Physiological demands of the Absa Cape Epic mountain bike race and predictors of performance

[摘要] ENGLISH ABSTRACT: The purpose of this qualitative-quantitative study was to describe the exercise intensity andpredictors of performance of a multi-stage mountain bike (MTB) race (2014 Absa Cape Epic)lasting 8 days. Twenty-three amateur mountain bikers (age 39 ± 9 years, height 178.8 ± 8.2cm, body mass 74.7 ± 9.1 kg, VO2max 54 ± 7 ml.kg-1.min-1) who completed the 2014 AbsaCape Epic were involved in the study. The participants were divided into two groupsaccording to their MTB experience. The experienced group included participants whopreviously completed more than three 3-day multi-stage MTB events and the novices groupincluded those who has completed less than 3-day multi-stage MTB events.Prior to the event the participants completed a maximal aerobic cycling test and a simulated40 km time trial (TT). The maximal aerobic test was used to determine 3 work intensityzones based on heart rate (HR) corresponding to blood lactate thresholds (LT: increase inblood lactate concentration of 1 mmol.l-1 above baseline values and the onset of bloodlactate accumulation (OBLA), a fixed blood lactate concentration of 4 mmol.l-1). There wereno statistically significant differences in the physical, physiological and performancevariables measured in the laboratory between the two groups.The exercise intensity during the Cape Epic was measured using telemetric HR monitoringsets. RPE values were noted after each stage of the race. The mean HR was 88.1 ± 5.3%(experienced) and 84.2 ± 11.0% (novices) of maximal HR during the race or 88.9 ± 3.5%(experienced) and 85.9 ± 10.6 (novices) of laboratory determined maximum HR. More timewas spent in the 'low HR zone (43.1 % vs 58.5 %, respectively), while only a small amountof time was spent in the 'hard HR zone (7.4% and 6.1%, respectively). The experiencedgroup spent statistically significantly more time in the 'moderate HR zone compared to thenovices group (49.5 % vs. 35.4 %). The experienced group performed significantly betterduring the event compared to the novices group in both the total event time (P = 0.004) andthe general classification (P = 0.01).Relative and absolute power output (PO) at OBLA (P = 0.01 and 0.02, respectively) werestatistically significant predictors of total event time, while relative peak power output was asignificant predictor of general classification for the event (P = 0.02) . The total TT time wasa significant predictor of average event HR (P = 0.03).This study showed that this MTB stage race is physiologically very demanding and requirescyclists to have excellent endurance capacity, as well as strength and power. Theparameters from the maximal aerobic capacity test correlated better with outdoorperformance than parameters from the simulated 40 km TT. Therefore the standardmaximal aerobic capacity test are sufficient for testing mountain bikers and sport scientistscan continue using this test to prescribe exercise intensity zones for training and events.

[发布机构] Stellenbosch University