The relationship between muscle, menopause and glucose are inextricably linked if you seek optimal health. A few weeks ago, we shared a post discussing the importance of muscle for metabolic health. Muscle — and, in particular, having more muscle — is linked to better insulin sensitivity and glucose utilization. The body also burns more calories at rest when it has a higher amount of muscle, making it easier to maintain a healthy body weight and also maintain bone density.

However, as we age, the body naturally loses muscle and can become more insulin resistant — meaning that the cells do not take up and use glucose as effectively. Menopause can also drastically affect muscle loss and insulin resistance. The good news is that exercise, especially strength training, can positively influence these physiological changes and help to both prevent and reverse age-related muscle loss, insulin resistance, and the body’s ability to use glucose as energy.

A review of glucose and insulin

Before we continue, let’s review the function of insulin in the body and why it’s important. Insulin is responsible for “shuttling” glucose into the body’s cells, so that the glucose can be used for energy. The term “insulin sensitivity” refers to how easily the body is able to accomplish this task; the more sensitive you are to insulin, the more quickly and efficiently your cells can take up and use the glucose that’s been brought inside by insulin.

“Insulin resistance,” on the other hand, means that when the body releases insulin, the cells aren’t as responsive. Instead of bringing the glucose into the cell quickly, the process is slowed. More glucose stays outside and isn’t able to be used for energy. This can lead to fatigue, inability to focus, and cravings. It can also become a harbinger for other metabolic disorders, such as type 2 diabetes.

Menopause and insulin

During menopause, the body experiences a variety of physiological and psychological changes. A deficiency in estrogen leads to hot flashes, night sweats, migraines, heart palpitations, and incontinence or increased frequency of urination. Women experiencing menopause can also have psychological symptoms such as increased anger or irritability, depression, anxiety, and difficulty sleeping or concentrating.

Post-menopause, it becomes easier for the body to gain fat and lose muscle for three reasons: 1) muscle protein synthesis drops, 2) the body cannot utilize fat as effectively for fuel during exercise, and 3) insulin sensitivity decreases, meaning that the body is constantly storing food as adipose tissue (a.k.a., fat).

Previously, we’ve covered training and exercise needs for women post-menopause. This will be important for later, because in addition to preserving bone density and muscle mass, exercise also helps improve insulin sensitivity and helps the body use glucose more effectively.

How does muscle, exercise, and menopause affect glucose?

Sarcopenia — the loss of muscle — is usually attributed to aging. Age-related declines in muscle mass can start as early as age 25, and continue declining from that point on. A study published in 2019 noted that, “By 80 years of age, approximately 40% of the vastus lateralis [thigh] muscle … has been lost.” (1) Losing muscle drastically reduces overall mobility and strength, resulting in a limited capacity for daily living activities.

Think about going up the stairs of your home, or carrying the groceries in from the car. The activities we don’t think twice about now can become exponentially harder as we reach our elderly years.

This same 2019 study also made a striking point: “Declining physical activity with aging is a main contributing factor in determining the degree of age-related insulin resistance.” In other words, sarcopenia from reduced exercise and activity is one of the biggest drivers of reduced glucose utilization and insulin resistance with aging. It makes sense, because if there’s less muscle on the body, there’s less lean mass available for insulin to shuttle glucose to.

So, continuing to strength train throughout our lifespan can prevent age-related sarcopenia, which keeps the body mobile and metabolically healthy. Research has also shown that adults who participate in moderate- or high-intensity training have improved insulin sensitivity, compared to their sedentary counterparts. Additionally, a study from 2006 examined the effects of moderate- vs. high-intensity aerobic training in post-menopausal women, along with a low-intensity training control group. The researchers found that the high-intensity group experienced a greater benefit to insulin sensitivity when compared to the moderate-intensity one, though both groups had statistically significant improvements. It should also be noted that women in this 2006 study were inactive prior to their involvement in the training program. These metabolic results were seen in as little as nine months, which was the duration of the study. (2)

The body is not as metabolically flexible after menopause, meaning it has difficulty switching between carbohydrates and fats as the energy source for activities. A small study published in February of this year looked at differences in metabolic flexibility between sarcopenic and non-sarcopenic senior adults during exercise. This study concluded that the adults with sarcopenia had a greater reliance on carbohydrates during exercise; they were not able to tap into their fat stores as effectively, and their fasting blood glucose levels were much higher than the non-sarcopenic group. The sarcopenic group was more insulin resistant. In contrast, the non-sarcopenic group — who had maintained their muscle mass into their senior years — was able to switch between carbohydrates and fat, regardless of if they were at rest or exercising, fed or fasted. And, to quote the paper, “Even after a high-carbohydrate meal, [the non-sarcopenic group] continued to utilize fat to a higher degree than [the sarcopenic group].”(3)

Bringing it all together

The importance of strength training and physical activity, especially in the later years of life, are something we cannot emphasize enough. They are an unparalleled intervention for healthy aging and preventing age-related metabolism and mobility decline. In post-menopausal women, physical activity not only helps to preserve bone health, but also allows the body to maintain metabolic flexibility and switch between carbs and fats for energy during exercise.

A well-designed exercise program — at any age — should include strength, conditioning and cardiovascular work, and mobility. Women especially need to focus on heavy strength training for optimal health. These recommendations are well-documented in the research, and an educated trainer can help you design the best program regardless of where you’re starting from. For expert guidance and to get started with a trainer, reach out to us at go@hyatttraining.com.

References

  1. Consitt LA, Dudley C, Saxena G. Impact of Endurance and Resistance Training on Skeletal Muscle Glucose Metabolism in Older Adults. Nutrients. 2019;11(11):2636. Published 2019 Nov 3. doi:10.3390/nu11112636
  2. DiPietro L, Dziura J, Yeckel CW, Neufer PD. Exercise and improved insulin sensitivity in older women: Evidence of the enduring benefits of higher intensity training. Journal of Applied Physiology. 2006;100(1):142-149. doi:10.1152/japplphysiol.00474.2005
  3. Shoemaker ME, Pereira SL, Mustad VA, et al. Differences in muscle energy metabolism and metabolic flexibility between sarcopenic and nonsarcopenic older adults. Journal of Cachexia, Sarcopenia and Muscle. 2022;13(2):1224-1237. doi:10.1002/jcsm.12932.

Hyatt Training is a team of certified, enthusiastic and innovative health and fitness professionals in Portland, Oregon. Get in touch by emailing us at Go@HyattTraining.com.