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  1. Cycling is a fairly unique sport due to the ability to be able to get a direct measure of workload. Power meters have been around for a few decades already and are able to measure your power output in real time during training and racing. Immediately after the power meters were first released to the consumer market, they were extremely expensive and heavy, use was limited to certain professional cycling teams and others that could afford them. Recent advances in technology have seen power meters become cheaper and as a result their popularity has increased among cyclists of all levels. In this article, we will provide some insight into how we use power meters with our athletes. Click here to view the article
  2. There are really two ways in which your power meter can be used. Setting the training intensity during interval training. Most cyclists who are introduced to power meters fall under the mistaken impression that the most effective use for their power meter is in setting the intensity. However, this might not always be beneficial (which we will highlight below). Collecting data for analysis after your training. Cyclists love data and if we can measure it, we probably will. However, data is only really valuable if it is correctly interpreted. Power output helps cyclists and their coaches monitor training load and, most importantly, progression. Using the power meter to collect data for later analysis is the more effective strategy. Using the power meter to set training intensity: Before the advent of power meters, most elite cyclists used heart rate as a measure of training intensity. Heart rate in a laboratory setting is almost always linearly related to power. i.e. as power output increases, so does heart rate and the rate of increase stays consistent. It was therefore a useful way to set specific training zones based on a laboratory test done at the beginning of the season in a performance laboratory. However, out in the field (on the road or trail) there are many factors that affect the relationship between heart rate and power. These include dehydration, temperature, altitude, fatigue, caffeine intake, stress and body position. Together these factors can change heart rate by up to 25 beats per minute for the same power output. Power meters measure the amount of work done while cycling. Power output, measured in watts, is the product of force and angular velocity. Power is not influenced by environmental conditions, fatigue or any other factors, which makes it a less variable measure of intensity than heart rate or rating of perceived exertion. Does that mean you should only use power to prescribe training intensity? Although power is a very objective and reliable measure of intensity, doing intervals based on power may not be the most effective strategy. A study conducted by Dr Jeroen Swart at the Sports Science Institute of South Africa examined improvements when training by power or heart rate. They took 21 elite male cyclists and trained them using either power or heart rate prescribed interval sessions. Before and after a 4 week training period, the athletes completed a VO2 max and peak power output test as well as a 40km time trial. To ensure that they had all performed exercise at the same intensity, the average training power outputs and heart rates from all the training session for each group were compared. They were identical. When the performance tests were compared, the peak power output tests showed that the heart rate group had improved by over 5% while the power group had improved by only 3.7%. Analysis determined that the heart rate based intervals were 60% more likely to result in improvement than the power based intervals.If both groups trained at the same average intensity, how can that be? Well, another often cited deficiency of heart rate monitors is the lag between the increase in intensity of the exercise and the increase in heart rate. This can often be as long as 30 seconds. As a result, the heart rate group had performed intervals where the initial power outputs were very high in an attempt to get the heart rate up to the target. Later in each interval, the power outputs dropped off significantly, ending up much lower than that of the power group. The power group, as expected, churned along at an even intensity for each interval. The hypothesis is that this initial surge in the heart rate group could have been responsible for the extra training effect of using heart rate. That said, using power to prescribe training intensity can allow the athlete or coach to progressively increase the target intensity and when this is done appropriately, it can force greater improvements in performance. A power meter can keep you honest during your training and prevent you from soft pedalling during your intervals. If you see your power output starting to drop towards the end of your interval, you are more likely to try and put in a little more effort to keep it at the target wattage. At Science to Sport we use both heart rate and power to prescribe training, depending on the specific session. Setting the right intensity requires analysis of the training data to ensure progression and avoid excessive fatigue. Analysis of your training data: Power meters turn your bike into your own mobile testing laboratory The reliability of power output data you record during a training session makes it a great variable to be able to accurately measure and monitor improvements in training status. If you are able to produce more power over the same time interval, then you are responding favourably to your current training load. While speed up your local climb can be a used as a more crude measure of progression, it will be influenced by wind, temperature or trail conditions if you are on a mountain bike. Power meters turn your bike into your own mobile testing laboratory and allows you to perform your very own performance tests every time you repeat a standardised training session.Power meters are great for race analysis too. If you are working with a coach or perform all your analysis yourself, race data may allow you to determine what went wrong during your race. Did you go too hard too early? Did you make too many surges early on in the race that you paid for later? How did you pace yourself during the race? In addition, knowledge of the amount of work done (in kilojoules) during your training can allow you to fine tune your nutrition to ensure that your energy intake is matching your energy expenditure. How do you monitor training load with a power meter? Once you are recording all your training sessions with a power meter, you are able to plot an accurate Performance Management Chart (PMC). There are a number of different applications that enable you to plot a PMC; such as TrainingPeaks, Golden Cheetah and others. The variables plotted on a PMC include your chronic training load (CTL), acute training load (ATL) and training stress balance (TSB). These are defined in the glossary below.The PMC will give you a snapshot of your fitness (CTL) and how fatigued you are likely to be (TSB). How high a CTL to aim for is dependent on many factors such as your training history, age, work related stress and others. A top professional road rider might aim for a CTL of 100-130 while your mid 40’s exec / weekend warrior will be best off with a lower value such as 65 or 70. How can I ensure that my training load is sufficient? Analysing individual session data will be able to assist you in establishing if your current training load is sufficient to produce optimal gains. Analysing training data will allow you to assess progression. Are you managing to produce a higher average power output for the same interval session? If not, why not? Are you training too hard and not recovering? Do you need to train harder? That’s where an expert coach will come in. They have years of experience and often first hand knowledge through their own racing experiences to guide your training appropriately.As coaches we use a number of metrics to monitor external training load (the stress applied to the body), but also use other measures of stress to ensure that we don’t miss anything. An example is the Lambert and Lamberts Submaximal Cycling Test (LSCT). This and other tests allow us to measure the internal load (i.e. how you are responding to the load). In the meantime, avoid becoming obsessed with the numbers and remember to enjoy your riding as well. Glossary: Acute Training Load (ATL) is a 7 day rolling average of your TSS scores. The ATL can be loosely regarded as a measure of fatigue.Chronic Training Load (CTL) is a 42 day rolling average of your TSS scores and provides an objective measure of fitness. Functional Threshold Power (FTP) is the maximal average power output that you can sustain for an hour. This is the value that the PMC uses to judge the intensity and load of any training session. We at Science to Sport establish your FTP from physiological testing we perform in our laboratory, alternatively, a common method of measuring FTP is to do a 20min maximal effort and to multiply the average power of this effort by 0.95. Training Stress Balance (TSB) is the difference between CTL and ATL and provides an indication of ‘freshness’. Negative TSB values indicate that some acute fatigue may be present. Training Stress Score (TSS) is a score assigned to each training session to quantify the stress of the session. Riding at your FTP for one hour will produce a TSS of 100 points. The algorithms built into the PMC will assign an exponentially higher TSS for efforts that are above your FTP. About the author: Science to SportScience to Sport bridges the gap between scientific research and sports men and women in the field.Utilising scientific tools and experience gained through research and practical involvement at the highest professional and scientific level, the experts at science to sport are able to provide athletes with scientifically validated methods and products which they can use to their advantage during training and competition.
  3. Photo credit: Greg Beadle http://www.beadlephoto.com. What is a performance test? Performance testing can provide valuable information on the physiological characteristics that are associated with cycling performance. Testing can take place in a laboratory under controlled conditions, or in the field where the cyclist may be exposed to factors that could affect the outcome of the test (environmental temperature, road surface etc.). The testing procedure should provide the cyclist and/or their coach with useful feedback that can be used to plan subsequent training.It is critical that the testing protocol is both valid and reliable. A test is valid if it correctly measures what it claims to. In other words, a performance test for a cyclist should produce data that can accurately predict cycling performance. For example, a one repetition maximum bench press will have little value for predicting cycling performance. Reliability refers to how repeatable the results are. In other words, if we repeated the same testing protocol, on the same athlete, with the same equipment, under the same conditions, we would expect the same results. If a test is not valid or reliable, it will have little value for the cyclist. Laboratory-based testing is more reliable than field testing, simply because of the standardised protocol, equipment (accurate and calibrated), and constant environmental conditions. However, this does not mean that field testing should be abandoned. Standardised training sessions, such as an 8 x 4 minute high-intensity session, can be considered to be field tests. An increase in average power during these intervals could be valid measures of improvements in cycling performance. These field tests can track changes in performance and supplement the laboratory data which is collected less often. We use performance tests for the following: Profiling – Testing provides us with an objective measure of an athlete’s physiological profile. Monitoring – Testing at regular intervals allows us to assess the effectiveness of our training prescription. Training prescription – The training zones identified during the performance test are used to prescribe target intensities for training sessions. Determinants of endurance performance A laboratory based performance test will usually measure the variables below, due to the association of these variables and cycling performance. VO2max: The maximal oxygen uptake represents the highest amount of oxygen that an individual can consume during exercise. There is a strong association between VO2max and endurance performance. Lactate or functional threshold: The maximal intensity (power output or heart rate) that can be maintained for a prolonged period of time (~60 minutes). Peak Power Output: The peak power output is the average power output during the final minute of a VO2max test. Profiling Every amateur cyclist wants to know how they compare to the professionals and their local club mates. Performance testing allows us to provide each athlete with an objective measure of performance, which allows for accurate comparison between individuals.Unfortunately, not everyone can win the Tour de France, but performance testing can provide you with an accurate measure of your current performance level. This allows for objective ranking of cyclists, and can also indicate the gap to the next performance level. Data from a performance test also allows you to set realistic targets for yourself. As coaches, we know what is required of athletes to complete specific events. Once you have an objective measure of your current training status you and your coach can then sit down and determine what is needed to achieve the goal. Lastly, profiling can reveal the unique characteristics of an individual and may give insight into their relative strengths and weaknesses. This may help them target training to reduce their weaknesses or provide insight into which racing disciplines will suit that athlete. Monitoring Tracking performance improvements over a specific time period is another use of performance testing. The laboratory setting allows the sports scientist or coach administering the test to control the majority of the variables (temperature, external cooling with a fan etc.) that could have an influence on the results of the test. Regular performance testing allows coaches to monitor performance improvements made over the course of a single season or several seasons. This is one of the most valuable uses of testing and one of the many reasons testing needs to be done in a controlled manner under similar conditions.Regular testing should be completed using the same testing protocol, the same equipment, under the same conditions, so you can accurately track performance improvements brought about by training. This is always a good way to determine if the training is working or if you need to make a change in your training to introduce a new stimulus. Training Prescription This is often cited as the most important reason for anyone to undergo any form of performance testing. We know that each individual cyclist is unique and therefore training intensity prescription should also be unique. For example, Chris Froome has a maximum heart rate of around 174 beats per minute while Simon Yates has a maximum of around 199 beats per minute. The age-old formula of 220 – age to determine maximum heart rate, is not relevant to either of these individuals. A revised equation of 206.9 – (0.7 x age) improved the accuracy of the maximal heart rate prediction, but the most accurate determinant of maximal heart rate is still performance testing.These days many devices provide you with a predicted maximum heart rate, and training zones based on this predicted maximum. Once again, these training zones may provide you with a guideline for training intensity, but they can be greatly improved upon via performance testing. Researchers at Western State Colorado University recently investigated whether training according to percentages of heart rate reserve (HRR) was as effective as training according to the individualised training zones determined from performance test data. The group who trained according to individualised training zones showed greater and more uniform improvements in VO2max compared to the group which trained based on percentages of HRR. If you are interested in reading more, the full article can be found here. Performance testing, and specifically VO2max or lactate testing will allow you to determine individualised training zones based on the results of your test. You will then be able to train with more specificity according to your individualized zones. While other forms of testing can also provide training zones, VO2max testing is considered the gold standard when it comes to determining training zones. So now that you know why you should do performance testing, which test should you do? The most common types of performance tests done by cyclists include:Max test/ PPO test/ VO2max test Time Trial (20km or 40km) or FTP testing Lactate Threshold testing VO2max or PPO test As stated earlier, the VO2max or PPO test is considered the gold standard when it comes to performance testing. Data from this test provides you with individualised training zones which will improve your training through more accurate monitoring of your intensity. Photo credit: Greg Beadle http://www.beadlephoto.com. The VO2max test is conducted in a laboratory, which means that it is highly repeatable, giving it a major advantage over field tests performed outside of the lab. VO2max testing is often accompanied with body fat percentage measurements which allow you to track your body composition at regular intervals. These tests can be repeated at set time-intervals allowing one to accurately track performance improvements and the effectiveness of your training. A VO2max test should provide you with your peak power output, which is the average power output for the final stage of the test. If you train with a power meter this will give you and/or your coach a good indication of what sort of power output you should be aiming for during your high-intensity interval training. The VO2max test will also determine your lactate threshold. Your LT as a percentage of your PPO is an important determinant of endurance performance, and cyclists should aim to have an LT at ~80% of their PPO. Time trials or FTP testing Another common form of performance testing is fixed duration (20 minute) or distance (20 or 40 km) time trials. The data from these efforts can be used to derive training zones, especially for those cyclists who train with power meters. The 20 minute all-out effort is a common method used to determine functional threshold power (FTP). Simply multiplying the average power output from the 20 minute effort by 0.95 will provide you with your FTP.While evidence suggests that the 40km time trial may be a better indicator of training programme effectiveness than VO2max itself, the test is physically taxing and requires a high-level of motivation to maintain a high effort for the duration of the test. As with the 40km time trial, a FTP test is a good indicator of performance and is a relatively easy test to administer. However, there are some important factors to consider before going this route. Most importantly the setting in which the FTP test is performed. The FTP test is often performed on the road where it is extremely hard to replicate similar conditions from test to test. Differences in heat and humidity between tests reduces the repeatability of protocol. These variables need to be considered when comparing test results. Completing the test indoors, in a controlled environment will help improve the repeatability of the test. Pacing in a FTP test is critical too. Starting too conservatively or too aggressively will not be a true reflection of your ability. A few familiarisation efforts could help with refining a more even pacing strategy. Lactate threshold testing Lactate threshold testing involves taking blood samples from the ear lobe or a finger during a test that has several stages of increasing intensity. VO2 data if often collected simultaneously during the test.While lactate threshold testing can provide you with accurate training zones and a good indication of your training status, it also has several draw backs. One of the issues with lactate testing is the invasive nature of the test which requires blood samples at regular intervals. The analysis of the blood samples increases the cost of the assessment. There is also the argument of how long it takes for the blood to flow from the working muscles to the point at which it is being drawn. However, research has shown that ventilatory data (VO2 and VCO2) collected during VO2max testing, are able to identify the same metabolic thresholds as lactate testing without additional blood analysis. This provides another argument for using a VO2max instead of lactate threshold testing to avoid the invasive nature of the testing. The majority of South African universities and sports science institutes will offer a variety of performance testing options. If you are interested, contact them for more information. About the author: Science to SportScience to Sport bridges the gap between scientific research and sports men and women in the field.Utilising scientific tools and experience gained through research and practical involvement at the highest professional and scientific level, the experts at science to sport are able to provide athletes with scientifically validated methods and products which they can use to their advantage during training and competition. Get your questions answered by the Science to Sport team Ask any cycling training, racing or nutrition related questions to be answered in the Q&A with the Coaches podcast.
  4. Cross-country mountain biking or XCO (the acronym given to the Olympic discipline) has increased in popularity in South Africa and globally over the past few years. So much so, that famed South African artist, Jack Parow, even wrote a song about it, Eksie Ou. Poor attempts at humour aside, the growth of this particular cycling discipline can largely be attributed to its inclusion in the Summer Olympic Games in Atlanta in 1996. Click here to view the article
  5. When an Olympic medal is on the line, international sporting federations tend to direct resources to the discipline in an attempt to increase the chances of success. In addition to its inclusion in the Olympic programme, the UCI World Cup series and high-profile World Championships have attracted some big brands as sponsors. The increased financial support has led to international races being beamed across the globe to fans eager to see if a Swiss, French or Czech flag will be raised above the top step. In South Africa, the late Burry Stander’s success forced us to pay attention to XCO racing and paved the way for others such as Philip Buys, James Reid, Alan Hatherly, Candice Lill (nee Neethling) and Mariske Strauss among others. Pietermaritzburg hosted two UCI World Cup events in 2012 and 2014 and the World Championships in 2013, which brought the World’s best to our doorstep. Participation in the National XCO Cup series has also increased, not only within the elite categories, with more age-group athletes taking part in this exciting discipline. An XCO race is a mass start event that typically lasts between 90 and 105 minutes and takes place over numerous laps of a predetermined course. The course usually consists of climbs, technical descents and single-track. The intermittent nature of XCO requires specific physiological characteristics, which may differ from those required for success in other cycling disciplines. In this article, we will unpack what it takes to be a successful XCO racer. On your marks….. A single lap of an XCO circuit will have a large amount of single track, which may make passing slower riders tricky. Riders’ starting position is determined based on the ranking relevant to the specific race. Starting towards the back of the field will result in an immediate disadvantage, compared to riders who start towards the front and can continue to ride at their desired pace. Riders who are less-technically proficient may slow down their more skilled competitors, but more on the importance of skill later. The elite men start sprint at the 2015 Lenzerheide UCI World Cup. Photo credit: Bartek Wolinski/Red Bull Content Pool. Researchers at Massey University in New Zealand, performed a longitudinal analysis of the effect start position had on finishing position in UCI World Cups from 1997 – 2007. Their results showed that finishing position is highly dependent on start position. In addition, the researchers recommended that developing athletes, should explore strategies that could assist them in improving their starting position. One such method is accruing UCI points from lower level UCI races, such as National XCO Cup races and stage races, as opposed to only racing World Cup races. Talented, developing XCO racers should be patient and gradually increase their ranking over the competitive season, rather than expecting an instant increase in ranking position. The physiology of XCO Sports science researchers enjoy bringing athletes into a laboratory in an attempt to find associations between physiological variables and performance. In road, marathon mountain-biking and certain track disciplines, the relationship between these physiological variables and performance can be very strong. However, physiological variables determined during standard laboratory testing fail to predict XCO performance on their own. The main reason for this is the absence of an ‘XCO-specific’ test that can provide better insight into the rider’s ability to cope with the demands of the event. In order to better understand the demands on an XCO race, let’s take a quick look at how we produce energy during exercise.A very brief summary of energy production during exercise Lactate threshold (LT) or functional threshold power (FTP) are terms often used to describe the maximal average power output an athlete can sustain for approximately one hour (learn a bit more about using power for training here). When riding at intensities below your threshold, energy is predominantly supplied through the process of oxidative metabolism (aerobic metabolism), which takes place in the mitochondria, the little power plants within our muscle cells. Oxidative metabolism requires the use oxygen to produce energy from carbohydrates and fat. During longer endurance events, such as road or marathon mountain biking races, this is the primary process involved in energy production. Oxidative metabolism has a large capacity to produce energy, but it is not immediately activated and once activated, produces energy at a slower rate compared to other energy systems. By comparison, glycolysis (anaerobic metabolism), which also involves breaking down glucose, or its stored form, glycogen, does so without the use of oxygen. Although energy production happens at a far greater rate, when compared to oxidative metabolism, the energy yield is far less. Energy required for short intense efforts (< 2 minutes) will predominantly be produced via glycolysis. Glycolysis results in the production of two molecules of pyruvate and two hydrogen ions (H+ or protons) for each glucose molecule metabolised. Pyruvate can then enter the mitochondria of the muscle cells and be metabolised further via oxidative metabolism to produce yet more energy. However, if there are insufficient mitochondria and/or low levels of oxygen in the working muscle (due to a low levels of fitness), glycolysis could slow down or even stop. In order to prevent this, pyruvate is converted to lactate by absorbing the proton. This turns lactate into a type of proton shuttle. Remember that pH is a measure of proton (H+) concentration, so by absorbing the proton, lactate is reducing the acidity of the muscle cell rather than increasing it as previously thought. At high rates of glycolysis, lactate is pumped out of the muscle cells by specialised transporters, which results in an increase in the amount of lactate in your blood. One of the physiological adaptations to high-intensity training is an increase in the number of these ‘lactate transporters’ in our muscle cells, which allows us to clear lactate from the working muscles at a faster rate. Once in our blood, lactate can be transported to other muscles, which are working at a lower intensity, where it can be used to produce energy through oxidative metabolism. In the case of an elite XCO rider, the lactate produced in the legs may be used as a fuel in the muscles of the arms and upper body. Understanding which energy systems are involved in during a particular activity allows coaches to tailor training programmes that will ensure that the relevant energy systems are appropriately stressed. Creating sessions specific to a particular energy system will improve the functioning of that system and allow for greater energy production. Now that we know what the energy systems involved in energy production are, how do we measure/monitor them? Aerobic capacity Endurance or aerobic capacity is often determined by measuring two variables; VO2Max – The athlete’s maximal rate of oxygen uptake and use Peak power output (PPO) – Which is the final workload (power output) reached during a standard incremental test in a laboratory Both VO2max and PPO are usually reported relative to body mass (e.g. W/kg for PPO and ml/min/kg for VO2max), and both have been associated with XCO performance. These two measures provide athletes and coaches with an objective indication of aerobic or endurance capacity. However, despite the somewhat strong association between aerobic capacity and XCO performance, the stochastic (intermittent) nature of XCO racing places a high premium on anaerobic capacity. Anaerobic Capacity Initial research into factors associated with XCO performance were fairly unidimensional and only examined the association between data from standard VO2max testing (VO2max, PPO and LT/FTP) and XCO performance. Researchers quickly discovered that despite the strong correlations between these variables and XCO performance, a big part of the proverbial puzzle was missing. The intermittent nature of XCO racing means that performance will most likely be heavily reliant on an athlete’s ability to repeatedly produce a high power output. A recent study examined the association between intermittent power output, measured by a series of sprints with short rest or recovery periods and XCO performance. The study made use on an intermittent power test, which consisted of 20 intervals of 45 seconds of work and 15 second rest periods. The cyclists in this study also performed a 20 minute time-trial in order to determine their FTP (95% of the average power output for the 20 minute effort). The average power output for the 20 intervals and the FTP value were both divided by the mass of the riders in order to account for differences in body size. The cyclists then all took part in an XCO race and the relationship between relative FTP, IP and race performance was examined. Interestingly, the best predictor of XCO race performance was in fact the intermittent power test. While the association between FTP and race performance was strong, it was not as good a predictor of performance as IP was. The increased popularity and availability of power meters, means that intermittent power output can be determined from a field test or training session. For example, two sets of 6 x 40 second sprints with 20 seconds of recovery (A session commonly referred to as 40:20’s), can provide a useful performance predictor for XCO athletes. For coaches or self-coached athletes, including such stochastic or intermittent power sessions are also an ideal preparation for a XCO race. The coaches at Science to Sport regularly include such stochastic intervals, and measure performance and progression by analysing the normalised power (a weighted average of power designed to better represent the true physiological load) across the whole intervals set. Demands of XCO racing Power meters have also given us coaches the ability to closely analyse the demands of a XCO race. Although each XCO race will differ, typically an athlete will spend approximately 35% of the full duration of their race (approximately 90 minutes for elite categories) at a power output above their threshold. Approximately 30% of the full duration of a race will also be spent not producing any power. This occurs on downhills, or when coasting on flats or around corners. Therefore, sessions specifically designed to mimic these demands may be of great benefit to XCO racers.As a practical example, the 2016 South African National XCO Championships were help at Cascades MTB park. Each lap of this course consisted of two moderate length climbs or sections where approximately 60m of altitude was gained. The figure below represents the power data from one of our elite athletes for the first 15 minutes of the 2016 SA Champs. For watt/kg comparisons, this athlete weighs only 72 kgs. From the gun you can see that the athlete kicked out ~1300 watts and had to maintain 1000 watts for 18 seconds. This was followed by several spikes well over his threshold (demonstrated by the yellow dotted line). By the top of the first peak in the course the athlete had averaged 500 watts for 2:30 minutes. The second climb on the course is also very undulating, which results in several efforts far exceeding his threshold power. 10 Minutes into the race his average power was 354 Watts (this include all the downhills too) and his normalised power was 408 watts. The complete opening lap of the course resulted in a normalised power of 385 watts, which far exceeding his set threshold of 360 watts. In this particular race, this athlete completed the full 90 minutes at a normalised power of 350 watts, which again illustrates the extreme demands of an XCO race. The first 15 minutes of an XCO race. This specific example was taken from an elite athlete racing in the 2016 South African National XCO Championships at Cascades MTB park. The yellow solid line represents the power he is producing at the time. The yellow dotted line represent his functional power threshold. The course profile (altitude) is represented by grey shading. The pink line is a representation of his normalised power at that specific time point. Skills will pay the bills XCO tracks are becoming increasingly technical and this places a high premium on the skill level of XCO racers. Uphill climbing ability will be largely determined by the physiological characteristics mentioned above, while descending requires less propulsive work and places a great influence on rider skill. Riders who are able successfully negotiate technical single track descents without additional pedalling, should recover faster than their less skilled competitors. The improved recovery will allow riders to produce more power on subsequent sections of the lap. All cyclists, but XCO riders in particular, should dedicate time to their training for skill development. Mariske Strauss follows Cherie Redecker into a rock garden during practice ahead of the 2016 SA National MTB XCO Champs in Pietermaritzburg. In addition to the ability to negotiated technical single track, recognising the most appropriate line is also an important skill to master. Decision-making is fast becoming a popular area in sports science. Previewing a track with a more experienced rider who can assist riders with correct and timely line choice. Sometimes it is about the bike The variety of XCO tracks in the National and World Cup XCO circuits, means that one bike may not be appropriate for all courses. Tracks that have a large amount of climbing may be best suited for a hardtail, where improved climbing efficiency may outweigh the benefits gained while descending on a full suspension bike. The more technical courses may best suit a full-suspension bike and there is definitely an increase in technical tracks in modern day races. Suspension systems on mountain bikes are designed to reduce the vibrations experienced by riders while they navigate technical single track descents. Excessive vibrations will have a negative impact on performance, but increasing the ‘cost’ of the exercise. Apart from propelling the rider and their bicycles, the rider’s muscles will have to stabilise the rider and work against the vibrations. Suspension systems that best reduce these vibrations can add a performance benefit. Conclusion In summary, XCO performance will be determined by a host of factors including; an athlete’s aerobic capacity, their ability to repeatedly produce high power outputs, their skill level and to some extent their equipment. The first race of the National XCO Cup series takes place this Saturday. It promises to be an exciting event, with the potential for one or two of the top international racers taking part. If you are in the Western Cape, pop round and watch South Africa’s best battle it out with some of the World’s top XCO racers. About the author: Science to SportScience to Sport bridges the gap between scientific research and sports men and women in the field.Utilising scientific tools and experience gained through research and practical involvement at the highest professional and scientific level, the experts at science to sport are able to provide athletes with scientifically validated methods and products which they can use to their advantage during training and competition. Get your questions answered by the Science to Sport team Ask any cycling training, racing or nutrition related questions to be answered in the Q&A with the Coaches podcast. Please submit your questions here.
  6. The team at Science2Sport which includes leading sports scientists, Dr Jeroen Swart, Dr Mike Posthumus, John Wakefield, and Benoit Capostagno, will be addressing the answers to your cycling related queries. The discussion will be led by local mountain bike pioneer Steve Bowman. Previous articles written by the Science2Sport team for Bike Hub: Who needs a coach anyway? by John Wakefield and Dr Mike Posthumus. A scientific guide to race day nutrition by Dr Jeroen Swart and Ben Capostagno. Ensuring training progression with power by Dr Mike Posthumus and John Wakefield. Training with a power meter: the ins and outs by Ben Capostagno and Dr Jeroen Swart. Submit your questions: Here's your chance to ask any cycling training, racing or nutrition related questions you have. Please submit your questions via the form below or leave a comment.
  7. Bike Hub and the sports scientists from Science2Sport will be doing a series of podcasts to address common cycling training related questions, and we want your input to fuel the discussion. Click here to view the article
  8. Dr Jeroen Swart and Ben Capostagno from Science to Sport look at the science behind race day nutrition. Click here to view the article
  9. Pre-race meal: Our bodies store carbohydrate in the form of glycogen in two main areas; our liver and our muscles. The liver stores approximately 100 grams of glycogen, while our muscles can store ~ 500 grams of glycogen. The rationale for eating before a race is to replenish our liver glycogen stores (which we later use during exercise). During the night before our race, the body’s blood glucose concentration is kept within normal range by releasing glucose from the liver.When we eat, we produce insulin in response to the carbohydrates in our diet. Insulin moves glucose into all of our tissues. However, when we exercise, GLUT 4, a transporter protein is incorporated into the surface of muscle cells and allows our muscle tissue to take up glucose without requiring the normal insulin concentrations. Exercise with high concentrations of insulin will move glucose into cells just when we actually need to fuel working muscles which can then result in a drop in blood glucose concentration leading you to feel light headed or sluggish. You should therefore eat enough to replace the liver glycogen and early enough for the insulin levels to return to normal. An easily digestible food source is ideal so that there is nothing sitting around in the stomach and small intestine when we start racing. Muesli and uncooked oats, nuts, seeds etc. can take 8-12 hours to digest and are therefore not the right meal UNLESS you are doing a stage race (in which case you are eating for the stages to come as well). Practical: Eat about 2 slices of white bread (toasted or not) with jam or honey (not peanut butter or oily stuff) and add a banana and 500ml of energy drink or recovery drink. You can also eat a bowl of pasta, but without too much meat (which will slow down digestion). You should ideally finish eating approximately 1.5 – 2 hours before the race. Anxiety about the race may cause prolonged gastric emptying. If this is the case, reduce the amount you are eating and start to eat earlier. One Hour before the race: You should not eat again until you have started your warm-up. This should be about 45 minutes before the race. Once you are on the bike, then it is safe to start eating and drinking again as your insulin levels will stay low in response to the exercise. That said, one study could not demonstrate any detrimental effect to eating shortly before commencing exercise.Consuming some carbohydrate shortly before the start will result in the absorption and delivery of maximal rates of exogenous carbohydrate (external sources of energy) from the start of the race, otherwise you are having to use your liver and muscle glycogen stores (endogenous sources) to fuel exercise and this will only last for approximately 90 minutes of strenuous exercise before you deplete liver glycogen stores, resulting in premature fatigue. The practical: Drink about 300-400mls of energy drink and eat 1 energy gel in the 30 minutes before the start. During the race Carbohydrates Carbohydrates are substances composed of the basic building blocks of sugars - glucose (dextrose), fructose and lactose. These are called monosacharides.By combining these three monosacharides you can build the first three disacharides (two sugars): glucose + glucose = maltose glucose + fructose = sucrose (table sugar) glucose + lactose = galactose (found in milk products) By adding any more monosacharides you get complex carbohydrates like maltodextrin. The longer the chain, the lower the glycaemic index (longer digestion and absorption time). Short chains of glucose molecules are known as maltodextrins. They can be as short as three glucose molecules or many more. How does this all have any relevance? Monosacharides and disacharides are very easy to absorb (monosacharides do not need to be digested and get absorbed by the stomach and first part of the gut (duodenum). Disacharides are digested by saliva and secretions from the stomach and are therefore also digested rapidly.The problem with monosacharides and disacharides are that they are very sweet. Monosacharides such as fructose and glucose being the sweetest. This can make solutions with high concentrations unpalatable, especially during hot conditions. They also have very high osmolality (high molecule to water ratio). This delays the emptying of the stomach contents and absorption. High osmolality can also cause nausea and stomach upsets. Maltodextrins are short chains of glucose molecules that are easy to digest and therefore available almost as rapidly as mono or disacharides. Despite being composed of sugars, they are not sweet. They are also less osmotically active (each chain acts as a single molecule despite being composed of a long chain of sugars). This results in a more rapid emptying of the stomach contents and also makes them less likely to cause stomach upsets. The rapid stomach emptying means that they often deliver glucose more rapidly than solutions containing monosacharides alone, despite the fact that they need to be digested into monosacharides before being absorbed. Now for the most complex part: Fructose is a monosacharide that cannot be used by muscle (glucose is the only sugar that can be absorbed by muscle cells). To be of any use it first has to be delivered to the liver where it is converted to glucose in a process called gluconeogenesis. The glucose is then transported to the muscle where it is used. However, fructose is transported across the gut wall through it’s own transporter (GLUT-5) while the other monosacharides compete for limited transporters (S-GLUT-1). Ingestion of a mix of glucose and fructose can increase the rate of carbohydrate absorption by 50% in comparison to drinking sugars containing only glucose or galactose or a mix of these two. Getting the right mix is quite a complex exercise. The first factor is the rate at which the stomach delivers any ingested substance to the small intestine for absorption. At low carbohydrate concentrations (3g/100ml or 3%) gastric emptying and fluid absorption are the greatest but as the carbohydrate content increases, the gastric emptying rate gets progressively lower. Although the emptying rate is slower with higher carbohydrate concentrations, the increased carbohydrate concentration will deliver more carbohydrate to the small intestine. This reaches a peak at about 8-10% solutions (8-10g of carbohydrate per 100ml), which is the concentration of most commercial energy drinks. Fluid absorption and gastric emptying also peak at about 500ml of fluid per hour. Any more than that and the remainder will just pool in the gut, weighing you down and making you nauseous. Interestingly, Coca-Cola is approximately 8% carbohydrate. However, most of the carbohydrates in Coke are in the form of glucose and sucrose (a mixture of glucose and fructose) which makes it sticky and sweet compared to commercial drinks. However, if there is nothing else available, Coke is a good substitute. How much carbohydrate you need depends on the exercise duration. During shorter races such as time trials there is still a benefit to ingesting carbohydrate as there are receptors in the mouth that sense carbohydrate, reducing perceived exertion and improving performance. The longer the duration of the race, the greater the rate of carbohydrate ingestion should be. For races longer than 2 hours you should aim to ingest 60-90g per hour. Only exceed 60g per hour if the mix contains approximately 1/3 fructose as you will otherwise be unable to absorb all the carbohydrate, leading to gastro-intestinal distress. Protein Finally, the addition of approximately 10-15% protein to beverages improves performance in subsequent exercise (so only useful in stage races or during hard training weeks) and also reduces post exercise muscle damage. The practical: Shorter races:Drink 250-500mls per hour of a commercial energy drink. If it is hot and you feel like drinking more, then take up to 600mls per hour or otherwise drink a little water. Do not drink too much as it cannot be absorbed and will just weigh you down. Rather throw water over your head, back and legs to cool you down. Longer races: Drink 500mls of commercial energy drink. Preferably a mix containing 2/3 maltodextrin and 1/3 fructose. This will deliver up to 50g of carbohydrate per hour. To increase this to the maximum of 90g per hour, consume energy gels or energy bars to make up the difference. If you start to feel hungry, eat an energy bar or some other easily digestible but more solid form of food. After racing and training After exercise, the enzyme responsible for restoring carbohydrate stores, glycogen synthase, is very active in the first hour. Ingesting carbohydrates (1g/kg body weight) soon after exercise is therefore far more important to the recovery process than ingesting protein.NB! If you wait too long before you take your recovery drink, then glycogen synthase will not be as active. As a result, some of the carbohydrates that you eat will be absorbed by fatty tissue and converted to fats. Your muscle glycogen stores will also not be restored optimally. You will then start the next training session or stage with lower glycogen stores than optimal. ALWAYS take your recovery drink immediately after finishing a session. If you want to lose weight, then avoid eating later on, but not in the immediate post ride period. Some studies have shown that caffeine accelerates glycogen synthesis after exercise. In one study, the subjects who were given a LOT of caffeine with the energy drink after exercise had 50% higher glycogen stores the following day. However, caffeine can prevent you from sleeping and recovering so experiment with lower doses first. Ingesting protein immediately after exercise (0.3g / kg body weight) can turn off or reduce the catabolic process, sparing muscle mass and connective tissue. This has led to manufacturing companies promoting the use of protein recovery drinks, sometimes containing only protein and no other macronutrients. The practical: Drink 400-600mls of chocolate milk or a commercial recovery drink mixed as indicated in the first 45min after a training session.Consume 200mg of caffeine with the recovery drink if it is a stage race or if you have done a hard session. About the author: Science to SportScience to Sport bridges the gap between scientific research and sports men and women in the field.Utilising scientific tools and experience gained through research and practical involvement at the highest professional and scientific level, the experts at science to sport are able to provide athletes with scientifically validated methods and products which they can use to their advantage during training and competition.
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