One of the main markers of how well we age is how well we maintain our muscle mass. Loss of muscle or muscle wastage associated with aging is known as sarcopenia. Unfortunately, as we age, the muscles get smaller in size and the muscle fibers shrink and this is something that will continue to until we die. I’m particularly concerned with this area so I went to see Dr Jarrod Meerkin, the founder of MeasureUp DEXA scanning center. Here’s the excerpt from the interview which you can see on YouTube. Luckily it was all good news, even for those of us with the greatest risk.
What can we do about sarcopenia?
Sarcopenia is easily addressed by physical exercise and it is important to start this as early as possible. Not just any physical exercise though – it needs to be weight-bearing or weight training.
Walking on its own isn’t enough to address sarcopenia. Walking won’t stop muscle wastage, even though it will assist in some maintenance of the muscle tissue.
The key is that as the lean tissue or muscle mass starts to decline with age, there is a point there where we can interrupt that process with some form of progressive overload, such as weight training. Even if you’ve never lifted weights before and you’ve hit 50 or 60, or even 70 years of age, then you’re going to get a wonderful rebound where you’ll be able to actually improve or maintain and increase muscle size and mass.
How does DEXA scanning help us monitor sarcopenia?
DEXA scanning allows us to monitor and manage lean tissue mass. The key is to have a DEXA scan regularly, whether that be once per year, or if you are being aggressive in your pursuit of muscle, every three or six months. Then over time you can get a picture of how well you are maintaining or even building lean muscle mass.
Apparently by the time we get 50 or 55, we are losing a significant amount of muscle mass every year. In particular, the largest muscle group – the gluteal group is the part that decreases most rapidly. And we see evidence of this of course. One of the main complaints from my friends is the sad loss of their bum!
What is a DEXA scan?
A DEXA scan is a very low-energy x-ray. It divides the body into muscle tissue, fat tissue and bone tissue. It gives a three-compartment model of the body composition and accurately measures fat mass, lean mass, and bone mass down to one-tenth of a gram.
Are there ideal DEXA scan measurements?
There are some ideal measurements and these have been identified over the last ten years of Jarrod’s research work as well as from the work he’s done in the clinic. For most women, if we are sitting around 35 to 45 kilos of lean tissue, then we are doing really well. For most males, if they’re around anywhere from 50 to 70 kilos of lean tissue, they’re also doing very well.
Rather than take a group approach though, it is better to evaluate our own results over a period of time. Once we get an initial scan we can then follow our own progress across the years and take a longitudinal approach to monitoring not only our fat mass but also our lean tissue mass. The muscle aspect – the lean tissue aspect – is actually more important than the fat side in many instances because it’s the muscle tissue that helps with fall prevention. Muscle allows us to maintain balance. It also allows us to pick up our grandkids and be active and do lots of different things well and truly into our 60’s or 70’s and hopefully 80’s and 90’s.
Are there any side effects or risks with DEXA?
In terms of evaluating risk for a radiological or any other procedure involving ionizing radiation, we can use the ALARA principle, which is the acronym for “as low as (is) reasonably achievable”. So using that principle, Jarrod encourages a break of at least three or four months between scans.
The radiation from a DEXA scan is typically very low at 1 to 4 microseiverts. To put it into perspective we receive 10 microseiverts on a one hour flight, say a Sydney to Melbourne flight. We’d receive the equivalent of a chest x-ray from Sydney to Los Angeles which is about 40 to 50 microseiverts. So it appears that DEXA is very low and very safe.
DEXA scanning for bone health
The DEXA’s primary use has been to examine bone health and bone density. In Australia, the government uses an item code 12323 to allow every Australian a free bone density scan over the age of 70, as a way of screening for osteoporosis. MeaureUp see around 50,000 people per year and approximately 25% have osteoporosis, 25% are normal and 50% have osteopenia. So, osteopenia and osteoporosis are very prevalent and the DEXA is the tool that is used the most to diagnose chronic long-term diseases such as low bone density or osteopenia and osteopororosis.
What is osteopenia?
Ostopenia is the techical term for low bone density and is determined by looking at what is known as the T-score of our bone density result. If our bone density falls below -1.5, then we are considered to be osteopenic.
It’s better to know whether we are osteopenic earlier rather than later and getting tested anywhere from the onset of menopause and onward is ideal. Whether we are at risk of osteopenia is determined largely by genetic and environmental factors, but we have the opportunity to combat risk and maintain our bone density and bone mass through physical activity and diet.
Menopause and bone density
Reproductive hormonal changes that occur at menopause, particularly around estrogen will have an impact upon bone density and the ability of our body to maintain bone mineral density and bone mass.
What is a healthy body composition?
A healthy body composition involves a number of parameters. When it comes to bone, anything from around 1 gram of bone per 1 cm2 for the lumbar spine or the proximal femur, means we are doing very well. For muscle mass, women (and this is also dependent upon hAeight), then ideally we have 35 to 45 kilos of lean tissue and anywhere from 15 to 25 kilos of fat tissue. For males, there should be a similarl bone density, 1 gm per cm2, 50 to 70 kilos of lean tissue and anywhere from 10 to 20 kilos of fat tissue.
It’s better not to look at body-fat percentage as we need to compare our progress to ourselves and not to others. Also BMI or body mass index is often used to determine how healthy we are and this has been perpetuated as it is a simple index, to try and categorize people whether they’re healthy or unhealthy. It was designed for epidemiological research. It wasn’t designed to be used on the individual because it doesn’t take our lean tissue mass into consideration. Rugby League players, for example, are large males with a lot of muscle mass and if this measure is used then they would be deemed overweight or even obese. So, it’s very important that we use a tool that allows us to take muscle into consideration
which is what DEXA can do.
DEXA scanning as an indicator of how well we are aging
We can use our DEXA result over time to see whether our muscle mass is increasing or decreasing. If it’s increasing, this indicates our training is good and our diets are right for us. But if it’s just being maintained or perhaps even slightly decreasing and we think we’ve got our training right, then it could be that we may require protein supplementation if we are not getting an adequate amount of protein through normal food intake.
On the note of supplementation, if we eat 150 grams of protein a day with no weight training or no physical activity, this won’t mean that we are going to be able to lay down lean tissue. This requires an exercise stimulus. So by monitoring our lean tissue mass, then we are more likely to know when we have enough.
Last reviewed 04-Nov-2016
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