Effect of caffeine supplementation on exercise performance, power, markers of muscle damage, and perceived exertion in trained CrossFit men: a randomized, double-blind, placebo-controlled crossover trial.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
acute caffeine supplementation | increase | glucose concentration | trained CrossFit men | +3.2 mmol/L, 95% CI: 2.1 to 4.3 vs. +1.5, 95% CI: -0.1 to 3.0 mmol/L, P=0.01 | resulted in higher glucose concentration after workout compared to PLA | #1 |
acute caffeine supplementation | no change | workout performance | trained CrossFit men | no differences were found between treatments | did not alter performance | #2 |
acute caffeine supplementation | no change | creatine kinase (CK) | trained CrossFit men | no differences were found between treatments | did not alter markers of muscle damage | #3 |
acute caffeine supplementation | no change | C-reactive protein | trained CrossFit men | no differences were found between treatments | did not alter markers of muscle damage | #4 |
acute caffeine supplementation | no change | muscle power | trained CrossFit men | no differences were found between treatments | did not alter power | #5 |
acute caffeine supplementation | no change | rating of perceived exertion (RPE) | trained CrossFit men | no differences were found between treatments | did not alter RPE | #6 |
acute caffeine supplementation | no change | muscle strength (handgrip strength) | trained CrossFit men | no differences were found between treatments | did not alter muscle strength | #7 |
acute caffeine supplementation | no change | delayed-onset muscle soreness (DOMS) | trained CrossFit men | no differences were found between treatments | did not alter delayed-onset muscle soreness | #8 |
BACKGROUND: Caffeine is a popular nutritional supplement among athletes. It is frequently used as an ergogenic aid to improve physical performance, delay fatigue, and increase muscle power. However, these effects have not been tested in CrossFit athletes. The aim of this study was to evaluate the effects of acute caffeine supplementation on workout performance, power, markers of muscle damage, and soreness in trained CrossFit men. METHODS: Nine men (28±2 years) with experience in CrossFit (2±0.3 years) were investigated in a randomized, double-blind, placebo-controlled crossover trial, with a 7-day washout between treatment periods. The athletes received anhydrous caffeine (CAF: 6 mg/kg body mass) or placebo (PLA) 60 minutes before a CrossFit workout with tasks that involved muscle strength, power, gymnastic movements, and metabolic conditioning. Blood samples were collected for creatine kinase (CK), C-reactive protein, and glucose determination. Workout performance, rating of perceived exertion (RPE), delayed-onset muscle soreness (DOMS), muscle strength (handgrip strength) and power (bench throw, jump squat and countermovement jump) were also evaluated. RESULTS: CAF resulted in higher glucose concentration after workout compared to PLA (+3.2 mmol/L, 95% CI: 2.1 to 4.3 vs. +1.5, 95% CI: -0.1 to 3.0 mmol/L, P=0.01). No differences were found between treatments in workout performance, CK, DOMS, RPE, muscle power and strength. CONCLUSIONS: Acute CAF supplementation did not alter performance, markers of muscle damage, power, and RPE in trained CrossFit men.