Month: November 2013

Optimal Movement: Structural Adaptations Are Not Just A Hockey Problem

If you’re reading this from the U.S., I hope you and your family enjoyed a Happy Thanksgiving yesterday! I’m still fighting off a pie coma, but was able to get some writing done earlier in the week so the day wouldn’t be a complete loss. Enjoy!

Over the last several years, I’ve written a lot about the importance of assessing athletes and integrating corrective work into their training programs. More recently, I’ve discussed some of the principles of PRI, especially as they pertain to predictable asymmetries in the hips of hockey players. If you only read what I’ve written about these topics, it’s likely you have a very skewed understanding of what actually goes on at our facility.

Today’s article will be the first in a series that dives deeper into my training philosophy, and more importantly, the systems we’ve put in place to ensure our athletes are making progress on the full spectrum of athleticism.

Structural Adaptations: Not Just a Hockey Problem

Several months ago, I wrote an article highlighting the results of several research studies published in the last few years (See: Groundbreaking Research on Hockey Hip Injuries. More specifically:

A 2011 study from Silvis et al. found that 77% of the 39 NCAA D1 and pro hockey players had abnormal hip/groin MRI findings that were indicative of pathology, despite being entirely asymptomatic.
A 2012 study from Birmingham et al. linked FAI (a bony overgrowth at femoral head/neck and/or acetabular hood) to increased motion at the pubic-symphysis, a precursor to osteitis pubis and potentially sports hernias.
A 2013 study from Philippon et al. demonstrated that by the time youth hockey players reach the Midget age level (16-19 y/o), 93% of players have overgrowths consistent with FAI and 93% have labral tears.
A 2013 study from Jakoi et al. found that NHL players were less productive in the 2 years following sports hernia surgery than they were prior to the surgery.

Because of the title, you may have glossed over another important statistic:

A 2013 study from Larson et al. found that 90% of the 125 NFL prospects currently competing at the college level they looked at and 87% of the hips had findings consistent with FAI. Of these players, those with symptoms tended to have a greater prevalence of CAM or Mixed FAI and osteitis pubis, but the only independent predictor of groin pain was how much bony overgrowth their was.

Other evidence from Hack et al. (2010) suggests that roughly 1 out of every 4 asymptomatic men in the general population will also have some degree of FAI. Switching joints, a now nearly 20 year old study from Jensen et. al (1994), found that 64% of the 98 asymptomatic people that underwent an MRI of their lumbar region had abnormal findings. A 2002 study from Miniaci et al. found that 79% of the 28 asymptomatic shoulders of pro baseball pitchers had labral abnormalities.

Anecdotally, hockey players are more likely to possess a structural change known as hip retroversion, which essentially allows them more hip external rotation and less hip internal rotation. This is likely an adaptation resulting from skating a lot during the developmental years. Similarly, baseball pitchers (and all athletes that throw at a fairly high volume during adolescence) are likely to have some degree of humeral retroversion, a posterior torsion of the humerus that allows for more external rotation at the joint.

This is a demonstration of femoral anteversion, but is still useful in illustrating how the angle at which a bone inserts at one joint (look at the femoral head angles here) can have a profound influence on the position of an adjacent joint (these knees are pointed straight ahead).

These studies are truly just the tip of the iceberg, as there is a larger body of evidence suggesting that the overwhelming majority of people in general, and especially athletes, have various forms of structural adaptations and sub-threshold pathologies. Importantly, not all of these individual will present with pain. In fact, the overwhelming majority will not. As Lorimer Moseley discusses in the video below, pain be tricky, as it is often context- and emotion-dependent. Furthermore, pain site and pain source are not always synonymous, as the irritated area may be doing everything right, but compensating for some other structural or functional limitation/dysfunction.

That said, structural adaptations will absolutely affect the individual’s movement. For example, an individual with FAI will have limited hip flexion range of motion, which will in turn limit squat depth, lunge depth, and step-up box height. If this limitation is ignored, the femoral head hits end range within the joint, which increases the stress to the hip labrum, but will also then cause compensatory movement, such as lateral flexion or rotation of the pelvis, or excessive flexion of the lumbar spine. If someone asked me how to tear a hip labrum and develop lumbar disc pathology simultaneously (I don’t get this question often), I would recommend they back squat past hip end-range repeatedly. In this scenario, you have compression from the ground up and the bar down going through a lumbopelvic complex that is undergoing multiplanar torsion, with at least one hip stuck at end range and grinding around that point.

As another example, consider a baseball player that presents with the same total rotation in both shoulders, but 20° more external rotation in his throwing arm. Can you imagine how doing exercises like a barbell snatch would drive rotation and other compensatory adjustments throughout the rest of the body as the throwing arm has significantly more motion overhead.

These are just a couple examples, to which there are many. The important thing is to recognize that athletes/clients present with unique structures and unique sets of postural and movement biases that will influence the execution of their training programs. Some of these things can be “corrected” or trained to a more optimal state, while others will simply just need to be accounted for in the individual’s exercise selection. Naturally, in order to recognize any of these things, it’s necessary to have a system of assessment/screening and a corrective approach.

In a couple days, I’ll be back with the second part of this series, “The Truth About Corrective Exercise”. If you’re interested in this topic, I’d encourage you to check out my 2-DVD set Optimizing Movement, which you can get for a $20 discount until next Saturday (December 7^th), as part of a special “Extended Black Friday Sale”. Click the link below for more information!

Get Optimizing Movement Now!

“…one of the best DVDs I’ve ever watched”
“A must for anyone interested in coaching and performance!”

Click here for more information >> Optimizing Movement

To your success,

Kevin Neeld
OptimizingMovement.com
UltimateHockeyTraining.com

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References:

Silvis, et al. (2011). High Prevalence of pelvic and hip magnetic resonance imaging findings in asymptomatic collegiate and professional hockey players. American Journal of Sports Medicine, 39(4), 715-721.
Birmingham, et al. (2012). The effect of dynamic femoroacetabular impingement on pubic symphysis motion: a cadaveric study. American Journal of Sports Medicine, 40(5), 1113-1118.
Philippon, et al. (2013). Prevalence of increased alpha angles as a measure of cam-type femoroacetabular impingement in youth ice hockey players. American Journal of Sports Medicine, 41(6), 1357-1362.
Jakoi, et al. (2013). Sports hernia in National Hockey League players: does surgery affect performance? American Journal of Sports Medicine, 41(1), 107-110.
Larson, et al. (2013). Increasing alpha angle is predictive of athletic-related “hip” and “groin” pain in collegiate national football league prospects. Arthroscopy, 29(3), 405-410.
Hack, et al. (2010). Prevalence of cam-type femoracetabular impingement morphology in asymptomatic volunteers. The Journal of Bone and Joint Surgery, 92(14), 2436-2444.
Jensen, et al. (1994). Magnetic resonance imaging of the lumbar spine in people without back pain. New England Journal of Medicine, 331(2), 69-73.
Miniaci, et al. (2002). Magnetic resonance imaging of the shoulder in asymptomatic professional baseball pitchers. American Journal of Sports Medicine, 31(1), 66-73.

Olympics, Breathing, PRI, and Athletic Excellence

I spent the weekend in Phoenix, AZ at a PRI Vision course and spending some time with Neil Rampe, Charlie Weingroff, Doug(las) Kechijian, and a couple guys from the Diamondbacks staff. I still have a lot to digest and will spend some time studying the course materials over the next few weeks to see what I can do to improve my programs. As is always the case when I get together with these guys, I learned just as much outside the course as I did inside. A lot of great conversations!

I got back late last night, so I’m brain-fried right now and pretty far behind on a bunch of work (just found out I’m presenting in Philadelphia, twice, in two weeks…with no presentation started!). Fortunately, I was able to jump on a call with my friend Maria Mountain before I left and she just posted the recording of our call. In it, she asked me about:

U.S. vs. Canada Olympic hockey (this wasn’t a questioning as much as trash talking!)
How I use Postural Restoration Institute techniques with my athletes
How breathing can influence performance and recovery
The key qualities shared by exceptional athletes

The call isn’t overly long, but we cover a lot of good stuff, so make sure you check it out! Also, I don’t know all the details, but I know Maria is going to offer an AWESOME deal on all of our goalie training products, so if you’re a goalie and looking for great training opportunities, make sure you check out her site over the next few days: Hockey Training Pro

Listen here >> Hockey Training Interrogation with Kevin Neeld

In a couple days, I’ll be releasing the first part of a 3-article “Optimal Movement” series that dives into why recognizing structural and functional limitations is so important, what you need to know about corrective exercise, and how to individual programs in a group setting. Lots of great stuff coming in the next week. In the meantime, you can grab a copy of my 2-DVD set Optimizing Movement today for $20 off as part of an “Extended Black Friday” sale! Click the link below for more information!

Have a happy Thanksgiving and check back in a couple days for Part 1!

Get Optimizing Movement Now!

“…one of the best DVDs I’ve ever watched”
“A must for anyone interested in coaching and performance!”

Click here for more information >> Optimizing Movement

To your success,

Kevin Neeld
OptimizingMovement.com
UltimateHockeyTraining.com

Please enter your first name and email below to sign up for my FREE Athletic Development and Hockey Training Newsletter!

Understanding the Bilateral Deficit

As the next segment in my “Throwback Thursday” series, I wanted to repost an article discussing the bilateral deficit. This article was originally published in June of this year (2013, if you’re coming to us from the future), which doesn’t make it much of a throwback, but the last post on “Rethinking Bilateral Training” (which you can find at the link posted below) generated some questions about the topic so I thought it was appropriate to follow up with this one. Enjoy, and as always, post any questions/comments you have below!

Understanding the Bilateral Deficit

Over the last several years, the bilateral deficit has received a lot of attention in the training world. If you’re unfamiliar with the term, the bilateral deficient (in the lower body, where the majority of this research has been conducted) simply refers to a phenomenon whereby the sum of force production from each leg individually is greater than the force production of both legs together. I covered this topic in a fair amount of detail 5 years ago in an article for StrengthCoach.com, which Coach Boyle was nice enough to let me repost on my own site here: Rethinking Bilateral Training.

Since then, there seems to be the misunderstanding that anytime an exercise is performed with one limb with a load greater than 50% of the two limb equivalent (e.g. a 180lb 1-leg stiff-legged deadlift versus a 300 lb 2-leg stiff-legged deadlift), that the explanation lies within the bilateral deficit explanation. It’s important to remember that the bilateral deficit is largely a neural phenomenon. While limitations in neural drive can certainly be a limiting factor in exercise performance, especially with fatigue or with untrained individuals, it is far from the ONLY limitation to exercise performance. Two of the more common culprits are stability and force production from other musculature.

Stability as a Limiting Factor

If you draw a rectangular box around your feet during a traditional back squat, the box represents your base of support. Naturally, a narrower stance would narrow the base of support, as would having smaller feet. During a traditional back squat, lateral stability isn’t likely to be a limiting factor to performing the exercise. Some novice lifters have trouble with anterior-posterior (front-back) stability, as the rectangle is much wider side-to-side than it is front-to-back.

In contrast, during a split squat (which I recognize is a different pattern altogether), the base of support represented by a rectangle drawn around the feet may be of comparable area to the traditional squat, but now the rectangle is much longer front-to-back and narrow side-to-side. Simply, this means that anterior-posterior stability is sound, and lateral stability is more likely to be compromised or a limiting factor in the exercise.

Lastly, during a 1-leg “pistol” squat, the base of support is only as large as the individual’s foot. In this example, anterior-posterior AND lateral stability are compromised. This significant decrease in the base of support will absolutely limit the external load the athlete can use during this exercise. If someone can back squat 400lbs and only 1-leg squat 50-100 lbs of external load, the bilateral deficit may still be in play, but the limiting factor to further loading in this exercise does not lie in a neural drive explanation, but instead in a compromised stability one.

The limiting factor to Jen Poulin pulling 495 is not likely to be her base of support.

Note the considerably decreased base of support and therefore greater challenge to stability with this exercise compared to the traditional deadlift.

At this juncture, it’s worth pointing out that comparing external load to internal load across exercises is somewhat vague. One of the proposed benefits of SOME single-leg exercises is that you’re able to load the involved musculature to a greater degree using less external load compared to double-leg exercises. For example, Coach Boyle stated several years back that at a certain point for most athletes, the ability to stabilize through the core/torso during the back squat becomes the limiting factor to increasing squatting load.

Using this thought process, let’s postulate that an individual can stabilize sufficiently to squat 400 lbs, but not 405. Knowing that the core can’t maintain regional integrity and stiffness above this load, it’s logical that an athlete may be able to rear foot elevated split squat (to full depth) with 275. While the loading pattern is different, the difference between the load used in the single-leg variation is notably higher than 50% of the bilateral version because the limiting factor of core stability is removed, and the true threshold of lower body force production capacity is more closely approached. This may also provide evidence in favor of the bilateral deficit. Tying things back to the original discussion on stability as a limiting factor, at some point of loading, lateral stability in this exercise is likely to limit further external loading, but in my experience this point is still well beyond the 50% back squat load and therefore still holds merit as a progression or alternative to traditional squatting. This, of course, is in addition to the other benefits of single-leg exercises, which is beyond the scope of this discussion.

Additional Muscular Force Production as a Limiting Factor

Recently, there have been a few discussions on single-leg Olympic lift variations. As with almost any exercise, I think it’s possible to develop an argument for why these variations hold merit, and how they may help improve some target athletic ability.

That said, I don’t think the differences between loads used in double-leg and single-leg O-Lift variations lies in the bilateral deficit. If an athlete has a hang clean 1-RM of 200 lbs and has optimal technique, the limiting factor to increasing loads is likely to lie in an inability to generate enough extension force/velocity to accelerate the bar upward. It’s likely that this athlete would be able to put 50% of this load (e.g. 100 lbs) on the bar, set-up in a high hang position (bar above mid-thigh) and simply shrug hard and drop beneath it to catch it. In other words, even with a damped lower body/hip component, the athlete can move 50% of the full hang clean load. This is an important point when looking at the differences between double- and single-leg Olympic lifting variations because the lower body component has been decreased, but the upper body component is the same. With any lateral stability, the athlete SHOULD be able to single-leg clean more than 50% of their double-leg load because they aren’t truly cutting their force generating musculature in half. This really highlights the importance of considering ALL of the musculature involved in a given lift.

As you can imagine, the limiting factor in a one leg clean will likely come back to lateral stability, and ability to center the bar over the support leg, which comes back to the previous discussion. As another example, a strong athlete may be able to hang snatch a 100lb DB, but not a 110 because of an upper body power limitation, which would clearly not be a limiting factor for this athlete with a 60lb DB. Despite 60lb being over 50% of the 100lb load, an athlete may be able to 1-leg 1-arm snatch a 60lb DB because the limiting factor has now changed from an upper body power limitation to potentially a lower body stability/base of support one. Ultimately, understanding the limiting factor in the performance of any given lift is key toward improving within that lift or selecting a different exercise that may provide a higher ceiling.

To your success,

Kevin Neeld
OptimizingMovement.com
UltimateHockeyTraining.com

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“…one of the best DVDs I’ve ever watched”
“A must for anyone interested in coaching and performance!”

Click here for more information >> Optimizing Movement

Passion, Vitamin D, and Stress

I’ve been buried at work this week trying to work on a few different projects, so I haven’t had much time to write. Fortunately, I’ve come across a few great articles/videos that I think you’ll enjoy. Check them out at the link below:

Does your player have the passion necessary to become elite? from Josh Levine
This is another piece from Josh Levine discussing long-term athletic development concepts that I really enjoyed. In my mind, athletic success almost always stems from this key component, which seems to paradoxically be what most youth sports systems kill/challenge first. If I were a youth sport parent, coach or administrator (in any sport), I would print this article out and read it everyday before I went to work. It’s easy to get caught up in performance and lose sight of the most important part of sports participation, especially at younger ages. Remember, EARLY development and ELITE development are not the same thing.

Vitamin D Deficiencies in Soccer Athletes (Premier League) from Matt Siniscalchi
Matt, who is celebrating a birthday today (Wish him happy birthday here: Matt Siniscalchi), recently wrote a succinct, but very clear summary of Vitamin D deficiencies in elite athletes and why Vitamin D is so powerful. As I’ve mentioned in the past, I tend to think of supplements as falling within one of two buckets: Performance or Health. The reality is that you can’t REALLY separate health from performance, but the distinction helps illustrate why everyone may want to look into certain “health” supplements (e.g. Vitamin D), whereas a “performance” supplement like Beta Alanine may be reserved for competitive athletes in specific sports. More great stuff from Matt.

How to make stress your friend from Kelly McGonigal
This is a TED Talk video that I came across last week and really enjoyed. In the video, Dr. McGonigal discusses how our interpretation of stress influences how we react to it. This, as a stand alone statement, is fairly intuitive, but the repercussions of this simple idea are significant. At the end of the video, she says “Chasing meaning is better for your health than trying to avoid discomfort.” This statement can be interpreted in a variety of ways, but within the athletic realms it seems to highlight how hard work (in the sport or in training settings) could be interpreted differently physiologically depending on whether or not the athlete is passionate about the sport, which again highlights why you should read the first article every day! Check out the video below:

To your success,

Kevin Neeld
OptimizingMovement.com
UltimateHockeyTraining.com

Please enter your first name and email below to sign up for my FREE Athletic Development and Hockey Training Newsletter!

Get Optimizing Movement Now!

“…one of the best DVDs I’ve ever watched”
“A must for anyone interested in coaching and performance!”

Click here for more information >> Optimizing Movement

Rethinking Bilateral Training

Over the last 5 years I’ve written over 650 articles for this site. It’s a little crazy to think about!

Because of the sheer volume of content, I find myself answering a lot of emails these days by searching for old articles I’ve written that answer the person’s question and just firing them back over. The reality is that I may be the only person among us that has read every one. In short, there is probably some good stuff that you guys are missing out on!

It’s for this reason that I’m starting a new “Throwback Thursday” series that will highlight an article from the past that still contains information that is relevant today. This will be a great way to reignite some conversation and discuss what (if any) changes in philosophy/training methods have resulted since these were first written. Today we’ll kick things off with an article that covers what I still feel is a fairly controversial topic (extremists on both ends). Enjoy!

Rethinking Bilateral Training

Bilateral training frequents athletic development programs everywhere. By bilateral I mean both legs or arms working simultaneously to produce force/motion in the same direction. Exercises such as front squats, deadlifts, standing shoulder press, and bent over row are just a few examples. While bilateral training and the associated exercises are deeply rooted in the history of strength training, it may be time to reconsider their use. Heresy you say?

I’m certainly not the first to make this suggestion. Michael Boyle has been making the case for single-leg training for years now. After reading one of his articles on the topic, I began thinking more about the lack of respect single-leg training receives. As the article mentions, people are probably reluctant to use single-leg training because they require less external load. This raises a few more questions. Is external load completely indicative of internal stress to the muscle? If so, is neglecting the movement pattern and maximizing the external load really the goal of training athletes? The article also mentions the “functional” inclusion of the medial and lateral musculature of the hips that is present in single-leg training and not bilateral training, functional being defined as “training the muscles that we’re using in the way that we use them.”

I want to preface the rest of this article by stating that I’m not yet calling for a complete abandonment of bilateral training. Instead I simply want to present some of the research supporting the empirical evidence that Coach Boyle presented in his T-nation article. In light of the available research on the nervous system, a working knowledge of functional anatomy, and injuries associated with heavy spinal loading, I think it is time to reconsider the efficacy of predominantly bilateral training programs.

Neural Hinderance?

A look into the literature on the nervous system’s role in force production revealed an interesting occurrence known as the bilateral deficit. For those of you that aren’t familiar, the bilateral deficit simply describes the fact that the sum of individual extremity force production is greater than bilateral force production (1-5). In other words, if you performed a one-legged knee extension with your left leg only, then your right leg only, and added these two forces together, they would be greater than if you performed a knee extension with both legs together. Bilateral Deficit: Leg A + Leg B > Both Legs
In fact, the bilateral deficit is said to be as large as 20% (6,7) during slow contractions and as high as 45% (7,8) during rapid contractions! Luckily, researchers were quick to monitor the changes in this relationship following a bilateral resistance training program and found that the deficit decreased. In some instances the relationship even reversed so that both legs produced more force than the sum of individual leg efforts (9,10). Phew! Disaster averted.

Neural scientists refer to the bilateral deficit as a phenomenon. I would question whether it is a phenomenal occurrence or a long-term adaptation to repeated movements. As many of you already know, performing a movement repeatedly strengthens the associated neural circuitry resulting in improved force production. In the words of my old neurobiology professor, “Neurons that fire together, wire together.” This is the primary explanation for why novice lifters can experience rapid gains in strength in the first eight weeks of training.

Is it possible that the bilateral deficit is simply a life-long adaptation to producing force on one-leg? I realize that no one grows up performing one-legged squats off their kitchen stools on a daily basis, but think about the movements we perform regularly, notably walking and running. While one leg is producing a triple-extension force, the other is usually producing a triple-flexion force. Let’s come back to the knee-extension example. In consideration of the “neurons that fire together, wire together” statement, it would make sense that as one leg is extending the neural circuitry is telling the other to flex. This pattern predominates in most human movements: walking, skipping, running, and even crawling!

The neural circuitry to explain this pattern is well-established. Some of you may have been introduced to it through the flexor crossed-extensor reflex. In this example, if someone steps on a sharp object or other painful stimulus, they will withdrawal that leg by flexing the hip and knee. At the same time, they will extend the hip and knee on the other leg. This is a stabilization mechanism. If both hips and knees flexed, you’d like end up sitting on the painful stimulus you’re trying to avoid. Basically, as the flexor group on one limb is excited, the contralateral flexor group is inhibited, and the contralateral extensor group is excited.

What does this have to do with athletes?

We are wired to effectively produce unilateral movements. Athletics involve unilateral movements. Most strength and conditioning programs revolve around bilateral movements. Why? I understand the benefits of including single-leg training is being increasingly recognized and that more unilateral training is being prescribed. However, it still seems that we’re adding some single-leg training to a double-leg program, instead of the other way around. What happens if we abandon double-leg training altogether? Compared to double-leg training, single-leg training:

1. Requires greater force production from more muscles. Picking up one leg immediately requires greater force production from the hip abductors and adductors (among others) to stabilize the pelvis. Some of the affected muscles would include: pectineus, adductor brevis, adductor longus, adductor magnus, gracilis, obturator internus, obturator externus, gluteus maximus, gluteus minimus, gluteus medius, psoas major, iliacus, sartorius, gemelli inferior, gemelli superior, piriformis, and tensor fascia latae.

2. Increases the proprioceptive and sensory demand. Decreasing stability by narrowing the base of support will absolutely necessitate greater proprioceptive and sensory feedback to maintain balance.

3. Decreases spinal loading. I’ve heard a saying a few times that goes something like “Live your life the wrong way, you’ll end up in a cardiologist office. Live your life the right way, you’ll end up in an orthopedic office.” This has come to be accepted as an inevitable truth. Research supports the idea that repetitive heavy spinal loading, as is common in long-term weightlifting, results in a myriad of spinal issues including an increased incidence of spondylosis (11), decrease in intervertebral disc height (12), lumbar spine degeneration (13). But does it need to be this way? If we can maintain or even improve the quality of the stimulus to the muscle and cut the external load in half, could some of these injuries be prevented?

4. Reinforces the neural circuitry common to most athletic movements. The majority of athletic movements occur from one-leg or a staggered stance. Could this more similar training approach help to decrease the incidence of injury? I’m thinking specifically of hamstring strains and ankle sprains. Hamstring strength absolutely plays a role in preventing hamstring strains. But how do we explain the athletes with monstrous hamstrings that suffer an injury? Bad running form? Maybe. Is it possible that these strains are occurring due to a neural mishap associated with hamstring momentarily attempting to contract concentrically bilaterally when one side should be lengthening? The causative factors associated with ankle sprains remain relatively allusive, but there does seem to be some evidence that decreased proprioception and increased peroneal stretch reflex latency may be related to ankle injury. As a global factor, fatigue seems to be related to injury, with more injuries occurring as fatigue increases. Of interest is that muscle fatigue is training-specific, meaning that if double-leg training predominates, the athletes will resist fatigue more efficiently in double-leg movements than single-leg movements.9 Naturally, the opposite is also true. Both of those factors are neural in nature, and may be positively affected by the increased demand on the sensory system provided by single-leg training. Prior history seems to be the greatest predictor of future injury. Therefore, if we can prevent an injury from ever happening, we significantly decrease the risk of future occurrences.

Admittedly, some of the proposed benefits of single-leg training on injury prevention are speculative. There is a clear list of benefits to single-leg training, however, that shouldn’t be overlooked. While I believe that largely moving away from double-leg training is premature (and somewhat scary), I think it is worth considering. Albert Einstein once said, “The significant problems we face cannot be solved at the same level of thinking we were at when we created them.” Weigh the pros and cons associated with eliminating double-leg training. Is it time for a change?

This article was originally published on StrengthCoach.com, an athletic development website where some of the world’s experts in strength and conditioning print their articles and discuss current issues.

To your success,

Kevin Neeld
OptimizingMovement.com
UltimateHockeyTraining.com

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Get Optimizing Movement Now!

“…one of the best DVDs I’ve ever watched”
“A must for anyone interested in coaching and performance!”

Click here for more information >> Optimizing Movement

References

1.    Obtsuki, T. (1983). Decrease in human voluntary isometric arm strength induced by simultaneous bilateral exertion. Behavioural Brain Research, 7, 165-178.
2.    Schantz, P., Moritani, T., Karlson, E., Johansson, E., & Lundh, A. (1989). Maximal voluntary force of bilateral and unilateral leg extension. Acta Physiologica Scandinavica, 136, 185-192.
3.    Secher, N., Rorsgaard, S., & Secher, O. (1978). Contralateral influence on recruitment of curarized muscle fibres during maximal voluntary extension of the legs. Acta Physiologica Scandinavica, 103, 456-462.
4.    Secher, N., Rube, N., & Ellers, J. (1988). Strength of two- and one-leg extension in man. Acta Physiologica Scandinavica, 134, 333-339.
5.    Taniguchi, Y. (1998). Relationship between the modifications of bilateral deficit in upper and lower limbs by resistance training in humans. European Journal of Applied Physiology and Occupational Physiology, 78, 226-230.
6.    Howard, J., & Enoka, R. (1991). Maximum bilateral contractions are modified by neurally mediated interlimb effects. Journal of Applied Physiology, 70, 306-316.
7.    Koh, T., Grabiner, M., & Clough, C. (1993). Bilateral deficit is larger for step than for ram isometric contractions. Journal of Applied Physiology, 74, 1200-1205.
8.    Vandervoort, A., Sale, D., & Moroz, J. (1984). Comparison of motor unit activation during unilateral and bilateral leg extension. Journal of Applied Physiology, 56, 46-51.
9.    Rube, N., & Secher, N. (1990). Effect of training on central factors in fatigue following two- and one-leg static exercise in man. Acta Physiologica Scandinavica, 141, 87-95.
10.    Enoka, R. (1997). Neural adaptations with chronic physical activity. Journal of Biomechanics, 30, 447-455.
11.    Aggrawal, N., Kaur, R., Kumar, S., & Mathur, D. (1979). A study of changes in the spine in weight lifters and other athletes. British Journal of Sports Medicine, 13, 58-61.
12.    Granhed, H., & Morelli, B. (1988). Low back pain among retired wrestlers and heavyweight lifters. American Journal of Sports Medicine, 16, 530-533.
13.    Videman, T., Sarna, S., Battie, M., Koskinen, S., Gill, K., Paananen, H., & Gibbons, L. (1995). The long-term effects of physical loading and exercise lifestyles on back-related symptoms, disability, and spinal pathology among men. Spine, 20, 699-709.