Combining Internal- and External-Training-Load Measures in Professional Rugby League

Weaving, D.; Marshall, P.; Earle, K.; Nevill, A.; Abt, G.

Objective: The aim of this study was to investigate the effect of training mode on the relationships between measures of training load in professional rugby league players.

Methods: Training load data, including internal measures such as individualized training impulse and session rating of perceived exertion, as well as external measures like body load, high-speed distance, and total impacts, were collected from 17 professional male rugby league players over two 12-week preseason periods. Training sessions were categorized into different modes, including small-sided games, conditioning, skills, speed, strongman, and wrestle. A principal-component analysis was conducted to analyze the relationships between training load measures within each training mode. Modes that extracted more than one principal component underwent varimax rotation for further analysis.

Results: Small-sided games and conditioning extracted one principal component each, explaining 68% and 52% of the variance, respectively. Skills, wrestle, strongman, and speed training modes extracted two principal components, explaining 68%, 71%, 72%, and 67% of the variance, respectively.

Conclusions: The study found that in certain training modes where multiple principal components were identified, including both internal and external training load measures explained a greater proportion of the variance compared to using individual measures alone. This suggests that relying solely on a single internal or external training load measure in these modes could lead to an underestimation of the training dose. Therefore, a combination of internal and external load measures is necessary for accurate monitoring and assessment of training load in professional rugby league players during certain training modes.

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