Printed with permission from the Cooper Institute
We lose both muscle mass and strength as we age. In fact, adults begin losing muscle mass in their mid 30s and by the time they reach 75 years of age have lost on average 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 affects their ability to perform activities of daily living and increases fall risk.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 start 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) using an intensity of 75-80% of their 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%. 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 1 Repetition Maximum lifts, thigh lean muscle mass and the size of muscle fibers 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 gaining 4.2%.
After Group 1 stopped all resistance training, they started losing muscular strength. However, they did not lose it all. After 32 weeks of detraining, both groups were about 23% stronger when tested for knee extensor strength compared to their baseline strength level measured at the start 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 like the ability to recruit more muscle fibers, better coordination of muscles responsible for a movement, and more relaxation of opposing muscle groups may contribute to increased strength but not muscle mass.
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 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!
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/.