Risk of REDs for endurance athletes

· Risk of REDs for endurance athletes ·

Hi Saturday Morning Fan,

Correction: In last week’s newsletter, I wrote that creatine should be supplemented at a daily dose of 0.3g/kg. This is incorrect and far too high. The correct dose is 3-5g per day. If you acted on the previous recommendation, please adjust your intake to the correct dose.

This week, I am sharing an interesting study involving athletes preparing for the Winter Olympics. The study examined the prevalence of RED-S (Relative Energy Deficiency in Sport) in elite winter sport athletes. Several findings are relevant and useful for endurance athletes at all levels.

What did the study find?

The researchers assessed 101 elite winter sport athletes for RED-S risk using a validated clinical assessment tool. They also used two different imaging techniques to evaluate bone density.

17% of the athletes were classified as being at risk of RED-S. Most of these athletes were female and competed in endurance-based disciplines. Athletes in the at-risk group were approximately twice as likely to show lower total volumetric bone mineral density and reduced failure load at the tibia.

How does this compare to previous research?

A similar earlier study assessed 213 elite athletes for RED-S risk and bone mineral density. That study reported a much higher overall prevalence of RED-S risk.

55% of athletes were classified as green, 36% as yellow, 5% as orange, and 4% as red. Higher RED-S severity was associated with increased bone stress injury risk, particularly in athletes with amenorrhea, low sex drive, or elevated eating disorder scores.

In the newer winter sport study, the authors suggested that the lower prevalence of RED-S risk may be partly explained by the support provided by the Canadian Sport Institute, including access to sports dietitians.

What does this mean for us?

Although elite athletes train at very high volumes, the consistently high prevalence of RED-S risk remains concerning. The associated health and performance consequences reinforce the need for caution when restricting calories in endurance athletes. In most cases, energy restriction should not be undertaken without expert guidance.

Fueling during training is important, and this is where Saturday can help. However, total daily energy intake matters just as much. Athletes should be conservative and ensure they are adequately fueling for both training demands and daily life. Better fueling supports better training, which ultimately leads to better performance.

References

Smith, Emily M et al. “New approach to identifying elite winter sport athletes’ risk of relative energy deficiency in sport (RED-S).” BMJ Open Sport & Exercise Medicine, vol.11, no.1, e002320, 30 Jan. 2025.

Heikura, Ida A et al. “Application of the IOC Relative Energy Deficiency in Sport (RED-S) Clinical Assessment Tool version 2 (CAT2) across 200+ elite athletes.” British Journal of Sports Medicine, vol.59, no.1, pp.24-35, 23 Dec. 2024.

Have any thoughts, comments, or questions that you'd like to share? Please email us anytime!

Daniel

Endurance Athlete, Coach, and Saturday Customer Support.