Sunday, December 22, 2013

Compression Garments: Moving Into Athletics

By: John Hobbs, MS. Source Endurance Senior Consultant

                Previously, we discussed the mechanism by which compression garments aid people from a healthcare perspective as well as how their mechanism of action may not work in athletes.   However, as often seen in science and medicine, tools can be employed in ways not originally intended with great benefit. This is often due to some other mechanism of action.  So, appropriately, the data assessing the actual efficacy of the tool is important.  As a result, we review several recent studies regarding the use of compression garments as training and recovery tools.
                Very little evidence can be found in recent literature supporting the use of compression stockings during or after exercise.  Studies vary from compari
ng explosive type movements to submaximal endurance activity.  For instance, Dufield and Portlus (2007) had cricket players wear compression garments with sprinting and throwing exercise.  No benefit was seen in a second round of testing in sprint, throwing and submaximal exercise performance.  This has been confirmed when looking at training with repeated bouts of high intensity activity (Duffield et al. 2008; Pruscino, Halson, & Hargreaves 2013).  Measuring common physiological variables, researchers have shown a lack of benefit when comparing VO2max and blood lactate levels when the garments are worn during exercise.  Further, there was no difference in performance in well trained athletes when comparing compression stockings, socks, and whole body garments (Sperlich et al. 2010).
                Commonly, as coaches we emphasize the principal of specificity in training.  This is the idea that training has to be tailored to the sport and specific to its demands.  Scientific literature also falls under this principal when evaluating variables.  And as such, research specific to endurance performance has been done to evaluate the effectiveness of compression garments.  Ali, Cane, and Snow (2010) found that 10K run performance was not affected when compression garments were worn during the event. More specific to cycling, no benefit was seen during time trial performance.  Additionally, a positive effect under the theory of improved circulation was not seen in regards to lactate threshold, VO2, heart rate, and gas exchange at the working muscle (Scanlan, Dascombe, Reaburn, & Osborne 2008).  And while not performed with endurance sports, the work of Montgomery et al. (2008) evaluated the efficacy of the garments under three day tournament conditions with basketball players.  This would be similar to a stage race or a weekend with racing on consecutive days.  Again, a benefit with compression garments as a recovery modality was not seen.  This is especially true when compared to cold water therapy, which, in itself has its own strengths and weaknesses.

                With the bulk of the data showing a lack of support for the use of compression garments, it is important to note that there have been studies showing possible benefits.  Several of these studies, their applicability to competition, as well as issues with the designs and finding will be evaluated in the next posting.

Tuesday, November 12, 2013

Compression Garments, Part I: Before they were used for sport

By John Hobbs, MS. Senior Consultant

                Working in the complimentary fields of medicine and exercise physiology can provide insight in to new ideas and products.   It can also aid in teasing out how the theories behind various practices are developed.  An example of this is the use of compression garments to aid recovery and increase performance.  While increased recovery or enhance performance, regardless of the mechanism of action, is beneficial, a review of literature reveals little data supporting the benefit of compression garments in athletes.  Over the next several postings, the efficacy of compression stocking use in athletes will be evaluated.
                Compression garments are not new devices.  Their use in medicine has been wide spread for a number of years.  Forms vary from tight stockings covering from the calf and thigh to pneumatic devices that contract and release at programmed intervals.  The most common use is to prevent clots from forming in individuals with circulation issues.  Essentially, a pooling of blood can occur in the limbs called venostasis.  This pooling is a prime environment for small clots to form as the blood sits in place.  When an event occurs that allows the pooled blood to be pushed back to the heart, these clots can then cause strokes, pulmonary embolisms, and heart attacks.  This is the same mechanism that prompted walking and moving around in an airplane on long flights.  By compressing the limbs with appropriate garments, venous return can then be improved and therefore significantly reduce stroke and heart attack risk non-invasively.

                A key factor in this, however, is the role of an individual’s mobility.  The mechanism by which blood returns to the heart is called the skeletal muscle pump.  As a muscle contracts, the veins are compressed causing blood to be pushed under pressure.  It then moves towards the heart due to a series of valves in the vasculature.  These essentially make the veins one-way as they shut if blood tries to go the wrong way.  The valves are similar to airport security-- once you pass it, you can’t go backwards, but instead, have to circulate all the bay back around.
                Compression garments are not a standard issue item when a patient enters a hospital or other health care facility.  Rather, they are used in patients with severely impaired mobility.  This can include degenerative diseases, stroke, or simply being too weak to move.  Essentially, these individuals no longer have an effective skeletal muscle pump.  But, if or when mobility returns, the use of the garments is discontinued.  This can include a patient simply being able to walk to the bathroom or self-propel using their legs in a wheelchair.  I’ve even seen cases where physicians made a deal with patients that if they walked to the nursing station once every two hours they are awake, the order for the garments would be removed.  The key factor in this is the small amount of mobility required to negate the need for the garments. 

                Contrast this with the athlete population.  The skeletal muscle pump is used throughout exercise.  Then, after a workout, these individuals are able to move around normally, typically without any form of venous insufficiency.  With these facts, it appears that the method of action used in ill patients would not be applicable in healthy athletes.  However, since strenuous exercise may alter some bodily functions as well as the fact that a secondary mechanism of action may exist, it is still important to assess the data to see if benefits are seen as we will do in future postings.

Tuesday, October 8, 2013

Psychological skills, coaching, and performance of cyclo-cross athletes

By: Grant Harrison, MS; Senior Consultant

Cyclo-cross is one of the most unique cycling disciplines there are. It could be muddy, snowy, sandy, hilly, rocky, and potentially all within the same race. Also common is the need to traverse parts of the course on foot, bike in hand. The overall look, feel, and ambiance of a cross race seem to leave the racers and spectators alike, thinking there must be something more to this than just being in great shape. Like many races before, my first cross race was no different when I truthfully stated, “That was the hardest thing I have ever done”.  Given the unique demands of cross, I wanted to know more about what it takes to excel at cross. Specifically, what makes a cyclo-cross athlete successful and how do psychological skills, experience, and coaching influence performance. These questions led me to conduct a study that compared the psychological skills, elements of experience, and coaching, to the performance of athletes competing in the 2013 cyclo-cross national championships.

As psychological skills are not a physiological or performance measure, they are much harder to quantify. However, there is no doubt that psychological skills for better or worse, contribute to performance. Mental preparation, anxiety coping, confidence, concentration, motivation, goal setting, and relaxation are all psychological skills we may have or use. Previously, no research had investigated the comparison of psychological skills of cyclo-cross athletes or had examined the relationship between psychological skills, performance, and coaching of cyclo-cross athletes.
Photo: Grant Harrison

In gauging psychological skills, a brief survey known as the Athletic Coping Skills Inventory-28 (ASCI-28) was used to measure psychological skills on the sub-scales of coachability, concentration, confidence & motivation, coping with adversity, freedom from worry, goal setting & mental preparation, and peaking under pressure. In this study, coaching was measured by whether or not an athlete currently had a coach or had a coach in the past, and then by how long they have worked with a coach. Many other variables such as frequency of communication with a coach, and commitment to the discipline of cyclo-cross were also asked of each participant. These psychological skills, experience in the sport, and involvement with coaching were all compared along with each participating athletes performance in their highest priority race.

One of the many ways that coaches may help athletes is in helping athletes set appropriate goals and objectives. A preliminary analysis of the results found a correlation between being coached and goal-setting. Additionally, coached and goal-setting were both positive predictors of performance. So not only did coaching help athletes set more goals, but they performed better! Correlated with goal-setting, were confidence & motivation and concentration, however other sub-scales did not show to be correlated with goal-setting.  Although coaching demonstrated to be a positive predictor of goal-setting, coaching was negatively associated with freedom from worry. In other words, athletes who were coached reported to set more goals, but also worried more about their performance. Consequently the same athletes who had coaches, and performed better, also reported a higher commitment to the sport, which seems a likely explanation for the higher levels of worry. Among the other psychological sub-scales, surprisingly no other variables were significant predictors of performance.  Among other variables measured performance was predicted by years experience as expected, and of the coached athletes, frequency of communication with a coach also predicted performance.

So what do these findings tell us in terms of psychology? First of all, working with a coach should help athletes more clearly define their goals as supported by the study. Beyond goal-setting, there is an apparent need for coaches to strengthen athletes’ mental skills in addition to physical ability. This might involve role-playing, use of imagery, or other techniques that influence how an athlete responds to certain situations. Clearly, being race ready and seeing results will be motivating and help instill confidence, but it may be just as important to strengthen the mental skills that help an athlete overcome adversity or defeat.  As supported by this study, more successful athletes are in continual communication with a coach. In this case the word “communication” may be interchangeable with “reinforcement”.  With every experience that an athlete goes through, there is an opportunity to be influenced by its’ outcome, as coaching may be an excellent way to help an athlete identify what should be taken out of each experience. Ultimately, the findings of the study support that the highest performers in cyclo-cross, have experience and seem to possess stronger psychological skills that may be influenced by the presence of a coach.

Editor note: This article is written as a reference to Mr. Harrison's master's thesis.  His thesis will be posted to the Source Endurance website soon so stay tuned. 

Wednesday, October 2, 2013

Heat Consequences of Aero Road Helmets

By: Zack Allison, Senior Consultant

While sitting on the couch between races at Gateway Cup, the Think Finance p/b Trek Stores Cycling Team and two Source Endurance coaches jumped into  a discussion on aero road helmets. The weather for this particular race weekend in Saint Louis was an average of around 100F at each of the races. The major question was if the aerodynamic benefit of aero helmets outweighs the power loss from overheating on a hot day.  We decided to try and find studies on the subject of whether aero helmets cause power loss due to overheating. We knew it would be a task to find applicable studies on overheating from a specific type of helmet but we did our best.

Good Aero Position
Bad Aero Position
First we looked at the aerodynamic benefit of aero helmets. The study Benchmark of Aerodynamic Cycling Helmets Using a Refined Wind Tunnel Test Protocol for Helmet Drag Research by Stephanie Sidelko of MIT , compared 10 different aero helmets to a standard road helmet on aerodynamic efficiency. Using different angles of yaw, or different directions of wind, they set out to determine just how aerodynamic these helmets were. At the MIT Wright Brother Wind Tunnel, scientists measured the drag of these 10 aero helmets at 30mph. Another variable added to the study, increasing its relevance, is different angles of how helmets sit on a rider’s head. We all have seen an aero helmet on a rider; a good helmet position has the tip of the helmet touching or very close to the rider’s back and a bad position has the rider’s helmet pointing straight up in the air. The scientists took this into account by moving the helmet on the mannequin’s head to mimic these positions and also comparing these values to the normal road helmet.

The fact that some riders put their heads down and many riders have bad aero helmet positions is a big reason why aero helmets are losing their tails. Many of the newest designs in aero helmets have a chopped tail or no tail at all. Road aero helmets are, in many cases, more aerodynamic than an aero helmet with a bad fit.

The results of the study showed that every aero helmet, in position 1 and 2 on the rider’s head as represented in bar graph form in “figure 6 below”  was more aero dynamic than a standard road helmet. At position 3 on the rider’s head, which is basically with the tail of the helmet pointed straight up, most aero helmets were still faster than a standard road helmet but by less of a margin. It is difficult to transfer these drag numbers into wattages as every rider has different wattage numbers at threshold and different positions. An aero helmet is up to 8% reduction in drag at 30mph so for a rider with a threshold of 425 watts, this comes out to around 30 watts of power under these specific conditions according to this study. Each helmet tested in this study had different drag characteristics based on its shape indicating that, as the aero helmet position changes, there is more drag associated with aero helmets with larger tails. The take home point, however, is that in the correct position, an aero helmet is much more efficient than a standard road helmet.    

"Figure 6"
Now that we know aero helmets are faster than standard road helmets we can try to find out if these helmets are creating an amount of extra heat that is hindering our performance.  For that we have to find a new study. Looking for information on heat dissipation of standard road helmets vs. aero road helmets we found the study AERODYNAMIC EFFICIENCY AND THERMAL COMFORT OF BICYCLE HELMETS to be the most relevant.  “Firoz Alam, Simon Watkins, Aliakbar Akbarzadeh and Aleksandar Subic” This study had nearly the same protocol as the aerodynamic study mentioned above except that this study was conducted in a wind tunnel, used various road helmets and put a heating element on the mannequin’s head. The heating element was heated to 140 degrees Fahrenheit and then, while the wind in the tunnel was blowing at controlled speeds, the sensors on the heating element would read temperatures
telling us which helmet had the best ventilation. This study also compared aerodynamic factors of the helmets it tested using different pitches of air. The pitches of air take into account the 2 things: 1. different helmet positions on the rider’s head, as we have seen in the previous study and 2. the relevance of vent placement on the helmet itself, which we will see later is key in keeping a rider cool with an aero helmet.

The results of this study on how heat is dissipated in different levels of road helmets showed that the more aerodynamic the helmet, the less heat was dissipated. In other words ventilation comes at the price of heat dissipation. The helmets that were most aero in the study were actually multi-use helmets that looked very close to the Air Attack by Giro. One of the helmets with vents un-taped is seen on the right. The vents were taped in the study.

 The results of the study showed that the helmets with the worst aerodynamic performance were the most ventilated and looked close to modern helmets of today’s professional peloton. We don’t know the temperature of the wind tunnel air and the 140 degrees of heat that they started with in the helmet is not really close to temperatures in your helmet while on the starting line of a hot Midwest Criterium but we can use it to see just how much heat we are retaining in our aero road helmets compared to our super light, highly ventilated helmets. The most ventilated helmet at a 0 yaw and 0 degree pitch angle of air, or a straight head wind, went from 140 degrees to 75 degrees. This is a 65 degree difference. The most aero helmet with vents taped is significantly more aero than the most ventilated helmet. The temperature inside this helmet dropped from 140 to 124, only a 16 degree drop in temperature in the wind tunnel.

This tells us that the vents work on helmets to cool your head and that there IS in fact a very real danger of overheating from use of an aero road helmet in hot races. There are other factors in the study that we have to take into account before we try to “estimate” at temperature at which an aero road helmet starts to hinder performance.

   What was interesting is that, using different pitches of air and focusing air on specific vents, the study could tell us what types of vents worked on the helmets they tested and what vents did very little in dissipating heat. You can have a helmet with huge vents that does not dissipate heat very well and you can have a helmet with very small, aero, strategically placed vents that dissipate heat very efficiently. The vents on the Air attack and Specialized Evade aero road helmets, as seen here, seem to be small but could be more effective than some larger vents. It’s important to remember that the temperatures used in the latter study are not skin temperature measurements;  the experiment used a heating element and measured drops in heat to see which of the tested helmets had the best ventilation. Also the vents on the most aero helmet in the study were taped.  I’ve never seen anyone tape the vents on a Giro Air Attack but that could drastically change the ventilation and aerodynamic numbers.

Specialized Evade, notice innovative vents and placement
Another major point of the study AERODYNAMIC EFFICIENCY AND THERMAL COMFORT OF BICYCLE HELMETS is that placements of vents are crucial to how they work. The study used different pitches and angles of air to see effects on temperature. Some helmets performed better at different pitches of air, showing us that vents work in different ways. If a vent works best to dissipate heat at 90 degrees of pitch, or straight down, then it’s likely not very useful as you will never really get that air flow unless you are riding with your head all the way down (not recommended). Some helmets have vents that work best at a level air flow. If an aero helmet can utilize smaller vents to reduce drag by making those vents in ideal places and sizes for ventilation then it will be a superior helmet.

These studies work on a fundamental level for us. We Can compare the findings in these studies to helmets currently on the market, how aero dynamic they are, and how well they dissipate heat. The actual temperature changes would be per individual and per helmet and would vary depending on air density, humidity, wind speed, and direction, color of the helmet, and acclimatization of the rider. Fundamentally what we can take away from this research is that aero road helmets are significantly more aerodynamic than standard road helmets. They WILL save you watts. Aero helmets are also significantly warmer than heavily ventilated road helmets. If your event is already dependent on keeping cool then a performance enhancement made by wearing an aero road helmet will have heat consequences. The Source Endurance team gave a rough estimation of 75-90F degrees for when we would trade an aero road helmet for a more ventilated one. Again this would depend on speed of the event and a dozen other factors on race day.  In most situations, where your event is not blistering hot, an aero road helmet will be more efficient. 

Tuesday, January 1, 2013

Offseason Training, Don't Waste Your Base (2 of 2)

By: John Hobbs, MEd. Senior Consultant

  Once it was observed that many of the benefits seen with longer and easier training sessions were also seen with shorter and harder workouts, the next step was to identify which changes do and do not occur among the two training modalities.  By analyzing training adaptations at different intensities in individuals of various fitness, multiple changes occur at the cellular and enzymatic level when any of the variables are altered.  So while aerobic gains of types do occur at very high intensities that also occur at lower intensities, as various enzymes and cells are pushed in different ways at the various workloads, the changes are not the same across the board.  Changes in fiber type of muscles, enzyme activity, expression of various proteins and a whole slew of activities are dependent on intensity, volume, and fitness of the individual.     As a result, hopping on the trainer and cranking out maximal efforts does not provide the same benefits as lower intensity efforts of longer duration.  Additionally, the negative health and training ramifications as well as stagnation that occur with long periods of intense training make the combination of early and late season intensity impractical and counterproductive to an athlete's form.
Which periodization model is best for you?
            The individual athlete is a key in the assessment of the changes.  A fit athlete may only see some of the changes observed in an individual of lower fitness level, and even then, the gains may be smaller.  Additionally the benefits seen by two individuals of similar performance levels may not be the same due to the fact that the one athlete has already exploited the changes in previous training (ie enzyme x increase significantly in one athlete but not the other).

What about this model? 
Does this one work? 
So many models!
At this point is seems that we've just talked ourselves in a corner by arguing the typical base training paradigm is not a good way to go in the off season and  neither are short hard rides.  In the end, the training has to fit the needs of the rider.  By moderately increasing exercise intensity to the tempo and steady state type work, we can compensate for the lack of volume that average athletes have.  This allows for an overload to take place, but still allowing for adaptations to occur that may not be seen at higher intensities.  The question still stands of how to address the demands of a 3+ hour race.  The overload provided during a standard training week with three to four hour ride in the typical base training zone on the weekend does not provide most athletes with sufficient overload of various physiological systems to provide a training benefit.  But by including intervals during the week, the overall training stress is increased which can, in-turn lead to stimulation of various adaptations.  And while it may seem like we are contradicting ourselves, training volume can increase even as intensity increases with training.  While following the periodization format exactly as the theory dictates would not allow for this, it can be done in proper increments as dictated by the overall stress of the current training.  This is where the coach and physiologist is able to bridge the gap between science and practical implication of training.  As coaches we realize that long rides are not available all weekends to every athlete. As physiologists, we have the expertise to adjust the training to allow for workouts to address the needs of longer events.  Athletes may see the duration of their long rides increase in periods of relatively high training intensity.  The increases may be small and not occur every week, but it allows for appropriate training for specific events.
It is possible none of these work for YOU.
Often times, SE consultants don't stick to any of these models. 
This one? Often times SE must generate a custom model.  
            As touched on earlier, the main variable in designing an off-season training plan is the athlete.  A blanket statement that high intensity workouts do not belong in the off-season would be inappropriate at the least.  These workouts may, in fact, be beneficial to a population of athletes under proper circumstances.
            While various physiological principals were covered and stances taken based on data, it is noted that no studies or peer-reviewed literature was cited, as is contrary to typical articles.  The frustration felt by those hoping to reference sources, critique the statements made, and those who are just fellow science geeks is understood.  Rather than explain a scientific principal, the goal of this article is to illustrate the madness behind the coaches’ methods and provide background information on the structure of training during this period.