Gym performance depends on more than protein and sleep. A review in Research Quarterly for Exercise and Sport looked at how dehydration affects anaerobic performance, the short, hard efforts that resemble lifting and sprinting.
What the review found
The 2012 review concluded that the level of body-water deficit that affects anaerobic performance (about 3 to 4%, depending on the exercise mode) is larger than the deficit that impairs endurance performance (about 2%). Moderate dehydration of about 3% of body weight impaired repeated anaerobic bouts, which place a greater demand on the aerobic system. The authors noted that performance duration, dehydration mode and the work-to-recovery ratio all influence the threshold.
What this means for lifters
- A single hard set is less sensitive to small fluid losses than endurance work, but repeated efforts suffer when you are clearly dehydrated.
- Start sessions well hydrated and sip water through longer sessions.
- Very hot environments, heavy sweating and long sessions call for more attention to fluid.
- Drink to thirst and check urine colour as a rough guide.
For fuelling during training see our workout nutrition guide.
Frequently asked questions
How much dehydration affects strength training?
The 2012 review found moderate dehydration of about 3% of body weight impaired repeated anaerobic bouts.
Is anaerobic performance more or less sensitive than endurance?
The review found the threshold for anaerobic performance (about 3 to 4%) is larger than for endurance (about 2%).
How can I tell if I am dehydrated?
Thirst, dark urine and clearly reduced performance are common signs. Medical advice applies if you have a health condition.
References
- Kraft JA, Green JM, Bishop PA et al. (2012). The influence of hydration on anaerobic performance: a review. Res Q Exerc Sport. PubMed 22808714
General information, not medical advice. Check with a doctor before starting a new training or supplement routine. Last updated 27 October 2026.
