Endurance performance and physiology: training the aerobic engine

Updated IOC consensus on Relative Energy Deficiency in Sport (formerly RED-S), including the REDs CAT2 assessment tool.

• Reframes low energy availability as the root cause of a syndrome affecting many body systems, not only bone and menstrual health, in male and female athletes.
• Introduces the REDs Clinical Assessment Tool version 2 (IOC REDs CAT2) to stratify athletes by risk and guide return-to-training decisions.
• Recommends a multidisciplinary approach to prevention, screening and management rather than reliance on any single biomarker.

Our appraisal: An expert consensus (large author panel with structured review) that sets the current framework for assessing energy availability; it standardises language and screening rather than proving that any specific intervention restores health or performance. Treat the CAT2 risk categories as a structured clinical aid, not a validated diagnostic test.

Global guidelines on physical activity and sedentary behaviour across the lifespan and clinical populations.

• Adults should do 150 to 300 minutes of moderate, or 75 to 150 minutes of vigorous, aerobic activity per week, plus muscle strengthening on two or more days.
• Some physical activity is better than none, and any amount counts toward health benefits; sedentary time should be limited.
• Recommendations extend across the lifespan and to pregnancy, older adults and people with chronic conditions or disability.

Our appraisal: A GRADE-informed guideline from a large evidence review, so the dose targets are among the better-grounded numbers in this field. Its limitation is deliberate breadth: it sets population activity doses, not sport-specific training prescriptions, and stops short of a firm sedentary-time threshold.