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Exercise Physiology/Testing


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Swim Technique/ Biomechanics

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Run Biomechanics/ Technique

Environmental Considerations (Heat/Altitude)

Strength and Flexibility/ Injury Prevention

Race Strategy/Selection

Performance Modelling

Genetics/Talent Identification/'Trainability'

Health, Overtraining & Recovery

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Tweets by @Alan_Couzens

How often should I breathe when swimming?…

Alan Couzens, MS (Sports Science)

Sept 12th, 2014

As often as you need to!
... end of blog :-)

Well, that short, simple answer is 100% spot on but I know you want more info that that. So here goes….

I saw this great article on on the subject of breath frequency while swimming & figured I would add some quick observations on the topic.

If you ask around the elite triathlete ranks, you might be surprised by the intensity of views on this subject. Some will swear by the stroke balance that breathing every 3rd stroke provides while others (typically ex pool swimmers) will sing the praises of the extra O2 that breathing every stroke offers. So who is right?

There is good reason for the intensity of positions on the subject – this O2 thing is pretty important! In short, it’s so important that other stroke considerations will be built around ensuring its adequate supply. So how much do we need? (click here to read more)


Fat Burning for the Serious Ironman…

Alan Couzens, MS (Sports Science)

Sept 9th, 2014

I received a bit of interest on yesterday’s tweet on the topic of Ironman metabolism shown to the left.

Most inquiries were asking what that 'ergogen..thingy' means :-) but a few of you were interested on where that balance point of the 'right amount' of fat burning for the serious Ironman athlete lies. So I figured I'd expand on that tweet and delve into the hot topic of LCHF (low carb, high fat) diets for Ironman athletes... Click here to read more....


Forget the disc wheel: Your most important 'upgrade' is the right crank!

Alan Couzens, MS (Sports Science)

Sept 3rd, 2014

I recently wrote a couple of articles on how bike geometry interacts with body geometry – specifically how your open hip angle impacts the stack and reach of your optimal bike frame. The one big factor that I left out of that equation that can have a VERY large impact on both comfort and efficiency is crank length.

Crank length is a sort of 'linch pin' in bike fit. An often ignored factor where fairly small errors can have quite large effects & an otherwise good fit can turn into a very bad one, especially if you happen to be unfortunate enough to require a smaller frame size (which will almost certainly come with a comically disproportionate crank length!).

A crank length that is too long for the athlete’s hip mobility will result in a number of compensations that, at worst lead to injury, and at best lead to high levels of discomfort during longer rides. When the crank is too long, we will see the low back excessively rounded and the hips rocking from side to side. Often the athlete will complain of hip flexor tightness. We may also see subtle but important compensations at the foot and tibia, where the athlete will internally or externally rotate in an effort to effectively 'shorten the foot' to accommodate the excessive crank length.

If the biomechanical implications don't scare you, a crank length that is on the long side will also prevent an athlete from rolling the hips forward into an effective aero position and will actually cost them a not insignificant amount of speed!

On the flipside, a crank length that is too short (a less common problem) will result in a loss in economy as the athlete is not taking the prime mover muscles through their full range of motion. Muscles are most efficient when they fully contract from their maximal resting length. Contracting from an already shortened position is less efficient. Period. Need more proof? If an individual had ongoing access to a metabolic cart and an ergometer with a vari-crank installed, and if he were so inclined, he could test the economy differences for a given crank length at a fixed wattage of say 200W over successive days. The results from those trials are below :-)

The chart shows a definitive 'sweet spot' of lowest O2 cost for a given crank length for me in the 172.5-175mm range (not coincidentally, I switched my own cranks to 172.5 on this basis). However, this is not to say that 172.5 or even a similar relative percentage of leg length is optimal for all. I have performed a similar experiment on another athlete (an elite cyclist) with quite different results. No, in my opinion, the optimal crank length is far more related to your personal hip mobility. More specifically, to keeping the pedal cycle within the optimal range of the prime mover muscles designed for the task(!) It is most determined by mobility in one key movement – hip flexion. You can assess your own via this simple test.

Lay on the floor with both legs extended & your hand placed underneath your lumbar spine to feel for any 'rounding'. Raise one knee up towards your chest and stop at the point where you notice either the knee start to drift to the side or the low back start to round out. You want to identify the angle of maximal hip flexion before any compensation creeps in. Get a spot check of the angle at this point and then make certain that you don’t exceed this angle when the hips are maximally 'closed' on the bike.

The best method of finding the right crank length for the job is via trial and error with video from the side and front taken for each crank trial. You can then look at this video and compare your closed hip angle with the uncompensated angle that you achieved in the test.

In practice, this can be a bit of a challenge because…

To help you narrow down your crank trials, I’ve prepared the following calculator.

Plug in….

Open hip angle (as described in last test)
Closed hip angle (as described above)
Seat angle – from bottom bracket to where you actually sit on the seat.
Seat height – distance along that line (in cm)
Femur length – Greater trochanter to knee line (cm)
Virtual tib length – diagonal distance from knee line to bottom of your cleat (cm).
Crank length:

It will spit out a suggested crank length rounded to the nearest 2.5mm designed to put you in a bike position that will replicate the closed hip angle given above.

If possible, I would suggest trialing cranks 5mm either side of this number and assessing your angles as described above.

You’ll see small changes in any number of variables on the calculator can have a large impact on recommended crank length. For instance…

Changes in that closed hip angle that span a very normal range of 50-60 degrees can lead to +/-10-15mm in recommended crank length! This fact alone leads to the majority of AG athletes being on the wrong crank.

You’ll also notice that the more forward the athlete is able to rotate their position, the more latitude they have with their crank selection. This presents an additional problem for many AG athletes who have a hard time rotating their hips forward and ride at a substantially shallower seat angle to the pros. This exacerbates the issue of Johnny Deskworker trying to replicate his favorite position of Torbjorn!

These realities of modern tri are simply not well accommodated in ‘off the shelf’ specs. Your average recreational cyclist just doesn’t have the same hip mobility of the competitive cyclists on whom those initial frame size vs crank length ratios were based. Therefore, it is essential to your long term comfort and economy that you 'take things into your own hands' to find the right crank length for you.

This is not to say that most athletes can't 'learn to live with' a variety of crank lengths but rather to say that the vast majority of recreational cyclists that I see are riding around with some level of dysfunction and uneconomical movement compensations that are costing them comfort, costing them watts, costing them speed & are often very easily fix-able with a few cheap 'custom upgrades'

In summary, pulling all of the recent bike fit articles together, when looking for a new ride (or upgrading your old one)….

Many folks feel pressured when buying a new bike. There’s a feeling that any extra time that the bike shop guy puts into fitting you, he’s ‘doing you a favor’. Trust me, most bike shop owners don’t have the background in biomechanics to give you a worthwhile fit (nor do most fitters for that matter!), let alone a good 15 minute fit, and you will be far better served by the ‘favor’ of a generous ‘try before you buy’ or return policy.

Buy smart,




Differences in the blood lactate curve: Ironman vs ITU

Alan Couzens, MS (Sports Science)

August 27, 2014

In a previous post, I outlined the way that I look at blood lactate data for the purposes of both setting the athlete’s training zones and identifying weaknesses in the athlete’s profile.

A great follow up question was recently raised and so I thought I would add some thoughts here. The question was “How does this analysis of strengths and weaknesses differ for short vs long course athletes?”

Below you’ll find 2 lactate curves – 1 from an elite long course (Ironman) athlete and another from a short course (ITU) athlete. Both are similar weight (low 70kg’s) and both equally accomplished over their respective distances. I would consider these curves and this data fairly typical of the differences that I see between these 2 types of athletes across the board.

Key differences.

  1. AeT (first inflection point) occurs significantly further along the curve for the Ironman athlete (70% vs 50% of peak power output). This is obviously an important training objective for the Ironman athlete and a key differentiator in training protocol.

  2. When the Ironman athlete’s curve ‘kicks’, it kicks hard! i.e. when the curve begins to turn up, it does so with a steep gradient, as opposed to the ITU athlete’s curve which is more gradual in its rise. This leads to AeT/LT/OBLA to be clustered close together Again, indicative of where the athlete distributes their training load & the relative importance (or lack thereof) of training significantly above the AeT.

  3. The ‘threshold’ point (via the modified D-Max method) is higher in the short course athlete than it is in the long course athlete. Again, clearly this point on the curve is more important to the shorter distance. An important observation: The reason that it’s further along the curve is because of the shallower gradient of all the points immediately above it. This has key training implications for short course events.

  4. The maximal numbers (both lactate and peak power output) are lower for the Ironman athlete. More than the SC guy being particularly ‘strong’ here, big volume Ironman training has a tendency to bring down maximal lactate & power numbers. I have observed a relationship between low lactate numbers and a poorer training response. Therefore, preserving some ‘top end’ even in the midst of Ironman training is, for me, an important priority.

  5. The exponent curves show that the % increase in power for a given jump in lactate is significantly greater for the short v long (~19% vs 13%) showing greater glycolytic power (and diminished lipolytic capacity) for the SC guy. Again, an important metabolic differentiator between short and long.

  6. Hopefully you will find the above data useful in monitoring your own strengths and weaknesses over the season and tailoring your training to the specific demands of your event.

    Train Smart,




    Diagnosing & Treating Your Swim Limiter: Part 1

    Alan Couzens, MS (Sports Science)

    August 18, 2014

    The guy above, Alexander Popov, represents my personal ideal of the 'textbook' freestyle stroke. I was very fortunate to spend some time during my studies apprenticing under his coach, Gennadi Touretski, who was, at the time, also the head coach of the Australian swim program at the Australian Institute of Sport. Not to put too fine a point on it, but Gennadi was a pure genius in all aspects of swim coaching – technique, physiology, you name it. However, if there was one area that he was known for, it was the emphasis on perfect technique for every single stroke swum during a session.

    What constituted perfect technique for Gennadi? 3 things…

    Others have since stolen and bastardized the concepts, but here is what they meant ‘from the horse’s mouth’.

    Rhythm – Continuity of stroke, or in Gennadi-speak, ‘minimizing intra-cycle fluctuations’. Beyond just ‘keeping the arms moving’, Gennadi emphasized the importance of moving from the propulsive phases of one arm to the next and of using the body’s natural elastic response to full effect to maintain muscular efficiency in the stroke. He called this ‘fish-like swimming’.

    Range – Through this rhythm, we want to optimize the athlete’s distance per stroke. The ‘through this rhythm’ part is important. He is not talking about gliding (in fact, the importance of keeping the arms moving was always emphasized), but rather getting the full stretch and full elastic recoil out of the most important propulsive muscles.

    Relaxation – Again, in order to move economically, the muscles cannot be fighting one another. He believed that this is the essence of a good sprinter. When we look at Alexander, he epitomizes this.

    Alex may have been a sprint swimmer, but these concepts transcend distances, and sports for that matter. A coach who ‘gets it’ and, in my opinion, has successfully translated these concepts to the world of triathlon swimming, is Paul Newsome of Swim Smooth

    In addition to emphasizing the importance of this ‘balanced triangle’ of swimming, Paul has taken the concept a step further by identifying swim ‘types’ based on relative strengths and weaknesses that tie in well with the 3 R’s concept. Meet the gang below...

    These swim types range from the apprehensive Bambino to the 'muscle it out' Arnie to the over-thinking Over-Glider, all the way up to the balanced 'Mr. Smooth', typified by our friend Mr Popov in the video above

    At the risk of putting words into Paul’s mouth, here is how I see the interaction between Paul’s swim types and Gennadi’s 3R’s…

    This swim ‘typing’ is an incredibly powerful tool when it comes to drill selection. There is a growing trend, particularly in triathlon swimming, to bash drills, with the prevailing thought being “…well, Open Water swimmers sure don’t have those pretty strokes that (some) pool swimmers have, therefore drills are a waste of time”. In my opinion, this attitude stems from a lack of understanding of the purpose of specific drills. If you’re not sure what outcome you are shooting for from a given exercise then, yes, that exercise is probably a waste of time!

    So, here is what I am shooting for with the respective groups of drills…

    Rhythm drills – Neuromuscular re-programming. The only way for the nervous system to become conditioned to a new movement is to practice that movement. If you think about it, this borders on a koan :-) But, if we get tricky, there are ways to force us to become accustomed to new movement patterns. This is the essence of rhythm drills. For example, Alexander would use a towing system attached to the roof of the A.I.S. to pull him at a speed slightly beyond current world record pace (& consequently force him to rate a little quicker than he was accustomed). You might not have access to this piece of equipment but, if rhythm is a limiter, there are other tricks that we can use that I will outline in my next article.

    Range drills – In addition to the neuromuscular elements mentioned above, adopting a particular position demands that the athlete have the mobility to get in that particular position(!) If you grew up swimming & you add up all of those milliseconds that your developing body spent in a catch or streamline position, you have a good chunk of time! If you did not grow up swimming and your body is no longer ‘developing’ (at least not in the good way :-), you have some ground to make up! To put this time in perspective, Williams (1998) found that it takes more than 30min of end range stretching per joint, per day to merely prevent normal sarcomere loss! Range drills are an excellent way of combining these 2 objectives of ‘learning’ optimal swim positions and spending a lot of time in ‘end range’. At the very least, please TIGHT streamline off EVERY wall. It all adds up!

    Relaxation Drills – If you’re feeling like you’re on the verge of drowning, relaxation can be tough! :-) Seriously, there are 2 primal instincts that can come into play to seriously mess with your stroke:

    1. Holding your breath when your face is in the water
    2. Fighting to stay on top of the water.

    If you lack relaxation, you won’t have the foundation for building rhythm or range so the most important objective of all is a simple one – become relaxed & ‘at one with’ the water. It can take a lot to overcome those primal instincts, especially for some folks who have a bad experience buried deep in their cerebellum so very simple drills that separate breathing and body position from propulsion can be very high value.

    This leaves us with a lot of potential drills – 3 different categories, with a whole bunch of specific drills within them. Looks as though I failed again in my mission of simplifying things :-) Maybe Paul can help me. Let’s return to the notion of ‘swim typing’ here. Not only can identifying your particular limiters help you to identify the best drills for you. It can also stop you from doing drills that will actually make things worse!

    If you are an overglider who has great range of stroke but poor rhythm and you spend hour upon hour with your arm sitting in your front quadrant, is that going to improve the situation? Similarly, if you’re a beginner who is anxious in the water and rating like crazy just to avoid sinking, are stroke rate drills your best answer? Obviously, the answer to both is no & so we are left with a mission – identify your own personal limiter and then select the drills that best fit.

    Your homework is to head on over to ,take the quiz (along with the other assessment techniques) to identify your particular type (& subsequent limiters). In part 2, I’ll give you my own take on the best drill prescription to ‘treat what ails you’.

    Train smart!




    Diagnosing & Treating Your Swim Limiter: Part 2

    Alan Couzens, MS (Sports Science)

    August 25, 2014

    In my last post, I gave an introduction to the 3 key technical swim limiters that I see among triathletes. Namely, Rhythm, Range and Relaxation. I suggested that, if you are serious about improving your swim this season, that it is essential to identify which of these are holding you back. Finally, I pointed your over to Swim Smooth for a simple but powerful 'diagnostic' tool to begin to identify your current limiter.

    In this article, I'm going to delve a little more into the practicalities of how to go about diagnosing your own swim limiter. I'll introduce you to a simple test that you can use to not only help to identify your own weaknesses but also to help you track improvement in these areas over time.

    Before we get into the fun stuff, a quick story that will help to better illustrate some of the principles of improving your limiter. The guy above is Michael Klim. Klim was also training at the Australian Institute of Sport with Alex Popov during my stay. At the time, Klim was still a relatively young guy and an 'up and comer' on the Aussie swim scene. I had seen him swim a few times before at various meets and his stroke 'looked' like most of the other top Aussies at the time, i.e. very 'rangey' with a heavy kick. At that time, he was a very good flyer and a fair 200 freestyler. However, the first time that I saw him at the A.I.S., I saw a very different swimmer. Long gone was the semi catch up, heavy kick stroke and in its place was a strong, very pull dominant power stroke. Gennadi had taken one look at Klim when he arrived at the A.I.S. and decided that as a strong, muscular guy, his stroke was not geared to his strength & so, after identifying that limiter, he completely rebuilt it around the power stroke to which Klim was most naturally suited and Klim became a truly world class sprinter who often rivaled the (very different) smooth stroking Alexander. The moral of the story is that a lot of good can come from training against preference and exploring the weaker areas of your stroke. Who knows, what you thought was a weakness may actually turn out to be a natural strength!

    Below you'll find a diagnostic tool to help you better identify your own limiter. It's based on a couple of very simple but important relationships that we see between patterns in speed and stroke length as explained below...

    1. The relationship between an increase in effort and an increase in speed

    There is an interesting pattern related to the skill level of a swimmer that was first identified by Holmer way back in the 70's. That pattern is this...

    If we look at the energy expenditure of skilled and unskilled swimmers, not only do we see skilled swimmers expend less energy for a given speed but also the rate of change in energy expenditure for a given pace increase is significantly less.

    This relationship (with the actual data from that study) is shown in the chart below...

    As you can see, for a given increase in energy output (VO2), the skilled swimmer gets a lot more speed 'bang' for their energy 'buck'. This is due to a very basic rule of hyrdrodynamics - the faster you go, the more drag increases (exponentially) and the more impact a poor technique will have. Knowing the above, if we test 2 or more effort levels and we monitor the pace jump between these levels, it can tell us a lot about the skill level of the swimmer.

    2. The relationship between an increase in effort and an increase in stroke count

    Similarly, the way that stroke count changes with increasing effort, tells us a lot about the 'type' of swimmer that we are working with. Whether they are able to..

    This relationship tells the savvy coach a lot about relative pull v kick dominance, along with potential strengths, weaknesses and the most advantageous technical areas of immediate focus

    If we put these 2 simple metrics together, we have a plethora of good information to help us better understand the strengths and weaknesses of any swimmer

    So let's get down to the fun stuff! You may have seen the training zone calculator that I recently added to the EC site. In that article I outlined my preferred method of identifying swim zones - via a narrow descend 5x400m set (from easy to moderate). With a slight modification, this set can also tell us a lot about the technical elements of the swimmer -- their swim type and also their relative strengths and weaknesses across the '3 Rs'.

    Below, you'll find a calculator based on that 5x400m set. To use it, simply plug in your height (in cm) along with the pace and stroke count data from the 2 400's that best line up with your 'steady' and 'moderate' heart rate zones....

    Height (cm)

    SteadyStroke count (25m)
    ModerateStroke count (25m)

    The calculator will do some 'behind the scenes' math to look at the relationship between your increase in pace (with an increase in physiological effort) along with any increase or decrease in stroke length for a given physiological effort to better quantify your own rhythm, range and relaxation in the water. It will then spit out a ranking (out of 10) for each, shown on the bar chart below




    Overall Swim Score: 0/30

    How to interpret the test

    If you score below 7 in any of the 3, consider it a potential limiter worthy of some attention. You may find that you have more than one limiter under the 7 mark. This simply indicates that you have a lot of upside on the technical side of things & will benefit quickly from a dedicated technical focus block! On the flipside, if you're 'high and balanced' across all 3, bad news for you: Your route to improvement is fitness, in other words - YARDS! :-) For additional context, and a bit of a clue on where this is headed for each of the limiters, you can then refer back to my take on how these limiters tie in to Swim Smooth's swimtypes

    This algorithm is just a high tech version of the old 'swim golf' game -- where you take your speed and your stroke count and add them together for a total score. While that concept is a useful one, the weighting isn't fair and can lead to some suboptimal messages regarding optimal technique. E.g. A normal 25m sprint for me might be 14s and 15 strokes for a score of 29 but if I kick a 25 hard on my side and don't take any strokes, I could pretty comfortable do it in 22s or so, leading to a score of 22+0 = 22!. While this is an extreme example, you can see the danger in putting too much emphasis on this (non weighted) metric

    Once you are aware of (& able to somewhat quantify) your limiters, you can have a much more focused plan of attack to the technical aspect of your swim training. Rather than having a myriad of drills that may or may not work against your limiter, you can stick to a handful of drills that are specifically designed to address your personal weakpoints. Furthermore, you can use the calculator above to help to better quantify whether you're improving and in what direction you're improving. Sometimes it's a bit like a game of spinning plates. If you spend too much time trying to improve your weakness, you may wind up losing some of your natural strengths so it is important to keep both in mind and in view. Put another way, you don't want your total score to go down even if your limiter is improving!

    For you personally, that means that we want to focus strongly on your weakness while also making sure we don't lose your natural strength  In my next article in the series we'll look at what a block of technique training might look like for you, along with some specific drill sets designed to nudge up your weakness Until then...

    Train Smart




    The hidden cost of an overly aggressive bike position

    Alan Couzens, MS (Sports Science)

    Aug 7, 2014

    With the 2015 bikes hitting the market, many Ironfolk will be ‘looking to upgrade’. Usually this means better materials, sleeker lines, hiding more ‘stuff’ &, above all else, more aggressive geometry. After all, nothing looks better rolling through transition than a bike with full aero set up and a huge drop. Big drop = low frontal area = this dude is serious about laying down a fast bike split!

    Well, there is one element of that equation that is missing – big drop + holding the position for 5ish hours = fast bike split!

    While a big drop may look cool coming out of T1, it looks a whole lot less cool when the athlete is sitting up riding the bull horns for the second half of the race. Not only does it look a little ridiculous, it’s also slow. How slow?

    When an athlete moves from an aggressive aero position to ‘sitting up’ on the bull horns, he can increase his trunk angle (the angle from the trochanter to the acromion) by 15-20 degrees as shown in the contrasting pics shown below.

    Aggressive aero

    Sitting up

    As this neat chart from one of the experts in the field of bicycle aerodynamics, Professor Daniel Heil, illustrates, this increase in trunk angle can reduce ground speed for a given power output by 10% or more.

    In other words, that 5hr split, now becomes a 5:30 split! OK, this may be a little extreme, our athlete is going to want to at least clear the crowds before he starts to sit up ;-), but I would suggest that it is quite common for at least the back half of the mid-front pack bike splits to include a good amount of ‘sitting up’. Based on what I’ve seen, there are a lot of people in that mid-front pack who are leaving 10-15min out there on the course purely because they bit off a little more than they could chew when dialing in their bike fit.

    To be fair, it’s not entirely the athlete’s fault, nor is it entirely, the fitter's fault. There is a trickle down effect that comes from pro cycling that ignores the fact that a cycling TT is about 20% of the duration of an Ironman split. In terms of the market, this means that the more expensive bikes, the type ridden by the pro tour teams typically have shorter head tubes that result in a position that borders on intolerable for 180K, at least for ‘Joe Officeworker’.This fact is worth bearing in mind when selecting a new frame. Often the geometry of the ‘one level down’ bikes is far better suited to long course tri than the TT flagship rigs that make up our ‘dream bike’.

    To further illustrate with some numbers, typical trunk angles for ‘top notch’ pro cyclists on TT bikes are in the range of 15-20 degrees. Consequently, the geometry of the best TT machines is built around accommodating these positions. Elite long course triathletes, who are more often in the 20-25 degree range can make these frames work, but for the majority of the age-group field – folks who – let’s be honest – might be a little more ‘Tin Man’ than ‘Gumby’, optimal trunk angles, i.e. angles that don’t result in dysfunctional compensation, are often closer to (and sometimes beyond) 30 degrees. The differences here tie in to the natural differences in hip mobility that we see between youngish guys who ride their bike 6hrs a day and your average middle-age office worker that spends 8+ hrs a day with his hips flexed to 90 degrees.

    Basically, the spectrum of mobility (especially through the hips/hamstrings) across the gamut of athletes participating in Ironman races is incredibly broad, while the geometry of TT bikes is not. These differences should be accounted for when fitting the athlete/selecting the right bike!

    The ‘cost’ of not paying attention to these differences and maxing the hips out is paid by 3 other body parts..

    So, how do we go about identifying our own, individual, 'just right' amount of drop?

    A great starting point for identifying just how aggressive your personal position should be comes from a simple hip mobility test called the ‘waiters bow’ explained succinctly in this article/demo from Ironmaven

    Using a goniometer measure the most acute angle that you achieve in the test (before lumbar compensation creeps in) and plug that number, along with your body dimensions and your seat angle (angle from BB to actual sit point on the saddle) into the calculator below and it will spit out an approximate trunk angle and a good recommended starting point for your saddle to aero pad vertical drop (negative meaning pads are above saddle).

    Drop Calculator

    Hip Angle (degrees)
    Seat Angle (degrees)
    Torso Length (cm)
    Upper Arm Length (cm)
    Trunk Angle (degrees)
    Drop (cm)

    If you run the numbers, you’ll see that the difference in recommended drop between a ‘tinman’ with limited hip mobility (hip flex of >110 deg) and a ‘gumby’ with high levels of mobility (<90 deg) can, for an average sized cyclist, amount to a difference of 10-20cm! The bulk of this difference should be absorbed within the length of the headtube, as having a steerer tube that is too long & full of a gajillion spacers can have some seriously deleterious effects on handling (as well as being just plain dangerous!). For these reasons, most manufacturers will recommend a maximum of ~7-8cm of steerer tube exposure above the headset. When combined, these 2 factors alone, can significantly narrow your bike selection.

    Some manufacturers are beginning to recognize the different demands in bike geometry needed for age group Ironman cycling vs pro TT racing and are building ‘taller stack’ versions of their TT bikes (e.g. Felt's new B series bikes). However, by and large, the market is still largely made up of the TT bikes of pro cycling. While elite IM athletes may be able to find the extra 10cm or so of stack in spacers, stem and pads to make these frames work, finding the 20 cm that puts the bulk of the AG field into an appropriately comfortable position can be, frankly, prohibitive on the flagship rides.

    This is not to say that your average ‘Joe Age-grouper’ won’t be able to sit on these bikes and maybe even look OK for 15 minutes in the comfort of the bike shop (especially to the bike shop guy who’s about to make a $5000 sale :-), but without the hip mobility of guys that do this as their job, they will accommodate the overly aggressive position more in their back, neck & taint(!) leading to discomfort if held for any length of time.

    In summary, tight muscles will get even tighter & things will get less comfortable over the course of an IM bike leg for all levels of athlete. Whatever your natural mobility levels may be, in order to avoid the dreaded ‘sit up’ you need a little bit of reserve in your position that takes this into account. Be sure to select a bike that is appropriately conservative enough to allow you some room to move in your back (forward flexion) and your neck (extension) and a little bit of room to ‘wiggle’ on the saddle. This may mean scaling back a tad on your dream ride but an aero you trumps an aero bike any day of the week.

    Buy smart!


    Update: Aug 11, 2014

    Had a couple of folks ask a true ‘nitty gritty’ question in response to my “cost of an overly aggressive bike fit” piece… “OK, so what bike should I buy?” Actually, more specifically – “I got this recommended trunk angle from your test. How much ‘stack’ should my ideal bike have?”

    ‘Stack’ and ‘Reach’ are two concepts introduced by fit guru Dan Empfield. They break a bike fit down into X and Y coordinates, with ‘stack’ being the number that represents the vertical component to your frame & 'reach' being the number that represents the horizontal component. You can read more about them here.

    Specifically, stack is the vertical distance from the bike’s bottom bracket to the very top of its head tube, while reach is the horizontal distance between the same 2 points.

    You’ll remember from my last article that I suggested that there is a maximal amount of additional distance above the frame’s natural head tube stack that is safe in terms of handling and structural integrity of the fork. Specifically, this is in the 7-8cm range. This includes spacers, stem and headset cap. With an angled stem and some risers under the aero pads, we can add a little more to this. But, all told, when we do the (trigonometric) math, the maximal additional vertical stack that we’re working with is (at most) ~17cm (vertically from the top of the frame to the pads).

    Therefore, since this is relatively fixed, if we know the athlete’s seat height & the athlete’s ideal drop from seat to pads, we can begin to identify a good range for frame stack.

    I built up a simple calculator below that takes the above into account and spits out a minimal frame stack (for a given drop/level of hip mobility).

    Stack and Reach Calculator

    VERTICAL Seat height (to BB)cm
    Drop (from calc above)cm
    Pad Heightcm
    Max stem/pad stack17cm
    Min frame

    Important note regarding the above: Many of the 'flagship' TT bikes now come with integrated front ends that can significantly limit the total rise available above the headtube to far less than the ~17cm mentioned above. This is important to note when looking at the true available pad stack with these bikes & in my opinion, is yet another reason that many AGers will fare better buying one level down

    A less aggressive fit will have a similar effect on the optimal 'reach' of the frame. The more conservative the trunk angle, the shorter the 'cockpit' (the distance between the trochanter and the elbow) becomes. With a little bit of trig, we can roughly quantify the change to this distance for different trunk angles to put you in the 'ballpark' for a frame that will work for you.

    Breaking it down, this 'cockpit' is made up of 3 parts - setback (the distance that you sit behind the bottom bracket), reach (the distance between the bottom bracket and the headtube) and stem (the horizontal distance between the headtube and your aero pads). Only 1 of these is even somewhat adjustable so it is important that you get the 2 components that make up the frame at least close to the mark!

    Based on the numbers you put in above, your personal setback is ~cm. Note: If I have one criticism of Dan's system, it would be that it ignores this number (assuming that tri bikes generally have similar seat angles) and only looks at what is in front of the bottom bracket. While this is a relatively fair assumption, if you are comparing 2 bikes with different seat angles, this should be taken into account.

    Your horizontal stem length is the one factor that is somewhat adjustable, but keep in mind that small adjustments will have a relatively large impact on bike handling, as explained in this great article on the subject by Dan. In practice, when we factor in relatively normal levels of stem length and inclination, we're limited to a pretty narrow horizontal range of 5-10cm beyond the line of the headtube.

    Adding all of this together, if we take your total cockpit of (calculated from the numbers above) and take away the setback and the stem extension, we're left with an optimal frame reach for you in the range of ~ to cm

    Once you have an idea of the 'ballpark' frame stack/reach you’re looking for, you can check out Slowtwitch’s trusty stack/reach database to narrow down your bike search.

    Happy shopping….



    Know your enemy: Ironman Boulder

    Alan Couzens, MS (Sports Science)

    July 17, 2014

    “If you know the enemy and know yourself, you need not fear the result of a hundred battles”
    - Sun Tzu

    We (Endurance Corner) recently hosted a race prep camp for the coming inaugural Ironman Boulder. With the race course fresh in my mind (and legs), I figured now would be a good time to put together a quick synopsis of what athletes should expect & how they should strategically play the race.

    The swim is a simple 1 loop counterclockwise ‘triangle’ course in the waters of the Boulder reservoir. The only real significant feature of the swim is the bright sun that will hit you when swimming in the initial North East leg of the swim. This could make the initial turn buoy a little hard to spot so try to identify a larger landmark to the North at the start of the swim. It could also make sighting to the left a little challenging on the way back so be sure to have another good landmark at the swim finish. Tinted goggles are a must. Also, buoys will be on your left so get comfortable with some left side breathing.

    The bike course can be basically broken up into 3 sections as shown on the elevation chart below.

    Grades of 2% or greater are highlighted so that you can see how they are distributed across the course. As you can see, the most sustained uphill sections occur deep into the 180K. In terms of optimally pacing your race, a simple rule of thumb is to go ‘1 zone up’ on grades of 2% or more, ‘2 zones up’ on grades of 5% or more and the opposite of this for the downhills, i.e. on a 2% downhill, due to the higher air speed, athletes are best served in a speed:energy output perspective going easier than their average output. While, on grades of 2% or more, when air speeds are lower, athletes should be pushing one zone up from their average watts. For the Boulder course, with the most sustained grades occurring late, this makes a 'negative power split' strategy especially optimal!

    Section 1: “Steady comfort” (Transition to the end of highway 36).
    This is a rolling net uphill, with the longest stretch of consistent gain in the whole race. That said, grades, particularly in the early stages are not obvious. In other words, it is one of those phases where speed is slow & the athlete has something to push against. This coupled with early race adrenaline will lead many athletes to open up with an overly aggressive strategy. While I am generally a fan of “going fast when the race is slow”, if there is an exception to this rule, it is at the very beginning of the race, when heart rates are typically still high from the swim/T1 and the athlete is looking to settle things down in order to get ahead on nutrition. With this in mind, I consider this phase of the race a ‘steady’ (Zone 2) ‘get comfortable’ period. There is one additional nasty grade (not shown) in this section that has athletes rolling down and back up St. Vrain as a short distance tack on. This grade is significant and, with it occurring early in the race, most athletes will likely spike their heart rate/power significantly. If you are passing folks on this climb, you’re probably pacing sub-optimally. Temperatures will likely be cool to pleasant in the early bike but will warm up quickly. Once heart rates are settled, use this period to get ahead on hydration.

    Section 2: “Easy Aero” (66 to CR 13).
    This is the fastest section of the course, a net downhill. Speeds will be high and athletes will feel good. The temptation at this point will be to be of the mindset “this is easy, I’m going to crush this bike split”. Don’t be fooled. The hard section of the course is still to come. Enjoy the speed that you are getting at relatively easy output, but in the words of my buddy, Justin – “Don’t go looking for work”. It will come! From a pacing perspective, most AGers will be best served by sticking to their easy (Zone 1) power/HR band for the bulk of this section, with a focus on staying aero and (legally) surfing those competitors who are pacing inappropriately and rolling past. Both average heart rate and power should be at the lowest points of the bike at the completion of this section, giving you plenty of room to elevate in the closing stretches. There is one scenic short climb that is an enjoyable ‘stretch break’ during this section from km 45-50 along CR12. This is the most scenic section of the course Take a look around and enjoy it. There are some sustained periods of less exciting scenery ahead

    Section 3: CR 13 to T2 (The work begins!)
    This is the section of the course that I live closest to and I have had my 'hundred battles' on it - some won, most lost. It is deceptively difficult, especially late in a long ride. Despite the relatively low net elevation gain of the course, it is not a ‘flat’ course like Florida or Arizona. Nor is it a momentum rolling course like Louisville. You are basically rolling slightly down (heading away from the mtns) or slightly up (heading towards the mtns) the whole time. From 100k to the finish, you’re rolling up! The road is pushing against you fairly consistently during this period & you will want the legs to push back! This is the section of the course where athletes who have saved sufficient energy to draw on some Zone 3 (Moderately-Hard) will be rewarded. This Zone 3+ effort will be a necessity for the bulk of athletes on the steepest pitch of the course, as the athletes turn off Hwy 52 and head to lookout road. You will want some legs for this period of the race. Following this, there is a relatively flat roll through downtown Boulder to the high school where you will begin the run.

    Winds typically are Easterly and pick up through the day. The exception would be if an early storm blows in over the mountains. If this is the case, it generally leads to Westerly winds that are quite strong and would be blowing straight at you as you roll back into town along highway 52. Prepare yourself for this possibility. If you are already ‘fragile’ at this point, It will make for a very tough day!

    The general pattern of the 2 loop run course is similar to the bike – slight downhill as the athletes head away from the mountains, followed by a slight uphill as athletes head back towards the mtns. Athletes will enjoy the slight downhill start as they roll out of Boulder high school and along the cool waters of the Boulder creek. This pleasant phase is short lived, however, as athletes will make a turn off the creek path to begin the first of the ‘tack ons’ that race organizers added following the Boulder floods. This first tack on (~3 to 8K) is a slight net uphill grade on the way out that is not particularly obvious. It just ‘feels’ like work after coming off the pleasant downhill of the path. Athletes will likely ‘over cook’ this part of the course as they start to feel as though they are moving too slow following the grade assisted section of the BCP.

    Runners then roll back towards the path for a short stretch before beginning the only significant hill in the course as they climb the foothills parkway overpass. This is the most exposed, least ‘pleasant’ section of the course. Many athletes will be well served to add a walk break at this point. Following the overpass, the athletes roll down Pearl Parkway on a net downhill to the turn around. Following the turnaround, the work begins!

    From ~11K to ~18K (33 to 40K on lap 2) is the longest consistent uphill stretch as athletes head back ‘up the creek’. This isn’t so much a hill as a ‘slow section’ of the course. It’s sheltered and cooler than the more exposed sections, but from a pace perspective, just be prepared to see slower paces on this section of the course. This long period of ‘feeling slow’ may be tough on those athletes that have paced sub-optimally to that point, and this is the perfect section to make a lot of passes if you’re feeling good. This is especially the case on lap 2. Passes here will stick! The path winds and twists and when passes are made it will quickly be a case of “out of sight, out of mind”. Running to pace will be particularly demoralizing on a course like this. With the grade differentials and the impact of altitude, I would advise all athletes to pay close attention to heart rate on both bike and run.

    The grade progressively increases a little more as athletes approach the 2nd turn around at Eben G Fine Park. This would be another good spot for a well placed walk break. Following this turnaround, the athlete hits the fastest section of the course as they roll downhill back to the starting point at Boulder High School, before beginning lap 2. You will want to have the legs to run here with good cadence for an extended period of time. While the speed differential between running hard and ‘turning the legs over’ won’t be that great, the difference between walking and running here will be large. The course is almost all concrete and with the grades, could be tough on the legs & feet. Be sure to train this aspect with some uphill/downhill running.

    In many ways, this course is a perfect example of a course where ‘back end loading’ your effort is rewarded. The toughest parts of the course will be in the latter sections of both the bike and run. Arriving at these points ‘ready to work’, will be rewarded.

    For our Endurance Corner profile of Ironman Boulder from local pro, Justin Daerr, click here

    To hear Justin, Gordo and I chat about some of the challenges of racing at altitude along with some more course specifics, click here

    Race smart!



    Carbohydrate Loading for Ironman Athletes.

    Alan Couzens, MS (Sports Science)

    May 30, 2014

    In my previous post, I weighed in a little on the LCHF debate. As I outlined in the post, valid arguments can certainly be made for moderating the carbohydrate intake during the bulk of the training phase for most athletes. However, as we move from training to taper, different considerations emerge that will have impact on the optimal pre-race diet for the endurance athlete.

    Studies have consistently shown a strong relationship between starting CHO stores and time to fatigue at submaximal intensities. For example, Balsom et al., (1999) found a 50% decrease in time to fatigue when subjects began an exercise test with a 50% reduction in glycogen stores. This almost linear relationship between starting glycogen stores and time to fatigue has been observed in numerous studies. Therefore, a key objective heading into your A-Race is to maximize this adaptation. The good news is that it doesn’t take a lot of time or effort to maximize this adaptation. However, it does require doing things a little bit differently to your normal training and nutritional routine and perhaps a little different to a normal taper routine for a shorter distance athlete.

    Ironman legend, Torbjorn Sindballe comments on some of the differences here...

    “ If I only did shorter sessions for the few weeks leading into a race, I often felt super fresh but lost my momentum after hour three or four in the race. To combat this, I implemented a big rest phase to reduce fatigue several weeks before a big race and then did a series of more normal training sessions in the weeks leading up to the race”


    What he’s referring to is a very real physiological phenomenon of metabolic detraining. While, most physiological adaptations can be sustained on relatively minimal volume for 3-4 weeks, if an athlete does not ‘challenge’ the ability to hold on to larger than normal glycogen stores, it is an adaptation that is lost rather quickly. A typical rate of ‘metabolic detraining’ is shown in the chart below (data from Casey et al., 1995).

    In the absence of sufficient stimuli, the body will lose 10% of its glycogen stores within 2 weeks (more if the lack of long rides extends into other weeks!) & you will lose 10% or more from your time to fatigue! For this reason, including regular moderately long sessions, even relatively close to an Ironman, is a very worthwhile strategy for the serious Ironman athlete, as suggested by Torbjorn. However, it is not just the shift in race week training that will enable you to elevate your glycogen levels to new highs. The training must be accompanied by a similarly appropriate nutritional strategy.

    To increase your body’s receptiveness to storing glycogen, demands a little bit of a departure from a normal taper routine in both training and nutrition. Here is what I suggest for the long course athlete…