On your first time at the gym, you’ll typically see a big difference in the weights used by men and the ones used by women. Some women will use 2.5kg weights for many reps in an effort to tone up, and the men will typically push for higher weight for a few reps in an effort to gain muscle and strength.
The idea is that high reps help you lose fat and make muscles more toned, while raising endurance. On the other hand, low reps with higher weights help build muscle and increase strength.
Is that it though? High reps for fat loss, low reps for strength and muscle building?
Not really - there’s a lot more that comes into play. For example you can lose weight, build muscle and increase strength with just about any rep range, but in terms of time-efficiency, safety or overall effectiveness then the ideal rep range seems to be between 6 and 12 reps.
High Reps vs. Low Reps For Strength
There's a popular recommendation in terms of reps for a specific goal or outcome that are based on a percentage of your 1RM (1 Rep Max). Your 1 Rep Max is the weight that you can, but only barely lift for one rep. Your maximum lift. So if you can lift 20kg at your max, then 50% would be 10kg. If your max is 10kg, 50% would be 5kg and so on. These Recommendations are:
For Strength: 1-5 reps at 80% to 90% 1RM
For Hypertrophy: 6-12 reps at 60% to 80% 1RM
For Endurance: 15+ at 40% 1RM
“Hypertrophy” typically means muscle building, which isn’t fully accurate, as we’ll explain. Muscles are made of two types of fibers, Type 1 and Type 2. Type 1 fibers are called Slow Twitch Fibers. These are endurance based fibers and are slow to fatigue and are built with higher reps. Lower reps on the other hand, build Type 2 fibers, or Fast Twitch Fibers. These fibers have greater power but fatigue quickly.
So the juries in and they support low reps with heavy weight for optimal strength increases, however, high reps do still elicit gains in strength as well. For example, a study of 23 cyclists were placed into high resistance/low repetition, low resistance/high repetition, or cycling only groups for a 10 week program. The first group adapted to the resistance, gaining strength just as we’d expect but interestingly, muscle hypertrophy and the overall endurance was equal among the high resistance and low resistance groups. So if you’re looking to build muscles regardless of strength, then high reps is still open to you!
As this study and many others highlight, for optimal strength gains, lift relatively heavier weight for low reps. This is in line with how Powerlifters train for competitions to help increase neuromuscular adaptation, which is the efficiency of the brain to control the muscles. You can get stronger as a result of increase in muscle size OR increase in neuromuscular adaptation.
High Reps vs. Low Reps For Fat Loss
Okay so, heavy weights are for building muscle. But what about fat loss? Can lifting heavier weights help you burn more fat too?
A study from Birmingham’s University of Alabama showed that dieters lifting heavy weights lost the same amount of weight as dieters that were just doing cardio, but all the weight from the weightlifters was fat, whereas the cardio subjects lost muscle and fat.
The common belief is that magically, high reps get rid of fat better than low reps with high weight, but the evidence isn’t really there yet. It just concludes that lifting weights is good for weight loss and what we can take from this, is that it’s not just lifting heavy, or lifting a lot… it’s lifting to failure. It’s giving your max that results in weight loss, whether that’s 5x30 reps of 10kg or it’s 5x8 of 45kg.
If you’re looking to lose weight, we suggest you do some weight lifting to the point of failure, focus on your core for the most part and don’t neglect your back! Have a day of cardio in your routine and cut out the junk food and carbs - you’ll soon see weight loss!