Metabolic syndrome (MetS) is estimated to affect one-third of the United States population, with a worldwide prevalence ranging from <10% to as much as 84%. These estimates vary depending on the demographics of the population studied, including geographic region, urban vs. rural setting, gender, age, race, and ethnicity), as well as the MetS definition and criteria that are used in the research study. Globally, the International Diabetes Federation (IDF) estimates that one-quarter of the world’s adult population meets their criteria for MetS.
Hallmark clinical features of MetS include glucose intolerance, insulin resistance, central obesity, dyslipidemia, and hypertension. The dysfunctional cardiometabolic state of MetS leads to an increased risk of developing type 2 diabetes (T2D) and cardiovascular disease (CVD). T2D is the seventh leading killer of adults in the United States, and adults with T2D have twice the risk of dying of CVD than adults without T2D.  These alarming statistics indicate a critical need to identify effective, sustainable interventions to reduce the prevalence of MetS.
Lifestyle modifications including routine and effective forms of physical activity, healthful nutrition, stress attenuation, and adequate sleep all play an integral role in optimizing body composition, reducing chronic inflammation, and ultimately mitigating the incidence of MetS.
In the prospective study by Bakker et al., investigators hypothesized that exercise type and duration affect the risk of MetS development. Previous cross-sectional research demonstrates that higher muscular strength and resistance exercise are associated with lower prevalence of MetS. Additionally, longitudinal cohort studies reveal a lower risk of T2D with higher levels of resistance exercise. However, less well understood is whether resistance training, alone or in combination with aerobic exercise, reduces the risk of developing MetS. To explore this relationship further, researchers from the US, UK, and Netherlands studied a large cohort of US adults from the Aerobics Center Longitudinal Study.
The study sample included 7418 individuals; 19% (1384) were women. Participants had an average age of 46 and had previously received comprehensive medical examinations at the Cooper Clinic in Dallas, Texas between 1987 and 2006. The participants were predominantly white, non-Hispanic, well-educated and employed in, or retired from, professional or executive positions. The comprehensive medical examination included body composition assessment, blood pressure measurements, electrocardiography, physical examination and detailed medical history questionnaire. Blood chemistry analysis was also obtained for each individual and included triglycerides, HDL and fasting glucose levels.
Resistance exercise (RE) activity was assessed through self-reports gathered through a medical history questionnaire, with participants responding to these questions:
- Weekly frequency of RE (0 – ≥ 5 times per week)
- Duration for each RE session (0 – ≥ 180 minutes/week)
- Use of free weights or weight training machines during each RE session
Frequency and duration of aerobic exercise were also assessed via self-report on the medical history questionnaire. Resistance and aerobic exercise data was analyzed in relation to the incidence of MetS at baseline and at follow-up.
Results from the analyzed information found that 15% (1147 individuals) developed MetS during the median follow-up of 4 years. RE, alone and in combination with aerobic exercise, had statistically significant effects on the reduction of MetS risk. Major findings includes:
- Performing any weekly RE was associated with a 17% lower risk of developing MetS
- Completing 1-59 minutes per week of RE was associated with a 29% lower risk of developing MetS. Higher volumes of RE (up to ≥ 180 minutes per week) did not confer additional benefits for MetS incidence
- When compared to no RE, RE performed 4 days per week was associated with a 38% lower risk of MetS development
- There was no significant difference in the risk of developing MetS between individuals with the same total duration of RE but with different frequencies: spreading the RE into several sessions across the week vs. performing all RE within one weekly session (i.e. “weekend warriors”)
- Individuals who met the 2008 US Physical Activity Guidelines for resistance and aerobic exercise (RE sessions ≥twice weekly AND ≥500 minutes/week of aerobic activity) had a 25% lower risk of development of MetS when compared to individuals who did not meet either guideline
Why is this Clinically Relevant?
- Inclusion of resistance exercise (regardless of duration or frequency) into one’s physical activity regimen is associated with a lower risk of developing MetS
- A linear relationship between RE and risk of developing MetS is lacking, so the “more is better” exercise philosophy may not apply
- Clinicians are encouraged to discuss the benefits of adding any regular RE into their patient’s weekly activities, regardless of the possible duration and frequency of that RE
- Clinicians should encourage all patients to incorporate resistance and aerobic activity to their weekly exercise plan when possible to further reduce the risk of MetS development
Bakker EA, Lee D, Sui X, et al. Association of Resistance Exercise, Independent of and Combined with Aerobic Exercise, With the Incidence of Metabolic Syndrome. May Clin Proc. August 2017:92(8):1214-1222.
 Kaur J. A Comprehensive Review on Metabolic Syndrome. Cardiology Research and Practice. Volume 2014 (2014), Article ID 943162, 21 pages http://dx.doi.org/10.1155/2014/943162
 Diabetes, Heart Disease and You. https://www.cdc.gov/features/diabetes-heart-disease/index.html (Accessed 9/26/2017)