Muscle and Menopause: Women, weight and wellness
Age-related muscle loss in both men and women has long been described in the medical literature. However more recent research questions many of our notions about the inevitability of this so-called normal aging process.
Two developments are central to this new vision. First, a new understanding of the central role muscle plays in overall health. Second, a much more sophisticated appreciation of how muscle changes with age and how those changes can be addressed.
Most people’s ideas about muscle relate to movement, strength and appearance only. Too often this holds true for medical and fitness professionals as well.
The new conceptualization of muscle stems in part from the discovery of its endocrine function. Muscle secretes hormone-like proteins (myokines) that affect other organs throughout the body. These myokines help regulate body weight, bone density, inflammation and insulin sensitivity, suppress tumor growth, and enhance cognitive function and mood.
That is to say healthy muscle protects against the most common chronic diseases of our time including obesity, type 2 diabetes, cardiovascular diseases, osteoporosis, cancers, dementia and even depression.
For most people a decline in muscle mass begins at 20. Between the ages of 30 and 60, the average adult gains one pound of fat and looses a half-pound of muscle every year. So as you sit down, and it’s fair to say you’ll want to sit down, to celebrate your 60th birthday, you will be packing 30 more pounds of fat and 15 less pounds of muscle than on your 30th.
Happy birthday.
This highlights the problem with tracking weight rather than body composition.
However, these changes do not occur at the same rate and age in men and women. The loss of estrogen at menopause is associated with an earlier accelerated loss of muscle in women compared to men.
The average age of menopause is 51 yet decreases in sex hormones occur a decade or more before. Women live longer than men with an average life expectancy of more than 80 years. This means that most women will spend 30 years of their life in a postmenopausal state. To maximize healthy function in this substantial period requires an understanding of how different systems change with age.
The decline in estrogen experienced at menopause is associated with many changes including loss of bone density, a redistribution of fat, weight gain and increased risk of cardiovascular disease. Equally important changes occur in muscle.
Loss of Muscle Mass/Strength/Power
Women experience a 21% decrease in strength between 25 and 55. This decline is largely due to decreased muscle mass. Research has shown that age-related muscle loss mainly affects a certain type of muscle, type II muscle fibers. Unlike type I (slow-twitch) muscle fibers which enable endurance activity, type II (fast-twitch) fibers provide power, a quick generation of force. This predominant loss of type II fibers makes you slower and weaker.
Contrary to popular belief, power is more important than pure strength for managing activities of daily living such as getting out of a chair, climbing stairs or recovering from a loss of balance to avoid a fall.
While the role of estrogen in this process is not clearly understood, other modifiable factors are well established and inform interventions to preserve muscle, strength and power. The two most powerful determinants of muscle maintenance are physical activity and dietary protein. However not all activity and not all protein packs the same punch.
What do we know about different types of physical training and muscle?
Endurance athletes have the same muscle mass and strength as their sedentary aged-matched controls. However master athletes who were weightlifters have the same muscle structure as people in their twenties.
Such data demonstrate several truths that deserve our attention. Perhaps most importantly, it proves that the typical drop in muscle mass and strength associated with aging can be attenuated. It also indicates that aerobic activity does little to prevent this loss and resistance training does.
We have learned that specific types of resistance training work are better at preventing age-related muscle loss. Because the loss of type II muscle fibers cause most of the decline in mass, strength and power, they are the target. Unlike slow twitch fibers, these fast twitch fibers are stimulated by high intensity work and fast contraction velocities. That is to say, either heavy loads, fast movements or both.
One must remember that the type II fast twitch muscle fibers are made for bursts of force but tire easily. In other words, they do anaerobic work. This means that fewer repetitions per set and longer rest intervals between sets are necessary for their engagement. Most people who think they are doing high intensity interval training are actually doing aerobic exercise due to an inadequate rest:work ratio. When the rest period is too short it is impossible to produce the intensity.
What do we know about nutrition and muscle?
Muscle mass is determined by the balance of anabolism (muscle protein synthesis) and catabolism (muscle breakdown). Essential amino acids in dietary protein stimulate anabolism and are the most important nutritional inputs for muscle maintenance. Leucine in particular, is considered the primary nutritional regulator of muscle anabolism.
This anabolic response decreases with age. However higher doses of essential amino acids (10–15 grams with at least 3 gram of leucine) induce a response comparable to that of young adults.
Absorption of dietary protein also decreases with age. In young adults, slowly digested proteins (e.g. casein) produce greater retention than more rapidly metabolized proteins. In older populations, greater protein synthesis occurs with fast-digested proteins such as whey. Older adults also appear to retain more protein when consumed in liquid rather than solid form.
Approximately one-third of adults over 50 fail to meet the RDA for protein, 0.8 grams per kilogram body weight. A recent scholarly review drawing data from 49 studies with 1863 participants suggests that the adult protein RDA should be doubled. Protein supplementation was shown to significantly increased muscle strength and size when combined with resistance exercise. Supplementation beyond 1.62 grams per kilogram body weight per day provided no further gains.
Timing: As you age there is a greater need to distribute the protein equally across 3 daily meals. Exercise should be in close proximity to one or more of these feedings.
Creatine
Creatine, is a naturally occurring amino acid compound found primarily in red meat and seafood. The majority of creatine is found in skeletal muscle (~95%) with small amounts also found in the brain and testes (~5%). It is one of the most popular nutritional ergogenic aids for athletes. Studies have consistently shown that creatine supplementation improves exercise performance, and/or improves training adaptations. Research has indicated that creatine supplementation can enhance post-exercise recovery, injury prevention, thermoregulation and rehabilitation.
Supplementation increases muscle creatine, enhances fatigue resistance, increases strength/power, increases fat free mass, and enhances functional performance in older adults. In addition to the beneficial effects of creatine supplementation on skeletal muscle in older adults, new data indicate a role of creatine in improving bone health and cognitive processing. Creatine supplementation should be considered a safe and effective nutritional therapy to combat age-related changes in muscle.
Creatine stores can generally be maintained by ingesting 3–5 g/day. Ingesting creatine with carbohydrate or carbohydrate and protein has been reported to more consistently promote greater creatine retention.
The vast majority of studies assessing the efficacy of creatine supplementation have evaluated creatine monohydrate. Claims that different forms of creatine are degraded to a lesser degree than creatine monohydrate or result in a greater uptake to muscle are unfounded. Clinical evidence has not demonstrated that different forms of creatine such as creatine citrate, creatine serum, creatine ethyl ester, buffered forms of creatine, or creatine nitrate promote greater creatine retention than creatine monohydrate. These other forms generally cost more than the preferable creatine monohydrate.
Bottom Line for Anti-Aging Muscle Maintenance
Exercise
· Once a week power workout always using adequate rest periods between sets
· Two days a week regular resistance strength training
Supplements
· Whey protein about 1.5 grams per kilogram body weight in 2–3 divided doses over the course of the day
· Creatine 3–5 gm/day
· Vitamin D3 2000 IU/day Vitamin D deficiency has been linked to age-related loss of muscle mass and strength
Medication
Hormone replacement therapy is an intervention that should be discussed with your physician. If you are not a candidate, supplementation with phytoestrogens may be an alternative. Isoflavones, a phytoestrogen found in soybean products, are thought to help prevent muscle loss by decreasing inflammation that contributes to muscle breakdown.
