 So, some of you may have noticed the acronym BFR appearing on some sessions, especially in Strava, for several athletes that you may know, including myself.
Why mention this is because there’s been a number of questions that I have received from both athletes that I coach as well as weekend warriors who are keen to understand what BFR actually is. It seems that as soon as you post anything on Strava, the stalkers start wondering if there some special sauce that they are missing out on. In this instance THERE IS some special sauce. But let me make it clear from the outset that this is NOT for everyone and more importantly needs to be done in a very controlled manner to not elicit any injury. So, what is BFR? BFR stands for blood flow restriction (otherwise known as occlusion training). For those of you that frequent the more popular gyms, may have seen some weightlifters walking around with what seems to be a tourniquet around either their arms or their legs. This is kind of where BFR has its roots. A number years ago it was shown that by occluding the muscle by the use of a tourniquet (only occluding venous blood flow!) you could obtain close to the same benefits by lifting only 20% of the maximum weight. So instead of beating yourself to a pulp in the gym by lifting heavy weights, you can achieve up to 90% of the same gains by only lifting 20% of the normal weight that you would lift. That obviously led the exercise physiologists to consider whether a similar response would be seen in endurance training. Again, let me point out that the application of BFR in endurance training is very very new. I’ve been following it and testing it out over the last 12 months, but it is an emerging field. To date there are a number of studies showing benefits to the endurance athlete, but again very specific responses and in very specific conditions, which I’ll touch on a little later. So firstly, an overview of some of the research (I’ve just picked out two over a good number of research papers):
That’s impressive! What exactly is happening in the body that causes this response – time to geek out! During occlusion training, the Type 1 and 2a fibres are starved of oxygen decreasing their work capacity. This increases a neural stimulation to other fibres of the same type that may be inactive and increases motor recruitment. That is to say when we actively contract the muscle, we only ever activate a percentage of its contained fibres. The percentage activated will vary from person to person but will never reach 100% of the muscle. By activating more fibres through occlusion training, we are better able to train more of the muscle to the demands of our sport than we would likely be able to through standardised training alone. Once the Type 1 and 2a fibres are depleted and fatigued, we recruit Type 2b fibres to continue the exercise in the absence of oxygen. This lack of oxygen creates a hypoxic environment within the tissue causing the release of Vascular Endothelial Growth Factor (VEGF). This signaling protein chemical is responsible for the creation of new blood vessels and their supporting networks. Blood vessels once complete will increase the surface area ratio of diffusion within the tissue allowing more oxygen and key nutrients to the tissue in the future along with increased lactate threshold. With occlusion training reducing levels of oxygen available to working muscles, a lactic acid/lactate build-up occurs dramatically quicker than expected. This chemical soup build-up is counteracted by the body converting it back to pyruvate. But with training, the body is better able to hold off and endure this acidic state for longer periods of time. While more applicable for those completing High-Intensity Endurance Exercise (HIEE), the applications of occlusion training are useful for a variety of sports. So that sounds all great, let’s go and purchase occlusion cuffs and start starving the muscle of oxygen! Well not exactly! This is where it becomes a lot more complex on how and when we should be using BFR to elicit adaptations. Again, let me just state that BFR tends to give close to the same level of improvement as normal training. But that’s the catch it’s not as good but rather only gets close to normal levels (although we can manipulate some responses that we wouldn’t get out of training, but this is athlete specific) Some of the applications we would use it would be
If we know that you suffer from a venous occlusion (thanks to Moxy testing) then yes BFR may be a way to increase plasma volume and elicit additional adaptation over and above your normal training. I’m not going to get into the detail around the training protocol and how to apply BFR. Pressures and application are extremely important and to a point specific to the person and session, hence rather reach out to me if you want to know if this is for you,.
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 As the longer events on the calendar start creeping up to us (especially Desert Dash, Double Century and the Munga), I want to take you through why we do heat acclimatization with our athletes and what the benefits are.
Although this is may be directed to our ultra athletes racing at the end of the year, it is as applicable to the events in the calendar next year, such as the Epic, Attakwas and to be honest any race in the heat (actually any main race!) Interestingly enough you will see later on that heat acclimatisation has the same benefit as training at altitude, so this can be applied to all major events that you may be doing. Remember though, the body has a wonderful way to adapt, so by doing too much training in the heat on an ongoing basis, the body will eventually adapt so that no benefit will be seen. So, heat acclimatisation for performance improvement needs to be a PLANNED approach. So, let’s start with some of the research behind heat acclimatization. One of the first studies was in 2010 that showed elite cyclists that trained in the heat for 10 days had a performance increase of 6 to 8% in the time trial over a 60-minute period. Those are some big gains. The problem with most of us is that we cannot spend 10 days sitting on our bikes in succession during the hottest periods of the day. Researchers then started to turn their attention to how external heat from other sources could impact performance. This led to a number of research papers around training without fans, training in a sauna, sitting in a sauna, and more recently sitting in a hot bath. What was found was that the best approach with regards to performance improvement was actually sitting in a hot bath. This gave similar performance improvements that were seen in the original 2010 study. (I’m not going to go into the detail of how heat acclimatisation changes your body, the big improvement in physiology is the increase in plasma volume after heat acclimatisation as well as being more tolerant. If any of you want to understand the detail reach out to me) Now even more interesting was a very recent study that compared altitude training with heat acclimatisation. In summary the outcome of this study showed that heat acclimatisation was as good and in some instances for certain individuals even better than doing altitude training. So, train high, sleep low may have to change to train hot, race cold! What we have found over the last two years plus is that we have been using heat acclimatisation with our athletes, is that based on certain physiological parameters such as the VO2 percentage, male or female, and acclamation history each person needs to have a slightly different protocol to maximize the benefit. Last but probably most important……., since I mentioned above one of the major benefits is the improvement in plasma volume is that it is extremely important to make sure that during the event plasma volume stays at those elevated levels. That means hydration is CRITICAL. You all know my view around what product you need to be using to keep up properly hydrated. If you become dehydrated your heat adaptation will basically become zero. So, stay hydrated. So, in summary: · heat adaptation can give improvements are between 5 to 8% (more pronounced in hotter conditions) · hot baths seem to be the best way to apply the stress (between 5 to 14 days) · the exact protocol will be based on your physiology - a two stage approach may be more beneficial · hydration is critical during the event to maintain the adaptation · the benefits of heat adaptation are seen irrespective if the race is held in hot or cold conditions “With a week to go to my main race, what’s the best workout I can do to make sure I’m prepared?” is a question I get asked often by athletes looking for that final edge. My answer…..“Uhh….sleep!” Not exactly the answer most people want to hear, but to be frank, one of the most underrated performance enhancers that you will come across. And its free! A recent study on cyclist (Extended Sleep Maintains Endurance Performance better than Normal or Restricted Sleep) showed that an extended sleep of 8 hours improved time trial performance of up to 25%! Sleep deprivation on the other hand, seen as just under 5 hours, led to a decline in performance of up to 30%  Clearly, being sleep deprived negatively affects performance. But even if you feel like you’re getting enough sleep, it’s possible even more could still increase performance. A study out of Stanford tested basketball players after 5-7 weeks of increasing their sleep to 10 hours per night. The results? Shooting accuracy improved by 9% across the whole study, while sprint times dropped by an average of one-tenth of a second. Not only that, but all players subjectively reported better mental and physical well-being during training and games. Your body has two different central nervous systems settings - sympathetic and parasympathetic. The sympathetic nervous system releases energy and adrenaline, elevates heart rate, and increases arousal and focus. Your parasympathetic nervous system, on the other hand, signals rest and relaxation, which is critical to sleep. During training and competition, your body is locked in to that sympathetic nervous system. It’s necessary for high performance - you need the extra blood flow and attention to react quickly. However, overtraining, poor lifestyle choices, and too little sleep can keep you in that state, limiting your ability to calm down. Aim for those 8 hours of sleep in the week leading up to an event. You may think you can catch those hours up by napping. Well not exactly. Napping will help, but again research shows us that performance will still be less than if you get a full 8 hours sleep So make sure you get some shut eye leading into your event….it can cost you up to a 30% decrease in performance. Those of you that have done the INSCYD metabolic lactate test, have now a measurement for both FatMax as well as CarbMmax. Both these are an indication of how efficient you are at burning fat as well as the efficiency to utilize carbs.
So to jump straight into it, let’s have a look at FTP. Over the years FTP has become the gold standard to measure both fitness and to model performance. Except there is one major flaw - FTP is only relevant in the presence of an energy substrate that can generate enough ATP (the fuel you muscles use) to keep up with the demand from your muscles. The only energy source that can do this is CARBS! So in short as long as you can burn a high enough amount of carbs for them to be utilized efficiently in your body, your FTP will be of value. BUT as soon as you run out of carbs, FTP becomes technically irrelevant. A quick deep dive............Most of us even pedaling at half or 50% of our FTP will utilize in the region of 50 to 60 g of carbs per hour. As you increase the intensity to anywhere between 80 to 90% of FTP the usage can increase to between 160 g to 200 g per hour. The body can only absorb between 60 to 90 g of carbs per hour. The 60 to 90 depends on a couple of factors, what kind of carbs you are using, how efficient your body is absorbing carbs, whether you are keto adapted, and how damaged or undamaged the mitochondrial in the muscle are (So most of us never really gets to 90 g, more like 75 g)). So if you’re burning at race pace (just below FTP) lets say 180 g per hour, but can only take in maximally 90 g per hour, that means there is a deficit of 90. Luckily the body does store carbs and there is anything between 350 to 500 g, stored both in the muscle as well as in the liver. So as the hours tick by the deficit of 90 g is offset by the stored carbs/glycogen in the body. You can do the math, that will give you 4 to 5 hours of energy before you hit the wall. Again that is assuming you can absorb the high end of 90 rather than the low end of 60. The ONLY solution at this point is to either use fat as a fuel or to slow down the point where carbs in equals carbs out. (again if you've done a INSCYD test, you know where that is) As long as we can feed the muscles with carbs we can perform at or close to our FTP. Unfortunately when carbs run out the only energy substrate available to us is fat. Fat is a lot less efficient and hence it’s broken down and utilized at a much slower rate than carbs, which means the bottleneck in the muscles becomes how efficiently we can break down and utilize fat - the quicker you can break down and use fat, the quicker the muscles respond! Anything less than a 3 hour race FTP is relevant, and the main metric to consider when trying to simulate performance. However as we get to the depletion point of 4 to 6 hours, FTP becomes irrelevant rather less relevant and fat utilization becomes the better metric to consider. A quick real life example - Two athletes both with the same FTP, both the same weight riding on the same course. In the past the assumption would be made that both athletes should finish together because of there FTP. However if one athlete can utilize fat better, it means firstly they are able to conserve the carbohydrate stores in the muscle, and secondly once those are depleted that the better utilization allows more energy to be available for the muscles to perform. In summary the athlete with a higher fat utilization, would be the athlete that performs better in a longer distance event. Have a look at the example below, these are real numbers looking at two athletes that have a similar watts/KG -
So athlete one has a higher watts per kg, so would be expected to be the better performer. However his fat utilization is only 5.3kcal, and the maximum effort he can put out once his body has been depleted (with taking in 60 to 90 grams of carbs per hour) is 2.6 w/kg. Now look at athlete two, a lower FTP w/kg, but much more efficient in utilizing fat (and conserving carbs). Once they run out of carbs, they can keep a pace of 3.1 w/kg. That’s a massive difference! And by the way athlete two is a woman! You starting to see why some women start to close that gap to the leaders as the race goes on…… So who would you bet on winning a 2 hour race and who would you bet on winning a 20 hour race?? So as you can see FatMax becomes a very relevant metric with regards to performance in long distance events. The next question you should be asking is can FatMax be trained? The simple answer is yes!
Hope this helps you get a better understanding of how important fat utilization is in long distance events. |
AuthorDion Guy - Exercise Physiologist and Pain Cave Founder ArchivesCategories |
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