July 2023

Three (More) Cheers for Resistance Training

A large meta-analysis of studies on resistance training (RT) exercise in adults found 16 that met the criteria. The overall conclusion was that RT conferred a  “10–17% lower risk of all-cause mortality, cardiovascular disease (CVD), total cancer, diabetes, and lung cancer,” otherwise labeled non-communicable diseases (NCDs). There was also an attempt to pin down dose-response relationships sufficient to make national or international recommendations. These are topics we’ve covered here, here, here, and here.

The studies that were included in the analyses had to be prospective in design, had at least 2 yrs of follow-up, had to evaluate the effects of RT alone or in combination with cardio, and published in English. While there were 1252 studies that were evaluated for inclusion, several were excluded for reasons such as duplicates, using the same cohort to extract multiple studies, etc.

RT was associated with a 15% lower risk of all-cause mortality, 17% lower risk of CVD, 12% lower risk of all cancers, 10% lower risk of lung cancer with insufficient data to show its benefits for other site-specific cancers, and 17% lower risk of diabetes.

Most studies showed a minimum of 10 minutes/wk but ideally 30-60 mins/wk in 1-2 training sessions/wk was most effective. Combined RT+cardio conferred even lower risks of NCDs. In fact, more than 60 mins/wk and more than 3/wk didn’t seem to reduce the risk of NCDs much more than this basic prescription.

Of course, there are many other reasons for doing RT more frequently, but overall disease risk reduction doesn’t take much of a commitment. As they say, just do it…some but not too much.

Br J Sports Med July 2022

It Takes a Lot of Guts to Exercise

A review study in Preventive Nutrition and Food Science (June 2020) looked at “the relationship between obesity and the gut microbiome, and the role of probiotics, prebiotics, and synbiotics for preventing and treating obesity.” The gut microbiome is the new vogue target of health and disease concerns. The quality and variety of microbes inhabiting our intestines, where nutrient absorption occurs, is believed to be connected to how our bodies, and brains, function.

The results of this review showed that the microbiome had an “impact on nutrient metabolism and energy expenditure.” Obesity correlated with a less diverse, less healthy biome and high fiber intake, high protein diets, and exercise contributed to greater diversity. Not surprisingly, the typical Western diet, high in sugars, saturated fats, salt, and processed foods, contributed to a less diverse microbial environment in the gut. More discussion about these factors affecting the gut can be found here and here.

Specific classes of microbes are associated with a healthy or less healthy microbiome. For example, a decrease in bacteroidetes and an increase in firmicutes have been linked to the Western diet and obesity. Yet those who participate in 30-60 mins/day of moderate-to-vigorous cardio exercise, from young, elite athletes to obese subjects in a weight management program, invert those ratios such that they had increases in bacteroidetes and decreases in firmicutes, while bariatric surgery, which leads to weight loss, did not alter these components. In sum, “exercise-induced compositional and functional changes to the human gut microbiota dependent on obesity status and exercise sustainment, and independent of diet.” Whether it does so independent of weight/fat loss is unclear.

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