Training

Heavy weights or light weights for muscle?

You don't need to lift heavy to grow, but heavy lifting builds strength best. Here's how rep ranges actually work.

By Logpulse. Published 11 October 2026. 2 minute read.

“Lift heavy for size, light for tone” is one of the longest running myths in the gym. There’s no such thing as toning. There’s building muscle and losing fat. And it turns out the weight on the bar matters less than you’d think.

What the research found

A 2017 meta-analysis compared training with low loads (under about 60 percent of your one rep max, which usually means more than 15 reps) and high loads (above 60 percent). When sets were taken close to failure, muscle growth was similar. Heavy loads produced greater gains in maximal strength, as you’d expect, because strength is partly a skill of lifting heavy.

So both work for size. What makes light weights work is effort. A set of 25 that ends 10 reps short of failure does little. A set of 25 that ends one or two reps short of failure is very effective.

The catch with very light and very heavy

  • Very light, very high reps (30 plus) are effective but painful and slow. The burning and breathlessness often stop you before your muscles are truly challenged.
  • Very heavy, very low reps (1 to 3) build strength but need more sets for the same growth, and they’re harder on joints and recovery.

A practical approach

Most of your training in the 6 to 15 rep range covers both strength and size with manageable fatigue:

  • Compound lifts like squats, deadlifts, bench, rows, presses and pulldowns: 6 to 10 reps
  • Small muscles and isolation like curls, lateral raises and calf raises: 10 to 15 reps

That’s how the Logpulse program sets its rep ranges.

At home with light equipment?

Good news: dumbbells, bands and body weight are enough to build muscle if you push sets hard. Slow the lowering phase, pause at the hardest point, and add reps until you’re close to failure. The Logpulse program and workout builder have home versions of every move.

This is general information drawn from published research, not personal medical or dietary advice. If you have a health condition, are pregnant, or have a history of disordered eating, speak to your GP or an Accredited Practising Dietitian first. For support with eating concerns, the Butterfly Foundation helpline is 1800 33 4673.

Sources

  1. Schoenfeld BJ, Grgic J, Ogborn D, Krieger JW. Strength and hypertrophy adaptations between low vs high load resistance training: a systematic review and meta-analysis. Journal of Strength and Conditioning Research. 2017;31(12):3508 to 3523.
  2. Lasevicius T, Ugrinowitsch C, Schoenfeld BJ, et al. Effects of different intensities of resistance training with equated volume load on muscle strength and hypertrophy. European Journal of Sport Science. 2018;18(6):772 to 780.

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