The Cooper Institute
 

Founded in 1970 by the "Father of Aerobics"
Kenneth H. Cooper MD, MPH

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Maintain Your Muscles at Every Age!

Posted in
Live well

Thursday, Sep 17, 2015

We lose both muscle mass and strength as we age. In fact, adults begin losing muscle mass in their mid-30s.  By the time they reach 75 years of age, they will have lost ~50% of their total muscle mass.3 This age-related decline in muscle mass is called sarcopenia. As muscle mass decreases, seniors lose strength, which not only affects their ability to perform activities of daily living but also increases the risk of falls.2 Scientists have shown that one of the most effective ways to increase muscle mass and strength is through intense resistance training. However, little is known about how much resistance training is necessary to maintain muscle mass and strength when the volume of resistance training is reduced.

Scott Bickel and his colleagues1 at the University of Alabama studied the effects of decreasing the volume of resistance training in young adults (20-35 years) and seniors (60-75 years). At the beginning of the study, both groups participated in baseline testing followed by a 16-week resistance training program, 3 days per week. Subjects performed 3 sets of 8-12 repetitions of 3 lower body exercises (knee extension, leg press, and squats) at an intensity of 75-80% of the 1 repetition maximum, with 90 seconds rest between sets. When subjects could perform 12 repetitions for 2 of the 3 sets, resistance was increased.

After the 16-week resistance training program, young adults and seniors were randomly assigned to 1 of 3 groups for 32 weeks of follow-up. Group 1 was a control (detraining) group that did no resistance training. Group 2 decreased their weekly training volume (total resistance lifted) to 33% of the volume used during the first 16 weeks of resistance training. The training intensity, number of exercises and sets did not change but training frequency decreased from 3 days to 1 day per week. Group 3 reduced their training volume to 11% of the volume used during the first 16 weeks of resistance training. This group lifted 1 day per week while performing the same number of exercises at the same intensity but decreased the number of sets from 3 to 1.

Researchers performed a muscle biopsy at baseline, after 16 weeks of resistance training, and at week 16 and 32 of the detraining or reduced training period. They also measured strength using the 1 Repetition Maximum. Measurements of thigh lean muscle mass and the size of muscle fibers were also performed throughout the study.

After 16 weeks of resistance training, both the younger and older groups showed significant increases in knee extension strength of 35-40%. Thigh lean mass also increased significantly with the younger subjects gaining 5.6% and older subjects gaining 4.2%.

After Group 1 stopped all resistance training, they began losing muscular strength. However, they did not lose it all. After 32 weeks of detraining, both younger and older subjects were about 23% stronger when tested for knee extensor strength when compared to their baseline strength level measured at the beginning of the study.

After 32 weeks of reduced training volume, the younger adults in Group 2 that exercised 1 day/week but maintained the intensity continued to gain strength and increase muscle fiber size. The young adults in Group 3 that performed 1 set of the same exercises 1 day/week were able to at least maintain their strength increases and improvements in fiber size measured at the end of 16 weeks of resistance training.

In contrast, the older adults that reduced their training volume were not able to maintain their improvements in muscle size. However, they did retain much of the strength improvements even after 32 weeks of resistance training at a reduced volume.

This suggests that strength increases are not dependent on maintenance of muscle mass. Researchers suggest that adaptations in the neuromuscular system such as the ability to recruit more muscle fibers, better coordination of muscles responsible for a movement, and improved relaxation of opposing muscle groups may contribute to increased strength but not muscle mass.

Practice Implications 

Older individuals can achieve similar percentages of strength gains as younger persons when participating in a resistance training program. When the volume of resistance training is reduced in both older and younger individuals, strength is maintained longer than muscle mass. However, older individuals need to perform more sets/week than younger individuals to maintain muscle mass. Given the health concerns associated with reduced muscle mass, some resistance training is better than none as long as it is done consistently and with good form. This study emphasizes the benefits of resistance training in preventing the age-related decline in muscle mass. One thing is for sure as we age – if you don’t use those muscles, you lose them!

Learn more about age-related conditions and activities for this population in our next Older Adults course, beginning September 30. You need not be a health and fitness professional to attend; everyone is welcome!

 

References

1Bickel, C.S., Cross, J.M. & Bamman, M.M. (2011). Exercise Dosing to Retain Resistance Training Adaptations in Young and Older Adults. Medicine and Science in Sports& Exercise. 43 (7), 1177-1187).

2Fried, L.P., Walston, J. (2003). Frailty and failure to thrive. In: Hazzard, W.R., Blass, J.P., Halter, J.B. et al. (Eds.) Principles of Geriatric Medicine and Gerontology. 5th ed. New York, NY: McGraw-Hill, 1487-1502.

3Zagaria, M.A. (2010, Sept. 20). Sarcopenia: Loss of Muscle Mass in Older Adults. Retrieved August 2, 2011, from U.S. Pharmacist Web site:http://www.uspharmacist.com/content/d/senior_care/c/22326/.