Amidst the nation’s rapidly growing ‘diabesity’ epidemic it is hardly surprising to see clinicians placing significant focus on the metabolically dangerous visceral fat that so easily concentrates around the waistline. But should we also be focusing more on the implications of the decline in lean muscle mass that we know begins after the age of 50?
The term sarcopenia entered our medical vocabulary in 1989 when Irwin Rosenberg (Rosenberg I, Am J Clin Nutr 1989: 1231-3) stated that, ‘there is probably no decline in structure and function more dramatic than the decline of lean body mass or muscle mass over the decades of life.’ Rosenberg coined the Greek term ‘sarcopenia’ (derived from ‘sarx’ for flesh and ‘penia’ for loss) to describe the loss of muscle mass amongst older people, and before long the term had entered the medical mainstream.
In 2010 the European Working Group on Sarcopenia in Older People developed a clinical definition for age-related sarcopenia, along with three consensus diagnostic criteria based on: 1) low muscle mass, 2) low muscle strength, and 3) low physical performance. The diagnosis requires the documentation of criterion 1 plus documentation of either/both of criteria 2 and 3.
(Cruz-Jentoft AF et al Age Ageing 2010: 39 (4) 412-423).
Sarcopenia can be caused by ageing alone or by sedentary lifestyle, bed rest, and certain diseases that involve organ failure, inflammatory disease, malignancy or endocrine disease. Additionally, nutrition can have an impact, with sarcopenia resulting from inadequate dietary intake of energy and/or protein as happens with malabsorption, gastrointestinal disorders or use of medications that cause anorexia.
In other conditions such as malignancy, rheumatoid arthritis and ageing, lean body mass is lost while fat mass may be preserved or even increased. This apparently paradoxical state is known as sarcopenic obesity. Muscle composition change is important when ‘marbling’ or fat infiltrates into muscle, alongside a decrease in fast twitch type 2 muscle fibres, lowers muscle quality work performance.
So, as we age there is a decrease in strength and power, fast strong movements, fine dexterity, endurance of sustained power, acceleration/deceleration of movements and coordination.
Muscle mass and type 2 muscle fibres diminish, central and visceral fat increases, and bone becomes demineralised, leading to osteopenia and osteoporosis. Chronic disease and falls risk increase. There is an associated decrease in motor and sensory neurons and reduced functional capacity and V02 max (the maximum capacity of an individual’s body to transport and use oxygen during incremental exercise).
Taking its measure
Sarcopenia can be measured in different ways. Muscle mass can be measured with CT, MRI, DXA, or more practically in a GP surgery with inexpensive BIA scales (not highly accurate but good for comparison after an intervention). Strength can be measured easily with a grip strength dynamometer and physical performance by gait speed and the so called ‘get up and go’ test. And don’t forget waist measurement for assessing visceral fat.
Progressive resistance training is the best intervention to slow or reverse sarcopenia. Quality of life and function (through strength, endurance and balance training) may be increased at any age as long as the exercise intensity, duration and frequency are sufficient to overload the system without straining them. Changing the load may be necessary for progressive resistance training and working against a heavier load.
All this surely adds up to more than poly pharmacy could possibly achieve and at much less cost for both the individual and the overall health budget. A simple piece of equipment to recommend to a patient for resistance training is a professionally designed yet inexpensive body tube (rubber resistance tubing with handles).
An important message for patients is that as they tone up and gain muscle they may lose fat but not necessarily weight. However losing visceral fat, as well as the fat that can infiltrate muscle, will lead to better metabolic health. In addition there will be major improvements in day to day functioning and quality of life.
The benefits of progressive resistance training:
- Increase in lean muscle mass and hypertrophy
- Fat replaced by lean mass
- Reduction in total and intra-abdominal fat
- Aerobic capacity and V02 max improvement (improved physical fitness)
- Improved joint mobility and flexibility for those with osteoarthritis
- Improved bone density
- Improved gait and gait speed
- Decrease in heart rate and diastolic blood pressure
- Improved insulin resistance
- Less risk of falls