Studies show you can hypertrophy muscles by lifting heavy weights or lighter weights. However, if you lift lighter, you’ll need to do enough repetitions to thoroughly fatigue the muscles. If you’re trying to build strength, lifting at a high percentage of your one-rep max maximizes strength gains. However, you don’t have to lift at a high percentage of your one-rep max to gain muscle, as long as you fatigue your muscles and do a high enough volume.
Some people prefer using lighter weights of around 50 to 60% of their one-rep max and working muscle to fatigue. Some studies even suggest that working with lighter weights, as long as you fatigue the muscles you’re working, is more effective for hypertrophy gains since training volume contributes to hypertrophy gains.
However, there are reasons to work with heavier weights, at least sometimes. A study shows that working with heavier weights may make your body more efficient when they work against resistance.
Higher Resistance for Better Muscle Efficiency
Most studies show you can develop muscle and make strength gains using lighter weights, as long as you do enough repetitions to exhaust the muscles you’re working. In the study, researchers asked 26 healthy men to work their muscles using a leg extension machine for six weeks. On the leg extension machine, one group of lifters pushed against 80% of their one-rep max, while the other worked at 30% of their one-rep max. Both groups did the exercise to failure three times per week.
The results? At the end of the 6- week study, both groups had gained similar amounts of muscle. However, the group who lifted heavier improved their one-rep max more than the group who lifted lighter. That translates into greater strength!
Why did the heavy lifters increase their one-rep max, a measure of strength, more? The researchers used electrical current to determine how much of the available muscle force the lifters could tap into when they did leg extensions. They found the heavy lifters could tap into more of their muscle’s force capacity relative to those who worked against lighter resistance. The reason? The guys who worked against heavier resistance had better conditioned their nervous systems to maximize force output. Remember, strength gains don’t just come from increasing muscle size or the number of contractile elements within muscle fibers; it also comes from training the nervous system to interact with the muscles more efficiently.
What does this mean in practical terms? When you work with heavier weights, muscle efficiency improves, and it doesn’t take as much effort to generate the same amount of force. So, if you routinely work with heavy weights and take a break from training for a few weeks, when you come back, it’ll be easier to get back into working with the weights you did before than if you trained with lighter weights. Your muscles are more efficient, and your nervous system is better primed to lift heavy.
More Reasons to Lift Heavier
Although it’s clear you can build muscle size by lifting lighter weights, lifting at a higher percentage of your one-rep max is the way to maximize strength gains. When you lift heavy, you activate fast-twitch muscle fibers, those optimized for strength and power right away, and fatigue them. This forces them to adapt and become stronger. The formula for maximal strength gains is to lift at 80% to 90% of one-rep max and complete 3 of 4 sets of 2 to 5 repetitions. If hypertrophy is your primary goal, going a bit lighter, 60 to 80% of one-rep max and 6 to 12 repetitions works well.
Another advantage of lifting heavier is you can reduce the time you spend training. It takes time to do enough repetitions to fatigue your muscles when you use lighter weights. If you want to build strength in the most expedient way possible, go heavier on the weights. Of course, you shouldn’t max out on the weight every time you lift, but heavier sets should make up some of your training.
Lifting Heavier is Better for Bone Health
According to Harvard Health, we lose bone mass at a rate of around 1% per year after the age of 40. As bones become weaker and more fragile, the risk of hip fractures goes up. You often hear how it’s important to get enough calcium and vitamin D to reduce bone loss, but you also need to wake up cells called osteoblasts that produce new bone. High-impact exercise helps do this, but so does strength training. But you’ll get the most bone health benefits from strength training if you lift heavy. Lighter weights are not as effective at preventing bone loss; intensity matters! Some studies even suggest that you can build new bone even later in life if you lift heavy weights.
You Can Build Strength While Limiting Hypertrophy
If you’d like to build strength without boosting muscle size, lifting at a high percentage of your one-rep max will help you do that. You won’t see major hypertrophy gains if you use high resistance and low reps since you need greater volume (more repetitions and more reps) to maximize hypertrophy. Look at the difference in physiques of bodybuilders and powerlifters. Powerlifters are uber-strong, but they don’t always have well-developed muscles. In contrast, bodybuilders who use moderate resistance and do more repetitions than the powerlifters have defined musculature but won’t always be impressively strong. They train differently, for aesthetics and muscle development, by using moderate resistance and moderate repetitions.
The Bottom Line
Now you know how lifting heavy works in your favor, especially if you’re trying to build strength. Listen to your body though and don’t push harder than your body is ready for. Working with heavier weights carries a higher risk of injury. Gradually work up to heavier weights and give your muscles at least a 48-hour break after working against a challenging resistance.
- Physiol., 29 May 2017 | https://doi.org/10.3389/fphys.2017.00331.
- Harvard Health Publishing. “Strength training builds more than muscles”
- com. “7 Reasons Why I Lift Heavy (And You Should Too)”
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