Well-trained Sprinters Research Articles

3D Kinematic of Bunched, Medium and Elongated Sprint Start

The aim of this study was to test the influence of 3 different horizontal distances between the blocks (bunched, medium and elongated) on the velocity of the centre of mass (VCM) and the kinetic energy (KE) of the body segments and of the whole body. 9 well-trained sprinters performed 4 maximal 10 m sprints. An opto-electronic Motion Analysis® system (12 digital cameras 250 Hz) was used to collect the 3D trajectories of 63 markers during the starting block phase. The results demonstrated that the elongated start, compared to the bunched or medium start, induced an increase of VCM at block clearing (2.89±0.13; 2.76±0.11; 2.84±0.14 m.s - 1) and a decrease of the performance at 5 and 10 m. Both results were explained by a greater pushing time on the blocks in the elongated condition. During the starting block phase, the KE of the whole body was greater in the elongated start (324.3±48.0 J vs. 317.4±57.2 J, bunched and 302.1±53.2 J, medium). This greater KE of the whole body was mainly explained by the KE of the head-trunk segments. Thus, to improve the efficiency of the starting block phase, the athlete must produce greater KE of the head and trunk segments in the shortest time.

Relationship Between Traditional and Ballistic Squat Exercise With Vertical Jumping and Maximal Sprinting

The purpose of this study was to quantify the magnitude of the relationship between vertical jumping and maximal sprinting at different distances with performance in the traditional and ballistic concentric squat exercise in well-trained sprinters. Twenty-one men performed 2 types of barbell squats (ballistic and traditional) across different loads with the aim of determining the maximal peak and average power outputs and 1 repetition maximum (1RM) values. Moreover, vertical jumping (countermovement jump test [CMJ]) and maximal sprints over 10, 20, 30, 40, 60, and 80 m were also assessed. In respect to 1RM in traditional squat, (a) no significant correlation was found with CMJ performance; (b) positive strong relationships (p < 0.01) were obtained with all the power measures obtained during both ballistic and traditional squat exercises (r = 0.53-0.90); (c) negative significant correlations (r = -0.49 to -0.59, p < 0.05) were found with sprint times in all the sprint distances measured when squat strength was expressed as a relative value; however, in the absolute mode, no significant relationships were observed with 10- and 20-m sprint times. No significant relationship was found between 10-m sprint time and relative or absolute power outputs using either ballistic or traditional squat exercises. Sprint time at 20 m was only related to ballistic and traditional squat performance when power values were expressed in relative terms. Moderate significant correlations (r = -0.39 to -0.56, p < 0.05) were observed between sprint times at 30 and 40 m and the absolute/relative power measures attained in both ballistic and traditional squat exercises. Sprint times at 60 and 80 m were mainly related to ballistic squat power outputs. Although correlations can only give insights into associations and not into cause and effect, from this investigation, it can be seen that traditional squat strength has little in common with CMJ performance and that relative 1RM and power outputs for both squat exercises are statistically correlated to most sprint distances underlying the importance of strength and power to sprinting.

Kinematic and Kinetic Comparisons of Elite and Well-Trained Sprinters During Sprint Start

The purpose of this study was to compare the main kinematic, kinetic, and dynamic parameters of elite and well-trained sprinters during the starting block phase and the 2 subsequent steps. Six elite sprinters (10.06-10.43 s/100 m) and 6 well-trained sprinters (11.01-11.80 s/100 m) equipped with 63 passive reflective markers performed 4 maximal 10 m sprint starts on an indoor track. An opto-electronic motion analysis system consisting of 12 digital cameras (250 Hz) was used to record 3D marker trajectories. At the times "on your marks," "set," "clearing the block," and "landing and toe-off of the first and second step," the horizontal position of the center of mass (CM), its velocity (XCM and VCM), and the horizontal position of the rear and front hand (X(Hand_rear) and X(Hand_front)) were calculated. During the pushing phase on the starting block and the 2 first steps, the rate of force development and the impulse (F(impulse)) were also calculated. The main results showed that at each time XCM and VCM were significantly greater in elite sprinters. Moreover, during the pushing phase on the block, the rate of force development and F(impulse) were significantly greater in elite sprinters (respectively, 15,505 +/- 5,397 N.s and 8,459 +/- 3,811 N.s for the rate of force development; 276.2 +/- 36.0 N.s and 215.4 +/- 28.5 N.s for F(impulse), p < or = 0.05). Finally, at the block clearing, elite sprinters showed a greater XHand_rear and X(Hand_front) than well-trained sprinters (respectively, 0.07+/- 0.12 m and -0.27 +/- 0.36 m for X(Hand_rear); 1.00 +/- 0.14 m and 0.52 +/- 0.27 m for X(Hand_front); p < or = 0.05). The muscular strength and arm coordination appear to characterize the efficiency of the sprint start. To improve speed capacities of their athletes, coaches must include in their habitual training sessions of resistance training.

Lower-Limb Mechanics during the Support Phase of Maximum-Velocity Sprint Running

The forces produced by an athlete during the support phase of a sprint run are a vital determinant of the outcome of the performance. The purpose of this study was to improve the understanding of sprint technique in well-trained sprinters through the comprehensive analysis of joint kinetics during the support phase of a maximum-velocity sprint. Four well-trained sprinters performed maximum-effort 60-m sprints. Two-dimensional high-speed video (200 Hz) and ground-reaction force (1000 Hz) data were collected at the 45-m mark. Horizontal velocity, step length, step frequency, and normalized moment, power, and work, via inverse dynamics, were calculated for two trials in each athlete. The hip extensors performed positive work in early stance (normalized value = 0.063 +/- 0.017), and the plantar flexors performed positive work in late stance (normalized value = 0.053 +/- 0.010). The knee extensors played a negligible role in positive work generation throughout stance. In contrast to previous findings, the knee moment did not contribute substantially to power generation during the latter part of the support phase. This may be explained in part by the specific technical requirements of the maximum-velocity phase of the sprint. However, major periods of power generation of the hip extensors in early stance and of the plantar flexors in late stance were observed. The action of the knee joint during the support phase may therefore have been more of a facilitator for the radial transfer of power from the hip through the ankle on to the track.

Plasma LDH and CK activities after 400 m sprinting by well-trained sprint runners.

Blood lactate concentration and the activities of plasma LDH and CK were determined in 13 well-trained middle distance runners after a 400-m sprint. It was found that there is a significant relationship between mean velocity in the 400-m sprint and plasma CK activity (r = -0.56, P less than 0.05), but the mean sprint velocity did not correlate with peak blood lactate concentration (r = -0.09) or plasma LDH activity (r = -0.40). There was a significant negative correlation between mean sprint velocity and H type LDH isozyme activity (r = -0.66, P less than 0.05), and a significant positive correlation with M type LDH isozyme activity (r = 0.66, P less than 0.05). These results suggest that the magnitude of enzyme efflux from tissue into blood may be depressed by training, and that in well-trained sprinters plasma CK and LDH isozyme activities may be better indicators of physical training and/or physical performance than peak blood lactate or plasma LDH activities.