In the past, it has been challenging for researchers to track biometric changes throughout endurance events. While heart rate monitors have become easy to wear, evaluating sleep often requires extensive wiring and equipment, an impractical and cumbersome undertaking during multi-day, multi-location endurance events.
In a first-of-its-kind study,Central Queensland University (CQU) and WHOOP partnered together to prove the feasibility and accuracy of wearables for professional cycling tours and improve our understanding of how sleep and cardiovascular function change during these types of events. Riders across two women’s teams and one men’s team wore WHOOP for the duration of the Tour de France and Tour de France Femmes, and WHOOP data was analyzed to evaluate sleep duration, sleep staging, strain, heart rate, and heart rate variability.
By tracking these metrics continuously, researchers can investigate the true impact of a grand tour on the body – and findings can be used to improve athlete preparation and recovery.
The Tour de France is a 21-stage cycling race held in July. The tour covers mountainous terrain, winding city streets, and hilly countryside with stages frequently over 5 hours in duration. Over the course of three weeks, athletes in the 2022 Tour de France raced over 2,000 miles, with the longest stage over 135 miles.
The Tour de France Femmes returned in 2022 for the first time in its current format. It is shorter than the Tour de France but equally challenging with just 8 stages that cover 642 miles.
Professional cyclists often have high heart rate variability (HRV) and low resting heart rates due to the extreme cardiovascular load of endurance cycling. Both at the baseline level and throughout the tours, athletes wearing WHOOP averaged an hour longer of sleep every night compared to the general population.
To see just how hard athletes work on these stages, we examined what the strain of the average WHOOP member aged 20-29 looks like when carrying out a similar cycling ride. Stage 5 of the women’s 2022 tour and Stage 3 of the men’s 2022 tour were about 110 miles in length and relatively flat, with both groups of riders completing the stages between 4.5 and 5 hours. The women cyclists averaged a strain of 19.7, while the male cyclists averaged an 18.3 strain. For WHOOP members, a similar distanced ride averages a 17.4 strain, but takes an average of 6.5 hours to complete.
Throughout the tour as fatigue sets in, it is expected that resting heart rate would increase and heart rate variability would decrease. However, in this study, there was very little change in both HRV and RHR throughout the race for both groups of cyclists. This may be a result of extensive endurance training that allows them to moderate the impacts on their body.
Another goal of this study was to investigate how different stages may impact riders differently. While each rider may have their own specialty (climbing vs. speed) and thus fatigue differently, we can still look at the impact that stage types have on the team as a whole.
In the tour there are four main types of stages:
This study found that for male athletes, the type of stage classification had an impact on the rider’s next-day heart rate variability, with HRV 23.9ms lower on the days following mountain stages than rest days. Lower HRV is often an indication that your body is working hard. There was no significant impact on female cyclists’ heart rate variability during their tour by stage type. However, they did experience a higher percentage of light sleep (+11.4%), suggesting that sleep obtained after the mountain stages was less restful.
Additionally, day strain was the lowest for Individual Time Trials and then Flat stages, with average strain increasing as the stages became hilly and then mountainous.
Thanks to this latest study, wearables are making it possible to study the unique physiological circumstances that take place during endurance events, and help athletes and coaches understand how to best optimize training as a result.
