The effects of a caffeine containing pre-workout supplement on β
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
caffeine containing multi-ingredient pre-workout supplement | increase | Epinephrine | ten resistance-trained males | 323 ± 34 vs 457 ± 68 pmol/l | increased | #1 |
caffeine containing multi-ingredient pre-workout supplement | increase | Epinephrine | ten resistance-trained males | 5140 ± 852 vs 2862 ± 498 pmol/l | was greatest at POST | #2 |
caffeine containing multi-ingredient pre-workout supplement | increase | p-β | ten resistance-trained males | 2.5-fold | increased | #3 |
caffeine containing multi-ingredient pre-workout supplement | increase | performance | ten resistance-trained males | - | improves | #4 |
caffeine containing multi-ingredient pre-workout supplement | increase | pre-exercise catecholamines | ten resistance-trained males | - | increases | #5 |
caffeine containing multi-ingredient pre-workout supplement | no change | acute myocellular signaling responses | ten resistance-trained males | - | were largely similar | #6 |
AIM: The acute myocellular responses of caffeine supplementation during resistance exercise (RE) have not been investigated. β PURPOSE: Elucidate the effects of pre-workout supplementation on signaling responses to an acute RE bout. METHODS: In a randomized, counter-balanced, double-blind, placebo-controlled, within-subject crossover study, ten resistance-trained males (mean ± SD; age = 22 ± 2.4 years, height = 175 ± 7 cm, body mass = 84.1 ± 11.8 kg) consumed a caffeine containing multi-ingredient pre-workout supplement (SUPP) or color and flavor matched placebo (PL) 60 min prior to an acute RE bout of barbell back squats. Pre- and post-exercise muscle biopsies were analyzed for the phosphorylation (p-) of β RESULTS: Epinephrine increased at PRE in SUPP (mean ± SE: 323 ± 34 vs 457 ± 68 pmol/l; p = 0.028), and was greatest at POST in the SUPP condition compared to PL (5140 ± 852 vs 2862 ± 498 pmol/l; p = 0.006). p-β CONCLUSION: Consumption of a caffeine containing pre-workout supplement improves performance, possibly through increases in pre-exercise catecholamines. However, the acute myocellular signaling responses were largely similar post-exercise.