Effects of maximal power and the force–velocity profile on sprint acceleration performance according to maturity status and sex

This study aimed to determine whether maturational and sex-related differences in sprint times were accompanied by changes in relative maximal power (<i>P</i>_max), force-velocity profiles (<i>S</i>_FV) and optimal sprint distances (<i>x</i>_opt). Sprint times and continuous velocity-time data were collected using a radar. Inverse dynamics applied to the centre of mass provided accurate estimations of force-velocity relationship parameters (<i>P</i>_max, <i>F</i>₀, <i>v</i>₀, <i>S</i>_FV, <i>x</i>_opt) and technical variables (<i>RF</i>_max, <i>D</i>_RF). Somatic maturity was determined from peak height velocity (PHV). Performance increased with maturation in girls and boys (<i>p</i> < 0.001, <i>d</i> = 0.86‒2.78) accompanied by increases in relative <i>P</i>_max from pre to post-PHV (<i>p</i> < 0.011‒0.001, <i>d</i> = 0.98‒5.20). Increases in relative <i>P</i>_max were predominantly due to more velocity-oriented profiles (<i>p</i> < 0.007‒0.001, <i>d</i> = 0.76‒1.41). <i>x</i>_opt, <i>RF</i>_max and <i>D</i>_RF also increased with maturation (<i>p</i> < 0.030‒0.001, <i>d</i> = 0.87‒3.40). <i>P</i>_max increases in girls and boys throughout maturation enabling them to reduce sprint times. Both girls and boys increased <i>P</i>_max through a shift to more velocity-oriented profiles. However, plateaus in <i>F</i>₀ and <i>RF</i>_max were present from pre-PHV in girls, while boys had slower development from mid-PHV. Improving <i>P</i>_max through increases in <i>F</i>₀ and <i>RF</i>_max, while maintaining a velocity-oriented profile, will likely benefit youth sprint performance. A specific focus on these parameters is necessary from pre-PHV onwards in girls and from mid-PHV in boys.