How long of a break should I take before working the same muscle group?

It is recommended that you strength-train your muscles at least two times per week. Strength training is the process of building and maintaining muscles in the body by using progressively heavier weights (or resistance). Rest at least one to two days in between working the same muscle groups again. For example, if you work your arm muscles on Monday, wait until Wednesday or Thursday to work them again. Small tears in the muscles occur during strength training. Rest is needed to allow the muscles to repair themselves, which is how they become bigger and stronger.

The amount of rest needed between strength training days for a given muscle group depends on your program goal and your level of experience. If you are a beginner trying to lose weight, it is recommended to begin with resistance training which emphasizes stabilization. This type of training uses intensities of between 50%-70% of a 1 repetition maximum for up to 20 repetitions. This type of training can be done from 2 to 4 times per week; a 24 hour rest period is sufficient. If you are more experienced and have a goal of increasing muscle size you should use an intensity of 75%-85% of your 1 repetition maximum for 6 to 12 repetitions and 3 to 5 sets. This type of training is more demanding on the muscular system and requires a longer rest period. There is currently little research available suggesting the rest needed between subsequent trainig sessions of the same body part. This is due to a lack of a standard research procedure and accurate physiological marker indicating the point of maximum recovery.