Light loads also deliver muscle gains, suggests research

Research into weight training has revealed that heavy lifting is not necessarily to the key to muscle gains, with light loads delivering similar results.

It seems that lifting to near or absolute failure using light weights is just as effective as heavier weight lifting when if comes to muscle growth.

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Lighter loads

The main reason for this is that lifting to failure and doing so more often targets the type-I slow-twitch muscle fibres that physique-conscious individuals tend to neglect as they are considered central to improved endurance, rather than size.

However, in doing so it seems we’ve been short-changing our muscle-building potential. To this point, studies that focused on the hypertrophic capacity of type-I fibres were few and far between.

But ongoing research has uncovered truths about the growth rates of different muscle fibre types in response to various training intensities, which specifically shows that type-I fibres offer a reserve of untapped muscle-growth potential.

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Loaded for success

In a study published in the Journal of Applied Physiology, researchers from McMaster University in Hamilton, Canada looked at the effects of training to failure and determined that load had no effect on muscle growth (hypertrophy) or strength in experienced lifters.

During the 12-week study, participants performed three sets of nine to 12 reps to failure in four exercises, three times per week. One group lifted heavy weights (75-90% of 1RM), while the other used light loads (30-50% of 1RM).

By the end of the study both groups had substantially increased their strength and muscle mass, but there were no differences between groups, suggesting that training load had no effect on gains in lean muscle mass or strength.

Findings from another study support this stance. The study, published in the Journal of Strength and Conditioning Research, found that people who performed exercises using less than 60% of their 1RM to failure experienced muscle gains equivalent to those who lifting heavier weights over an eight-week period.

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Combined approach best

What we know is that type-I muscle fibres are maximally stimulated during longer duration sets that incorporate lower loads (less than 50% of 1RM) and that type-II fibers respond better to short sets where heavy weights (greater than 50% of 1RM) are used.

However, what this research suggests is that fibre-type specific hypertrophy – a combination of both approaches – will yield the best adaptive results when it comes to building the most muscle.

Lifting to near failure is the real key to inducing a muscle growth response, regardless of how much weight you use. Taking this evidence into account, it seems reasonable to conclude that differing training intensities can produce comparable degrees of hypertrophy across both muscle fibre types.

Accordingly, to maximise the response to training, it makes sense to work across the load continuum, using a range of reps but always aiming to work to near failure with each set.

Author: Pedro van Gaalen

When he’s not writing about sport or health and fitness, Pedro is probably out training for his next marathon or ultra-marathon. He’s worked as a fitness professional and as a marketing and comms expert. He now combines his passions in his role as managing editor at Fitness magazine.