title: Monitoring training in elite soccer players: systematic bias between running speed and metabolic power data.
abstract: We compared measurements of high-intensity activity during field-based training sessions in elite soccer players of different playing positions. Agreement was appraised between measurements of running speed alone and predicted metabolic power derived from a combination of running speed and acceleration. Data was collected during a 10-week phase of the competitive season from 26 English Premier League outfield players using global positioning system technology. High-intensity activity was estimated using the total distance covered at speeds >14.4 km · h⁻¹ (TS) and the equivalent metabolic power threshold of >20 W · kg⁻¹ (TP), respectively. We selected 0.2 as the -minimally important standardised difference between methods. Mean training session TS was 478±300 m vs. 727±338 m for TP (p<0.001). This difference was greater for central defenders (~ 85%) vs. wide defenders and attackers (~ 60%) (p<0.05). The difference between methods also decreased as the proportion of high-intensity distance within a training session increased (R2=0.43; p<0.001). We conclude that the high-intensity demands of soccer training are underestimated by traditional measurements of running speed alone, especially in training sessions or playing positions associated with less high-intensity activity. Estimations of metabolic power better inform the coach as to the true demands of a training session.
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom.
authors.forename: P
authors.initials: P
authors.lastname: Gaudino
authors.forename: F M
authors.initials: FM
authors.lastname: Iaia
authors.forename: G
authors.initials: G
authors.lastname: Alberti
authors.forename: A J
authors.initials: AJ
authors.lastname: Strudwick
authors.forename: G
authors.initials: G
authors.lastname: Atkinson
authors.forename: W
authors.initials: W
authors.lastname: Gregson
mesh_terms: D000054:Acceleration; D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D004739:England; D040362:Geographic Information Systems; D006801:Humans; D012420:Running / Q000502:physiology*; D012916:Soccer / Q000502:physiology*; D055815:Young Adult