{"id":18245,"date":"2015-01-24T08:16:16","date_gmt":"2015-01-24T08:16:16","guid":{"rendered":"http:\/\/www.alananna.co.uk\/blog\/?p=18245"},"modified":"2015-01-24T08:16:16","modified_gmt":"2015-01-24T08:16:16","slug":"ramp-test-dxa-scan","status":"publish","type":"post","link":"https:\/\/www.alananna.co.uk\/blog\/2015\/01\/ramp-test-dxa-scan\/","title":{"rendered":"Ramp Test and DXA Scan"},"content":{"rendered":"

As regular readers of this weblog will know, I often volunteer as a participant in various studies at the Sports and Exercise Department at Aberystwyth University.\u00a0Most of these require a fair bit of my time to do but often\u00a0prove interesting and\u00a0painful in equal measure. Interesting from a point of view of getting a measure on my level of fitness at any given time, ‘painful’ thanks to the disgusting supplements<\/a>, horrible exercise regimes – sometimes in heat chambers<\/a> or unusual positions<\/a> – ramp tests,\u00a0regular blood sampling, rectal thermometry and other unpleasantries!<\/p>\n

I’ve recently agreed to participate in a new study which doesn’t sound too bad. The research student is investigating the variations in body composition and bone density during a competitive cyclists season. Earlier research has shown\u00a0that adult male cyclists have lower bone mineral density than age-matched controls.<\/p>\n

All I have to do for this test is lie down on one of the departments more expensive machines, a DXA scanner, so that such parameters can be measured. I also have to do a ramp test. I’m not sure what the results of the ramp test are used for in the study it may just be an ‘incentive’ to get athletes to participate as the test gives them a good measure of their current fitness and can provide data such as VO2<\/sub> Max numbers, Lactate Threshold Heart Rate and Functional Threshold Power – All\u00a0useful tools for working out\u00a0training zones.<\/p>\n

I did the first of my sessions earlier in the week, starting with the DXA scan which\u00a0was interesting.\u00a0I’ve never had one of these before so was keen to see the results. I also did the ramp test which was as hard as usual but not too bad. My results from the ramp test were about average and kind of where I expected them to be. My peak power 363 Watts which was higher than last time when I only hit 348 Wats but nowhere near the maximum I have\u00a0achieved of 395 Watts.\u00a0Vo2<\/sub>Max was right\u00a0where I expected it to be at just over 59ml\/(kg\u00b7min).<\/p>\n

DXA Scanning<\/b><\/h1>\n

Dual-energy X-ray absorptiometry<\/b> (DXA<\/b>, previously DEXA<\/b>) is a means of measuring bone mineral density (BMD) and is typically used to diagnose osteoporosis. The scanner works by firing two X-ray beams with different energy levels at the patient’s bones. This allows\u00a0the BMD to\u00a0be determined from the variation in absorption of each beam.<\/p>\n

Bone Mineral Density\u00a0refers\u00a0to the amount of mineral matter per square centimeter of bones\u00a0and can be used\u00a0as an indirect indicator of osteoporosis and fracture risk.\u00a0Results are often reported in 3 terms:<\/p>\n

    \n
  1. Measured areal density in g\/cm2<\/sup><\/li>\n
  2. Z-score<\/strong>, the number of standard deviations above or below the mean for the patient’s age, sex and ethnicity<\/li>\n
  3. T-score,<\/strong> the number of standard deviations above or below the mean for a healthy 30 year old adult of the same sex and ethnicity as the patient<\/li>\n<\/ol>\n

    T-Scores and Z-Scores<\/h2>\n

    Whilst you might think that the Z-score is one of the more important numbers to look at as this compares your bone density to that of other people of similar age and gender, it’s actually the T-score that is more indicative of problems such as osteoporosis or fracture risk. Bone density tends to peak at around age 30 and then often decreases with age. Although it might be nice to have average or higher than average bone density for\u00a0people of similar age, that isn’t actually much use to you if most people your age are at risk of fractures. It’s more useful to\u00a0compare your bone density to that of peak bone density because at the end of the day the best way to prevent issues such as osteoporosis and fractures is to try to maintain the bone density of a 30 year old.\u00a0The T-score is therefore the relevant measure when screening for problems such as osteoporosis.<\/p>\n