Two by Twenty - Take 2

Way back I posted about a workout known as the 2 x 20. It's pretty simple. Ride for 20-minutes at around your time trial pace/effort/power, have a short break and then do it again. Combined with a warm up and cool down, it makes for a nice tight one-hour workout that's exceptionally effective at developing one's aerobic engine.

On a power meter chart - it looks a bit like this:


The squiggly yellow line denotes power output and was around 200 watts for two efforts lasting around 20-minutes. The horizontal dashed line shows 200 watts.

In between efforts I stopped and hopped off the ergo bike to remove my leg and dry the liner and leg, and replace so I could go again. It's a challenge I face at the moment as the leg liner tends to fill with perspiration making it a little weird to pedal. Imagine pedalling in loose gumboots with water in the bottom of them.

Of course there is nothing magical about 20-minutes. Overall it's about getting enough time at these levels. Some do 3 x 20-min. Others 3 x 15-min. Some ride the hour straight at that power. Typically though we break up efforts into smaller duration "chunks" (known as intervals) so that we can maintain perhaps slightly higher power than we may otherwise have the motivation to do all in one go.

So what's actually happening when I train at this level? Well lots of good things. The main physiological changes that are brought about by riding at these intensities include:

- increasing my muscle glycogen storage capacity. Glycogen, along with free fatty acids are key sources of chemical energy which is converted by our muscles into mechanical energy (and heat). Basically this means I develop the ability to ride hard for longer.

- increasing muscle mitochondral enzymes - these are the "mini power plants" inside our muscles, which use the available oxygen for the conversion of chemical energy to mechanical energy (as well as heat). The greater the number and density of these suckers we have the better

- increased lactate threshold - which is another way of saying one can go harder for longer. Blood lactate concentration is one way of determining how effectively our working muscles are performing at various intensities.

Now you gain these benefits by riding at lower intensity levels as well but the rate at which improvements occur is greatest at these intensities, which is an effort level equivalent to how hard you could maximally sustain riding for about an hour.

They are also effective at increasing my blood plasma volume, increasing my heart stroke volume (amount of blood moved per beat) and maximal cardiac output (maximum amount of blood I can pump per unit time) and for increasing the amount of oxygen I am capable of both delivering to my working muscles and actually utilising (my VO2 Max).

There are other funky things too, like increasing the density of blood carrying capilliaries inside the muscles - which enables a greater and faster transfer of oxygen to the working cells. On top of that, our (slow twitch) muscles fibres also grow.

The body is an amazing thing. It knows how to adapt when it is provided with a training stimulus. The trick is to keep providing that stimulus in the right doses.

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Birthday Bash

It's my birthday today!

So what does any self respecting bike rider do on his birthday? Race of course!!

Last week I reported on my effort at a local criterium race, which did me in before 10 minutes had passed. This time it wasn't so bad and I lasted 30 minutes before withdrawing gracefully.

I had a lap out for "leg mechanical" and then rejoined for a lap but lost my momentum and decided I'd had enough and had done what I'd set out to do (which was to show I can get around OK in a race). It's a bit tricky with the leg, the liner I use fills up with (yuk - wait for it) sweat and it gets a bit squishy to pedal when it's like that. The liner also tends to slip down the leg a bit. So I pulled off to the car quickly to remove the leg and liner, dry them off and put them back on again. It's probably not technically a mechanical but I don't think the race officials are too worried!


Here is the race file with 30-second smoothing.


Heffron Crit D Grade:
Duration: 32:30 (34:56)
Work: 354 kJ
TSS: 57.9 (intensity factor 1.035)
Norm Power: 207
Distance: 18.457 km
Min Max Avg
Power: 0 747 182 watts
Speed: 3.7 45.9 34.1 kph

With my warm up / cool down, that was a 97 TSS day and so that was plenty. I was a little stiff 'n' sore from last week's race, so no doubt I'll feel this one as well in the coming days. But as they say, the more you train, the more you can train.

Proof is in the pudding, so to speak. Here is my training since 13 June:


My chronic training load is just a touch shy of 30 TSS/day.

I also did a MAP Test during the week. 289 watts. That's about 70% of my prior accident MAP level. I'm also ~ 20% heavier at the moment, so on a power to weight basis, I am classed as "untrained".

I upgraded my crank length twice this week. I tried a 165mm left crank arm earlier in the week, and yesterday I did an easy spin on the ergo with a 170mm crank. That was OK once I'd lengthened my leg a bit, so I put that crank on the race bike and that's what I rode today.

This is very cool news. 170mm is the crank length I use on my track bike, so I have already attained a range of motion sufficient for that, and my normal road cranks are 175mm. So I think in essence I have developed sufficient knee mobility for cycling. It still needs to improve but it's a lot better than it was.

From hereon it is about improving the functional performance of the leg, some weight loss through increased training and diet control and developing the aerobic engine required to drive me faster and put the hurt on a few guys.

Tomorrow is the State Time Trial Championships, so I'll be heading up to Calga to support a few of the lads who are riding.

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Race Report

Just a quick post today. No pictures.

I had a race today. One month after I gingerly first turned a crank on the trainer and nearly 16 months since my accident.

I drove on down to the local crit racing circuit at Heffron Park. No idea what grade to ride, I decided to start in E and if that was too easy then I'd pull out and wait for the D Grade to start. Well it turned out there was no E grade so I lined up for D grade. On the line I was seeing if I could do a track stand while we were waiting to start. I could. Geez - it's just like riding a bike.

Chatted with plenty of the guys beforehand and had to laugh at Jason Roberts who, when he saw me lining up and checking out the leg, called me "f***ing hard core man". I suppose that's one version of HTFU! Jason is one of those guys that could audition for the Hulk stand in job.

Before that I did some laps of the circuit to remind myself of those familiar bumps and turns. I also surprised myself by being able to do some pedal revs while out of the saddle. It's not pretty and I'll need a fair bit of work on the technique but it's a start.

As for the race, well not all that much to report really. I lasted 5km before being dropped, simply not enough horsepower to manage the (relatively light) surges of the D grade bunch but I'm not that far off D grade standard, so I have a reasonable benchmark to work from. After that I just circulated solo for a good 45-min training effort.

I had a little trouble as the new chain I have on is showing up the state of the chainring and under load it would skip most annoyingly and when I was attempting to pedal out of the saddle over the small rises, the chain would jump - it was hard enough controlling things as it was and it took a bit of care as I was putting my spokes into one guy's dereilleur at one stage. Will need to attend to that. To be fair, I think I'm due for a new race bike, there were that many creaks and groans coming out of this one...

Here are the stats for the day:

Crit Heffron D Grade:
Duration: 47:00 (1:06:06)
Work: 552 kJ
TSS: 96.5 (intensity factor 1.11)
Norm Power: 205
VI: 1.05
Distance: 24.462 km
Min Max Avg
Power: 0 748 196 watts
Speed: 3.7 44.9 31.2 kph


Entire workout (173 watts):
Duration: 1:15:55 (2:25:26)
Work: 786 kJ
TSS: 138 (intensity factor 1.047)
Norm Power: 194
VI: 1.12
Distance: 35.626 km
Min Max Avg
Power: 0 748 173 watts
Speed: 3.6 44.9 28.3 kph


We shall see what happens next week!

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Off the Air

OK - I've been off the airwaves for a little while. I was changing my internet service provider and that turned out to be a small pain in the butt but I'm back on line now - so time for an update on a few things.

Firstly, the above chart tells a pretty cool story so far. Each of those light blue columns is a day where I have ridden on the bike/trainer. The height of the column indicates how much stress I incurred on that ride (a combination of duration and intensity) and the dark blue line indicates my long term training load, curently at 23 TSS/day. Basically my objective for the coming weeks/months will be to keep training in a way that sees that blue line continue to rise at a sustainable rate.


In the one-month since first turning a crank over on a home trainer, I have:

- ridden on 23 of those days (mostly on the home trainer)
- progressed to using a 155mm crank on the left side (I started with a 100mm crank)
- had my special bike leg attachment fitted
- had two rides outdoors on my real bike
- been able to sustain 190 watts for an hour
- for the first time tonight I was able to do a couple of pedal strokes while standing up.

Here is the power file from my 1 hour ride in Centennial park on Sunday morning. I think an average power of 180+ watts for an hour with an average speed of nearly 30km/h ain't going too bad all things considered.



I was considering racing a crit this coming weekend but I just remembered I have some commitments (coaching at an intro to track session on Saturday). Might take the track bike out though and see how that goes....

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Inspector Gadget

OK - another pictorial adventure coming up for your viewing pleasure.

I recently reported on getting a dedicated bike leg attachment made up. Some aren't exactly sure what that means, so let me show you....

First we start with the leg I have today, set up as a normal walking leg.


If we zoom in to look at the special clamp at the bottom of the socket (the large black carbon fibre part that my legs fits inside of), you can see a number of allen key bolts secure the pipe section to the socket.


These can be loosened to remove the lower pipe section which has a foot attached at the other end.


Here you can see the two parts normally hidden from view, showing the unique block style clamping system. There are four of those allen bolts, one on each side and they enable you to adjust the angles at which the pipe section fits onto the socket.


As long as I only ever undo two of these bolts (must be next to each other and not opposite) then the attachments will always clamp back on in exactly the same place each time. If I loosen three bolts, the the positioning changes. Hence I have put some loctite on the two bolts I don't intend to undo.

Here is a picture of the walking foot attachment and my cycling "foot" attachment. As you can see, there is no foot for the cycling leg. It is simply a pedal cleat attached to an adapter plate right under the end of the pipe. This enables direct force transfer down through the leg, the socket, the pipe section and onto the pedal.


Here is a picture of the cycling leg attachment connected to the socket.


On Monday I visited my good buddy, Steve Hogg at cyclefitcentre.com. Steve specialises in fitting bikes to people. So away I went and we worked on getting the bike leg attachment adjusted for length and all the multitude of angles you can adjust. Indeed it's almost as if there is too much adjustment available!

The best part was that we discovered that my knee was able to cope with using a 155mm long crank arm. At the moment I have a short 100mm crank on the bike, as I hadn't been able to bend the knee enough to use a longer crank. On my road bikes I normally use 175mm cranks and on the track I use 170mm. So my leg has improved enough so that I am not far away from using a full length crank.

That is really important as it means I will have a much greater ability to get power through to the pedals.

All I need now is a 155mm crank arm. I have a buddy looking into that for me (he made the short crank up for me), although I know there are manufacturers of cranks that small, normally designed for BMX riders, so I'm pretty sure finding one won't take long.

Then I expect to graduate to 160mm, 165mm and hopefully at least 170mm cranks.

Ultimately I would really like to have a dedicated cycling socket, so I can simply transfer from a walking leg to a cycling leg without having to bolt things on and off. Also, the design of the walking leg socket is not quite ideal for the way I pedal the bike - there are a large number of dynamic factors at play but basically the lower socket shape angles outwards when it would be better if the line between the knee, lower socket and pedal was aligned. It will certainly do for now though.

The best way to make sure that happens is to keep riding!

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