Effects of low-dose caffeine supplementation on early morning performance in the standing shot put throw

Abstract

The purpose of the present investigation was to assess the efficacy of low-dose caffeine use for early morning performance in the shot put event. A double-blind, randomized, crossover design was used to investigate the effects of buccal caffeine supplementation on early morning shot put execution in nine inter-collegiate track and field athletes. In one condition the participants received a piece of caffeinated gum designed to deliver 100 mg of caffeine in a buccal manner, and in a second condition a placebo gum. The gum was chewed for 5 min before being discarded. Participants then completed the first psychomotor vigilance task followed by a series of five warm-up throws, followed by six attempts with a shot put (7.26 kg for males, 4.0 kg for females) measured for distance. The protocol ended with a final psychomotor vigilance task. A repeated-measures analysis of variance (treatment*time) was used to compare performance between the caffeine and placebo treatments over the six measured attempts. A significant difference (treatment×throw) was observed (P=0.030, partial eta-squared = 0.259), indicating that the caffeine treatment produced better performance over the course of the six attempts subsequent to a warm-up. A paired samples t-test (Bonferroni-adjusted for multiple comparisons) revealed that the first attempt in the caffeine treatment (9.62±1.71 m) and in the placebo treatment (9.05±1.69 m) were significantly different (P = 0.050, effect size = 0.996, 95%CI 1.02 to 0.13 m). Repeated-measures analysis of covariance revealed a significant (P=0.016, partial eta-squared = 0.650) interaction effect (treatment×mean reaction time), whereby both at the pre and post time points the mean reaction time on the psychomotor vigilance task was reduced under the caffeine treatment (caffeine: pre 0.306±0.05 s, post 0.316±0.08 s; placebo: pre 0.317±0.06 s, post 0.323±0.06 s). Based on these results, we suggest that caffeine gum can be beneficial for both performance and alertness if used by shot put athletes during early morning sessions.

Keywords:

• Caffeine
• shot put
• reaction time
• time of day