“Physiologically you’re capable”
So the test results are in. A month ago I did a body composition, VO2max and threshold test with my friend Anne Delextrat at her university. She offered to do two tests for me, one before the bulk of my training for the Berlin Half Marathon and another after the race. We’ll compare and contrast the findings and Anne will use the information to give me tips on what to focus my training on to improve strength, speed and endurance. Here is the first set of results and some thoughts on what to use them for.
Test 1. The body composition test calculates the proportions of muscle, bone, etc. that your body that is made up of by sending electric impulses through your body. Anne had warned me not to eat or drink a couple of hours before and to make sure I had gone to the toilet (sorry for the TMI, it’s important!) to make sure that the machine would make correct calculations. Water is processed by the machine as lean mass, i.e. muscle, and could skew the results.
Bone mineral density measures ‘the amount of mineral matter per square centimeter of bones’. Exercise builds the density of your bones, and in age it reduces the normal rate of ‘bone mass loss’, which we all face. There is a statistical relationship between lower bone density and bone fractures and particularly for girls and women the higher risk of osteoporosis means that women should ensure that they get enough exercise and that their diet is rich on calcium and contains sufficient calories. I’m really pleased that my figures came in at above average - I can now tell my mom to not worry so much about me getting osteoporosis!
Intriguingly, the muscle measurements were per limb. Both my legs and arms are well above the average, whereas my trunk is a bit under. Anne said that this is often the case with female runners and that core exercises to strengthen those muscles could help my performance.
My test revealed that I have a fat percentage of 22% of my overall body weight. This is a fairly decent amount for a female, non-elite athlete, and I’m actually quite intrigued to know what the comparative results will show, post-race (and post-all-that-training).
Test 2. The lactate threshold measures the point at which the lactate acid produced during exercise begins accumulating in your blood stream. It’s not the same as your anaerobic threshold - when your body switches over to anaerobic processes to fuel your movements - but they very often occur around the same time.
Basically the mad scientist attached a mask to my face, hooked it up and sent me onto the treadmill. She fitted me with a heart rate monitor too, to double check my levels of exertion. Increasing the speed of the treadmill in 1km/hr increments per four minutes with 1 minute rests, we soon had a graph showing my oxygen intake (red) and carbon dioxide emission (blue) on screen:
Between sets Anne pricked my finger to take a drop of blood, measuring the lactate content in my blood. We stopped after more than 25 minutes on the dreadmill. Using the blood values, she drew up a graph identifying the point when lactate levels went from steady to a sharp incline, indicating my lactate threshold. This happened somewhere between 12.5-13km/h, which is just faster than the pace I normally settle at on a run.
Test 3. The VO2max test measures your oxygen consumption to identify the maximum amount of oxygen that your body can process (your aerobic performance). Your VO2max is measured when your oxygen consumption flattens out despite increase in exertion levels. The volume of oxygen is related to your weight to adjust for difference in lung size, difference in body sizes, and is output in mL/kg/min. Endurance athletes (runners, cross country skiers, etc) will have much higher values than sprinters, who rely on anaerobic processes for their bursts of effort.
Again, up on the treadmill with mask on and this time the challenge was the incline. I would run two minutes and then Anne increased the incline 2% for the next two minutes’ run, and so on. 6x 2mins later I was lying exhausted on the treadmill trying to catch my breath, feeling more than spent. This was probably my least favourite test, not just because it was HARD, but because with instructions to run till you can’t any more there’s a hard mental game going on. You can always go a bit further if you will yourself, right? So it’s really both how much your body can actually do versus what your mind thinks it can.
Following the run Anne took a final blood sample, again testing my lactate levels. This time it was to make sure I had pushed hard enough to reach my max. She also checked that my heart rate exceeded 90% of my theoretical maximum, and finally that my respiratory exchange ratio (CO2 emission divided by oxygen consumption) was over 1.15. Normally you would emit less or the same amount of CO2 as you consume oxygen, but when your lactate levels increase, your body breaks it down into CO2, which means that you emit more CO2 than you consume oxygen. The graph below on the left shows the blue CO2 rising well above the red O2:
I passed all these three control checks, and after some calculating, Anne told me that my VO2max result is 54mL/kg/min, which just about falls within the ‘athlete’ values for a female runner of my age.
The result of my hard work was this: a) I had a pin cushion for a finger and b) Anne calculate a projected time for my upcoming half marathon to be somewhere between 1h40 and 1h45. “This is the time you are physiologically capable of” she said, i.e. this is what my body can perform if my mind doesn’t hold it back. What’s rather exciting about this is that my race time was 1h42m41s - basically right where she predicted!
A major caveat is that the test was done 6 weeks before the race, and that my training (or in this instance lack of) could have influenced the results either way.
I improved my PB by nearly 5 minutes in this race and proved to myself that with hard work there is a lot of potential improvement ahead. It’ll be interesting to see what the second test reveals about my development over the two months between tests. Who knows, maybe I’m already capable of more than I think?
A massive thank you to Anne for offering to do these tests and for checking over this post to make sure I didn’t talk rubbish! More to follow.
