Hypohydration adversely affects lactate threshold in endurance athletes.

Area of Science:

• Exercise Physiology
• Sports Science
• Human Performance

Background:

• Dehydration is common in athletes and can impact physiological responses during exercise.
• Understanding the effects of hypohydration on metabolic markers is crucial for performance optimization.
• Lactate threshold (LAT) is a key indicator of endurance capacity.

Purpose of the Study:

• To investigate the impact of hypohydration (-4% body mass) on the lactate threshold (LAT) in collegiate athletes.
• To determine if dehydration alters cardiovascular function or buffering capacity during exercise.

Main Methods:

• 14 collegiate athletes (8 men, 6 women) underwent randomized treadmill tests in euhydrated and hypohydrated states.
• Hypohydration was induced by exercise in a thermoneutral environment, resulting in ~3.9% body mass loss.
• Measurements included blood lactate, V(O)2, minute ventilation (VE), heart rate (HR), and rating of perceived exertion (RPE).

Main Results:

• Lactate threshold (LAT) occurred at a significantly lower absolute V(O)2, VE, R value, and RPE in the hypohydrated condition.
• Blood lactate concentration at peak exercise was significantly lower in hypohydration (6.7 mmol) versus euhydration (10.2 mmol).
• No significant differences were observed in heart rate or bicarbonate buffering capacity between hydration states.

Conclusions:

• Hypohydration causes the lactate threshold (LAT) to occur at a lower absolute exercise intensity in collegiate athletes.
• Dehydration appears to not significantly alter cardiovascular function or buffering capacity.
• Reduced exercise intensity at LAT suggests impaired aerobic metabolism or increased reliance on anaerobic glycolysis during hypohydration.