Effects of Creatine and Caffeine Supplementation During Resistance Training on Body Composition, Strength, Endurance, Rating of Perceived Exertion and Fatigue in Trained Young Adults.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 33759701 · doi:10.1080/19390211.2021.1904085
What was done
Twenty-eight trained young adults were randomized into four groups for a 6-week resistance training intervention with pre-workout supplementation: creatine plus caffeine (CR-CAF; n = 9; 0.1 g·kg⁻¹·d⁻¹ creatine monohydrate + 3 mg·kg⁻¹·d⁻¹ caffeine anhydrous), creatine alone (CR; n = 7; 0.1 g·kg⁻¹·d⁻¹ creatine + 3 mg·kg⁻¹·d⁻¹ micronized cellulose), caffeine alone (CAF; n = 6; 3 mg·kg⁻¹·d⁻¹ caffeine + 0.1 g·kg⁻¹·d⁻¹ maltodextrin), or placebo (PLA; n = 6; 0.1 g·kg⁻¹·d⁻¹ maltodextrin + 3 mg·kg⁻¹·d⁻¹ micronized cellulose) taken one hour prior to training. Pre- and post-intervention assessments measured fat-free and fat mass (air-displacement plethysmography), muscle thickness of elbow and knee flexors and extensors (ultrasound), 1-repetition maximum (1-RM) strength for leg press and chest press, and muscular endurance (repetitions to fatigue at 50% baseline 1-RM).
What was found
A significant group x time interaction occurred for knee extensor muscle thickness (p = 0.049), with the creatine-only group demonstrating an increase over time and no changes observed in the other three groups. The abstract reported no other between-group differences for any other measured variable; specific numerical values, means, and effect sizes were not reported in the abstract.
Why it matters
The findings indicate that co-ingesting caffeine with creatine does not produce additive gains in strength, endurance, or muscle accretion during resistance training, and may blunt isolated creatine-induced increases in muscle thickness.
Limits
The sample size was extremely small (6 to 9 participants per arm), leaving the trial underpowered to detect modest differences between groups. The duration was relatively short (6 weeks), the population was limited to young trained adults, and outcomes for perceived exertion and fatigue mentioned in the title were not detailed in the abstract.
Cited by
- supports A training study conducted by Darren Candow's group found that concurrent caffeine and creatine supplementation interfered with creatine's training benefits.