The Validity of an Updated Metabolic Power Algorithm Based upon di Prampero's Theoretical Model in Elite Soccer Players.

The aim of this study was to update the metabolic power (MP) algorithm (PV˙O2, W·kg-1) related to the kinematics data (PGPS, W·kg-1) in a soccer-specific performance model. For this aim, seventeen professional (Serie A) male soccer players (V˙O2max 55.7 ± 3.4 mL·min-1·kg-1) performed a 6 min run at 10.29 km·h-1 to determine linear-running energy cost (Cr). On a separate day, thirteen also performed an 8 min soccer-specific intermittent exercise protocol. For both procedures, a portable Cosmed K4b2 gas-analyzer and GPS (10 Hz) was used to assess the energy cost above resting (C). From this aim, the MP was estimated through a newly derived C equation (PGPSn) and compared with both the commonly used (PGPSo) equation and direct measurement (PV˙O2). Both PGPSn and PGPSo correlated with PV˙O2 (r = 0.66, p < 0.05). Estimates of fixed bias were negligible (PGPSn = -0.80 W·kg-1 and PGPSo = -1.59 W·kg-1), and the bounds of the 95% CIs show that they were not statistically significant from 0. Proportional bias estimates were negligible (absolute differences from one being 0.03 W·kg-1 for PGPSn and 0.01 W·kg-1 for PGPSo) and not statistically significant as both 95% CIs span 1. All variables were distributed around the line of unity and resulted in an under- or overestimation of PGPSn, while PGPSo routinely underestimated MP across ranges. Repeated-measures ANOVA showed differences over MP conditions (F1,38 = 16.929 and p < 0.001). Following Bonferroni post hoc test significant differences regarding the MP between PGPSo and PV˙O2/PGPSn (p < 0.001) were established, while no differences were found between PV˙O2 and PGPSn (p = 0.853). The new approach showed it can help the coaches and the soccer trainers to better monitor external training load during the training seasons.

Energetics of best performances in elite kayakers and canoeists.

PURPOSE: The objectives of this study were 1) to validate a new test to determine maximal oxygen uptake (V˙O2max) in kayakers, 2) to calculate the energy cost (Ck) of high-level kayakers and canoeists at submaximal and race speeds, and 3) to correlate individual best performances achieved in practice with those theoretically calculated. These were obtained from the individual relationships Er=f(t) and Emax=f(t), where Er is the metabolic power required to cover the distance in question and Emax is the maximal metabolic power. The time yielding Er=Emax was assumed to yield the best performance time. METHODS: Seventy-four male and female athletes from the Italian national canoe kayak teams participated in this study. A portable metabolic unit was used to determine V˙O2max during an incremental exercise test on the boat. Peak oxygen uptake (V˙O2peak) was also measured in a 2-min test at 100% race speed over 1000 m. Individual Ck values were evaluated in tests of 6, 5, and 2 min at average speeds of 84%, 90%, and 100% of the 1000-m race speed. RESULTS: The V˙O2max values determined during the incremental or the 2-min test were not significantly different (4613 ± 619 vs 4582 ± 598 mL·min). The Ck (J·kg·m) of male kayakers increased from approximately 4 (at 3.23 m·s) to approximately 6 (at 4.63 m·s) and was approximately 30.7% smaller than that of male canoeists (P<0.001). Over the same speed range, male kayakers were approximately 14.2% more economical than female kayakers (P=0.044). CONCLUSIONS: Individual theoretical best times and speeds were essentially equal to those measured during actual competitions.