Kinematics of transition during human accelerated sprinting

Abstract

This study investigated kinematics of human accelerated sprinting through 50 m and examined whether there is transition and changes in acceleration strategies during the entire acceleration phase. Twelve male sprinters performed a 60-m sprint, during which step-to-step kinematics were captured using 60 infrared cameras. To detect the transition during the acceleration phase, the mean height of the whole-body centre of gravity (CG) during the support phase was adopted as a measure. Detection methods found two transitions during the entire acceleration phase of maximal sprinting, and the acceleration phase could thus be divided into initial, middle, and final sections. Discriminable kinematic changes were found when the sprinters crossed the detected first transition—the foot contacting the ground in front of the CG, the knee-joint starting to flex during the support phase, terminating an increase in step frequency—and second transition—the termination of changes in body postures and the start of a slight decrease in the intensity of hip-joint movements, thus validating the employed methods. In each acceleration section, different contributions of lower-extremity segments to increase in the CG forward velocity—thigh and shank for the initial section, thigh, shank, and foot for the middle section, shank and foot for the final section—were verified, establishing different acceleration strategies during the entire acceleration phase. In conclusion, there are presumably two transitions during human maximal accelerated sprinting that divide the entire acceleration phase into three sections, and different acceleration strategies represented by the contributions of the segments for running speed are employed.

Acceleration capability in elite sprinters and ground impulse: Push more, brake less?

“…Data were then averaged through three phases: starting-block push-off, entire 40-m sprint, first half of the acceleration (0-20 m section, starting-block push included) and second half of the acceleration (20-40 m section). This 20-m split was chosen in accordance with the "breakpoint" phenomenon presented in detail by Nagahara et al (2014), who showed that a breakpoint in sprint acceleration kinematics occurred around the 20-m mark.…”

Kinematic Characteristics of High Step Frequency Sprinters and Long Step Length Sprinters at Top Speed Phase

“…These distances are diŠer-ent from stance and ‰ight distances using centre of mass (Hay, 1993). However, the diŠerence between the centre of mass and the great trochanter was expected to be small (Nagahara et al, 2014). Moreover, step length had a strong positive correlation with sum of the stance and ‰ight hip distances (r＝0.983, y＝0.975x＋0.053, x: sum of the stance and ‰ight hip distances, y: step length, mean of absolute residual＝0.02 m).…”

On the Importance of “Front-Side Mechanics” in Athletics Sprinting

“…Only a few scientific studies have investigated the kinematics of athletic sprinting based on high-resolution assessments of >6 steps. [14][15][16] However, none of these investigations focused on the relationship between body configuration and performance.…”