Dose-response effects of caffeine during repeated cycling sprints in normobaric hypoxia to exhaustion.
Study Goal
The researchers aimed to determine the optimal caffeine dose (low, moderate, or high) for enhancing repeated cycling sprint ability in hypoxia.
Results Summary
Moderate (6 mg/kg) and high (9 mg/kg) caffeine doses improved total sprint number and work done compared to placebo, with no significant differences between the two doses. Blood lactate concentration increased with moderate and high doses, but power outputs and perceived exertion remained unchanged across doses.
Population
Twelve active males
Effective Dosage
3 mg/kg (LOW), 6 mg/kg (MOD), 9 mg/kg (HIGH), ingested once 1 hour before exercise
Duration
Single-dose intervention per trial, with four separate visits
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
caffeine capsules (6 mg/kg) | increase | total sprint number | twelve active males | 20 ± 7 vs. 13 ± 4 | was greater | #1 |
caffeine capsules (9 mg/kg) | increase | total sprint number | twelve active males | 18 ± 8 vs. 13 ± 4 | was greater | #2 |
caffeine capsules (6 mg/kg) | increase | total sprint number | twelve active males | 20 ± 7 vs. 15 ± 6 | was higher | #3 |
caffeine capsules (6 mg/kg) | increase | total work done | twelve active males | 111 ± 40 kJ vs. 83 ± 29 kJ and 76 ± 25 kJ | was greater | #4 |
caffeine capsules (9 mg/kg) | increase | total work done | twelve active males | 100 ± 35 kJ vs. 83 ± 29 kJ and 76 ± 25 kJ | was greater | #5 |
caffeine capsules (6 mg/kg vs 9 mg/kg) | no change | total sprint number | twelve active males | - | no significant differences | #6 |
caffeine capsules (6 mg/kg vs 9 mg/kg) | no change | total work done | twelve active males | - | no significant differences | #7 |
caffeine capsules (6 mg/kg) | increase | blood lactate concentration | twelve active males | - | was higher | #8 |
caffeine capsules (9 mg/kg) | increase | blood lactate concentration | twelve active males | - | was higher | #9 |
caffeine capsules (3 mg/kg, 6 mg/kg, 9 mg/kg) | no change | peak power outputs | twelve active males | - | did not differ | #10 |
caffeine capsules (3 mg/kg, 6 mg/kg, 9 mg/kg) | no change | mean power outputs | twelve active males | - | did not differ | #11 |
caffeine capsules (3 mg/kg, 6 mg/kg, 9 mg/kg) | no change | fatigue index | twelve active males | - | did not differ | #12 |
caffeine capsules (3 mg/kg, 6 mg/kg, 9 mg/kg) | no change | ratings of perceived exertion | twelve active males | - | did not differ | #13 |
PURPOSE: With limited studies exploring the dose-response of caffeine consumption on repeated sprint ability in hypoxia, this study aimed to determine the optimal caffeine dose (low, moderate or high) during repeated sprints in hypoxia to exhaustion. METHODS: On separate visits, twelve active males randomly performed four experimental trials in normobaric hypoxia (inspired oxygen fraction: 16.5 ± 0.2%). Participants ingested placebo (PLA) or caffeine capsules (3, 6 or 9 mg/kg or LOW, MOD and HIGH, respectively) 1 h before exercise and then underwent a repeated cycling sprint test (10 s sprint/20 s active recovery) to exhaustion. Total sprint number and work done, peak and mean power output, blood lactate concentration, cardiorespiratory and perceptual responses were recorded. RESULTS: Total sprint number was greater in MOD and HIGH compared to PLA (20 ± 7 and 18 ± 8 vs. 13 ± 4; all P < 0.05), with MOD also higher than LOW (15 ± 6; P = 0.02). Total work done was greater in MOD (111 ± 40 kJ) and HIGH (100 ± 35 kJ) compared to LOW (83 ± 29 kJ) and PLA (76 ± 25 kJ) (all P < 0.05). However, there were no significant differences in total sprint number or total work done between MOD and HIGH (all P > 0.05). Blood lactate concentration was higher in both MOD and HIGH compared to PLA (all P < 0.05). However, peak and mean power outputs, fatigue index, and ratings of perceived exertion did not differ across different caffeine dosages (all P > 0.05). CONCLUSION: A moderate dose of caffeine (6 mg/kg) is the optimal amount for enhancing repeated cycling sprint ability when compared to low and high doses in moderate normobaric hypoxia.