Muscle up to beat hot flushes
Women who hang on to their muscle mass during the menopausal transition are protected against hot flushes and night sweats.
Hot flushes (or 'hot flashes', for our American friends) and night sweats - collectively known as 'vasomotor symptoms' (VMS) - are the bane of many women's lives during the menopausal transition.
Up to 80 per cent of US women and around 74 per cent of Australian women under 55 experience these episodes of profuse heat accompanied by sweating and flushing, predominantly around the head, neck, chest, and upper back, at some point in their passage through menopause. 42 per cent of Australian women are still experiencing VMS in their early to mid 60s, and a sizeable minority of women are still suffering well into their 70s.
Various theories have been put forth as to why hot flushes and night sweats occur during the menopausal transition, but amazingly, the physiology of these bothersome events is still not fully understood by researchers.
Hot flushes and night sweats are not simply a nuisance, an inconvenience or a source of embarrassment. The severity of vasomotor symptoms is strongly correlated with reduced health-related quality-of-life, impacting significantly on sleep, mood and cognitive function:
Sleep quality and quantity are adversely affected by vasomotor symptoms; I've seen many women over the years whose night sweats are so intense that they drench the bed multiple times each night, forcing them to change the bedclothes every time. These interruptions to sleep wreak havoc on women's mood, capacity to cope with stress, energy level, immune function and food choices.
Perimenopausal women who experience vasomotor symptoms are more likely to develop depression than those who aren't plagued by hot flushes and night sweats.
Cognitive function (for example, the ability to think clearly, remember important information, and find the right word to use) is also adversely affected by vasomotor symptoms.
And on top of all that, hot flushes and night sweats are also associated with an increased risk of cardiovascular disease and reduced bone density, which in turn increases the risk of bone fractures.
Well, that's the bad news.
The good news is that women aren't helpless in the face of this menopause monster. They can, quite literally, muscle out hot flushes and night sweats.
The Study of Women's Health Across the Nation (SWAN) is a multi-site, longitudinal, epidemiologic study which has been tracking the health of over 3000 American midlife women, from diverse ethnic and socioeconomic backgrounds, since 1996. Women enrolled in SWAN attend regular visits in which various aspects of their health are assessed.
SWAN has resulted in the publication of many scientific papers and book chapters that shed light on women's health and well-being during this epochal phase of their lives.
In one of these publications, ‘Association of lean body mass to menopausal symptoms: The Study of Women's Health Across the Nation’, researchers tracked changes in lean body mass - that's every part of your body that isn't fat tissue - over time, and found that women who maintain higher levels of lean body mass during the menopausal transition may be protected against the development of vasomotor symptoms.
Specifically, the researchers used bioelectrical impedance analysis (BIA) to measure the body composition of 2533 women enrolled in SWAN, at their sixth visit. These measurements were repeated each time the women attended for subsequent visits, so that changes in their body composition could be tracked over time.
They then calculated the skeletal muscle index (SMI - skeletal muscle mass [kg]/height [m2]), which expresses the relationship between skeletal muscle mass and height; taller women will on average have more muscle mass than shorter women, simply because their bodies are larger.
The striking relationship between skeletal muscle index and the likelihood of developing hot flushes and night sweats is depicted in the figure below. Each line on the graph represents the probability of participants reporting vasomotor symptoms at each visit, as a function of their skeletal muscle index (SMI).
Almost 70 per cent of women who had the lowest SMI were experiencing some vasomotor symptoms by Visit 10, compared to less than 10 per cent of women with the highest skeletal muscle index.
In other words, women who maintained or built muscle mass as the study progressed, were able to keep hot flushes and night sweats at bay.
The reason/s why maintaining muscle mass may protect women against hot flushes and night sweats are not fully understood, but the foremost theory at present is that muscle mass protects against oxidative stress (inadequate defence against free radicals and other reactive oxygen species); oxidative stress is linked to greater severity of vasomotor symptoms.
This oxidative stress theory may help to explain an earlier finding which I covered in my article Beat menopausal hot flushes with fruit-and-veg-powered weight loss: Women who lost weight when assigned to a dietary intervention which emphasised increased intake of fruits, vegetables and whole grains (all rich in antioxidants, which combat oxidative stress) were more likely to eliminate their vasomotor symptoms. Those who lost weight without switching to a high-antioxidant diet were no more likely to be free of hot flushes and night sweats by the end of the study.
My personal experience
I entered the post-menopausal phase of my life almost three years ago. After a couple of years of increasingly infrequent menstrual periods, one day I realised that I had not had a period for over 12 months - the official definition of being post-menopausal.
To this day, I have never experienced a hot flush or night sweat. I have also not suffered any of the other maladies that many women complain of at this time of life - no weight gain, no sleep disturbance, no joint or muscle aches and pains, no fatigue, no depression or anxiety. For me, menopause simply signposted the end of my reproductive capacity, which is completely OK by me since I have already brought two beautiful children into the world!
Did I just get lucky? Of course, I can't rule that out. After all, between one fifth and one quarter of women don't experience vasomotor symptoms. But my mother had a terrible time with her 'change of life', so I know I'm not genetically predisposed to an easy menopausal transition.
Here's what I do know: I maintained regular weight training and aerobic activity, as well as a wholefood plant-based diet rich in fruits and vegetables, throughout my menopausal transition.
I have not had a body composition scan since the bioimpedance analysis shown below, which was done about three years before my last menstrual period. But neither my diet, exercise regimen nor body weight and measurements have changed since then, so my best guess is that it is still a reasonably accurate representation of my body composition, which was assessed as 'thin and muscular' by the system's algorithm.
The bottom line
I have been banging the drum for resistance training - the best way to maintain or increase lean body mass - for decades. All adults should be engaging in regular resistance training, and the older we get, the more important it becomes.
Loss of lean body mass is not just associated with vasomotor symptoms in women, but also with cognitive decline, increased risk of bone fractures (particularly hip fractures), and depression, in both men and women.
Any or all of the following activities can be used to maintain and build muscle mass:
Body weight exercises such as push-ups, sit-ups, squats, lunges, pull-ups and chin-ups
Resistance bands (I use these ones)
Weight training with free weights (dumbbells, barbells, kettlebells, sandbags and the like) and/or resistance machines
Aquarobics, preferably using foam dumbbells to increase the resistance
Weighted vests
Walking is a wonderful and almost universally accessible physical activity with enormous benefits for physical and mental health, but it is not sufficient for maintaining muscle mass as we age. If you want to reap all the physical, psychological and cognitive benefits that flow from maintaining (or even increasing) your muscle mass and strength as you get older, you need to add resistance training to your weekly activity schedule. As the old maxim states, 'Use it or lose it!'