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Purpose Repeated-sprint training in hypoxia (RSH) was recently shown to improve repeated-sprint ability (RSA) in cycling. This phenomenon is likely to reflect fiber type-dependent, compensatory vasodilation, and therefore, our hypothesis was that RSH is even more beneficial for activities involving upper body muscles, such as double poling during cross-country skiing. Methods In a double-blinded fashion, 17 competitive cross-country skiers performed six sessions of repeated sprints (each consisting of four sets of five 10-s sprints, with 20-s intervals of recovery) either in normoxia (RSN, 300 m; FiO2, 20.9%; n = 8) or normobaric hypoxia (RSH, 3000 m; FiO2, 13.8 %; n = 9). Before (pre) and after (post) training, performance was evaluated with an RSA test (10-s all-out sprints20-s recovery, until peak power output declined by 30%) and a simulated team sprint (team sprint, 3 x 3-min all-out with 3-min rest) on a double-poling ergometer. Triceps brachii oxygenation was measured by near-infrared spectroscopy. Results From pretraining to posttraining, peak power output in the RSA was increased (P < 0.01) to the same extent (29% 13% vs 26% +/- 18%, nonsignificant) in RSH and in RSN whereas the number of sprints performed was enhanced in RSH (10.9 +/- 5.2 vs 17.1 +/- 6.8, P < 0.01) but not in RSN (11.6 +/- 5.3 vs 11.7 +/- 4.3, nonsignificant). In addition, the amplitude in total hemoglobin variations during sprints throughout RSA rose more in RSH (P < 0.01). Similarly, the average power output during all team sprints improved by 11% +/- 9% in RSH and 15% +/- 7% in RSN. Conclusions Our findings reveal greater improvement in the performance of repeated double-poling sprints, together with larger variations in the perfusion of upper body muscles in RSH compared with those in RSN.
Davide Ferri, Oliver Kröcher, Maarten Nachtegaal, Rob Jeremiah G. Nuguid
Berend Smit, Luc Patiny, Kevin Maik Jablonka