There has long existed debate about what type of exercise is most beneficial to an individual - strength or endurance?
Until recently, most studies conducted on the benefits of exercise have focused on benefits of endurance and aerobic exercise, lacking data on strength-based exercise.
While aerobic exercise and improved cardiorespiratory fitness is absolutely an important aspect of overall health, evidence suggests that the addition of anaerobic, strength-promoting exercise can provide further benefits to human health and longevity than aerobic alone.
What did the study find?
A recent study conducted by the University of Sydney examined associations between strength-promoting exercise (SPE) and all-cause, cancer and cardiovascular disease mortality. The researchers pooled data from over 80,000 adults aged over 30 years and found that, following exclusions for prevalent disease/ events in the first 24 months, participation in any SPE was favourably associated with all cause and cancer mortality.
Specifically, SPE was linked to a 23% reduction in all-cause mortality and a 31% reduction in cancer mortality, with a higher volume of SPE modestly associated with a greater reduction in all-cause mortality. In addition to this, combining SPE and aerobic exercise was associated with a greater risk reduction in mortality than aerobic physical activity alone.
The authors attributed this relationship to the primary adaptation from SPE - increased muscle strength - which has previously been associated with reduced cancer mortality independent of aerobic fitness.
How does strength-promoting exercise produce these effects?
Exercise encourages adaptation within the body. Targeting different systems during exercise can trigger various adaptations of different kinds and herein lies the key to understanding the benefits of exercise.
It is well known that load-bearing exercise leads to greater bone mineral density. After load-bearing exercise, the primary adaptation to the heavy weight is to build a stronger support structure in the muscles and the bones.
A key point to remember is that adaptation and healing are two separate processes within the body. Gentle and regular muscle strengthening is key to encourage the body to adapt and better handle the same action next time.
Pushing the body to the point where it must focus on healing does not produce the optimal adaptive benefits. As muscle protein synthesis (a marker of adaptation) peaks at roughly 24 post exercise, if it takes longer than 1 day to recover from a workout, adaptation is less likely to occur.
What else can strength-promoting exercise do for my patients?
The following associations have been made with SPE are a result of the higher muscle strength it promotes via adaptation:
- Reduced all-cause mortality in adults who meet guidelines of 2 sessions per week.
- Reduced risk of fatal and non-fatal myocardial infarction.
- Reduced all-cause mortality in cancer survivors, independent of aerobic fitness.
- Inverse relationships with age-related weight gain and metabolic syndrome.
- Improvements to glucose metabolism via improved glucose uptake and insulin signalling in skeletal muscle.[5,6]
- Improving body fat percentage and resting metabolic rate via maintaining lean muscle mass.
- Reduced inflammatory markers such as C-reactive protein and tumour necrosis factor-alpha.
- Improved long-term cognition and white matter volume in older women.
- Reduced depressive symptoms and happier moods.
- For children and adolescents, SPE has been shown to benefit strength, athletic performance, balance, bone density, lipid profiles and self-esteem.
Why is this important?
The shift towards a sedentary lifestyle is well-known and documented. The amount of time spent in sedentary behaviour has greatly increased over time, from 34% of time spent sitting or lying 2005 to 41% in 2012, and this trend is expected to continue.
Roughly 15% of Australian adults meet the recommended level of combined aerobic and strength-based exercise as recommended by the Department of Health (2 sessions of muscle strengthening exercises and 150-100 minutes of moderate intensity physical activity each week), while 50% meet the aerobic activity recommended. This may be due to the perception of strength-training as a gym-based activity, which may come with barriers to participation.
Not only are Australians missing out physical activity targets, the problem is compounded by sitting or lying still for a longer portion of time - at work, at home, on transport and in social activities - and increasing the risk of the negative consequences associated with sedentary behaviour.
How can we encourage this with our patients?
Aside from detailing the positive benefits that SPE can offer, practitioners can focus on the ease of which SPE can be incorporated into someone's lifestyle. Indeed, one of the key takeaways from the Sydney University paper was that the benefits of body-weight exercises were comparable to those conducted within a gym or clinical setting.
Examples of strength-promoting and resistance exercise:
- Body-weight exercises (e.g. push-ups, squats, lunges)
- Using weights or household items as weights (e.g. soup cans, books)
- Using weight equipment at a gym (e.g. barbells, leg curl machine)
- Using resistance bands (e.g. in a pilates class)
- Stamatakis E, Lee IM, Bennie J, et al. Does strength promoting exercise confer unique health benefits? A pooled analysis of eleven population cohorts with all-cause, cancer, and cardiovascular mortality endpoints. AM J Epifemiol 2017 [Abstract]
- Ishikawa S, Kim Y, Kang M, et al. Effects of weight-bearing exercise on bone health in girls: a meta-analysis. Sports Med 2013;43(9):875-892 [Abstract]
- Atherton PJ, Smith K. Muscle protein synthesis in response to nutrition and exercise. J Physiol 2012;590(Pt 5):1049-1057 [Full Text]
- Artero EG, Duck-chul L, Lavie CJ, et al. Effects of muscular strength on cardiovascular risk factors and prognosis. J Cardiopulm Rehabil Prev 2012;32(6):351-358 [Full Text]
- McPherron AC, Guo T, Bond ND, et al. Increasing muscle mass to improve metabolism. Adipocyte 2013;2(2):92-98 [Full Text]
- Holten MK, Zacho M, Gaster M, et al. Strength training increases insulin-mediated glucose uptake, GLUT4 content, and insulin signalling in skeletal muscle in patients with type 2 diabetes. Diabetes 2004;53(2):294-305 [Full Text]
- Westcott WL. Resistance training is medicine: effects of strength training on health. Curr Sports Med Rep 2012;11(4):209-216 [Abstract]
- Ogawa K, Sanada K, Machia S, et al. Resistance exercise training-induced muscle hypertrophy was associated with reduction of inflammatory markers in elderly women. Mediators Inflamm 2010;2010:171023 [Full Text]
- Best JR, Chio BK, Liang Hsu C, et al. Long-term effects of resistance exercise training on cognition and brain volume in older women: results from a randomized controlled trial. J Int Neuropsychol Soc 2015;21(10):745-756 [Abstract]
- Craft LL, Perna FM. The benefits of exercise for the clinically depressed. Prim Care Companion J Clin Psychiatry 2004;6(3):104-111 [Full Text]
- Dahab KS, McCambridge TM. Strength training in children and adolescents: raising the bar for young athletes? Sports Health 2009;1(3):223-226 [Full Text]
- Australian Bureau of Statistics. Perspectives on sport in Australian idle: physical activity and sedentary behaviour of adult Australians. Released 25th November 2013. [Source]
- Bennie JA, Pedisic Z, van Uffelen JG, et al. The descriptive epidemiology of total physical activity, muscle-strengthening exercises and sedentary behaviour among Australian adults - results from the National Nutrition and Physical Activity Survey. BMC Public Health 2016;16(73):1-13 [Full Text]