Ken Beilman the Author:

  

"Sarcopenia, Aging, and Resistance Training"


"The goal of life is to die young, as late as possible." - Ashley Montague

Background

The U.S. population is getting dramatically older. Around 2011 the "baby-boom" generation will turn 65, and by 2030 the number of elderly adults will double, with 1 out of every 5 adults over 65 years old. Currently, the "oldest-old" (those over 85 years) number about 5 million, with estimates on growth of the oldest-old over the next 30 years ranging from 8 to 24 million. With these dramatic demographic changes, it is important for the physician to understand sarcopenia and its relation to quality of life.

Sarcopenia

Sarcopenia, or the age-related loss of muscle mass, is derived from the Greek word roots sarx for flesh and penia for loss. Sarcopenia is significantly related to age-related decreases in muscle performance (e.g., strength, power, and endurance). Despite the lack of a direct link to death, sarcopenia, more than any other single factor, is responsible for the frailty and diminished vitality we associate with old age. Loss of muscle performance leads to declining activity, increasing frailty and functional dependence - a vicious cycle which often leads to nursing home admission. Further consequences include gait and balance problems, falls and fractures, and an increased risk of chronic diseases such as osteoporosis and diabetes.

Sarcopenia is commonly seen with advanced age, but that does not mean that sarcopenia is a completely normal part of the aging process. Besides normal physiological aging (e.g., selective loss of muscle fibers) and the accumulation of chronic diseases and medications, chronic sedentariness, an epidemic in our modern society, is a significant contributor to this condition. In essence, inactivity mimics aging, and can be likened to bed rest or space flight, which has negative effects on all systems of the body, including preservation of lean muscle mass. Recent reports from the Center for Disease Control and Prevention indicate that only 15% of adults perform the recommended amount of physical activity, with even less participating in any form of resistance training, crucial to the prevention of sarcopenia.

Sarcopenia and Resistance Training

Resistance (strength) training is typically defined as exercise training in which the resistance against which a muscle generates force is progressively increased over time. Studies have consistently shown that if the basic requirements of intensity and duration are met, older adults show similar gains in muscle performance compared with younger individuals as a result of resistance training. Research strongly suggests that due to the positive functional outcomes, no segment of the population's quality of life can benefit more from resistance training than the elderly.

Lean Body Mass and Function

Muscle mass declines with age, with a preferential atrophy and loss of Type II, fast-twitch fibers. Muscle performance is strongly related to muscle size. Therefore, this age-related loss of muscle mass (sarcopenia) has dire consequences in daily function requiring strength, power, and endurance. In fact, when age and gender are controlled, muscle mass, not function, appears to be the major determinant of strength. In the older adult, increasing muscle mass through resistance training can help battle the ravages of sarcopenia, improving both functional abilities and appearance. Several studies have demonstrated that even the oldest-old adult has the ability to gain muscle mass and to create a favorable anabolic environment for muscle hypertrophy through resistance training.

Strength and Function

Strength is a crucial component of quality of life. As life expectancy increases, the age-related decline in muscle strength becomes a matter of increasing importance. Maintenance of muscular strength significantly impacts an older person's ability to perform activities of daily living and to participate in activities designed to maintain aerobic fitness (e.g., walking). In addition, maintaining and increasing strength to meet and exceed performance goals is important to a growing number of older adults who wish to live a fit, active lifestyle. Studies have repeatedly demonstrated that even in the oldest-old, it appears that not age but initial level of strength is the main determinant in the size of the training adaptation.

Power and Function

Power represents the amount of work a muscle can produce per unit of time, the product of force and velocity. Power is a crucial aspect in the performance of activities that require strength with speed, which relates to many functional and recreational activities of the older adult (e.g., climbing stairs, rising from a chair, walking/gait speed, recovering from a fall, golfing, biking). The ability to develop high muscular power diminishes with age. Recent studies in older adults have used resistance training of varying intensities to significantly increase muscular power and functional outcomes.

Endurance and Function

Endurance is defined as the ability to maintain a given strength or power output for extended periods of time without fatigue. Increases in muscular endurance in the older adult may lead to an enhanced ability to perform submaximal work and recreational tasks. Resistance training in older adults has demonstrated a reduction in cardiovascular stress (e.g., heart rate, systolic blood pressure, and rate pressure product) while walking and carrying a load at a given speed and grade before and after training. Resistance training has consistently improved muscular endurance in the older adult, improving the functional reserve necessary to conquer the stress of the day's repetitive activities.

Conclusion

Sarcopenia has a significant, negative impact on the quality of life of our aging population. Resistance training has proven to be a safe, economical and beneficial form of exercise in helping to combat sarcopenia and enhance muscle performance in older adults.


*References available upon request.

Kent Adams, PhD, Associate Professor Exercise Physiology, University of Louisville
Kenneth Beilman, MD, Private Practice of Internal Medicine.

Reprinted from Louisville Medicine, February 2001, a monthly publication of Jefferson County Medical Society.