Acceleration Tolerance After Ingestion of a Commercial Energy Drink

Walker TB, Balldin U, Fischer J, Storm W, Warren GL. Acceleration tolerance after ingestion of a commercial energy drink. Aviat Space Environ Med 2010; 81:1100–6.

Background: Caffeine ingestion has been demonstrated to increase physical performance in some situations. This study examined the ability of a commercial energy drink containing caffeine to enhance acceleration tolerance and strength under G load. Methods: Eight experienced centrifuge subjects completed three separate experimental acceleration exposures following ingestion of 11.5 ml · kg⁻¹ bodyweight of 1) a commercial energy drink, providing 5.0 mg caffeine/kg bodyweight; 2) a commercial energy drink without caffeine; or 3) a placebo. The acceleration exposures consisted of a relaxed gradual onset run to peripheral light loss, a rapid onset run to 6 G for 15 s, and a simulated air combat maneuver (SACM) run of repeated alternations between 4.5 G for 15 s and 7 G for 15 s until volitional exhaustion. Results: Relaxed G tolerance was 13% higher under the caffeinated energy drink session, whereas SACM duration did not differ among the drink conditions. Hip adductor muscle strength was 37% lower during the placebo session than during the other two sessions. Conclusion: Consumption of a caffeine-based energy drink may enhance relaxed G tolerance and may increase strength, but does not impact acceleration tolerance duration.