Is this exercise all it’s cracked up to be? Here’s what the research says

Naveed Saleh, MD, MS | November 03, 2021

Readers of a certain age may remember the infamous Saturday Night Live characters Hans and Franz, and their promise to “pump you up.” In the intervening decades, it appears that their raison d'être seems to have been lost on the American public.

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Woman doing pushups on yoga mat

A majority of Americans do not perform resistance training exercises even though current studies tout its benefits to health.

Results from a population-based study, published in the American Journal of Preventive Medicine (AJPM), indicated that three of five US adults do not perform any muscle-strengthening exercises, a form of conditioning that is related to better health. Factors underlying this association include older age, insufficient aerobic activity, lower income, decreased educational attainment, worse self-rated health, being female, and being overweight/obese.

Here’s a closer look at the benefits of resistance training as it relates to certain age groups and conditions, based on current research.  

Children with disabilities

Parents often worry that resistance training is bad for their children. A common myth is that the forces elicited by resistance training can do damage to immature skeletons, and induced loading can result in growth-plate injuries. Fortunately, no evidence supports such claims, and resistance training has not been demonstrated to affect either adult height or segment length in children routinely exposed to high forces, such as elite gymnasts, according to the authors of a narrative review published in the American Journal of Lifestyle Medicine.

Resistance training is just as important for young children with disabilities, the authors wrote. Even though results from sufficiently powered randomized controlled trials are few, many small studies indicate the various positive effects of resistance training in children with physical or mental disabilities. Resistance training is linked to mental and physical health benefits via improving muscle strength, body composition, self-concept/functionality, decreasing pain or injury risk, and strengthening bone/tendons. 

When compared with other interventions, resistance training lacks adverse effects. Of note, the authors highlighted the effects of resistance training with regard to various types of disability such as Charcot-cerebral palsy, Down syndrome, Ehlers-Danlos syndrome, juvenile idiopathic arthritis, obesity, and spina bifida.

Muscle strength

The age-associated loss of muscle strength is called dynapenia, and it increases the risk of mobility limitations and death in older people. It is estimated that only 8.7% of adults aged 75 years or older perform resistance-training exercises.

In a systematic review and meta-analysis published in Sports Medicine, researchers found that resistance training boosted muscle strength in what they called "very elderly" (ie, 75 years or older). It also benefited the "oldest-old" (ie, aged 80 years or more). Muscle hypertrophy occurred at the whole-muscle level in the very elderly. The effect size on strength was large and on whole-muscle-hypertrophy was small.

“We found that very elderly adults can increase their muscle strength and size by participating in resistance-training programs,” wrote the authors. “These effects were observed with resistance training interventions that generally included low weekly training volumes and frequencies.”

Diabetes

In age-related metabolic disorders such as diabetes, experts hypothesize that fibroblast growth factor 21 (FGF-21) and myostatin are potential therapeutic targets for insulin resistance. In a novel study published in the European Journal of Sport Science, researchers assigned 44 elderly men to either 12 weeks of resistance training or a control group. 

At baseline, the older men with diabetes harbored higher FGF-21 and myostatin levels, as well as lower muscle strength vs elderly men without diabetes. Resistance training dropped FGF-21 and myostatin concentrations and boosted muscle strength in elderly men with and without diabetes. It decreased HOMA-IR levels, however, in only elderly men without diabetes. (Lower HOMA-IR levels indicate insulin resistance.)

The investigators observed no variation in the resistance training-induced FGF-21 decreases in either elderly men with or without diabetes; however, resistance training yielded a greater decrease in circulating myostatin in those without diabetes. 

Cognitive function

In a systematic review and meta-analysis published in Aging & Mental Health, researchers assessed the influence of resistance training on cognitive function in cognitively healthy and cognitively impaired older adults (aged 60 years or older).

The researchers found that resistance training significantly improved overall cognitive function in cognitive health and cognitively impaired cohorts. On the other hand, short-term memory ameliorated in only cognitively healthy adults. 

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