By Johan Trygg

Petter Northug often used the tactic of staying behind his opponents in order to be more alert at the end of the race. Now Swedish researchers have found out exactly how much energy you save on using Petter's tactics.

Mats Ainegren at the Sports Tech Research Center, Mid Sweden University, led the research where they studied the effects of drafting in cross-country skiing.

“It has been known for a long time that it can often be advantageous to stay behind in cross country skiing. But how beneficial and in what circumstances nobody has known. Through the figures we have produced, it becomes clearer to athletes and coaches how much importance you should put on this aspect during training and competition,” says Mats Ainegren to the Swedish sports research site, idrottsforskning.se.

In the experiments conducted on a large treadmill in a wind tunnel, it was tested how oxygen consumption (VO2) and heart rate were affected by lying first on the treadmill compared to lying behind another skier. A total of ten male and ten female elite athletes participated in the study. The effects of drafting were studied at different speeds and corresponding speed winds, and the athletes used classic double poling technique.

The results showed that when double poling at the speed of 5 m/s or faster, it was a significant difference in both oxygen consumption and heart rate to lay behind another rider, versus to lie first. For men, the difference in oxygen consumption was about 3-5 percent and for women about 2.5 percent. For women, it was then required that the speed was 6 m/s.

“What we are talking about here are the speeds that the elite have in flat terrains, for example in Vasaloppet. At the speed of recreational skiers, it plays a marginal role in whether you are in front or behind, it must move faster for the air resistance to have a sufficiently large impact. Unless it blows headwind of course. Then the difference becomes even more significant and the effects of "drafting" become interesting even at the recreational skier's speed, ” says Mats Ainegren.

But the question is how to really interpret the 3-5 percent difference in oxygen consumption. Is it much or little in this context? Mats Ainegren believes that this figure can be compared with the difference in energy consumption that exists between an elite athlete with a very good technique and an elite athlete with poorer technique.

Now it remains to be seen if anyone wants to lead the pack in the future. The study did not investigate the outcome of skiing in a long line where the unsteady movement of a large group of skiers can cause a so-called “yo-yo” effect where skiers need to stop on steep climbs and then start skiing again from zero speed, and thus end up spending a lot of unnecessary energy while racing.

You can read the full article in Swedish here: https://www.idrottsforskning.se/sa-mycket-energi-sparar-elitakaren-pa-att-kora-northug-taktiken/