Team sports – such as football, rugby, handball, hockey, or basketball – are characterized by alternating short efforts of very high intensity (<10 seconds) with recovery periods at a lower intensity. That is why the ability to sprint repeatedly will be key for the performance of these players.¹ In fact, various studies have observed that players who compete in a higher competitive category (for example, professionals rather than semi-professionals) perform better in repeated sprint tests.²

Therefore, training the ability to perform repeated sprints is one of the fundamental pillars in planning team sports. It has been shown that repeated sprint training increases athletes’ maximum oxygen consumption, peak speed and average speed when performing several consecutive sprints.³ In this sense, although repeated sprint sessions are typically carried out in normoxia (that is, with an average oxygen concentration), more and more evidence shows that performing such sessions in hypoxia (with a concentration of reduced expired oxygen, such as when training at high altitude or with an artificial hypoxia generator) could provide more significant benefits.

Confirming the potential of performing repeated sprints in hypoxia, a meta-analysis published in the prestigious journal Sports Medicine and carried out by experts in hypoxia, Franck Brocherie, and Grégoire Millet, analysed the published studies. These studies compared the effects of this type of training with the same training performed in normoxia.⁴ After including 9 studies with more than 200 total participants (including different sports such as football, lacrosse, hockey, rugby, or even cyclists and cross-country skiers), the results showed that sprint training in hypoxia (performed by cycling or running, and including an average of 2-3 weekly sessions for 4 weeks) improved average sprint performance to a greater extent than such training in normoxia. Even concise sprint interventions in hypoxia are beneficial. For example, one study compared the effects of just 4 sprint sessions (3 blocks of 8 10-second sprints, with 20 recovery seconds between sprints) performed in normoxia or hypoxia for two weeks by rugby players. The results showed that if these 4 sessions were conducted in hypoxia, the players improved their maximum and average capacity in the sprints to a greater extent.⁵

Interestingly, although most studies have evaluated the effects of performing repeated sprints with artificial hypoxia induced by a hypoxia generator – something that is not available to all teams – more and more evidence shows that benefits could arise even when producing such hypoxia through voluntary hypoventilation (that is, simply holding your breath during sprints). For example, one study evaluated rugby players who performed a 40-meter repeated sprint session with hypoventilation or normal breathing.⁶ After 4 weeks of training, they observed that those who had tried to hold their breath during sprints improved the number of efforts they could repeat until fatigue (from 9 to 15), while the control group did not improve their performance.⁶

The exact mechanism by which hypoxia sprint training maximises performance gains is still unknown compared to the same training in normoxia. However, it has been proposed that hypoxia could further stimulate fast fibre recruitment and glycolytic metabolism, thus contributing to improvements in muscle power.^7.8 In addition, training in hypoxia could improve the buffering capacity of the muscle (which would attenuate the fatigue induced by the accumulation of metabolites during sprints) and promote angiogenesis and mitochondrial biogenesis to a greater extent. In other words, the creation of new capillaries and mitochondria at the muscular level.^7.8 Therefore, the benefits of repeated sprints performed in hypoxia seem to be mainly due to adaptations at the peripheral level (at the muscular level) and not so much at the central level as occurs with other types of traditional training in hypoxia. For example, stays at altitude, which mainly improve the capacity to transport oxygen to the tissues thanks to an increase in erythropoiesis.

Conclusion

Improving the ability to sprint repeatedly should be a primary goal in most team sports. For this, specific training of this capacity by performing repeated sprint protocols seems to be one of the most effective strategies, and although benefits can be obtained by performing such training in normoxia (i.e., under normal oxygen conditions), its performance in hypoxia (using an artificial hypoxia generator, or even through voluntary hypoventilation in case of fewer resources) seems to maximize the benefits obtained.

References

1. Girard O, Mendez-Villanueva A, Bishop D. Repeated-sprint ability part I: Factors contributing to fatigue. Sport Med. 2011;41(8):673-694. doi:10.2165/11590550-000000000-00000
2. Aziz AR, Mukherjee S, Chia MYH, Teh KC. Validity of the running repeated sprint ability test among playing positions and level of competitiveness in trained soccer players. Int J Sports Med. 2008;29(10):833-838. doi:10.1055/s-2008-1038410
3. Bishop D, Girard O, Mendez-Villanueva A. Repeated-Sprint Ability – Part II Recommendations for Training. Sport med. 2011;41(9):741-756.
4. Brocherie F. Effects of Repeated-Sprint Training in Hypoxia on Sea-Level Performance : A Meta-Analysis. Sport Med. 2017;47:1651-1660. doi:10.1007/s40279-017-0685-3
5. Beard A, Ashby J, Chambers R, Brocherie F, Millet G. Repeated-Sprint Training in Hypoxia in International Rugby Union Players. Int J Sport Physiol Perform. 2019;14(6):850-854.
6. Fornasier-santos C, Millet GP, Woorons X. Repeated-sprint training in hypoxia induced by voluntary hypoventilation improves running repeated-sprint ability in rugby players. Eur J Sport Sci. 2018;0(0):1-9. doi:10.1080/17461391.2018.1431312
7. Faiss R, Girard O, Millet GP. Advancing hypoxic training in team sports : from intermittent hypoxic training to repeated sprint training in hypoxia. Br J Sports Med. 2013;47:45-50. doi:10.1136/bjsports-2013-092741
8. Girard O, Brocherie F, Millet GP. Effects of Altitude/Hypoxia on Single- and Multiple-Sprint Performance: A Comprehensive Review. Sport Med. 2017;47(10):1931-1949. doi:10.1007/s40279-017-0733-z