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Monday, 11 August 2014 00:00

Aero shrug

There are a number of adjustments that can be made to your bike that have an effect on power production, comfort and aerodynamics. A successful bike fit will gather information on the relative importance of each of these three aspects and then adjust accordingly. For example a track pursuit rider will be interested in optimal aerodynamics and power production at the expense of comfort (pursuiting is very uncomfortable regardless!) whereas for a long distance cyclist comfort takes on a much more important role. For every athlete and every event there will be a slightly different balance that must be achieved. What is often not addressed in bike fit sessions is the different ways a cyclist can sit on the same bike to get a very different position to the one intended. Tony Martin offers an extreme example of this in the picture below but there are more subtle tactics that can be employed to safely increase your performance.

Tony_Martin_aero_descent

An example of this that many of the PBscience athletes have been using over the past seasons is the 'aero shrug'. It's another item that I was reminded of at the recent WCCS in a presentation by Andy Froncioni (twitter: @AndyFroncioni) of Alphamantis technologies. Oli is much more of an expert on aerodynamics than me and describes the shrug as follows:

"Press your chin forwards and down towards the top of your stem, then 'shrug' your shoulders towards your ears (it should feel like they roll up and in over the back of your neck). Keep your head still and relaxed and maintain the natural curve of your spine."

They say a picture saves a thousand words so the following two shots in a layby on the Farnham 10 course are the perfect example of the aero shrug from Jill. Using the shadow behind as a frame of reference you can see how much the head position is dropped and the light patch on the grass shows how much narrower her shoulders become.

Jill_non-shrugJill_shrug

Onto Andy's presentation at the WCCS... if you're not convinced by measurements using shadows and light patches of grass (!), then the following slide shows calculations of CdA for mulitple laps on a velodrome. Alphamantis technologies have developed a robust means of evaluating aerodynamics with field testing. If any of you have used Golden Cheetah's aerolab feature you'll understand the gist of this. The following slide gives the results of this technology applied to our aero shrug. The first five laps establish a baseline, before we see the effects of a shrug on 6 laps and then a final four laps back at baseline. Now we have data showing that a shrug can have a real and measurable difference on a rider's aerodynamics.

Aero_shrug_data

A few caveats:

  • the effect of a shrug will vary for different riders, some will benefit greatly and others not at all
  • sustainability is a problem - you can overcome this a little with practise but it can be quite uncomfortable. In Andy's slide you can see the effect wearing off in the last two laps, presumably as the athlete struggles to hold the position. So a pursuit rider might be able to hold said position for the whole of their race with practise but in a road TT may need to pick certain sections, for example headwind sections.
  • because of problems with sustainability, it might also be possible to make changes to your position that have a similar effect to the shrug (head drop, narrow shoulders). This would be preferable to having to force yourself into position!
  • Similarly, improved flexibility/mobility through the arms, shoulders and upper back are of importance when adpoting an optimal head/shoulder position.

Give it a try in front of the camera and see if you can spot a difference. It might be worth a few seconds in your next race against the clock! 

Friday, 25 July 2014 00:00

Stage race nutrition

Oli and I recently visited the World Congress on Cycling Science in Leeds in the run up to the Tour. The list of speakers read like a who's who from the world of cycling science but the aspect that struck me most was the clarity with which the top experts present their knowledge of their subject area. I heard a few complaints from other delegates that nothing in the presentations was particularly groundbreaking but for me the opportunity to hear it 'from the horses mouth' is invaluable. There are always nuances and subtleties that don't often come across in research papers or books so I found it a very worthwhile trip. In the spirit of clarity of message, I've took photos of a number of key slides that I thought were particualrly clear with the aim of writing blogpost summaries on those topics. The factsheets on the website have a lot of info but I admit it's often not in the most practical of forms. This is my attempt to mitigate that.

First up is a slide from Dr Peter Hespel who works as head of nutrition for Omega Pharma Quickstep. The subject of his slide was on stage race nutrition. The aim with your on-bike nutrition during a stage race is to maintain energy for the duration of the stage and minimise the recovery needs post-stage so you're ready to go again the following day. What follows is a template representing best practise that can be adapted based on individual and event specific demands. I've been helping Christoph and Mark with their preparations for the Haute Route this year so this is with you guys in mind!

Stage_race_nutrition

  • The number one principle for your on bike nutrition is 60g of carbohydrate (CHO) per hour. This represents the maximum rate at which carbohydrate can be digested and absorbed from a single source of sugar (for example maltodextrin)
  • an additional 10-30g of CHO can be used with the addition of fructose which uses a different transport mechanism within the body. Commercial energy drinks make use of this by using a 2:1 mixture of maltodextrin and fructose. You must practise with this in training - close to the upper limit of 90g of CHO per hour you may find you suffer from GI distress. Fructose is also very sweet.
  • For stage racing, 10-20g of protein and 5-10g of fat can offset some of the catabolic processes that are a problem with long stage races and training camps.
  • Solid food should be consumed earlier in the ride (it takes time to digest) and as time goes on liquids and gels allow for faster digestion and a more immediate release of energy.
  • Volume of fluid should be matched to temperature and individual sweat rates. (My advice is if you never need to stop for a pee on longer rides then you're probably not drinking enough).

Those guidelines are explained in the above slide and should form a basic template for every stage. It's worth remembering that you are also fuelling for the following days as well as the current ride. Make sure to follow the plan right until the end of the ride - it's easy to think that you'll get home regardless when there are only 45 minutes left but if you stop fuelling at that point you're increasing the recovery demands post stage. The above template is also perfect for long single day rides, but you can remove the protein and fats to lighten the load on the stomach.

Post stage you're looking at a recovery shake with ~1g of CHO and 10-20g of protein immediatley post stage and then drip feeding CHO and PRO throughout the rest of the day and evening. Rehydration should also be a priority with 1.5L of fluid for every kilogram of weight loss during the stage a good rule of thumb. The addition of 1g of sodium per litre of fluid will aid absorption (plain water tends to go straight through) and will trigger a thirst response to help get the fluid down. Sleeping when dehydrated will massively hinder the recovery process so another simple tip worth it's weight in gold is to check the colour of your urine before bed - if it's the colour of a 'Heineken light' then head off to bed, more like a 'Belgian Tripel' and you need to drink some more before lights out!

Along similar lines, I also came across this video of Helen presenting some of the research and practicialities of carbohydrate loading at one of our workshops a few years back. Worth a look for those big one day events or for the lead in to a stage race.

 

Tuesday, 01 April 2014 00:00

Endurance

Any sport with events lasting more than a minute or two can be defined as an endurance sport but today I'm going to write about those sports at the more extreme end of the spectrum. Milan Sanremo has been and gone for another year and once again we were treated to that wonderful spectacle of the top pros trying to sprint at the end of 300km in the saddle. MSR is the longest one day race that the professional peloton now races but it hints at a theme that is pervasive throughout both the professional and amateur cycling world - the subtle difference between fitness and endurance. Alexander Kristoff summed it up nicely with his post-race press conference when he said (and I paraphrase), "I would not normally expect to beat Cavendish and Greipel in a sprint but it's different after 300km and I tend not to lose too much power".

So if we think if fitness as the ability to produce a certain amount of power, ie your power at lactate threshold or your power at VO2max for example, then endurance is the ability to maintain that power over a long period of time, or to produce that power at the end of a long ride. It's one of the key factors in deciding professional road races where the result is often decided by a short maximal effort late in a race, but it's also important in amateur races, in sportives (for example the Etape this year finishes with the climb of Hautacam after 150km in the saddle) and also in multistage events where fatigue accumulates through the week. The concept of endurance has been vital in the last few years for some of the PBscience athletes: it's been a key area of focus for Nic who races professionally for Team Vorarlberg, also for the guys and gals we've worked with in preparation for the Haute Route sportive and it goes without saying that endurance played a key role in Pete winning the National vets 24 hour title. Here are some of the strategies that we've used to enable our athletes to produce their best efforts when they count, be that at the end of a tough road race, or several days into a mountainous endurance event.

Consistent mileage - it's hard to look past an accumulation of time in the saddle when it comes to building endurance. An increase in muscle glycogen stores is one of the first adaptations that takes place when you begin a program of endurance training but that tends to max out after 10 weeks or so (Griewe, 1999). We're also looking for a homogeneity of muscle fibres - as you fatigue a set of motor units, you're forced to recruit new fibres that initially may not be as well conditioned as the slow twitch fibres that are the first port of call. It takes a little while to develop the condition in the whole muscle bed so that you don't get wild ups and downs during a long ride. And having spoken about maximising carbohydrate stores, another fuelling issue is the need to become fat adapted, that is to develop the ability to efficiently use fat as a fuel in order to preserve your precious carbohydrate stores until later in the race.

Nutrition - beyond simply riding your bike, a little care can be taken with fuelling to improve or speed the adaptations we're looking for. For example fasted riding or train low race high is a strategy that can be used to aid process of fat adaptation. Of course beyond that, 60-80g of CHO per hour during the race itself is vital to keep stores topped up.

Specific training - I guess the most specific ride you can do in this situation is the long base ride. By long I mean efforts in excess of 3 hours as going beyond this duration places a demand on fuelling beyond the stored glycogen in your muscles/liver/etc. There's something about a 5 or 6 hour training ride that seems to cause an adaptation that is hard to replicate! In terms of a progression, or if you're short on time, you could try a 'tempo finale' or a 'tempo sandwich' (makes me hungry just thinking about it), or a very specific workout for road racers is to complete high intensity intervals at the end of a long ride. Alternatively, if you're fitting training around work, a steady endurance ride in the morning followed by intervals in the evening is a popular way of learning to make a hard effort when fatigued (or atleast not fully recovered).

Weight training - the jury remains out on whether strength training improves cycling performance and the sports science research isn't too enlightening in that respect in my opinion. There are an abundance of studies that are open to criticism; for example studies involving:

  • strength programs involving nothing but leg extensions (who would do that in reality?!)
  • untrained participants
  • unmatched total workloads between strength and non strength training groups
  • etc

That said, there have been a few good studies such as those by Bent Ronnestad that I think do carry weight in this area. One such study for example tested the effect of adding strength training to endurance training on a five minute all out effort. Interestingly for the purpose of this blog, the five minute effort was completed after 185 minutes of endurance riding to simulate the latter stages of a road race. Sure enough strength training improved average power in the strength plus endurance training group by almost 30W. Performance improvements aside, anecdotedly I've found that some element of strength training does allow for improved comfort on the bike on very long rides, whether that's improved core strength, addressing muscle balances or just an increased level of general conditioning I'm not sure but it's a mental boost to know you've ticked another box. Wishing you'd devoted some time to a core program is quite distracting in the 9th hour of a 12 hour ride for example!

Pacing - the above strategies are all ways to improve your endurance, but there is also much you can do in practise to make best use of that endurance. Avoiding hard efforts early in a ride will protect muscle glycogen stores that can be called on later in the ride. The perfect example for this is in road racing where top riders will give themselves sliding room on climbs. If you start the climb at the front of the bunch, you may be able to ride a hill 30s slower than the rest of the riders and still retain contact with the back of the bunch as you summit. It's risky if you think the race might split but otherwise you can move back up when the race eases off having saved yourself a few watts on the climb. Alternatively if you can't climb for toffee then this might help you stay in contact on a hilly course but that's a topic for another day.

Tracking improvements - the scientific method requires that we quantify endurance in some way to ensure that we're actually making improvements. Aerobic decoupling or cardiac drift is one way to assess your endurance (see Helen's presentation below or our factsheet on decoupling). Alternatively, something I've used a little more is a specific performance test where the athlete is required to produce a max effort over a set duration at the end of a long ride. For example, try completing your 20 minute FTP test after a three hour zone 2 ride, or ride a 5 minute VO2max type effort at the end of your long ride. You can come up with something that matches the demands of your event, but make it repeatable.

 

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