Inter sex muscle activation differences

A study recently published in the journal of "Bone and Joint" has aimed to find the differences between males and females in their performance of football kicks, and relate that to the difference in ACL injury rates.

There is existing research which shows that females are more likely to suffer non-contact ACL injuries than males, however no direct cause for this has been established.

The study was carried out at Washington University School of Medicine, and was lead by Dr H Brophy, a former professional footballer.

The study involved 13 male and 12 female college football players. These athletes performed 5 in-step kicks, and 5 side foot kicks each, with their movements being recorded using 10 video cameras, 21 retroflective markers and 16 electrodes. The activation of 7 muscles (iliacus, gluteus maximus, gluteus medius, vastus lateralis, vastus medialis, hamstrings and gastrocnemius) were recorded in both legs, and the activation of 2 muscles (hip adductors and tibialis anterior) were recorded in the kicking leg. Muscle activation was measured as a percentage of maximum voluntary isometric contraction.


The Results

• In the kicking leg, males generated about 4 times as much hip flexor activation as females (123% in males compared to 34% in females).
• In the supporting leg, males generated more than twice as much gluteus medius activation (124% in males compared with 55% in females) and vasteus medialis activation (139% in males compared with 69% in females).
• An interesting observation made during the analysis was that, due to females having less activation of the hip adductors, their hips tend to "collapse" into adduction during the kicking motion, increasing the risk of injury.

Although Brophy states that this study doesn't establish a direct cause and effect relationship between muscle activation, knee alignment and ACL injuries, he did conclude by saying, "Activation of the hip adductors may help protect players against ACL injuries."

There are a number of positive and negative points to consider with this study. The main criticism i have of this study is the lack of information we are given concerning the way in which each kick was carried out (ie. was it carried out with maximal effort to replicate a shot, or an effort level to replicate a pass?). I also feel that the amount of information given concerning the athletes participating in the test is too vague. More knowledge of experience and skill level could affect the way these results are viewed.

There are positives as well though. The size of the study group (13+12) is impressive for a study working in such detail, which suggests reliability in the results. The study was also carried out at a reputable university, which lends to it's credibility.

Overall, i feel that this is a very interesting and important study. Although the results don't confirm a cause and effect relationship, i'm sure this study will act as a stepping-stone to more specific research being carried out in the future. In the mean time, i feel that Dr Brophy's suggesting to place a higher focus on strengthening muscles surrounding the hip should be taken very seriously, especially by females.



Ben Brown

Sports drinks explained

Sports drinks first appeared about 50 years ago, when American college teams began to experiment with them. These colleges found that combining salt, sugar and water aided athletic performance. Athletes experienced a slowing in the rate of dehydration, as well as energy sources being replenished. This allowed athletes to work harder, work for longer and think more clearly.

Today the choice of sports drinks is huge. The basic formula is still there though, with water, carbohydrates and electrolytes making the base. The developments made in sport science have made it possible to calculate what amount of each basic ingredient will be most beneficial to an athlete. It is proven that carbohydrate content must be between 5-8% to be effective, any less than this and it won't be enough to have an effect on performance, any more than this and the body's absorption of water will be impaired.

There is a common misconception that all sports drinks are the same. However, sports drinks can actually be put into three different categories. Each one is designed to suit a different occasion.

Isotonic drinks contain a balance of carbohydrates, electrolytes and water which is the same as in the human body. This can be absorbed at roughly the same speed as water, but has greater calorific value.

Hypotonic drinks have a carbohydrate and electrolyte to water ratio lower than that of the body's. This allows the fluid to be absorbed more quickly, but with less energy replenishment, making this drink suitable for sports where dehydration is likely.

Hypertonic drinks have a greater carbohydrate and electrolyte to water ratio than in the body, meaning the fluid is absorbed the slowest, but the energy replenishment is greatest. This form of drink is most effective when used as a post-exercise recovery drink.

Lucozade, Gatorade and Powerade all come under the category of Hypertonic drinks. It is therefore important to consider what your sport demands before choosing which sports drink to use, as well as which time you are consuming it (pre, during or post sport).



Ben Brown

EPO Abuse

EPO (Erythropoietin) is a hormone produced in the kidneys. Once produced, it travels via the circulation into bone marrow. It is here in the bone marrow where it is used to create red blood cells. 

By increasing the amount of EPO in the body, you also increase the number of red blood cells in circulation. The advantage of this is increased oxygen carrying capacity, which of course has a large effect on endurance performance.

Because EPO is a naturally occurring hormone, it is safe and legal for athletes to boost the levels of this hormone in their body through use of altitude training (real or simulated). However, injections of artificially created EPO are even more effective, making performance boosts of 5% or more possible. There are serious health risks associated with injecting EPO, as the blood becomes much thicker with the increase of red blood cells. The chance of a clot occurring increases as a result of this. In recent years, the death's of 20 cyclists are thought to have been caused by this clotting.

Unsurprisingly, EPO is on the IOC's list of banned substances. Though for many years, it was an extremely difficult substance to test for. The original test protocol used by the UCI was too simplistic to generate clear cut results. This test involved taking a blood sample and measuring the proportion of red blood cells within it. If a high proportion of hematocrit was found, then the athlete would not be banned, but they would not be permitted to compete on the grounds of it being a health risk. It wasn't possible for the UCI to ban an athlete from these results as there was no way of proving the increased hematocrit levels were achieved through altitude training.

One of the other major problems with this test, was that it was very simple for athletes to cheat. The test protocol meant that it was necessary to give athletes a 10 minutes to report to the medical team. Within that 10 minutes it would be possible to inject 500ml of saline into the blood stream, instantly bringing the hematocrit level down by a few percent.

The second form of EPO test is a urine test. This test is much more complex than the previous one, as it is designed to expose artificial EPO from natural EPO, as opposed to just measuring the effect any form of EPO has had on the body. This method, based on the technique of Immunoblotting, was first tested to see if it could detect the use of recombinant (artificial) EPO in patients who were using the drug. It was successful. The same technique was then used to examine 102 frozen urine samples from the 1998 Tour de France. This testing revealed 28 positives. The 14 samples with the highest concentration were then Immunoblotted. All were positive for recombinant EPO, Looking at these results, it would appear likely that at least 20% of competitors in this tour used EPO.

The third form of testing takes an alternative route to the detection of EPO abuse. Instead of looking at the EPO itself, it looks at the effects EPO has on red blood cells. The Australian Institute of Sport (who developed this test) found that a specific indicator of EPO injections is an increase in the of immature red blood cells (reticulo cells). Through analysis of these reticulo cells, it is possible to distinguish between athletes who have injected EPO, and athletes who have had a natural increase in red blood cells.

There are problems with both the urine and blood tests. It is speculated that the urine sample will only test positive if the last injection was carried out a few days before the test. Any more and the EPO will have disappeared from circulation, and therefore urine. The blood test is likely to be capable of detecting EPO use within the previous 2 weeks, as that is the length of time red blood cells take to mature.

So, despite each of these tests displaying frailties which a minority of athletes will take advantage of, it is encouraging to see that there is progression and rapid improvement in these techniques. As the testing methods have become more and more advanced, this minority of athletes appear to have moved onto blood doping, as the difference in red blood cells is much more difficult to detect. However, as testing techniques continue to develop, more and more cheats will be exposed, and (I'd like to think) sport will become cleaner and more transparent.

Ben Brown

The Cost of Extreme Endurance

Ultra-Marathons are running events which exceed 50 miles in distance. These races are aimed at the fittest, most experienced and mentally tough athletes. With such huge distances to cover on foot, injuries such as Tendonitis and Muscle tears are commonplace. However, according to research carried out by Liverpool John Moores University, athletes should have greater awareness and concern over the damage which can occur to the heart during a race.

LJMU studied a group of 25 runners (aged between 24-62) competing in the "Lakeland" race. 16 of the group competed in the 50 mile race, and the remaining 9 in the 100 mile race. All of the runners had at least 2 years of Ultra Marathon experience, and had trained specifically for the race. None of the participants had any known heart conditions. Each of the 25 subjects would be given a blood test, an ECG and would be weighed before and after the race.


The Results:

- Of the 50 mile competitors, the average completion time was 15 hours, and average weight loss was 2kg.

-Of the 100 mile competitors, the average completion time was 36 hours, and average weight loss was 3 kg.

-The post race blood tests showed that Troponin 1 levels rose significantly in 21 of the 25 subjects. In 3 of the runners, levels were high enough to suggest serious Cardiac damage.


The ECGs carried out before the race are said to have shown slow heart rates along with the electrical changes you would expect from an athlete.
In the post-race race ECGs, there were significant electrical changes in over 50% of the subjects. In some of the subjects, bizarre electrical changes were shown, not usually seen in normal ECGs (At rest or during exercise).

In Professor Somauroo's summary of the results, he stated that the study "suggests that running continuously over 50 or 100 miles may not be good for the heart". The closing statement of the study however, states that "There was no proven correlation between the changes in Cardiac Troponin 1 and the ECG changes."

This study appears to show that a large proportion of Ultra Marathon competitors are likely to suffer some degree of Cardiac Damage. It is however, important to consider how the study was carried out to decide how reliable the results are likely to be.


-The study group was small and therefore may not represent the general condition of Ultra Marathon competitors.

-The Lakeland race, where this study was carried out, suffered very difficult weather conditions. This could have affected the results.

-The subjects may have extremely varied levels of experience, as the only information we're given is that all subjects have been competing in Ultra Marathons for at least 2 years.

-The subjects were not given a full medical check-up prior to the race. This could mean that subjects with unknown heart conditions took part in the study and harmed the validity of the research.


It is expected that further data (Heart function levels) concerning this subject will be released at a later date. This data could go towards creating a greater understanding of the effects extreme endurance events have on the body, and how these adverse affects can be minimised.




Ben Brown

Heel-less Running Shoes

The development of new technologies designed to allow athletes to extend their career's to points previously thought to be impossible is rapid. As the average life expectancy increases, the market for sport equipment products designed for people of middle age and beyond has grown too.

One of the main problems for older athletes, is the frequent occurrence of injuries. The development of a new Heel-less running shoe intends to solve that problem, at least for runners.

Most running injuries suffered by older runners can be attributed to poor technique, with Over-Pronation, Supination and Heel-strike being widely accepted as the main causes. Each of these technical issues cause similar problems for the athlete's body, as they place large stresses on joints, tendons and muscles.

Supination or Pronation of the foot in a running stride mean that the landing force cannot be absorbed properly, increasing stress on the bones and joints. Heel-strike creates similar problems for runners, as the large impact force created by landing on the heel travels in a linear fashion directly though the heel bone, fibula and tibia, as well as placing a great strain on the achilles tendon.

Ideally therefore, a runner will land further forward on the shoe, allowing the force to be partially absorbed and spread by the sole, and the foot itself. This means the stress placed upon the joints is reduced.

The Healus running shoe forces the runner to run in this safer, more sustainable style, in much the same way that an insole would force an athlete to become more neutral in their running stride.

The Healus shoe also uses a shock plate to dissipate the force across the whole foot. This is used in combination with a sole constructed using "HelixVA." This material makes the sole more shock absorbant than the sole of a normal running shoe, meaning that the Heel bone is able to decelerate over a greater distance.

So, it would appear that the Healus technology could help athletes lengthen their running career's considerably through the prevention of injury. It is important to consider, however, that this product is still in the development stage, and that it may be long time before it enters production.

If this product can be designed to be as durable as standard running shoes, with the necessary testing to prove that the theory behind the design is correct, then they could have huge potential.

Ben Brown

The safety of AstroTurf

AstroTurf is the playing surface of choice at many schools and sports clubs in England. The surface's popularity can be put down to two main factors, AstroTurf requires less maintenance than natural turf, and is therefore cheaper. AstroTurf is also much more weatherproof than natural turf, making it available for use more of the time.

AstroTurf was first used in a major stadium in 1965, at the Housten Aerodome (Home of the Housten Texans NFL team). This playing surface was the only viable option, as natural turf would receive no sunlight in an indoor stadium. The use of Astroturf in NFL arenas became much more common, following the example of the Housten Aerodome.

There are however, a number of problems associated with the use of this playing surface. The rate of major injuries on AstroTurf is much higher than that of natural turf. The number of minor injuries such as "turf toe" and "turf burn", which are virtually non-existent on natural turf, are very common on this artificial surface.

There are two physical characteristics of AstroTurf which can be used to explain this high injury rate. The coefficient of friction is much higher on this surface than on natural turf. This means that a greater force must be exerted in order to move, explaining the high occurence of turf toe and turf burn.

AstroTurf also has a higher coefficient of restitution. This measurement displays a surfaces ability to absorb force. As a result of AstroTurf being less absorbent than natural turf, the occurance of broken bones and concussions is far more regular when athletes collide with the surface.

According to Dr. Mark Drakes, the first significant study into the effects of AstroTurf on injury showed that more series injuries were experienced by NFL teams on this surface compared to natural turf. The study also showed that (within natural turfs) the injury rate is also significantly higher on poorly maintained surfaces, and that the injuries on these surfaces showed a similar pattern to those found on AstroTurf, especially in cold weather areas.

With AstroTurf gaining popularity with schools, it is important to consider the injuries which may result from playing on this surface. The other options available to schools are to use natural turf, or to use a more technologically advanced artificial surface. However, both of these options come at a higher cost, one which schools and sports clubs in England appear to be unwilling, or unable to pay.

Ben Brown

Missing the point?

In 2005, as Lord Coe presented London's bid for the 2012 Olympic Games it became clear that providing a legacy of facilities, along with boosting participation rates were at the heart of the campaign.

Since 2005 however, England has suffered a deep recession. As a result of this recession, severe budget cuts were made in June of this year. One of the areas to suffer badly as a result of these cuts has been sport. Lord Coe's promises have been left looking particularly hollow as a result of the cuts.

Conservative sport minister Hugh Robertson admitted that the new budget has caused community sport to take "a major hit".

So how exactly has sport been affected?

-The building of new sports facilities for schools, that would have costed £6.05bn was cancelled partway through.
-Huge cuts to the £1bn local authorities spend on sport and recreation anually, all of which is discretionary.
-A £2bn cut to the total budget of the Department for Culture, Media and Sport by 2015.
-£65 million cut by scrapping the plan to provide free swimming for under 16s and over 60s, as well as cancelling the refurbishment of swimming pools.

The London 2012 Olympics are a great opportunity for Britain to catch up with the rest of the world and become more competitive for future World Championships and Olympic games. The Manchester Aquatics centre and Velodrome, left as a legacy from the 2002 Commonwealth Games have already shown how valuable facilities can be in providing community sport, as well as developing world class athletes.

It's a shame then, that the government appears unable to look at the importance of these Olympics in long term development.





Ben Brown

Injury prevention in design

When Nike Bauer launched the ONE95 skate in 2008, they claimed to have developed a new material, which they refer to as "ALIVE".

The designers' of the ONE95 spoke at length about superior thermoforming abilities of this material, allowing the outer shell of the skate to mould to the foot, as opposed to just the interior components as is the case with other skates.

The "ALIVE" material makes it possible for the outer shell to mould to the athlete's foot as it is not Epoxy based, as conventional skate shell materials are. This means that the material will become more malleable when the skates are baked.

A better fit to the athlete's foot is beneficial as it prevents power loss from slipping inside the boot, as well as making the skate more comfortable for the athlete.

However, the video shows another interesting quality of the "ALIVE" material. Both of these side impacts are from a standard puck travelling at 80mph. The Easton S15 is deformed to a much larger extent than the ONE5 skate. This suggests that a player is much less likely to suffer an ankle injury if they were to receive a side impact when wearing the ONE95 skate.

It would be unfair to assume that this reduced deformation is exclusively due to the ALIVE material, as the construction of the skate is just as important. I do feel however, that with ankle injuries being commonplace in Ice Hockey, that the design and material technology put into the ONE95 skate should be taken notice of by other manufacturers.

Ben Brown

All in the mind?

During long distance events, glycogen is the primary source of energy to the body. These stores of glycogen are of course, limited. This means that, as the stores of glycogen become depleted, a loss of performance is experienced.

I have recently been reading about the "Central Governed" theory. This theory suggests that fatigue is "Centrally" controlled by the brain, rather than the traditional view of being controlled "Peripherally" by the muscles.

This raises the question, is it a lack of glycogen in the muscles which causes an athlete's work rate to drop? Or is it the brain monitoring glycogen levels, and as they decrease, using nerve signals to reduce the work rate to make it more sustainable?

A recent study carried out at Ghent University claimed to test this "Central Governed" theory.

"Riders completed two separate time trials, riding for 1 hour in each. In the first time trail, riders rinsed out their mouths at regular intervals with a sports drink containing carbohydrates and electrolytes. They did not swallow the sports drink, the simply rinsed for 5 seconds before spitting the drink out. in the second time trial, the riders repeated this but used a "Placebo" which was sweetened drink with no actual carbohydrate content. The drinks were taste tested beforehand to ensure that riders could not tell the difference between either drink."

The results gained from this test showed "swilling with the carbohydrate drink increased power output by 3.7%, which equated to a 2.37 minute improvement compared to swilling with the placebo drink. In addition to power output being higher, lactate levels and heart rate were also higher."

It is also noted that the rider's perceived level of exertion did not change between the two time trials.

The researches of this experiment suggested that the differences between the time trials could be put down to the fact that carbohydrates were detected in the mouth, "which fooled the brain into thinking the rider had taken fuel on board". This would allow the brain to remove limitations on the muscles.

There is however, one problem with this conclusion. It is stated that the detection of carbohydrate in the mouth was the cause of improved performance, and that this must be the case as no carbohydrate was ingested. However, this conclusion makes no consideration for the fact that glucose is able to pass through membranes, and can therefore be absorbed into the bloodstream from the mouth. This would mean that in the 5 second period the athlete is swilling the sports drink, glucose is being absorbed which will provide energy to the working muscles. It is not possible though, to say how much glucose would be provided to the muscles as a result of this.

With this taken into consideration, it is clear that the experiment is not completely valid. However, as a concept it may have some validity. If we refer back to the piece i wrote about Caffeine as a supplement, it showed that it was the ability to change an athlete's perception of fatigue , rather than have a physiological effect is key to the way it works.

Rather than this experiment proving the "Central Governed" theory to be true or false, i feel it can provide a base to further experiments concerning this theory. I also believe it could be used as an opportunity to look further into this use of sports drinks, as some athletes suffer from bloating when drinking during exercise.




Ben Brown

Caffeine. A super-supplement?

The 2010 Ironman UK triathlon is fast approaching, and as athletes are making their final preparations, i thought it would be a good opportunity to consider the aspects that make up an optimal race day performance.

Amongst the plethora of factors which make up a good performance are obvious things such as getting the right amount of sleep, carbohydrate loading, allowing muscles to recover etc. However, in this blog we will consider the role that supplements can take in improving performance in endurance events, specifically Caffeine.

Caffeine has been widely accepted as a successful performance booster in short duration, maximal effort events that last up to 5 minutes. Caffeine is useful in events such as the 100m sprint because it increases alertness, facilitating a faster reaction time to the starting gun. Caffeine also has a physiological effect, lowering the threshold for muscle recruitment. This facilitates high power muscle contractions.

Both of these factors are beneficial to performance in sprint orientated events, however Caffeine is beneficial to endurance athletes as well, as it allows them to delay fatigue through reducing the athlete's perception of effort. Caffeine achieves this by releasing Beta Endorphins during exercise. These endorphins reduce the athlete's perception of pain and create a sense of well-being.

This is not the only way in which Caffeine aids performance however. A study undertaken by the University of Birmingham looked at the effect Caffeine has on exogenous carbohydrate oxidation (the rate at which carbohydrates consumed are burned).

The experiment involved 3 groups of cyclists taking part in a 2 hour indoor cycling test. Each group consumed a different drink.

Group 1 - 6% glucose solution
Group 2 - 6% glucose solution plus Caffeine
Group 3 - Plain water.

The study revealed that cyclists in group 2 had a rate of exogenous carbohydrate oxidation 26% higher than cyclists in group 1.

The conclusion drawn from this study was that Caffeine may increase the rate of glucose absorption in the intestine. This allows fuel to be provided to the muscles more quickly. This is especially important to triathletes competing in the Ironman competition, as high carb bars and gels can be absorbed faster.

This particular effect of Caffeine is likely to make it possible for athletes to work harder, for longer periods of time, whilst suffering less as a result of fatigue.

Caffeine is the world's most consumed pharmacological substance, most commonly found in tea and coffee. It is clear therefore that the substance isn't harmful when used in suitable quantities.

The suggested intake for an endurance athlete before an event is 5mg to every kg of body weight. This means a 70kg athlete would need to take on 350mg of Caffeine 45 minutes before the start of the event. 350mg of Caffeine is equivalent to about 3 cups of drip brewed coffee.

It is important to consider the possible harmful effects of using Caffeine as a supplement as well as the benefits it provides.

• May cause sleeping problems
• Can cause headaches
• Can cause diarrhoea
• Can lead to over-arousal in a sporting event

In my personal opinion i feel that the benefits an athlete will experience as a result of using Caffeine outweigh the negatives. However, it is absolutely necessary for an athlete to give Caffeine a "trial" run as a supplement during their preparation for an event such as the Ironman Triathlon, as this will allow them to ensure they are not prone to the harmful side-effects.



Ben Brown

The ever-growing grey area

With this years Tour de France underway, you could be forgiven for feeling as though something has been missing from the build up to the big event.
The build up to this years Tour has not seen any scandalous drug/doping busts, despite the allegations flying around as usual.
It is extremely sad that a drug free start to any major sporting event merits praise, and even worse that the weight of expectation suggests that the next positive tests are sure to be just around the corner.

However, to briefly stray onto the optimists side of thinking, it would appear that 2010 has the potential to be a step in the right direction for cycling to repair its torrid reputation.

I thought today's blog would be a good opportunity to consider Platelet Rich Plasma Therapy, a method which has recently found itself on WADA's Prohibited List.

PRP Therapy is a method remarkably similar to Blood Doping, however, the purpose is to aid recovery rather than increasing Cardiovascular performance.


This form of therapy uses Plasma, which makes up about 55% of the total blood volume. The Plasma itself consists of 90% water, with the remaining 10% being made up of Dissolved Proteins, Glucose, Clotting Factors, Mineral Ions, Hormones and Carbon Dioxide.

To separate Plasma from blood, there are a number of stages which must take place.

• Firstly, 30mls of blood is taken from the athlete.
• Next, the blood is separated into Plasma, White Blood Cells and Red Blood Cells through spinning with an anti-coagulant in a centrifuge.
• The Platelet Rich Plasma gained from this is then injected into the injured area of the athlete's body.

The Platelet Rich Plasma which has been injected into the injured area aids recovery by secreting Growth Factors. These Growth Factors stimulate tissue recovery, speeding up the rate at which an injury heals.

PRP is useful for injuries involving soft tissue, such as Tendons, Ligaments and Cartilage. Tiger Woods received 4 injections of PRP with the aim of improving the condition of his ACR Ligament more quickly, allowing him to make his comeback.

PRP therapy has been used by athletes for over 10 years now, however this year the method has entered the WADA prohibited list. This ban does not prohibit its use outright though. Section S2-6 of the 2010 WADA Code states PRP can be used by athletes, but only if injections involve joints or areas surrounding muscles. Direct injections into muscles can invoke a 2 year ban from competition.

This ban suggests that WADA have not come to a conclusion over the future of PRP use. I feel that they will have a difficult task in coming to the right conclusion.

Amongst the factors which support the legality of PRP, the strongest arguments are:

• Allows athletes to compete more, facilitating further achievements.
• Commercial benefits, as there is more competition to broadcast/sponsor/advertise etc.
• May allow athletes to pro-long their careers.
• Inexpensive technique, meaning the issue of keeping a level playing field is not a problem.

However, there are a number of negative factors which suggest this method should be banned outright:

• There are suggestions PRP therapy can be used as a mask for Human Growth Hormone injections.
• Could widen the gap between Amateur and Professional.
• Could be considered as taking away from the sport's traditions.
• May have a harmful effect on the reputation of the sport.

Personally, i feel that the correct decision would be to ban the use of PRP therapy completely. There are a number of contributing factors which lead me to this conclusion. The most important factor for me is the belief that unless the necessary morals of sport are maintained, then popularity of sport on a grass roots level will become diminished. This obviously makes the future of sport look fairly bleak. By ensuring future athletes are not alienated by the gap between amateur and professional, participation will increase, and in the future this will be evident in terms of an improved quality of competition.

Ben Brown

Why is Usain Bolt the world's fastest man?

The answer to this question is very likely to lead straight into a nature vs nurture argument.
It is very clear of course that a large amount of Usain Bolt's dominance in world sprinting events can be attributed to genetically inherited factors, such as a high proportion of Fast Twitch type 2b muscle fibres.
However, it is important to consider the other, Nurture aspects which have lead to Usain Bolt's success. It goes without saying that this athlete has undertaken a huge amount of specific training to improve his performance. This Blog will consider one of the training methods used by Usain Bolt which allowed him to develop his performance.


The method we will be considering is Plyometrics.

Plyometric training involves the use of jumping and hopping movements. The purpose of this training is to develop explosive power within particular muscle groups. Usain Bolt will use plyometrics to increase the power of his Quadricep, Hamstring and Gastrocnemius muscles.

Plyometric exercises are effective because they take advantage of the Stretch Shortening Cycle. The Stretch Shortening Cycle is the occurrence of an eccentric contraction, followed immediately by a concentric contraction.

We can use the Squat Jump as an example to explain how these contractions take place. The first movement is a jump into the air from a crouched position. This movement occurs due to a concentric contraction of the quadriceps, as this muscle group is shortening to cause the knee to extend.
The landing phase of the jump causes the quadriceps to perform an eccentric contraction, allowing the body to decelerate. Once the muscle has lengthened to a certain extent, the stretch reflex is initiated. This reflex is a protective measure, as it prevents the muscle from overstretching. The stretch reflex is important in Plyometrics as it not only stops the muscle from lengthening, but reverses the muscle contraction.
The Stretch Reflex therefore initiates the next phase of the Squat Jump (the next jump).


It should also be said that there are a number of problems with this form of training. The first of these is the high risk of injury associated with such intense training. The high impact landings can prove stressful to joints.
Plyometric exercises are also very likely to cause D.O.M.S (Delayed Onset Of Muscle Soreness). D.O.M.S is almost certain to occur 24-48 hours after the training session has taken place.

Both injuries and D.O.M.S can be reduced through use of proper Warm-ups/downs, Ice Baths, Massages and most importantly suitable Rest Periods.



Examples of Plyometric Exercises can be found here (http://www.sport-fitness-advisor.com/plyometricexercises.html)


Ben Brown