Any person that just starts getting into lifting will eventually ask themselves this question: should I lift light or heavy? The old myth is that lifting heavy grows muscles bigger, while lifting light makes muscles more toned. This idea has been debunked numerous times — according to a study funded by the Natural Sciences and Engineering Research Council of Canada, a group of men who lifted heavy (70-90% of 1 rep max) and a group who lifted light (30-50% of 1 rep max), ultimately had very similar muscle growth. In most scenarios, lifting light and heavy weight isn’t what makes the difference, but instead reaching a state of muscle fatigue that can induce hypertrophy.
Often, choosing between heavy and light weight will depend on what your priorities are when it comes to lifting. For beginner lifters, using light weight to develop the proper form for certain exercises is often an important first step in starting a lifting regimine. Learning how to properly handle the weight is crucial, because it will reduce the chance of injury in the long run. However, light weights aren’t just for the beginner lifter. Lifting lighter weight, but for more reps, activates the slow-twitch fibers in your muscles, burning more calories and fat throughout the workout. Greater number of reps increases the time under tension of your muscle, allowing for increased muscle endurance. When workouts become longer, and you are doing a greater number of lifts, this muscle endurance that you’ve developed will become ever more beneficial. Lastly, using lighter weights to do an exercise to failure at the end of your workout can induce an amazing pump.
However, heavy weights have their benefits as well. When lifting, your goal should always be to fatigue your muscles, and heavy weights naturally will allow you to get fatigued more quickly. With less reps per set, heavy weight will develop your fast-twitch fibers; this development will allow you to better your explosiveness and the anaerobic aspect of the lift. If you consistently lift the same amount of weight every workout, your body will soon get used to it, and it will not see growth as fast as it previously did. At this point, you need to induce hypertrophy. There are many ways of achieving hypertrophy, one of which is lifting heavier and heavier weight every workout, but for a similar number of reps. Training the body to handle greater and great weight is a perfect way to achieve your strength goals when lifting.
For most people, however, having a mixture of heavy weight sets and light weight sets can give them the best from both worlds. For instance, starting your workout with some intense 5 by 5 compound lifts, and finishing it off with a burnout 3 by 20 is a great way to become a well rounded lifter. At the end of the day, lifting light and lifting heavy is just a matter of where your priorities lie.