Thursday, March 6, 2014 Balance, Fatigue and Carbohydrates

Over the past few years, coaches and researchers have been asking how balance affects different athletes. For sports such as gymnastics, the need for balance is obvious. In other sports like soccer, research shows that the ability to maintain balance also influences performance during cutting and changing directions. We also know that balance plays an important role in injury risk. Balance results as a response to various sensory inputs – both visual and mechanical. The central nervous system (CNS) processes this information then activates the appropriate muscles to reposition the body and/or to stabilize a joint. When the CNS cannot respond appropriately, players may fall or they may sprain or tear ligaments. Thus, a loss of balance is a key to players playing well and staying healthy. Two recent studies examined the relationship between fatigue and balance in young athletes. The first shows the extent to which fatigue disrupts balance while the second suggests that carbohydrates may be a solution to maintaining balance during a match.

In the first study, the researchers asked the question, how much does fatigue affects balance in young soccer players? Earlier studies looked at older, adult players but this is the first to focus on youth. The players were 14-15 year olds selected from competitive teams. Balance was measured by having the players stand on a pressure platform using one and two-legged stances. The pressure platform then measured “postural sway” – the degree and speed in which the athlete’s center of gravity swayed forward, backward, left and right. The greater the sway, the less balance exhibited by the player. The players did this before and after undergoing intense exercise designed to induce fatigue. For the fatigue protocol, the players were asked to go through several minutes of a moderate-intensity warm-up, and then perform six, 2 x 15 meter shuttle runs, separated by 20 seconds.

After exercise, the players’ balance was markedly disrupted. Regardless of which leg they stood on, their body swayed much more after fatigue than before. This was true for the amount of sway and how quickly they swayed to the front, back and side. In fact, the loss of balance was directly related to the degree of fatigue experienced – greater fatigue, more sway and less balance.

Similar to older, adult players, fatigue greatly affects balance in young soccer players. The authors point out that 14-15 year olds are still developing their proprioception and balance control systems. In these players, “neuromuscular immaturity”, weakness, fitness and training may also influence fatigue’s ability to disrupt balance. They go on to emphasize the role training plays in developing balance and avoiding injury in this age group.

The second study looked at young gymnasts (11-14 years old) and balance beam performance. The objective here was to determine how fatigue and a carbohydrate supplement affected the number of falls. One group of athletes underwent a warm-up followed by five sets of beam exercises. A second group participated in the warm-up plus 20 minutes of intense gymnastics training (designed to induce fatigue) before performing the five-set beam exercise. Shortly the beam routines, both groups of gymnasts were given either flavored water or a carbohydrate beverage.

As in the soccer study, fatigue affected balance by increasing the number of balance beam falls from 3.3 to 5.4 (63%). Interestingly, the carbohydrate supplement reduced falls regardless of the athlete’s level of fatigue. After intense exercise, falls were reduced to an average of 2.3. Without exercise, they were reduced to 1.9. Thus, a carbohydrate beverage can improve balance and balance beam performance in both fatigued and non-fatigued gymnasts.

What is interesting about this study is that the gymnasts did not experience a decline in blood glucose (hypoglycemia) following the intense training bout. Hypoglycemia often accompanies fatigue and can have negative effects on performance where effort, motivation or motor skill is involved. In fact, we often attribute the positive effects of carbohydrates on either prevention or reversal of hypoglycemia. In this study, hypoglycemia did not occur. Nevertheless, the researchers attributed the reduction in falls with carbohydrates to improved focus and attention.

Previously on the SSO, we’ve discussed an interesting effect of carbohydrates on athletic performance. As it turns out, players may not need to actually ingest carbohydrate drinks to gain an advantage. A “rinse and spit” method can also improve performance. That is, swishing the beverage in mouth without actually ingesting it has a psychological effect on performance by improving effort and skill. It seems that there is a link between the mouth and the brain that is somehow stimulated by carbohydrates. In fact, brain imaging studies show that just the presence of carbohydrates in the mouth activates regions of the brain involved in reward and the regulation of motor activity. This may be what affected the gymnasts’ performances. Carbohydrates in the mouth stimulated the brain and improved focus, attention and/or motor skill leading to improved balance and fewer falls.

Back to the soccer players and their balance problems with fatigue. The authors of the first study point out that neuromuscular training programs that include balance, strengthening and plyometric exercises are the best option to increase balance and reduce injury risk (as well as improve performance). This is especially true in young athletes. However, if carbohydrate beverages can improve balance and reduce falls in fatigued gymnasts, one can assume that they would do the same in fatigued soccer players. Thus, carbohydrate drinks given before and during training or matches, may be an additional tool for preventing injuries. By affecting the brain, carbohydrates may restore balance, prevent unwanted joint movements and reduce the risk of sprains, ligament tears and falls.

We’ve known for years that carbohydrate beverages provide fuel and hydration, both of which affect performance. This added benefit, linking the mouth to the central nervous system may aid in maintaining balance. To be truthful, this idea hasn’t been studied in detail. However, it is food (or drink) for thought.

References

Massimilano P, Ibba G, Attene G (2014) Fatigue-induced balance impairment in young soccer players. Journal of Athletic Training, in press, doi: http://dx.doi.org/10.4085/1062-6050-49.2.12

Batatinha HAP, et al. (2013) Carbohydrate use and reduction in number of balance beam falls: implications for mental and physical fatigue. Journal of the International Society of Sports Nutrition, 10:32.

Chambers ES, Bridge MW, Jones DA (2009) Carbohydrate sensing in the human mouth: effects of exercise performance and brain activity. Journal of Physiology, 587: 1779-1994.
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Labels: Current Research, Injuries, Nutrition

NSCAA Convention Recap

Thanks to everyone who attended my session on the recovery diet. It was a full house with some very good questions from the audience and from the Twitter feed. I want to thank the NSCAA for inviting me and giving me a change to “bridge the gap” between science and performance.

Gatherings like these are places where you meet new people and learn new things. If you have noticed, a major topic that is being discussed in most such formal and non-formal events is the growth of crypto currencies and the trend of trading with bots. Bot trading might sound something like a concept straight out of a science fiction movie. But it became a reality several months ago. There have been so many advancements that the bots designed to act as the trader can learn and evolve. These are self-learning bots that can observe their decisions compare them with the market results and the real time market data and then improve each of the future decisions. So the strategy that is fed into the bot would improve over time. The trading bot might also learn to compare and pick the best features in order to take the decisions quickly and accurately. Such advanced bots are the bots designed for the future. They are in fact the bots that are also the most relevant for the present trading scenario. So in a market that is filled with trading bots of different types and different customisation options the bots with self-learning abilities are the ones that stand out. These are also the ones that end up making better profits than the other similar bots in the field.

The self-learning bots would also have a competitive edge when it comes to making decisions in the fluctuating markets. Market fluctuations are prone to occur all the time. The way the trader makes use of these fluctuations is what determines the success of the trader, the profits he makes. For this the trader should be able understand the market cycles in crypto markets. If you are a first time crypto trader, my review here talks about one such trading bot that works pretty well in changing market conditions and gives some good profits for the investors.

If you weren’t able to attend, a recording of my presentation can be found HERE.

Also, the PowerPoint slides that I used can be found HERE.

Posted by Jay Williams, Ph.D.

The Advantages of High-Intensity Interval Training

Soccer is a unique sport where the average player covers up to 7 miles per games by running forward, backward, and sideways. Intermittent sprints are quite frequent, with players performing them around every 90 seconds. Players may also change directions nearly 1,000 times a match. Whether it is walking, jogging, or sprinting, some type of movement is always occurring. Given that the length and intensity of movements are somewhat random, it is very difficult to make a fitness-training program that adequately mimics the physical demands that are required of a soccer match. Traditional methods of fitness training such as going on a long distance running do not mimic the physical demands of a match, and thus may not be the most effective training method for soccer players. A more progressive training regime that has been labeled as high-intensity interval training (HIIT) has become popular amongst athletes in order to increase their fitness capacity.

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This article was written by Jeremy Williams

Many sports scientists have classified it as a “hybrid” sport, in reference to it requiring training of both the aerobic and anaerobic energy systems. Maximal oxygen consumption or VO2max is generally considered the best indicator of an athlete’s aerobic capacity and his/her ability perform exercise for long periods of time (cardiorespiratory endurance). Athletes that are considered “elite”, typically have a higher VO2max than those who are less competitive. Professional male players have VO2max values above 60 ml O2/kg.min, whereas female college players average in the mid 50’s. Because of the aerobic demands of the sport, a high VO2max gives a soccer player a distinct fitness advantage allow for a better performance on the field, especially during the later stages of the match.

HIIT is a program whereby an individual performs several intense, near maximal bursts of anaerobic activity lasting between 30 seconds and four minutes. These bouts are separated by fixed periods of less-intense activity, which might include light jogging, walking, or even complete rest. An example would be, an individual that runs a 150-200-meter sprint at maximal intensity, followed by a 2-minute recovery period of light jogging or walking. This is then repeated 4-6 times until the workout is completed. Does this type of training actually work? Does HIIT improve VO2max in soccer players?

Does HIIT Work?

A number of research studies have shown that HIIT increases aerobic capacity in untrained individuals. In addition, studies are emerging that show important effects on trained athletes and soccer players. They show that VO2max is increased between 6-8%. An excellent example of how HIIT can improve fitness in soccer players is a study carried out by researchers at Willamette University in Oregon. They compared HIIT and endurance running during an “off season” training period. They were interested in determining which form of training is better for improving fitness. The HIIT group performed five-30 sec maximal sprints separated by 3.5-4.5 minutes of recovery. The other group underwent 40 minutes of continuous running at 80% of their aerobic capacity. Training was conducted twice per week for 5 weeks. In both groups, VO2max increased by 4%, from 50.7 to 52.7 mL O2/kg/min. Also, performance on the Yo-Yo intermittent endurance test was equally improved.

HIIT has also been compared to other forms of soccer fitness training. For example, a recent study found that both small-sided games and HIIT improve VO2max by 7-8%. In terms of match performance, HIIT also results in players spending more time engaged in high intensity running efforts.

Research also shows that repeated sprint performance and exercise economy are improved following HIIT. Both of these changes are important for the athlete. One could argue that soccer is essentially a 90 minutes test of repeated sprint performance. Thus, HIIT offers a very sport-specific training adaptation. An increase in exercise economy means that he or she is using slightly less energy when performing the same amount of work. Some think that HIIT may improve running and sprint mechanics leading to less wasted energy. Whatever the cause, improving exercise economy could lead to important energy savings over the course of a match.

Based on these research studies, it is clear that HIIT does indeed improve VO2max in soccer players. Also, HIIT improves other aspects of performance like exercise economy and repeated sprint performance. Each of these improvements would be expected to translate to increased performance on the pitch.

How Does HIIT Work?

VO2max is determined by two key physiological variables. The first is cardiovascular performance and the heart’s ability to deliver oxygen to the muscle. Stroke volume or how much blood the heart pumps per beat is key to oxygen delivery. The second variable is the muscle’s metabolic capacity or its ability to extract oxygen from the blood and use it to produce energy. Improvements in VO2max following endurance training typically result from a 50/50 combination of cardiovascular and muscle adaptations. However, HIIT seems to increase VO2max by improving the muscle without affecting the cardiovascular system. That is, muscle metabolism is increased while stroke volume remains relatively unchanged.

Within the muscle, mitochondria (called the powerhouses of the cell) are the most affected by HIIT. These structures, located inside each muscle fiber have the machinery needed to combine oxygen with fuels like glucose, glycogen and fat to energy. Research shows that HIIT stimulates the muscle to produce more mitochondria. This means that the muscles of HIIT-trained players are better able to use oxygen than their endurance-trained competitors. HIIT also leads to increased muscle glycogen and a slower rate of glycogen use during exercise. Muscle glycogen is a critical fuel source for the player. The ability to slow glycogen depletion could pay dividends later in the match.

Thus, while HIIT and traditional endurance training both accomplish the same goals, they do so in somewhat different ways. Endurance training improves both the cardiovascular system and muscle metabolism. On the other hand, HIIT seems to cause greater improvements in muscle metabolism.

Why Might HIIT Be Better?

The fact that HIIT improves muscle metabolism has important implications for the soccer player. Soccer players generally have very high cardiovascular function. However the start-and-stop, sprint-jog-run nature of a match places a high demand on the muscle’s aerobic and anaerobic energy systems. Since HIIT relies on repeated high intensity sprints, it is very likely that both of these energy systems are stressed. Thus, a training program that and simulates the movements and energy demands encountered during a match is important for the player. HIIT training should give him or her the ability to jump, start, stop and change directions more effectively during the end of a match when fatigue starts to set in.

The second key advantage of HIIT is the time commitment. In the Willamette University study, the HIIT athletes trained 20-25 minutes per session compared to almost twice that time for the endurance group. This, HIIT can be a more economical way to improve fitness. For teams that have limited practice time on the field, this can be a huge advantage. Being able to improve fitness with a lower time investment leaves more time to work on other technical and tactical aspects of the game.

Using HIIT

Dr. Martin Gibala at McMaster University suggests that a combination of HIIT and endurance training may be best. Substituting 15-25% of the traditional training volume with HIIT or incorporating 2-3 sessions per week. Obviously this routine depends on the time of year and whether players are in-season, pre- or off-season. A greater number of HIIT sessions can be used during the off- and pre-season when the emphasis in on developing fitness. While in-season training may use HIIT once per week to maintain fitness.

The bottom line is that, research shows that HIIT is an effective and economical way to improve aerobic capacity in soccer players. In fact, the effects of HIIT on the exercising muscle and the minimal time commitment may make this mode or training preferable to traditional endurance running.

Jeremy Williams is currently a graduate student at Florida State University and assistant with the women’s soccer team.

References

Dupont G, Akakpo K, Berthoin S (2004) The effect of in-season, high-intensity interval training in soccer players. Journal of Strength and Conditioning Research, 18: 584–589.

Gibala MJ, Jones AM (2013) Physiological and performance adaptations to high-intensity interval training. Nestle Nutrition Institute Workshop Series, 76:51-60

Gibala MJ, McGee SL (2008) Metabolic adaptations to short-term high-intensity interval training: A little pain for a lot of gain? Exercise and Sports Sciences Reviews, 36:58-63.

Helgerud J, Engen LC, Wisloff U, Hoff J (2001) Aerobic endurance training improves soccer performance. Medicine and Science in Sports and Exercise, 33: 1925-1931.

Impellizzeri FM, Marcora SM, Castagna C, Reilly T, Sassi A, Iaia FM, Rampinini E (2006) Physiological and performance effects of generic versus specific aerobic training in soccer players. International Journal of Sports Medicine, 27: 483-492.

Rowan AE, Kueffner TE, Stavrianeas (2012) Short duration high-intensity interval training improves aerobic conditioning of female college soccer players. International Journal of Exercise Science, 5: 232-238.

For more info on HIIT

High-Intensity, Sprint-Interval Training and Fitness

High Intensity Training, Fitness and Training Time

Posted by Jay Williams, Ph.D. Labels: Training

Soccer Diet

Soccer Diet: The Simplest Way to Improve Your Team’s Performance
An E-Learning Course and Community

Sports Path™ and Professor Jay Williams have combined to develop, an interactive, online learning course and ongoing community. Our goal is to assist coaches with improving the diet and performance of their players. Improving player performance is at the heart of this course and community. Key features include:

Skills – to be a successful soccer player it needs to have more skills other than technically and tactically talented. A good soccer player is not only good decision maker bet they are also strong, powerful. As they make the physical component of the game so sharpening their skills with exercise and practice is very important.

Training- training every day without fail is very important for a soccer player, from goalkeeper to midfielder everyone needs a dedicated training regime. Everyday training makes the player perfect and helps them to overcome their weaknesses.  It improves the infield strengths of a player. It is not easy to play for 90 minutes at a stretch it needs the lot of exercising, jogging, running to stay in the field with full stamina.

Tactics – soccer is the game of strategies, it involves individual skills and team tactics as well. For a viewer it is a 90 minute game in which one team has to score more goals than others but to score these goals  a lot of planning and team tactics is required, it is not a game of individual  player where he can showcase his own talent but the team as a whole has to perform well to win the game.

Nutrition- food is fuel for the body so eating a balanced diet is necessary to have a sound mind and body. A soccer player should eat 22- 24 calories times as per body weight. They should eat 1- 1.5 grams proteins times according to body weight. Eat carbohydrate according to the physical activity.   See it here to know more about nutrition

Download all 15 chapters of The SCIENCE Behind Soccer Nutrition
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The SCIENCE Behind Soccer Nutrition, 2nd Edition
By: Jay H. Williams

This book stresses a set of fundamental principles, built on scientific research designed to guide you through the nutritional challenges of training and competing. The 2nd edition contains updated and new chapters, focused on helping players develop their individual nutritional strategy for maximizing performance.

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Stressed Out: Daily Hassles Can Increase Injury Risk

Be they youth or adult, many soccer players feel the stress of everyday life. Life events and how well the player copes can create worry, anxiety and mental fatigue, all of which affect concentration and effort on the field. Previous research shows that stress from major life events can also raise the risk of injury. Stress and anxiety also comes from smaller, daily events or hassles. For example, a college player finding the time to study for mid-term exams, meet a class project due date and focus on an upcoming match may experience significant daily stress. On the other hand, small victories in the classroom can lift a player’s sprits. A group of Swedish researchers focused on how these smaller, daily stressors have on injury risk. They find that that daily hassles and daily uplifts can make an athlete more or less susceptible to injury.

The researchers surveyed more than 100 Swedish elite youth players (ages 15-19 years) over the course of one year. Each week, the players were asked to complete an inventory of daily hassles and uplifts. Items such as family issues, personal relationships and daily responsibilities were recorded. Players were also asked if they considered these situations to be hassles or uplifting. During the study period, the researchers also recorded injuries sustained by each of the players.

The results showed that the occurrence of injuries was tied to both the initial daily hassle level and the change in daily hassle over the course of the year. Players who showed high initial daily hassle at the start of the study with little change in hassle level were the most likely to suffer and injury. Those with greater uplifts throughout the season suffered the fewest injuries. When the level of hassle or uplift changed, the occurrence of injury also varied. Thus, the researchers concluded that players who experience daily hassles are at greater risk of injury whereas uplifting daily events can lower risk. Further, injury risk fluctuates as daily stressors change over the course of a season.

The researchers point to several reasons why daily hassles and uplifts affect injury risk. Previous research shows that hassle can increase psychological fatigue as the player copes with daily events. Hassle is also associated with diminished cognitive function such as loss of concentration, focus and attention. On the field, both psychological and cognitive changes can have a major impact on performance. Reduced effort and poor decision-making can also place the athlete in situations where injury risk is greater. For example, a poorly timed and executed tackle due to mental fatigue and lack of proper judgement.

On the other hand, daily uplifts have an overall positive effect on performance. Positive effects include better problem solving and decision-making capabilities and less psychological fatigue. These result in greater focus and effort on the field and, most importantly, a reduced risk of injury.

Small, daily hassles can impact player performance and injury risk. Coaches who work with high school and college players should realize that daily hassles such as academic demands and social pressures could lead to day-to-day changes in the stress level of their players. This in turn, could lead to injuries.

In the movie, “Trouble With the Curve”, the Atlanta Braves baseball management was losing hope in a top prospect who was struggling to hit the ball against minor league competition. Long-time scout, Gus Lobel says that the young player was homesick (daily hassle) and just needed to see his family. After arranging a weekend visit (uplifting), the young prospect had a great weekend at the plate. This movie clip emphasizes how small changes in the emotional state of an athlete can affect performance. Being aware of daily hassles and stressful events like homesickness, congested travel schedules and pending exams can help the coach adjust training and provide a more positive environment to counter the negative hassles. Also, understanding that coping abilities vary from one athlete to another could aid the coach in dealing with individual player performance. By attending the psychological and emotional health of the player, physical health and match performance can be maintained.

Reference

Ivarsson A, Johnson U, Lindwall M, Gustafsson H, Altemyr M (2013) Psychological stress as a predictor of injury in elite junior soccer players: A latent growth curve analysis, Journal of Science and Medicine in Sport, http://dx.doi.org/10.1016/j.jsams.2013.10.242
Posted by Jay Williams, Ph.D. Labels: Current Research, Injuries, Psychology

Kudos to the Soccer Moms

By design soccer is an activity that promotes health and fitness. The amount of exercise performed at practice and the emphasis on proper diet directly affects players’ fitness and promotes a lifestyle that influences health well into adulthood. A recent study now suggests that participation in youth sports may have other, unanticipated effects that may lead to an overall healthy lifestyle. Researchers from SUNY Brockport have found that playing sports may have some influence on whether or not high school kids use their seatbelts.The design of the Bitcoin loophole software was done to exploit the profitable opportunities in Bitcoin trading. The founders Steve McKay claims to have identified a loophole in the Bitcoin network from which he has been able to generate sufficient profit for himself. After getting steady returns from this application, he decided to provide free access to this website so that people could gain equal access to financial prosperity.

The study analyzed the data found in the US National Youth Risk Behavior Survey. This survey is administered every two years to groups of 9th through 12th graders. For this study, two aspects of the survey were used. The first was a question about seatbelt use when riding in a car. The teenagers were categorized as those who always / mostly / sometimes used seatbelts and those who rarely / never used them. Second, athletic participation was determined by how many high school or club sports each kid participated in. Non-athletes did not participate in any sports, moderately involved athletes played on 1-2 teams per year and highly involved athletes played on 3 on three or more teams.

Of nearly 19,000 students surveyed, 81% reported that they used seatbelts at least some of the time. The results also showed that girls were more likely than boys to wear seatbelts as were younger teens versus older teens. The more interesting finding was that both moderately and highly involved athletes reported more seatbelt use than the non-athletes. In this study, non-athletes were 25% more likely to report that they rarely or never wear seatbelts than were the teens that played sports.

The investigators argue that the differences between athletes and non-athletes may be related to personality types and the need for teens to engage in “risky” behaviors. Sports may provide an alternative to risky behaviors such as not wearing a seatbelt. They also suggest that athletes may avoid risky behaviors out of fear that their place on the team may be jeopardized. They may fear being punished by their coach or parents, especially if the behavior results in a violation of seatbelt laws.

While the researchers may be on to something, they may have overlooked a more obvious reason for the increased seatbelt use among teenage athletes. Seatbelt use is a habit that probably gets ingrained early in life. It seems reasonable that young children who grow up wearing seatbelts will use them as teens. This is where the soccer moms step in. How many parents who drive the team carpool have said, “We’re not going anywhere until everyone buckles up”? Could it be that this insistence on seatbelt use helps kids develop a habit that lasts once they’re driving on their own? Maybe all of those trips to and from practice have the unintended benefit of promoting a healthy lifestyle practice!

Nearly everyone is aware of the importance of seatbelt use. Using a seatbelt is estimated to prevent nearly 16,000 deaths annually and as many as 350,000 injuries. Seatbelt use is perhaps the most important factors in preventing injury and death during an auto accident.

So, to all you soccer moms (and dads): keep up the good work. Pestering your kids to wear their seatbelts may be paying off!

Reference

Melnick MJ, Miller KE, Sabo DF, Barnes GM, Farrell MP (2009) Athletic participation and seatbelt omission among US high school students. Health Education and Behavior, in press, DOI 10.1177/1090198107308377.
Posted by Jay Williams, Ph.D. Labels: Current Research, Health

Is Home Advantage Really an Advantage?

In all sports, teams strive to gain home field advantage. The consensus is that playing in the home stadium, in front of the home crowd offers a distinct advantage. In the 2012 Olympics, many feel that England’s success was due in part to their athletes competing on home soil and in front of the home crowd.

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In soccer, consideration of home field advantage is so great that away goals are given more weight in two-leg fixtures. Is the confines of the home venue truly an advantage or is this simply a misconception? Researchers from Spain and Portugal looked at 10 years worth of domestic league tables to find out if there is actually an advantage to playing at home.

The study included 10 years of domestic league competitions held in Europe (2000-2010). The analysis was limited to the highest league category in each of the UEFA countries. Their sample included a total of 111,030 matches in 52 countries. In short, the researchers noted the number of games won, drawn and lost by the home team. They then calculated to percentage of available points earned by the home team (3 for a win, 1 for a draw, 0 for a loss).

The results showed that the home team earned an average of 55.6% of the available points, indicating a significant home advantage. In terms of individual countries, 32 of the 52 UEFA countries showed a statistically significant home advantage. The strongest home advantage was found in Bosnia-Herzegovina (76.1%). Other notable countries that had significant home advantages were, England (55.7%), Spain (55.5%), Germany (55.8%), Italy (56.0%) and France (56.8%).

A few countries had a home disadvantage, including Lithuania (49.1%), Northern Ireland (48.8%), Malta (48.0), Andorra (47.1%) and San Marino (45.5%). However, these disadvantages were not statistically significant.

When comparing home advantage over the 10-year study period, there is a trend for the advantage to lessen. During the first season (starting in 2000), the percentage of points won by the home team was 56.9%. In the final season (ending in 2010), the value was 54.8%.

They also used UEFA rankings over the 10 seasons to determine a strength coefficient for each country. As it turns out, the home advantage is slightly greater in the top 10 ranked countries than in the bottom 10. In fact, the top 10 countries all had statistically significant home advantages, whereas, only 1/3 of the bottom 12 showed this trend.

If we take the data from the article and look at the percentage of matches won, we find home team wins 47.2% of the matches played, draws 23.5% and loses 29.3%. That works out a home field wining percentage of 59.0% (draws count as a 1/2 win and 1/2 loss).

There are several reasons why one would expect a home advantage. Familiarity with the home venue, crowd noise and lack of travel are a few. In 2007, researchers suggested that for every 10,000 fans attending, there is an increase in 0.1 goals scored. Unfamiliar locker rooms, field sizes, altitude, local weather can also adversely affect visitors more so than the hosts. Some studies also suggest that there may be a home bias in officiating. Thus, it is not surprising that home teams earn more points than the visitors.

Back to the original question posed at the top of this post. Is home advantage really an advantage? The authors conclude that there is a significant home advantage in the highest leagues in Europe. Home teams earn slightly more than 55% of the available points and have a wining percentage of 59%. This trend has held for the past 10 years. Also, the top leagues tend to have a stronger advantage than the lower ranked leagues. So yes, home advantage is truly an advantage.

Reference

Garcia MS, Agular OG, Marques PS, Tobio GT, Fernandez Romero JJ (2013) Calculating home advantage in the first decade of the 21st century UEFA soccer leagues. Journal of Human Kinetics, 38: 141-150.
Posted by Jay Williams, Ph.D. Labels: Strategy

Match Analysis and the Recovery Process

Match analysis has become an important tool in assessing team performance. Knowing team and opponent tendencies, individual player performance indicators, and markers of fatigue can help the coach or manager formulate match strategies and pinpoint team and individual weaknesses. Thus, it is not surprising that sport scientists are very interested in how match analysis can be used to improve their team and move them up the league table. In a new study, researchers at the Université Lille Nord de France and Lille Métropole Football Club took a different look at match analysis. They compared match analysis data to various performance indicators measured during three days of recovery. They found several interesting relationships between various player movements and prolonged decrements in physical performance. Their results have important implications for understanding the recovery process as well as preventing potential injury.

Match analysis was performed during four competitive matches to establish various playing actions completed by the players. At 1, 2 and 3 days following the matches, the players provided subjective ratings of fatigue and muscle soreness. They also underwent several physical tests of strength, sprint, and power performance. Data obtained at each recovery interval were compared to baseline measurements taken earlier in the season. During the post-match recovery period, players continued their regular training routine but were asked to avoid recovery treatments such as ice baths, compression garments and massages.

During the three-days after the match the players reported several perceptions. They felt a greater sense of fatigue at the 24-hour mark that subsided by 48 and 72 hours. They also reported increased muscle soreness across all three post-match days. This sensation of muscle pain and discomfort was associated with increased blood creatine kinase levels, a key indicator of muscle damage.

In terms of physical performance, power output was decreased by 5-6% over the course of the recovery period. Both peak sprint speed and vertical jump measures were depressed for up to 72 hours post-match. Also, hamstring strength in both the dominant and non-dominant legs were reduced for the duration of recovery. The researchers found between 6 and 8% reductions in dynamic strength of these muscles.

Match analyses showed that the changes in muscle soreness were most closely linked to the number of short sprints performed during the match. Fatigue and physical performance were linked to the number of hard directional changes and the number of tackles executed. This is not surprising. Sprinting and changing directions requires rapid acceleration and deceleration. Both of these actions require forceful concentric and eccentric muscle contractions. We’ve known for years that eccentric or lengthening contractions leads to both fatigue and delayed onset muscle soreness. However, this is the first study to link movement patterns and player actions during a match to the degree of soreness and physical performance decrements.

The finding that hamstring strength was depressed for up to 72 hours post-match has important implications for the recovery process as well as the risk of anterior cruciate ligament injury. As we’ve discussed previously on the SSO, ACL injuries is a growing problem. Recognizing, understanding and correcting risk factors can go a long way in preventing injuries. We’ve known for years that both weak hamstrings and muscle fatigue increase injury risk. When various movements stress the ACL, the hamstrings contract to help stabilize the knee. With fatigued or weakened hamstrings, this aspect of stability is reduced and the potential for sustaining and injury increases.

This study shows that hamstring muscle fatigue may persist for up to 72 hours after a match. Many college, high school and youth club schedules require multiple matches to be played with as little as 24 hours of recovery. The Atlantic Coast Conference has adopted a Thursday and Sunday schedule of women’s matches, leaving 72 hours of recovery from the first match to the second. Other teams and conferences used a more congested format, a Friday and Sunday schedule. Based on the current research article, it is quite possible that many players are not fully recovered by the start of the second match. That is, hamstring strength may remain depressed, raising the risk of ACL injury. This may be particularly true if the preceding match required players to execute an abnormally high number of short sprints and changes in direction.

Unfortunately, there is little information on injuries occurring during this schedule of matches. And, to be truthful, we don’t know if more injuries occur during the 72 hours after a difficult match. Despite this, coaches should take caution and consider this information when faced with a congested calendar. At the very least, coaches should be aware that player performance may suffer for up to 72 hours after a difficult match. Strategic use of player substitutions could reduce the number of key player movements (sprints, direction changes) and may be able limit fatigue in the initial match. Targeted exercise recovery regimes may also speed the recovery process between matches. In this study, players were not allowed to use treatments such as ice baths, compression garments or massage. While the research is not completely clear on how well these techniques actually aid the recovery of muscle force, some argue that they may offer some benefit. Finally, research is clear that a proper nutritional recovery strategy can enhance the recovery process. High carbohydrate foods and beverages containing some protein taken immediately after the match are critically important to recovery. Continuing the process with nigh carbohydrates meals and plenty of fluids is important as well.

Understanding how the physical demands of the match can impact subsequent performance is important over the course of a season. And, recognizing how a strategic recovery process can affect both performance and injury risk can go a long way in the team having a successful season.

Reference

Nedelec M, McCall A, Carling C, Legall F, Berthoin S, Dupont G (2013) The influence of soccer playing actions on the recovery kinetics after a soccer match, Journal of Strength and Conditioning Research, DOI: 10.1519/JSC.0000000000000293.

World Conference on Science and Soccer

One on the goals of the Science of Soccer Online is to bridge the gap between researchers who study the science behind the game and coaches who want to train their players using cutting-edge methods and techniques. In 2014, the 4th World Conference on Science and Soccer (WCSS) will be held for the first time in the United States. The conference will bring together individuals who are interested in the study and/or practical performance of soccer players, including sports scientists, coaches, strength and conditioning specialists, sports physiotherapists, exercise physiologists, professors and students. The overall goal is to bring some of the world’s best scientists, coaches, and practitioners into a conversation about how research can improve performance on the pitch.The conference provides the scope to share the knowledge of scientific research, technical knowledge, and experience to improve the game of football. It also provides overviews and current issues that the players are facing on the field. the conference brings together 20 nations and 300 participants together on the same platform. This page will give you more information about the conference.

The WCSS will be held June 5-7, 2014 and is hosted by the University of Portland and Program Chair, Dr. Terry Favero. This is the first time the conference will be held in the United States, but over 300 participants from over 30 countries are expected to join the US audience. Previous host cities are Ghent (Belgium), Port Elizabeth (South Africa), and Liverpool (United Kingdom).

Anyone who is interested in the scientific study and/or the practical performance of soccer, from grass roots to the elite professional level, is invited. This includes academics, sports scientists and exercise physiologists, full and part-time youth coaches, strength and conditioning specialists, athletic trainers and physiotherapists, as well as administrators, teachers and students. A broad range of interests will foster translating research results from the laboratory to the useful applications on the pitch.

The program includes speakers and topics such as:

Plenary Speaker: Rasmus Ankersen, Author of The Gold Mine Effect: Crack the Secrets of High Performance
Managing Training Load: Aaron Coutts, University of Technology Sydney
Soccer Nutrition: James Morton, Liverpool John Moores University
Soccer and Health: Peter Krustrup, University of Exeter
Match Analysis: Chris Carling, LOSC Lille Métropole Football Club
Recovery From Training/Matches: Shona Halson, Australian Institute of Sport
Sport Psychology: Gier Jordet, Norwegian School of Sport Sciences
Youth Specific Training Model: Martin Bucheit, Alberto Mendez-Villanueva, Aspire Academy
Athletic Skills Development and Soccer: Jan Willem Teunissen, Ajax Youth Academy/Geert Savelsbergh, University of Amsterdam
Soccer Biomechanics: Hiro (Hiroyuki) Nunome, Nagoya University/Ewald Essig, University of Duisburg-Essen
The Numbers Game: Why Everything You Know about Soccer is Wrong. Christopher Anderson, Cornell University
Match Analysis: Ben Knapper, Lead Performance Arsenal FC
Injury Prediction Model: Dave Tenney, Head Fitness Coach and Sport Scientist Seattle Sounders

Other topics of discussion will include:

Training and testing
Performance/match analysis
Women’s soccer
Sport psychology
Talent identification
Youth development
Injury prevention
Biomechanics
Soccer and health
Lab to field sessions focused on:
– Speed and Agility for Soccer Athletes
– Managing Training Load During the College Soccer Season
– Strength Training for the Soccer Athlete

Please join us for this exciting and informative event! For more information on the WCSS, click here.
Posted by Jay Williams, Ph.D.

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