Effect of caffeine on submaximal exercise performance at altitude

Area of Science:

• Sports Science
• Altitude Physiology
• Nutritional Supplementation

Background:

• High altitude exposure (HA) impairs exercise performance due to reduced oxygen availability.
• Caffeine (CAF) is a known ergogenic aid, but its effects at HA require further investigation.
• Understanding CAF's role in mitigating altitude-induced performance decrements is crucial for athletes.

Purpose of the Study:

• To investigate the effects of caffeine supplementation on exercise performance at sea level (SL) and high altitude (HA).
• To determine if caffeine enhances endurance exercise to exhaustion (ETX) during acute and chronic HA exposure.

Main Methods:

• Eight young males completed submaximal endurance tests to exhaustion (ETX) at SL, after 1 hour (acute) at 4,300m, and after 2 weeks (chronic) at 4,300m.
• Subjects received either caffeine (4 mg.kg-1) or a placebo 1 hour before each test in a double-blind crossover design.
• Exercise performance was measured as time to exhaustion (ETX) at ~80% of altitude-specific maximal aerobic power.

Main Results:

• Caffeine had minimal effect on ETX at SL (p=0.21).
• Caffeine significantly increased ETX by 54% during acute HA exposure (p=0.004).
• Caffeine tended to improve ETX by 24% during chronic HA exposure (p=0.084).

Conclusions:

• Caffeine supplementation can enhance endurance exercise performance at high altitude, particularly during acute exposure.
• The performance enhancement at HA may be linked to increased tidal volume or reduced impairment of muscular force production.
• Caffeine shows potential as an effective ergogenic aid for individuals exercising in hypoxic conditions.