When it comes to endurance sports like running, cycling, or triathlon, hydration can make or break performance. As an osteopath and sports dietitian, we often see how dehydration doesn’t just affect energy levels, it impacts muscle function, recovery, and overall movement quality.
Understanding hydration is key to keeping the body performing well and recovering efficiently.
Why Hydration Matters
Hydration underpins performance, recovery, and injury prevention. Water is involved in almost every physiological process and makes up around 75% of muscle tissue, allowing nutrients and oxygen to be delivered efficiently, metabolic waste to be removed, and muscles to contract and relax smoothly. During prolonged or endurance exercise, athletes may lose 1–2 litres of fluid per hour through sweat – often more in hot or humid conditions (Armstrong, 2021).
As fluid losses accumulate, blood volume falls, reducing the delivery of oxygen and nutrients to working muscles while increasing cardiovascular strain. Even a loss of approximately 2% of body weight through dehydration has been shown to impair endurance performance. This includes earlier onset of fatigue, reduced coordination, and measurable declines in cognitive function such as concentration, reaction time, and mood, with effects amplified in the heat.
From an osteopathic perspective, dehydration may present as increased muscle tension, fascial restriction, and reduced joint mobility, all of which affect performance and increase injury risk.
1. Hydration and Muscle Function
Dehydration alters the way muscles contract and recover. Studies show that maintaining hydration supports muscle contractility and delays fatigue during prolonged exercise (Königstein et al., 2022). When hydration is low, muscles are more likely to cramp or spasm, and connective tissues can become less pliable, leading to mechanical strain and compensatory movement patterns.
For osteopaths, addressing these muscular and fascial changes through manual therapy and movement re-education helps restore balance but hydration remains the foundation for healthy tissue function.
2. The Impact on Performance
Even mild dehydration, as little as 2% of body weight, can significantly reduce endurance capacity and concentration (Deshayes et al., 2022). It increases cardiovascular strain and core temperature, forcing the body to work harder to stay cool. A recent study also found that hydration directly affects perceived exertion and power output in endurance cycling under heat stress (Li et al., 2024).
Staying hydrated helps maintain energy, focus, and rhythm, all essential for consistent performance and preventing fatigue-related injury.
3. Where Dietitian Input is Needed
Osteopaths play an important role in educating athletes around general hydration principles, body awareness, and early physical signs of dehydration. However, developing specific fluid and electrolyte strategies sits within the scope of a sports dietitian. Dietitians are trained to assess individual sweat rates and electrolyte losses and to translate these findings into tailored hydration plans for both training and competition (Treff et al., 2024).
Persistent issues such as recurrent muscle cramps, early fatigue, or heat-related symptoms are strong indicators that a more targeted approach is required. In these cases, referral to a dietitian supports the development of an evidence-based hydration and nutrition plan that aligns with the athlete’s training load, environment, and performance goals.
A simple starting point is to estimate sweat losses by tracking body weight before and after a training session. Weigh yourself immediately before exercise and again after the session, ideally wearing minimal or no clothing. Subtract your post-exercise weight from your pre-exercise weight, divide this number by your starting weight, and multiply by 100 to determine percentage body weight loss.
Example:
An athlete completes a one-hour run.
Starting weight: 70 kg
Post-run weight: 68.5 kg
70 − 68.5 = 1.5 kg lost
1.5 ÷ 70 = 0.0214
0.0214 × 100 = 2.14% body weight loss
A loss greater than ~2% indicates dehydration at a level likely to impair performance and is a strong signal that an individualised hydration plan would be beneficial.
Practical Tips
- Start early: Don’t wait until you feel thirsty – hydrate before, during, and after training.
- Monitor colour: Pale yellow urine usually indicates adequate hydration.
- Include electrolytes: Especially for long sessions in hot conditions – consult your dietitian.
- Recover smart: Rehydration supports muscle repair and flexibility post-event.
Summary
Hydration is a fundamental pillar of endurance performance and recovery. From an osteopathic perspective, understanding how inadequate fluid intake influences muscle tone, joint mobility, and overall biomechanics allows practitioners to address the body as an integrated system. When this approach is paired with individualised hydration and electrolyte guidance from a sports dietitian, athletes are better supported to move efficiently, recover more effectively, and perform at their best – regardless of the distance or demands of their event.
Dr. Emily Sandman
Osteopath & Group Exercise Rehab Instructor
E: emily.Sandman@staytuned.com.au
Mel Emanuel
Sports Dietitian
E: melissa.emanuel@staytuned.com.au
References
- Armstrong, L. E. (2021). Rehydration during endurance exercise: Challenges, research, options, methods. Nutrients, 13(3), 887.
- Königstein, K., Niess, A. M., Carlsohn, A., & Treff, G. (2022). Hydration management in sports: A scoping review of prolonged and ultra-endurance exercise. German Journal of Sports Medicine.
- Deshayes, T., Pancrate, T., & Goulet, E. D. B. (2022). Impact of dehydration on perceived exertion during endurance exercise: A systematic review with meta-analysis. Journal of Exercise Science & Fitness.
- Li, X., et al. (2024). Effects of dehydration on cycling performance under heat stress. Physiology & Behavior, 273, 114053.
- Treff, G., et al. (2024). Towards precision sports nutrition for endurance athletes: A scoping review. Nutrients, 16(22), 3943.