The effect of high-intensity interval training and caffeine supplementation on exercise adaptations and ergogenicity of acute caffeine intake in young men

Determining the effect of high-intensity interval training and caffeine supplementation on exercise performance and adaptations as well as ergogenicity of acute caffeine intake

double-blind, placebo-controlled, and randomized-controlled experimental design. n = 80, 20 in each group. After matching based on age, weight and V̇O2max, participants were randomized on a 1:1:1:1 basis to one of four groups. Phase 4

Eighty physically inactive men participated in a parallel, double-blind, placebo-controlled trial conducted in Istanbul, Turkey. Based on age, height, body mass and maximal oxygen consumption, the participants were assigned to 4 groups (n = 20 each): caffeine supplementation, caffeine supplementation + exercise training, placebo and placebo + exercise training. High-intensity interval training (HIT) was performed 5 times per week for 8 weeks. Caffeine supplementation (3 mg/kg/day) was started at the same time as the HIT. Data collection was done in 4 stages: pre-test, mid-test, post-test, and delayed post-test, each consisting of two separate experiment sessions (3 mg/kg of caffeine or placebo). In each experiment session, 45 min after consuming a placebo or caffeine, a 3-km running test was performed at first, followed by a Wingate power test with 20 min rest between assessments.

Inclusion criteria: healthy; inactive; lack of caffeine dependence Exclusion criteria: caffeine habituation; taking medicine or supplements

Caffeine supplementation (3mg/kg/day) for 8 weeks. Cellulose intake (200mg/day) for 8 weeks. Caffeine supplementation (3mg/kg/day) + high-intensity interval training for 8 weeks. Cellulose intake (200mg/day) + high-intensity interval training for 8 weeks.

3-km running performance; power outputs; rate of perceived exertion; V̇O2max; body composition

To minimize possible group differences, first, the participants were categorized according to age, body mass, and V̇O2max. Then, the subjects of each category were randomized on a 1:1:1:1 basis to one of four groups: caffeine supplementation, caffeine supplementation + exercise training, placebo and placebo + exercise training.

Preparation of the supplement/placebo was done by someone outside the study. Also, all participants received capsules containing caffeine/placebo in the same appearance and weight for the same duration and frequency. In addition, for statistical analysis, the titles of the groups were not clear and only the numbers 1 to 4 were assigned to the groups.