Nutrition, Science

Electrolytes in Soccer – Everything You Need to Know

Written by Soccer Fitness Internship Student Kayleigh Mines, edited by Richard Bucciarelli.


Electrolyte replenishment is very important during high intensity and/or long duration activities such as soccer. It is important to maintain hydration during these activities to sustain electrolytes levels. Sustaining electrolyte levels will allow optimal performance and ideal health for the athlete.

Before understanding how to replenish electrolytes we have to first understand what electrolytes are. An electrolyte is a substance in the body that produces an electrically conducting solution when dissolved in water, or H2O. Electrolytes carry an electrical charge and are essential for everyday life. They are found in your blood, urine and bodily fluids. Maintaining the optimal electrolyte balance aids in your body’s blood chemistry, muscle activity, and other metabolic processes. All higher forms of life need electrolytes to survive (Christian Nordqvist, 2016). In our bodies we carry electrolytes. These electrolytes comprise of minerals that include; sodium (Na+), potassium (K+), calcium (Ca2), magnesium (Mg2+), chloride (C1), hydrogen phosphate (HPO42-), bicarbonate (HCO3), and hydrogen carbonate (HCO3).

We need electrolytes in our bodies for many reasons. These reason include; regulating our nerve, organ, cell, and muscle functions, temperature control, hydration/fluid levels, glucose metabolism, ion and fluid transportation, pH levels, blood pressure, and aid in rebuild any damaged tissues. If we experience imbalanced electrolytes it is because the amount of water in the body has changed, either it is dehydrated or overhydrated. We usually experience this through exercising where we tend to sweat more frequently and heavily. If low or imbalanced electrolyte concentration occurs you could experience symptoms such as; muscle weakness or spasms, irregular heartbeat, blood pressure change, confusion, fatigue, nausea and more severe symptoms like chest pain, seizures or lethargy convulsions. Reasons for imbalanced electrolytes can be caused by kidney disease, vomiting over a prolonged period of time, severe dehydration, congestive heart failure, acid/base pH imbalance, eating disorders, and some drugs such as diuretics or ACE inhibitors (Christian Nordqvist, 2016). Treatment for imbalanced electrolytes include either increasing or decreasing fluids and mineral supplements may also be given by mouth or intravenously if the body is heavily depleted.

Electrolytes come from the foods and liquids we consume. These foods and liquids contain sodium, calcium, potassium, magnesium, chloride, phosphorous, and bicarbonate, all the key components that make up electrolytes. All of these components have a certain role as an electrolyte that is beneficial to the body. Sodium helps to control fluid in the body that is necessary for optimal muscle and nerve function along with impacting blood pressure. Calcium is important for the movement of nerve impulses and muscle. Potassium helps in regulating the heart and blood pressure along with aiding in transmitting nerve impulse to allow for necessary muscle contractions. Magnesium is essential in helping to maintain heart rhythm, regulating blood glucose (blood sugar) levels, and enhancing the immune system. Chloride is vital for providing equilibrium to the acidity and alkalinity, which helps to maintain optimal pH levels along with helping in digestion. Phosphorous is essential in aiding in the production of tissue growth and repair by providing energy to the cells. Lastly, bicarbonate’s role is to correspondingly aid in the body maintaining healthy pH levels along with regulating heart function (Cotter, Thornton, Lee & Laursen, 2014). Each of these components aid in the health of each individual and maintaining them will only prove their worth.

To maintain or restore electrolytes back to their optimal levels there are a few things we can do. Paramount among these is maintaining your body’s fluids by drinking plenty of water. It is advised that athletes drink 8 ounces of water 20 to 30 minutes before starting their exercise, drink 8 to 10 ounces of water every 10 to 20 minutes during exercise, and drink 8 ounces of water no more than 30 minutes after exercise (WebMD, 2016). You can also maintain electrolytes through your diet. Replacing electrolyte loss through eating foods high in the minerals that make up electrolytes such as; bananas high in potassium, salty snacks like nuts containing sodium, phosphorus, and chloride, milk products high in calcium, and leafy greens high in magnesium (Isabel Smith, 2014). Athletes can also replenish their electrolytes though drinking sports drinks such as Gatorade or PowerAde that contain carbohydrates (CHO) and electrolytes. These drinks replace sweat that has been loss during exercise along with aiding to retain fluid in the body/blood. You should only drink sport drinks when an exercise exceeds past 30 minutes since you need to replace CHO that have been used for energy and electrolytes that have been depleted through high sweat volumes. However there are “pro’s” and “cons” of consuming sport drinks. Pro’s include; replacing fluids lost during high intense exercise, replacing CHO used for energy aiding in bring blood glucose back up to normal levels, replacing protein, and the fact that in general the drinks are easy to digest, taste good, and replenish vitamins and minerals. The cons include; the acidity in sports drinks can dissolve teeth, they are expensive, they are often used to replace water when unessential, they are high in sugar, they may contain caffeine, and some also have unproven claims such as; improving one’s speed, endurance, concentration, agility, and overall athletic performance.  Companies who market and sell sports drinks do not have factual proof to back up these performance-enhancing claims (Lifescript, 2016).

With these alternatives it proves that there are different possibilities in maintaining or replenishing electrolytes loss during high intense, low intense, or long duration exercises. Keeping electrolytes in mind when exercising. Making it a priority to maintain electrolytes at optimal levels, so as an athlete you can perform the best you can in any activity you may be performing in.

Fitness, Science, Technology

The Soccer Fitness Drop Jump Test – An Efficient and Effective Way to Measure Agility in Athletes


Written by Soccer Fitness Staff member Alexandra Giannone, edited by Richard Bucciarelli.

The drop-jump test is a vertical plyometric exercise that is used to evaluate an individuals
explosive power (Ebben & Petushek, 2010) as well as a measurement of their eccentric leg
strength and agility.

To perform a drop-jump one must stand on box, with one foot hanging off the edge and their hands on their hips. The individual will then step down, hitting the ground with both feet, once contact with the ground is made they must then rapidly explode and jump up
as high as possible.

For a more explosive jump it is crucial for them to utilize their stretch shortening cycle (SSC) to its full capacity. When the eccentric/concentric phases of a movement are coupled, a more powerful contraction is produced. During the eccentric phase, active muscles are pre-stretched and absorb energy. Part of this energy is temporarily stored and then reused during the concentric contraction phase of the SSC. A short transition between the eccentric and the concentric phase is necessary for this elastic energy to be used optimally (Flanagan & Comyns, 2008).

The ground contact time in these plyometric exercises are an important variable for strength and conditioning. Athletes that wish to increase maximum jump height can benefit from longer ground contact times, allowing them to generate maximum force and maximum jump height. However, an athlete that needs to improve their maximum velocity sprinting speed would require the plyometric exercise to have shorter contact times.

Examining the ground contact times of an athlete during these plyometric exercises will give a coach/trainer an excellent indication of whether the exercise being performed is beneficial to the athletes’ specific sport. In a recent study examining the use of the drop jump, male athletes were found to have had shorter contact times, and produced the highest maximum and and mean mechanical power, as compared to female athletes (Walsh, Arampatzis, Schade, & Brüggemann, 2004).
To evaluate an individual’s drop jump performance and explosive strength, their reactive
strength index (RSI) must be measured (Ebben & Petushek, 2010). RSI is equal is jump height (JH) divided by contact time (CT) (RSI = JH/CT). CT is defined as the time between the first foot contact with the force platform and when the subject’s feet left the platform. JH is characterized as the time between the subjects feet leaving the force platform and when they contacted it again (Stephenson, Ebben, Flanagan, & Jensen, 2011).

Drop jump and reactive strength index can be assessed using a variety of methods. At Soccer Fitness, athletes have the opportunity to be assessed using OptoJump, an
innovative system analysis and measurement, consisting of a transmitting and receiving bar. The system detects any interruptions in communication between the bars and calculates duration (ex. jump height and contact time) A system like this allows for assessment and optimization of performance to the world of competitive sport (Microgate, 2014).

Agility is a term that is very controversial due to the result of multiple factors and various
disciplines in sports science. A biomechanist, a motor learning scientist and a strength and conditioning coach can all have different perspectives as to what influences agility performance.  A comprehensive definition of agility would recognize the physical demands (strength and conditioning, cognitive processes (motor learning) and technical skills (biomechanics) (Sheppard & Young, 2006).

In order to assess agility the movement/exercise must feature an element of
reaction and/or decision-making in addition to the particular change of direction. There are multiple tests that determine an individuals change in direction ability, some include, the Illinois test, 5-0-5 test, and the Zigzag run test. However, these tests do not show a significant relationship with one another. This means that an athletes scoring on different change of direction tests depends on the movement demands of the test protocol. In addition, change of direction may also differ depending on whether the athletes cutting movements are executed with their dominant or non-dominant leg (Gamble, 2012). The drop-jump was also compared to a 20 metre sprint exercise that contained three- directional changes and was found that there was no significant correlation between the two. It was suggested that reactive strength, due to the SSC involvement, is a better predictor and has a stronger relationship with change of direction speed (Young, James, & Montgomery, 2002).
Overall, strength and power measures have an influence on change of direction speed
(CODS), but this relationship is only observed when comparing tasks involving CODS over
short distances. Sports that involve these short distances, such as badminton and soccer, strength and power have a stronger relationship with CODS than athletes who perform higher speeds over longer distances with directional changes (Negrete & Brophy, 2000).

Fitness, Science

The Problem With “Reaction Time” Training in Soccer – And What to do About It

There is girl in the United States that can strike out any Major League Baseball player.  Easily.  This is not a joke.

In The Sports Gene, a 2013 book written by David Epstein which should be required reading for any sports scientist or fitness coach working with athletes, the author discusses sport-specific anticipatory and reaction abilities, and how they apply to the learning of sports skills.

Epstein describes a famous United States National Women’s Softball pitcher named Jennie Finch.  She played some exhibition games in the early 2000’s where she pitched against top men’s baseball players like Albert Pujols, Mike Piazza, and Barry Bonds.  Although all of these players are expert hitters, who presumably possess exceptional “reaction” skills that allow them to routinely hit 100+ mph overhand fastballs in their own sport, none of them were able to hit Jennie Finch’s 50-60 Mph, underhand, softball pitches.

How can it be that the professional athletes considered to have the world’s best “reaction time” cannot hit an underhand pitch travailing at 1/3rd the speed they are accustomed to?  The reason Finch’s pitches are un-hittable for Major League Baseball players is not because she is possesses any super-human strength or power.   It is because men’s baseball players – even the elite ones – have no experience in softball or in facing underhanded softball pitches.

Over time and through the accumulation of repetitive practice, Major League ballplayers have been exposed to hundreds of thousands of overhand fastball pitches, and as a result they have developed the ability to accurately predict where the ball will end up – to “anticipate” – at about the time the pitcher cocks his arm backwards.  If the same players were to wait until they could actually see where the ball from a fastball pitch would travel, and then try to “react” to it, the ball would already be in the catcher’s glove by the time they would have started their swing.

As a function of their training and experience, elite professional baseball players are able decide where and how they are going to swing at fastball pitches – again, to “anticipate” rather than to “react” – with enough time to actually hit the ball.  This unique anticipatory ability, which has been studied extensively in sports science research, has been proven to be much faster and more developed in professional versus amateur ballplayers, meaning that elite players are able to “see into the future” far sooner than sub-elite players, and the extra time gained from this ability allows them to have a much higher success rate in hitting the ball.

Unfortunately, because these same players have never been exposed to underhand softball pitches, they have not accumulated enough experience to develop the ability to accurately predict where Finch’s underhand pitches will go quickly enough to react to them.  Their anticipatory skills are very specific to the type of movements and plays they have been exposed to in their particular sport, and are not effective in softball.  So they strike out.  Every time.

The Sports Gene cites several different research studies that have examined elite athletes in several different sports (including soccer) and the results are always the same.  Elite professional athletes are able to predict – accurately – what is going to happen in their own sport before it actually happens.  And they are able to do it quicker than their opponents.

There are a few caveats, however.  Firstly, elite athletes’ anticipatory skills in their own sport are not transferable to other sports.  In all the studies cited in The Sports Gene, when elite athletes (with exceptional anticipatory ability from their own sport) were asked to predict the outcomes of plays from other sports, they showed no significant differences in predictive ability as compared to average, sub-elite performers (and in many cases they were worse than sub-elite performers).  Furthermore and perhaps more importantly, elite athletes from every sport who were tested, including soccer, were not shown to have any significant differences in actual “reaction time” – the time taken from the perception of stimulus to the initiation of movement reacting to the stimulus – than either sub-elite athletes, or even from non-athletic members of the general population.

Thus, anticipation, and not reaction time, is the ability which separates elite from sub-elite athletes (and it is also the reason than no Major League ballplayer will ever hit Jennie Finch’s underhand pitch).

Armed with this information, how can soccer coaches and fitness coaches train their athletes to improve sport-specific anticipatory skills?  The good news is that the answer is very simple.  Research and science in skilled performance and motor learning has indicated that the best way to improve these abilities in athletes is not to use fancy “reaction time” or “agility” drills.  Instead, players need to play soccer, or conditioned small-sided versions of the soccer, as much as possible.

Through repetitive exposure to hundreds of thousands of instances where soccer-specific anticipation is required (for example, determining where a pass from a teammate or opponent will end up), players can develop and improve their ability to accurately predict what will happen, position themselves accordingly, and increase their chances of success.

When designing training sessions and exercises, coaches and fitness coaches should determine which anticipatory skills they would like to develop, and then select an appropriate small-sided game with the appropriate conditions (for example, field size, number of players, rules of the game, etc.) in order to help them to bring these skills out in their players.  If the goal of training is to the ability to dribble and beat an opponent forwards, use a 1 vs. 1 game with players attacking defenders head-on.  If the goal is to improve players’ ability to ability to connect passes and make combinations such as wall-passes, use a small-sided game like 3 vs. 3 or 4 vs. 4, and perhaps add one extra attacker to help teams in possession outnumber defenders around the ball. If the goal is to improve a goalkeeper’s ability to stop shots from medium-range, use a small-sided game with large goals and a relatively short field length that will encourage players to shoot.  You get the picture.

Eventually, through the accumulation of enough repetition and experience, players will improve their ability to accurately predict what will happen (“anticipate”), and take the action (“react”) that will give them the highest chances of success.  They will decrease the mistakes they make by improving their positioning and decision making.  And the team will play better as a result.

I’d love to hear your thoughts about this topic.  Drop me a line here to get the conversation started.


Article – “Leicester City: The Science Behind Their Success” at

Leicester City are the 2016 English Premier League Champions.

Last Sunday, May 1st, after having drawn 1-1 with Manchester United the day before, they confirmed themselves as champions when Tottenham Hotspur drew 2-2 with Chelsea, mathematically eliminating their closest rivals in the league table.

Leicester’s run to the Championship this season has been described by many in the media as a “fairly-tale” for a number of reasons, not the least of which being the fact that the club has won despite having the league’s lowest annual payroll, and also because it is basically devoid of star players, having assembled their squad with players the other Premier League clubs – and even some of the 1st and 2nd Division clubs in England – didn’t want.

But was their Premier League title really just an incredible case of good fortune, or was it the result of carefully planned, meticulously executed strategies, including physical fitness and sports science strategies?

Below is a link to an excellent article written by Alistair Magowan, and posted to on Wednesday, May 4th, titled “Leicester City: The Science Behind their Premier League Title.”  In this article, Magowan outlines the incredibly positive impact that Leicester’s sports science staff, comprising a team of experts in the fields of strength and conditioning, performance analysis, nutrition, and sports psychology, have had on both the individual players’ as well as the team’s performance.  Some of the highlights of this impact in the 2015/2016 Premier League season include:

  • Having the fewest total number of injuries this season
  • Having the least amount of time lost due to injury this season
  • Using the fewest number of players this season
  • Having the highest number of counter-attacking goals, and the highest number of counter-attacking shots on target, this season

Magowan goes on to highlight several of the strategies used by Leicester’s sports science team, including managing training volume and intensity, performance monitoring during training and match play, recovery and regeneration methods, nutrition and hydration, and psychological skills training.  This quote from Darren Burgess, former Fitness Coach for Liverpool FC who was interviewed as part of the article, neatly sums up the importance of a good sports science team in a professional club:

 “Quite often sports science is not used to its full potential but we’ve seen the results at Leicester and I would be stunned if other teams don’t jump on board…  This is one of the biggest upsets in the history of world sport and, hopefully, it will change some of the beliefs in football about the impact good sports science can have.”

Below is a link to the full article.  I hope you enjoy it and as always, welcome your comments and feedback.