Blood lactate concentration/heart rate relationship: laboratory running test vs field roller skiing test

Laboratory treadmill running tests are commonly used to assess the effects of training programs and to prescribe training intensity for cross-country skiers. The present study compared the blood lactate concentration ([La])/heart rate (HR) relationship obtained during a laboratory treadmill running test and used to prescribe training intensities, to the same relationship obtained during a field roller skiing test in ten young male cross-country skiers of national level. The laboratory test consisted of a maximal incremental protocol involving 3 min steps during which metabolic and cardio-respiratory parameters were measured. The field test comprised four loops (4 km long) at different intensities from warm-up speed to maximum aerobic speed during which HR and [La] were measured. For a given HR, [La] values obtained during the field test were significantly higher compared with those measured in the laboratory test (mean difference from 0.2 mmol x l -1 for HR = 147 bpm, to 4.9 mmol x l -1 for HR = 182 bpm; p < 0.05). Exercise specificity, i. e. upper body involvement for roller skiing, as well as protocol characteristics, particularly longer step duration, could explain this discrepancy. The results of the present study highlight the importance of exercise and protocol specificity for [La]/HR relationship currently used to prescribe exercise intensity in cross-country skiing.