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Getting faster is easy. In theory part 2.
In the first blog on sprinting we spoke about acceleration performance. In this blog we will look at maximal speed sprinting. This is your ability to run at your fastest speed possible.
Luckily through the IAAF biomechanics research projects, we have some amazing data that shows what makes the best in the world run really fast. Ultimately with top speed, that is velocity in m/s is determined by two factors. Stride length multiplied by stride frequency. It seems simple but it is these items that then need to be broken down further. When we think about stride length it is ultimately influenced by two key factors. The height of the athlete (more specifically their leg lengths), and the ground reaction force that they apply to the ground. The research by Weyand and Clark highlights that ground reaction forces at top speed are as high as 5 times our body weight and occur in as little as 0.08 seconds. We add this to the information supplied by JB Morin and his group and we come to the conclusion that if you can hit the ground hard, rapidly and in the correct direction, you are likely to develop the necessary ground reaction forces to have a sufficient stride length. The forces that you see in the ground reaction force are a combination of muscular input and stored elastic energy created in the leg when you land with a stiff and stable leg and ankle. Measurement of elite performers at the 2017 world championships showed that stride lengths are typically between 1.3-1.35 x height in males and 1.25-1.3 times height in females.
Stride frequencies tend to vary once again on the height of the athlete, this is due to the balance between the stride length and stride frequency equation. If you have a very long stride length, such as Usain Bolt, you do not need an extremely high stride frequency, however shorter athletes will require much higher frequencies if they cannot create sufficient stride lengths to match taller athletes.
How do we do this?
The area that is always discussed in reference to stride frequency is the ability of the athlete to exchange their legs; this can be done in two ways. Actively, and actively with reflex assistance. Active exchange is the physical movement of their legs by the athlete, if it is completely conscious and driven by the muscular system alone, it is likely to be insufficient to achieve world class frequencies (as high as 5 steps per second). The use of the cross extensor reflex (the reflex that occurs when we quickly pull up or push down our leg) causes the opposite limb to reactive reflexively, allowing athletes to use their neurological system to evoke a reflex, reduces reliance on muscular structures and aids with the speed at which we can exchange our limbs.
So how do we run faster?
As suggested in theory we need to hit the ground hard, on a stable/stiff leg, very rapidly and in the right direction, whilst switching our legs reflexively. It sounds complicated, and that is why running faster requires significant practice. To assist in this process using technical drills such as dribbles (cyclical running that aids with ground contact stiffness and switching), and running over mini hurdles or cones (allowing for manipulation of stride length and frequency) can be useful. Obviously exposure to maximal sprinting repetitions will assist with practice then if required the use of assistance (downhill, wind or pulley system) all allow the athlete to learn to move themselves across the ground faster.
We hope you enjoyed this blog series. If it was of interest to you we will be running a sprint mechanics workshop on April 14th. To book your place register here.
Understanding of what allows people to run fast and potentially what will allow them to continue to get faster is continually emerging. In this two part series, we will look at how to accelerate faster and how to hit a higher top speed.
It is important to highlight that the different phases of sprinting present some unique interventions and understandings. Acceleration, that is the initiation of running up to a top speed, is the first part of any running action and is present in most athletic pursuits that involve running.
Because of its application to team sports, acceleration abilities have continued to receive the greatest volume of research attention. Multiple studies, a number of which have been led by JB Morin, have looked at how athletes accelerate. These indicate that the athletes that can produce high levels of resultant horizontal impulses at high velocities as their foot hits the ground tend to be faster accelerators. What does that mean? It means if you can push yourself forward forcefully (at a high rate of force application) and move your limbs quickly to push into the ground it is likely that you will accelerate at a faster rate.
How do we train this?
As suggested researchers such as JB Morin have been leading the way along with his colleague Pierre Samozino, they have been looking at simple ways to teach athletes to achieve higher resultant horizontal impulses and have used the application of high load sled running. These loads have been higher than the traditional use of sleds, up to weights equivalent to 100% of the user’s body mass.
What have they found?
Using heavy sleds teaches people to apply greater proportional horizontal force to the ground in the initial acceleration and is showing promising application to both team and individual sport athletes. Essentially it is teaching athletes to push in the right direction and as long as they are coached to do this with fast contacts then they are learning to accelerate themselves to faster speeds. In a practical way this can be achieved through any method that teaches the athlete to propel themselves forward quickly, in the forward direction and with a rapid and aggressive contact with the ground (high net horizontal impulse). This can be achieved through any form of resisted sprinting (hills, sleds, pulleys), and also without resistance. The key is to practice the aggressive propulsion of both the body and the limbs as they contact the ground.
In the second blog we will look at how we can improve maximal velocity sprinting.
What a pain in the groin!
Groin pain and injuries are a nuisance. They are often caused by multiple factors and can be difficult to assess, diagnose and treat effectively. So when I read a recent paper looking at reducing groin injuries in sport I thought it would be good to discuss the potential contributing factors the development of groin injuries and some potential solutions that are starting to be discussed.
Typically groin injuries fall into a few categories. There are the sudden onset injuries (strains) and the insidious development injuries (tendinopathy, pubic symphysis overload etc). These insidious injuries are generally considered overuse injuries and represent up to 80% of all hip and groin complaints, Moore and Young 2010. Work by Falvey et al 2009 described the groin triangle suggesting that the anatomical site of the pain is important to describe the treatment progressions. They identified that typically groin pain is associated with the adductor tendons and attachment, the rectus abdominis (the abdominals and associated attachment), the ligaments of the pelvis or the pubic symphysis. These descriptions are helpful, however they go onto discuss the biomechanical overload nature of groin injuries and how address the anatomical site alone may lead to insufficient rehabilitation.
So what do we need to assess and then treat when someone has groin pain?
The Moore paper identifies that musculoskeletal imbalances (weak and tight hip, groin, lumbar and thigh musculature), poor skill execution, fatigue, incomplete rehabilitation, repeated trauma and inappropriate training/competition loads can all contribute to the development of groin pain and injuries. With so many factors involved where should we start?
The first thing to identify is always the aggravating factors, the site of the pain, the associated capacities of the tissue (strength measures, range measures) and then look to place this within the context of that athletes training and competition schedule. If they are weak, have poor hip and groin range and are training in a sport that requires great capacity through the groin over a repeated training or competition season, then it is a straightforward process to start to address these factors. The more complex part of the rehabilitation is often working with the sport specific coaches to identify the biomechanical skill factors that contribute to groin loading and then aim to correct faults whilst increasing the load of skill training. The difficult part of overuse groin injuries is that they can take significant time to work on all factors and therefore can be a length process.
So how do we potentially reduce the incidence of groin injuries in the first place?
A recent study in Norwegian semi pro soccer players show that basic implementation of groin strength exercises reduces groin injury complaints by up to 40% across a soccer season, Haroy et al 2018. With this in mind addressing the adductor strength capacity as well as maintaining joint and tissue range around the hip is likely to lead to a significant reduction in the incidence of injuries in sporting populations such as soccer. This is obviously only a few factors, however it does highlight that basic implementations of training to address capacities such as strength are effective in groin injuries and are a great place to start if you are working with a sporting team.
Is stretching valuable for athletic performance?
We deal with a high proportion of track and field athletes as patients in our clinic. Sprinters, jumpers and throwers all have common attributes – good discipline, and more interestingly high level of body awareness. It makes sense, these are athletes who generally have a short window to perform and extremely demanding endeavour so the importance of assessing your body and mind in warm-up routines is a paramount component for performance and injury risk. It never ceases to amaze me the number of these athletes that come into the clinic and are quick to state something along the lines of “my body is so stiff” or “I know I should do more stretching” whenever the conversation or assessment of flexibility comes up. It should be mentioned that these statements always carry a negative association, whereby this known deficit is having a decremental effect on performance. This raises an important question – if you believe you are stiff and this is having a negative effect, why are you not implementing interventions into your training to either reverse or mitigate these effects?
This is the consequence of a larger issue at hand, that is there is a lot of debate and discrepancy about whether stretching has any therapeutic value or benefit to athletic performance. This extends from researchers to clinicians and coaches. Herein lies one of the major issues related to stretching, an individual may have experienced a positive effect from stretching whether it be related to freedom of movement, enhancing recovery or mitigating the effects from training (e.g. DOMS or muscle soreness) however it has not carried over to implementing it into warm-ups, cool downs or as a training session in itself. This is often due to influential powers, coach or health clinicians, believing stretching may not be of benefit.
Why might this be the case?
Over the course of the late 90’s and and early 2000’s, a number of research studies, most of which were completed on untrained individuals, applied stretching acutely and showed a reduction in power output for tasks such as jump performance. This may sound bad, however if you have never been exposed to an intervention, then it is a likely outcome that your body will respond poorly to it initially. Imagine we were to give heavy squats to an untrained individual and then asked to measure jump performance. Of course it would be bad, however we know from ongoing research that particularly in strength trained individuals squatting prior to jump performance may actually boost jumping performance, and long term exposure is very likely to enhance jump performance over the long term. A more recent review, Behm et al 2016, shows that if applied over a period of time protocols of stretching not only enhance performance acutely but reduce the risk of injury, this is in both static and dynamic applications of stretching. Pinto et al showed that the previous reductions in performance from static stretching may be associated with the duration >60 second holds, however 30 second holds enhanced or had a nil effect on performance, but reduced injury risk.
So again the question is ‘Is stretching valuable for athletic performance?’ I purposely structured the question this way to highlight what I consider an important point – such questions invoke dichotomous thinking, but this black and white logic is just illusory. The truth is there are many factors that need to be considered with regard to stretching, as discussed by Behm et al, but we do know that if applied well it can improve range of motion, reduce injury and potentially improve performance at no detriment to power output. We will look to discuss many of the factors further in future posts.
Minimal, cushioning, barefoot? Maybe it doesn’t matter.
The last 10 years have seen the barefoot and minimalist running revolution come and maybe even go, however it is a question that I get daily from patients. What kind of shoes should I wear? And how should I run to minimise the impact on the ground, should it be a heel strike, midfoot or something in between?
The study that pushed people to question this was the work by Lieberman in 2010 Nature paper that suggested that impact forces were lower with barefoot running compared to wearing shoes. This seemed to spark the revolution, however consistently since that time researchers and clinicians alike have been looking at the multitude of other factors that go into what makes up running ground impact forces, how technique adjusts with different footwear and the overall effect of running conditions.
More recent work by Udofa et al 2019 using the techniques developed by Ken Clark and Peter Weyand starts to look at the effect of different footwear and how impact forces are created and also adjusted by different footwear. Interestingly loading is similar in each condition, the main difference is that people will alter the angle or point of contact with the ground if they are wearing shoes or not. So typically wearing shoes the runners are happy to put their heel onto the ground and have a higher loading rate, which is the speed at which the force is created (this sounds bad but is probably not, I will explain shortly) whereas the barefoot runners will place the midfoot onto the ground and absorb the forces through the calf and achilles to reduce the loading rate that the impact force creates. The interpretation by a number of researchers and clinicians is often that this reduction in loading rate is a good thing, the rationale being less is better. But our friends from physics will tell us that the first law of thermodynamics is that energy is neither created or destroyed, it is just transferred.
Why is this important?
The energy or forces that occur when landing do not disappear based on where you put your foot down onto the ground or what shoes you are wearing. They just transfer to other areas of the body. This means that you can try and manipulate the landing position of the foot but you will always have to deal with the forces somewhere. In the barefoot example, your calf and achilles absorb the forces, so if you are getting knee pain due to landing on your heel on the ground, the solution of running barefoot or landing through the midfoot is robbing Peter to pay Paul. You may get less knee pain, however you may develop achilles or calf problems due to the compensation that occurs on landing.
So what is the solution?
Particularly if you are not sprinting (distance running), the best solution is to adopt a running pattern that creates an even distribution of forces through the foot, ankle, knee and hip. The best way to do this is to land on a full foot strike (greatest base of support) and keep the landing under the hip as much as possible (close to the center of mass of your body). This allows you to ustilise each joint and surrounding muscle and connective tissue to their greatest capacity and allows you to use the biomechanical advantages (levers etc) to distribute forces evenly, as we said the forces will always be there, you get to choose which joints and muscles need to deal with them. Now you can also manipulate step length and frequency, which we will not get into now, however particularly increasing step rate will allow you to land under your centre of mass easier and thus assist with this force distribution.
So does it matter whether you wear shoes or not? Probably not, the best solution is to learn to run in a way that maximises your body’s capabilities to distribute forces and push you forward.
Same injury. Different athletes. Different rehabilitation?
Athlete profiles and injury rehabilitation
I recently had a conversation with one of the physiotherapists in the clinic about tailoring rehabilitation to type of athlete. Athlete profiling has become more popular in recent sports science research. In particular the work of JB Morin and his team have started to highlight that in running and jumping athletes the force-velocity profile of the athlete can be relatively easy to calculate. What this means is that the way in which somebody creates movement is usually related to the use of a force strategy (using strength and force application) or velocity strategy (increased limb or segment movement speed). Obviously there are athletes that are good at both, so it is important to look at the profile as a spectrum rather than as being in one camp or the other. The conversation ventured into sports that were hybrids such as team sports or even aerobic in nature. With these sports the profile looks at the type of athlete and what makes them successful. An example could be a midfielder in Australian rules football. The profile of these athletes can be vastly different, some are explosive, strong, able to create clearances, but may lack the aerobic tank to spend the whole game in the midfield. Others are the run all day midfielders that utilise aerobic conditioning to outwork their opponents.
Understanding these profiles in sport has a big effect on why an athlete may develop an injury and how we must address the injury. If we use the example of the two players described in AFL, if they were both to sustain a hamstring strain (grade 1, musculotendinous junction, biceps femoris) the reason for the injury may be very different.
Let’s make some assumptions and work through the scenario.
The explosive player is likely to be physically powerful, faster and have good jumping and off field gym strength, including hamstring strength. The aerobic engine athlete is likely to have high playing and training capacities, have reasonable speed, but better at speed endurance and repeat running efforts, have adequate strength for the sport but not be a beast in the gym.
So what would this mean for their injury development. More than likely the explosive athlete does not lack strength, they are mostly likely to develop a hamstring injury due to fatigue, too much high load game or training exposure, or potentially poor running mechanics. The aerobic athlete is unlikely to have a fatigue related hamstring strain, but more likely to lack high strength, particularly when at high speeds, for example when sprinting for a ball for example. Again we cannot discount running mechanics, however for this example, let us say they both run adequately well. So the development of the same injury is caused by completely different scenarios.
So should the rehabilitation be the same? Probably not.
With the first athlete, the rehabilitation should address the underlying tissue damage and expose them to graduated training and game play, however in order to reduce the risk of reinjury, a large focus should be placed on increasing conditioning of the athlete and then a strict use game day rotation system to reduce likelihood of getting to a significantly fatigued state, is likely to have a better effect than the common protocol of strengthen the hamstrings even further.
With the aerobic athlete the rehabilitation may be significantly focused on increasing overall strength capabilities as well as hamstring strength and velocity producing capabilities so that future exposure do not contribute to reinjury.
As you can see understanding the athlete profile has significant influence on why they develop injury and how you need to manage return to sport and future injury risk.
Are athletes healthy?
Recently I found myself in a commercial gym for the first time in a few years. Given our association with athletes in the work that we do, I could not help but look at what some of the gym attendees were doing. At one stage of the session I noticed what I presume was an athlete who participates in powerlifting, they were squatting at one of the squat racks and gradually piling on the weights. There were two things that I noticed. The first was that they were extremely strong, gradually increasing the numbers on the bar to what looked a minimum of two times bodyweight. The second was that they were gulping down large cans of energy drinks and a thought came to my mind; although they were strong, they were certainly carrying a significant amount of non functional mass (adipose tissue) and that the energy drinks surely was not the best option for health. Which brought to mind, are we destroying our health to be good at sport?
This topic has been discussed previously and an interesting article was published by Maffetone and Laursen in 2016, that highlights this very idea. Being fit for sport, does not guarantee health. The article identifies that there are often context specific dynamics at play in relation to certain sports, which bring with it behaviours related to food, training intensity, recovery and injury. Having worked in sports such as rowing and running, athletes will often overtrain at the expense of health or injury, as it is a commonly held notion that high training volumes or intensities are to be expected and injury and illness are necessary hurdles in the pursuit of excellence in those sports. Secondary to this, the article highlights that there are often contradictory behaviours associated regarding food in these sports. In rowing the pursuit of high volume training necessitates high calorie consumption, and I have discussed with some of these athletes the type of nutrition associated with this type of training. Some of the athletes have shared that they would routinely eat a whole loaf of bread each day with nutella or peanut butter during heavy training periods. Neither of these foods in moderation may be bad, but consistently eating nutella sandwiches does not scream healthy eating habits. The other side of this is runners, particularly distance runners, significantly under eating to keep their body mass down. This is obviously a terrible idea for someone completing significant training and is likely to reduce the long term training adaptation and health.
For those interested the article by Maffetone outlines how the mechanisms of the body relating to high volume or intensity training and poor food choices can lead to significant health effects. These may be short term or accumulate to lead to long term health issues. It appears that often the biggest driver of these behaviours is a rush to achieve results prematurely without adequate progression. With this in mind it is certainly possible to achieve elite performance and maintain health, however it does take adequate planning from the athlete and all of the associated support staff (coach, medical, nutrition, strength and conditioning) to get the balance right.
Decision making and opportunity cost.
Opportunity cost is not typically spoken about when it comes to injuries. Classically it is referred to in the business, financial or investment fields. It refers to the loss of alternatives by committing to one alternative or option. This may not seem like something that affects injury management, however after reviewing the previous two blog posts it made me think that we as health professionals consciously choose an option when carrying out a rehabilitation plan. We select which type of exercise to prescribe for a patient with back pain and we choose when to initiate the rehabilitation following the onset of an injury. Patients decide when to seek out assessment and treatment and even who they get to complete the assessment and treatment. In this way both practitioner and patient effectively commits to an alternative and therefore loses the other possible alternatives. Even if they seek a second opinion they may have incurred an opportunity cost of time and money in selecting the first alternative.
This may seem trivial but as stated in the previous blog post on muscle strain injuries, if a practitioner advises a patient to start rehabilitation one week post injury they have lost the opportunity to make improvements that ultimately have been shown to reduce the time to return to sport.
From the patient perspective commonly held beliefs may influence them to seek out treatment after a certain period of time. Common ideas include the notion that you cannot start rehabilitation on a muscle strain if you still have pain. This presents a clear opportunity cost that many people may not be aware of.
The post on pilates highlights that by choosing a modality, method or technique we may be limiting other alternatives or approaches. This happens often when a patient may be informed that surgery is the primary option, when often conservative management presents similar if not better outcomes for these injuries. These examples highlight that by being conscious of the decision that we are making we may be able to select the most appropriate alternative, rather than the easiest, most accessible or simplest option.
This type of opportunity cost is not only limited to rehabilitation and injuries. As some of you may know, MAD is also heavily involved in sports performance, conditioning and coaching. The idea of opportunity cost in this arena is highly important also. Any coach or athlete across sports needs to be aware that by committing to a training plan or exercise scheme they are consciously selecting an alternative that may diminish or remove the opportunity to use another alternative. If it is the most beneficial option at that time it will lead to the biggest benefit, however if it is a minimally beneficial option it may lead to a period of non improvement and a significant opportunity cost of time.
This post is not to cause people to spend extended amounts of time researching every last option before selecting an alternative, but rather giving awareness to the decisions we make for patients we treat or the athletes we coach. Identifying that every action we take presents an opportunity, we must aim for it to be maximally effective, whether in isolation or in a multi-modal approach, so that we do not lose further opportunities due to that decision. The questions to ask ourselves include is this the best option? Are there other alternatives that may assist with achieving the best outcome if combined with this option? Is this the best time to implement this option? Will implementing this option eliminate my opportunity to utilise another alternative in the future? If you can answer those questions with some confidence then the decision becomes easier to make. It will never eliminate opportunity cost as that is impossible, but it will provide some clarity in our decision making process.
Melbourne Athletic Development Discussion
Women's Football with Zach Nelson (Rehabilitation Co-ordinator at Western Bulldogs Women's AFL)
Podcast with Jack Williams - Yoga and flexibility. A brief discussion on how it fits into sports performance and injury management
Podcast 7 - Discussion with Jeremy Weeks on running mechanics
Philo Saunders Article
Podcast 4 : Melbourne Athletic Development at the Altis Performance Therapy Program - Day 2
Podcast 3 : Melbourne Athletic Development at the Altis Performance Therapy Program
Podcast 2: Hamstring injury discussion with Physiotherapist Zach Nelson
Works by David Opar
Training load discussion by Tim Gabbett
Some fantastic insights into training and running mechanics can be found at Altis World Twitter
Podcast 1: Discussion with Cody Williamson (Physio, lecturer, strength coach) regarding paediatric resistance training. C.Williamson@latrobe.edu.au
Podcast 1: Discussion with Cody Williamson (Physio, lecturer, strength coach) regarding paediatric resistance training. C.Williamson@latrobe.edu.au
For information on accreditation courses discussed please see:
ASCA accreditation (also though the APA as well)