Fig 1.
A. Running velocity measured with the 1080 Sprint device during a 30 m sprint acceleration, and fitted with a mono-exponential. Analyzed data was backward-extrapolated to 0 s using the subsequent equation fit. B. Force and power outputs in the horizontal direction are then computed from center of mass mechanics based on the methods of [13]. C. Force-velocity and power-velocity relationships are plotted based on the data presented in B. and used to compute maximal theoretical force F0, velocity v0, maximal power Pmax and the corresponding optimal velocity vopt = 0.5.v0 [14]. Finally, the slope of the force-velocity relationship (SFv) indicates the force-velocity profile of the athlete (data for a 1.73 m, 95-kg rugby player). Note that the exact same procedures were used with the soccer players, except that the initial raw velocity data were recorded using a radar gun (as in Samozino et al. 2016).
Fig 2.
A. Running velocity measured with the 1080 Sprint device during resisted sprint acceleration, against loads corresponding to unresisted (minimal load of 1-kg), and 25, 50, 75 and 100% BM in a 1.73 m, 95-kg rugby player. B. maximal velocity was averaged for the last 2 s of each sprint and plotted against load to obtain the linear load-velocity profile, from which optimal load (Lopt) and the load that induced a 10% decrease in maximal velocity (L10) were computed. Note that Lopt is produced at optimal velocity vopt = 0.5v0 [14], data described in Fig 1.
Table 1.
Study timeline.
Table 2.
Athlete body-mass, mechanical, technical and performance sprint variables during pre- and post-testing for the L10 and Lopt groups.
Table 3.
Post–pre changes in athlete body-mass, mechanical, technical and performance sprint variables between the L10 and Lopt groups.