Sarcopenia is a very common syndrome involving low muscle mass and reduced muscle function in older people. The extent of sarcopenia in elderly populations can reach as high as 68%. Risk factors include low levels of physical activity and low body mass index (BMI). Combined programs of resistance training, aerobic exercise, balance and flexibility exercises are recommended for older adults to prevent or treat sarcopenia, performed several times per week.
- 1 CONTENTS
- 2 What is sarcopenia?
- 3 What is the prevalence of sarcopenia?
- 4 What are the risk factors for sarcopenia?
- 5 What factors influence muscle size and strength?
- 6 Is aerobic exercise useful for the treatment of sarcopenia?
- 7 Is resistance-training useful in the treatment of sarcopenia?
- 8 Are combined exercise interventions useful for sarcopenia?
- 9 Do reviews of exercise confirm its usefulness for sarcopenia?
- 10 Evidence-based recommendations for exercise
- 11 Conclusions
- 12 References
What is sarcopenia?
Sarcopenia is a syndrome involving low muscle mass and reduced muscle function, typically observed in the ageing individual. Sarcopenia usually involves a generalized loss of muscle rather than a localized loss of muscle or muscle group-specific loss of muscle. Moreover, it is thought that this loss of muscle follows primarily from disuse atrophy. Sarcopenia is a key problem in geriatrics and leads to an increased risk of several adverse health outcomes, including physical disability, poor health-related quality of life and increased mortality.
What is the prevalence of sarcopenia?
The following table sets out the results of various studies that have assessed the prevalence of sarcopenia in populations of elderly people of varying ages and in different geographies:
|Iannuzzi-sucich et al.||US Male adults aged 64-94 years||26.8%|
|Iannuzzi-sucich et al.||US Female adults aged 64-94 years||22.6%|
|Iannuzzi-sucich et al.||US Female adults aged >80 years||31%|
|Iannuzzi-sucich et al.||US Male adults aged >80 years||52.9%|
|Melton et al.||US Adults aged >65 years age/sex adjusted||6-15%|
|Baumgartner et al.||New Mexico elderly adults >70 years||13-24%|
|Baumgartner et al.||New Mexico elderly adults >80 years||>50%|
|Kenny et al.||Non-obese Female adults aged 59-78 years users of estrogen replacement therapy||23.8%|
|Janssen et al.||United States male adults aged >60 years||7%|
|Janssen et al.||United States female adults aged >60 years||10%|
|Lau et al.||Chinese male adults >70 years||12.3%|
|Lau et al.||Chinese female adults >70 years||7.6%|
|Kim et al.||Korea elderly adults||6.9%|
|Kim et al.||Korea elderly adults with Type II Diabetes Mellitus (T2DM)||15.7%|
|Monaco et al.||Elderly women with acute hip fracture||58%|
|Landi et al.||Italian male nursing home residents aged >70 years||68%|
|Landi et al.||Italian female nursing home residents aged >70 years||21%|
|Castillo et al.||US community-dwelling adults aged 55-98 years||6%|
|Castillo et al.||US community-dwelling males aged >85 years||16%|
|Castillo et al.||US community-dwelling females aged >85 years||13%|
Based on these studies it appears that the prevalence of sarcopenia ranges from 7 – 68% depending on age, geography and circumstances of the individuals involved. Older adults, individuals living in residential nursing homes and individuals who have experienced fractures tend to have an increased prevalence of sarcopenia.
What are the risk factors for sarcopenia?
The main risk factor for sarcopenia is of course increasing age. However, there are also other key risk factors. The following table sets out the results of various studies that have assessed the risk factors of sarcopenia in populations of elderly people of varying ages and in different geographies:
|Iannuzzi-sucich et al.||The researchers investigated the prevalence of sarcopenia and corollary characteristics in older 195 and 142 men and women respectively, aged 64-93 years. Participants were measured for appendicular skeletal muscle, body mass index and performance and health related tests.||The researchers found that sarcopenia was significantly and inversely related to BMI in both men and women. In women, sarcopenia was related to circulating levels of esterone, estradiol and 25-hydroxy vitamin D. In men positive correlations were found between sarcopenia and single leg stance time, leg press strength and power, testosterone levels, health-related quality of life questionnaire and scores in the Short Physical Performance Battery, and the Physical Performance Test.|
|Kenny et al.||The researchers investigated the prevalence and corollaries of sarcopenia in 189 non-obese women aged 59-78 years who had been long-term users of estrogen replacement therapy.||The researchers found that skeletal muscle mass was significantly correlated with lower BMI, handgrip strength, lower and upper extremity weakness and power, testosterone level, and age of starting treatment. In multivariate analysis, muscular strength, BMI and testosterone explained ~50% of sarcopenia.|
|Janssen et al.||The researchers examined the relationship between sarcopenia and functional impairment and disability in 4,504 participants aged >60 years.||The researchers found that likelihood of functional impairment and disability was approximately two times greater for men and three times more likely for women who are sarcopenic compared to older men and women with normal skeletal muscle mass.|
|Lau et al.||The researchers examined the risk factors for sarcopenia among 262 men and 265 women community dwelling Chinese adults aged >70 years.||The researchers observed that significant positive associations between being underweight and sarcopenia in both men and women.|
|Kim et al.||The researchers investigated the prevalence and risk factors of sarcopenia in Korean adults with and without T2DM. The researchers recruited 414 and 396 elderly adults with T2DM and controls respectively.||The researchers found that skeletal muscle mass was significantly lower in participants with T2DM. Further, they found that T2DM was independently associated with developing sarcopenia.|
|Monaco et al.||The researchers investigated the association of sarcopenia with osteoporosis and hip fracture in 313 elderly women. The researchers performed dual energy x-ray absorptiometry scans to determine skeletal muscle mass 20.9 days following hip-fracture.||The researchers found that 180 of the women were sarcopenic and 230 were osteoporotic, representing 58% and 74% respectively.|
|Landi et al.||The researchers investigated the prevalence and risk factors of sarcopenia in 122 adults aged >70 years living in a teaching nursing home in Roma, Italy.||The researchers found that the prevalence of sarcopenia was much greater in males compared to females, as well as those with cerebrovascular conditions and osteoarthritis. Significantly correlations were observed for participants with low BMI, and negative associations with >1 hour of daily physical activity.|
|Castillo et al.||The researchers investigated the prevalence and risk factors of sarcopenia among 73 community dwelling men and women aged between 55 – 98 years in the Rancho Bernardo study.||The researchers found that fat-free mass of the men and women averaged 61.7 and 43.5 kg respectively. The prevalence of sarcopenia was 6%, rising to 13% and 16% for women and men aged >85 years respectively. The researchers concluded that individuals with sarcopenia had significantly less fat mass, lower BMI and tended to not smoke. Men with sarcopenia were twice as likely to have fallen in the past year compared to those who without sarcopenia. The researchers observed that grip strength but not quadriceps strength was significantly lower in individuals with sarcopenia compared to those without.|
|Raguso et al.||The researchers conducted a cross-sectional longitudinal study investigating the changes in body composition, skeletal muscle mass and BMI in elderly 74 men and 66 women adults aged >65 years over a 3 year period.||The researchers found that a significant but mild decline in muscle mass and an increase in fat body mass occurred over the 3 years.|
Based on these studies it appears that individuals with low physical activity and body mass index (BMI) are at a greater risk for developing sarcopenia. Functional impairment and low scores on functional tests such as single leg stance time and handgrip strength, as well as a history of falls, may also be risk factors.
What factors influence muscle size and strength?
The following studies have explored the factors that influence muscular size and strength in elderly people, either indirectly by using acute studies of signalling proteins or directly by exploring the long-term effects of training programs:
|Farnfield et al.||The researchers investigated the effect of protein supplementation and resistance exercise in the phosphorylation of mRNA translational signalling proteins in skeletal muscle of 16 young (18 – 25 years) and 15 (60 – 75 years) older men.||The researchers found that the stimulus to protein supplementation and resistance exercise was less pronounced in older men compared to younger men.|
|Lexell et al.||The researchers investigated the skeletal muscle fibre area, number, proportion and size of the vastus lateralis muscle of 43 previously active men aged between 15-83 years.||The researchers reported that muscle fibre number stays fairly constant to the sixth decade but from 60-80 years decline by 50%.|
|Narici et al.||The reviewers reviewed the literature in relation to age-related declines in muscular size and strength.||The reviewers reported that the loss in muscle mass that gives way to sarcopenia involves both a loss in muscle fiber size (atrophy) as well as muscle fiber number. They observed that age-related declines in muscular size occur largely because of a decrease in type II muscle fiber size. Similarly, they report that type II muscle fiber areas experience greater decreases compared to type I muscle fiber areas as a result of preferential denervation of type II muscle fibers and a shift towards type I muscle fiber characteristics.|
|Arthur et al.||The reviewers explored the area of oxidative stress as a contributor to muscle wasting in ageing populations.||The reviewers reported that there is convincing evidence to suggest that oxidative stress can increase muscle protein catabolism thought the exact interplay that leads to muscle wasting is still unclear.|
Based on these studies and reviews, sarcopenia appears to involve a loss of type II muscle fiber area and muscle fiber number as a result of denervation. An inability to stimulate muscle protein synthesis via signalling and increased oxidative stress may lead to accelerated muscle wasting.
Is aerobic exercise useful for the treatment of sarcopenia?
The following studies have explored the beneficial effects of aerobic exercise in the treatment or prevention of sarcopenia:
|Coggan et al.||The researchers investigated the effect of aerobic exercise training in elderly men and women aged 64 years. The subjects performed walking/jogging exercise at 80% of their maximum heart rate for 45 minutes 4 times per week for 9 – 12.||The researchers found that the subjects increased their maximal oxygen consumption by 23% after the intervention. While the researchers reported no change in type I muscle fiber percentage, they did observe an increase in the percentage of type IIA and a decreases in IIB muscle fiber percentage. The researchers observed increases in muscular cross-sectional area of type I and IIA muscle fiber areas of 12% and 10%, respectively.|
|Short et al.||The researchers investigated the effect of aerobic exercise training in 78 men and women aged 19 – 87 years. The subjects performed cycling exercise at 80% of their maximum heart rate for 45 minutes 3 – 4 times per week for 4 months.||The researchers found that protein turnover correlated with fat-free mass and declined at a rate of 3% per decade. Even when adjusting for fat-free mass, the decline in protein turnover with age was still significant. Furthermore, the researchers reported a significant increase of aerobic capacity of 9% and an increase of mixed muscle protein synthesis of 22% following cycling exercise.|
|Harber et al.||The researchers investigated the effect of aerobic exercise training in 7 older women aged 71 years. The participants performed cycling exercise for 12 weeks which created an increase in aerobic capacity.||The researchers found that quadriceps muscle volume increased by 12% while knee extensor power increased by 55%. The size of type I muscle fiber area was significantly increased but the size of type IIA muscle fiber area was unchanged. The researchers found that the peak force of single muscle fibers was unchanged but peak force of single muscle fibers per unit cross-sectional area decreased.|
|Lepretre et al.||The researchers investigated the effect of short term aerobic interval exercise training in 19 women and 16 men aged 65 years. The subjects performed cycling exercise twice per week for 9 weeks, exercising for 6 x 4 minutes at the first ventilatory threshold interspersed with 1 minute at the second ventilatory threshold.||The researchers found that following the 9 weeks, maximal values of minute ventilation, oxygen uptake, heart rate, systolic blood pressure, maximal tolerated power, lactate at maximum tolerated power and the power at the first ventilator threshold significantly improved in both genders.|
Based on these studies it appears that aerobic exercise is beneficial for older adults and has positive effects on both aerobic and anaerobic capacity and leads to increases in muscle fiber size and improvements in functional characteristics.
Is resistance-training useful in the treatment of sarcopenia?
The following studies have explored the beneficial effects of resistance-training in the treatment or prevention of sarcopenia:
|Holviala et al.||The researchers investigated the effect of progressive resistance-training in groups of 26 middle-aged and 22 older-aged women, aged 53 and 64 years respectively. The subjects performed 21 weeks of progressive resistance-training utilising lower loads with higher movement velocity, 2 times per week test.||The researchers found that 1RM, isometric strength and rate of force development increased by 28, 20 and 31% in the middle-aged group and by 27, 20 and 18% in the older-aged groups, respectively.|
|Newton et al.||The researchers investigated the effect of a mixed-methods (hypertrophy, strength and power) progressive resistance training program in groups of 8 young and 10 older males, aged 30 and 61 years, respectively. The subjects performed 10 weeks of progressive resistance-training 3 times per week.||The researchers found that isometric squat strength increased by 23% and 40% in the young and old men, respectively.|
|Roth et al.||The researchers investigated the effect of progressive resistance-training performed 3 days per week in 8 young men, 6 young females, 9 older men, and 10 older females, aged 20 – 30 and 65 – 75 years, respectively. The subjects performed 6 months of progressive resistance-training, 3 times per week.||The researchers reported significant increases in muscle volume and cross-sectional area in both aged and gender groups, with no significant difference between the magnitudes of improvement.|
|Bird et al.||The researchers investigated the effect of progressive resistance training or flexibility training performed in 32 older adults aged 68 years. The participants performed either 16 weeks of either progressive resistance-training or a flexibility program then performed the opposite program for a further 16 weeks. The program was conducted in a community-based facility to investigate the change in balance and strength following either program. The researchers measured sway velocity and medio-lateral range, as well as Timed Up-and-Go, 10 times sit-to-stand, step test, and lower limb strength during isokinetic testing.||The researchers found that both programs significantly improved sway, Timed Up-and-Go, 10 times sit-to-stand and step test, while only progressive resistance-training led to a significant improvement in lower body strength.|
|De Vos et al.||The researchers investigated the effect of different training intensities in elderly adults performing an explosive resistance-training program designed to increase peak power. The researchers recruited 112 healthy older adults aged 69 years. The subjects performed explosive resistance training (5 exercises for 3 sets of 8 repetitions with a fast concentric and a slow eccentric) 2 times per week. The exercises were performed with either 20, 50 or 80% of 1RM.||The researchers found that force at peak power was significantly greater in all training groups compared with the control group but the improvements were similar between groups.|
|Miszko et al.||The researchers investigated the effect of either strength training or power training in older adults aged 72 years.||The researchers found that there was a significant improvement in peak anaerobic power in both groups but there was no difference between the groups following the 16 week training intervention. However, they found that performance on the Continuous Scale Physical Performance test score was significantly greater following power training than following strength training.|
|Bottaro et al.||The researchers investigated the effect of either power training or traditional resistance training with matched work output for 10 weeks in inactive healthy elderly adults aged 60 – 76 years. The subjects performed resistance-training 2 times per week for 3 sets of 8 – 10 reps with either a 2 – 3-second contraction or as fast as possible.||The researchers reported significantly greater improvements in the functional performance tests. They found that performance in the arm curling and chair stand tests improved significantly more in the power-training group (by 50% and 43%, respectively) compared to the traditional resistance training group (by 3% and 6%, respectively).|
|Henwood et al.||The researchers investigated the effect of power training in 24 elderly adults aged 60 – 80 years. One group of subjects performed a power training program comprising 7 upper and lower body exercises performed for 3 sets of 8 reps at 35, 55 and 75% of 1RM for 8 weeks. Another group acted as a control.||The researchers found that dynamic muscle strength increased in all exercises. They also observed significant improvements in knee extension power and in performance in functional tests including floor rise to standing, 6m walk, repeated chair rise, and lift and reach, while there were no significant improvements in the control group.|
|Reid et al.||The researchers compared the effects of lower body power-training and progressive resistance-training in elderly subjects with mobility limitations. They therefore recruited 57 subjects aged 74 years. The subjects completed resistance-training 3 times per week. One group performed power training while another group performed progressive resistance-training. Both groups performed 3 sets of bilateral leg press and knee extension exercises at 70% 1RM.||The researchers found significant increases in peak power and specific peak power in both training groups but the groups were not dissimilar to each other. However, leg press specific peak power was significantly greater following power training than following progressive resistance-training. Furthermore, total lean leg mass did not change in either group.|
|Henwood et al.||The researchers compared the effects of lower body power-training and progressive resistance-training on measures of muscle function and functional performance in elderly people. The researchers recruited 67 participants aged 65 – 84 years and randomized them to either 24 weeks of twice weekly power training or strength training using 6 exercises.||The researchers found similarly significant improvements in muscle strength in both groups. However, the significant improvements in peak power following power and strength programs were greater in the power group (50.5% versus 33.8%). Additionally, training improved the selected functional tests in both groups in comparison with a non-training control.|
Based on these studies it appears that resistance training is beneficial to older adults by offering positive improvements in muscle size and force characteristics, including peak power, as well as improving measures of physical function and health-related quality of life.
Are combined exercise interventions useful for sarcopenia?
The following studies have explored the beneficial effects of combined aerobic exercise and resistance-training programs in the treatment or prevention of sarcopenia:
|Izquierdo et al.||The researchers investigated the effect of either resistance-training, aerobic exercise or combined training performed twice weekly in 31 elderly men aged 65 – 74 years for 16 weeks.||The researchers reported that both resistance-training only and combined training led to increased muscular hypertrophy and lower body maximal strength with no significant differences between groups. Similarly, the researchers found a significant improvement in maximal workload in the combined and endurance training groups with no differences between groups. Finally, a superior increase was found in arm strength following the resistance training (36%) than the combined (22%) and endurance groups (0%).|
|Foley et al.||The researchers investigated the effect of once weekly or twice weekly high-intensity gym-based program in 21 and 85 older men and women on lower limb strength, balance, gait speed, 30-second chair stand test, timed up and go test, 6-minute walk distance, self-reported pain, activities of daily living, perceived benefits of and barriers to exercise, quality of life and exercise frequency preference.||The researchers found that there was no significant difference in the maintenance of the outcomes after 3 months post rehabilitation between once and twice weekly training. However, in the control group where exercise was not routinely taken part in, the participants did not maintain outcomes to the extent of the intervention groups.|
Based on these studies it appears that combined exercise interventions are efficacious for older adults and have positive outcomes in physical function, quality of life, muscle strength and aerobic capacity.
Do reviews of exercise confirm its usefulness for sarcopenia?
The following reviews have explored the beneficial effects of various types of training for the treatment and prevention of sarcopenia, including aerobic exercise, resistance-training, and combined aerobic exercise and resistance-training programs:
|Liu et al.||The reviewers performed a meta-analysis as part of the Cochrane collaboration group to investigate the effect of progressive resistance training in elderly individuals for improving physical function. The reviewers found 121 trials including 6,700 participants.||The reviewers found that progressive resistance training led to a small but significant increase in physical function (33 trials). The reviewers also found improvements in function limitation, including a modest increase in gait speed (24 trials), and a moderate-to-large effect for getting out of a chair (11 trials). They found that progressive resistance training had a large positive effect on muscle strength (73 trials). Further, the researchers report that individuals with osteoarthritis reported a reduction in pain after progressive resistance training (6 trials).|
|Orr et al.||The reviewers performed a systematic review with analysis to investigate the efficacy of progressive resistance training on balance in healthy community-dwelling, mobility limited, frail cohorts, including 29 studies totalling 2,174 participants.||The reviewers found that 14 studies reported significant improvements in balance. The reviewers note that progressive resistance training was not linked to a certain type of balance – static, dynamic, functional or computerized dynamic posturography. They reported that the inconsistency of balance improvement may be due to differences in cohorts, progressive resistance training programs and methodological flaws. Further, the results may indicate that progressive resistance training alone is a robust intervention for balance, although a multimodal intervention may be optimal.|
|Peterson et al.||The reviewers performed a systematic review and meta-analysis to investigate the effectiveness of resistance training interventions for lean body mass. They also considered the effects of dose and age-range. The analyses included 49 studies totalling 1328 participants.||The reviewers found that resistance training is effective for increasing lean body mass, with a pooled estimate change of 1.1kg. Further, the reviewers noted an association between lean body mass change and volume of resistance training with lesser increases in older adults.|
|Steib et al.||The researchers performed a meta-analysis to investigate the dose response of progressive resistance training in older frail adults.||The reviewers noted that progressive resistance training with higher intensity were superior for increasing maximum strength. Further, they found that power training (lower relative load accelerating the concentric) was superior for increasing muscle power and functional outcomes.|
|Hunter et al.||The reviewers explored the efficacy of resistance training for older adults, noting that the loss of strength and endurance significantly impairs quality of life and the ability to be physically active.||The reviewers noted that resistance training increases strength and muscle mass, as well as improving muscle quality through restructuring of the contractile tissue of the muscle. They observed that resistance training in older adults increases power, reduces the difficulty of performing daily tasks, enhances energy expenditure and body composition and promotes participation in spontaneous physical activity.|
|Ashworth et al.||The reviewers performed a systematic review in collaboration with the Cochrane group to investigate the efficacy of either ‘home-based’ or center-based training programs in older adults. The reviewers included six trials totalling 224 and 148 participants who participated in home and center-based programs. The health outcomes were not concerned with sarcopenia, rather outcomes concerned with cardiovascular disease and chronic obstructive pulmonary disease.||The reviewers found that in the short term, center-based programmes may be better suited for physiological improvements, though in many of the studies the risk of a false positive was high. Further, the researchers conclude that ‘home based’ exercise programs are better adhered to long-term exercise compared to center-based programs.|
Based on these reviews, it appears that resistance training leads to improvements in strength, power, quality of life and ability to perform physical function tasks in older adults. It appears that the success of resistance training programs may be affected by weekly volume, relative load, and repetition speed.
Evidence-based recommendations for exercise
The following guidelines have provided information about what elderly people should do in order to prevent and/or treat sarcopenia:
|Physical activity and public health in older adults: recommendation from the American College of Sports Medicine and the American Heart Association||Overall, the recommended physical activity guidelines for older adults are similar to those of the current guidelines for healthy adults but with some alteration to the intensity of exercise and which types are superior. For aerobic exercise, older adults should perform moderate intensity aerobic activity for >30 minutes, 5 days of the week or vigorous exercise for >20 minutes, 3 days of the week. For resistance-training, older adults should perform at least bi-weekly muscle strengthening activities of 8-10 exercises for 10 – 15 repetitions. Older adults should perform at least bi-weekly flexibility exercises for 10 minutes. Additionally, older adults should participate in more than the minimum guidelines of physical activity, as well as specific balance exercises.|
|Exercise Comes of Age: Rationale and Recommendations for a Geriatric Exercise Prescription||The researchers offer the following evidence-based exercise prescription for optimal ageing and the prevention and treatment of disease in older adults. In respect of resistance training, older adults should train progressively 2 – 3 days per week with 1 – 3 sets of 8 – 10 repetitions at an intensity of 15-17 on the Borg 20-point scale, using a slow speed, with good form and without using the valsalva technique. Additionally, power training strategies are encouraged. In respect of aerobic exercise, older adults should train 3 – 7 days of the week for 20 – 60 minutes per session, with low-impact but weight-bearing exercise, utilising an intensity that represents a 12 – 13 on the Borg 20-point scale. In respect of flexibility, older adults should train 1 – 7 days per week using an exercises that increases the flexibility of all of the major muscle groups. In respect of balance training, older adults should train 1 – 7 days per week, for 1 – 2 sets of 4 – 10 different exercises difficulty.|
Based on these reviews, it appears that a combined program of resistance training, aerobic exercise, balance and flexibility exercises are recommended for older adults, several times per week.
Based on the above review of the literature, the following conclusions can be drawn:
|Prevalence||The prevalence of sarcopenia ranges from 7% to 68% depending on the population studies. Older adults, those living in residential nursing homes following fracture tend to have greater prevalence of sarcopenia.|
|Risk Factors||The risk factors for developing sarcopenia appear to be low physical activity and low body mass index (BMI). Further, functional impairment and low scores on specific functional tests such as the single leg stance time and handgrip strength, are associated with sarcopenia, as is a history of falls.|
|Influences of muscle size/strength||A loss in type II muscle fibre size and muscle fibre number resulting from denervation, decreased skeletal muscle protein synthesis via exercise-induced mRNA signalling, nutritional signalling such as protein ingestion, and oxidative stress’ effect on cellular macromolecules.|
|Aerobic exercise||Aerobic exercise is beneficial for older adults and has positive effects on both aerobic and anaerobic capacity, changes in muscle fiber size and characteristics.|
|Resistance training||Resistance training is beneficial to older adults by offering positive improvements in muscle size and force characteristics, including peak power, as well as improving measures of physical function and quality of life.|
|Combined Exercise||Combined exercise interventions are efficacious for older adults and have positive outcomes in physical function, quality of life, muscle strength and aerobic capacity.|
|Exercise prescription||Older adults should engage in greater than the minimum recommendations of physical activity, including muscle-strengthening, flexibility and balance exercise. Greater volumes of resistance training are advised for skeletal muscle hypertrophy, power and functional performance.|
In summary, the prevalence of sarcopenia in elderly populations can reach 68% and risk factors are low levels of physical activity and low body mass index (BMI). However, a combined program of resistance training, aerobic exercise, balance and flexibility exercises are recommended for older adults to prevent/treat sarcopenia, performed several times per week.
- Iannuzzi-Sucich, M., Prestwood, K. M., & Kenny, A. M. (2002). Prevalence of sarcopenia and predictors of skeletal muscle mass in healthy, older men and women. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 57(12), M772-M777.
- Melton 3rd, L. J., Khosla, S., Crowson, C. S., O’Connor, M. K., O’Fallon, W. M., & Riggs, B. L. (2000). Epidemiology of sarcopenia. Journal of the American Geriatrics Society, 48(6), 625.
- Baumgartner, R. N., Koehler, K. M., Gallagher, D., Romero, L., Heymsfield, S. B., Ross, R. R., … & Lindeman, R. D. (1998). Epidemiology of sarcopenia among the elderly in New Mexico. American journal of epidemiology, 147(8), 755-763.
- Kenny, A. M., Dawson, L., Kleppinger, A., Iannuzzi-Sucich, M., & Judge, J. O. (2003). Prevalence of sarcopenia and predictors of skeletal muscle mass in nonobese women who are long-term users of estrogen-replacement therapy. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 58(5), M436-M440.
- Janssen, I., Heymsfield, S. B., & Ross, R. (2002). Low relative skeletal muscle mass (sarcopenia) in older persons is associated with functional impairment and physical disability. Journal of the American Geriatrics Society, 50(5), 889-896.
- Lau, E. M., Lynn, H. S., Woo, J. W., Kwok, T. C., & Melton, L. J. (2005). Prevalence of and risk factors for sarcopenia in elderly Chinese men and women. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 60(2), 213-216.
- Kim, T. N., Park, M. S., Yang, S. J., Yoo, H. J., Kang, H. J., Song, W., … & Choi, K. M. (2010). Prevalence and Determinant Factors of Sarcopenia in Patients With Type 2 Diabetes The Korean Sarcopenic Obesity Study (KSOS). Diabetes Care, 33(7), 1497-1499.
- Di Monaco, M., Vallero, F., Di Monaco, R., & Tappero, R. (2011). Prevalence of sarcopenia and its association with osteoporosis in 313 older women following a hip fracture. Archives of gerontology and geriatrics, 52(1), 71-74.
- Landi, F., Liperoti, R., Fusco, D., Mastropaolo, S., Quattrociocchi, D., Proia, A., … & Onder, G. (2012). Prevalence and risk factors of sarcopenia among nursing home older residents. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 67(1), 48-55.
- Castillo, E. M., Goodman-Gruen, D., Kritz-Silverstein, D., Morton, D. J., Wingard, D. L., & Barrett-Connor, E. (2003). Sarcopenia in elderly men and women: the Rancho Bernardo study. American journal of preventive medicine, 25(3), 226-231.
- Raguso, C. A., Kyle, U., Kossovsky, M. P., Roynette, C., Paoloni-Giacobino, A., Hans, D., … & Pichard, C. (2006). A 3-year longitudinal study on body composition changes in the elderly: role of physical exercise. Clinical Nutrition, 25(4), 573-580.
- Farnfield, M. M., Breen, L., Carey, K. A., Garnham, A., & Cameron-Smith, D. (2011). Activation of mTOR signalling in young and old human skeletal muscle in response to combined resistance exercise and whey protein ingestion. Applied Physiology, Nutrition, and Metabolism, 37(1), 21-30.
- Lexell, J., Taylor, C. C., & Sjöström, M. (1988). What is the cause of the ageing atrophy?: Total number, size and proportion of different fiber types studied in whole vastus lateralis muscle from 15-to 83-year-old men. Journal of the neurological sciences, 84(2), 275-294.
- Narici, M. V., & Maffulli, N. (2010). Sarcopenia: characteristics, mechanisms and functional significance. British medical bulletin, 95(1), 139-159.
- Arthur, P. G., Grounds, M. D., & Shavlakadze, T. (2008). Oxidative stress as a therapeutic target during muscle wasting: considering the complex interactions. Current Opinion in Clinical Nutrition & Metabolic Care, 11(4), 408-416.
- Coggan, A. R., Spina, R. J., King, D. S., Rogers, M. A., Brown, M., Nemeth, P. M., & Holloszy, J. O. (1992). Skeletal muscle adaptations to endurance training in 60-to 70-yr-old men and women. Journal of Applied Physiology, 72(5), 1780-1786.
- Short, K. R., Vittone, J. L., Bigelow, M. L., Proctor, D. N., & Nair, K. S. (2004). Age and aerobic exercise training effects on whole body and muscle protein metabolism. American Journal of Physiology-Endocrinology And Metabolism, 286(1), E92-E101.
- Harber, M. P., Konopka, A. R., Douglass, M. D., Minchev, K., Kaminsky, L. A., Trappe, T. A., & Trappe, S. (2009). Aerobic exercise training improves whole muscle and single myofiber size and function in older women. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 297(5), R1452-R1459.
- Lepretre, P. M., Vogel, T., Brechat, P. H., Dufour, S., Richard, R., Kaltenbach, G., … & Lonsdorfer, J. (2009). Impact of short‐term aerobic interval training on maximal exercise in sedentary aged subjects. International journal of clinical practice, 63(10), 1472-1478.
- Holviala, J. H., Sallinen, j. M., Kraemer, W. J., Alen, M. J., & Häkkinen, K. K. (2006). Effects of strength training on muscle strength characteristics, functional capabilities, and balance in middle-aged and older women. The Journal of Strength & Conditioning Research, 20(2), 336-344.
- Newton, R. U., Hakkinen, K., Hakkinen, A., McCormick, M., Volek, J., & Kraemer, W. J. (2002). Mixed-methods resistance training increases power and strength of young and older men. Medicine & Science in Sports & Exercise, 34(8), 1367-1375.
- Roth, S. M., Ivey, F. M., Martel, G. F., Lemmer, J. T., Hurlbut, D. E., Siegel, E. L., … & Hurley, B. F. (2001). Muscle size responses to strength training in young and older men and women. Journal of the American Geriatrics Society, 49(11), 1428-1433.
- Bird, M. L., Hill, K., Ball, M. J., & Williams, A. D. (2009). Effects of resistance and flexibility exercise interventions on balance and related measures in older adults. Journal of aging and physical activity, 17(4), 444-454.
- de Vos, N. J., Singh, N. A., Ross, D. A., Stavrinos, T. M., Orr, R., & Fiatarone, S. M. (2008). Effect of power-training intensity on the contribution of force and velocity to peak power in older adults. Journal of aging and physical activity, 16(4), 393.
- Miszko, T. A., Cress, M. E., Slade, J. M., Covey, C. J., Agrawal, S. K., & Doerr, C. E. (2003). Effect of strength and power training on physical function in community-dwelling older adults. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 58(2), M171-M175.
- Bottaro, M., Machado, S. N., Nogueira, W., Scales, R., & Veloso, J. (2007). Effect of high versus low-velocity resistance training on muscular fitness and functional performance in older men. European Journal of Applied Physiology, 99(3), 257-264.
- Henwood, T. R., & Taaffe, D. R. (2005). Improved physical performance in older adults undertaking a short-term programme of high-velocity resistance training. Gerontology, 51(2), 108-115.
- Reid, K. F., Callahan, D. M., Carabello, R. J., Phillips, E. M., Frontera, W. R., & Fielding, R. A. (2008). Lower extremity power training in elderly subjects with mobility limitations: a randomized controlled trial. Aging clinical and experimental research, 20(4), 337.
- Henwood, T. R., Riek, S., & Taaffe, D. R. (2008). Strength versus muscle power-specific resistance training in community-dwelling older adults. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 63(1), 83-91.
- Izquierdo, M., Ibanez, J., Hakkinen, K., Kraemer, W. J., Larrion, J. L., & Gorostiaga, E. M. (2004). Once weekly combined resistance and cardiovascular training in healthy older men. Medicine & Science in Sports & Exercise, 36(3), 435-443.
- Foley, A., Hillier, S., & Barnard, R. (2011). Effectiveness of once-weekly gym-based exercise programmes for older adults post discharge from day rehabilitation: a randomised controlled trial. British Journal of Sports Medicine, 45(12), 978-986.
- Tieland, M., Dirks, M. L., van der Zwaluw, N., Verdijk, L. B., van de Rest, O., de Groot, L. C., & van Loon, L. J. (2012). Protein supplementation increases muscle mass gain during prolonged resistance-type exercise training in frail elderly people: a randomized, double-blind, placebo-controlled trial. Journal of the American Medical Directors Association.`
- Liu, C. J., & Latham, N. K. (2009). Progressive resistance strength training for improvingphysical function in older adults. Cochrane Database Systematic Reviews, 3(3).
- Orr, R., Raymond, J., & Singh, M. F. (2008). Efficacy of progressive resistance training on balance performance in older adults. Sports Medicine, 38(4), 317-343.
- Peterson, M. D., Sen, A., & Gordon, P. M. (2011). Influence of resistance exercise on lean body mass in aging adults: a meta-analysis. Medicine & Science in Sports & Exercise, 43(2), 249.
- Steib, S., Schoene, D., & Pfeifer, K. (2010). Dose-response relationship of resistance training in older adults: a meta-analysis. Medicine & Science in Sports & Exercise, 42(5), 902-914.
- Hunter, G. R., McCarthy, J. P., & Bamman, M. M. (2004). Effects of resistance training on older adults. Sports Medicine, 34(5), 329-348.
- Ashworth, N. L., Chad, K. E., Harrison, E. L., Reeder, B. A., & Marshall, S. C. (2005). Home versus center based physical activity programs in older adults. Cochrane Database Syst Rev, 1
- Nelson, M. E., Rejeski, W. J., Blair, S. N., Duncan, P. W., Judge, J. O., King, A. C., … & Castaneda-Sceppa, C. (2007). Physical activity and public health in older adults: recommendation from the American College of Sports Medicine and the American Heart Association. Medicine & Science in Sports & Exercise, 39(8), 1435.
- Singh, M. A. F. (2002). Exercise comes of age rationale and recommendations for a geriatric exercise prescription. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 57(5), M262-M282.