Muscle Function: Effects of Aging

 

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Introduction[edit | edit source]

As we age our muscles undergo progressive changes, primarily involving loss of muscle mass and strength.

The age-related loss of muscle function is known as Sarcopenia[1], derived from the Greek words for flesh (sarcos) and loss (penia) and its definition includes loss of muscle strength and power, as well as reduced function[2]. It occurs with increasing age, and is a major component in the development of frailty.

The loss of muscle mass during the aging process is important clinically as it reduces strength and exercise capacity, both which are needed to perform activities of daily living.

Age-related changes in muscle structure[edit | edit source]

With increasing age, we lose muscle mass: lean muscle mass contributes up to 50% of total body weight in young adults, but this decreases to 25% by 75 to 80 years[3]. 
Typical muscle changes with age:

Gross Muscle changes:[edit | edit source]

  • Reduced muscle mass (replaced by increased fat mass)
  • Reduced muscle strength
  • Slowing on contractile properties and rate of force development

Muscle Fibre changes:[edit | edit source]

  • Atrophy
  • Fibre necrosis
  • Fibre type regrouping

Effects of endocrine changes on muscle[edit | edit source]

With increased age, the following changes in endocrine function result in sarcopenia:

  • Increased insulin resistance
  • Decreased growth hormone[4]
  • Reduction in oestrogen and testosterone[5]
  • Vitamin D deficiency[6]
  • Increased parathyroid hormone[7]

Conditions associated with impairment of skeletal function[edit | edit source]

Physiotherapy Interventions to minimise or reverse sarcopenia[edit | edit source]

Resistance exercise training :[edit | edit source]

The effects of resisted exercise on ageing muscles is the same as for young muscles:

  • improved muscle strength
  • increased muscle power - power is a product of both strength and speed. Optimal power reflects how quickly you can exert force to produce the desired movement
  • improved muscle composition

Evidence:[edit | edit source]

Resistance or weight training has been demonstrated to produce increases in muscle strength and power, and also mobility function, in older people living in the following settings:

  1. independently in the community[8],[9],[10]
  2. in nursing homes[11],[12],[13]
  3. hospitalised elderly people[14],[15],[16]

References[edit | edit source]

References will automatically be added here, see adding references tutorial.

  1. ↑ Rosenberg IH: Sarcopenia: origins and clinical relevance. J Nutr 127:990S-991S, 1997
  2. ↑ Rolland Y, Czerwinski S, Abellan Van Kan G, et al: Sarcopenia: its assessment, etiology, pathogenesis, consequences and future perspectives. J Nutr Health Aging 12:433-450, 200
  3. ↑ Short KR, Nair KS: The effect of age on protein metabolism. Curr Opin Clin Nutr Metab Care 3:39-44, 2000
  4. ↑ Toogood AA: Growth hormone (GH) status and body composition in normal ageing and in elderly adults with GH deficiency. Horm Res 60:105-111, 2003
  5. ↑ Gower BA, Nyman L: Associations among oral estrogen use, free testosterone concentration, and lean body mass among postmenopausal women. J Clin Endocrinol Metab 85:4476-4480, 200
  6. ↑ Wicherts IS, van Schoor NM, Boeke AJ, et al: Vitamin D status predicts physical performance and its decline in older persons. J Clin Endocrinol Metab 92:2058-2065, 200
  7. ↑ Visser M, Deeg DJ, Lips P: Low vitamin D and high parathyroid hormone levels as determinants of loss of muscle strength and muscle mass (sarcopenia): the Longitudinal Aging Study Amsterdam. J Clin Endocrinol Metab 88:5766-5772, 200
  8. ↑ Beneka A, Malliou P, Fatouros I, et al: Resistance training effects on muscular strength of elderly are related to intensity and gender. J Sci Med Sport 8:274-283, 2005
  9. ↑ Henwood TR, Riek S, Taaffe DR: Strength versus muscle power-specific resistance training in community-dwelling older adults. J Gerontol A Biol Sci Med Sci 63:83-91, 2008
  10. ↑ Taaffe DR, Duret C, Wheeler S, et al: Once-weekly resistance exercise improves muscle strength and neuromuscular performance in older adults. J Am Geriatr Soc 47:1208-1214, 1999
  11. ↑ Beyer N, Simonsen L, Bulow J, et al: Old women with a recent fall history show improved muscle strength and function sustained for six months after finishing training. Aging Clin Exp Res 19:300-309, 2007
  12. ↑ Beyer N, Simonsen L, Bulow J, et al: Old women with a recent fall history show improved muscle strength and function sustained for six months after finishing training. Aging Clin Exp Res 19:300-309, 2007
  13. ↑ Harridge SD, Kryger A, Stensgaard A: Knee extensor strength, activation, and size in very elderly people following strength training. Muscle Nerve 22:831-839, 1999
  14. ↑ Hauer K, Specht N, Schuler M, et al: Intensive physical training in geriatric patients after severe falls and hip surgery. Age Ageing 31:49-57, 2002
  15. ↑ Suetta C, Magnusson SP, Rosted A, et al: Resistance training in the early postoperative phase reduces hospitalization and leads to muscle hypertrophy in elderly hip surgery patients—a controlled, randomized study. J Am Geriatr Soc 52:2016-2022, 2004
  16. ↑ Sullivan DH, Roberson PK, Johnson LE, et al: Effects of muscle strength training and testosterone in frail elderly males. Med Sci Sports Exerc 37:1664-1672, 2005
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