The use of heart rates and graded maximal test values to determine rugby union game intensities
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In order for sport scientists and conditioning coaches to construct sport and position specific training regimens for players, they need to understand the physiological demands different playing positions face during rugby union matches. Despite the inaccuracy of timemotion, heart rate and blood lactate analyses, no researchers have to date attempted to determine the demands of tertiary institution rugby union games by using heart rate and graded maximal test values. It is against this background, that the purposes of this study were firstly, to determine the intensities of tertiary institution rugby union games, using heart rates and graded maximal test values, and secondly, to determine the positional differences in tertiary institution rugby game intensities, using heart rates and graded maximal test values. In the weeks between three rugby matches, ten forwards and eleven backs, who were selected from the first and second teams of the North–West University (Potchefstroom Campus, South Africa) performed a standard incremental maximal oxygen uptake ( 2max VO ? ) test to the point of exhaustion. The test was used to determine two ventilatory threshold points by means of which the low, moderate and high–intensity heart rate zones were identified for each of the players. These heart rate zones were used to determine the amount of time that each player spent in the different intensity zones during matches, whilst heart rate telemetry data was used. Significant differences (p < 0.05) were found between the amount of time each player spent in the low and high–intensity zones (23.2% vs. 37.4%) during the second halves, between the low and moderate (22.8% vs. 33.6%) as well as between the low and high–intensity zones (22.8% vs. 43.6%) for the matches overall. When the independent t–test values were calculated, the study revealed that forwards spent significantly more time in the highintensity zone compared to the backs (54.6% vs. 32.7%), whereas the backs spent significantly more time in the low–intensity zone during the match compared to the forwards (34.2% vs. 11.3%). Results also indicated that the duration of different intensity bouts were 29 sec for the low, 29 sec for the moderate and 1 min:17 sec for the high–intensity bouts, respectively. The results of this study showed that the combined use of heart rate and graded maximal test values enabled the researcher to determine the intensities of tertiary institution rugby union games as well as to investigate the significant differences between the game intensities of backs and forwards. The conclusion that can therefore be drawn from the results of this study are that in–game and graded maximal test heart rates as well as other respiratory–related variables will enable sport scientists and other sport–related professionals to draw more valid and accurate conclusions with regard to the demands of rugby union play. It also showed that players, and especially forwards, spent significantly more time in the high–intensity zone than was previously reported.
- ETD@PUK