No relationship exists between urinary NT-proBNP and GPS technology in professional rugby union

Objectives We investigated the level of cardiovascular stress associated with professional rugby union and whether these changes could be explained through external workload systems like GPS and video analysis. Design Urine samples (14 in game one and 13 in game two) were collected from professional rugby players before, immediately post- and 36 h post-play in two consecutive games. Methods Urine was analysed for NT-proBNP by ELISA. Comparison with GPS (player-load and distance covered at specific speed bands) and video analysis (total impacts) were conducted. Results There was a significant increase in urinary NT-proBNP during game one (31.6 ± 5.4 to 53.5 ± 10.8 pg/mL) and game two (35.4 ± 3.9 to 49.8 ± 11.7 pg/mL) that did not correlate with the number of impacts, total distance covered, distance covered at pre-determined speed bands or player-load. Concentrations returned to pre-game concentrations 36 h post-game whilst a large inter-individual variation in NT-proBNP was observed among players (p < 0.001). Conclusions Professional rugby union causes a transient increase in cardiovascular stress that seems to be independent of the external workload characteristics of a player.