Napping, Caffeine, and Their Combination Enhanced Explosivity and Repeated-Sprint Performance: A Randomized...

Area of Science:

• Sports Science
• Human Performance
• Sleep Research

Background:

• Afternoon fatigue and reduced cognitive/physical performance are common.
• Napping and caffeine are known countermeasures, but their combined effects on evening performance require further investigation.
• Understanding these effects is crucial for athletes competing in evening events.

Purpose of the Study:

• To investigate the independent and combined effects of an early afternoon nap and moderate-dose caffeine on afternoon alertness and evening physical performance.
• To assess impacts on reaction time, sleepiness, agility, and explosive power.

Main Methods:

• A randomized, counterbalanced, double-blind, placebo-controlled study involving 13 physical education students.
• Four conditions were tested: placebo, nap (90-min), caffeine (5 mg/kg), and nap plus caffeine.
• Assessments included reaction time, Epworth Sleepiness Scale, jumping performance (squat jump, countermovement jump), and repeated modified agility test.

Main Results:

• Neither caffeine, napping, nor their combination significantly affected subjective sleepiness or reaction times.
• All interventions improved squat jump performance compared to placebo, with the nap plus caffeine combination showing the greatest enhancement.
• The nap plus caffeine combination significantly improved explosive power (take-off velocity, relative power) compared to nap or caffeine alone.

Conclusions:

• Napping and caffeine independently enhance repeated agility and explosive power.
• The combination of napping and caffeine further boosts explosive power, beneficial for evening team and racket sports competitions.
• Limited effects on non-explosive tasks and potential sleep disruption suggest constraints on broader application.