Sarcopenia: A Covert Threat to Your Life, Liberty, & Pursuit of Happiness
Marlene Harris, NSCA-CSCS, NASM-CES
Author’s Note: Resistance training is a very important element of your fitness and weight management goals. It shouldn’t be ignored, but all too often, it is. The following article was adapted from a longer, more technical research paper I wrote for a graduate level class in Exercise Epidemiology. For those who’ve not been exposed to this type of writing, I’ve toned down the “science-speak”. The little numbers in parentheses after various sentences refer to the exact studies that support my statements. The list of these references was omitted from this rendering, but if interested, I can make it available to you. I hope this article brings you greater insight as to why I speak about resistance training with such enthusiasm and conviction! M.H.
The Privilege of Longevity
An old adage advises: “never fret about growing older, as the privilege is denied to many”. However, as we journey through life, moving ever closer towards this privilege, a menace lurks deep within our physiology. Without clamor, fanfare, pain, or other overt physiological drama, it gradually and silently steals our quality of life if we allow it. This thief goes by the name of sarcopenia, a little-discussed process that effects one single population as we move beyond our third decade of life: all of us.
Sacrcopenia is the natural loss of lean body mass, specifically, Type II (fast twitch, or strength) muscle, that accompanies aging due to a combination of physiological, nutritional, hormonal, and lifestyle factors (22, 4). The development of muscle mass and strength capacity are reported to peak in the mid-twenties to early thirties, and if left to natural processes begin a gradual decline thereafter (22, 4). According to Wikipedia, the term sarcopenia has Greek origins, and means "poverty of flesh” (22). This natural decline becomes more precipitous after 65 to 70 years of age, with about a third of your total (original) muscle mass being lost in your elder years(4). Most research literature reports that the rates of strength losses for men and women are fairly similar, with losses appearing first and more significantly in the larger, lower body muscles than those of the smaller, upper body muscles (4, 6, 11). Because the larger muscle groups are more affected, this has significant implications for the loss functional strength, metabolic capacity (ability to burn calories), and as a result, for general wellness and weight management. Among the myriad factors associated with this process, inactivity (specifically, a lack of resistance, or heavier weight-bearing exercise), and nutritional status (specifically, protein intake) are reported as being most prominent and readily controllable (2, 3, 4, 7, 11, 12, 14, 19, 20). This is the bright spot in this otherwise bleak outlook-we can have a great deal of control over this process if we take a hands-on approach.
At Higher Risk, by Nature…
While sarcopenia affects both men and women at relatively equal rates of decline, women are particularly predisposed to the debilitating effects of this process for several reasons. However, stay with me here, gentleman readers, because you’re not out of the woods here by any means, and remember that these considerations will affect the women in your life.
Women have a naturally, and significantly lower starting complement of lean body mass (aka: muscle) as compared to men, meaning that gals have less muscle to lose out of the gate. In addition, various studies on physical activity trends indicate that women tend to be less physically active than men, and this tendency increases as age increases. The combination of less lean body mass and inadequate amounts of physical activity can set women up for significant impairment.
…but There’s Plenty of Misery for Everyone!
For both genders, the loss of lean body mass directly relates to both calorie burning capacity and functional strength for life activities. This sets the stage for increased rate of weight gain as we age. Increasing weight gain can decrease our efforts at engaging in physical activity. Here you have it: reduced metabolic rate, subsequent weight gain, and decreasing activity levels. Result: increased risks for a spectrum of lifestyle-related illnesses such as diabetes, heart disease, and other inflammatory processes, along with a general decrease in your quality of life, and satisfaction with it. Specifically, here’s what you have to lose:
1). Functional strength for daily activities, such as the ability to tend to your home, carry out general daily activities (such as carrying groceries, picking up a grandchild or pet, going up or down stairs, or getting up out of a chair).
2). The ability to participate in favored activities and/or hobbies.
3). Money, through the increased financial burden imposed by the need for more, and more frequent health care.
5). Your sense of self-worth: you lose self-efficacy (your sense of confidence in your ability to carry out activities) and self-esteem (your general opinion of yourself).
In sum, the effects can be broad and the impact far-reaching in terms of your health and quality of life. As such, the process of sarcopenia should be viewed as a significant threat to your personal health.
Your Muscle: A Forgotten Element of Fitness
Many prominent researchers on the impact of physical activity on illness and mortality have devoted entire careers to examining the impact of general physical activity at work and at play on health and lifespan, with an emphasis on middle-aged men. This is hardly surprising, as men are particularly vulnerable to heart disease and related conditions at mid-life (although women are fast gaining “equality” in this dubious race). Consistent with the theme of concerns regarding coronary disease, much of the research and media attention has focused on aerobically-based, heart stimulating activities in the form of structured cardiovascular conditioning or simply increasing everyday and/or leisure-time physical activities. However, the research on muscle loss, strength, and resistance training is sadly under-reported.
While heart health and cardiovascular work are undeniably important to health and should be included as a part of any regular physical activity program, equal consideration should be given to preserving and improving our muscle mass, strength, thus our functional capacity as we age.
Key Consderations: What the Research Says
The research on sarcopenia provides a wealth of valuable insight into the process of muscle degradation and what we can do to prevent it.
Many processes, simple path to success: Beginning with a detailed report on the complexity of the processes involved in sarcopenia, in 2006, Solomon and Bouloux (17) presented a beefy review which offered an outline of the many factors involved in the process of muscle growth and decline. They highlighted the importance of supporting cells and cell chemistry, mechanical stimulation (aka, resistance training), calcium and vitamin D status, and growth hormone, among others. In their conclusion, the authors noted that the “interaction between growth factors (created by supportive nutrition) and mechanical stimulation (resistance training) is of significant importance”. Simplified translation: eat healthy, lift weights, keep your muscle.
Forget hormone replacement, lift weight (and eat your protein!): In a 2005 review of various studies investigating the use of testosterone replacement, growth hormone replacement, or resistance training as remedies for sarcopenia, Borst (2) concluded that resistance training was the most effective strategy. He reported that:
1). Testosterone replacement yielded only modest increases in muscle strength and mass and came with significant concerns regarding destructive side effects at higher doses.
2). Growth hormone replacement yielded no increases in strength, did nothing to improve the effects of resistance exercise, and also carried with it a high incidence of destructive side effects.
He also commented that in older people, inadequate nutrition (protein intake and supporting nutrients) was the primary factor that kept people from the optimal benefits of resistance exercise.
More nutrition, nutrition, nutrition: Supporting the importance of nutrition in sarcopenia, various studies have focused on the relationship between dietary protein and lean body (muscle) mass. In a study done in 2007, Campbell and Leidy (3) reported that adequate protein intake, in connection with resistance training, are important considerations in slowing sarcopenia. Further, they suggested that the current recommendation of .08 g of protein per kg of body weight (which has been reported by some registered dieticians and nutritional references to be generous), may not be sufficient to support the desired results of resistance training.
In a similar study, also in 2007, Lord et al. (8) focused on the association between the intake of dietary animal protein and muscle mass in older women. They compared intake of animal and vegetable sources of protein with the muscle mass index (a measure of lean body mass) of each woman, and found that animal protein intake was the independent predictor of a higher muscle mass index. In their conclusion they suggested that, in particular, animal sources of protein were superior for the preservation of lean body mass. Other studies have reported this result as well.
You’re never “too old”, and it’s never “too late”: In terms of the effects of resistance training on the loss of lean body mass, many studies have examined this relationship among various age groups. While utilizing a variety of approaches, these studies all end up in agreement on one central point: in terms of curtailing, or even reversing the loss of muscle mass and related strength declines, regular resistance exercise does a body good at any age. In 2006, Reeves, Narici, and Maganaris (15) reported that resistance training offered a protective effect against various cellular and molecular markers of muscle degradation and consistently resulted in improvements in muscle mass and strength. They further noted that “older muscle…maintains a high degree of plasticity (responsiveness) in response to increased loading…”, meaning that age alone does not necessarily restrict the ability to generate new muscle growth. In 2006, Taaffe (20) also echoed these observations in his examination of resistance exercise as a treatment strategy for sarcopenia. In his conclusion, he likewise commented on the responsiveness of the aging neuromuscular system, and suggested that resistance exercise via a variety of forms, at a sufficiently taxing level of intensity, done regularly, on a weekly basis, was a prescription for improvements.
In still another report of favorable response to resistance training despite aging, in 2007, Melov, et al.(10) took skeletal muscle biopsies from both and younger older adults, and used gene expression profiling to examine and compare the features of the samples of both groups. Further, he exposed a sub-group of the older participants to a six month resistance exercise program. When he examined both pre and post exercise gene expression, he discovered that, in the older group exposed to the resistance training program, many of the genes known to be affected by both age and exercise showed a reversal of their gene expression(s) to profiles that more resembled those of the younger group.
While science reveals that everyone will need to reckon with the process of sarcopenia, this brief glimpse into the research on this process offers considerable hope. The remedy can be found in the form of appropriate amounts and intensities of resistance exercise and proper nutritional support (specifically, adequate protein intake). Functional strength, ability, and metabolic capacity are as vital to health as sound cardiovascular functioning. What good is a healthy heart if you don’t have the strength to get up out of a chair, walk up and down stairs, or carry or pick up objects without injuring yourself? With respect to protecting your muscle mass, and considering the studies featured in this commentary, the opening advisory regarding to “never fret about getting older…” should be augmented with the gym rat’s time-honored advisory to “use it, or lose it”.
References: A 24 item reference section exists for this paper, but was omitted here for the sake of space and bevity. The reference section can be made available upon request, just e-mail us!