Influence of aerobic fitness status on the power output decrement during repeated sprint running in females.

Background: This study examined the influence of two aerobic fitness indices (VO2max and [%4mM] i.e. the relative intensity [%VO2max] corresponding to a blood lactate concentration of 4 mmol·L^-1) on the recovery of power output during repeated sprinting.

Methods: Thirty female team players (age: 21.9 [2.9] y, body mass: 61.7 [5.4] kg, mean [standard deviation, SD]) took part in the study. VO2max and %4mM were assessed, and participants were divided into two groups in a cross-sectional design [well-trained (N.=15) or moderately trained (N.=15)] according to either VO2max (53.6 [3.4] vs. 47.6 [2.4] mL∙kg∙min^-1, P<0.001) or %4mM (86.7 [3.8] vs. 77.9 [4.1] %, P<0.001). Participants performed two 30 s sprints interspersed with 2 min of rest on a non-motorized treadmill. Blood samples were taken at rest, pre- and immediately post-sprinting for lactate, pH, ammonia, and plasma volume determination.

Results: When groups were separated according to %4mM, well-trained participants demonstrated superior recovery of peak and mean power output (PPO: 86.2 [10.3] vs. 74.5 [6.8] %, P<0.001; MPO30: 84.0 [7.8], vs. 77.1 [5.2] %, P<0.001), respectively]. When groups were separated according to VO2max, there were no differences in the recovery of PPO (82.8 [10.1] vs. 77.7 [10.5] %, P=0.188) and MPO30: (82.6 [6.5] vs. 78.9 [8.1] %, P=0.186). Blood metabolic responses were similar in all conditions (P=0.220-0.604).

Conclusions: The results suggest that %4mM is the most important aerobic fitness index for power output recovery during repeated sprint running.