Over the past several decades, exercise science researchers have discovered three basic mechanisms for growing muscle: 1) mechanical tension, 2) muscle damage and 3) metabolic stress (Schoenfeld, 2010). The type of program for increasing muscle mass is called hypertrophy training, which is based on techniques used by bodybuilders to perfect their physiques. Fortunately, you don’t have to be a bodybuilder to benefit from these evidence-based techniques. The following list provides tips for exactly what to do, and what not to do, when it comes to building muscle.
Do: Contract your muscles against resistance and create some damage.
Don’t: Lift light weights.
Whether you choose to do challenging bodyweight exercises such as push-ups and pull-ups, or traditional weight-lifting moves like bench presses and lat pull-downs, you are contracting muscles against a resistive load, thereby creating mechanical tension. Mechanical tension is the amount of tension developed by muscle fibers in response to a stimulus, and in this case the stimulus is resistance exercise. Researchers believe that this type of tension slightly damages the muscle tissue, causing a growth response. Further, eccentric movements, like the lowering part of an exercise, cause the most damage and are necessary for optimum muscle growth. Lastly, be sure to lift progressively heavier weight loads and/or perform harder bodyweight exercises as you become stronger. Performing endless repetitions with a light weight does not promote muscle growth.
Do: Create metabolic muscle stress by choosing the right duration for your sets.
Don’t: Perform the repetitions too quickly.
First, you must create mechanical tension within the muscles as described above, then you must keep the muscles exposed to that tension long enough for a buildup of various metabolites (e.g., lactate, hydrogen ion, inorganic phosphate and creatine) to occur. This process creates a metabolic stress in muscle tissue that triggers hypertrophic growth. Practically speaking, muscles must experience a load that they are unaccustomed to and they must experience that load for a certain duration (known as “time under tension”). That is, muscle fibers that are engaged between 30 to 90 seconds of time under tension per set tend to respond by increasing in thickness. For example, an effective repetition strategy is to perform the concentric action, or the upward movement, at fast or moderate speeds (1 to 3 seconds) and perform the eccentric action at slower speeds (2 to 4 seconds). So, a set of 10 repetitions performed at a concentric speed of 2 seconds and an eccentric speed of 4 seconds takes about 60 seconds to complete. Lastly, when it comes to building muscle, the number of sets matters. While there are benefits to performing just one set of an exercise such as improved strength and muscular fitness, multiple set routines (between four to six sets) are required for optimum hypertrophy.
Do: Choose the right rest interval between sets.
Don’t: Wait too long between sets.
Resting about 60 seconds between sets appears to be the best option for muscle hypertrophy. Waiting much longer than a minute to perform your next set compromises the metabolic-stress aspect of training, while resting for less than 60 seconds doesn’t allow enough recuperation for the muscle to perform well in the subsequent set.
Do: Plan your rest days appropriately.
Don’t: Work the same muscle groups too often.
Allowing muscles to rest and regenerate between challenging workouts will keep your muscle-building goals on track and help prevent overuse injuries due to overtraining. Bodybuilders have figured out how to work around this important principle by performing split routines. These allow them to train most days of the week by focusing on specific muscles each day. An example of a split routine is to work the chest, shoulders and triceps on Monday, followed by legs on Wednesday, and finish with back and biceps on Friday. Evidence supports the practice of waiting 72 hours before training the same muscle group again to allow for adequate muscle repair, especially for exercisers who employ multi-set training.
Putting It All Together
To provoke muscle hypertrophy, use the approaches above for planning your next workout. In summary, the variables of time under tension and load (weight) are manipulated through exercise program designs that call for six to 12 repetitions (which typically take between 30 to 90 seconds to complete) for four to six sets at a weight that causes muscle fatigue by the end of each set. Plan on performing resistance exercises for each muscle group once or twice a week for several months to allow the body to adapt to this increased volume of targeted exercise before expecting any appreciable gains in hypertrophy. Also, pay attention to muscle soreness after your workouts and postpone training the area again until the soreness has subsided. You definitely want to allow adequate rest between multi-set workouts so the soft tissues and the joints have time to recover and resist injury.
Schoenfeld, B.J. (2010). The mechanisms of muscle hypertrophy and their application to resistance training. Journal of Strength & Conditioning Research 2010, 24, 10, 2857–72. doi: 10.1519/JSC.0b013e3181e840f3. Review.