title: Monitoring Locomotor Load in Soccer: Is Metabolic Power, Powerful?
abstract: The aim of the present study was to examine the validity and reliability of metabolic power (P) estimated from locomotor demands during soccer-specific drills. 14 highly-trained soccer players performed a soccer-specific circuit with the ball (3×1-min bouts, interspersed with 30-s passive recovery) on 2 different occasions. Locomotor activity was monitored with 4-Hz GPSs, while oxygen update (VO2) was collected with a portable gas analyzer. P was calculated using either net VO2 responses and traditional calorimetry principles (PVO2, W.kg(-1)) or locomotor demands (PGPS, W.kg(-1)). Distance covered into different speed, acceleration and P zones was recorded. While PGPS was 29±10% lower than PVO2 (d<- 3) during the exercise bouts, it was 85±7% lower (d<- 8) during recovery phases. The typical error between PGPS vs. PVO2 was moderate: 19.8%, 90% confidence limits: (18.4;21.6). The correlation between both estimates of P was small: 0.24 (0.14;0.33). Very large day-to-day variations were observed for acceleration, deceleration and > 20 W.kg(-1) distances (all CVs > 50%), while average Po2 and PGPS showed CVs < 10%. ICC ranged from very low- (acceleration and > 20 W.kg(-1) distances) to-very high (PVO2). PGPS largely underestimates the energy demands of soccer-specific drills, especially during the recovery phases. The poor reliability of PGPS >20 W.kg(-1) questions its value for monitoring purposes in soccer.
authors.affiliation: Paris Saint Germain FC, Performance, Saint-Germain-en-Laye, France.
authors.forename: M
authors.initials: M
authors.lastname: Buchheit
authors.affiliation: Olympic de Marseille Fooball Club, Physical Performance, Marseille, France.
authors.forename: C
authors.initials: C
authors.lastname: Manouvrier
authors.affiliation: Laboratory of Sport Sciences, Université de Franche-Comté, UFR STAPS Besançon, Besançon, France.
authors.forename: J
authors.initials: J
authors.lastname: Cassirame
authors.affiliation: Faculty of Sport Sciences, Université de Nice Sophia Antipolis, NICE, France.
authors.forename: J-B
authors.initials: JB
authors.lastname: Morin
mesh_terms: D000054:Acceleration; D004734:Energy Metabolism; D040362:Geographic Information Systems; D006801:Humans; D010101:Oxygen Consumption; D015203:Reproducibility of Results; D012420:Running / Q000502:physiology*; D012916:Soccer / Q000502:physiology*; D013996:Time and Motion Studies