In the previous post about heat acclimation, I talked a bit about the effect of heat on performance (bad) and the effects of acclimation on this (good). The most meaningful physiological adaptation that occurs is an increase in plasma volume (a lot like adding more radiator fluid to a car). However, there are some other adaptations that occur – changes in sweat rate, changes in sweat sodium concentration and changes in core resting temperature, to name a few. The various adaptations occur with different amounts of acclimatization. Here’s a graphical representation of the times over which an athlete can gain these benefits:

As I mentioned in the last post, the benefits of heat acclimation decay rapidly if you do not maintain heat exposure. Estimates vary, but it’s possible that you could lose half of the benefit in 10 days without ongoing heat exposure. This raises some logistical problems for athletes living in cold environments who are attempting to acclimate for a hot weather event. To benefit maximally from acclimatization, the heat training sessions should occur as close as possible to the event. That seems pretty straight forward. The problem is that acclimation is quite physically demanding, and most athletes attempt to taper in the week(s) prior to a big race. So, if you want to acclimatize optimally, it needs to occur during your taper – which may cause overtraining, or at least minimize the benefits of tapering.

To address this problem for my own racing, I worked with the exercise physiologists at Simon Fraser University’s Environmental Physiology Unit. They put together a low intensity heat acclimation program specifically tailored to my needs (the Marathon des Sables in Morocco). In brief, I ran on a treadmill at 60% VO2max for 45-75min for 9 sessions. The first 3 sessions were at 35C and the next 5 were at 45C. The last (9th) session occurred at 35C again – this allowed us to compare my physiological data from the first and the last sessions. Here are some of the data we recorded. I think that you will agree that some real benefits were seen. (This data was makde public in abstract form at the 2009 CSEP meeting).

The Borg Scale above is used to assess subjective overall effort – I clearly felt that the same spped was easier in the heat after 9 days. The “thermal comfort score” below shows that I was bothered less by the heat after acclimation.

One of the most important ways to prevent heat injuries, and to maintain performance in extremely hot environments is to drink adequate amounts of fluid. This seems obvious, but it is actually suprisingly hard to do this if you are focussing on running. I think that one of the most useful benefits (for me – not living somewhere hot) was learning to drink earlier and more frequently. That I learned this lesson is well demonstred in the graph of fluid balances on day 1 and 9 below.

Finally, what happened to heart rate? As you can see below, my heart rate at the same speed and temperature decreased by about 9% – a very significant improvement. Now, it didn’t get as low as what I would expect it to be in “normal temps”, but the improvement was significant, and could be expected to translate into a tangible benefit in competition.

So, in my experience, heat acclimation based on well documented scientific principles, can give athletes a significant performance enhancement in hot environments. It is important to recognize the effect of acclimation on the tapering period, and plan accordingly.

•  Armstrong LE, Maresh CM. The induction and decay of heat acclimatisation in trained athletes. Sports Medicine 1991;12(5):302-12.

• ME Clegg, S Ghaffari, ML Walsh, W Henderson and MD White.  A case study: Acclimation for the Marathon des Sables. Canadian Society for Exercise Physiology, Vancouver 2009.

This spring, I had hoped to run in the Libyan Challenge or one of the adventure races happening in South America. The arrival of EnduranceBaby (!) messed up that timing, but I will be competing (actually more likely just participating, given how training has been this spring) in a fantastic multiday race in southwestern France. The TransAq is a 6 day self sufficiency race similar in concept to the Marathon des Sables. The total distance is around 250km with terrain that varies from sandy (beaches) to forest trails.

                                                                                                                                                                                                                                                   It’s a relatively small race, with a loyal local following, and I’m looking forward to some great running, as well as getting to bone up on my atrocious French.For those of you interested in a first multiday race, or if you’re looking for something a bit easier on the budget than something like the MdS, this looks like a great option. I’ve corresponded a lot with the race director Gerard, who seems affable and expert.

It seems a bit funny to be talking about heat acclimation in March, given that most us are still trying to decide if we should risk running in the snow/sleet/rain. However, over the next several weeks the Marathon des Sables, the Libyan Challenge (cancelled this year) and several adventure and stage races in Central and South America will get underway. All of these races take place in hot environments. A question that often comes up for competitors, particularly if they live somewhere that is currently in the grip of winter/spring, is “how can I prepare for the effects of heat and humidity”?

There is little doubt that exercise performance is impaired in hot environments. While the effect of heat on performance varies with the sport (for example, less effect on cycling than running), there is a great deal of empirical data showing a link between  ambient temperature and performance. Various authors have suggested performance impairments of between 1.6 and 3% in marathon times for every 5C above 12C. Below is an interesting table from a paper by  Scot Montain and colleagues at the US Army Research Institute of Environmental Medicine illustrates the relationship between elite marathoner finishing times and course temperature in the New York City Marathon.

The effect seems to be less dramatic for faster runners. The following table from a 2007 paper by Matthew Ely demonstrates this nicely:

Why are we slower in hot conditions? There are a variety of proposed mechanisms, but the one that is most widely accepted is based on cardiac output limitations.

When we exercise, we produce a great deal of heat. One of the principle ways that we get rid of this excess heat is through sweating (evaporative heat loss), as well as conduction and radiation of heat from our skin. To achieve this, our bodies have to send a considerable amount of blood to the skin. This blood is therefore not available to perfuse working muscles and deliver oxygen to them. So a portion of our blood volume is essentially no longer able to participate in oxygen delivery and energy formation in our exercising muscles. The greater the amount of heat that we need to dissipate, the greater the proportion of blood that is diverted to the skin (up to a point – this can’t increase forever).

What is necessary for cooling isn’t the haemoglobin (the red blood cells in blood) but the plasma, which is essentially water with a number of different proteins and electrolytes in it. However, your body can’t separate the red cells (which are the oxygen carriers) from the plasma – they all go along for the ride to the skin. 

If it is plasma that is the essential cooling component, is it possible to improve this problem by increasing our total plasma volume? Yes, and that is exactly what happens as we adapt to heat over time. Whether you acclimate naturally to higher temperatures over the course of a season, or in a heat chamber, the most significant change that occurs is an increase in plasma volume. Other things occur as well (such as changes in sweat sodium concentration, resting core temperature and heart rate) but plasma volume expansion is the key. After extensive acclimatization, plasma volume can have expanded by as much as 2 litres!

This may explain why the fittest athletes adapt to heat stress more quickly than the less fit. One of the by-products of endurance training (especially at high intensities) is an increase in plasma volume. So just by training hard, you can derive some amount of heat acclimation. What about specifically training in a hot environment to improve performance in a hot race? There is extensive evidence that it is possible to improve our performance in hot environments by training in similar conditions prior to competition. Several studies have demonstrated performance improvements in terms of maximum work rate, perceived exertion, time to failure at submaximal work rates, and time to complete a specific distance.

The work needed to achieve this benefit is reasonable. Most laboratory based heat acclimation protocols have athletes sped about 1 hour a day in a heat chamber for 7-10 days. Importantly, this needs to occur as close to the time of the competition as possible, as the adaptations conferred by acclimation decay rapidly without ongoing exposure. So there’s no point in spending 2 weeks in a heat chamber a month before the race – the effects will decay in 1-3 weeks.

In the next post, I’ll talk a bit more about the specific protocols that can be used, and outline what I did to get ready for the Marathon des Sables – a multiday footrace through the Sahara.

• S Montain, M Ely and S Cheuvront. Marathon Performance in Thermally Stressing Conditions. Sports Med 2007; 37 (4-5): 320-323

• Ely MR, Cheuvront SN, Roberts WO, et al. Impact of weather on marathon-running performance. Med Sci Sports Exerc 2007; 39 (3): 487-93

• Y Kobayashi , Y Ando , S Takeuchi , K Takemura , N Okuda , Y Isobe , S Takaba,  K  Ohara . Effects of Heat Acclimation of Distance Runners in a Moderately Hot Environment Eur J Appl Physiol 45, 189-198 (1980)

I’m still putting together a post on some specific strength and plyometric drills, but I thought some of you might be interested in a couple of websites that I follow. Perhaps they’ll give you something to think about during long easy runs or recovery sessions.

The Canadian Athletics Coaching Centre hosts a site through the University of Alberta that has dozens of outstanding podcasts, written documents and videos from world class coaches. Most of them are free (some are pay per view). I highly recommend them to anyone interested in the current cutting edge in coaching theory and practice. Not all of it is applicable to endurance sports (not sure that javelin training will ever be part of my regimen), but much is. Click on the pic below and go to the “media on demand” section.

The second link is unrelated to running or endurance sports. Ted.com is a fantastic forum for learning about new ideas (or seeing things you are familiar with in a new light). It might open your eyes to issues going on around all of us that you had not noticed. It might upset you. It won’t bore you though.

Food for thought and tools for becoming a better citizen of our planet (again, click the pic).

In my last post I outlined some of the evidence for ancillary strength training for runners. I think that there is clear evidence that lower body strength exercises can improve running economy (and therefore performance) in well trained runners. I received two interesting email in response to this post that I thought I would expand upon.

The first email asked if it was better to add weight training or more running volume to improve performance. This is an excellent question, as it gets to the heart of many “cross-training” myths. Many people feel that they can cross train their way to better running. I think that cross training in other sports is very beneficial, particularly in that it can allow development of stabilizing muscles, avoids developing the not 100% attractive “runner’s physique”, prevents burnout and is, well, …fun! However, there is no doubt that the strongest predictor of distance running improvement is volume of running. So if you can increase your volume further (without injury or burnout), this is probably the way to go. But… if you have hit the point where more volume leads to injury, excessive recovery time, or if performance has plateaued, the adding non-running training seems prudent. I will (hopefully) expand on the evidence around training volume and performance in a future post.

The second question asked about plyometric training. Plyometrics is a system of exercises that uses rapid, explosive movements to improve power. Examples include hopping, bounding, box jumps and so on. The mechanism by which plyometric training increases power is interesting. Rather than increasing muscle strength/mass, plyo exercises improve musculotendinous stiffness – thereby improving the “energy storage” and energy return during resisted movements. For example, plyo box jumps will, over time, improve the efficiency with which the energy stored in the tendon/muscle during landing is released. In a sense, it improves the “spring action” of the muscles and tendons. If you think back to my previous posts about ground contact time, you can see that a more powerful push off during running is beneficial. So what’s the evidence?

There are several studies that show a link beteween plyometric training and improved running performance. The one I like best (because the scientific method was the most rigorous) was published in 2003 in the European Journal of Applied Physiology. In this study the authors found that a 4 month plyometric program improved running economy and 3km race time by 2.7%.

While 2.7% isn’t a trivial improvement, I do have some concerns about most runners adopting plyo training. Essentially, I think that this is a high risk tool. The rate of injuries doing plyo training is relatively high, and I think that the most extreme drills – box jumps, cone jumps, etc, are probably best done only by experienced athletes with coaching supervision. More traditional drills such as on-track hopping and bounding are probably reasonable if done carefully. However, I think that the large majority of the improvements in economy seen with these drills can probably be acheived more safety with strength training…

• RW Spurrs, ML Watsford, AJ Murphy. The effect of plyometric training on distance running performance. Eur J Appl Physiol (2003) 89: 1–7.

In the last post, I outlined some of the possible benefits on running economy of increasing cadence. Increases in cadence may improve economy by shortening stride length enough to prevent overstriding (and thus braking), decrease ground contact time (and thus improve energy return) and may decrease injury by lessening impact forces on landing. I wonder whether a lot of the alleged benefits of fore/midfoot running aren’t simply due to the effect that they have on stride length and cadence, rather than the actual part of the foot that is landed on per se.

In this post, I will try to review some of the evidence for strength training as a way to enhance running performance.

The first thing to be clear about is definitions. By strength training, I mean focused strength exercises primarily for the lower body. The objective isn’t to “get bigger” but to enhance muscle unit strength and, more importantly, neuromuscular coordination and muscle unit recruitment.

There is a lot of evidence that focused strength training can improve running performance in both short and long distance events. For example, a group of Norwegian researchers found that a focused plan of “half squats” with heavy weights improved running economy by 5% and time to exhaustion at maximal aerobic speed (eg the pace you would run at when at VO2max) by 21%. This occurred after 8 weeks of 3 sessions a week. The most relevant figure from this paper is shown below.

Similarly, French scientists found that a 14 week program of heavy lower limb weight training, which occurred concurrently with endurance training improved running economy n 5km trials.

What is interesting about both of these studies (and shown in many similar studies) is that this improvement in running times occurred without an improvement in aerobic fitness as measured by VO2max. We can therefore conclude that the improvements were due to better efficiency in running (i.e. running economy). This was presumably because weight training improved the effectiveness of recruitment of the involved muscles or allowed the recruitment of stabilizing muscles – thereby improving stride efficiency.

During endurance training some runners find that their stride length shortened as compared to when they are focusing on speed training. A group of Spanish researchers demonstrated that weight training prevented runners from developing a “marathon shuffle”.

The trick for most of us is to actually find the time to add this type of work into our training regimen. I think that there are a few general rules that apply: start with small doses of weight training, begin in the off season, and don’t become a weight lifter rather than a runner.

In the next post, I’ll outline a strengthening program that combines the benefits of strength and plyometric training for endurance runners.

• K Stkren, J Helgerud, E Stka, and J Hoff. Maximal Strength Training Improves Running Economy in Distance Runners. MSSE 2008

• G Millet, B Jaouen, F Borrani, and R Candau. Effects of concurrent endurance and strength training on running economy and VO2 kinetics. MSSE 2002.

• J Esteve-Lanao, M Rhea, S Fleck,  and A Lucia.  Running Specific Periodized Strength Training Attenuates Loss of Stride Length during intense Endurance Running.  JSCR 2008.

Do you ever watch other people running? It seems like some of them float along, barely touching the ground, while others seem to labour slowly forward, with excessive movement and heavy footfalls. Think a bit about how the graceful ones look – quick, light steps, no overstriding and no scuffing and scraping noises when their shoes contact the ground. They seem more efficient and it shouldn’t be a surprise that they are. An exercise physiologist might call this “economy”.

Some of these attributes can be developed in an athlete by focussing on one thing – running cadence. Cadence is simply the rate at which leg turnover occurs (i.e. how many steps are taken per minute). If your left foot contacts the ground 70 times per minute, your cadence is 70.

Jack Daniels made the observation that the best athletes in any distance over about 2000m run with a cadence of about 90. No matter the speed, cadence stayed pretty much the same, only stride length varied. Most beginning runners tend to run with cadences of 80/min or less.

Daniels suggests that quick cadence decreased injury by minimizing vertical oscillation (and therefore landing forces) and is more economical because it minimizes “ground contact time” – GCT. GCT is the time that a runner’s foot spends on the ground with each step.   As an athlete’s speed increases GCT naturally decreases, but this can still vary between runners. A shorter GCT implies that you are spending less time planted on the ground, but also the force generated by each step occurs over a briefer period of time, which minimizes force absorption and dissipation. Daniels felt that we should all aim to run with a cadence of approximately 90/min, as this was optimally efficient.

I recently came across a great post by Roberto Veneziani on his excellent blog, wherein he charted his cadence versus his Polar “Running Index”. The Polar Running Index is a proprietary measure that attempts to give you a global assessment of your running performance during any workout. Although the exact formula is not public knowledge, it isn’t that difficult to figure out. Basically, it calculates what your heart rate is as a percentage of your max HR (used as a surrogate for VO2max) and measures your running speed at that HR. By normalizing your speed to heart rate, it can compare runs at different speeds. Simply put, it can tell you if you are getting fitter/more economical over time, even if you are running at different speed and HRs. It thus gives a global measure of fitness and running economy.

Roberto compared his cadence to his running index over many runs and found that he got the best running index measures as his cadence approached 90. This would seem to support Daniels’ empiric observation that this is the cadence for optimal performance in longer distance events.

 Beyond GTC and decreased vertical oscillation I wonder whether there might be biochemical reasons why optimal running economy might happen around 90 strides/min. In a study performed in the early 1990s, eight cyclists were asked to pedal on two occasions at 85% of their VO2max for 30 min. The first time, they used a bike gear that required a cadence of 50 rpm, and on the second occasion, a gear that required a cadence of 100 rpm.

With the slower cadence (i.e. higher resistance) pedalling Type II muscle fibres (“fast twitch”) used up glycogen  50% faster than during high cadence (lower resistance) pedalling. Type I fibres (“slow twitch”) used fat and glycogen at about the same rate at either cadence.

So why might this affect economy? At slow cadences, as type II fibres run out of glycogen, they are less able to contract, forcing the recruitment of other muscle groups. This leads to: i) deterioration in form and ii) less efficient use of energy and oxygen. Both of these factors can contribute to less effective cycling.

I haven’t seen similar research in runners, but it isn’t difficult to imagine that a similar process might apply. Very slow gaits, with more vertical oscillation, greater ground contact time and so on require more use of type II fibres, and less efficient glycogen/oxygen use with concomitant deterioration of running form. This could lead to poorer economy. Just a theory, but it is biologically plausible. Something I will have to test in the lab someday, I think!

Take home message? Gradually try to increase your cadence to a number close to 90/min. Changes in speed should come more from variations in stride length than changes in cadence.

• J Kang, J Hoffman, M Wendell, H Walker, and M Hebert. Effect of contraction frequency on energy expenditure and substrate utilisation during upper and lower body exercise. Br J Sports Med. 2004 February; 38(1): 31–35.

• The Effect of Pedalling Frequency on Glycogen-Depletion Rates in Type I and Type II Quadriceps Muscles during Submaximal Cycling Exercise, European Journal of Applied Physiology, vol. 65, pp. 360-364, 1992.

Many people have asked me for my gear and food lists for the 2009 Marathon des Sables, as well as opinions on what I might change. I’ve attached both here as clickable thumbnail pics. This is exactly what I took, and if I were to do the race again (which I might!), I wouldn’t change anything. Still, this has to be seen within the context of goals, experience and history. My goals were modestly ambitious and my experience with ultra light gear was fairly extensive. I’ve camped cold a bit before, so the minimalist sleeping bag and clothing weren’t a big issue – others were very cold at night, so there is a fair bit of individual gear testing that you should try before simply adopting this list. Here’s the food list too. Actually, now that I think of it, I would have taken more variety of dmeals. Chicken and rice got pretty old after 8 meals…

One thing I learned in the lead up to the race was how much I hate those stupid front packs that a lot of adventure racers wear. I could never get it to sit right, and in the end, I left it at home completely. Mike, a fellow competitor posted his feelings about the front packs he used on his website, which I have reproduced here…

The last several posts have examined some of the science around footstrike patterns with respect to injury, economy and speed. I think that it is fair to say that proponents of mid/forefoot running have “ a whole lotta ‘splaining to do” before objective observers will believe that it is intrinsically better than the more typical foot strike pattern. There are some useful ideas within the Chi/Pose models – ideas like landing under the centre of gravity.  I don’t want to give people the impression that I’m a technique nihilist and that I don’t think that there is anything that can be done with respect to technique to improve an athlete’s speed and economy.

             Trail running in Italy’s Dolomite Mountains – La dolce vita!

Over the next series of posts I’ll look at the evidence for several areas that I think that a runner can improve technique. Namely, we’ll look at the evidence for:  i) foot contact time and cadence, ii) plyometric and strength training and iii) high speed running - ways to improve speed and economy without necessarily increasing fitness (yay, free speed!). 

As I’ve said before, none of these ideas are secrets, and you don’t need to buy expensive training courses to learn, utilize or benefit from these strategies. As always, these techniques need to be adopted slowly, preferably under the supervision of an experienced and credentialed coach who can evaluate you as an individual.

In previous posts we’ve looked at the contention that forefoot running might reduce injuries or be more economical. It doesn’t appear to do either of these things in a consistent manner (at least when examined from the point of view of the scientific literature). Of course, the reason that we care about injury and economy is that they both relate to training and competition speed. As always, what we want is to get faster – fewer injuries with better economy is the way to get there.

When I tell groups of runners that it is not clear that forefoot running helps with economy or injury, it is inevitable that someone will ask me about the running style of the current crop of world class runners from East Africa.  As most of you are aware, there is a widespread belief that (possibly due to running barefoot as children), runners from this part of the world run with a method that looks like Pose/Chi/forefoot running.  The logical contention is then that running this way will make us run like Kenyan superathletes (wouldn’t that be nice!).

Leaving aside the fact that the speed of the world’s best runners may have nothing at all to do with their foot strike (how about more important things like weight, training, limb length, etc?), is it in fact true that the fastest runners have a consistent foot strike style that can be emulated?

In 2007, Hiroshi Hasegawa and colleagues analysed the foot strike patterns of elite runners in a half marathon. Using slow-motion video analysis these researchers captured the foot strike pattern of the runners at the 15 km point.  On average 75% ran with a heel strike pattern, 24% with a midfoot strike and less than 2% with a forefoot strike.  All that we can really conclude from this is that some fast runners use a heel strike pattern and some a midfoot pattern. There were exceedingly few that used a forefoot strike (see image from the paper at left - “Figure 2″).

A similar paper looked at Naoko Takahashi (gold medal in the 2000 Olympic Marathon) as she ran on the treadmill. This group of researchers concluded that Takahashi ran with a midfoot strike. While this was on a treadmill and not on road, there is little reason to believe that she would change her gait simply because she was tested on a treadmill.

So what about Kenyans and Ethiopians? Well, here is a video of Haile Gebrselassie – a runner you may have heard of! What I find interesting is that he appears to be running with a heel strike pattern with one foot and a midfoot strike pattern with the other.

Now what is interesting is the following video of  the Little Emperor and Tergat racing in a 10K. Gebrselassie’s foot contact looks a bit different…. Is this due to different age, different training or different pace (I think most likely the latter).

Most people change their foot strike pattern as they move through a range of speeds – unconsciously. the body is remarkably well designed to minimize energy use, and I think that at different speeds, it “knows” to change landing mechanics. Try running a 100m as fast as you can, and then a half marathon  – your contact point will be different, virtually gauranteed.

So what to conclude from all of this data? It seems clear that the majority of the world’s fastest runners in long distance races do not run with a forefoot or even midfoot strike. However, it is also clear that there are some that do. It is my opinion that foot strike patterns are naturally determined by our own unique combination of anthopomorphics, biomechanics and physiology – our body finds the pattern that is most efficient for each of us. For some, this may be forefoot or midfoot, but for most it is not. Additionally, this strike pattern changes as we change our speed. I am extremely sceptical that there is a “best” foot strike (or even running style) that can be blindly prescribed to every runner. Instead, I think that our body’s governing centres adopt a pattern best suited to our individual needs based on energy output, speed and body type. This is not to say that some of us don’t run with injurious or pathological gaits that could benefit from coaching and adaptation. However, this needs to be done slowly, with careful analysis of the individual runner’s style and gait, not in a wholesale manner designed to sell books and videos.

• H Hasegawa, T Yamauchi, WJ Kraemer. FOOT STRIKE PATTERNS OF RUNNERS AT THE 15-KM POINT DURING AN ELITE-LEVEL HALF MARATHON.  Journal of Strength and Conditioning Research, 2007, 21(3), 888–893.

• YAMAUCHI, T., AND H. HASEGAWA. The motion analysis of a gold medal marathon runner Naoko Takahashi during the race at Sydney Olympic. Monthly Journal of Track and Field. 8:146–151. 2002.

In the last post, I addressed some of the purported injury prevention advantages of forefoot running and then looked at the available evidence. In this one, I’m going to try to review the data around running economy and technique. Once again, I’m going to focus on the ideas popularized by Chi, Pose and Evolution Running as they have “put themselves out there” by offering solutions for money. In future posts, I’ll offer some suggestions (for free) about how to improve economy.

The first question, of course, is “what is running economy”.  Essentially, when a physiologist approaches this issue, s/he wants to know the oxygen cost of movement. The less oxygen it costs to move a certain distance (or at a certain speed) the more economical a runner is. The corollary is that if you are more economical, you can run faster for a given heart rate or cardiac output (if you want a detailed explanation of these concepts check out this page).

Running economy is often proposed to be a primary determinant of competitive endurance running success and is defined as the oxygen cost per kilogram body mass per kilometer run. However, changes in running economy link to running technique  with 54% of the variation in running economy attributed to biomechanical variables.

Now economy isn’t just about technique – it also encompasses the efficiency of intracellular processes (i.e. how well your cells process oxygen) and neuromuscular adaptations (“springiness” of tendons, coordination of movements). It’s a global measure, and training in a new technique could only be expected to alter the “style” portion, not the intracellular and neuromuscular portions.

All that aside, some proponents of forefoot running suggest that it is a technique inherently designed to improve running economy, via increased use of the stretch-shortening cycle in the Achilles tendon, and better foot placement on landing (i.e. landing under the hips and not in front of them, which may cause braking). Once again, these are not necessarily ludicrous theories – but like so many theories, do they stand up to examination of the evidence?

The only study to look directly at the Pose method was performed in 2004 and looked at running economy in triathletes. 16 athletes had their running economy assessed at the beginning of the study period. Half of them continued with their normal running volume and technique. The other half were personally instructed by Dr Romanov over 12 weeks in the Pose method.  They maintained their running volume during this time. At the end of the study, all triathletes had their indices of running economy remeasured. The Pose athletes showed an increase in oxygen cost for running at a submaximal speed as compared to before training. This means that they got worse with respect to running economy – and thus less fast.

Now of course, it can be argued that their economy was worse as they had just learned the technique. This is possible, but still, they had 12 weeks with Dr Romanov himself – a lot more than you will get in a 2 day course or DVD.

It is certainly possible that there is a combination of circumstances (i.e. the right runner, the right surface and the right training) that might produce a situation where forefoot running is the most efficient running form. This might be true for the often cited Rift Valley runners who are lightweight, run from youth on somewhat forgiving surfaces and build up the musculotendinous strength to tolerate forefoot running stresses. It’s also possible that some more typical recreational runners might benefit from this style, either as a training supplement or as a primary running form. All that we can really say from published scientific data is that improvements in economy weren’t obvious in a group of well training runners that recieved significant coaching in the Pose style.

So will forefoot running make you more economical? The limited evidence doesn’t seem to support it for most people.

• GM Dallam, RL Wilber, K Jedalis et al. Effect of a globalalteration of running technique on kinematics and economy. Journal of Sports Sciences. 2005. 23: 757-764.

Let’s first look at running technique and injury risks. I don’t know a runner that hasn’t been injured by running, and for some of us, injuries prevent us ever reaching our potential.   

What is interesting is that the rate of injuries has gone up over time, despite greater attention to injury prevention, “improvements” in shoe design and so on. I think that  this is probably due to the change in the type of person who enjoys distance running over the last several decades. In the 70’s and before, the typical distance runner was “born to run” – i.e. they were naturally light and lean, and often had a background in shorter distance running prior to beginning distance training. The democratization of running over the last 30 years has allowed a far greater number and variety of people to run long. These new, perhaps more recreational, runners are often heavier, and often do not have years of shorter distance running behind them. Both of these factors may have led to an increase in injuries.

 What ever the reason, injury is common in distance running. I’m frequently slightly injured, and my first response has usually been the wrong one – to try to “gut it out” and train through it. I think that if those of us prone to injury could find a way to prevent injury in the first place, we would take it.

 Many advocates of forefoot running feel that the major source of runners’s injuries is heelstriking, and that moving to a midfoot or forefoot strike will decrease any runner’s risk of injury. I certainly have friends that have seen improvements in their injury rate with a change to forefoot strike a la Pose or Chi running.

 Unfortunately, I’ve also talked with many who have seen no improvement, or increased injuries with these changes. So what’s the evidence?

 Proponents of forefoot landing point out that landing on the heel generates massive forces that are transferred through the knee. Quite reasonably, they suggest that these forces are what lead to knee , hip and back injuries in runners. Forefoot landing, they believe, will decrease these injuries by putting the forces through the Achilles tendon as well as the calf. All in all, a not unreasonable theory.

 A study to look at this issue was performed by the sport physiology group at the University of Cape Town, in South Africa.  As many of you will be aware, this is where the great Tim Noakes works. In fact it was some of his research trainees that undertook the study.

 In this study (references below),  a group of proficient runners were taught the Pose method of running. Their education was extensive (over several weeks, by Dr Romanov himself) – so presumably they actually “got it” better than you could by reading a book or going to a 2-day conference. All of the runners had an extensive evaluation of their running kinetics and kinematics before and after their Pose education. This included measurements of stride rate, length, joint angles and force through joints and contact surfaces.

 The changes noted with training were that cadence was higher and stride length was shorter – as Pose would predict. Importantly, power absorption and eccentric work at the knee were lower after Pose training than in either heelstrike or midfoot running but there was a higher power absorption and eccentric work at the ankle in Pose compared with heelstrike or midfoot running.

 Now this is certainly interesting, as higher eccentric work through the knee during running is associated with higher rates of knee injuries in runners. It’s therefore not unreasonable to theorize that forefoot running might decrease knee injuries. Note I say “theorize”, because this has not been demonstrated. The Pose website (beautifully constructed, and so, so tempting) takes this one step too far and actually claims injury reduction.

Unfortunately, nothing is free in life! The price of decreased forces at the knee is increased eccentric work and power absorption through the ankle. This, I theorize, might lead to higher rates of Achilles tendon and calf injuries. So you’re trading the risks of knee injuries for ankle, Achilles and calf injuries.

 I recently read a post by one of the study participants (also one of the authors of the excellent Science in Sport blog), who described what happened to the runners after the 2 week training and testing period. He states that: “… what happened next was never going to be published in a scientific journal by the advocates for the technique, and would certainly not be reported on the website alongside the claim of reduced work on the knee! For what happened is that of the twenty runners who were trained, more than half broke down with calf muscle injury, Achilles tendon strains and other injuries of the feet!”

 Hardly a ringing endorsement for forefoot running as an injury cure-all.

 So does forefoot running automatically prevent running injuries? To my mind, the biomechanical evidence and research does not support this idea yet. However, I do think that it shifts the pattern of stresses in the foot, leg and hip. There may be a silver lining in this. For some runners, prone to injuries of the knee and hip, forefoot running may allow some relief (although there is a good chance you’ll develop a new set of injuries!). So if you’re chronically injured in the knees or hip, it might be worth a try. If you have ankle, calf or Achilles tendonitis, I wouldn’t try it. If you aren’t regularly injured, I can’t see a benefit either.

• Ferber, R., Hreljac, A., Kendall, K. D (2009). Suspected Mechanisms in the Cause of Overuse Running Injuries: A Clinical Review. Sports Health: A Multidisciplinary Approach 1: 242-246

• ARENDSE, R. E., T. D. NOAKES, L. B. AZEVEDO, N. ROMANOV, M. P. SCHWELLNUS, and G. FLETCHER. Reduced Eccentric Loading of the Knee with the Pose Running Method. Med. Sci. Sports Exerc., Vol. 36, No. 2, pp. 272-277, 2004.

The first issue we should probably look at is – why do we even care about running technique? Why is there so much angst over this issue, as opposed to, say, hand held vs backpack hydration systems? Why do we spend our time thinking about this, as opposed to trying to revive Bjorn Borg style head bands?

 The fact is,  many (or most!) of us harbour the secret belief that there is a technique, or style, or running that will instantly make us less injury prone, more efficient, and therefore FASTER. And faster is what we all want to be.

Unfortunately, anytime there are people desperately looking for a solution, someone will try to give them an answer. When there’s money involved, very quickly the hucksters appear and start marketing solutions that are “unique”, based on secret information, and , of course, can only be learned through a DVD, course, or book (which, by the way, aren’t free). Sadly, I think that there are several groups that have tried to cash  in on our need for a solution. I’ll leave this issue for a later post, but suffice it to say, there is no secret information!

So if we hope that technique changes will help decrease injury, improve efficiency and make us faster, it seems reasonable to try to examine the evidence for different techniques in light of these 3 aspects.

In the next several posts, I’ll look at the evidence comparing what I will broadly term “forefoot running” versus flatfoot or heelstrike running. Currently, Pose running and Chi running are popular exponents of forefoot running, so I think it is fair to examine some of the data around these methods too.

It doesn’t take long watching a race, or running with friends, to realise that there are a wide variety of running styles. Some runners seem to float along with virtually no ground contact, while others (such as yours truly) lumber forward, each step a precarious balance between falling and stalling. It’s also clear, if you read running magazines, look at internet running forums, or attend any gathering of runners that there are strongly held convictions about how “best” to run. The latest fashion has been to promote “forefoot running” as superior to “heel striking”. It is amazing to me that there are such emotional, powerfully held convictions about this issue amongst runners of all levels. I’ve been at many running events, camps and conferences where heated arguments ensue over this issue, with both sides providing little evidence other than personal experience and anecdote.  

So what is the evidence? Is there a best technique for all runners? Can we try to examine this issue without resorting to arguments that begin with “I was always injured until…”, “As humans evolved…” or “Look at how Kenyans/children/ancient Babylonians run…”.

Over the next several posts, I’ll try to sift through some of the opinions and evidence and hopefully come up with some ideas about rational technique improvements and finally some drills that may help with injury and efficiency concerns.

Let’s look at a hypothetical 80kg competitor:

Disclaimer - all of these numbers are extremely inaccurate and subject to a huge number of modifiers. If you are an 80kg competitor, please don’t use this as a plan. Get a real live physiologist to help you – individual results depend on individual experiences.

Weight – 80kg
Height – 5′ 10″
Age – 40
Gender – Male (results are only minimally different for women of same composition)
Body Fat – 20%
Calories of food taken to MdS – 20000

So this runner will have basal metabolic needs in the 6.5 days of the race of about 11700 cal (1800 x 6.5). Note, we often add a stress multiplier to the Harris-Benedict equation. I have omitted this for simplicity’s sake.

He then has to run 250 km. If this was on flat trail, with no pack that would cost about 20000kcal. Let’s assume the pack adds 15% – now the cost is 23000 kcal. How much harder is the MdS terrain than a flat trail? Don’t know, but assume that 3 hour marathoners take 4 hours to complete the marathon day, so maybe the MdS is 30-50% more difficult per km. So let’s guess 40%. Now the energy cost of running the MdS is 32200kcal.

So total energy expended in these 6.5 days is 32200 + 11700 = 43900kcal. I am virtually certain that this is a significant underestimate. One of the questions I am trying to answer in the study I am hoping to do with some of this forum’s members is to actually determine the true energy cost.

Okay, so our hypothetical runner will use 43300kcal in the MdS.

His food for the week totals 20000kcal. Assuming he neither steals nor loses any other food, this still leaves a deficit of 23000kcal. (Actually it is probably a bit worse than this, as, depending on the food that you take, a portion of the calories eaten will be burned during digestion, yeilding less than 20000kcal of total energy available. But let’s ignore that for this example…)

So where does the 23000kcal come from? Simply put, from the competitor’s stored energy. Ideally, this will all be from body fat, but, unfortunately, a portion will come from catabolism of muscle. How much exactly will depend on a large variety of factors. If we assume this is all from fat, the energy could be supplied by 6.7 lbs of fat.

Our competitor has 35.2 lbs of fat (20% of 80kg), so more than enough to support the energy deficit. He won’t starve to death on 20000kcal in the desert.

The real question with respect to performance, though, isn’t how much food does he need to survive, but how much, and of what type, does he need to maximize energy availability during exercise to maximize performance. Now that’s an interesting question…

In the previous posts, we have discussed some of the general principals of nutritional support during a multi-day race. It’s clear that adequate nutrition, combined with adequate recovery and good nutritional substrate selection can greatly boost an athlete’s performance. The question that necessarily follows the is – “how MUCH food do I need?”. This is a bit more tricky, and depends on several factors, not least of which is your size, as well as your intended running intensity.

Your basal metabolic needs are about 35 kcal/kg/day or so for an 80kg runner (178lbs) therefore your basal need per day is 2000kcal. If you are going to run 250km your energy needs, if running on flat road with no pack is about 1 kcal/kg/km. So for a 80 kg athlete 20000 kcal would be needed for the week. The total sum? 6 or 7 x 2000 for basal needs plus 20000 is 32000 to 34000kcal. For a 50 kg athlete the total would be around 22000 to 23640 kcal. I am sure that these estimates are very much on the low side, as terrain and conditions will be more difficult than typical. Actual needs could be as high as 55000kcal…

Lets assume that a runner takes 14000kcal as food. If s/he weighed 80kg at the beginning of the race, s/he will need to catabolize 22800kcal of energy from fat and muscle stores during the race. A pound of fat is about 3500kcal, so this 80 kg runner could expect to lose 6.5 to 7.6lbs of fat (if we assume 55000kcal total energy need this would be 14.6lbs!) Unfortunately, it is unlikely that all of this energy will come from fat, some will come from muscle catabolism, which may hinder performance. This all assumes that you have enough body fat to begin with.

 At the end of each day’s effort, you will probably want to hang out with other runners, relax or just sit and wish you had never signed up for such a  ridiculous race. You may not be thinking much about eating, particularly if you are hot or feeling nauseous. However, it is essential that you work on early restoration of your glycogen stores. A classic exercise science study showed that a typical diet (with about 45% of calories derived from carbohydrate) produced a steady depletion in muscle glycogen during three successive days of running training (16 km per day).

However, when runners were given additional dietary carbohydrate, they achieved near maximal repletion of muscle glycogen within 24 hours. We know that the timing of this carbohydrate reloading is key. The  highest muscle glycogen synthesis rates occur when large amounts of carbohydrate (1-1.85g per kg of body weight per hour) are consumed immediately after exercise and at 15- to 60-minute intervals thereafter, for up to five hours.

Cooking up carbs and protein in a 4-to-1 ratio

It seems possible that combining protein with carbohydrate in the two hours after exercise can nearly double insulin release, which results in more stored glycogen (insulin is a powerful hormone that is centrally involved in the management of glucose levels and in carbohydrate/glycogen storage). The optimal carbohydrate to protein ratio for this effect is 4:1 (four grams of carbohydrate for every one gram of protein). One study found that athletes who refueled with carbohydrate and protein had 100 percent greater muscle glycogen stores than those who only ate carbohydrate. Consider adding protein or amino acids to your post effort meal (0.4g of protein per kg of body weight).

 Summary: Eat 1-2 g/kg carbohydrate within 30-60 min of exercise. Repeat this every hour. Consider adding 0.4g/kg protein to this to increase glycogen re-synthesis and muscle recovery.

• Williams MB, et al. Effects of recovery beverages on glycogen restoration and endurance exercise performance. . Betts JA, et al. 2003 Feb;, J Strength Cond Res. , p. 17(1):.

• Ivy JL, Goforth HW Jr, Damon BM, McCauley TR, Parsons EC, Price TB. Early postexercise muscle glycogen recovery is enhanced with a carbohydrate-protein supplement. . 2002 , J Appl Physiol. , pp. Oct;93(4):1337-44. .

• Zawadzki KM, Yaspelkis BB 3rd, Ivy JL. Carbohydrate-protein complex increases the rate of muscle glycogen storage after exercise.1992 , J Appl Physiol. , pp. May;72(5):1854-9. .

• Levenhagen DK, Carr C, Carlson MG, Maron DJ, Borel MJ, Flakoll PJ. Post exercise protein intake enhances whole-body and leg protein accretion in human. 2002, Medicine and Science in Sports & Exercise. , pp. May; 34(5): 828-37.

• Miller SL, Tipton KD, Chinkes DL, Wolf SE, Wolfe RR. Independent and combined effects of amino acids and glucose after resistance exercise. .  2003 , Medicine & Science in Sports & Exercise, pp. March; 35(3):449-55.

Eating large amounts of two different carbohydrates during prolonged exercise allows greater conversion of carbohydrate to energy than ingesting one alone. Combining maltodextrin with fructose can elicit higher carbohydrate oxidation rates during exercise than maltodextrin alone because they use different intestinal carbohydrate transporters. This means that more carbohydrate can be absorbed from your intestinal tract more quickly, potentially decreasing fatigue and improving performance…Peak conversion of ingested carbohydrate to energy measured during the last 30 minutes of exercise was about 40% higher when athletes used a combination of fructose and maltodextrin (1.5g/min)  versus maltodextrin alone (1.06g/min). There are a vast number of powders and gels available. You may wish to experiment with ones that contain a mix of fructose and maltodextrin as fructose can cause discomfort and diarrhea in some athletes.

• Wallis, A., et al. Oxidation of Combined Ingestion of Maltodextrins and Fructose during Exercise.  2005, Med Sci Sports Exerc 2005, pp. vol 37, no 3, 426-432.

Carbohydrate is the best fuel for your body during intense exercise. Endurance athletes can only store about 400g of muscle carbohydrate (as glycogen) and around 100g of liver glycogen. This amounts to not much more than 2000kcals (500g x 4 kcal/g) in total – enough for about 25 km of fast pace running for a 75 kg athlete.

 Happily, well-trained endurance athletes can supply some of their energy needs from fat, even at moderately high intensity levels. Although fat and protein can both serve as fuel sources, carbohydrate is still essential for high intensity performance. There are several reasons why carbohydrate is an important fuel, but one of the most important is that only carbohydrate can supply energy rapidly enough to generate ATP (the energy releasing molecule used to drive muscular contraction) during vigorous exercise. Furthermore, even when exercise intensity is lower, and more of the energy can be derived from fat, a continual breakdown of carbohydrate is required to allow the efficient oxidation of fat for energy.

Me, wishing I had something other than Chicken & Rice for a week

So how much carbohydrate should be eaten during running? The answer is essentially “as much as possible”. For example, assuming an athlete runs 10km/hr (very fast over this terrain – less than 5% of competitors can achieve this!) during the MdS, and given the difficulty of the terrain (30-50% more energy needed per km run than normal trail or road) a 75 kg athlete will burn approximately 1000 calories per hour. Most athletes of this size can only ingest around 250-300 cal/hr. So no matter how much you eat, you will still be “running a deficit”. Your goal should be to eat as much as feasible without causing nausea. This is typically around 250 calories per hour.

Many people feel that a bit of protein makes them feel better during long efforts. If this is true for you, then use a food plan that has some protein in it. I would not recommend foods with significant fat in them if your effort is going to be intense. Ingested fat slows down the emptying of food from your stomach (potentially leading to nausea), and is not readily available as an energy source during exertion. Some people deliberately include fat in their intra-race food for very long events – specifically because it improves taste/palatability and the sense of “fullness”. These seem like good reasons to me – but don’t do it simply to “get more calories”, it doesn’t work that way…

 Summary: 250 kcal an hour (if you can) from the first to the last step of the race. Focus on carbohydrate!

Overnight, your liver glycogen stores can deplete by as much as 50g (of 100g total). Your muscle glycogen stores (400g) are unaffected. One of the main purposes of the prerace meal is to top up your liver glycogen stores. As it takes a while to full digest your breakfast and form glycogen, this meal should happen about 2-3 hours pre race start. Again a relatively high carbohydrate percentage is called for (80% or more).

There are some additional theoretical reasons why eating your pre-race meal within 2-3 hours may impair performance, particularly if your meal is composed mostly of simple rather than complex carbohydrates. It is possible that after the meal you will secrete a lot of insulin. This may lead to the inhibition of lipid mobilization (fat burning) during aerobic exercise, which means reduced fats-to-fuels conversion, and thus potentially less available energy. Additionally, high insulin levels  may enhance muscle glycogen depletion during exertion.  

 If you finish your pre-race meal about three hours prior to start time, your insulin and blood glucose levels will have to normalize, thereby avoiding these problems.  After three hours, hormonal balance is restored, and you won’t be at risk for increased glycogen depletion. Eating within three hours of a race promotes faster release/depletion of both liver and muscle glycogen and inhibits fat utilization. The combination of accelerated glycogen depletion and disruption of your primary long-distance fuel availability may impair your performance.

Summary: Eat a meal rich in complex carbohydrates 3-4 hours prior to start time

• Costill DL, Hargreaves M. Carbohydrate nutrition and fatigue.  1992 , Sports Med., pp. Feb;13(2):86-92.

• Wee SL, Williams C, Tsintzas K, Boobis L.Ingestion of a high-glycemic index meal increases muscle glycogen storage at rest but augments its utilization during subsequent exercise.   2005 , J Appl Physiol. , pp. Aug;99(2):707-14.

• Coyle EF, Coggan AR. Effectiveness of carbohydrate feeding in delaying fatigue during prolonged exercise.  1984, Sports Med. , pp. Nov-Dec;1(6):446-58.

• Dennis SC, Noakes TD, Hawley JA.Nutritional strategies to minimize fatigue during prolonged exercise: fluid, electrolyte and energy replacement.   1997 Jun, J Sports Sci. , pp. 15(3):305-13.

Over the next few posts, I will outline some of the information I used to prepare nutritionally for the Marathon des Sables 2009. The strategies are applicable in large degree to other races and types of events. As always, try nothing new on race day(s).

There is a great deal written about carbohydrate loading strategies pre-race. I think that the evidence supporting these is reasonable, but the reality of complex loading strategies is complicated by athlete motivation and the demands of travel and timing specifically related to the MdS. Traditional carbohydrate loading strategies usually involve one or more runs associated with carbohydrate restriction several days (i.e. 2-4 days) prior to the big event. The purpose of these is to thoroughly deplete liver and muscle glycogen stores. This depletion stimulates the activity of glycogen synthetase – the enzyme largely responsible for causing glycogen production and storage – beyond it’s normal levels activity. The athlete then eats large doses of carbohydrate, in an effort to saturate the body’s glycogen storage. It is theoretically possible to store enough glycogen this way to last a full marathon distance.

 I think that this specific type of protocol is not needed for the MdS. There are three reasons I would not recommend aggressive depletion-loading techniques

 Firstly, here are several risks. Specifically, running several long runs prior to the start day means running whilst tired from travel, which increases the risk of injury and illness. Additionally, this will probably occur while you are beginning to acclimatize to both the heat and the time difference. I would worry that this places too much physiologic strain on an athlete. It is my impression that fewer and fewer top athletes and coaches are using these strategies anymore because of the psychological and physical effects.

Jay Batchen - a great athlete and a great guy

 Secondly, the benefits of aggressive loading strategies diminish when the athlete is able to maintain blood glucose levels during running by eating. It is far more important to maintain adequate carbohydrate intake whilst running than to focus on difficult pre MdS loading strategies. Given the multiday nature of the MdS the small positive benefit in terms of liver and muscle glycogen density on day 1 is minimal.

 Thirdly, you will naturally undergo carbohydrate loading and glycogen storage during the week prior to the MdS as you taper your mileage. It is not necessary to eat massive amounts of carbs in the days prior to the race start. If you eat your normal amount of calories (possibly focused slightly more on carbs than usual) whilst dropping your training mileage, you will naturally store glycogen and fat.

 Besides carbohydrates, it is useful to think about “topping up” your electrolyte and water stores too. Travel to the competition, the dry environment and stress will all alter your water and sodium balance. Careful attention to hydration and a modest increase in sodium intake for 3 days prior to the race start will be of benefit.

 All of these strategies will cause you to be 0.5-2 kg heavier at the start line than your usual race weight. That’s not a bad thing – think of the weight as fuel.

It was hot, sandy and a long, long way.

I had the great pleasure of competing the “MdS” this year, and thoroughly enjoyed it. I ended up doing reasonably well (51st) and I credit this to 4 factors – good nutrition, good race tactics, good gear and good physical preparation. I beat runners that were significantly faster than me due to these factors and I’m thankful that I had some excellent coaching and advice along the way (more on that in future posts). There are dozens of race reports available on the web (I particularly recommend Rich - a UK ultrarunner) so I don’t think that I will rehash well covered ground. When I was preparing for the race myself, what I really wanted was specifics about the logistics – food, gear, training. So I thought it would be interesting to cover those in some over detail over the next few posts. I have a great interest in nutrition during endurance events, so I thought that I would start with a review of the evidence for different aspects of multiday race nutrition. After that, perhaps a bit about gear, tactics and training…

Welcome to the Endurance Science Blog! It’s been a long wait getting the new site and training software ready, so setting up the blog site has taken a lower priority. Thanks to everyone who sent ideas for articles – I’ll try to cover the topics over time…

 Endurance Science is an assessment and coaching group that focuses on endurance events. We are interested in the physiology of endurance, and developing outstanding athletes through the careful application of exercise physiology. Our area of greatest focus is distance running in all of it’s various forms – road races (10ks and longer), adventure races, ultramamathons and expedition running. If you want to explore what we have to offer, check out the links at the top of the page, or click on our logo.

This blog is an extension of my (William) interest in the art and science of endurance training and racing. I created this site so that clients, researchers and fellow athletes could talk about their experiences and learn from each other. I hope that over time we’ll see a wide variety of events (running, ski touring, cycling and multisport disciplines) discussed here, and that we can develop a real understanding of the science behind the sports that we love. So feel free to contribute!

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