Snakes and ladders

I recently devised a test of cardiac fitness based on the relationship between heart rate and power output on the elliptical cross trainer. At home we have a Tunturi C6 elliptical, which I had bought as a present for my wife almost 4 years ago, at a time when she had expressed an interest in getting fit. After about three sessions on the Tunturi, she took up cycling to work and has continued to do so ever since. So the Tunturi achieved its purpose, but not quite not in the way intended. For the past four years it has mainly stood un-used in the guest bedroom. From time to time I use it myself, though I find it far less interesting than running in the country-side.

However, it does come fitted with a power meter and heart monitor so it offers the possibility of a test of fitness that is independent of the weather and the bogginess of the woodland or riverside paths.

My recently devised test consists of consecutive 2-minute epochs at 160 steps minute with six step-wise increases in resistance such that power output increases in steps spanning the range 30 watts to 230 watts. I record average heart rate in the final 15 seconds of each 2 minute epoch At my present level of fitness, my heart rate when generating an output of 30 watts is around 90 and rises in a straight line to around 145 at 230 watts. It should be noted that my actual rate of energy consumption is much greater than indicated by the power meter. Comparing the power meter reading with the estimated energy consumption (in Kcals/min) demonstrates that for a 63 Kg person, about 83% of the energy consumed is spent overcoming internal friction in muscles, ligaments and joints, and ends up generating body heat. The rate at which the sweat pours off me confirms that a large proportion of the energy is spent heating the body.

The attached chart shows the graph of heart rate v. power output on 17th November (filled diamonds), before I commenced my recent back-to-back moderate intensity training sessions; and two weeks later on 30th November (open diamonds) when my fitness had improved quite noticeably. HR was about 10 bpm lower than on 17th November across the entire aerobic range. I tested myself again today before my run. The open triangles indicate today’s HR readings and demonstrate that my recent bout of flu has taken me back to a level of fitness only marginally better than on 15 November. In this game of snakes and ladders, fitness is gained with great effort and lost very easily.

hrvpowerdec2008

After the fitness test on the elliptical I went for easy 10K run in the woods. The woodland floor is still thickly carpeted in leaves, mainly the rich brown of beech and somewhat more sombre brown of oak, but to my surprise, green shoots that look like sprouting bluebells were pushing their way through the leaf cover. Maybe they were snowdrops, which are more likely in December, but they looked like bluebells – so even though this winter has so far been chillier than recent winters, it appears that global warming is causing confusion among the woodland flowers. I did not have my camera with me, but I have pasted a photo which I took at the beginning of May 2008, in the header of my blog. Maybe in 2009 we will have scenes like this before mid-April.

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2 Responses to “Snakes and ladders”

  1. Andrew(AJH) Says:

    A beautiful addition to the blog header, and a beautiful place to run!

  2. Ewen Says:

    That looks an inviting path to run down!

    I’ve been thinking about easily lost fitness gains lately, with a light week just past, the HR is a little higher than normal, even accounting for the hot days we’ve been having.

    Thanks for your comments on my year. I might post on the subject, but I’ve never been a great ‘taperer’ for races. That comes from many times ‘resting up’ and racing poorly. I think my big failure was not absorbing the training well – something to address in ’09 🙂

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