VITRUVIAN EXERCISE PHYSIOLOGY
News & Information
SARCOPENIA
What is Sarcopenia?
Sarcopenia is an age associated loss of muscle mass, strength, and function. Clinically, it is defined as a loss of muscle mass coupled with functional deterioration (i.e. loss of walking speed, walking distance and grip strength). It can begin as early as the 4th or 5th decade of life and is a major contributor to poor health and disability in older adults. Assessments and further information surrounding frailty in older adults can be found here: Frailty and disability
Our muscles are made up of many individual muscle fibres bundled together. In sarcopenia, both the number and size of these individual fibres decrease. There is also a corresponding reduction in the quality of muscle fibres. This occurs through mechanisms that alter the biology of the muscle, including metabolic, cellular, vascular, and inflammatory changes.
What contributes to the development
of Sarcopenia?
Main Underpinning
Physiological Mechanisms
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A lack of appropriate physical activity (in particular loaded activity and resistance exercise)
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Age related hormonal changes (a decrease in hormones that regulate muscle growth)
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Negative energy balance through inadequate nutrition (particularly reduced protein intake)
Biology of Sarcopenia
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Decreased number of motor units (these are the areas where our nerves meet our muscles and tell them to work)
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Fat infiltration within and between muscle fibres (resulting in decreased overall strength and function)
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Increased oxidative stress and chronic inflammation → redistribution of fat → increased risk of obesity
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Decreased cellular repair and mitochondrial quality (these are the engines of the cells)
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Decreased capillarisation (decreased blood flow)
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Insulin resistance (affecting blood glucose control and a risk factor for diabetes)
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Decreased mTOR (a natural substance involved in protein synthesis)
The causes of sarcopenia are multifactorial, with the main mechanisms listed above. Older adults who are less physically active are more likely to have lower skeletal muscle mass and strength and have an increased risk of developing sarcopenia. A more sedentary lifestyle is associated with poor functional performance and early disability.
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Appropriate physical activity and exercise has a positive effect on ALL of the above biological changes.
Health and Lifestyle Conditions
Associated with Sarcopenia
Sarcopenia is associated with a diverse group of health conditions, including;
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Risk of falls and fractures
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Loss of physical independence
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Cognitive decline and depression
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Type 2 diabetes
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Cardiovascular disease
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Compromised immune function
What can be done?
Like all cells in the body, our muscle tissue is adaptable to the demands we place on it. It can be in an anabolic state (building up) or a catabolic state (breaking down). Resistance training and consuming sufficient protein are the primary recommended strategies to promote an anabolic state within our muscle tissues.
“At present, resistance exercise and appropriate protein intake have been established as the primary form of treatment for sarcopenia.”
Performing resistance training and achieving appropriate nutritional intake will not turn you into a body builder. We are referring to maintaining adequate levels of muscle mass required to perform activities of daily living comfortably, well into older age.
Role of Physical Activity and Exercise
Regular exercise throughout the lifespan reduces the severity of sarcopenia and its associated comorbidities. In fact, current evidence suggests that appropriate resistance training can reverse the progression of sarcopenia. The addition of power training has been shown to provide even greater improvements to functional outcomes compared to traditional resistance training alone in older populations. Power training can be performed in a variety of ways, a simple example would be slowly sitting down to a seat, before standing up as fast as possible.
"Skeletal muscle displays features of plasticity, enabling growth over the life course in response to the stimulus of physical activity"
An exercise program to combat sarcopenia should be individualised to suit current circumstances, including health and medical status, functional ability, contraindications, and personal objectives. For those with, or wishing to prevent sarcopenia, it is recommended that a resistance training program include:
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At least 3 sessions/week
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Exercises incorporating all the major muscle groups
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Loads sufficient enough to elicit a strength response
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Incorporating elements of power training
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Incremental progression, as tolerated
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Supervision by a professional
Role of Nutrition
Current evidence suggests that the benefits of resistance exercise can be augmented by the addition of sufficient protein intake, with protein supplementation if required.
“Older adults in the highest quintile of protein intake lost significantly less muscle mass than those in the lowest quintile of protein intake”
The below table outlines the recommendations from a recent 2022 review, summarising research based primarily on individuals over 60 years of age.
Protein Intake Daily Recommendations
Population
Guildelines Protein
Example: 70kg Individual
Older Adults – For general health
1.0 – 1.5g/kg/day
70 – 105g/day
Older Adults – Completing structured exercise, aiming to maximise muscle anabolism
1.6 – 2.2g/kg/day
112 – 154g/day
Additional nutritional strategies supported by the evidence base to mitigate the risk of sarcopenia include;
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maintaining energy balance (energy intake = energy output)
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creatine monohydrate supplementation
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avoiding Vitamin D deficiency (supplementation may be useful in some cases)
The Vitruvian Team.
Age-related muscle anabolic resistance: Inevitable or preventable? Aragon, A.A. et al. Nutrition Reviews. 2022.
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A Multifactorial Approach for Sarcopenia Assessment: A Literature Review. Supriya et al. Response and Adaptation during Human Exercise: From Physiology, Metabolism and Musculoskeletal Modelling to Understand Functional Disorders. 2021.
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Role of exercise in age-related sarcopenia. Yoo et al. Journal of Exercise Rehabilitation. 2018.
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Comparison of power training vs traditional strength training on physical function in older adults. Balachandran, A.T et al. JAMA Network Open. 2022.
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Effects of a targeted multimodal exercise program incorporating high-speed power training on falls and fracture risk factors in older adults: A community-based randomized controlled trial. Gianoudis, J. et al. Journal of Bone and Mineral Research. 2013.
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The decline in skeletal muscle mass with aging is mainly attributed to a reduction in type II muscle fiber size. Nilwik, R. et al. Experimental Gerontology. 2013.
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World Health Organisation. The Health, Ageing, and Body Composition Study. 2023
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