title: Combining internal- and external-training-load measures in professional rugby league.
abstract: OBJECTIVE
  This study investigated the effect of training mode on the relationships between measures of training load in professional rugby league players.
  
  
  METHODS
  Five measures of training load (internal: individualized training impulse, session rating of perceived exertion; external-body load, high-speed distance, total impacts) were collected from 17 professional male rugby league players over the course of two 12-wk preseason periods. Training was categorized by mode (small-sided games, conditioning, skills, speed, strongman, and wrestle) and subsequently subjected to a principal-component analysis. Extraction criteria were set at an eigenvalue of greater than 1. Modes that extracted more than 1 principal component were subjected to a varimax rotation.
  
  
  RESULTS
  Small-sided games and conditioning extracted 1 principal component, explaining 68% and 52% of the variance, respectively. Skills, wrestle, strongman, and speed extracted 2 principal components each explaining 68%, 71%, 72%, and 67% of the variance, respectively.
  
  
  CONCLUSIONS
  In certain training modes the inclusion of both internal and external training-load measures explained a greater proportion of the variance than any 1 individual measure. This would suggest that in training modes where 2 principal components were identified, the use of only a single internal or external training-load measure could potentially lead to an underestimation of the training dose. Consequently, a combination of internal- and external-load measures is required during certain training modes.
authors.affiliation: Dept of Sport, Health and Exercise Science, University of Hull, Kingston upon Hull, UK.
authors.forename: Dan
authors.initials: D
authors.lastname: Weaving
authors.forename: Phil
authors.initials: P
authors.lastname: Marshall
authors.forename: Keith
authors.initials: K
authors.lastname: Earle
authors.forename: Alan
authors.initials: A
authors.lastname: Nevill
authors.forename: Grant
authors.initials: G
authors.lastname: Abt
mesh_terms: D061725:Accelerometry / Q000379:methods; D000328:Adult; D005538:Football / Q000502:physiology* / Q000523:psychology; D040362:Geographic Information Systems; D006339:Heart Rate; D006801:Humans; D008297:Male; D010465:Perception; D010806:Physical Education and Training / Q000379:methods*; D005082:Physical Exertion; D025341:Principal Component Analysis; D055815:Young Adult