Gym junkies, here's why you could be wasting your time

Researcher
Dr Kathryn Mills
Writer
Sarah Maguire
Date
23 July 2019
Faculty
Faculty of Medicine and Health Sciences
Topic

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Muscle-strengthening exercises are vital for good health, but only up to a point, a Macquarie University review has revealed.

Three or more resistance workouts a week could be delivering no further benefits to your health than just two sessions, a Macquarie study has found.

All rounder: Benefits of the right amount of resistance exercise extend well beyond the musculoskeletal system.

“Often you have people saying, ‘I don’t want to go to the gym every day’. What our review showed is you don’t have to go every day,” says Dr Kathryn Mills, a lecturer in physiotherapy in the Department of Health Professions.

“If you just put in two resistance sessions a week – which is in line with both national and World Health Organisation (WHO) recommendations – that’s going to give you the maximum effect you’re going to get. Two sessions is optimal.”

Dr Mills is co-author of the study, Do the benefits of participation in sport and exercise outweigh the negatives? An academic review, for which the researchers scoured databases of English-language biomedical journals to source and review the available evidence.

It appears that many of these benefits are not realised if individuals are not working hard enough or if they participate too frequently.

When it came to resistance, or strengthening, exercise – which makes muscles work against a weight or force, such as dumbbells or your own body – the evidence showed that benefits extend beyond the musculoskeletal system to the cardiovascular, respiratory, metabolic, endocrine and immune systems.

“However, it appears that many of these benefits are not realised if individuals are not working hard enough or if they participate too frequently,” the study found.

Looking at cardiovascular health, the researchers reviewed large longitudinal studies involving several thousand people that demonstrated an association between strength training and a 23 per cent reduction in coronary heart disease in men.

Women who undertook moderate amounts of muscle strengthening exercise had low levels of risk factors such as cholesterol and triglycerides, and low rates of mortality.

However, women reporting more than 150 minutes of strength training per week did not have low mortality risks.

Similarly, when reviewing the effects of resistance training on the metabolic and endocrine system, the authors cited research that found that following the WHO guidelines reduced by 25 per cent the odds of having metabolic syndrome – a precursor for cardiovascular disease and type 2 diabetes – but that any more than one hour a week did not reduce the odds any further.

Weighing in: to get really good benefits, you need to be working at a minimum intensity of 60 per cent of the heaviest you can lift, push or pull, researchers say.

In adults over 70 years, regardless of their sex, a meta-analysis of 47 studies showed that two sessions per week consisting of two-to-three sets of 7 repetitions could improve muscle strength by up to 33 per cent.

Women need to work harder

Resistance exercise is essential for maintaining musculoskeletal health, particularly in post-menopausal women and the elderly.

But another surprising find from the review, says Mills, is that women don’t push themselves hard enough to get the maximum benefits for the musculoskeletal system.

“Women often don’t derive the same benefits from resistance exercise as men do, and that seems to be because women don’t work as hard,” Mills says.

“To get really good benefits, you need to be working at a minimum intensity of 60 per cent of what you could maximally lift, push or pull, and up to 80 per cent,  and most women report working ‘somewhat hard’, not ‘hard’.

Women don’t push themselves hard enough to get the maximum benefits for the musculoskeletal system.

“So even though they are undertaking these activities they might not be working at the right intensity to reap the potential musculo-skeletal benefits.”

However, there are cardiovascular and respiratory benefits in doing the exercises ‘somewhat hard’ because it can lower your blood pressure, Mills says.

“Traditionally, people with high blood pressure have been told not to lift weights because it does cause an immediate spike in blood pressure, but over the long term it has a reducing effect.

“But if you want all the benefits, you do have to be working ‘hard’.”

Supervision and technique combat the harms

The study concluded that the benefits far outweigh potential harms of strength training, which comes with a small risk of musculoskeletal injuries, particularly in the lower back.

“The biggest thing that will cause injury from a strengthening program is not technically doing it right, so to have someone properly show you how to do it is important,” Mills says.

“Than can be a physiotherapist, an exercise physiologist, or a personal trainer at the gym – there are lots of different professions in Australia that will show you how to do an exercise appropriately.”

Dr Kathryn Mills is a Lecturer of Physiotherapy in Macquarie's Department of Health Professions.

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