I often hear people talk about how lifting lighter weights is for toning your body and not to get bigger.  That lifting lighter weights will help develop endurance rather than muscle mass.  There’s some truth to that but can you actually build considerate muscle by lifting lighter weights as oppose to heavy weights?  Technically yes, and here’s why.

Building muscle is about progressive resistance where you gradually add more weight to increase the intensity.  By adding more resistance/intensity, you force your body to make muscular changes in order to adapt to the stresses of the exercise.  Does lifting heavy weights influence change and adaptation, yes, but there’s not much of a relationship between muscle strength and muscle size.  <– This is very important to understand.

In fact, you see a lot of competitive strongman and olympic weight lifters who are incredibly strong but may not look physically impressive, at least not like a bodybuilder.  This is because muscle size is not necessarily dependent on lifting heavy weights.

Much of the modern bodybuilding techniques involve training to failure and lifting with moderate weights as oppose to lifting very heavy weight.  You see bodybuilders training with this style where they training with rep ranges of 20-30 reps per set.  These are giant sets and training this way will tax your muscles and demand adaptation and/or growth.

Lifting heavy is primarily a strength building technique which promotes more of a neurological response or muscle memory type training where your body gets better at doing that exercise at that weight intensity.  This is an important concept to understand because strength is dependent on lifting heavy weights.  The body adapts to the demands that you put it through.  During heavy sets, you may engage different body parts that work synergistically to complete the movement.  There’s nothing wrong with training this way if your goal is to get stronger, which many people want to do.  The problem is that it’s not the best way to build muscle for a particular body part in isolation.

Muscles work in an economical way.  There’s two types of muscle fibers and we normally use type I fibers (slow twitch fibers) whenever we lift at first.  After the muscles are fatigued, we begin to tape into the type II fibers (fast twitch) muscles that will make your muscles grow by promoting hypertrophy.

According to a study I recently read, lifting light weights to failure does produce muscle building results.  This study was performed with younger adults (early 20s), where there was one group of young men that trained with minimal resistance but trained to failure for a few weeks.  There was another group that began to train at the same time but they used a different technique where they workout with heavy resistance (about 70% 1MR), but not to failure.  The study found that after several weeks of training, both groups had developed the similar amounts of muscular growth within the allotted time frame.  This should be eye opening because for many decades it’s been common knowledge that you need heavy resistance to gain muscle.

Keep in mind that although muscle size increases were about the same, there was a notable difference in strength gained.  Strength is very relevant to weight resistance so the first group in the study who trained with lighter weights to failure was not as strong as the group who trained with heavy weights.  This can be a good side affect to training with heavier weights if that’s an important part of your goal.  However, you should also note that with lifting heavier weights, you’ll also get some side affects like joint degradation and an increased risk of injury.

How do you know what weight is appropriate?

You’ll need to go through a trial and error period, where you need to find your weight sweet spot that will force your muscles to fatigue properly.  Once you find this weight range, you’ll make some good gains and you’ll start to grow.  It’s likely that you’ll have to go through this process several times if you don’t want to plateau an as your muscles get better at lifting that particular weight range.  So my suggestion is that if you can do that exercise with that weight intensity and can go past the 20-30 rep range per set, then you need to either increase the number of sets per exercise or progressively increase weight but obviously a moderate increase and nothing thats too heavy than what you were previously lifting.

So here’s my take.

If your goal is to build muscle and to build it safely and effectively, I highly recommend lowering the weight that you use at the gym.  Get into a training routine where you focus on perfect form and learn to train to failure with lighter weights.  Just make sure that you always get to muscular failure or else you won’t tax your muscles and may not see any muscle growth.  I can’t stress that enough because most people don’t train to failure and therefore the muscle will never grow because your not tapping into the type II muscle fibers.

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Miguel Quintana
A passionate fitness trainer who enjoys living and promoting a healthy fitness lifestyle. He is known for developing effective training programs and uses science proven methods with all his clients.