Fatigue in a simulated cross-country skiing sprint competition VILLE VESTERINEN 1,2 , JUSSI MIKKOLA 1 , ARI NUMMELA 1 , ESA HYNYNEN 1 ,& KEIJO HA ¨ KKINEN 2 1 KIHU Research Institute for Olympic Sport, Jyva ¨ skyla ¨, and 2 Department of Biology of Physical Activity, University of Jyva ¨ skyla ¨, Jyva ¨ skyla ¨ , Finland (Accepted 31 May 2009) Abstract The aim of this study was to assess fatigue during a simulated cross-country skiing sprint competition based on skating technique. Sixteen male skiers performed a 30-m maximal skiing speed test and four 850-m heats with roller skies on a tartan track, separated by 20 min recovery between heats. Physiological variables (heart rate, blood lactate concentration, oxygen consumption), skiing velocity, and electromyography (EMG) were recorded at the beginning of the heats and at the end of each 200-m lap during the heats. Maximal skiing velocity and EMG were measured in the speed test before the simulation. No differences were observed in skiing velocity, EMG or metabolic variables between the heats. The end (820–850 m) velocities and sum-iEMG of the triceps brachii and vastus lateralis in the four heats were significantly lower than the skiing velocity and sum-iEMG in the speed test. A significant correlation was observed between mean oxygen consumption and the change in skiing velocity over the four heats. Each single heat induced considerable neuromuscular fatigue, but recovery between the heats was long enough to prevent accumulation of fatigue. The results suggest that the skiers with a high aerobic power were less fatigued throughout the simulation. Keywords: Blood lactate concentration, muscle activity, oxygen consumption, skating technique, skiing velocity Introduction The nature of cross-country skiing has changed considerably in recent years. Several new competi- tion formats, such as mass start, pursuit, and sprint competitions, have been developed. Interval-type cross-country skiing sprint competitions differ from races over conventional distances (5–50 km) due to faster skiing velocities, and shorter and repeated performances. Official distances of sprint competi- tions are 800–1200 m for women and 1000–1400 m for men. Usually, sprint competitions require three heats to achieve a place in the finals. A cross-country skiing sprint competition begins with a qualification round, which is organized as an interval start. After the qualifications, the 30 fastest skiers compete in the quarter-finals. In each quarter-final, six skiers com- pete against each other and the two fastest skiers in each heat plus two ‘‘lucky losers’’ (the fastest skiers ranked third and fourth in each heat) qualify for the semi-finals. In the semi-finals, the two fastest skiers in each heat, plus two lucky losers, qualify for the A- final and the other six skiers for the B-final. As a result, the 12 best skiers compete in four heats, separated by periods of rest (about 10–30 min between the final heats). The physiological demands of sprint skiing differ from those of traditional cross-country skiing compe- titions. At the present time, there is limited informa- tion about the physiological responses and demands of cross-country skiing sprint competition. Sto ¨ ggl and colleagues (Sto ¨ ggl, Lindinger, & Mu ¨ ller, 2007) observed high oxygen consumption ( _ V O 2 ), blood lactate concentrations, and heart rates during three sprint heats in a simulated cross-country skiing sprint performed on a motor-driven treadmill. However, blood lactate concentration and _ V O 2 decreased over the heats, without changes in sprint performance. Zory and colleagues (Zory, Millet, Schena, Bortolan, & Rouard, 2006) observed an increase in blood lactate concentration and a decrease in the velocity of the final sprint over three 1200-m sprint skiing heats, indicating accumulation of fatigue. Maximal speed and blood lactate concentration were found to be strongly correlated with cross-country skiing sprint performance (Sto ¨ggl et al., 2007). However, maximal Correspondence: V. Vesterinen, KIHU Research Institute for Olympic Sport, Rautpohjankatu 6, FIN-40700 Jyva ¨skyla ¨, Finland. E-mail: ville.vesterinen@kihu.fi Journal of Sports Sciences, August 2009; 27(10): 1069–1077 ISSN 0264-0414 print/ISSN 1466-447X online Ó 2009 Taylor & Francis DOI: 10.1080/02640410903081860 Downloaded By: [Jyvaskylan Yliopisto] At: 06:46 24 August 2009