People who engage in resistance training to achieve muscle hypertrophy or increased muscle strength are often faced with the question whether to use heavy weights or light weights for their exercises.
The decision to use either heavy weights or light weights depends on the specific goals you set out to achieve. People can engage in resistance training to achieve increased muscle size, strength, power, speed, better muscle endurance, improve balance, coordination, and flexibility, reduce body fat, improve their general health (e.g., lower blood pressure, strengthen connective tissue, reduce stress), and as rehab therapy for injuries. Athletes may be interested in developing muscle strength in specific muscle groups to maximize their performance, whereas those participating in bodybuilding may be more concerned about the esthetic development of their body.
Regarding the development of strength, studies have shown that maximum results are achieved with the use of heavy weights. But what may be considered heavy by one person may be considered light by another. So, how do we know what weight is heavy and what weight is light for our level of training? To determine whether a particular weight is light, moderate, or heavy, we first need to establish what our 1RM is. 1RM stands for one repetition maximum. The 1RM is the maximum weight we can lift one time using a particular group of muscles. Once we know what that weight is, we can use that value to determine the category of weight we are lifting. Weights greater than 80% of the 1RM for a muscle group can be considered heavy weights. 60% -80% of the 1RM can be considered a moderate weight, whereas anything below 60% can be considered light weights. Developing maximum strength in a muscle group, therefore, requires the use of weights 80% 1RM or greater.
Achieving maximum muscle hypertrophy, however, is a somewhat more forgiving process, and s studies have shown that resistance exercises with weights as low as 30% 1RM can produce muscle hypertrophy. The only factor that seemed to affect the degree of muscle hypertrophy achieved was that the resistance exercise should be performed to the point of muscle failure. There was no difference in the amount of muscular hypertrophy achieved between using weights of 30% 1RM and using weights of 80% 1RM, as long as the exercise was performed to the point of muscle failure.
There is, however, one important caveat, in that 20% 1RM appeared to be too light a weight to stimulate muscle growth and hypertrophy. On the other hand, using weights that are too heavy leads to a greater frequency of injury, decreases the volume of training attainable, and thus can retard the development of muscle hypertrophy. As with any other sport, a coach can provide tremendous benefit by prescribing a regimen that meets your specific needs, ensuring adequate rest in between sessions, and teaching the right technique to prevent injuries. Even before you embark on a resistance training journey, you should get a physical examination done to determine if it is safe for you to engage in resistance training. Resistance training has enormous benefits for our health, so depending on your specific goals and needs, you should follow these guidelines to determine the optimal weight to achieve the goals you set.