Monday, September 19, 2011

Simple Sugars… I think not!!

It could be said that carbohydrates are an endurance athlete’s best friend. Without them we would fatigue and be unable to sustain the 20,000 or so muscle contractions it takes to complete a 4 hour ride.  Physiologically speaking carbohydrates (CHO) are the main fuel source (combined with fat) to supply energy to not only skeletal muscle but also the brain, nervous system and cardiac muscle. Although we usually consume CHO to support muscle contraction and maintain blood glucose there are a few intriguing roles of CHO that many athletes are not aware of. 

Generally speaking the rate limiting step in getting CHO to the muscle is the absorption from the gut into the blood stream. Carbohydrates come in various forms. This includes small and simple CHO such as glucose, fructose and galactose which are all monosaccharide’s.  Bigger more complex CHO take longer to absorb as they are by nature more complex and take longer to breakdown before being absorbed. Under laboratory conditions we know that during intense exercise skeletal muscle can oxidise glucose at a rate much greater than we can absorb it and until recently the maximal rate of exogenous (consumed) CHO oxidation was thought to be ~1g/min.

In a study that has now seen the development of a well known brands ‘C2max’ energy gel formula researchers experimented with using multiple carbohydrate mixtures to see if they could increase the absorption rate when compared to glucose alone. Interestingly when they combined glucose with fructose they found that absorption could be increased by ~50% which then resulted in a significantly greater rate of exogenous CHO oxidation at the muscle (~1.7g/min). This finding was attributed to the possibility that glucose and fructose have different transporters across the gut wall and they coined the term ‘multiple CHO transporters’, which has had much interest over the last few years. For a more in depth insight into all this check out

These same researchers have discovered an even more interesting fact about CHO that could have significant performance benefits for a range of athletes. As already discussed CHO is the primary fuel source for muscle contraction during high intensity exercise however, it appears that CHO may also play a role via centrally mediated mechanisms. By ‘centrally mediated’ I refer to the complex role of the brain and its neural control over skeletal muscle. In a study that looked at the effects of intravenously infusing glucose versus the traditional oral ingestion of glucose on cycling time trial performance an unexpected finding was revealed.  These researchers observed that the distance covered during a 1-hour time trial was significantly greater under the conditions where subjects ingested the glucose orally. They developed the hypothesis that there may be receptors in the mouth that can sense CHO and can positively affect the brain in a way that enhances performance.

Since this first study there have been a multitude of studies completed to further investigate this remarkable role of orally ingesting CHO. It has even been shown that mouth rinsing a CHO solution then spitting it out (without swallowing any) enhances performance. These studies have confirmed that; 1) Certain areas of the brain related to motivation respond to CHO in the mouth, 2) It is the calorific  (energy containing) characteristic of CHO that trigger these receptors because an artificially sweetened solution does not have the same effect and 3) It appears that the duration the solution is rinsed in the mouth is important.

Although much light has been shed on this topic there are still a few small things we are trying to figure out. It is not yet clear if this mouth rinse procedure still has an effect after a meal high in CHO has been consumed. Because most research studies require subjects to come into the laboratory without eating breakfast (fasted) we are not sure if under real life circumstance where an athlete would eat breakfast before an event if the rinse procedure is still effective.  This question is currently being followed up by RMIT researchers in collaboration with the Australian Institute of Sport in hope that they can provide a clear set of guidelines for athletes competing in the 2012 London Olympics.

If you are interested in being a subject for this study you can contact

Wednesday, July 13, 2011

Is speed a mentality?

Ive just recently returned from Europe were I fulfilled a long time dream of seeing the Le Tour in the flesh as opposed to from my couch. The little that I saw made it clearly evident that this race is huge, I mean massive in a way that TV does it no justice at all. The racing itself is only a small portion of what is going on at anyone time. My fetish for all things carbon was completely overloaded and so was the memory card from my camera that nearly went into melt down because I  had a need to capture anything that had 2% body fat or 2 wheels. Esthetically all tour related things are beautiful (except Cadel....sorry Cadel) which of course is the goal of sponsors and teams to make us all lacking in genetic grace want these beautiful, fast, light, sexy pieces of extreme engineering to make up for the performance deficit (I am talking about the equipment not the riders).

As seen in the above photo (bonus points if you can figure out which Schleck brother it actually is) even the riders have to look good. If you are familiar with Zoolander you will recognize the Blue Steel pose. Getting to the point... How much of performance is actually limited by skeletal muscle? Id swear that if I is was asked to fill in for a team during the TTT I would ride faster than I ever have before (until I eventually got dropped). And of course as many of us know getting a state of the art new bike seems to provide this motivational advantage that allows performance enhancement to exceed that of any mechanical advantage.

Ultimately, muscle is controlled by the brain and the brain is so complex that we haven't even scratched the surface of its capabilities.  There is a lot of sports science research that has attempted to determine the mechanisms of this central role of the brain in limiting performance. The simplest  example I can think of is the placebo effect that us scientists go to extremes to control and suppress. If you think you can go faster then you usually do. Performance appears to be a state of mind rather than a physical state especially when you have exhausted your adaptive potential through years of consistent training.

So is it possible to trick the mind into thinking you are an elite athlete? I would like to do a study where I hypnotize my subjects to make them think they are grand tour riders with the ability to put out huge power numbers and then make them perform a performance trial. My hypothesis would be that skeletal muscle would still be a limiting factor, however their would be significant improvements in performance compared to a control trial where the subjects performed it in a normal state.

My conclusion to this post is buy the most expensive fastest bike you can, live a life style that makes you think you are a professional cyclist, make sure you look pro every time you ride (even if it is on the trainer in your lounge room) and most importantly believe you are the fastest!! 

Think fast... GO FASTER.    

Sunday, March 20, 2011

Time Trial Performance - Call for Volunteers

Do you want to improve your Time Trial Performances?
Can you spare 1 morning per week?

Then....Be like the Pro's and get paid to train!!

I am currently recruiting for an upcoming research project entitled; The effects of a carbohydrate mouth rinse on cycling time trial performance commenced in a fed or fasted state. We all know the importance of carbohydrate (CHO) during endurance events. It is the main fuel source at intensities above ~ 60%max and we only have a limited supply. The body stores enough carbohydrate in the liver and muscles to last ~2hrs. Any event lasting longer than this that is performed at a moderate to high intensity requires CHO to be consumed to supplement supply from the liver and muscles.

Surprisingly though, it has been shown that even during high intensity short duration exercise (<60min) when CHO stores are at no risk of running out, consuming CHO can improve performance. This observation has been put to the test using various cycling time trial models. It is believed that there are receptors in the mouth that can sense CHO and relay messages to the brain that help improve neural output to the muscles. This has been proven using medical imaging techniques of the brain. One study measured the brains response to a CHO drink compared to a non-CHO placebo. The CHO drink caused certain parts of the brain that are related to muscle control to become active and we believe it is this link that allows an increase in self selected intensity.

To test this performance enhancing effect a little further my next study requires a group of subjects to perform a series of 1hr cycling TT under several different conditions. Our research is carried out at RMIT University in our Exercise Metabolism Laboratory at Bundoora (Melbourne, AUS). For this I need 12 willing participants to complete one TT per week for 6 weeks. Subjects need to be male, aged ~18-35 and be currently riding >250km/week. Subjects get paid upon completion of the trials, undergo full VO2max testing and receive numerous physiological and cycling performance reports. It past similar trials have been a great experience for myself and the subjects to get some great TT experience and learn some ways to improve performance.
If you think you have one morning per week free and an interest in participating then please contact me at

Tuesday, February 22, 2011

Research - The best type of Training

Ive always been interested about how things work. Ive often destroyed a perfectly functioning piece of gadgetry trying to determine the mechanisms of  its inner workings. I am now completing a PhD in exercise science trying to unravel the mysteries of the human body, and in particular skeletal muscle. I could talk all day about the mechanisms of how muscle responds to various nutritional and exercise stimuli, and am lucky enough to have the opportunity to document my understanding of such things in my forever expanding thesis. For scientists to understand these mechanisms we devise well controlled, meticulously planned research trials that require volunteers from the general public to perform various tasks within the laboratory so we can collect data and begin to draw conclusions. Who are these volunteers? They are people like you.. and often the hardest part of such research is generating interest and recruiting volunteers. Depending upon the study we will target a specific type of athlete. In general I use well trained cyclists or triathletes as they are familiar with the type of training and testing I use to measure adaptation and performance changes in response to specific interventions. My most recent study required 12 well trained cyclists to complete 4 different trials over 4 weeks to measure the effect of caffeine ingestion on cycling power output under conditions of normal or low muscle glycogen content  (I will make this the topic of an upcoming blog). Apart from being poked, prodded and yelled at to squeeze out every bit of performance possible  being a guinea pig in the research lab is often just a well catered for training session. And yet it has the added bonus of undergoing some physiological testing that if completed outside of a research scenario would possibly cost hundreds of $$$$$. So for a little effort and commitment you could actually be paid to train, yes... there is often financial reimbursement for your time and effort plus you get some very handy physiological feedback. By now I hope I have inspired a little interest in my readers. Although my intentions are to educate, they are also to open some avenues to help me entice a new batch of enthused athletes to volunteer for some up coming research. Next on the books is a study investigating the effects of a glucose mouth rinse on 40km TT performance. Although many athletes are aware of the benefits of carbohydrates during exercise many are unaware of the multiple mechanisms of its actions. Apart from being a substrate for muscle contraction it is also becoming evident that carbohydrates can be sensed by receptors in the mouth that ultimately send signals to the brain that enable us to work harder for longer. Our new study is targeting this action and testing it using four 40km TT performed 1/week over 4 weeks. For this I need 12 cyclists/triathletes to perform each of these sessions. So if you have an interest in research, want to dramatically improve your TT performance and have the luxury of a paid catered training session then here's your chance. For further information about participating send me an email at

Wednesday, February 16, 2011

The Boundaries of Size and Speed

I do like to day dream. If you slip far enough away anything is possible. I find myself on occasion dreaming of being a genetic endurance freak with the ability to leave my competition gasping for air while I ride away into the distance. Unfortunately, no such luck occurred at my conception and I am left to only dream. Amazingly though such people do exist. Hard work and a little dash of super DNA rounds out the top 10 at most of the grand tours. But yet even beyond these supreme endurance athletes are a small group of actual genetic freaks. The images above, well in particular the rather large whippet dog and the bull of all bulls actually suffer from a disorder where the hormone that regulates muscle mass is not present. This mysterious hormone called Myostatin is produced in skeletal muscle and then circulates around the body to regulate muscle mass. In ordinary individuals no matter how many hours they spend in the gym eventually they reach a level where their muscle mass plateaus. In the case of a genetically modified mouse or a naturally occurring dog there is no Myostatin present to regulate muscle mass so it continues to grow even without any major stimulus. In human cases there are reports of young children with super human strength and a six pack to die for, but yet I am not overly certain of the life span of these fortunate or possibly unfortunate individuals. My day dreams slightly stray from the realms of huge muscles but rather dwell on a VO2max somewhere in the theoretical realms of the spawn of Lance Armstrong (no introduction needed) crossed with Chrissy Wellington (3 x Ironman world champion who goes as fast as most of the guys). So.... what does regulate our ability to uptake and utilize oxygen? Are there individuals who are unknowingly sitting on the couch with the potential to hold 800W for a 40km Time Trial, Possibly? We believe that this potential is partially regulated by the fact that the larger the muscle cross sectional area the further oxygen has to diffuse from the circulation to the center of the muscle and this process is ultimately dictated by the laws of physics. There are of course alternative ways to achieve superhuman performance. Doping is probably the most common and simplest of these forms of performance enhancement. If only they sold EPO at the supermarket, but yet I suppose then everyone would be on it and we would be back at square one again. All in all scientists are still yet to accurately define what exactly limits the boundaries of human adaptation, at the moment I believe the majority of it lies in our minds!!

Thursday, January 13, 2011

The Ultimate Power

I used to think I was cool because I was one of a few that used a power meter on my bike. Those days are gone and it now seems everyone has one. Those who have handed over the coin for one of the various models I'm sure quickly realized the benefits and hopefully improved there training once they understood what the numbers (Watts) were all about. Power is a wonderful thing, especially for an exercise physiologist who is addicted to data. Power is essentially energy measured in Watts so if you are putting out 60 watts you could run a standard 60W light bulb, push a little harder and you could possible run your new LED TV for a while!! Interestingly cycling power output is directly related to oxygen consumption. If you correlate the two during an incremental test you can predict oxygen consumption using power with ~96% accuracy. There is also a linear relationship between power and oxygen consumption. If you know the power you can hold for ~4mins you can predict your VO2max using the equation;

Peak Power Output (4min sustainable power) x 0.01141 + 0.435 = VO2max (L/min)

All you need to do then is multiple the VO2max (L/min) by 1000 to get it into milliliters then divide it by your body mass (kg) and you have a number pretty close to your true VO2max (mL/kg/body mass/minute). This value is probably the value you hear everyone talk about if they have had it tested in the lab. For comparison sake a sedentary individual usually has a value around 30-40. A good age group athlete will be 50-60, the guys/girls winning on the weekends will be 60-70 and an elite athlete will have a VO2max of probably >70. Genetic freaks like Cadel and Lance are up around 90. Although VO2max is a good predictor of performance it is not always correct. There are plenty of athletes that I have tested that score lower than me yet smash me on the road or track!!

OK.. Now back to power. Power is good because it is instantaneous unlike heart rate so when prescribing exercise intensities it is far more accurate and easier to use correctly. Anyone who uses programs like Training Peaks will know their highest held power over increments of time. It calculates it for you then allows you to compare your results with others, this is usually done using Watts/kg.body mass because it makes it all relative. Watts/kg also allows a good picture of possible performance for various athlete types. Absolute Watts is often a good predictor of Time trial performance on a flat course, however once gravity is involved W/kg becomes far more important. A good climber should probably be aiming to be able to hold close to >5.5W/kg body mass going up hill for an extended effort (20-30mins). Some of the data over the years from the Tour de'France has shown Lance in 2004 holding close to 6.97W/kg going up Alp de'Huez on a climb lasting close to 1 hour!! Interestingly for a few presentations Ive done I predicted Lance's VO2max using the equation I mentioned earlier. It went something like this;

If Lance is holding 6.97 watts/kg and he weighs 70kg he averaged 488W. Assuming Lance is holding about 80% of his peak power (which I've chosen from observation) then Lance's Peak 4min Power would have been about 610W. Now.. Using the equation (610x0.01141+0.435) we get a VO2max of 7.39L/min. Multiply that by 1000 and divide by his body mass we get 105mL/kg.body mass. As many possibilities for error this prediction has I try to use it to possibly show a superhuman performance

For a typical cyclist monitoring power data is probably the best and easiest way to track performance over a season or lifetime. Ive been striving now for about 2yrs to get my peak power above 400W. Slowly, (but not yet) i am getting closer to this goal. However, looking at it relatively I hit a mile stone leading up to this years Tour of Bright by finally reaching a  power to weight ratio of a fraction over  6W/kg. Still by no means comparable to the worlds best but good enough to leave most of my riding buddies struggling to hold a wheel when the road goes up.

All in all power is becoming common place in cycling. If you want to brag about how high your power was at the coffee shop after the bunch ride then you've got to do your time at the front because sitting in will save you somewhere in the vicinity of ~30% when compared to the guys pushing the big numbers on the front!!

Tuesday, January 11, 2011

Exercise Nutrient Interactions

Although many of us are aware that certain nutrients are essential for good performance and recovery from exercise it is often overlooked that by manipulating certain dietary components we can alter or even enhance adaptation to training. When we talk about 'nutrients' we are generally referring to the three macronutrients carbohydrate, fat and protein and more importantly how much we need of each to sustain a healthy body and promote adaptation. As endurance athletes we are mainly concerned with carbohydrate (CHO) and to a lesser extent fat (FAT) whereas anyone partaking in resistance training will preach all about protein and its benefits for muscle hypertrophy. In the past sports nutritionists have stressed the importance of a high CHO diet for athletes to be able to maintain high training intensities and also maximize performance. As many of us have experienced when our body becomes depleted of carbohydrate stores intensity suffers and performance declines. This can either be acutely at the end of a long training ride/run or race situation or after longer periods of a restricted CHO diet. As soon as muscle (and more importantly liver) glycogen stores are below optimal everything feels harder. So.... most of us pay attention to these nutrition guidelines and consume high CHO diets to maximize recovery  but also eat bars/gels etc during prolonged exercise to avoid the dreaded 'Bonk' . Ok... Now for some science... If you've read my last post on training adaptation you will have noticed that the body adapts to physiological circumstances that cause cellular stress and sure enough running low on CHO stores is a major physiological stress!! There are a couple of studies that have very clearly shown that training with depleted muscle glycogen (glycogen is a stored form of glucose and glucose is a CHO) can actually magnify the training response. This has been termed as a 'train once daily vs train twice every second day' approach. In these studies subjects either trained once every day so that CHO stores could be replenished after each session (HIGH) or a second group trained twice every second day. This allows the group that trained twice every second day to perform the second exercise bout (usually ~2 hrs after the first) with reduced or low CHO stores (LOW). Both groups over a 3 wk period performed exactly then same amount of training but the LOW group performed 50% of training with reduced muscle glycogen. Amazingly after the 3 wk of training the LOW groups performance in a test of endurance and also several markers of skeletal muscle oxidative capacity were significantly improved compared to the HIGH group. So maybe we can now begin to recommend to athletes to undertake specific training sessions with reduced muscle glycogen and lay off those high CHO recovery meals.

The Molecular Basis of Training Adaptation

It amazes me every time I ask the question to my athletes 'what happens in the body as a result of training that makes you fitter and faster?' No one seems to be able to give me a reasonable answer so I thought I might post a topic that might help explain this deep physiological mystery. Of course there are several components that make up performance but our performance potential is basically limited by our physiological capacity dictated by genetic predisposition. As endurance athletes we are typically limited by skeletal muscle parameters coupled with the cardiovascular system. You may have heard that world class athletes are the way they are because they were lucky enough to have good genes. This is partially true. The human genetic code is basically the same for everyone however some fortunate individuals express specific genes differently. Confused yet? Ill explain... The physiological system of the human body (and any living organism for that matter) is capable of adapting to it's environment. As such when a stimulus is applied (ie, training or running away from a dinosaur) the body does what it can to make sure that next time such a stressful event occurs it is better equipped to deal with it. If you want to understand the big picture you have to think small. Each cell of the body contains the entire genetic code and depending upon the cells role (eg. skeletal muscle, bone or red blood cell) it will express different genes within the genetic code. So each time the cell is stressed certain molecules called transcription factors stimulate certain genes. The primary role of a gene is to encode the sequence to make new proteins and it is the proteins that enhance the cells functional capacity. For example the contractile elements of skeletal muscle are made up of specific proteins that when assembled together form actin and myosin. Actin and myosin have their own specific sequences which is encoded into our genes. When we perform resistance exercise (I'll use this as an example instead of endurance training because its easier to visualize) we stress the muscle cells, activate transcription factors which then stimulate their specific target genes. These genes release the code for the proteins and the cellular machinery can then form these proteins together to form more functional equipment like actin and myosin. So if we repeatedly perform resistance exercise we are continually repeating this cellular process which with time results in more contractile proteins (actin and myosin) and thus bigger muscles. The same goes for endurance training except the proteins made are responsible for using oxygen to break down carbohydrate and fat for energy. So if this process is the same for everyone why haven't I got an Olympic cycling gold medal yet? I train just as hard as those guys! Well.. those guys are lucky because there are other process that display variance between individuals that dictate the upper limits of how much adaption should occur and these are basically set at a higher level for 'genetic freaks'. Without these boundaries we would otherwise from my previous example continually grow muscle and end up as some Hulk like creature with biceps so big we are unable to bend our elbows enough to get food into our own mouths. So.. train regularly to make sure you are continually stimulating new proteins but remember the triggers for these proteins are specific so your training must reflect the way you wish to adapt. Unfortunately there are many inhibiting pathways that regulate why endurance athletes with all of the hours of training they do don't stimulate muscle growth (which would possibly inhibit performance) as well as oxidative capacity. It's called specificity!!!