Casein Supplementation: Pre-Sleep vs. Post-Exercise

The Effects of Casein Supplementation Timing on Exercise Performance: A Comparison Between Pre-Sleep and Post-Exercise Intake

This randomized controlled trial aimed to investigate the effects of casein supplementation timing on post-exercise recovery and exercise performance in trained football players. Participants were allocated into three groups: pre-sleep casein ingestion, post-exercise casein ingestion, and control. The study compared the effects of pre-sleep and post-exercise casein intake on anaerobic performance, agility, and recovery markers following a standardized high-intensity resistance training session.

Study Overview

• Status: Completed
• Conditions: Athletic Performance
• Intervention / Treatment: Dietary supplement: Micellar Casein

Detailed Description

Casein is a slow-digesting protein commonly used as a dietary supplement to promote muscle recovery and adaptation. Although casein is traditionally consumed before sleep to maximize overnight muscle protein synthesis, limited evidence exists regarding the optimal timing of casein ingestion relative to exercise.

This study employed a randomized controlled experimental design to compare the effects of pre-sleep versus post-exercise casein supplementation on recovery and performance outcomes in trained football players. Twenty-four male participants were stratified by playing position (defender, midfielder, forward) and randomized into three groups: pre-sleep casein ingestion group (PSCIG), post-exercise casein ingestion group (PECIG), and control group (CG). All participants first completed a familiarization session and pre-test assessments, including the countermovement jump (CMJ), Illinois Agility Test, and Running-based Anaerobic Sprint Test (RAST).

After the pre-tests, all players performed a standardized high-intensity resistance training protocol designed to induce muscle fatigue. Participants in the PECIG consumed 30 g of micellar casein dissolved in 300 mL of water within 10-15 minutes post-exercise, while participants in the PSCIG consumed the same supplement 30-60 minutes before sleep. The control group did not receive any supplementation. Twenty-four ± 1 hours after the resistance training, post-tests were conducted using the same protocols as the pre-tests.

The primary aim of this study was to determine whether casein supplementation timing (pre-sleep vs. post-exercise) differentially influences recovery and subsequent anaerobic performance. Outcomes from this trial may provide practical recommendations for athletes and coaches regarding optimal protein supplementation strategies to enhance recovery and performance.

• Study Type: Interventional
• Enrollment (Actual): 24
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Gümüşhane Province
    • Gümüşhane, Gümüşhane Province, Turkey (Türkiye), 29100
      • Gumushane University, Faculty of Sport Sciences

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Male football players aged 18 to 25 years.
• At least three years of competitive soccer experience.
• Engaged in structured soccer training at least three times per week during the previous six months.
• Clearance to participate based on the Physical Activity Readiness Questionnaire (PAR-Q) (Thomas et al., 1992; Bredin et al., 2013).
• Provided written informed consent prior to participation.

Exclusion Criteria:

• Any musculoskeletal injury or surgery within the past six months.
• Reported milk or casein intolerance or allergy.
• Regular use of ergogenic supplements such as protein or creatine during the previous four weeks
• Medical conditions or limitations that could interfere with maximal exercise performance.
• Non-compliance with study procedures or training/testing protocols.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Pre-Sleep Casein Ingestion Group; Participants consumed 30 g of micellar casein dissolved in 300 mL of water 30-60 minutes before sleep following the standardized high-intensity resistance training session. Supplement intake was directly monitored by the research team to ensure compliance.	Dietary supplement: Micellar Casein; Participants consumed 30 g of micellar casein powder dissolved in 300 mL of water. Supplement timing varied by group: Post-Exercise Casein Ingestion Group (PECIG): Taken 10-15 minutes after completing the standardized high-intensity resistance training session. Pre-Sleep Casein Ingestion Group (PSCIG): Taken 30-60 minutes before bedtime on the same day as the training session. The control group received no supplementation. All supplements were prepared and monitored by the research team to ensure dosage accuracy and participant compliance.
Experimental: Post-Exercise Casein Ingestion Group; Participants consumed 30 g of micellar casein dissolved in 300 mL of water 10-15 minutes after completing the standardized high-intensity resistance training session. Supplement preparation and intake were supervised by the research team.	Dietary supplement: Micellar Casein; Participants consumed 30 g of micellar casein powder dissolved in 300 mL of water. Supplement timing varied by group: Post-Exercise Casein Ingestion Group (PECIG): Taken 10-15 minutes after completing the standardized high-intensity resistance training session. Pre-Sleep Casein Ingestion Group (PSCIG): Taken 30-60 minutes before bedtime on the same day as the training session. The control group received no supplementation. All supplements were prepared and monitored by the research team to ensure dosage accuracy and participant compliance.
No Intervention: Control Group; Participants completed the standardized high-intensity resistance training protocol but did not receive any supplementation.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Peak Power (RAST Test)	Peak power will be calculated using body mass and sprint times obtained during the RAST test to assess maximal anaerobic performance. Measurements will be taken at baseline and 24 hours post-training.	Change from baseline (pre-test) to 24 hours post-training (post-test)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean Power (RAST Test)	Mean power will be calculated from total sprint time and body mass during the Running-based Anaerobic Sprint Test (RAST) to evaluate anaerobic endurance performance. Measurements will be collected pre- and 24 hours post-training.	Change from baseline (pre-test) to 24 hours post-training (post-test)
Fatigue Index (RAST Test)	Fatigue index will be calculated using the difference between the highest and lowest sprint times divided by the total sprint time during the RAST test. It reflects fatigue and recovery capacity. Measurements will be collected pre- and 24 hours post-training.	Change from baseline (pre-test) to 24 hours post-training (post-test)
Countermovement Jump (CMJ) Height	CMJ height will be measured using a validated jump mat system to assess lower-limb explosive power. Measurements will be collected pre- and 24 hours post-training under standardized conditions.	Change from baseline (pre-test) to 24 hours post-training (post-test)
Illinois Agility Test Time	Agility performance will be assessed using the Illinois Agility Test to evaluate change of direction speed and overall agility. Measurements will be collected pre- and 24 hours post-training under standardized environmental conditions.	Change from baseline (pre-test) to 24 hours post-training (post-test)

Collaborators and Investigators

• Sponsor: Serdar Bayrakdaroğlu

Study record dates

Study Major Dates

• Study Start (Actual): March 10, 2025
• Primary Completion (Actual): March 14, 2025
• Study Completion (Actual): March 14, 2025

Study Registration Dates

• First Submitted: September 5, 2025
• First Submitted That Met QC Criteria: September 5, 2025
• First Posted (Estimated): September 12, 2025

Study Record Updates

• Last Update Posted (Estimated): September 12, 2025
• Last Update Submitted That Met QC Criteria: September 5, 2025
• Last Verified: September 1, 2025

More Information

Terms related to this study

• Keywords: Casein Supplementation; Pre-Sleep Protein Intake; Post-Exercise Protein Intake; Muscle Recovery; Anaerobic Performance
• Other Study ID Numbers: GTU-2025-CASEIN01; Ethics Committee -GTU-EC-2024 (Other Identifier: Gumushane University)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared because of privacy concerns and restrictions imposed by the ethics committee approval.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No