Heart rate, blood lactate concentration and estimated energy expenditure in a semi-professional rugby league team during a match: a case study

The aim of this study was to examine heart rate, blood lactate concentration and estimated energy expenditure during a competitive rugby league match. Seventeen well-trained rugby league players (age, 23.9±4.1 years; V·iO2max, 57.9±3.6 ml·kg1·min-1; height, 1.82±0.06 m; body mass, 90.2±9.6 kg; mean±s) participated in the study. Heart rate was recorded continuously throughout the match using Polar Vantage NV recordable heart rate monitors. Blood lactate samples (n=102) were taken before the match, after the warm-up, at random stoppages in play, at half time and immediately after the match. Estimated energy expenditure during the match was calculated from the heart rate-V·iO2 relationship determined in laboratory tests. The mean team heart rate (n=15) was not significantly different between halves (167±9 vs 165±11 beats·min-1). Mean match intensity was 81.1±5.8% V·iO2max. Mean match blood lactate concentration was 7.2±2.5 mmol·l-1, with concentrations for the first half (8.4±1.8 mmol·l-1) being significantly higher than those for the second half (5.9±2.5 mmol·l-1) (P<0.05). Energy expenditure was approximately 7.9 MJ. These results demonstrate that semi-professional rugby league is a highly aerobic game with a considerable anaerobic component requiring high lactate tolerance. Training programmes should reflect these demands placed on players during competitive match-play.