As I recover from a frozen shoulder I’ve been working on building up my fitness, primarily on the bike trainer.  It’s easier to pedal a bike than run or swim, and it’s the fastest way I know to get fit without risk of injury.  I’ve started doing my indoor sessions on a Wattbike.  This is a fantastic tool for getting real information about the power I’m generating in my legs.  The bike gives you separate right and left leg power, and you can compare the power generated to your heart rate, providing all sorts of insight into your fitness.  You can also see a graph of your pedal stroke, enabling you to work on improving your pedalling technique.

The first test I’ve done has been to measure my FTP (Functional Threshold Power).  This is the amount of power I would typically generate over the course of a 1 hour race, with nothing left on the table.  Knowing this number gives 2 things – I can use it to measure progress, and I can figure out my optimal training zones.

Since I wasn’t used to the Wattbike (it’s a much smoother ride, and the air resistance it very different to the turbo) it took me a couple of attempts to pace the test, but the end result seems about right.  My power is about 223 according to Strava.  At my peak, before injury, I was around 260.  I suspect the Wattbike is measuring higher than the estimates I got from Strava on the turbo, but  50 watts feels about right – I can believe that’s where I am at relative to the start of the year.   You might spot that this isn’t actually a full hour on the bike – it’s 30 minutes (after a warm-up which isn’t shown).  Joe Friel reckons in his ‘Power Meter Handbook‘ that a turbo session indoors is roughly equivalent to a 1 hour race outdoors – and if that means I only have to suffer through this gruelling test for 30 minutes, I’m in ;)  This is undoubtedly the toughest indoor ride I do – you need quite a bit of mental strength to hold on for the full duration – and I’m actually making it harder these days by going all out for a full 30 minutes.  You can see that nice steady climb in heart rate, right up to my max.  The Wattbike manual has alternative, less stressful ‘progress’ checking tests, which I will definitely try.

There’s a strange drop of speed on the graph; I didn’t actually stop – and the power/cadence values are constant, so hopefully that’s just a glitch.

The next test I want to do is a Zone 2 constant heart rate test, to get a baseline aerobic efficiency.  I’m also going to add a pedalling technique session to try to improve my power output over the whole pedal stroke.  Mostly, I’m going to continue with my program of interval sessions to build up my fitness/power as fast as I can.  My target is 300 watts by this time next year, in time for Ironman Barcelona….  I’ll post about future tests when I’ve done them.

FTP Test

Strava Data for FTP Test.



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Nanovg is a nice little vector 2D rendering library.  I wrote a D3D11 backend for it a while back – you can get in from my fork on github, and it is now up to date with the latest upstream code.


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I had a brief dalliance with Lisp earlier in the year, and finally got around to cleaning up and putting my little Scheme Interpreter on Github this weekend.  Writing a lisp interpreter was always on my ‘programming bucket list’.  It was fun to do, and probably entirely useless.  The best kind of programming exercise Smile

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