Resistance training has many health benefits. For one, it protects against frailty by reducing age-related muscle loss. It also helps us stay strong and functional throughout life as we tackle its many challenges. No wonder! The movements we do every day require muscle strength and the ability of muscles to work well together. Strength training improves the way muscles function by increasing strength and by reinforcing neurological patterns of movement. Muscles learn how to work more efficiently as a unit in response to training.
But, there’s another benefit of resistance training. Research shows it improves the way cells handle glucose. As such, resistance training may lower the risk of developing type 2 diabetes. We think of aerobic exercise as being the best type of exercise for lowering the risk of type 2 diabetes, but resistance training is good for metabolic health too. In fact, a recent study shows how resistance training improves the way cells process glucose, what we refer to as insulin sensitivity.
Resistance Training and Insulin Sensitivity
Resistance training is an exercise that works muscles against resistance. The resistance can include weights, resistance bands, or bodyweight exercises. In response to progressive overload, muscles adapt and become stronger and thicker. Such a response is good for metabolic health as well. But, how does resistance training upgrade insulin sensitivity and metabolic health?
Scientists now have new insights into the mechanism. In a recent study, researchers found that resistance training boosts levels of a protein called APPL1, a key regulator of insulin sensitivity. When this protein rises, as it does with resistance training, cells can more easily take up glucose. This means the pancreas doesn’t have to pump out as much insulin to get glucose into cells. That’s favorable for metabolic health and for weight control.
In fact, the researchers in the study identified four pathways that are turned on by resistance training. These pathways boost APPL1, so the pancreas doesn’t have to produce as much insulin to get glucose into cells. Insulin is a hormone that promotes fat storage too, so you want lots of it circulating in your bloodstream. The caveat is this study was carried out in rats. You can’t say with certainty that It plays out the same way in humans, although researchers believe that it does.
These results aren’t surprising. There’s already evidence that working muscles against resistance enhances insulin sensitivity and, in turn, metabolic health. A study published in Diabetes Care found that resistance training boosted how responsive cells are to insulin in older adults with type 2 diabetes. The improvements occurred even though the participants lost no weight and didn’t change their diet. What’s exciting is the upgrades in insulin sensitivity are independent of weight.
A Combination of Exercises May Be Best
It’s encouraging that resistance training improves insulin sensitivity as some people are unable to do aerobic exercise and need another way to lower their risk of type 2 diabetes. According to a 2013 meta-analysis, a combination of resistance training and aerobic exercise is best for enhancing insulin sensitivity, both in metabolically healthy people and those with type 2 diabetes.
Compound exercises, those that work more than one muscle group at the same time, and movements that work the lower body have the greatest impact on metabolic health and insulin sensitivity. In contrast, isolation exercises, like biceps curls, have less impact since they work one muscle group and the biceps are a small muscle.
Here’s the catch. To maintain improvements in insulin sensitivity, exercise, both resistance training, and aerobic exercise, must be ongoing. You can’t exercise for a few weeks and then stop. Insulin sensitivity returns to its pre-exercise state within a few days of stopping exercise. On the other hand, if exercise leads to meaningful weight loss, insulin sensitivity would improve due to that factor.
How much improvement in insulin sensitivity can you expect in response to resistance training? In a study of folks with type 2 diabetes, an average of 5 weeks of moderate-intensity resistance training boosted insulin sensitivity by 48% and the improvements were independent of weight reduction. In another study, untrained men with type 2 diabetes who resistance trained twice per week upgraded their insulin sensitivity despite a 15% increase in calorie consumption.
Other Ways to Boost Insulin Sensitivity
Two of the biggest factors that influence insulin sensitivity are age and body weight. Carrying lots of tummy fat is detrimental to insulin sensitivity. But other lifestyle factors play a role as well. For example, not sleeping enough boosts cortisol production. This, in turn, reduces insulin sensitivity.
As you might expect, diet is a key factor as well. Highly processed foods and foods rich in sugar place an added burden on the pancreas to produce insulin. They also lead to weight gain, another risk factor for insulin resistance and type 2 diabetes.
On the other hand, a diet rich in fiber, healthy protein sources, and non-starchy vegetables improve how insulin functions, and you get bonus points for eating foods high in magnesium. Studies show a link between insulin resistance and low levels of magnesium. Research shows that when magnesium is deficient it causes enzymes involved in glucose metabolism to not function effectively. Magnesium deficiency also changes the sensitivity of insulin receptors on the surface of cells. Research shows that up to half the population doesn’t get enough dietary magnesium. Good sources include green, leafy vegetables, nuts, seeds, and whole grains.
The Bottom Line
Now, you have another reason to work your muscles against resistance. Aerobic exercise isn’t the only form of exercise that improves insulin sensitivity and metabolic health, resistance training does too. The best approach is to do both, as each has unique benefits to your health and wellbeing.
References:
Everyday Health. “Study Reveals Potential Mechanism in Strength Training That Can Help Reduce Insulin Resistance”
American Physiological Society. Volume 314, Issue 6. June 2018. Pages E564-E571.
Medscape.com. “Resistance Training Benefits Type 2 Diabetics”
J Obes Weight Loss Ther. 2015 Jul; 5(0 5): S5-003.
Diabetes Self-Management. “Increasing Insulin Sensitivity”
J Lab Physicians. 2015 Jul-Dec; 7(2): 75–78.
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Related Cathe Friedrich Workout DVDs:
STS Strength 90 Day Workout Program
All of Cathe’s Strength & Toning Workout DVDs
Total Body Workouts
Lower Body Workouts
Upper Body Workouts
