Casein Supplementation Timing and Exercise Performance in Soccer Players: Pre-Sleep vs. Post-Exercise Intake-A Randomized Controlled Trial.

2025-12-17
Nutrients 17(24)
- Serdar Bayrakdaroğlu
- Zeynep Hazal Ateş
- Halil İbrahim Ceylan
- Murat Kul
- Raul Ioan Muntean
- Wissem Dhahbi

PubMed: 41470882
DOI: 10.3390/nu17243938

Study Design

Type: Randomized Controlled Trial (RCT)
Population: Twenty-four highly trained male soccer players (mean age: 20.6 ± 1.8 years)
Methods: randomly assigned to three groups: post-exercise casein ingestion group (PECIG; n = 8), pre-sleep casein ingestion group (PSCIG; n = 8), and control group (CG; n = 8). Following a standardized high-intensity resistance training protocol, participants consumed 30 g of micellar casein dissolved in 300 mL of water either immediately after exercise or 30-60 min before bedtime. Performance was assessed using the Countermovement Jump (CMJ), the Illinois Agility Test (IAT), and the Running-based Anaerobic Sprint Test (RAST), which were conducted both before and 24 h after the training session.
Blinding: Open-label
Duration: 24 h
Funding: Unclear

Rigorous Journal

Background: Nutrient timing strategies may influence recovery and performance in athletes; however, the effects of ingesting casein protein before sleep versus immediately after exercise remain unclear. This study compared the acute effects of pre-sleep and post-exercise ingestion of casein on high-intensity anaerobic performance in highly trained soccer players. Methods: Twenty-four highly trained male soccer players (mean age: 20.6 ± 1.8 years) were randomly assigned to three groups: post-exercise casein ingestion group (PECIG; n = 8), pre-sleep casein ingestion group (PSCIG; n = 8), and control group (CG; n = 8). Following a standardized high-intensity resistance training protocol, participants consumed 30 g of micellar casein dissolved in 300 mL of water either immediately after exercise or 30-60 min before bedtime. Performance was assessed using the Countermovement Jump (CMJ), the Illinois Agility Test (IAT), and the Running-based Anaerobic Sprint Test (RAST), which were conducted both before and 24 h after the training session. Results: Repeated-measures ANOVA revealed significant group-by-time effects for CMJ (F = 8.21, p = 0.002, η²p = 0.36) and RAST performance variables, including peak power (F = 6.94, p = 0.003, η²p = 0.32), mean power (F = 7.42, p = 0.002, η²p = 0.34), and fatigue index (F = 5.87, p = 0.008, η²p = 0.28). Post hoc analyses showed that PSCIG significantly improved CMJ (Δ = +1.45 cm; p < 0.001, d = 2.04) and RAST mean power (Δ = +125.14 W; p = 0.002, d = 1.55) compared with the control condition. PECIG significantly enhanced RAST peak power (Δ = +205.79 W; p = 0.001, d = 1.64), mean power (Δ = +128.43 W; p = 0.013, d = 1.24), and fatigue index (Δ = +4.12 W/s; p = 0.010, d = 1.29) relative to CG. No performance differences were observed between PSCIG and PECIG timing conditions (all p > 0.05). Conclusions: Both pre-sleep and post-exercise casein ingestion enhanced anaerobic performance in highly trained soccer players, with each timing method favoring different performance outcomes. However, neither strategy demonstrated superiority over the other, suggesting that casein timing may be flexibly applied according to athletes' preferences and training contexts.

Research Insights

Casein Protein→Improved Agility Performance
Repeated-measures ANOVA revealed significant group-by-time effects for CMJ (F = 8.21, p = 0.002, η²p = 0.36) and RAST performance variables, including peak power ... mean power ... and fatigue index ... No performance differences were observed between PSCIG and PECIG timing conditions (all p > 0.05).
Effect
Neutral
Effect size
Small
Dose
30 g dissolved in 300 mL of water
Casein Protein→Improved Anaerobic Power
PECIG significantly enhanced RAST ... mean power (Δ = +128.43 W; p = 0.013, d = 1.24) ... relative to CG.
Effect
Beneficial
Effect size
Large
Dose
30 g dissolved in 300 mL of water
Casein Protein→Improved Jump Height
Post hoc analyses showed that PSCIG significantly improved CMJ (Δ = +1.45 cm; p < 0.001, d = 2.04) ... compared with the control condition.
Effect
Beneficial
Effect size
Large
Dose
30 g dissolved in 300 mL of water
Casein Protein→Reduced Fatigue Index
PECIG significantly enhanced RAST ... fatigue index (Δ = +4.12 W/s; p = 0.010, d = 1.29) relative to CG.
Effect
Beneficial
Effect size
Large
Dose
30 g dissolved in 300 mL of water