Pre-Sleep vs. Post-Workout Protein: A New Study on What Really Matters for Gains

You just crushed a heavy training session. What's the first thing you think about? For many, it's slamming a protein shake to capitalize on the so-called "anabolic window." Others argue that a slow-digesting protein before bed is the real secret to maximizing recovery and growth.

This debate over protein timing has been a staple in gyms for decades. But what does the science actually say, especially for older adults who are new to lifting?

A new study published in the Journal of the International Society of Sports Nutrition puts these two popular strategies head-to-head. The results challenge some long-held beliefs and force us to reconsider what truly drives progress.

Disclaimer: This article is a review of the study's abstract, as the full text was not available. The analysis is based on the information provided in the abstract alone.

The Study: Pitting Post-Workout vs. Pre-Sleep Protein

Researchers wanted to see if the timing of a 40-gram protein supplement could enhance muscle and strength gains in older men starting a resistance training program.

Here’s a quick breakdown of the setup:

• Who: Thirty untrained men with an average age of around 66 years.
• What: They all participated in a 12-week supervised resistance training program, hitting the gym twice per week.
• The Groups: The men were randomly assigned to one of three groups:
  1. Post-Exercise Protein (PRP): Consumed 40g of protein immediately after their workouts.
  2. Pre-Sleep Protein (PSP): Consumed 40g of protein right before bed.
  3. Resistance Exercise Training Only (RETO): Followed the training program with no specific protein supplement timing.

Researchers measured changes in quad muscle thickness (vastus lateralis, rectus femoris, and vastus intermedius) and 1-repetition max (1-RM) on the leg press and chest press at the start, week 6, and week 12.

The Results: Training is King

First, the good news: resistance training works. Every single participant, regardless of group, saw significant improvements in both muscle size and strength over the 12 weeks.

Here’s a look at the average gains across all groups:

• Muscle Thickness:
  • Vastus Lateralis: +0.16 cm
  • Rectus Femoris: +0.13 cm
  • Vastus Intermedius: +0.18 cm
• Strength:
  • Chest Press 1-RM: +10.9 kg
  • Leg Press 1-RM: +28.3 kg

These are solid, meaningful gains for anyone, especially for older adults new to lifting. But here's the kicker...

There were no significant differences between the groups.

That’s right. The group drinking a protein shake after training, the group drinking one before bed, and the group that did neither all made similar progress. The extra 40 grams of strategically-timed protein didn't move the needle on muscle growth or strength gains compared to just doing the training program.

Why Didn't Protein Timing Matter?

The study's conclusion offers a crucial piece of context: the participants already had an adequate daily protein intake, consuming at least 1.0 g/kg of body weight per day before any supplementation.

This suggests a hierarchy of importance:

1. Consistent, Progressive Resistance Training: This is the primary driver of adaptation.
2. Total Daily Protein Intake: Hitting your daily protein target is the next most critical factor.
3. Nutrient Timing: This appears to be far less important, especially when the first two conditions are met.

For these untrained older men, the powerful stimulus of a new training program combined with sufficient overall protein was enough to maximize their gains. Adding a precisely timed 40g shake on top of that provided no extra benefit.

Practical Takeaways for Lifters and Coaches

This study provides some clear, actionable insights, even if we can't generalize them to every population.

1. Master the Basics First: Before you worry about the anabolic window or pre-sleep casein, make sure your (or your client's) training is consistent and total daily protein intake is sufficient. These are the big rocks that build the foundation of your results.

2. Context is Crucial: These findings are specific to untrained older men. The needs of a 25-year-old competitive athlete training 5-6 days a week might be different. However, this study serves as a powerful reminder that we shouldn't blindly apply sports nutrition dogmas to every individual.

3. Use Timing for Convenience, Not for Magic: Does a post-workout shake help you hit your daily protein goal? Great, keep doing it. Does a pre-sleep protein source help you feel full and recovered? Perfect. The takeaway isn't that timing is useless, but that its primary benefit may be in helping you achieve your total daily intake, rather than providing a unique anabolic advantage on its own.

Ultimately, the real winner in this study was resistance training itself. It proves yet again that a structured lifting program is the most potent tool we have for building stronger, more muscular bodies at any age.

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Reference:

Klemp AO, Ormsbee MJ, Yeh M, et al. Neither pre-sleep nor post-exercise protein consumption influences resistance exercise training adaptations in older adults. Journal of the International Society of Sports Nutrition. 2025. https://pubmed.ncbi.nlm.nih.gov/40539259/