with the strongest effects observed when the two types of exercise are combined, new research shows.
“The novel finding from our study is that weight lifting is independently associated with lower all-cause and CVD-specific mortality, regardless of aerobic activity,” first author Jessica Gorzelitz, PhD, said in an interview.
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“What’s less surprising – but consistent and nonetheless noteworthy – is that weight lifting in combination with aerobic exercise provides the lowest...risk for mortality in older adults,” added Dr. Gorzelitz, an assistant professor of health promotion in the department of health and human physiology at the University of Iowa, Iowa City.
Those who undertook weight lifting and aerobic exercise in combination had around a 40% lower risk of death than those who reported no moderate to vigorous aerobic activity or weight lifting. The findings were recently published online in the British Journal of Sports Medicine.
Physical activity guidelines generally recommend regular moderate to vigorous aerobic physical activity, in addition to at least 2 days per week of muscle-strengthening exercise for all major muscle groups for adults to improve health and boost longevity.
However, few observational studies have examined the association between muscle strengthening and mortality, and even fewer have looked specifically at the benefits of weight lifting, Dr. Gorzelitz said.
Benefit of weight lifting stronger in women than men
To investigate, Dr. Gorzelitz and coauthors evaluated data on participants in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, which, initiated in 1993, and involved adults aged 55-74 at 10 U.S. cancer centers.
Thirteen years into the trial, in 2006, participants completed follow-up questionnaires that included an assessment of weight lifting (not included in a baseline survey).
Among 99,713 participants involved in the current analysis, the mean age at the time of the follow-up questionnaire was 71.3 years. Participants had a mean body mass index of 27.8 kg/m2 and 52.6% were women.
Only about a quarter of adults (23%) reported any weight lifting activity within the previous 12 months, with fewer, at 16%, reporting regular weight lifting of between one and six times per week.
Participants’ physical aerobic activity was also assessed. Physical activity guidelines (2018) recommend at least 150-300 minutes per week of moderate-intensity aerobic physical activity or 75-150 minutes per week of vigorous intensity aerobic activity or an equal combination of the two. Overall, 23.6% of participants reported activity that met the guideline for moderate to vigorous physical activity, and 8% exceeded it.
Over a median follow-up of about 9 years, 28,477 deaths occurred.
Those reporting weight lifting had a 9% lower risk of combined all-cause mortality and CVD mortality, after adjustment for any moderate to vigorous physical activity (each hazard ratio, 0.91).
Adults who met aerobic activity recommendations but did not weight lift had a 32% lower risk of all-cause mortality (HR, 0.68), while those who also reported weight lifting 1-2 times per week in addition to the aerobic activity had as much as a 41% lower risk of death (HR, 0.59), compared with adults reporting no moderate to vigorous aerobic activity or weight lifting.
The benefit of weight lifting in terms of cancer mortality was only observed without adjustment for moderate to vigorous physical activity, and was therefore considered null, which Dr. Gorzelitz said was somewhat surprising. “We will examine this association further because there could still be a signal there,” she said, noting other studies have shown that muscle strengthening activity is associated with lower cancer-specific mortality.
Of note, the benefit of weight lifting appeared stronger in women versus men, Dr. Gorzelitz said.
What are the mechanisms?
Underscoring that the results show only associations and not causation, Dr. Gorzelitz speculated that mechanisms behind a mortality benefit could include known favorable physiological changes of weight lifting.
“If people are weight lifting [to a degree] to reap strength benefits, we generally see improvement in body composition, including reductions in fat and improvements in lean tissue, and we know that those changes are associated with mortality, so it could be that the weight lifting is driving the strength or body composition,” she said.
The full body response involved in weight lifting could also play a key role, she noted.
With weight lifting, “the muscles have to redirect more blood flow, the heart is pumping harder, the lungs breathe more and when the muscles are worked in that fashion, there could be other system-wide adaptations,” she said.
Furthermore, social aspects could play a role, Dr. Gorzelitz observed.
“Unlike muscle strengthening [activities] that can be done in the home setting, weight lifting typically has to be done in recreational facilities or other community centers, and considering that this is an older adult population, that social interaction could be very key for preventing isolation.”
Important limitations include that the study did not determine the nature of the weight lifting, including the duration of the weight lifting sessions or type of weight, which could feasibly range from small hand-held weights to heavier weight lifting.
The study also couldn’t show how long participants had engaged in weight lifting in terms of months or years, hence, the duration needed to see a mortality benefit was not established.
Nevertheless, the study’s finding that the group with the lowest benefits was the one reporting no aerobic or weight lifting exercise underscores the benefits of even small amounts of exercise.
“I think it’s really important to promote the importance of adding muscle strengthening, but also of any physical activity,” Dr. Gorzelitz said. “Start small, but something is better than nothing.”
The authors reported no relevant financial relationships.
A version of this article first appeared on Medscape.com.