Nick D’Amelio – Exercise Physiologist
Sarcopenia or muscle wasting is described as a loss of muscle mass and consequent muscle strength and function. Whilst some loss of muscle is normal as we age, sarcopenia is important because of it’s harmful health effects. It is now considered an organic disease like that of heart-failure as the health consequences have been shown to become more and more severe if left untreated. It is an independent predictor of falls, disability, loss of independence and increased mortality.
After we hit the age of 30, inactive adults can expect to see a loss of 3-8% of muscle mass per decade. This effect accelerates after age 50 where you can expect to see a 15% loss per decade or have a 45% loss of muscle mass from 20 – 80 years old. To look at opposite ends of the spectrum, a young healthy male may have 35-50kg of muscle whilst an elderly, frail female may have <13kg of muscle.
Once muscle has been lost it is extremely challenging to regain it and therefore preservation of muscle mass in at risk individuals is important. It is often only apparent when a fall or disability has set in at which point a hospital stay with increased bed rest and inactivity makes the problem even worse. For example, one study showed that 68% of patients had worse function after their hospital stay than their pre-hospitalisation level of function.
To be considered to have sarcopenia depends on overall muscle mass and a few strength tests including handgrip, knee extension and chair stand test as well as gait speed. A simple way to know whether you may be at risk is to ask yourself the following questions:
- How is my overall strength? Can I pick up 5kg off the floor?
- Do I require assistance with walking?
- How easy or hard is it for me to get out of a chair?
- How do I go climbing stairs?
- How many falls have I had in the last year?
Losing muscle mass (or catabolism) comes about via inactivity or unloading, inadequate dietary protein and inflammation or oxidative stress. On the other hand, building muscle (or anabolism) requires muscle contraction (exercise), dietary protein, hormones or growth factors. Those who are older, less active and/or with chronic disease will find it even harder to build muscle and therefore require a greater dose of exercise and nutritional interventions to achieve the same results as young healthy individuals who easily respond to muscle building stimulants.
Resistance training advice
Progressive resistance training has been shown to be safe and effective for improving physical function in older adults and a dose-response effect for exercise volume and health benefits has been shown meaning that the more you do the better the results. Things like gardening and occupational physical activity are inadequate for stimulating muscle growth or strength performance and don’t count but have other health benefits. The progressive part is the main recommendation whereby the weight or load increases in difficulty over time.
- 8 to 10 difference large muscle groups including arms, legs and trunk
- High intensity (7-8/10)
- 80% of 1RM (the most you can lift once)
- 3 or more times per week
- 8 to 12 repetitions, 1-3 sets
Muscle mass and strength gains have been shown to increase with higher than average protein intakes in active individuals performing progressive resistance training. Concerns about over consuming protein can be laid to rest as studies show no harm in consuming up to 4.4g/kg/day in healthy individuals. Adequate calcium and vitamin D can also help this process.
- 1.2g to 1.5g per kg body weight per day (e.g. 60kg person aiming for 72-90g/day)
- Equal distribution over three main meals (more muscle building opportunities)
- Aim towards approx. 25g per main meal
- 1,100 – 1,200mg per day
- 10-15 ug per day
A combination of progressive resistance training and adequate protein intake is the most efficient way to increase muscle mass and muscle strength. Whilst it is challenging to reverse, effort should be put into preventing this dramatic loss of function from adulthood onwards and should be emphasised so that as older adults we can live longer, happier and healthier lives.