I was pleasantly shocked when, a couple of years ago, a writer for the New York Times called to interview me about my new book, Brain Training for Runners. Although the resulting 1,200-word article misrepresented the thesis of my book and included uninformed criticisms from parties I had no opportunity to rebut, there is no bad publicity, as they say, and the piece undoubtedly gave a boost to my book’s early sales. And the mere fact that my name made it into the pages of the Gray Lady filled me with a fleeting feeling of pride, as a symbol of career success.

I doubted that my name would ever find its way into those hallowed pages again, but lo and behold it has - today. On page E8, in the Physical Culture department, there appears an article entitled “If You Weren’t Born With An Odometer” by Sarah Bowen Shea. It is a gear test that compares online training logs for runners against old-school paper logs, including mine, The Runner’s Diary. As the formula requires, the small section on my book includes a balance of positive and negative words.

No doubt the negative words are valid. But I don’t care. I’m in the New York Times!

Never in my life have I modified my diet to promote weight loss. Until now. My wife thinks I’m crazy to be doing so even now, because I’m already quite skinny: six-foot-one and 158 pounds. But when I look in the mirror I see little love handles that are not there when I am at my peak fitness level. I am certain that I will not perform optimally at Ironman Arizona if that extra flab is still there come November. When I was younger, any extra flab that I carried disappeared automatically as I increased my training load without my having to make any special efforts. But I’m 38 years old now, and my aging body seems to be less resistant to giving up any superfluous insulation it acquires. In the past, the amount of training I’m doing now was sufficient to make those little love handles go away. But no longer. So I’m putting myself on my very first diet.

Drastic measures are unnecessary. There are some simple things I can do to trim enough calories from my daily intake to get the job done. Most obviously, I drink too much beer. I go through 12 bottles a week, sometimes more. So I have decided to restrict myself to one bottle a day, except on special occasions, like Wednesdays (just kidding).

Normally I eat big lunches. My typical lunch is a 6-oz carton of yogurt, a turkey sandwich, carrot sticks dipped in ranch dressing, a tall glass of Odwalla Superfood, a piece of fruit and a small piece of dark chocolate. I have decided to replace this menu with home-blended fruit smoothies complemented with a slice of toasted whole-grain bread with all-natural peanut butter.

To keep myself from going insane with hunger, I will drink a carton of Forze GPS drink at 10 o’clock each morning and eat a Forze bar at 3 o’clock each afternoon. The drink has just 45 calories and the bar only 150, so even with the addition of these snacks to my diet I will consume fewer calories between breakfast and dinner than I have been, thanks to the substantial reduction in the size of my lunch.

I started this new diet on Monday, and so far, so good. I was fearful that even with the Forze products I would battle hunger in the afternoon, but I have not. Two days is not long enough to see results in the mirror, but I am confident they will come. I really drank a lot of beer.

Galen Rupp used a familiar strategy to win the USA Track and Field Championships 10,000 meters. He bided his time a few places from the front until the relentless pace set by Dathan Ritzenhein caused everyone else to drop away. Then, with 500 meters to go, Rupp casually accelerated, took the lead from Ritz, and powered away to victory.

When I discussed the race with a couple of colleagues who watched it with me, both suggested that they did not like the way Rupp had won, or his general sit-and-kick modus operandi. I’ve heard this sort of criticism before and it utterly mystifies me. Those who criticize sit-and-kick racing say that it is dishonorable; that it lacks integrity. When asked why, they reply that it is unfair for a racer to allow others to “do all the work” of leading and then “steal” the race at the end.

The notion that it “takes more work” to lead a track distance race than to follow the lead is pure poppycock, except in windy conditions. The speeds involved in distance running are too low for any drafting effect to come into play, as in cycling. Nor is it psychologically more demanding to lead than to follow. There are really two types of racers: those who feel better in the lead and those who feel better being chased. Naturally, it is those who prefer to lead who usually do, and for these individuals it is less psychologically demanding to lead than to follow.

Now, it so happens that it was windy for the men’s 10,000m at Hayward field last Thursday night and therefore the leader did pay a cost for leading. Did every man in the race then have a responsibility to take a turn leading? There were nearly 30 men in the field. Coordinating a paceline-like rotation among all of them would have been impossible. Nor does there exist any code of ethics in distance running that obligates the top contenders in such a race to take a turn leading. There are those who feel that such a code should exist, and who hold other runners accountable to the ethic of lead sharing as if it did.

But this attitude does not bespeak moral superiority. To the contrary, it is self-serving. You will find that the only runners who feel strongly that everyone should take a turn leading are those whose best chance to win is with a fast-paced race that defuses the kicks of the stronger kickers. It is the strongest kickers who practice the sit-and-kick style of racing, of course. So in insisting that everyone should help to push the pace, kick-lacking runners are doing nothing more than insisting that the strong kickers sabotage their own race and help them (the weaker kickers) win.

There’s a little more to it than that, though. When a sit-and-kick runner sits on the heals of the leader through 90 percent of a race and then overtakes him at the very end, it sort of looks and feels like stealing a win. But this is a purely emotional and non-rational response. It isn’t really stealing. It’s just frustrating to lose that way, so those who do lose that way develop an animus towards those who win that way.

Now, as a fan of running I am glad that not everyone is a sit-and-kicker. There is nothing more boring to watch than a race in which nobody wants to take the lead, like the dreadful Beijing women’s 5000m final. But imagine a race in which everyone wanted to lead! It’s impossible, of course, because everyone would sprint from the gun and blow up after two laps. And that’s just it: A race can have only one leader at a time. It is necessary that there be more followers than leaders.

Runners who insist on leading are typically very proud of their frontrunner mentality (Prefontaine, Famiglietti). But sometimes it’s just plain stupid. Prefontaine lost a few races he could have won because of his refusal to follow, and just last Friday in Eugene Anthony Famiglietti destroyed himself in the men’s 5000m through overzealous frontrunning.

I can appreciate both styles of racing. I love runners like Famiglietti who make every race honest by going out hard, and it is thrilling to watch a runner win this way, as Jenny Barringer did in the women’s 3000m steeplechase final at Hayward Field. But sit-and-kickers can be just as exciting to watch, as you sit on the edge of your seat with anticipation throughout the race, waiting to see if their kick will be there when they need it, and then mouth the word “wow” is it is unleashed and the rest of the field is suddenly left behind as though running in quicksand.

The greatest runner of all time, Kenenisa Bekele, is a sit-and-kicker. Watching Bekele run a 53-second closing lap in a 10,000m race is one of the most exciting spectacles in the sport. But that doesn’t mean I didn’t enjoy watching Bekele get his comeuppance in the 2004 Olympic 5000m final, when Bekele allowed mile world record holder Hicham el Guerrouj to hang around too long and got outkicked by perhaps the only man in the world with a faster kick at the end. That must have felt good.

My training possibilities are severely constrained here in Eugene. I still can’t run because of my heel. I’m now pretty sure I have a bone spur or stress fracture. I found a local YMCA with a pool and a few ancient exercise bikes, but I can’t spend a lot of time there, because I have a lot of work to do. Thank goodness, then, for the miracle of intensity. It is the traveling triathlete’s best friend. I spent just 30 minutes on the bike this morning, but got a terrific, truly fitness-preserving workout because I time-trialed the last 20 minutes. I rode at about 98 percent for the first 19 and then sprinted the last 60 seconds.

At the time I stopped pedaling I was breathing as hard as I ever breathe. And, interestingly, I kept sucking wind that hard for a good 30 seconds as I sat motionless on the bike. Sports scientists measure athletes’ anaerobic capacity by measuring their maximum EPOC (excess post-exercise oxygen consumption). The greater your anaerobic capacity is, the farther you can drive yourself into oxygen debt during hard exercise; the more work you can do beyond the amount of work that is allowed by your aerobic capacity, or maximum rate of oxygen consumption. Maximum EPOC quantifies this capacity to drive yourself into oxygen debt.

I cannot recall ever consuming so much oxygen in the first minute after completing a workout as I did this morning, which suggests to me that my anaerobic capacity might be greater than ever. I’m not too surprised by this finding, given how much high-intensity work I’ve been doing on the bike. A couple of supplements I’m taking - creatine and ARX - may also be helping. One study on ARX found that it improved performance in a fixed-work cycling time trial that tool about 5 minutes to complete (an approximately 75 percent aerobic, 25 percent anaerobic effort) by 18 percent. That’s big.

It started at the airport, where I saw Shayne Culpepper. At least I think it was Shayne Culpepper.It reached its apex when I stepped out of the rental car at the hotel where I was to interview Katie McGregor and Jorge Torres and literally almost ran into Alan Webb, who was getting into the passenger side of the cae next to mine. It got really crazy when my colleague Sean McKeon and I went to the stadium to pick up our media credentials. On her way out as we went in was Jordan Hasay. We rode the elevator with Lopez Lomong.On our way to the media credentials queue we ran into Dathan Ritzenhein waiting in the athlete support queue with his wife, Kalin.My last work obligation before breaking away to work out was attending an intimate media event with Tyson Gay.Steve and Sarah Slattery, Matt Downing,Rob Meyers…I almost can’t believe how many fast runners in street clothes I saw today. I think I’m the slowest man in Eugene this week.

Although I have been in the endurance sports media business since 1995, I had never set foot in Boulder, Colorado, until 2006. I went there then to watch the USA Cross-Country Championships and to meet Brad Hudson, with whom I was then writing Run Faster. I had also never watched a national championship running event in person until I made that trip.

It’s now 2009 and I still have never been to that other Mecca of American endurance sports (besides San Diego, where I live!), Eugene, Oregon - or Tracktown USA as it likes to be known. That will change tomorrow, when I fly there to cover the USA Outdoor Track and Field Championships for Competitor Running. I am so excited I can hardly contain myself. I am excited first of all to watch the races. Check out this preview I wrote for the website about the athletes, matchups and races I’m most geeked up about.

The other thing I am looking forward to is all of the video interviews we have lined up. Committed interviewees include Ryan Hall, the aforementioned Brad Hudson, Lolo Jones, Katie McGregor, Dathan Ritzenhein Alberto Salazar, and Jorge Torres. These will not be event-specific interviews (e.g. “How do you feel about your race?”). Instead, we will talk to these athletes and coaches about topics that matter to you as runners. We’re going after the news you can use. For a taste of what I’m talking about, check out my interview with Steve Scott, former American record holder in the mile, which will be posted on Competitor Running (running.competitor.com) on Wednesday.

The downside of all the traveling I am now doing on behalf of Competitor Running is that it messes with my training for Ironman Arizona. Speaking of which, if you know the Eugene area, please give me your recommendation for a good place to swim during the five days I’m in Tracktown USA.

A few years ago I was working at the Accelerade booth at a big race expo - I forget which race it was - when the activities at a nearby booth captured my curiosity. The product being peddled there was a novel but simple resistance training device that consisted in a pair of long straps with handles. The non-handle ends of the straps were attached to a horizontal bar at head height, allowing users to perform all manner of resistance bodyweight exercises from modified chin-ups with the heels on the ground and the body at a slant to elevated push-ups with the feet hooked into the handles.

Eventually I got a chance to stop by the booth, where I met a former Navy SEAL who had helped develop the product. He took me through a quick workout, which was humbling. The balance component that is inherent to working out with this device, called TRX, makes familiar movements more challenging.

That’s the last I saw of or heard about the TRX until a few weeks ago, when I was contacted by Jon Binder, an employee at Fitness Anywhere, the company that manufactures the TRX, who said he was interested in exploring the possibility of partnering with me to take the device into the endurance sports market. Having been excited about the possibilities for suspended body weight training (the generic term for training with devices like the TRX, which now has a couple of competitors) as a means to develop muscle balance and power for running and triathlon when I first tried the product, I readily told Jon that I was open to this possibility.

Step one in the process occurred last night, when I was reintroduced to suspension training by Neil Mallinson, a TRX master trainer who is based in San Diego County. Over the course of that hour I was reminded not only of how effective suspension training is for functional strength and power development, but also how fun it is. It’s like playing with a toy. Indeed, the workout took place under brilliant sunshine on a grass field at Swami’s Beach in Encinitas. The device was attached to a tree branch.

I got to take one of these toys home with me. Over the next few weeks I will use it to translate the strength training programs I have developed in the past for runners and triathletes into suspension training, and see where this leads me. Of course, one of the great benefits of the TRX is its extreme portability, and it so happens that I will be on the road from Wednesday through Monday at the USATF Outdoor Track and Field Championships in Eugene, giving me the perfect chance to see what it’s like to use the TRX in a hotel room, as a great many people do.

I’ll let you know how that goes.

The following question is often asked: Is it better to lose weight slowly or quickly? Most experts say it is best to lose weight slowly because slower weight loss is more sustainable and may be healthier because it carries less risk of nutrient deficiencies and usually results in less muscle loss. On the other hand, data from the National Weight Control Registry suggests that dieters who lose weight rapidly are just as likely as slow weight losers to sustain their weight loses over the long term.

But how about athletes? It seems reasonable to speculate that rapid weight loss is less advisable for athletes than for non-athletes because of its potential for detrimental effects on performance. And a new study from the Norwegian School Of Sport Science suggests that slow weight loss is indeed the better way to go, at least for strength and power performance. 

Thirty “elite” athletes participated in the study. They were divided into two groups. Members of one group adjusted their diet to accomodate a target weight loss rate of 0.7 percent per week. Members of the other group aimed to lose weight at twice that rate. All of the subjects continued on their respective diets until they reached their goal weight or for 12 weeks - whichever came first. In addition, all of the subjects lifted weights four times per week (in addition to doing their normal training) to minimize muscle mass losses.

Members of both groups lost equal amounts of weight, which I think suggests that most of the subjects were able to reach their goal weight. The abstract does not say whether the fast weight loss group got actually there faster - that would be very interesting to know. But overall, members of the slow group got better results. While body weight changes were similar, members of the slow weight loss group lost significantly more fat and gained nearly twice as much muscle.

The athletes were subjected to vertical jump, maximum squat and maximum bench press tests before and again after dieting. Members of both groups improved their performance in all three tests, but the slow weight losers improved more (8.0 percent to 4.3 percent in the vertical jump, 13.1 percent to 9.7 percent in the squat and 15.1 percent to 7.8 percent in the bench press).

One must be careful not to draw too general a conclusion from this study (for example, it’s possible that rapid weight loss works better for severely overweight non-elite athletes), but it does suggest that slow weight loss is better than fast weight loss for high-level athletes engaged in normal training.

Twice in my life I have swum at the San Dieguito Boys and Girls Club pool in Solana Beach, California. The first time was six years ago, when Roch Frey led me through the swim technique lesson that first transformed me - almost instantaneously - from a mediocre triathlon swimmer into a pretty good triathlon swimmer. The second time was yesterday, when Roch Frey, looking, like me, a little grayer and more lined in the face, led me through a swim technique lesson that I earnestly hoped would undo the reversion from pretty good to mediocre that my swim performance that had undergone since six years ago.

Since getting back into the pool in April I had tried and tried on my own to remember the tips Roch had given me and to make my body do what it had learned to do so well in the days following my first lesson with him. I experienced a few “A-ha!” moments that precipitated incremental improvements as measured by the stopwatch and, no less importantly, by the “rightness” of the feeling of swimming, but the breakthrough I really needed to restore past glory was not forthcoming. So about a month ago I contacted Roch and asked for help. Roch is a busy guy so he did the best he could in penciling me into his calendar four weeks later–yesterday.

It was a long, frustrating four weeks. I wanted to make use of that time, not merely kill time in the pool thrice weekly while I waited for Roch to wave his magic wand and make everything better. So I continued to fiddle with my technique in little ways, hoping for something to click. My measuring sticks of stopwatch and feeling right in the water told me that I was going absolutely nowhere for another two weeks, but in the last two weeks before my appointment with Roch my 100-yard splits began to creep downward and I felt a sort of neuromuscular coalescence inside me, which seemed to indicate that I was on the verge of rediscovering that elusive feeling of rightness, yet still it eluded me.

I was in an anxious state when I returned Roch’s firm handshake on the deck of the Boys and Girls Club pool under gray skies yesterday morning. While reason told me that Roch would have no trouble spotting and showing me what I was doing wrong, and that I would have little trouble making the changes he recommended, emotion told me maybe not. Emotion made me childishly wish to skip past the fearful grasping of reaching for that technique breakthrough that must happen now if it was going to happen at all (such pressure!) and simply arrive at the post-breakthrough state - to skip past the painful and uncertain coccooning and find myself a butterfly.

“OK, why don’t you start by jumping in and warming up with an easy hundred, and I’ll just watch you,” Roch said. Tingling with nervousness I plunged into the cool water and began stroking. At first I was conscious only of an intense desire to put on a good show for Roch - to not embarrass myself by swimming ugly or laughably. But on the second length this self-consciousness faded and I became increasingly aware of a distantly remembered rightness in the feeling of my swimming. By the time I reached the fourth and final length of my warm-up I was having fun. I felt sleeker, more relaxed and stronger in the water than I had in more than five years.

“Well, you look like a swimmer,” Roch said as I grabbed the wall and found his face through my goggles, probably wearing the expression of a child showing his father an original poem whose quality he has no clue about. “Honestly, I don’t see anything major.”

Shock and disappointment flooded my head. There has to be something major! I thought. I’ve been swimming like crap. If I don’t make a major change, there’s no way I’m going to be able to swim as fast as I want to swim in Ironman Arizona.

Only later did I fully awaken to the realization that my big technique breakthrough had actually occurred within than warm-up, before Roch even had a chance to point out any flaws and suggest any changes. I guess I was so close to the breakthough at the time of our rendesvous that all I needed to pass the tipping point was a little positive self-consciousness - a little help from the audience effect.

It’s an amazing thing, this audience effect - how our performance capacities increase under the pressure of instincts that make us fear social embarrassment more than death, instincts that can be powerfully awakened by the presence of a single watcher. When I lead seminars on brain training I fondly describe a study by Arizona State University researchers in which volunteers were asked to lift as much weight as they could either in a group without competitive comparisons, and again in an actual competition, and once more in front of an audience of passive onlookers. The subjects were able to lift significantly more weight when performing alone before seated watchers than they were in competition, and lifted least in the non-competitive group environment.

That’s the audience effect for you. Long live the audience effect!

Every endurance athlete knows that VO2max is an athlete’s capacity to supply oxygen to the working muscles during exercise, and that endurance performance is strictly limited by this capacity. But what every endurance athlete knows is wrong. The truth is that VO2max is as much an effect of speed as it is a cause, and that VO2max is far from being the single most important physiological underpinning of endurance performance. In fact, VO2max is not a physiological capacity at all. It is really just an approximate way of measuring work output, or speed in the case of swimming, cycling and running. Therefore, to say that a triathlete is fast because he has a high VO2max is tantamount to saying that he is fast because he is fast.

Measuring VO2max has no practical value whatsoever. Sure, it’s a pretty good predictor of endurance performance capacity, but actual endurance performance (for example, a time trial) is a much better predictor, and much simpler to do. And while VO2max testing is often used as a tool to establish training intensity targets, this, too can be done just as effectively through simpler means.

Why, then, is VO2max made so much of by sports scientists, coaches, and athletes? Ross Tucker, PhD, a South African exercise physiologist and coauthor of The Runner’s Body (Rodale, 2009), points to two reasons.  “The attraction of finding a single value that determines your performance ability is too great to resist,” he says, “so the notion that VO2max is the physiological stand-in for performance potential has become something of a dogma among runners and within exercise physiology, despite the abundant evidence that performance is far more complex than a single number.”

“Another reason for the exaggerated importance of VO2max to performance is that it is so easy to measure and quantify,” Tucker continues.  “Some of the other factors that are recognized for running success, such as muscle-tendon elasticity, the ability to use fat as fuel and the capacity to generate ATP at rapid rates are a lot more difficult to measure, and often impossible to quantify or compare from one runner to the next.”

The problem is not only that the importance of VO2max is inflated, however. It is also that the meaning of VO2max is misinterpreted. Typically VO2max is understood to represent the capacity of the body’s cardiorespiratory system to supply oxygen to the working muscles. But as we will see presently, VO2max is equally representative of the capacity of the muscles to demand oxygen from the cardiorespiratory system. The reason behind this misinterpretation may also have to do with what scientists can and cannot observe. In athletes with high VO2max values, scientists always see a bigger heart that pumps more blood per contraction, greater blood volume, more haemoglobin in the blood, greater capillary density and so forth. Scientists also see growth of the heart muscle and increasing blood volume, hemoglobin and increasing capillary density in athletes as they train for endurance and as their VO2max increases. But while these observations provide compelling evidence that oxygen supply is a major component of the VO2max equation, they do not explain the whole enchilada.

Holes in the Theory

VO2max is measured through an incremental exercise test on a treadmill or stationary bike. The subject breathes through a mask attached to a machine that measures the rate at which are is inhaled and exhaled.  After warming up, the subject is required to exercise at intensities that increase by a fixed amount every 60 seconds.  For example, the typical stationary bike test begins with the machine set at a resistance level that yields 50 watts of power when the rider maintains a required cadence that remains fixed throughout the test.  The resistance then increases every 60 seconds such that the power output increases by 25 watts if the rider holds the proper cadence. The test terminates when the subject is no longer able to hold that cadence.

In approximately 30 percent of these tests, the subject’s rate of oxygen consumption reaches its highest level a step or two before he or she cries uncle. In the other 70 percent of VO2max tests, the rate of oxygen consumption increases all the way through the last step.  In these cases it’s impossible to say that the subject’s work output was limited by his or her capacity to supply oxygen to the working muscles. After all, a graph of the rate of oxygen consumption in the test would show an upward slope all the way through, suggesting an untapped capacity to use even more oxygen if only fatigue had not been caused by—something else.

Further evidence against the idea that the capacity of the cardiorespiratory system to supply oxygen to the working muscles limits endurance performance comes from studies in which individuals exercise at maximum capacity in hyperoxic (i.e. extra-oxygen) and hypoxic (i.e. reduced oxygen) conditions. Untrained and trained subjects alike exhibit increased performance in hyperoxic conditions and reduced performance in hypoxic conditions.  First of all, it’s unclear why extra ambient oxygen would increase performance if the oxygen transport chain were the athlete’s true limiter; if the athlete’s oxygen consumption capacity can be truly maxed out in normal air, then a hyperoxis environment should make no difference.  Also, if the oxygen transport chain were the athlete’s true limiter, then in hypoxic conditions we would expect to see reduced performance coupled with a normal level of motor output from the brain to the working muscles. This would indicate that the body was trying to work to full capacity but simply couldn’t because of inadequate oxygen availability.  But instead we see reduced motor output from the brain in these conditions, suggesting that the brain is for some reason reacting to subnormal oxygen availability by refusing to drive the muscles as hard as normal.

In the 1990s, Tim Noakes, MD, of the University of Cape Town, South Africa, proposed that oxygen consumption during exercise was not limited by the capacities of the various links in the oxygen transport chain but was instead governed by the brain, which served to cap exercise intensity by limiting muscle fiber activation (oxygen use is a direct function of the amount of muscle tissue activated) in order to prevent the consequences of exercising beyond the body’s true capacity to supply oxygen to the muscles, which could include heart attack. Recent studies have proven that Noakes’ speculation was right on the money.

One such study involving cyclists was published in the Journal of Physiology in 2006. In it, eight trained male cyclists performed 5 km stationary time trials on four occasions. The concentration of oxygen in the air they breathed varied from below that of normal air to above that of normal air in the four trials. Central neural drive (i.e. motor output from the brain to the muscles) was measured by EMG sensors placed on the quadriceps muscles. Changes in the amount of electrical activity recorded by these sensors among the four trials would indicate changes in how hard the brain was driving the muscles. Power output was also measured throughout each trial. And immediately before and after each trial, the quadriceps muscles were electrically stimulated to provide evidence of local muscle fatigue. A decline in the muscles’ responsiveness to this stimulation would indicate that fatigue had occurred within the muscle fibers themselves.

Power output was 30 percent greater and performance 12 percent greater in the hyperoxic time trial than in the hypoxic trial. Central neural drive was 43 percent greater.  But the level of local muscle fatigue recorded after each trial was the same.  These results indicate that the lower level of performance in the hypoxic time trial was caused by reduced motor output from the brain and not by fatigue within the working muscles.

Other new research has elucidated the mechanisms that operate in these situations.  A 2008 study published in the European Journal of Applied Physiology tracked muscular and cerebral oxygenation levels in volunteers as they performed an incremental stationary cycling test to exhaustion. They observed a steady decrease in muscle oxygenation throughout the test, whereas cerebral oxygenation increased initially but then plummeted shortly before exhaustion occurred.  The study’s authors concluded that there findings were consistent with the notion that exercise fatigue is caused by a reduction in motor output from the brain that occurs as a response to central monitoring of the well-being of the organism.  Similar studies have confirmed that reduced oxygen availability in the brain inhibits the brain’s ability to drive the muscles and thereby prevents the athlete from exercising to the point where a critical oxygen deficit damages the heart.

The Speed Factor

I know what you’re thinking: “All that this fancy new science does is transfer the limiting site of oxygen consumption from the oxygen transport chain to the brain.  It does not change the fact that a robust oxygen transport chain is critical to endurance performance or the fact that strengthening this chain will enhance performance (by keeping the brain well supplied with oxygen at higher intensities, it appears).”  True enough. But there’s another limitation to the classical interpretation of VO2max that we haven’t discussed yet. That limitation is simply this: Another performance characteristic with an underlying physiology that is completely independent of oxygen supply predicts endurance performance as well as VO2max does. Let me introduce this other performance characteristic with an analogy.

Human endurance athletes are often compared to racecars. For the sake of this analogy, let’s suppose that a racecar has two main functional components: a fuel supply system and an engine. The maximum speed the racecar can achieve is limited by the maximum rate at which the fuel supply system can supply fuel to the engine and by the engine’s maximum work output in rotating the axles.  Increases in either of these factors will increase the racecar’s maximum speed only if it is not limited by the other factor.  For example, increasing the capacity of the fuel supply system will only make the car go faster if the engine has unused capacity for work output. But if the engine is already producing as much work as its design allows at a given rate of fuel supply, increasing that rate will have no effect on the vehicle’s top-end performance.

In endurance athletes the oxygen transport chain is the equivalent of the racecar’s fuel supply system.  But what is the equivalent of the racecar’s engine?  It is pure speed, which is, loosely speaking, a function of what exercise scientists call muscle contractility.  Somewhat less loosely, pure speed in the endurance athlete is the capacity of large numbers of muscle fibers to contract together very quickly and forcefully in a coordinated pattern. This characteristic is largely independent of oxygen supply and is an equally powerful predictor of endurance performance. To complete the analogy, increases in the body’s capacity to supply oxygen to the working muscles will not enhance endurance performance unless the muscles have the intrinsic work capacity, or speed, to use that extra oxygen.

In a well-known study, Heikki Rusko and colleagues at the KIHO Research Institute in Finland had a group of 17 distance runners perform a 20-meter sprint (which took them about 2.5 seconds to complete, on average), a VO2max test and a 5000m time trial. Now, a 20-meter sprint is a completely anaerobic effort.  You could do it holding your breath and your performance would be the same.  Whereas a 5000m time trial is an effort in which faster runners will come very close to or reach VO2max. And yet Rusko’s team found that 20-meter sprint times predicted 5000 meter times better than VO2max test results did. In other words, pure speed was found to be more important to endurance racing performance than aerobic capacity.

This finding should not be shocking, but it is shocking to the average endurance athlete who has been taught practically from birth to believe that the lungs, heart, blood, capillaries and mitochondria are everything and the neuromuscular system is nothing.  Because of this indoctrination we forget that the most gifted endurance athletes are just plain freaking fast—fast sprinters.  To cite a semi-arbitrary example, the current world record holder at 5000m and 10,000m, Ethiopia’s Kenenisa Bekele, is capable of running 400 meters in 46 seconds—fast enough to compete in international track meets at that distance.

In the general athletic population, it is believed that sprint athletes have a lot of fast-twitch muscle fibers and endurance athletes have a lot of slow-twitch muscle fibers. It’s a lot more complicated than that. First of all, speed comes not only from the muscles but also from the brain and motor nerves. In faster athletes, for example, motor signals travel faster from the brain to the muscles.  This characteristic is partly genetically determined but is also trainable. Furthermore, there are many different muscle fiber types, not just “fast-twitch” and “slow-twitch”. Indeed, it’s more accurate to think in terms of muscle fiber characteristics than muscle fiber types. For example, the characteristic of contractility, or the strength and speed of muscle fiber contractions, is an important speed characteristic, but so-called fast-twitch muscle fibers are not always more contractile than slow-twitch muscle fibers.  Similarly, oxidative capacity is a muscle fiber characteristic that supports endurance (sustained speed, really), but so-called slow-twitch muscle fibers do not always have greater oxidative capacity than fast-twitch fibers. The best elite runners have a nice blend of contractility, oxidative capacity, and other muscle fiber characteristics supporting both speed and endurance, and that’s really why the can sustain such high rates of speed.

One can’t have it all, to be sure. Muscle speed and endurance characteristics are mutually incompatible to a certain degree. That’s why the fastest endurance athletes are never the very best sprinters, although they are very good sprinters. The very best sprinters, for example, typically have very thick muscle fibers that are conducive to power generation but not to endurance because they are heavy.

VO2max Training

There is a lot of research demonstrating that training at VO2max intensity is a powerful way to boost endurance performance. For example, in a study by the French exercise physiologist Veronique Billat, a group of runners increased their VO2max by 10 percent (that’s quite a lot) in eight to 10 weeks after adding twice-weekly VO2max interval sessions to their training. The rationale behind these sessions is that challenging the limits of the body’s oxygen consumption capacity in training is the most effective means to increase that limit, which, the conventional wisdom holds, is the key limiter of endurance performance. If this is true, is it not beneficial to determine one’s VO2max through testing and then use this information to train at VO2max intensity and thereby improve faster?

Well, we have already seen that VO2max, in the sense of oxygen supply capacity, is in fact not the key limiter of endurance performance. It is important, but it is not the be-all, end-all. Pure speed is just as important, and other research has shown that speed-boosting training modalities such as plyometrics improve running performance when added to an otherwise “aerobic” training program as much as VO2max training does.

Nor is it necessary to know your VO2max to reap the benefits of VO2max -type training. It is enough simply to “run hard” by perceived effort in classic VO2max interval workout formats such as 5 x 3:00 with 3:00 active recoveries. Because VO2max is always changing in response to training, anyway, you would have to submit to frequent testing to ensure that you performed such workouts at precisely VO2max intensity even if such precision did matter.

Generally speaking, there is nothing magical about physiological “sweet spots” such as VO2max and lactate threshold. Research has shown that endurance athletes tend to improve most at the speeds they focus on in training. Training at VO2max speed improves performance at that speed more than training at any other speed does, but it will not improve your performance at any other speed (say, 10 percent slower than VO2max speed) more than training at that other speed will. So the only circumstance in which it would be especially important to focus on VO2max intensity is if it happened to correspond to your race speed for a given race distance. But even then you could ignore the underlying physiology and simply train by speed.

A version of this article appeared originally in Inside Triathlon.