Contributed by Julia C. Basso, Post-doctoral Research Scientist, Center for Neural Science, New York University
Strengthen Your Muscles, Strengthen Your Mind
As we age, we lose approximately 5 pounds of muscle mass per decade (Frontera et al., 2000). Because our muscles are metabolically active 24 hours a day, our muscle mass contributes significantly to our resting metabolic rate, which accounts for 70% of the calories we burn per day (Wolfe, 2006). Therefore, as we lose muscle mass, our metabolic rate slows, which then causes us to gain weight, resulting in approximately 15 pounds of body fat per decade (Wolfe, 2006). Fortunately, this loss in muscle mass (and fat gain!) can be halted by incorporating strength training into your weekly exercise regimen. Surprisingly, at any age, only a few months of strength training can combat a decades-worth loss of muscle tissue (Westcott et al., 2009).
Strength-Training Activities
The Centers for Disease Control and Prevention recommends that older adults participate in strength-training activities that work all major muscle groups, including the legs, hips, back, abdomen, chest, shoulders, and arms, on two or more days a week. These exercises should be done in sets (e.g., 8 to 12 repetitions), with each set concluding with muscular fatigue or exhaustion. Some examples of strength-training activities include lifting weights, utilizing resistance bands, using your own body for resistance, heavy gardening or chores, or yoga.
Strength training is beneficial in many ways. First, strength training promotes weight loss because by increasing muscle mass, you increase your metabolic rate. Strength training also enhances one’s sense of balance as well as increasing bone density and reducing the risk of fracture. As falls are common among the elderly, strength training is highly recommended as this type of practice can decrease the risk of falls and decrease injury upon falling. Strength training also reduces symptoms associated with diabetes, arthritis, and cardiovascular disease.
Despite these benefits, on average only 23.9% of the United States population strength trains two or more days per week, with these statistics being lower for women and decreasing as we age (Chevan, 2008; CDC, 2013). With the limited time in our schedules, if we get to the gym at all, most of us opt for the aerobic workout on the treadmill, elliptical, or bicycle. In fact, twice as many individuals meet the guidelines for aerobic activity as compared to strength training (49.4% versus 23.9%). This may be because people are interested in maximizing the caloric burn. However, the physiology of our muscles indicates that strength training actually helps to improve our overall metabolism and thus how efficiently we burn calories throughout the day.
Because aerobic exercise may prove difficult or not be an option for some elderly individuals, resistance or strength training might be a good alternative. Aerobic exercise is a the main focus of neuroscience research. However, researchers have begun to examine the beneficial effects of resistance training on our brains as well.
Study of Strength
One randomized controlled study examined the effect of strength training on cognition in 48 elderly males (ages 65-79) (Tsai et al., 2015). Those individuals in the exercise group underwent three 60-minute strength-training classes per week for 12 months, whereas those in the control group did not receive any intervention. Before and after this 12-month intervention, individuals were tested on the Oddball Task while having their brain activity recorded through electroencephalograpy (EEG). Over the 12-month period, individuals in the control group showed impaired accuracy on the Oddball Task, whereas strength training prevented this decline. In addition, strength training increased reaction time on the test. These results indicate that strength training, similar to aerobic exercise, has the ability to prevent age-related detriments in executive functioning, and specifically in this case attention and information processing.
In tandem with this result, the EEG revealed that a component of brain activity known as the P300, which codes for decision making, decreased in amplitude over the 12-month period in the control group (smaller amplitudes mean worse cognitive functioning). However, the strength training group showed no such decrease. In addition, levels of IGF-1 (insulin-like growth factor 1), a protein that supports brain growth and repair, increased over the 12-month period only for the strength training group, with these levels correlating to the positive changes in test scores and brain activity.
Conclusions
One year is a long time to strength train and after all. The beneficial effects of strength training on the physical body are seen in as little as 10 weeks (Westcott et al., 2009). Some studies indicate that shorter time periods of strength training have beneficial effects on cognition (Forte et al., 2010); however, the majority of studies with cognitive enhancements include at least 6 months of strength training (Kelly et al., 2014). The body quickly improves with resistance training. Thus, studies are warranted that examine shorter periods of strength training on cognition.
As we age, our physical state and mental capacity degrade. We lose muscle mass as well as brain function. The results from this work show that by strength training as little as twice a week, these detriments do not have to occur. We can improve our muscles and minds by lifting a little weight!
References:
Center for Disease Control and Prevention (2013). Exercise or Physical Activity. Retrieved from: http://www.cdc.gov/nchs/fastats/exercise.htm.
Chevan, J. (2008). Demographic determinants of participation in strength training activities among US adults. The Journal of Strength & Conditioning Research, 22(2), 553-558.
Forte, R., Boreham, C. A., Leite, J. C., De Vito, G., Brennan, L., Gibney, E. R., & Pesce, C. (2013). Enhancing cognitive functioning in the elderly: multicomponent vs resistance training. Clinical interventions in aging, 8, 19.
Frontera, W. R., Hughes, V. A., Fielding, R. A., Fiatarone, M. A., Evans, W. J., & Roubenoff, R. (2000). Aging of skeletal muscle: a 12-yr longitudinal study.Journal of Applied Physiology, 88(4), 1321-1326.
Kelly, M. E., Loughrey, D., Lawlor, B. A., Robertson, I. H., Walsh, C., & Brennan, S. (2014). The impact of exercise on the cognitive functioning of healthy older adults: A systematic review and meta-analysis. Ageing research reviews, 16, 12-31.
Tsai, C. L., Wanga, C. H., Panb, C. Y., & Chenc, F. C. (2015). The effects of long-term resistance exercise on the relationship between neurocognitive performance and GH, IGF-1, and homocysteine levels in the elderly. Frontiers in Behavioral Neuroscience, 9, 23.
Westcott, W. L., Winett, R. A., Annesi, J. J., Wojcik, J. R., Anderson, E. S., & Madden, P. J. (2009). Prescribing physical activity: applying the ACSM protocols for exercise type, intensity, and duration across 3 training frequencies. The Physician and sportsmedicine, 37(2), 51-58.
Wolfe, R. R. (2006). The underappreciated role of muscle in health and disease.The American journal of clinical nutrition, 84(3), 475-482.
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