It’s not just aging. These changes reflect several biological shifts, many of which are linked to perimenopause. Understanding what is happening inside the body can help women make informed decisions about habits they should adopt and how they should adjust their exercise regime.
I turned 40… What’s happening to me?
1. Muscle mass starts to decline. Beginning as early as the thirties, adults lose approximately 3% to 8% of muscle mass per decade. This loss tends to accelerate after age 50. Muscle tissue is metabolically active, meaning it burns calories even at rest. As muscle decreases, resting metabolic rate also declines. Lower muscle mass can present with reduced strength & functional fitness, lower energy expenditure or “calorie burn,” and can ultimately lead to unwanted weight gain. If you’re not using your muscles after 40, you’ll lose them [1].
2. Bone density drops. Bone is constantly being remodelled, meaning it breaks down and rebuilds itself on an ongoing basis. During our younger years, bone formation exceeds bone breakdown, but in midlife, this balance begins to shift. Women are especially at risk of bone loss in midlife because estrogen plays a very important role in maintaining bone density. As estrogen levels eventually decline during late perimenopause, bone resorption increases. Women can lose up to 20% of their bone density during the menopause transition and early postmenopausal years, increasing the risk of osteoporosis and fractures later in life [2].
3. Body fat distribution shifts. Hormonal shifts in the perimenopause transition often lead to unwanted weight gain in the abdomen. Estrogen is largely responsible for ensuring body fat goes to the lower body, and when estrogen declines, other hormones like cortisol and insulin may impact where body fat accumulates. This abdominal weight gain is a source of frustration for many women due to aesthetic concerns, but what’s worse is the negative health outcomes associated with increasing abdominal fat. Visceral fat surrounds the organs, and is associated with insulin resistance & diabetes, cardiovascular disease and chronic inflammation [3].
4. You don’t recover as quickly. Your body’s ability to repair damaged tissues and recover from exercise slows down as you get older. This is due to age-related reduction in collagen production, decreased protein synthesis, and changes in hormones that are responsible for growth and repair. Not only that, several other changes that are often associated with age (such as poor sleep) also negatively affect the body’s ability to recover. However, this does not mean that intense exercise should be avoided! It simply means recovery strategies become increasingly important and must be considered when determining your optimal exercise strategy [4].
5. Cardiovascular risk increases. Many women have a low baseline cardiovascular risk, and suddenly end up with high blood pressure and high cholesterol during or after the perimenopause transition. This is largely due to estrogen’s supportive effects on cholesterol metabolism and the health of blood vessels in the body. This makes exercise more important than ever, as it’s one of the best ways to mitigate this increased cardiovascular risk [5].
So, what should I do?
Strength train. It’s tempting to focus solely on burning calories when you notice your body weight increasing or your waistline growing. What’s more important than calorie burn is maintaining or improving your muscle mass. Increasing muscle mass increases your metabolic rate, leading to more calories burned even while you sleep. Not only does it help with body composition, it also helps preserve bone mass, support insulin sensitivity, metabolic health and keep you as independent and able-bodied as possible as you age [6].
Don’t skip cardio. Many perimenopause experts have shared the importance of strength training, but cardiovascular training should not be neglected to accommodate this! Cardiovascular training improves heart health and blood pressure, has supportive effects on sleep and mood, and is an integral part of any weight management program. Cardiovascular training could include walking, swimming, rowing, cycling, dancing and more. Varying the intensity of your training is an excellent way to keep exercise interesting, but also to improve your VO2 max and ensure your body can adapt to a variety of training intensities [7].
Prioritize mobility and recovery. With perimenopause, joint integrity and collagen formation can change, making it easier to injure yourself and harder to recover from exercise. Emphasizing mobility work — which can include stretching, yoga, dynamic warm ups, and more — is critical. Not only can focusing on mobility support your ability to exercise over the long-term, it can also support balance, posture, joint range of motion and functional independence over the lifespan. In terms of recovery, women in perimenopause often experience disrupted sleep, which can impair muscle repair, which can then impact exercise performance and increase the risk of injury. Prioritizing sleep and being sure to take recovery days is an essential part of any fitness plan, especially in midlife [8], [9].
Many women feel like they have to add more and more to their exercise regime to keep up with the shifts that happen in midlife. This isn’t true! The goal is to work smarter, not harder. Adopting a planned, scheduled exercise regime that includes variations of the above is a great start.
A balanced weekly routine might include:
- 2–3 days of strength training
- 2–4 days of cardiovascular exercise
- Daily walking and general movement from daily activities (e.g. yard work, tidying the home, grocery shopping, etc.)
- Mobility work several times per week (before and after training sessions, or before bed)
- Keeping a regular bed time and optimizing sleep conditions every night
You can’t stop perimenopause and aging from happening, but you can take steps to ensure the impact of these changes is minimal. Exercise is one of the most powerful and accessible forms of medicine in general, but especially in this stage of life. Strength training preserves muscle and bone mass, cardiovascular exercise protects heart health, and general exercise supports metabolic function, mood, and overall quality of life. It’s time to stop looking at exercise as a tool to lose weight. If you’re a woman over 40, you should begin to think of it as an investment in your future self, to help you age gracefully and independently. Your body may be changing with time, but the right approach will help it remain strong, functional and healthy!
References
- Wilkinson, Daniel J., M. Piasecki, and PJ6202460 Atherton. “The age-related loss of skeletal muscle mass and function: Measurement and physiology of muscle fibre atrophy and muscle fibre loss in humans.” Ageing research reviews 47 (2018): 123-132.
- Khosla, Sundeep, and B. Lawrence Riggs. “Pathophysiology of age-related bone loss and osteoporosis.” Endocrinology and Metabolism Clinics 34.4 (2005): 1015-1030.
- Toth, Michael J., et al. “Menopause‑related changes in body fat distribution.” Annals of the New York Academy of Sciences 904.1 (2000): 502-506.
- Li, Donna Ching Wah, et al. “Age-associated differences in recovery from exercise-induced muscle damage.” Cells 13.3 (2024): 255.
- Nair, Anjana R., Aiswarya J. Pillai, and Nandini Nair. “Cardiovascular changes in menopause.” Current cardiology reviews 17.4 (2021): 23-30.
- Hunter, Gary R., John P. McCarthy, and Marcas M. Bamman. “Effects of resistance training on older adults.” Sports medicine 34.5 (2004): 329-348.
- Woodward, Amie, et al. “Effect of physical activity on cardiorespiratory fitness and markers of cardiovascular disease risk during menopause: A systematic review and meta-analysis of randomised-controlled trials.” Journal of Science in Sport and Exercise 8.1 (2026): 9-31.
- Verma, Annanya, et al. “Rehabilitation strategies in post menopausal women: a systematic review and meta-analysis of randomized trials.” European Journal of Obstetrics & Gynecology and Reproductive Biology (2026): 115278.
- Kodete, Chandra Shikhi, et al. “Hormonal influences on skeletal muscle function in women across life stages: a systematic review.” Muscles 3.3 (2024): 271-286.
