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Yes
“Lifting heavy” is relative. Generally speaking, it’s a weight you can lift six to eight times with good form – roughly 80 per cent of your maximum output.
The people who stand to gain the most from lifting heavy weights are the least likely to do it. “For someone untrained or frail, the relative stimulus is enormous,” says Belinda Beck, professor of exercise science at Griffith University in South East Queensland. “Muscle nerve and bone tissue adapt quickly to meet that demand, producing far larger gains in strength and function than would ever be seen in someone already highly trained.”
By 80, most people who do not lift weights will have lost roughly 50 per cent of their strength
Maria Fiatarone Singh, University of Sydney
Adults who don’t engage in strength training stand to lose five to 10 per cent of their muscle mass per decade. “By the age of 80, most people who do not lift weights will have lost roughly 50 per cent of their strength,” says Maria Fiatarone Singh, professor of geriatric medicine and exercise science at the University of Sydney. This is “linked to frailty, falls, metabolic and cardiovascular disease, cognitive decline and earlier mortality”. She advises focusing on the glutes, quadriceps and triceps – the muscle groups that underpin standing, rising and climbing.
Other benefits include improved metabolism, increased insulin sensitivity and stronger bones. Beck points to a study of post-menopausal women with low bone mass who increased their spinal bone density by up to three per cent in less than a year from lifting weights as part of high-intensity training. (Experts consider even a two per cent increase significant). “Bone responds to mechanical strain,” says Beck. “That’s why heavier loading remains one of the few interventions shown to slow – or even reverse – age-related bone loss.”
Heavy lifting is often practised by endurance athletes to improve their performance rather than muscle size. Research conducted by Iñigo Mujika, an exercise physiologist and swimming and triathlon coach, shows that relatively heavy resistance training can improve sprint power and time-trial performance in cyclists by around two to eight per cent – without increasing body weight. The more powerful your muscles are, the less energy you need to maintain a specific speed. “Stronger muscles operate at a lower percentage of their maximum during repeated efforts,” explains Mujika. “The goal is not bigger muscles, but more efficient ones.”
No
An over-fixation on heavy weights can distract from the two most important drivers of health: consistency and effort. Heavier lifting produces more strain on the nervous system and connective tissues, meaning longer recovery times. This limits how often people can train productively.
There’s also evidence to suggest that, while the body can adapt to heavy weights up to a point, repeated high joint compression and spinal loading can push it towards cumulative micro-trauma – microscopic tears in muscle fibres and connective tissues – rather than resilience and strength.
The body doesn’t reward heroics. It rewards showing up
Stuart Phillips, McMaster University
“Fears about true powerlifting [weights from around 43kg for women and 53kg for men] are probably understated,” says Aaron Baggish, an exercise cardiologist at the University of Lausanne. “Exceptionally heavy lifting over many years may increase cardiovascular risk, particularly in people with established disease of the heart muscle, coronary arteries, valves or aorta.” On the other hand, concerns around more moderate forms of resistance training “are overstated”.
Stuart Phillips, a professor in kinesiology at McMaster University in Hamilton, Canada, advocates for “manageable loads”: weights that feel challenging but controllable. “You should be able to lift them with good technique, through a full range of motion, without grinding or straining,” he says. That means stable posture, controlled movement and stopping a set before your form breaks down. Beginners should seek advice from a qualified trainer to learn safe movement patterns.
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And the weights don’t have to be very heavy. Large clinical trials show that any regular muscle contraction – light or heavy – improves insulin sensitivity and glucose control, reducing the risk of type 2 diabetes. A 2023 study in the British Journal of Sports Medicine found that even relatively light loads – around 30 per cent of the heaviest weight someone could lift once – can build muscle if exercises are taken close to fatigue.
Phillips says that most benefits simply come from weight training that is repeatable: challenging enough to stimulate adaptation, light enough to recover from and done consistently. “The [body] doesn’t reward heroics,” he says. “It rewards showing up.”
