Effects of Afternoon Napping, Caffeine, and Standardised Active Recovery on Evening Athletic Performance

Effects of Afternoon Napping, Caffeine, and a Standardised Active Recovery Protocol on Evening Athletic Performance According to Sex and Chronotype: A Randomised Crossover Trial

This study evaluated whether afternoon napping, caffeine ingestion, and a standardised active recovery and nutritional protocol could influence evening physical and cognitive performance in healthy university athletes.

Participants completed five experimental conditions in a randomised crossover design: placebo without napping, napping with placebo, caffeine without napping, napping combined with caffeine, and napping combined with caffeine plus a standardised active recovery and nutritional protocol. The nap opportunity lasted 90 minutes and caffeine was administered at 5 mg/kg body mass.

The main outcome was repeated agility performance. Additional outcomes included sprint performance, jumping performance, reaction time, subjective sleepiness, sleep characteristics during the nap opportunity, and selected physiological measures. The study also explored whether responses differed according to sex and chronotype.

This randomised, placebo-controlled crossover study examined the isolated and combined effects of afternoon napping, caffeine ingestion, and a standardised active recovery and nutritional protocol on evening athletic performance.

Participants completed five experimental conditions in a counterbalanced Latin-square order, with at least 72 h between sessions:

1. PLA: placebo capsule at 18:00, without a nap opportunity.
2. NAP: 90-min nap opportunity from 13:00 to 14:30 plus placebo capsule at 18:00.
3. CAF: caffeine ingestion at 18:00 (5 mg/kg body mass) without a nap opportunity.
4. NAP+CAF: 90-min nap opportunity plus caffeine ingestion at 18:00.
5. NAP+CAF+REC: 90-min nap opportunity plus caffeine ingestion at 18:00 and a standardised active recovery and nutritional protocol from 18:45 to 19:00.

The active recovery and nutritional protocol included a standardised lower-limb dynamic stretching routine followed by a carbohydrate-protein snack containing 20 g maltodextrin and 10 g whey isolate. The protocol was identical for all participants allocated to this condition.

Participants were stratified by sex and chronotype before condition allocation. Capsule allocation was double-blinded: participants, outcome assessors, and the testing team were unaware of whether caffeine or placebo had been administered. Blinding of nap and active recovery components was not possible because of the nature of these interventions.

The primary outcome was total time during the Repeated Modified Agility Test. Secondary performance outcomes included 20-m sprint time, countermovement jump height, squat jump height, simple reaction time, choice reaction time, and subjective sleepiness. Nap sleep characteristics were assessed using portable electroencephalographic monitoring. Physiological measures included heart-rate variability, salivary cortisol, plasma brain-derived neurotrophic factor, and blood lactate.

All sessions were conducted under standardised sleep, dietary, and activity-control procedures. The study explored whether intervention responses differed by sex and chronotype.

Inclusion Criteria:

• Healthy university athletes aged 18-25 years.
• Regular engagement in structured training, defined as at least 10 training sessions per week of approximately 2 h each, across team sports, judo, athletics, tennis, or swimming.
• Non-habitual napping, defined as fewer than one nap per week.
• Low habitual caffeine intake, defined as <80 mg/day, assessed using a 7-day dietary recall.
• Non-smoker and free from regular medication or recreational drug use.
• No musculoskeletal injury during the preceding month.
• Good self-reported sleep quality, defined as a Pittsburgh Sleep Quality Index score <5.
• Definite morning chronotype (MEQ score 59-86) or definite evening chronotype (MEQ score 16-41).
• For female participants: self-reported regular menstrual cycles (26-32 days), no hormonal contraceptive use, and no self-reported history of menstrual disorders.

Exclusion Criteria:

• Intermediate chronotype (MEQ score 42-58).
• Habitual napping (≥1 nap per week).
• Habitual caffeine intake ≥80 mg/day.
• Smoking, regular medication use, or recreational drug use.
• Musculoskeletal injury during the preceding month.
• Pittsburgh Sleep Quality Index score ≥5.
• Self-reported irregular menstrual cycles, hormonal contraceptive use, or history of menstrual disorders in female participants.
• Self-reported sleep disorder.
• Inability or unwillingness to complete all five experimental conditions.