At the present time, there is overwhelming scientific evidence that physical inactivity is a major risk factor for the development of cardiovascular disease, some cancers, type 2 diabetes, and other adverse health outcomes. Most of this evidence is based on studies of moderate to vigorous aerobic physical activity (MVPA) such as walking, jogging, cycling, stair climbing, and lap swimming. MVPA is also strongly associated with a reduced risk of all-cause, cardiovascular disease, and cancer mortality.
Current guidelines for physical activity recommend a minimum of 150 minutes per week of moderate-intensity aerobic activity or a minimum of 75 minutes per week of vigorous-intensity physical activity. Paired with that guideline is a recommendation to perform strength training activities at least 2 days per week. While there is evidence that strength training is associated with improvements in muscle size and strength, bone density, blood pressure, and blood glucose control, less is known regarding the relationship between strength training and various mortality outcomes.
In past blogs, we have mentioned a statistical technique called a meta-analysis. Briefly, a meta-analysis takes several relatively small but similar studies and combines them into one large study. Recently, a group of Australian researchers published a meta-analysis on the relationship between strength training and all-cause, cardiovascular disease, and cancer mortality. Ten high-quality published studies were combined for the meta-analysis; subjects ranged from 18 to 85 years old, and were apparently healthy at baseline. Eight of the ten studies included both men and women. Subjects were asked various questions regarding their participation in strength training activities as well as MVPA, and then followed for mortality. The follow-up time ranged from 7 to 17 years.
For those who reported some versus no strength training at baseline, there was a 15%, 19%, and 14% decreased risk of all-cause, cardiovascular disease, and cancer mortality, respectively, during the follow-up (Figure 1). The research group also examined the data for a dose-response relationship, and found that about 60 minutes of resistance training per week was the ‘sweet spot,’ with a risk reduction of 26% for all-cause mortality.
The effects of various combinations of strength training and MVPA were also examined. When compared to those performing neither strength training nor MVPA, all-cause mortality risk was reduced by 18% in those reporting strength training but no MVPA, by 25% in those reporting some MVPA but no strength training, and by 40% in those reporting both strength training and MVPA. The same general patterns were observed for both cardiovascular disease and cancer mortality. Thus, performing both strength training and MVPA gives us the greatest benefit with regard to reducing mortality risk.
In every study, there are limitations. The authors of this meta-analysis acknowledged that participation in strength training and MVPA activities was based on questionnaires and not by actual observation or measurement. The questions asked at baseline varied a bit among the ten studies included. Additionally, participation in strength training and/or MVPA could have changed during the follow-up. Nevertheless, this meta-analysis provided the strongest evidence to date that resistance training is associated with a reduced mortality risk. Whether it be free weights, resistance machines, resistance bands, or other strength training modalities, all adults are urged to include strength training in their physical activity routine!
Shailendra, P., et al. Resistance Training and Mortality Risk: A Systematic Review and Meta-Analysis. Am J Preventive Med. 2022;63(2):277−285.