Should You Lift Light or Heavy? Science Says Both Work

Researchers from McMaster University reviewed over 190 studies and concluded that the most crucial factor in gaining strength and muscle is consistently performing resistance training, regardless of the specific details like weight amount or frequency. Their findings stress that while certain methods may optimize strength or muscle size, any form of weightlifting is effective in achieving overall gains.

Regardless of using light or heavy weights, consistently lifting to your limit enhances muscle and strength. The specifics of your regimen are secondary to establishing a consistent routine, researchers have determined.

Research conducted by kinesiologists at McMaster University, focusing on key factors in resistance training—such as the amount of weight lifted, frequency, and repetitions—has concluded that all types of resistance training yield positive results. This includes body-weight exercises like planks, lunges, and push-ups.

“There are a dizzying number of factors and combinations to consider when creating a weightlifting program to maximize strength and muscle growth,” says Stuart Phillips, a Kinesiology professor who conducted the work with graduate students Bradley Currier and Jonathan Mcleod.

“This is an age-old debate among athletes and strength and conditioning coaches: what combination leads to the best gains?”

For the study, published today in the British Journal of Sports Medicine, researchers reviewed 192 randomized, controlled studies with a total sample size of more than 5,000 people evenly split between women and men, making it the single largest project of its kind.

The work is the culmination of years of planning, collecting, and analyzing massive amounts of data revolving around three key resistance-training variables: higher versus lower loads, single versus multiple sets, and training frequency: whether one, two or three (or more) sessions per week.

Kinesiologists at McMaster University found that all forms of resistance training programs are beneficial – regardless of how much you lift, how often, and how many times. Credit: Matt Clarke/McMaster University

Most fitness experts have come to believe that using the heaviest weights – which can only be lifted three to five times – works best for building strength while using weights that can be lifted eight to 10 times works best for building muscle size.

Based on their original research, McMaster researchers have spent the last decade or more pushing back against the idea that heavier weights are the only option.

Phillips and his team have published several papers showing significant gains are possible when lifting lighter weights toward the point of exhaustion. That can mean 20 to 30 repetitions, sometimes more.

In this comprehensive review of research from across their field, the researchers found that to maximize muscle strength, lifting heavier weights is most effective, while to maximize muscle size, one should do each exercise several times and the weight lifted is less important.

“Our analysis shows that every resistance training prescription resulted in strength and muscle mass gains. Complex prescriptions are sufficient but unnecessary to gain strength and muscle. Simple programs are extremely effective, and the most important result is that people can benefit from any weightlifting program,” says Currier. “Seek guidance if you are unsure where to begin and how to progress, but it doesn’t need to be complicated.”

Researchers say the analysis is good news for anyone, regardless of age, interested in gaining strength and maintaining more muscle, which is important to preventing injury, maximizing mobility, and optimizing metabolism.

“The biggest variable to master is compliance,” said Mcleod, “Once you’ve got that down, then you can worry about all of the other subtle nuances, but our analysis clearly shows that many ostensibly important variables just aren’t that essential for the vast majority of people.”

Reference: “Resistance training prescription for muscle strength and hypertrophy in healthy adults: a systematic review and Bayesian network meta-analysis ” by Brad S Currier, Jonathan C Mcleod, Laura Banfield, Joseph Beyene, Nicky J Welton, Alysha C D’Souza, Joshua A J Keogh, Lydia Lin, Giulia Coletta, Antony Yang, Lauren Colenso-Semple, Kyle J Lau, Alexandria Verboom and Stuart M Phillips, 6 July 2023, British Journal of Sports Medicine.
DOI: 10.1136/bjsports-2023-106807