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Prove for certain you’re making a difference

School Of Personal Training Posted Mar 12, 2015 Future Fit Training

Your success as a personal trainer rests squarely on your clients’ tangible results. The accuracy which these are measured reflects how successful you are.

Prove for certain you’re making a difference

And if you’re any good at what you do that should primarily mean reducing their body fat and/or increasing their lean muscle mass – both absolutely and as a percentage of total body mass.

Unfortunately, the most accessible and lowest cost (and therefore popular) methods of measuring body composition are also the most unreliable and imprecise.

At the very back of the pack and ineligible for consideration are weighing scales (and their fraudulent offshoot, BMI). Scales tell you nothing more than your relationship with gravity, so unless your client is a jockey or a boxer, scales should play no part in your armoury.

Skinfold calipers are cheap, prevalent and have their place in measuring body changes but, like a gun, in untrained hands they can be dangerous. In Sports Nutrition for Paralympic Athletes, editor Elizabeth Broad quotes studies that state, “…highly skilled technicians are required if reliable data are to be collected. Technicians need to be meticulous in terms of both accurate site location and measurement technique. Measurements just 1-2cm away from a defined site can produce significant differences in results…”

Another technique for measuring body fat is bio-electrical impedance analysis (BIA), whose form factors range from £50 scales you can buy in a department store to £13,000 devices that resemble airline self-check-in kiosks. 

Whatever the cost, the technology (which actually measures electrical resistance to make a guess about body water to, in turn, make a guess about fat) is the same. The variation in price range is only matched by the variability of the results – drink a litre of water and the device will record lower body fat. Or if you’re not thirsty, simply flick the switch on many BIA devices to the ‘athlete’ setting. Lean at the flick of a switch! Tempting but hardly scientific.

The most accurate way of measuring body composition and now universally regarded as the gold standard is dual-energy X-ray absorptiometry, or DEXA.

As the name suggests, DEXA produces X-ray photons of two different energy levels. Bone and soft tissue weaken the X-rays at different rates. The unique composition of bone, fat and lean (non-fat soft tissue) mass enables each of these to be separately and precisely analysed.


As well as accuracy, DEXA automatically provides regional data and imagery for arms, legs and trunk and can give a very good estimate of visceral fat – the ‘bad’ fat that surrounds the internal organs and is linked to heart disease, diabetes and even cancer.

As you’ve probably guessed by now, you can’t buy a DEXA scanner in John Lewis. DEXA is a medical-grade piece of equipment that your clients have to travel to and that will cost them £100 or more.

But the accuracy, precision, depth and breadth of body composition data makes it essential for baseline and quarter-to-half-yearly measurement. In Australia, Canada and the US, where DEXA is well established, it’s common practice for PTs to insist on a DEXA scan before signing up a new client.

DEXA gives you research-quality information that adds to your credibility, motivates your clients and differentiates you in what is undeniably an overcrowded industry.

A mediocre PT will fear DEXA because it doesn’t discriminate. Unlike calipers and BIA, you can’t squeeze it harder or flick the ‘athlete’ switch to fudge the result.  (Indeed, a DEXA scanner has to be calibrated every day with unique ‘phantoms’ of known composition; if the scanner doesn’t record the actual density within a tiny margin of error it immobilizes itself.)

A PT who values accuracy, veracity and professionalism will embrace DEXA, as it has been embraced by sports science research labs, elite training centres and professional teams such as Chelsea, Arsenal and West Ham football clubs, and England Rugby.

Take a look at this article in Cyclist magazine for more details.

Fortunately, DEXA is now more accessible than it has been, through companies such as Bodyscan (bodyscanuk.com), which has facilities in London, Manchester and East Anglia. Clients book online, receive an immediate printed report with detailed notes and an optional consultation that helps turn the data into usable information. Bodyscan also pays PTs a referral fee every time your clients make a booking.

So, accuracy, differentiation and revenue. What’s not to like?!

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