Do women enjoy better muscle recovery?

January 2019: Jasmin Paris, a 35-year old British runner, became the first woman to win the Montane Spine Race, a 430 kilometre ultramarathon covering the entire length of the Pennine Way, in the UK. Achieving a time of 83 hours and 12 minutes, she smashed the previous record set in 2016 by Eoin Keith, who took twelve hours longer. (This image from 2016 shows her participation in the Jura Fell Race on one of the Scottish islands).

Caroline Nicol, who is a physiologist, had already noted that for years now, seemingly tireless women have featured in the performance rankings of very long races such as the Diagonale des Fous (Grand Raid) on Reunion Island or the Mont-Blanc Ultra-Trail. However, of the hundreds of scientific publications on functional recovery (the time required to recover the ability to repeat an effort), only seven dealt with women. For her next study, she therefore decided to compare the two genders.

The study was performed on several editions of the Marseille-Cassis race, which has drawn crowds for forty years and attracts 20,000 runners, a third of them women. Its 20 kilometres of effort through the Calanques National Park offer a breathtaking landscape but are very hard on the legs, as the gradients are sometimes incredibly steep.

Each impact on the ground represents twice or three times the body’s weight. Their repetition generates muscle fatigue and stiffness that can last for several days. However, the disappearance of these effects does not necessarily correspond to full recovery.

To record the muscle activity associated with functional recovery, electrodes were placed on certain participants who agreed to carry out different exercises. These were mainly jumps, which were performed before the race, the following day (at peak stiffness) and a few days after that.

Here, a volunteer is performing drop jumps; she drops down on her feet before jumping up as fast and as high as possible. As a result, functional deficits persisted for four days after the race among men, while women had recovered as early as the second day.

The Marseille-Cassis race is particular in that the second part is all downhill. This harsh gradient places much more strain on the hamstrings – muscles up the back of the thighs which are deemed to be weaker in women – than a race on the flat or the drop jumps referred to above, which call more upon the triceps surae in the calves.

This participant was asked to sit on a seat weighing 15 kg and sliding along an inclined plane. Released at a given height, she was required to resist crushing on impact, a little like in a downhill race, and then to rebound as fast and as high as possible. The result was that only this test, which involves the hamstrings in particular, displayed incomplete functional recovery among women on the fourth day, in the same way as the men.

To monitor structural recovery as well (regeneration of the muscle fibre structure), volunteers underwent an MRI (magnetic resonance imaging) at a biological and medical magnetic resonance imaging unit on the days they performed the jump tests.

Muscle micro-lesions, or rather markers of muscle inflammation and swelling, could thus be localised and their course followed during the days of recovery. Initial analyses did not demonstrate any difference between men and women, except at the level of the hamstring muscles, which displayed more inflammation in women.

Finally, women recover earlier at the functional level, except in tests that involve the hamstring muscles. If these results are confirmed, athletes will perhaps benefit from specific training in the future, for both uphill and downhill running, in order to strengthen these particular muscles… and possibly break further records.