Halftime, Carbohydrates and a Re-Warm Up

Halftime of a soccer match is a short break between two periods of intense activity. It’s also a time for players to recover from the first period, re-hydrate, take in a few carbohydrates and a receive feedback and instructions from their coach. All squeezed into a 10-15 minute break. As such, different coaches may approach halftime differently. What is the best strategy for halftime? What should players do to recovery quickly and prepare themselves for the next period of play? Two recent studies shed some light on these questions. They give some insight on diet, hydration and physical activity practices that may help players maximize their second-half performance.

In the first study, Dr. Mark Russell and his colleagues looked at how carbohydrate ingestion during a match (sports drink) affects blood glucose (Russell et al., 2014). They found that drinking 150-200 ml (5-7 oz) before and every 15 minutes during the match and at halftime had a positive effect on blood glucose. But, this effect was found only at the end of the first period. During the second period, when blood glucose levels begin to wane, the carbohydrate drink had no effect.

Although carbohydrate is known to influence the physical proficiency and decision making of a player. So the recommendation is made to change the halftime food habit practices to enhance the player’s performance. Research is going on to find out alternatives to carbohydrate drinks which can provide more energy to the players. Click on imp source to read more about this.

One of the more interesting aspects of the study is the finding that blood glucose declined during the halftime break, despite the fact that the players drank a carbohydrate beverage five minutes into the 15-minute break. Thus, the players started the second period with fairly low blood glucose levels – not considered hypoglycemic, but close. Low blood glucose at the start of the second period could have a several negative impacts on their performance in the initial minutes. Slow, lethargic and fewer high intensity efforts are characteristic of low blood glucose.

Blood glucose during exercise and recovery is influenced by a number of factors. Insulin is a potent hormone that is released in response to high blood glucose. This promotes glucose uptake by fat and liver cells. Epinephrine (adrenalin) has the opposite effect, it stimulates the liver to break down its glycogen and release it into the blood as glucose. Cortisol has a similar effect. During exercise, especially intense exercise, epinephrine and cortisol levels in the blood are increased. In addition, insulin release is suppressed. This combination stimulates glucose release from the liver and prevents its uptake by fat cells. Thus, blood glucose levels are elevated. This provides the muscle with an ample supply of carbohydrate for its energy needs. In addition, hypoglycemia is prevented.

For the most part, the body views halftime as recovery. Things change during recovery. Within minutes of stopping exercise, epinephrine and cortisol levels subside and insulin levels rise. This stimulates glucose to move into the live (and muscle) to be stored as glycogen. When a carbohydrate sports drink is taken in and glucose enters the blood, the insulin response may be greater. This in turn, could lead to greater glucose uptake by the liver and reduced blood glucose or a “transient hypoglycemia”. This may be what happened during the halftime period of Dr. Russell’s study. In this case, the carbohydrate drink per se did not cause hypoglycemia, but it did not prevent the drop in glucose during recovery.

So, what should a player to do during halftime – drink carbohydrates or not? How can an athlete re-hydrate and replenish energy stores without sacrificing performance. Some insight might be gained from the second study.

This study focused on the benefits of a re-warm up during halftime (Edholm et al., 2014). During the 15-minute halftime of a competitive match, the researchers asked one-half of the players to take on a traditional passive recovery (control group). The other players were asked to rest for 7 minutes then do some low to moderate intensity jogging and calisthenics for the remaining 7 minutes (re-warm up group). In a second match, the players reversed their halftime strategy.

The researchers found that sprint and vertical jump performance declined during the first half. This was expected. However, during the 15-minute halftime interval, performance further declined in the control group but not in the re-warm up group. Thus, the re-warm up group was better prepared for the second period. Also, the re-warm up group maintained greater ball possession and had less defensive running than the control group. Thus a 7-minute, active re-warm up during halftime benefited player performance. Other studies have shown similar benefits of a re-warm up. In terms of match performance, it’s easy to envision how being physically ready to compete at the start of the second half could lead to a fast start and goal scoring opportunities.

One concern of an active re-warm up is that the amount of energy expended could impact performance later in the match. The researchers (and others) found that this is not the case. Seven minutes of low to moderate intensity activity had no negative impact on markers of fatigue such as running distance and intensity or exercising heart rate in the later stages of a match.

So, what do these two studies offer for a halftime strategy? Instead of having players enter “recovery mode” during halftime, they simply transition to and from a period of light activity. A key benefit of this approach to halftime might be suppression of insulin and maintenance of epinephrine. Combined, this could help the player maintain blood glucose levels, especially if he/she is taking in a carbohydrate beverage. Thus, the low blood glucose state that Dr. Russell found might be prevented by an active re-warm up. It should be pointed out that there is no research on combining a re-warm up AND sports drinks during halftime. So, this idea remains a bit untested.

As for a halftime strategy… First, blood glucose levels decline during the halftime recovery and this could affect performance at the start of the next period. Second, a halftime re-warm up seems to benefit performance, particularly at the start of the second period without negatively affecting the later stages of the match. It is possible that this effect is due, in part to maintaining blood glucose and avoiding the negative effects of hypoglycemia. Based on this, coaches should consider the following strategy. Provide the players with a carbohydrate beverage at the start of halftime. Have them rest and recover for the first few minutes while they begin drinking. Then, begin a low intensity re-warm up while they finish their drink. This should better prepare them for the second half compared to the traditional passive halftime. They should be ready for a fast start once the whistle blows. However, as with any new strategy, it’s always best to test this out on players during training and scrimmage matches. Sometimes, the theory doesn’t always translate into reality!


Russell M, Benton D, Kingsley M (2014) Carbohydrate ingestion before and during soccer match play and blood glucose and lactate concentrations, Journal of Athletic Training, 49(4):447-453.

Edholm P, Krustrup P, Randers MB (2014) Half-time re-warm up increases performance capacity in male elite soccer players, Scandinavian Journal of Medicine and Science in Sports, in press, doi: 10.1111/sms.1223
Posted by Jay Williams, Ph.D.

Hamstring Strength, Fatigue and Knee Stability

The incidence of anterior cruciate ligament injuries is all too common. In the U.S., it is estimated that as many as 200,000 injuries occur per year. Most of these are non-contact, meaning that movements associated with activity (landing, stopping, turning and cutting) stress the ACL, causing it to rupture. Some also estimate that women are five to eight times more susceptible to ACL injury than their male counterparts. Over the past 20 years, we have begun to understand the mechanisms of these types of injuries as well as ways to reduce risk and prevent ACL tears.

ACL or anterior cruciate ligament is one one the most important ligament present in the knee. When the injury occurs the person can feel or hear a pop in the knee, the symptoms of swelling, pain and unable to take the upper body weight will happen. Depending on the severity the orthopedic doctor will suggest the treatment. my company gives you more insight into ACL.

A key risk factor is weak hamstring muscles. Weaker hamstrings increase risk. A new study shows that when hamstring strength is reduced by fatigue, the ACL is subjected increased stress, particularly when planting the foot and cutting. the study emphasizes the need for improving hamstring strength as an important means of lowering injury risk.

Seventeen active females performed a series of sidestep cutting maneuvers before and after undergoing a fatiguing bout of hamstring contractions. For the cutting maneuver, they were asked to run towards a force place, plant their right foot and cut to the side at a 45 degree angle. This was done several times. After the first round of trials, the subjects performed a series of hamstring contractions (hamstring curls) designed to induce fatigue and reduce hamstring strength. Afterwards, they repeated the cutting maneuvers.

The subjects were fitted with several joint markers and electrodes that were used to measure movements and muscle activity. Computer measurements of muscle activity, limb and joint movements were then entered into a three dimensional knee model to estimate loads placed on the ACL.

The figure (taken from the study) shows the load on the ACL during the sidestep cutting maneuver. When the foot touches the ground, ACL load increases, reaches a peak, then decreases at the athlete pushes off and the foot leaves the ground. The red line represents ACL load before the hamstring muscles were fatigued. The black line is the load immediately after. Notice the difference in peak force. The data show that when hamstring strength was reduced, the load on the ACL was increased by 36%. Most importantly, the forces exerted in the sagittal plane (viewed from the side as the tibia slides forward) and in the frontal plane (as the tibia undergoes knee valgus) were increased.

What seems to contribute to increased load on the ACL is decreased hamstring strength. During the cutting maneuver, peak forces produced by the hamstrings were reduced by 27%. With the hamstrings providing less force to stabilize the knee, the ACL has to shoulder more of the load.

The researchers also found that cutting while fatigued reduced the amount of hip, knee and ankle flexion. This in turn, increased the impact force as the foot hit the ground. This is, planting the foot with less hip, knee and ankle flexion causes it the “stop” more quickly, increasing impact. Increased impact forces add to joint stress and increase the load placed on the ligaments.

The key emphasis of the study is that when players execute a sidestep, cutting maneuver in a fatigued condition, weakened hamstring muscles can result in greater load placed on the ACL as well as higher joint impact forces. This increased load elevates risk of sustaining an ACL injury, possibly a ruptured or torn ligament.

We’ve known for years that weak hamstrings (especially relative to the quadriceps muscles) are a risk factor for ACL injures (link . While the hamstrings flex the knee joint, they also play an important role in stabilizing the knee and protecting the ACL. During a stopping or cutting maneuver, external forces along with the quadriceps muscle force can cause the tibia to slide forward, twist or undergo valgus movements (abduction or a knock-kneed position). This is referred to as “valgus collapse” and is one of the primary causes of non-contact ACL injury. The hamstrings are designed to counter these unwanted movements, pulling to tibia backwards and limiting rotation and valgus. Thus, weakened or fatigued hamstrings are less able to stabilize the knee and protect the ACL. As shown in the study, stress on the ACL is increased.

The take home message of this study is that strengthening the hamstrings and preventing fatigue should help stabilize the knee and prevent ACL injuries. It is this reason that ACL injury prevention training programs include strengthening the hamstring muscles. All of the programs advocated by trainers and therapists include some kind of hamstring exercises like the Nordic curls. By strengthening the hamstrings AND preventing them from fatiguing during a match, we may be able to reduce load placed on the ACL and lower the possibility of injury.

Research has clearly shown that ACL injury prevention programs such as the FIFA 11+ do help. Through persistent and diligent use of these programs, both the risk and incidence of injuries can be lowered (link, link, link). As mentioned earlier, more than 200,000 ACL injuries occur each year in the US. This is tremendous personal and financial burden. Also the potential for complications later in life such as osteoarthritis are high. Thus, any program that lowers injury risk should be strongly encouraged. In this case, an ounce of prevention is well worth a pound of cure.


Weinhandl JT, Earl-Boehm JE, Ebersole KT, Huddleston WE, Armstring BSR, O’Coner KM (2014) Reduced hamstring strength increases anterior cruciate ligament loading during anticipated sidestep cutting, Clinical Biomechanics, DOI: 10.1016/j.clinbiomech.2014.05.013.
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Labels: Current Research, Injuries, Training

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.


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.

To order your copy, CLICK HERE

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.


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!


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.


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

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
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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