Muscle growth, also known as hypertrophy, is the result of your muscles adapting and growing in response to the stress of exercise. When you lift weights or do resistance training, you’re essentially causing small tears and damage to your muscle fibers. Your body then repairs these tears and rebuilds the muscles bigger and stronger than before. This is how you get bigger and stronger muscles over time.
An important part of the muscle building process is adequate rest between workouts to allow your muscles to fully recover and repair themselves. So how many days of rest should you have between strength training sessions for optimal muscle growth? There are a few factors to consider when determining the ideal rest days for muscle growth.
Muscle Protein Synthesis
When you strength train, it initiates muscle protein synthesis (MPS) which is the process of building new muscle tissue. MPS is elevated for 24-48 hours after you train as your body synthesizes new muscle proteins to repair and rebuild the damaged muscle fibers. During this time, muscles are sensitive to nutrition and respond well to protein intake.
After about 48 hours, MPS returns to baseline levels. Therefore, you want to ensure you are training again within 48 hours to take advantage of this window of increased protein synthesis. Research shows that muscle protein turnover is optimized when training sessions are spaced about 48 hours apart.
Muscle Recovery
In addition to MPS, adequate rest is needed to allow your muscles time to fully recover between training sessions. When you strength train, it causes microscopic tears in the muscle fibers. It takes time for these small injuries to heal. If you train again too soon, you can aggravate these injuries and hinder muscle growth.
Studies show it takes approximately 72 hours for your muscles to fully recover after a strength training session. This allows the muscle tears to heal completely so you can train consistently without excessive soreness or fatigue.
Overtraining
Overtraining is another concern when you don’t rest enough between workouts. Overtraining occurs when your body is not given sufficient time to recover and adapt between training sessions.
Signs of overtraining include:
- Decreased performance
- Persistent muscle soreness
- Increased risk of injury
- Fatigue and lack of energy
- Insomnia
- Loss of motivation
- Depression
Overtraining can actually hinder muscle growth and strength gains. Without proper rest, your body cannot keep up with repairing and building muscle tissue. That’s why adequate recovery time is crucial.
Muscle Groups Trained
Another factor is which muscle groups you trained in your last session. Large muscle groups like your legs and back require more recovery time than smaller groups like arms and shoulders.
Research shows muscles trained with high volume, such as multiple sets of squats and deadlifts, may require 5-7 days of rest between sessions. While smaller muscle groups like biceps can recover more fully in just 2-3 days.
Volume and Intensity
Your training volume and intensity will also impact how much rest you need. Volume refers to the total number of reps and sets you do per muscle group. Intensity is how heavy you are lifting relative to your 1 rep max.
Higher training volumes and heavier loads require longer recovery periods versus lighter, lower volume sessions. Make sure to adjust your rest days based on your programming and whether you are training closer to muscular endurance or maximum strength.
Your Age
Older adults may require slightly more recovery time compared to younger athletes due to physiological differences. However, the basics remain the same at any age – muscles need at least 48 hours to synthesize new proteins and roughly 72 hours to fully recover between strength sessions.
Nutrition and Lifestyle Factors
Proper nutrition can support faster muscle recovery. Make sure you are eating enough protein and calories to fuel muscle growth. Get adequate sleep, as most muscle repair occurs during sleep. Manage your stress levels, as high cortisol can hinder recovery. Stick to smart programming that has built-in recovery days to avoid overtraining.
Recommended Rest Days
Based on the research, here are some general recommendations for rest days between strength training sessions for optimal muscle growth:
- 48 hours between sessions for the same muscle groups
- 72 hours for full recovery of trained muscle groups
- 5-7 days for major muscle groups trained with high volume like legs
- Adjust volume and intensity if doing total body workouts to allow for adequate recovery
For a typical “bodybuilder” split hitting each muscle group once per week, you would follow something like this:
| Monday: | Chest |
| Tuesday: | Back |
| Wednesday: | Rest |
| Thursday: | Shoulders |
| Friday: | Arms |
| Saturday: | Legs |
| Sunday: | Rest |
This allows at least 48 hours between training each muscle group again. Legs get 5 days of rest after the high volume of compound lifts like squats and deadlifts. You can customize your split based on your own recovery capacity and which muscle groups you want to prioritize.
Listen to Your Body
While these rest day recommendations are evidence-based guidelines, always listen to your body and understand your own recovery needs. If you are still very sore or fatigued, take an extra day of rest. Recognize the signs of overtraining and be willing to take a deload week if needed. Get sufficient sleep, nutrition and manage life stresses as well.
Conclusion
To maximize muscle growth from strength training, make sure you are providing your muscles adequate recovery time between sessions. Shoot for at least 48 hours of rest for the same muscle groups to optimize muscle protein synthesis. Allow 72 hours for full recovery of trained muscles. Adjust volume and intensity appropriately to prevent overtraining. Follow a smart training split that spaces workouts by muscle groups across the week. Rest days are just as crucial as training days when building muscle, so use recovery time productively.
