No, muscle does not only grow on rest days. Muscle growth occurs during the rest period after a workout, when your body is repairing the damage that was done during the set. This process is called muscle protein synthesis.

During a workout, your muscles are broken down. This damage is necessary for muscle growth. However, if you don’t give your muscles time to repair the damage, they won’t be able to grow.

That’s why it’s important to rest for enough time between sets. The amount of time you need to rest will depend on the intensity of your workout. For example, if you’re doing a high-intensity workout, you’ll need to rest for longer than if you’re doing a low-intensity workout.

However, muscle growth does continue on workout days. This is because your body is still repairing the damage that was done during the workout. However, muscle growth is less efficient on workout days than it is on rest days.

So, to answer your question, 1 or 2 hours a day does affect muscle growth enough to need rest days. Muscle growth is still happening on workout days, but it is less efficient. This is why it is important to give your muscles time to rest and recover.

Here are some tips for maximizing muscle growth:

• Lift weights that are challenging but allow you to complete all the reps.

• Focus on compound exercises: Compound exercises work multiple muscle groups at once. This is a more efficient way to build muscle than isolation exercises, which only work one muscle group at a time.

• Progressive overload: Progressive overload is the key to muscle growth. This means gradually increasing the weight you are lifting or the number of reps you are doing over time.

• Take short rests between sets: Aim to rest for 30-60 seconds between sets.

• Progress gradually: As you get stronger, you can increase the weight you are lifting.

• Be patient: It takes time to build muscle. Don’t expect to see results overnight.

By following these tips, you can maximize muscle growth and reach your fitness goals.