title: A comparison of methods to quantify the in-season training load of professional soccer players.
abstract: OBJECTIVE
  To compare various measures of training load (TL) derived from physiological (heart rate [HR]), perceptual (rating of perceived exertion [RPE]), and physical (global positioning system [GPS] and accelerometer) data during in-season field-based training for professional soccer.
  
  
  METHODS
  Fifteen professional male soccer players (age 24.9 ± 5.4 y, body mass 77.6 ± 7.5 kg, height 181.1 ± 6.9 cm) were assessed in-season across 97 individual training sessions. Measures of external TL (total distance [TD], the volume of low-speed activity [LSA; <14.4 km/h], high-speed running [HSR; >14.4 km/h], very high-speed running [VHSR; >19.8 km/h], and player load), HR and session-RPE (sRPE) scores were recorded. Internal TL scores (HR-based and sRPE-based) were calculated, and their relationships with measures of external TL were quantified using Pearson product-moment correlations.
  
  
  RESULTS
  Physical measures of TD, LSA volume, and player load provided large, significant (r = .71-.84; P < .01) correlations with the HR-based and sRPE-based methods. Volume of HSR and VHSR provided moderate to large, significant (r = .40-.67; P < .01) correlations with measures of internal TL.
  
  
  CONCLUSIONS
  While the volume of HSR and VHSR provided significant relationships with internal TL, physical-performance measures of TD, LSA volume, and player load appear to be more acceptable indicators of external TL, due to the greater magnitude of their correlations with measures of internal TL.
authors: Exercise and Sport Science, University of Newcastle, Ourimbah, NSW, Australia.
authors: Brendan R
authors: BR
authors: Scott
authors: Robert G
authors: RG
authors: Lockie
authors: Timothy J
authors: TJ
authors: Knight
authors: Andrew C
authors: AC
authors: Clark
authors: Xanne A K
authors: XA
authors: Janse de Jonge
mesh_terms: D000054:Acceleration; D001315:Australia; D006801:Humans; D008297:Male; D010806:Physical Education and Training; D005082:Physical Exertion / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology; D012916:Soccer / Q000502:physiology*; D055815:Young Adult