Friday, July 09, 2010

Ascension Rates and Power to Body Mass Ratios

As many of you know, the cycling speed attained when ascending steep climbs is primarily a function of a rider's sustainable power to weight ratio. More power and/or less weight means a rider can climb faster. Pretty simple really.

But it's not the only factor to consider. For instance, wind can still play a sizable role in speed attained. And of course when climbing in a race, race tactics will play a role, with attacks, surges and pacing by team mates (or motorbikes!) all serving to alter ascension rates for a given power output.

Recently there has been some (typically annual) discussion on a few cycling forums about ascension rates of pro riders, estimated power to weight ratios and whether or not such performances are plausible sans-doping, even suggesting that some ascension rates cross over some level of "sans-doping plausibility" and should be a red flag to anti-doping authorities.

Well I'm not going to delve into all aspects of this issue other than to say that, in essence, there are so many variables that such an approach is really a pretty futile exercise.

In the end, all the pro riders that demonstrate such tremendous physical acts will already be under the eyes of anti-doping authorities, so I really don't see how such an idea really adds any value to the issue of doping in cycling.

Many issues of a physiological nature have been batted about, and there are a couple of excellent summaries of some of the science demonstrating the massive variations in such estimations in these two items by Dr Andy Coggan:
Superhuman Performance? Part I
Superhuman Performance? Part II

Nevertheless, I thought I would look at the challenge of estimating power to body mass ratios from ascent times up one of the most famous climbs in Tour de France history - Alpe d'Huez. Below is a chart summarising (click on the picture to see a larger version):

In modelling of cycling power and speed, I used the mathematical model as per the 1998 Martin et al paper:
Validation of a Mathematical Model for Road Cycling Power.

The equation in question is shown below:

For the purposes of this exercise, I have simplified the equation a little. The main assumption being that of reasonably steady state cycling and no change in kinetic energy from start to finish (which is reasonable assumption given that the difference in speed from start to finish would be negligible and over ~40-minutes is a tiny proportion of overall energy demand). If there are a lot of surges or changes of pace along the way then a little more of the overall energy demand may go into changes in kinetic energy.

Then there is the climb itself. I have used a course elevation profile which, as far as I can tell, corresponds to the timing points which have been used to time the ascension up Alpe d'Huez since 1999. Before then different measuring points were used. My data indicates a climb of 13.93km with 1085m of vertical ascent (there are a few metres of marginally negative gradient right at the top).

I divided the climb into 56 segments of 250 metres (final segment a balance), with each segment having a gradient and wind vector assigned. The modeling then applied the maths to the segmented climb.

The following additional assumptions were used for the modeling:
- Rider mass: 70kg
- Bike + gear mass: 8kg
- A coefficient of rolling resistance (Crr): 0.0045
- A coefficient of drag x effective frontal area (CdA): 0.300m^2
- Air density: 1.046kg/m^2

Importantly, I have also assumed an even application of power for the duration of the climb. Of course no rider applies power perfectly evenly up a climb, although climbs with relatively consistent gradients generally produce consistent power outputs (if you inspect power meter files, you can usually pick the climbs as the power line is smoother and speed is low).

Then what I did was to calculate the ascension times up the Alpe d'Huez course profile for various power to body mass ratios, with a 2.5 m/s tailwind (9km/h), with no wind and with a 2.5 m/s headwind.

One can then see the quite sizable role that wind can play in estimating W/kg from ascent times.

To read the chart, for instance, take a time of 40-minutes flat (40:00) on the vertical axis and see where that time intersects the diagonal lines marking the tail-, no- and head-winds. The horizontal axis then marks the corresponding W/kg required for that time.

So, for 40:00, depending on wind conditions and assuming even pacing (and other assumptions as listed in the chart), then the power to body mass ratio required would range from 5.6W/kg for a tailwind to 6.35W/kg for a headwind.

Alternatively, if you are a 5.9W/kg rider then you could attain a time anywhere from 38:10 with a 2.5 m/s tailwind through to 40:00 with no wind and 43:00 with 2.5m/s headwind (off the chart).

I then added lines to mark the ascent times for various riders I selected from this Alpe d'Huez Wikipedia reference. Note that the times from 2004 were an individual time trial, the rest are final ascents during a TdF stage race. As we can see, the estimated power to body mass ratio for Armstrong’s super quick ascent time in the 2004 Individual Time Trial falls in the 6.00-6.85W/kg range, depending on overall wind direction.

Times for other riders in earlier tours such as Pantani were not taken using the same timing points, hence I have excluded them.

Of course the course winds its way up the ascent in various directions due to the famous switchbacks, and any wind vector would naturally vary accordingly, so by putting an indicator of reasonably modest but noticeable winds, at least one can see that any given ascent time will still end up with quite a wide range of possible power to body mass ratios.

All I can say is, given that some believe there is a performance level that is beyond plausibility sans-doping (some have suggested 6.2W/kg, some less, some more) then all the climb times listed in the chart straddle such "plausibility levels" with such a large range of uncertainty that it is simply not possible to draw any firm conclusions on power to mass ratios from ascent times alone.

Keep in mind that the highest ever 1-hour power to body mass ratio known and recorded is 6.4W/kg by, as far as is understood, a non-doped rider.

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Sunday, April 11, 2010

Bon Anniversaire III

Three years today since my accident.

I’m not sure sometimes if it seems like yesterday, or a lifetime ago, as the temporal distance sensation oscillates from day to day.

One thing is for sure, I am mostly looking ahead and not back. But anniversaries (good or bad) tend to be times for reflection. So it is once again with today’s post.

I did previous post-accident annual reviews in these two posts in 2008 and 2009:
Bon Anniversaire
Bon Anniversaire II

It’s been, all up, a pretty darn good year with more change and plenty of challenges. In keeping with the theme of this blog, I’ll go over my rehab and cycling related topics for the past year and leave out other personal stuff.

My physical rehabilitation has progressed very well. I upgraded my general prosthetic in June 2009 as I had “under grown” the other one. I say “under grown” as my fellow acquired amputees would know that the residual leg (or “stump” as we call it) gradually shrinks over time, until it settles after 2-3 years. It does continue to change over the years.

Prosthetic sockets, being hard inflexible containers for your stump, eventually have to be re-made to suit your new size and shape. In between times, you adjust to it each day, and through the day, by using different size, thickness and number of socks to provide for more or less compression as comfort dictates.

One frustrating aspect was my early use of the new prosthetic didn’t go so well. My knee reacted badly and it broke open the skin on the inward side of my knee and the rubbing against tendon created significant discomfort. My knee swelled and I couldn’t get my stump into the socket. Which sucked. A lot.

Eventually it settled down and I could get back to “normality”.

The open sore / hole in the side of my knee created in June 2009 is still there today. It simply won’t heal up. I’ve tried all sorts of tricks and tips to fix it but with no real success. The only option I think is to not wear a prosthetic for as long as it takes to properly heal over – which I would estimate to be maybe three or more weeks. That’s just not really much of an option when you’re a cycling coach. But it may come to that one day.

Most of the time it’s not so bad, but occasionally it flares up and the knee swells and it hurts when I put the leg on, sometimes standing/walking can be very painful. Sometimes I can’t get into my prosthetic at all. It happened again in December 2009, and the same thing has happened this week. So far I haven’t been able to nail down a consistent trigger for it – which is something I really want to do, as if I know how to avoid it in future, then that’s what I’ll do!

Cycling Performance
Those leg troubles aside, my cycling performance improvement has been excellent. So much so that in the past six months I have actually exceeded pre-amputation power output levels over significant durations, both in terms of absolute wattages, and expressed as power to body mass ratio terms.

I did this post on Power Profiling in January, which compared my then post-amputation power profile to my pre-amputation power profile.

Here’s another chart to show my progress since I got back on the bike in June 2008. It shows the maximal 1-hour (normalised) power I attained in each 90-day period since starting riding again, right through to today. I chose normalised power as it provides a sensible comparison of my performance capacity across all types of racing and training, and represents a very good estimate of the progression in my Functional Threshold Power.

As you can see, my progression has been consistent and steady, culminating in a 1-hour race power last weekend exceeding my all time best except for just one occasion from my pre-amputation racing days (that was during the State Criterium championships in 2006 at 337W).

In fact, in that race last weekend I set my all time highest 2-hour normalised power of 315W.

I must admit, I do surprise even myself at times.

Of course, all the way through this I have had fantastic support from many people, especially from my coach Ric Stern. We are setting no limits on what's possible. Heck, when I can outperform what I did on a bike before an amputation, then what else can I do?

Nevertheless, I still have lost significant elements of my cycling capacities, most notably my sprinting and standing start abilities have been curtailed somewhat. Which just means they may require more work in order to close that gap as well.

Cycling Leg
After getting my new general purpose leg, I also worked on adding a dedicated cycling leg to my “stable”. Previously, in order to cycle, I used to screw off my walking “foot” and screw on a cycling “leg” attachment. It enabled me to ride but it was a PITA having to keep screwing them on/off, and the constant changing would not have been doing the components much good (one day I found one clamp had completely cracked through). And being very sensitive to the set up of the bike leg (lengths/angles etc), this process did have a habit of unintentionally changing the set up at times, enough to cause discomfort or pain when riding.

Getting a dedicated leg would make sure the set up was better suited for the bike, and have the ability to quickly remove one leg and put on the other, if for instance I wanted to hop off at the track and walk somewhere.

So it was back to George at the Appliance and Limb Centre for the bike leg socket design. That bit wasn't so hard as it was really a replica of my existing general purpose socket (all carbon fibre custom moulding) although that might be understating it a little. The funky bits were what we attached to it and the design of an aerodynamic outer shell.

It was all made possible with the funding raised by the local track cycling community organised by Paul Craft of RAW Track fame (and donations and help from wonderful people all over the world), who generously raised about $8000 to cover the costs. The leg was built and we designed a funky aerodynamic carbon fibre cover for it. The leg cost $7600. Add to that a new stump liner at $1000 a pop (and which wear out pretty quickly I’ve since discovered, needing several per year), and well, there goes the $8k!

Also a big thank you to John Bosevski of Cycle Underground who engineered a special adapter plate for connecting the standard prosthetic block to a standard 3-hole cycling cleat. That was based on an original version Peter Barnard made for me in his home workshop.

Steve Nemeth, CEO of Bont Shoes, supplied me with custom mouldable Bont road and track shoes, which have been great (thanks Steve). If anyone needs a size 44 left Bont cycling shoe - let me know - I have two of them spare!

That lace up track shoe is the best I've ever used. Steve has also helped with a few other bits for me. In a semi-related note, just last week I was contacted by a fellow from Canberra, who was in touch with a guy I know in Perth, who for some reason ended up with a spare right Bont shoe in my size. I don't know what happened to the left one and so he generously mailed the spare shoe to me!

Of course getting the leg sized up and fitted properly for the bike - well I was helped by none other than my good buddy and bike fit guru Steve Hogg of Sydney Cyclefit Centre. It was amazing how just the smallest tweak in the grub screws at the bottom of the leg make a large difference in my ability to pedal effectively and in (relative) comfort.

The leg has been great and has been very well used so far and the support I received was, and continues to be, amazing and I am very grateful to everyone for helping.

In April and May 2009 I competed at both the Para-cycling National and Oceania Paralympic championships, my first attempt at Para-cycling events. I picked up a silver medal in both the road race & time trial at the Nationals and two Gold medals in the same events at the Oceania Paralympic event held in Darwin.

In August I started racing back at the track during the Friday Night Winter race series, and even won my first track race since returning. It was good to be back on the boards. The previous year when I couldn’t race, I was the Chief Commissaire for the series. This time I did half the series as commissaire / half racing.

In October 2009 I raced the UCI World Masters Track Championships. I surprised myself with my 3rd fastest ever 3km individual pursuit and made the finals of both the scratch and points races. I was very happy with that, partly because in 2005 I set out with the goal of making those finals in 2007, but my accident happened in the lead up to the 2007 event and destroyed those hopes. I was also surprised because they were very hard races and there were some pretty fancied names that missed out on finals. It just showed me once again what was possible provided you keep at it, remain positive and do the work necessary.

In November I ventured back to doing an open track race carnival up at the Central Coast (always good carnival that one). It was a successful night and I won one race, took three second places and a 5th in the open miss ‘n’ out race.

My form kept building and I started to approach pre-amputation power output levels. Maybe, I thought, I could get there....

Then, bang – I go and do some time trial training efforts at a power higher than pre-amputation levels. Holy smokes!! OK, don’t stop now :D

All this was of course part of my plan to race the National Para-cycling track championships earlier this year and come home a National Champ. I ended up not even going. I’m not going to bore you with the details, just to say that bureaucratic stuffing about regarding State selection policy left me in no-man’s land for the second year running, unable to plan for the expense and time needed to participate and I had to commit to other things. My form was excellent. Shit happens they say.

The experience left a bad taste though and I struggled for motivation for a little while after that episode. But we move on. I am now somewhat ambivalent about para-cycling competition. Apart from the good encouragement I receive from other para-cyclists, I experienced a less than enthusiastic level of interest from officials in seeing more riders compete at championships; indeed it seemed as if there was active dissuasion going on. Turns out I wasn’t the only one to experience that, which was kind of good (in a bad way) as it meant I wasn’t just being paranoid.

Eventually I got myself going again, and as always the best thing for me is to pin a number on my back and go race! I just love racing so I raced some local criteriums. What grade? Well I started with the local open C-grade.

Oops, won that comfortably.

Next time out I went to B-grade....

Oops, I bridged across to a break and the three of us circulated at same pace as A-grade and left the rest of them to fight it out for nothing. OK, so I’ve been re-graded back into A-grade. LOL.

Last weekend I raced a local Masters Enduro – a 2 hour + 1 lap affair. What a corker of a race! Apart from helping a mate (& client) get into a successful 3-man break, along the way I generated my highest ever 2-hour race power and 2nd highest ever 1-hour race power. Here I am poking my tongue out for a bit of fun when I spotted photographer Ernie Smith.

OK - I nicked that pic off Ernie's website - I'll sort that later with him :-)

In September & October 2009, I had a wonderful experience all down to the generosity of Steve Palladino and family, who invited me to stay with them in Santa Rosa.

While there I delivered a seminar on Training and Racing with a Power Meter (talking about a case study in application of a power meter to help Jayson Austin achieve his world masters hour record), did some great training rides with Steve, culminating in Levi Leipheimer’s 170km GranFondo along with the Fightin’ Boba crew. It was fantastic.

My coaching activity took another step up through the past year, it’s now the sole source of my income and I love it. I have a great group of clients, spread all across the globe ( I currently have coaching clients located in seven countries) and I really enjoy helping them to perform even better than ever.

Some great results from riders & teams I coach, including multiple State & National championship wins and one world record. Here's a pic of Jayson on his way to a UCI world record.

I started up a new product, customised 3-month training plans, which have been very successful with sales going worldwide including the UK, Europe, Africa, Middle East, USA, Canada, New Zealand and of course all States of Australia. Lots of great feedback with people reporting excellent results and coming back for their second and third plans.

Along with Joanne Palazzetti, I have been very busy with the establishment of a new indoor training centre for cyclists and triathletes – the Turbo Studio. We commenced operation in February 2010 and so far the response has been excellent, with really good growth in client numbers - already some of our sessions are full.

People are really responding to the professionalism of the set up and having a dedicated cycle coaching resource available to guide them in the right direction and answer their various enquiries about training. Half the time is spent dispelling training myths and educating about the use of power measurement in training. It’s all evidence-based training principles and the results are speaking for themselves.

I want to thank Jo for her totally professional approach, creativeness, passion and friendship in getting this project up and running, and for asking me to come on board and just do what I do – i.e. help people get the most from training with power!!

Added to that, I began a power meter hire business. That’s also going well!

Ric Stern & I have been working on other things at RST, with Ric getting the website updated with many new features including the establishment of a new forum for all things bike related – especially about training and racing and to support all our coaching clients around the world, including those who are using our Training Plans. The members' forum is available for anyone to join.

Not stopping there – we have other projects in the pipe and expect to announce shortly the addition of new coaches to the RST crew. We have a pretty thorough selection process as we seek to maintain the highest standards in professional and scientific coaching services.

I also embarked upon something I expected to do years ago, and upgrade to the Cycling Australia Level 2 coaching accreditation (I was scheduled to do it in 2007 but my accident got in the way of that). Level 2 is the highest level of accreditation available in Australia bar those on CA staff who are required to do a Level 3.

So far I’ve done part I of the process, which was to attend the week-long CA coaching course in November & December but I still need to complete the balance of activities. It’s just been overly busy since then, especially with the setting up of a new business but I’ll get back to that as a priority over the next few months.

It’s not like I’m not doing practical coaching – it’s what I do for a living and I supervise training groups every working day, write about it constantly and so on.... :-)

So what lies ahead?
Well I expect to keep plugging away with my training and racing ambitions. My racing goals however are a little fluid at this stage and so I’ll likely do some Masters championships along with local racing for the next block. I will continue to pursue improvement in my form and power and to race regularly. Let’s see how much further I can drive my development as a rider.

Business wise there is much to look forward to this year – the Turbo Studio will keep forging ahead, I expect squad training to become part of life, power training seminars to be delivered and of course we are introducing the Winter Indoor Race Series on the Turbo Studio’s Computrainers, which should be a lot of fun. Given there’s about $5000 in prizes (mostly cash) up for grabs, I’m sure it’ll be popular.

My clients have tremendous goals to achieve and I’ll be working hard to help nail them and take them all to a new level of performance. Championships, sportives, category upgrades, commencing racing, all sorts of new goals and challenges.

RST goes from strength to strength and is growing as well, so more to come on that front, including some more new training products on the (hopefully near) horizon.

I expect to complete my Level 2 coaching accreditation as well.

At the moment I am also slated for a return to California in October for the Granfondo, so that should be another epic adventure.

OK, that was a long post, but hopefully not too dull a read. Perhaps you can see why my blogging frequency has dropped a little lately. Of course there's lots of more personal stuff that I don’t write about on this blog (that’s my business!) and there has been plenty to work with on those fronts as well. All up, it’s been another cracker of a year and I hope to make this next one even better!

Safe riding out there.

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Monday, February 22, 2010

Where the blogging heck have I been?

Collecting race winnings at Heffron Park, that's where!

In reality I've just been really busy with lots of stuff and blogging has taken a bit of a back seat for a little while. There is much to write about, just not so much time to do it lately.

So what's new in the Zoo? Plenty!!

Business wise I've been busy with the opening of a new indoor/outdoor cycling training centre here in Sydney - Turbo Studio. Click the link for a peek.

We opened this month and all is going really well. Some are now finding out just how effective a focused power-based indoor training session can be. It suits riders of all abilities as all sessions are set relative to each rider's individual fitness level. That's the great thing with the Computrainer's Multirider set up. And I've been designing the sessions with Erg+ software and next week we are looking to add the real erg videos to the sessions for some extra fun.

Training and race wise, I've been going nicely since the new year ticked over and I cleared a knee injury in December. Threshold power is back to around 300W and I've done three races so far this year, two others were washed out/canceled due to the pile driving rain we've had in Sydney during February.

So it's been three crits so far, all at a local crit circuit, Heffron Park.

I won my first race on 16 January by a country mile and the next week I raced the Australia Day crit (26 Jan), where race promoter and handicapper thought I should be bumped up a couple of levels and race with the likes of Stuart "Computer" Campbell.

Not quite sure how the A grade riders get to race B grade (this is an open race) but nonetheless I hung in there. I suspect I was lucky to be allowed to start at all but that's another story ;-)

That race was ~ 45-min with NP of 319W, Average Power 294W. I was digging hard at times but it was good fun.

Winning the sprint at Heffron

On Saturday just gone, I raced up a grade at Heffron and after the usual opening flurry of attacks (one of which I calmly closed down), I saw two guys attack into the wicked northerly wind and thought to myself "they look the goods", so I took off after them. Nobody followed me.

I then spent the next half lap bridging across and then the three of us decided to work together with the bunch following at about 30 metres. We all committed and the gap began to grow, until after a hard five laps or so I think we cracked their spirit and so we settled into a grind to the finish, never really letting up the pace until the final lap or so. I initiated the sprint, kept it clean (line wise) but was overhauled about 20-metres out and settled for second place. Still getting used to my new level of sprinting. As they say, when in doubt - lead it out.

Longer race this time, ~ 52 min with NP of 319W and Average Power 302W. So fitness is coming along nicely and I look forward to the State Points race championships this weekend coming.

Also keeping me busy is preparations for the Team Pursuit championships. I've been my Club TP coach for a few years now. This year is a little different. I am actually going to race it this year. I'm really happy about that as the TP is my favourite bike race. And it would seem I definitely have the legs for it this time.

As for other training related items, I have a few things banking up to write about - one an item on Quadrant Analysis and maximal force velocity data and another on the relationship between performance in individual pursuit and power/CdA ratios. And another is to finally do the write up and pictures about my completed prosthetic racing leg.

And I hear a whisper about a wind tunnel in Sydney.....

All good stuff. 'til next time folks, safe riding!

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Saturday, January 02, 2010

Power Profiling - Now and Then

Often I am asked how my cycling power ouput compares now, to before my accident and amputation.

As I progressed with my training during 2009, and as my fitness continued to improve under Ric Stern's guidance, the answer to that question kept changing, mainly as I started to close in on pre-amputation power levels.

Now that I have a full year's worth of data from 2009, I decided to take a look at my annual power profile and see how it compares to pre-amp levels.

Below is aggregate power profile data covering the past 5 years. It shows my best power to mass ratio (W/kg) for each of 4 separate durations for the years 2005 through to 2009:

The power durations shown are:
5 seconds
1 minute
5 minutes, and
95% of my 20-minute power.

Each of these power-durations represents key elements of cycling fitness, with different energy systems being the primary contributor to performance at each duration. That's why it's such a telling indicator of your overall cycling makeup, and an excellent indicator of your relative strengths and weaknesses.

This is provided of course the profile does in fact contain data from best efforts for the duration. Given it's aggregate data for whole years, then I think it's a reasonable assumption. Nevertheless, sometimes the 1-minute column can still be under stated as that usually requires dedicated efforts not often performed in training or racing.

You can read more about power profiling in this original item by Dr Andrew Coggan here:
Power Profiling

So the group of columns on the left shows my best 5-second power to mass ratio for each year from 2005 to 2009. Each group of columns moving to the right covers the other durations, with 95% of 20-minute power shown by the columns on the far right.

What matters with power profiling is the overall shape of the profile, rather than the absolute numbers. The shape in this case indicated by the lines joining the columns, which I have shown for 2006 (orange line) and for 2009 (blue line). I chose those two years as they are the two complete years representing pre-amputation and post-amputation training/racing data.

I notice a few things:
- the overall shape of each line is similar
- my short duration power has taken a large nosedive
- my longer duration power to mass ratio is actually higher than previously attained

This clearly demonstrates that it's my sprint power that has suffered the most from my lower leg amputation, yet the predominantly aerobic power durations (5-min and 20+ min) have not.

This suggests a few things to me.

One is it's an example of how we are not force (strength) limited when cycling at aerobic power levels, since even though I have lost significant leg musculature and with it strength, I have still been able to generate the longer duration power.

Another is that the lack of a lower leg muscular-skeletal system has a significant impact on sprint ability. The lower leg matters a lot more in the generation of short duration sprint power, than for longer duration aerobic power.

What can I make of this information? Well for one I no longer have the sprint I used to, yet I am as likely to be as well set up for the end of a race as I was before, since I have the engine to deliver me there. But now I lack the finishing ability. My strategy and tactics in racing may need to be modified a little as a result.

I can still work on improving my sprint of course (all track/roadie riders should) but I would say that reclaiming pre-amp sprint power levels is not going to be anywhere near as "easy" as it was for aerobic power durations, if in fact it is actually possible.

It also points to me reconsidering what events I may in fact focus on. They may change as well.

Plenty to ponder with a power profile.

What's yours look like?

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