well-trained […”

“…Twenty-one studies evaluated kinetic variables from blocks start placed on force platforms (12 studies) [ 5 , 10 , 17 , 18 , 19 , 20 , 21 , 23 , 33 , 35 , 39 , 42 ] or instrumented starting blocks sensors (9 studies) [ 1 , 4 , 11 , 12 , 13 , 16 , 24 , 25 , 34 ]. Twelve studies [ 4 , 6 , 9 , 14 , 15 , 18 , 19 , 22 , 24 , 39 , 42 , 43 ] used a large variety of force platforms arrangements to analyze the dynamic characteristics of the first steps of the initial acceleration.…”

“…Concerning kinematic variables, a bi-dimensional analysis, including one or two high-speed digital cameras, was applied in 9 studies [ 3 , 12 , 13 , 18 , 19 , 25 , 34 , 37 , 40 ], and a 3D kinematic analysis, including 3 [ 38 ], 6 [ 16 ], or 8 or more cameras [ 5 , 6 , 7 , 8 , 9 , 21 , 24 , 36 , 41 ] was applied in 11 studies.…”

“…Given the importance of the sprint start, a new body of research has emerged in the past two decades that involved advanced technologies, high-precision methods, and sprinters of a higher performance level. For this reason, several technical (kinematic) and dynamic (kinetic) aspects are currently identified as determinant factors for starting block phase and initial sprint acceleration performances [ 1 , 4 , 6 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. However, the concepts, outcomes, and findings between studies are sometimes inconsistent and difficult to interpret and conclude from.…”