Sport Science

Variability in Human Movement – Thinking Outside the Box

by Matt Jordan on May 17, 2012 No comments

As you may have noticed, my blogging rate has diminished this week.  It’s not that I haven’t been thinking about blogging.  It’s been on my mind a lot but I’ve had a hard time thinking about how to approach the article you are about to read (note – I’ve included some practical coach’s tips to help you apply some of the concepts).  I had to remind myself several times of my goals and mission.

Goal #1 is to provide credible, honest and unbiased information on health, fitness and performance.  I think we all need to be prudent about those who spread mistruth for financial gain, and unfortunately this is quite common in the fitness industry. I think it’s important to have a source to turn to for some truth especially when it comes to your health and fitness goals, and hopefully I can be a part of this process; Goal #2 is to teach you how to think like a sport scientist so that you can become the expert.  From my experience, the more an athlete or client knows the better equipped they are to overcome challenges, and to adapt their training to meet the new fitness and health goals that emerge over the lifespan.  It’s like the old adage “give me a fish and I eat for a day, teach me to fish and I eat for a lifetime”. 

A big part of this is learning how to assess the relevance of information and data.  Just because a scientific study finds something novel or interesting doesn’t make it a truth, and furthermore there are many different ways to analyze and assess data from the natural world.  For example, I’m a big proponent of individualizing the training and nutrition process.  I described one way of approaching this in a previous blog on the responder-factor, which generated a lot of interest with those who have been following my blog.  Briefly, the responder-factor involves the clustering of individuals in a population into an extreme-responder, responder, and non-responder group.  As the science around genetic testing emerges, I can guarantee you this will be a major consideration for health professionals because it is becoming increasingly evident that our genetic makeup greatly affects whether or not a particular medical treatment will be effective.

Responder Factor

Coach’s Tip

In addition to the responder-factor, I think another tendency in assessing data is to focus solely on whether or not a particular variable improved in response to a treatment.  Take vertical jump for example.  As I mentioned in a previous blog, vertical jump is often considered as a performance measure.  Often a coach or trainer will evaluate the effectiveness of a training method for improving vertical jump and may find that vertical jump decreased so they will conclude the method was ineffective.  However, vertical jump is very sensitive to fatigue and tends to have considerable variability over a training cycle, and a depression in vertical jump may actually reveal that a training method is working!  In fact, evaluating the variability of vertical jump over a training cycle can provide tremendous information to the coach or sport scientist for peaking strategies and for evaluating an athlete’s adaptive potential.

Vertical Jump

Coach’s Tip

Variability is a significant part of the natural world, and can often be an indicator for health or peak physiological function. For example, it has been shown that elite pistol shooters display considerably better end point stability (i.e. gun control) than novices; however, the elite shooters display considerably more variability in muscle activation compared to the novices.  It has also been shown that individuals with patello-femoral pain syndrome and lower back pain exhibit considerably less variability in muscle activation compared to their healthy counterparts.  I went into great detail in my blog from Day 4 at the ECSS Conference, and you can hear Matt Price and I discussing the importance of this for elite sport in our powercast available on iTunes.

In my recent presentation on the Quotidian Movement Screen (QMS), I also discussed how an athlete’s quality of movement is highly variable and sensitive to training stress.  Our group at the Canadian Sport Centre-Calgary integrates the QMS movement screen into our daily routine, and we use it to properly prescribe activation and mobilization exercise.  It adds a further layer into our assessment of an athlete’s adaptive potential.  In this instance movement screening is not seen as a “pass/fail” test as it is in so many movement screens but instead is assessed with an expectation that movement will change in response to training stress, and that detecting this change is a critical part of the training process.

Coach’s Tip

Looking for trends in the normal variability that can be observed in the natural world can be complex but it’s applications are seemingly endless.  A great example of this is the science of Fractal Analysis, which was pioneered by a famous mathematician named Benoit Mandelbrot.  Mandelbrot expanded on his observation that many physiological processes and aspects of the natural world with seemingly chaotic patterns could actually be described mathematically.  In simple terms, an object with a fractal dimension has an element of self-similarity from a large scale down to a small scale.  Consider a small branch of a branch on a tree in a forest.  Upon first glance, the little branch appears to be nothing more than a random set of bifurcations but when examined with respect to a fractal dimension, not only is this branching pattern similar for the entire tree but also for the surrounding area around the tree.  This gives ecologists a tremendous advantage because by studying the branching that occurs on a small scale, which is relatively easy, it tells them about what is happening on a much larger scale in the forest, which is relatively hard to do (for more information on this, check out the PBS Series Nova, and the episode on Fractals, Hunting the Hidden Dimension).

The self similarity in branching of a tree is also paralleled in the human body where the branching of blood vessels and capillary network in organs has been shown to have a fractal dimension (Figure 1).  Interestingly, if a cancerous tumour is present, the tissue loses this fractal dimension, which gives physicians a powerful tool for detecting cancer.

Figure 1. Representation of the fractal dimension, and the application to human physiology [From: Glenny et al., (1991). Applications of Fractal Analysis to Physiology. J App Phys]

In addition to blood flow, many other physiological variables possess a fractal dimension.  For example, heart rate displays considerable variability, and the analysis of heart rate variability (HRV) can help detect morbidity, and even overtraining and overreaching in elite athletes.  Postural sway also has a fractal dimension.  To get a picture of postural sway, stand up and close your eyes.  You will notice that you don’t stand still, instead there is a gentle sway in your position.  If you were to stand on a force plate and measure this sway, you would obtain a very random looking pattern (Figure 2).  Interestingly, individuals who have sustained a concussion lose this fractal dimension, making the analysis of postural sway of interest to those returning from concussive injury.

Figure 2. Postural sway measured on a force plate.  Analysis of this sway reveals a fractal dimension, meaning there is self-similarity across multiple scales of magnitude [From: Duarte & Zatsiorsky (2000). On the Fractal Properties of Human Standing. Neuroscience Letters]

In summary, it’s important to understand how to look at data regardless of your level of fitness or performance.  Let’s face it, we are bombarded with all sorts of information on a daily basis and making educated decisions for ourselves is key.  Finally, remember that the variability that occurs in our seemingly chaotic and random world can actually have great meaning, and can provide us with tremendous insight into the adaptive process.

www.jordanstrength.com

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Matt JordanVariability in Human Movement – Thinking Outside the Box

10 Lessons in Vibration Training

by Matt Jordan on May 17, 2012 No comments

Over the past few years, I have received a lot of questions about vibration training.  For those of you who are new to vibration training, it involves the use of mechanical vibration to stimulate the neuromuscular system.  Researchers of vibration training have shown benefits on strength, power, vertical jump height flexibility, balance and muscle soreness (Cochrane, 2011).

My journey into the world of vibration training started when I studied the effects of whole-body vibration on muscle function for my Master’s Thesis (Jordan et al., 2010).  As with most graduate students, I started off a little lost and totally unsure about what I was going to study.  All this changed one afternoon when two of my most significant mentors and advisors on my thesis committee, Dr. Dave Smith and Dr. Steve Norris, approached me about a presentation they had just seen.  Joachim Mester from the German Sport University in Cologne presented some unbelievable results on the effects of vibration on muscle strength in an elite skier.  Needless to say they were very enthused, and encouraged me to pursue my research in the area of vibration training.

I knew absolutely nothing about vibration training so I began reading as much as I could.  I came across three papers published by a group out of Israel who had also found impressive gains in strength and flexibility after vibration training, and by a completely strange coincidence, I found out that one of these guys happened to be at the University of Calgary for his sabbatical.  I couldn’t believe my luck, and when I sat down with this guy I expected him to tell me I had found the holy grail of training methods.  I was shocked that instead of enthusiasm, he spoke with extreme caution and skepticism about vibration training.  As I sat there in disbelief, he carefully went down the long list of very well known health risks of vibration exposure, which include everything from detached retinas, to motion sickness, to debilitating nerve and blood vessel disorders (Griffin, 1996; Handbook of Human Vibration).  This led me to lesson #1 about vibration training: the risks of vibration training, if used improperly, could be significant.

He definitely took the wind out of my sails but after some further thought, I decided to take a trip to Europe to visit Dr. Mester and one of his former PhD students in Munich.  They took me to several training centres where vibration training was being used extensively, and once again, while some of the results had been staggering, they also expressed concern about the potential risks for vibration training.   I experienced this firsthand when they threw me on a vibration leg press and had me perform a few repetitions.  It was one of the most intense exercises I had ever done, and at the risk of hyperbole, it literally felt like someone had taken a jack hammer to my spine.  As I researched more about why I found this such an intense movement I started to learn the complexity in the response of muscle to vibration, and that vibration could possibly cause the re-recruitment of acutely fatigued motor units.  To put this into layman’s terms, this could allow you to potentially work beyond your normal capabilities, which on the one hand could lead to a substantial training effect but on the other hand could push you to the edge of the injury precipice.  So, lesson #2 about vibration training was that intense resistance training, combined with vibration, represents a substantial and intense training loadSubsequent scientific research confirms that vibration training can in fact lead to the re-recruitment of previously fatigued fast-twitch motor units (McBride et al., 2004).  Despite the possible contraindications, I think the use of vibration training in this manner is very intriguing, and is definitely on my research radar.

After my trip to Germany, despite the somewhat mixed opinions on vibration training my advisors and I made the decision that there was too much potential with vibration training to ignore it. By the fall of 2000, I had what I believe was Canada’s first whole-body vibration platform.  It arrived from Italy, and after ripping open the packaging I stood there a bit dumbfounded deciding where to start.  To start the process of understanding this training method, I decided to do what most responsible strength coaches would do and I got my other strength coach buddies to stand on it to see what would happen.

Stu McMillan, a long time friend and great strength coach was the first guy to experience some adverse effects.  Against my subtle warnings, Stu cranked the machine up to 60 Hz, which was the maximum intensity, and stood on the platform for one-minute.  He didn’t look overly good when he stepped off the platform.  His ears were ringing, and he had some pretty wicked vertigo, which passed after a short time.  The rest of us who were experimenting with the platform were responding without issue, and some of us were even feeling pretty good after we stepped off.  We all learned our third lesson: the frequency of vibration along with parameters such as the duration of exposure, amplitude, and what you do during vibration training are critical, and more is definitely not better (Jordan et al., 2005).

About two weeks later, after nothing but smooth sailing in terms of negative reactions to the platform, another friend of mine Andre Benoit, who is also a fantastic strength coach, noticed that if he relaxed his muscles while standing on the platform the vibration wave would travel up his body, and when he contracted his muscles the vibration wave would travel back down his body.  This was my fourth lesson that muscle dampens vibration, and incidentally, this is one mechanism leading to increased muscle activity during vibration training.

The fifth lesson happened about 10-seconds later, and this was when Andre’s body went into complete full-body resonance.  I’ve never seen someone shake like this in my life.  He stepped off the plate, and just like Stu, he didn’t look or feel very good at all.  Contrary to Stu’s symptoms, Andre complained of some serious gastrointestinal upset that persisted for a couple of days.  The fifth lesson was that the internal organs and many other systems such as the eyes and inner ear are very sensitive to vibration, and that standing on the platform in relaxed postures that limit the muscles’ ability to dampen vibration can be a really bad idea.

As I completed my Masters research my understanding of vibration training increased dramatically.  I was evaluating the effects of vibration on the ability of subjects to activate their muscles, and I was fortunate that all of my subjects were ex-athletes who could give me a maximal effort.  When I went back to analyze my data, one thing stood out: there were responders, non-responders and extreme responders.  In order to get my data published I looked at mean changes for the group but the responder-factor always stood out in my mind.  Here is lesson #6: there is great inter-individual differences in the response to vibration.  This was confirmed for me years after completing my Masters when I had a chat with expert track and field coach Dan Pfaff, and he told me about observing very explosive and fast twitch athletes who had lost “feel” after vibration exposure.

During the early years, I focused on using vibration to improve muscle strength and power, and as I experimented with its use, I refined my approach to use vibration in combination with plyometric or elastic strength development.  It was interesting to note that certain athletes had disrupted movement patterns, and as I referred back to the scientific research to explain the findings, I came up with lesson #7: the proprioceptive system, which includes length and tension receptors, pain receptors, and receptors that detect touch and vibration, is very very sensitive and responsive to vibration.  This is interesting because the proprioceptive system is heavily involved in regulating physiological responses like pain, the passive stiffness of connective tissue, flexibility, and balance.

Indeed, if you turn to the scientific literature, vibration training has been shown to affect all of the above mentioned responses.  A few of the more significant studies in this area is one demonstrating a significant improvement in flexibility in trained gymnasts (Sands et al., 2006), and that others that show decreased muscle soreness following intense eccentric exercise (Bakhitiary et al., 2006; Broadbent et al., 2008).  Interestingly, Broadbent et al., 2008 found that vibration also affected the biochemical inflammatory response following intense exercise demonstrating that vibration exerts its effects across many different physiological systems.  Lesson #8 and #9 are that vibration training is a great tool in warm up for acutely improving range of motion and flexibility, and it can be used very effectively as a recovery modality.

The broad range of vibration on the human body highlights the potential usefulness for vibration training with other populations such as the general public and those who are unable to exercise with high intensity but here’s a caveat: vibration training by itself is certainly never going to replace hard work and good nutrition for improving fitness and strength.  However, vibration training may be useful for offsetting age related bone loss in older populations and for improving strength, power and balance, which can reduce the risk of slips, trips and falls (Verschueren, 2004).  Lesson #10 is that vibration training may be a great training method for those populations who are unable to engage in regular physical activity; however, it won’t change your body into that of a Greek God.

So to summarize, I’m definitely a big believer in vibration training.  While the scientific research remains equivocal as it does with lots of novel training methods, I really do believe there is value to be found in vibration training.  My top uses for vibration training would be:

  1. To enhance recovery following intense exercise that may result in excessive muscle soreness.
  2. To increase the training effect from resistance training in well-trained athletes by superimposing vibration during regular resistance training exercises.
  3. To improve flexibility and range of motion.
  4. To acutely improve strength and power when used in combination with plyometric training or explosive resistance training.
  5. To improve muscle activation and eccentric force production when vibration training is used prior to exercise.
  6. To improve strength, power, balance and bone density in older populations who are limited in their ability to engage in regular exercise.
  7. To condition athletes who encounter large vibration loads in their sport (e.g. alpine skiers) when they are in a return to sport stage after injury.  My good buddy Matt Price, strength and conditioning coach with Alpine Canada, and I have used this a lot with our skiers over the years (www.meridian-ad.ca).

If you are interested in more information, stay tuned to my website as I will be releasing a video and Ebook on Vibration Training for athletes.

www.jordanstrength.com

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Matt Jordan10 Lessons in Vibration Training