Why Menopausal Women Need Polarized Training

Donating blood is great. But you don’t need to give a pint to gain fitness as new research may suggest.

Women are not small men. It’s been my mantra for well over a decade. In recent years, the scientific community has been catching up and calling attention to sex differences in exercise adaptation, such as in a recent study published in the Journal of Sports Sciences.  

The study, which was covered in Outside and has been the subject of myriad emails filling my inbox, is titled Marked improvements in cardiac function in postmenopausal women exposed to blood withdrawal plus endurance training. The authors state right out of the gate that mature women are “mainly unresponsive to endurance training”, so maybe they need some form of extra cardiac stress to go along with it, in this case, giving blood.

In the study, 15 moderately active women between the ages of 52 and 75 had a standard blood draw of about a pint (500 ml or 10 percent of the donor’s blood supply) withdrawn. They had three weeks to partially recover their hemoglobin mass and oxygen carrying capacity and then participated in an eight-week training program that included two to five sessions of short high-intensity intervals with a 2:1 work-to-recovery ratio (specifically three sets of 30-second sprints on a stationary bike with 15 seconds recovery and three minutes active recovery between sets) each week.

In the end, the women were able to consume more oxygen at any given heart rate than they could before the blood draw/exercise training (though it was only statistically significant at higher heart rates). The main finding was that their left ventricle, which is the chamber of the heart responsible for pumping oxygenated blood to tissues throughout the body, remodeled and its function improved.

That’s great and makes sense. When you give blood, your body restores the plasma fairly quickly, but it takes longer to restore the oxygen-carrying red blood cells, so you have less oxygen to go around and your heart has to work harder to give your muscles the oxygen they need for activity.

Women Are Built for Endurance

Because the study didn’t include a control group who didn’t give blood, we’re not really sure what would have happened if they simply did the high-intensity training program. The study does reference research, including this meta-analysis, showing that women appear to have less left ventricle adaptations to endurance training than men. But we need to dive in further and determine how many of those studies were looking at the effects of endurance training as defined by steady state, longer, lower-intensity exercise as opposed to high-intensity exercise that this blood-draw study used.  

Why is that important? Because women are naturally designed for endurance, to go long and steady. Past research shows that women’s muscles extract oxygen from the blood faster than men (so we might not need that remodeling in response to pure endurance exercise). Women have proportionally more oxygen-efficient slow-twitch fibers and burn more fat and less carbohydrate than men during endurance exercise. We’re built for endurance. That’s why you’re seeing women outright winning ultra-endurance events like Race Across America (RAAM), and women are outpacing men in super long ultrarunning races.  

That’s also why I included a whole chapter on high-intensity (specifically very short sprint-level intensity) exercise for women in the menopause transition in my book Next Level and my updated Menopause 2.0 course. Women in this demographic are not going to get real performance (or even optimum health) benefits from traditional “cardio” exercise like brisk walking. Women, especially women in the menopause transition who are losing their sex hormones, need very strong stress like high-intensity activity to improve their cardiovascular outcomes like better blood vessel compliance, better heart rate responses to postural shifts and energy demands, and an improvement in cardiac muscle integrity. 

I feel like this study was a big missed opportunity to continue HIT research on postmenopausal women. In my professional opinion, the blood loss probably wasn’t a big factor, especially since the exercise testing was anaerobic, not aerobic work, in a temperate lab environment (so there was not a competition for blood between sweating and muscle work). The women were also not trained. They were moderately active; just hitting the 150 minutes of exercise per week (no indication of how intense or long those minutes entailed). So, the stress of giving blood and then doing an intense 8-week HIIT program was bound to yield improvements. They would have likely improved from the training alone.

I would have liked to see three groups: a control group that just carried on with their usual activity; a second group that did the HIIT training only, and a third group that did the blood donation and HIIT training. Then we would have more insight into fitness adaptations for post-menopausal women from this study.

Practical Ways Menopausal Women Can Improve Endurance Performance

Women in this demographic benefit most from polarized training—staying out of the gray, kinda hard/kinda easy training zone and going truly hard and then truly easy to allow their body to recover and make adaptations. 

The best type of HIIT training for menopausal women is the type used in the blood-draw/training study, very short (30 seconds max) all out efforts with short recovery. Tabatas are a classic HIIT method of this type. (To do them: Warm-up, push as hard as possible for 20 seconds. Recover for 10 seconds. Repeat 6 to 8 times. Rest 5 minutes, and work up to repeating 2 to 3 more rounds. 

I recommend short intervals because once you extend past 60 seconds you get a greater increase in the stress hormone cortisol, which is fine for boosting energy in the moment, but you don’t want it to stay elevated longer than necessary, especially in menopause when cortisol levels can already be elevated and more difficult to manage.

Sauna sessions, especially if you perform them after training when you’re already slightly dehydrated, can help accelerate your adaptations. When you sit in the sauna, your body sends blood to your skin to help you sweat and avoid overheating. If you’re already a little dehydrated (i.e. have lower blood volume) from the exercise session, your kidneys will sense that you need more red blood cells to get oxygen to your organs and will produce more erythropoietin (EPO) and plasma volume, which boosts your blood volume for training and performance gains.

Finally, be sure to lift weights. By the time you turn 40 (if not before), you start losing muscle. That loss accelerates during the menopause transition. If you want to be able to train hard enough to make meaningful adaptations and optimize performance, you need the muscle mass to help you push hard.