Tag: Athletic Development Resources

Strength Coach Success Secrets: Exclusive Interview with Mike Robertson Part 1

KN: First off, I want to thank you for taking the time out of your busy schedule to do this. Can you please introduce yourself to those readers that may not yet know you?

MR: Sure thing Kevin! My name is Mike Robertson and I’m a strength coach/personal trainer in the Indianapolis area. Bill Hartman and I are the co-owners of a gym called Indianapolis Fitness and Sports Training (I-FAST). As well, I am the president of Robertson Training Systems, where I do consulting, public speaking, and writing on the topics of strength training, injury prevention, etc.

KN: What were some of your stops along the way? Where did you work previously, intern, volunteer, observe, etc.?

MR: It seems like I’ve done a little bit of everything along the way!

I started out like most of us; reading muscle rags like Muscle and Fitness and Flex. I always knew in the back of my mind that I didn’t necessarily want to look like a bodybuilder, but I enjoyed working out and this was the only real information I could find on the topic.

In the summer of 2000 I interned in the Ball State University athletic weight room and fell in love with coaching. I spent the next 2.5 years of my life volunteering time and soaking up everything I could. I was going through a Masters program at the time, and I also began competing in the sport of powerlifting. Needless to say, I was totally immersed in the field!

Upon completion of my Masters Degree I moved to a small city in northern Indiana called Ft. Wayne. There, I continued powerlifting and was the director of the Athletic Performance Center. The name was a little misleading, as I was really doing more chiropractic-based rehab than anything else. This is where I really started delving into corrective exercise, posture, alignment, and figuring out how the body worked as a functional unit.

After 3 years in Ft. Wayne, I really missed my friends so my wife and I packed up and moved back to Indianapolis. This is when I started Robertson Training Systems, and I also did quite a bit of in-home personal training. After 3 years doing this, I decided it was time to buckle down and get the gym open. The rest, as they say, is history.

KN: Sometimes I think people assume that coaches with a bodybuilding or powerlifting background only train their athletes like bodybuilders or powerlifters. Despite your history in powerlifting, you’re often thought of as a “corrective exercise” guy. Can you expand on how your athletic/lifting background influenced your training philosophy?

MR: I think I get pigeon-holed a lot as a “mobility” guy or a “corrective” guy, but I like to think of myself as a results guy. I’m not really a slave to any system or dogma; I just want the best for my clients, and I want them to get results.

I think my powerlifting background will always push me to load up the weights a bit, but again, I try and keep perspective as to how I train people. Just because I like to powerlift doesn’t mean it’s the best thing to help my clients achieve their goals!

If anything, I think my background as an athlete is more evident than my experience as a powerlifter. Whether I’m working with an athlete, a fat loss client, or anything in between, I want people to train more like athletes. Simple things like med ball exercises, including tire flipping or kettlebell work, etc. seems to be more enjoyable for all my clients and makes them work harder in the long run.

KN: I’ve noticed that some of my “general population” clients really enjoy training like athletes too. I think it’s important that they enjoy what they’re doing so that they continue to stay active, even beyond our time together.

On a different note, among academics it doesn’t seem like the strength and conditioning profession gets much respect. Why do you think this is? Are all strength coaches genetically predisposed to intellectual inferiority??

MR: Honestly? I think we don’t get much respect because we don’t educate ourselves enough! There’s far too much bro-science in the industry, and it’s got to stop if we want to take our industry to the next level.

Now understand, I do my best to balance the science (i.e. studies) and the practice (what works in the gym). If you lean too far one way or the other, you’ll miss out on some good info. I think you’re seeing a shift to this mindset now; some of the old-dogs that are using outdated methodologies are being replaced by coaches who are well-read, but also have the in-the-trenches experience to bring it all together.

KN: Brian Tracy talks about investing 3% of your income in professional development. I know I’ve heard Eric Cressey talk about the thousands of dollars he spends on professional development every year. Any idea on how much time/money you spend on new products, seminars, etc.?

MR: Probably too much! In all seriousness, I have no clue how much I spend at this point in time, but for a while I was taking 10% of all my business profits and putting it back into continuing ed!

I can’t tell you how many seminars, books, DVD’s, etc. I’ve reviewed in the past year. I know that pretty much every night I’m reading something related to the field or my business. It’s weird; I almost feel like I’m doing something wrong if I just read a powerlifting USA or something similar at night! I feel like if I’m not reading something educational, I’m going to miss something. There’s so much to learn – on one hand it’s kind of daunting, but on the other hand the more you read and learn the more you respect how cool the human body is.

KN: Can you talk about how continuing education has been instrumental in your success? What resources/seminars do you rely on for new information/ideas?

MR: I will constantly tell people that I learned more in the 6 months I got out of college than I did in the 6 years I was in college, simply because I focused on what I needed to learn!

Continuing education is hugely important. All school does is a lay a foundation, but it’s on you to fill in the gaps. As well, in the information age there’s so much great info being spread around my great coaches, if you don’t continue to learn you’ll be left behind!

Coming out of school I always felt comfortable coaching and teaching exercises, but my knowledge of functional anatomy and “corrective” exercise was pretty weak. I think over the years I learned how imperative these tools were, and now that’s actually a strong point in my repertoire.

As far as resources go, I always say I’m willing to learn from anyone who has something of value to teach. This could be websites like T-Nation or Elite Fitness, research articles from sites like Pubmed, DVD’s, seminars, etc. And finally, don’t forget that just like you need a network of other great professionals, always try and network with other trainers as well. What are they doing to get great results?

Stay tuned for Part 2…
Kevin Neeld, BSc, MS, CSCS is the Director of Athletic Development at Endeavor Fitness in Sewell, NJ and the author of Hockey Training University’s “Off-Ice Performance Training Course,” a must-have resource for every hockey program. Through the application of functional anatomy, biomechanics, and neural control, Kevin specializes in guiding hockey players to optimal health and performance. Kevin developed an incredible ice hockey training membership site packed full of training programs, exercise videos, and articles specific to hockey. For a FREE copy of “Strong Hockey Core Training”, one of the sessions from his course, go to his hockey training website.

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Isolation Stretching

by Kevin Neeld

To stretch or not to stretch…Why is this still a question?

There is more than enough research showing that stretching before activity decreases performance measures (strength, power, speed, balance, etc.). Compared to a static stretching warm-up, a dynamic warm-up lead to significantly greater increases in these same measures. The misinterpretation of this research has lead to the idea that static stretching is completely unnecessary.

Makes sense right? I mean if an activity meant to elicit relaxation and passively lengthen muscle doesn’t lead to immediate performance improvements, why do it at all?

I’m not the type to just accept something I’ve read. I’m also not the type to discount something I’ve read just because it doesn’t make sense to me. So following the complete lack of logic behind never stretching again, I decided to conduct the ultimate research experiment…I stopped stretching altogether. For 6 weeks I didn’t stretch once. Not my legs, not my shoulders, not my neck, nothing. I ran with the idea that simply moving through a full range-of-motion (ROM) consistently would be enough to improve, or at a minimum maintain joint ROM.

The results: The study was cut short from an original 8-week proposal due to the only subject feeling like complete hell. Not only did I lose active and passive ROM around my ankles, knees, hips, and shoulders, but I started to get exceptionally tight in variable areas that would lead to nagging aches and pains.

Backed with this convincing research, everyone should be stretching AFTER their training. Stretching at this time allows you to relax, and return chronically shortening muscles to their original length. To avoid omitting potentially important information, I’ll tell you that I’ve heard that stretching muscles cold may actually lead to long-term flexibility increases, while stretching warm muscles may lead to more short-term changes. If you’re disciplined enough to do your stretching at another time, this may be an option to consider. In a team setting, it just doesn’t work. Many athletes don’t like stretching and won’t do it if they aren’t supervised. If you’re a coach, the only way to guarantee that all your athletes are stretching is to watch them do it after practice. If you’re an athlete and hate stretching-just do it immediately after your lift/practice.

Now that we understand that stretching is a necessary component of a well-designed training program, let’s talk about how to get the most bang for your buck out of your stretching time. There are a few tricks to address muscles that traditional stretches may miss. Moving from the ground up:

Plantarflexors (or calves): While the soleus and gastrocnemius are both plantarflexors, only the gastrocnemius crosses the knee joint, allowing it to assist in knee flexion. Because of the difference in origins between the two muscles, the plantaflexors should be stretched with both a bent knee (greater emphasis on the soleus), and an extended knee (greater emphasis on the gastrocnemius). While stretching these muscles with an extended knee may stretch both muscles, the magnitude of the stretch on the soleus will be limited by the stretch of the gastrocnemius. In other words, if the gastrocnemius is really tight, the the soleus will not be sufficiently stretched. Bending the knee and stretching again puts the gastrocnemius on slack, allowing a greater focus on the soleus.

Soleus Stretch

Gastrocnemius and Soleus Stretch

Hip Flexors:
I have yet to see an athlete that didn’t have tight hip flexors. Stretching this muscle group is extremely important. Most people are familiar with the lunge stretch. The focus of this stretch is primarily on the iliacus and psoas muscles. What many people don’t consider is that one of the quadriceps muscles, the rectus femoris, is also a hip flexor. This two joint muscle works to flex the hip and extend the knee. Since most people perform quad stretches with a slightly flexed hip, this muscle frequently passes under the radar. The solution is to find a stretch that extends the hip and flexes the knee, which is possible through a slight modification to the well-known lunge stretch. The tensor fasciae latae (TFL) is also a hip flexor. This muscle connects with the IT band, which means that TFL tightness can lead to a ‘tight’ IT band, which can have implications on patellar tracking (a lateral pull on the knee cap). Unfortunately the TFL is very difficult to stretch. Below is a simple variation to the other hip flexor stretches that puts a slightly greater emphasis on the TFL. Notice that the feet are closer to an in-line position than a hip-width position.

Iliacus and Psoas Complex Stretch

Rectus Femoris Stretch

Tensor Fasciae Latae Stretch

Adductors (or groin muscles):
The majority of the adductors originate on the ischial tuberosity (the bony prominence that you sit on) or pubis and attach to varying positions on the femur. The gracilis, however, attaches to the medial tibia. This means that the gracilis not only spans the hip joint, but also the knee joint. Functionally, this muscle cannot be stretched if the knee is bent, as in most “groin” stretches. However, only stretching these muscles with the knee extended may limit the magnitude of stretch to all the adductors other than the gracilis. Stretching them twice, once with a bent knee and once with an extended knee, may be the most effective way to stretch this group.

Pectineus, Adductor Brevis, Adductor Magnus, Adductor Longus Stretches

Gracilis Stretches

Pectoralis Major (and anterior shoulder):
The pectoralis major has a unique fiber orientation with the direct line of pull of individual muscle fibers changing relative direction throughout the muscle. In other words, from top to bottom, the fibers are angled diagonally downward, horizontally, and diagonally upward. Consequently it makes sense to stretch this muscle in at least two different positions, 90° and 135°. Time permitting it may be worth stretching this muscle at a lower angle (~60°); although I’ve found this angle to be the least beneficial of the three. Notice how my forearm is supinated and my upper arm externally rotated. The pectoralis major is also a humeral internal rotator. I’ve found this stretch to be much more effective by arranging my arm and forearm into this position. I also like to keep my elbow fully extended because it adds a greater stretch to the biceps brachii, allowing for an effective stretch of all the muscles that cross the anterior shoulder.

90° Stretch

135° Stretch

External Humeral Rotators:
Like the pectoralis major, the fiber orientation of the infraspinatus (one of the rotator cuff muscles) changes from a horizontal direction to a more diagonal direction as you move from the top down. In order to maximize the effectiveness of stretching the external rotators, it makes sense to stretch these muscles at two angles, 90° and 135°.

90° Stretch

135° Stretch

I generally recommend that each stretch is held for 30 seconds, and that static stretching isn’t performed until AFTER the training session. I think it’s a great way to keep the blood flowing a little, cool down, and relax. However, since many of these stretches address specific areas that are problematic for a lot of people, it may be beneficial to run through a quick circuit of these stretches BEFORE the training session, holding each position for only 10-15 seconds and actively contracting the antagonist muscle groups. If you aren’t stretching at all, start. Maintaining proper tissue length will allow you to keep progressing through your training while minimizing the risk of unnecessary injury.

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

Kevin Neeld, BSc, MS, CSCS is the Director of Athletic Development at Endeavor Fitness in Sewell, NJ and the author of Hockey Training University’s “Off-Ice Performance Training Course,” a must-have resource for every hockey program. Through the application of functional anatomy, biomechanics, and neural control, Kevin specializes in guiding hockey players to optimal health and performance. Kevin developed an incredible ice hockey training membership site packed full of training programs, exercise videos, and articles specific to hockey. For a FREE copy of “Strong Hockey Core Training”, one of the sessions from his course, go to his hockey training website.

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

Bike Riding Doesn’t Have to be a Pain in the Neck!

By Lex Gidley and Kevin Neeld

There are a myriad of sources in print and on line which explain the ins and outs of why a cyclist’s back and neck hurt. Many proclaim that proper bike fit, technique, and even helmet fit can be the sources of the pesky pains we suffer as the season wears on. And while these and other sources may be the reason our seasons feel so long sometimes, let’s face it, even if we followed all the recommendations we would probably still have pain. The human body was not meant to be in one position for so long. This article will not be a synopsis of all the literature telling fellow riders what to do to decrease the pain, but it will address what the pains are and how one can help ease the pain. Many of us don’t have the money to get all the “best” equipment, the best bike fit, or have time to really work on technique; we just get on and ride. So, how can we fight the pain? With a few corrective exercises!

What are the pains? Simply put, it is muscle and/or nerves. Sometimes the muscles are stressed due to what is termed “over-use” injury, and based on the positions we sit in for hours on end we can be pinching nerves. Our necks are held in hyper-extension as we try to look up to see where we are going, shoulders are usually held in a forward position as we stretch forward bracing ourselves against our handlebars and to make things worse we are stuck in this position unless we make the effort to relax our arms and use our core for support or shift from the hoods to the drops periodically or get off our bike. So, as we slowly chip away at easing the pain by paying money for proper bike fitting appointments, buying new helmets, handle bars, and for massages to release the stress, we can also participate in some exercises that may ease our body and make our seasons more enjoyable.

The hunched over biking position we all adapt to rather quickly can lead to some specific postural changes. Notably, the shoulder blades (scapulae) drift outward, the upper spine (thoracic spine) becomes more flexed and loses mobility, the head sits forward, and the arms become internally rotated. First, the most important thing to remember when addressing these problems is that you need to avoid this hunched over position throughout the rest of your day. Most of us practice this “biking position” throughout our normal activities: at the computer, talking on the phone, even walking can be altered due to our new “relaxed” upper back position. While many of the changes will need to be conscious: “I will sit up straight!” some may be prevented by changing your surroundings. For example, if you spend a considerable amount of time in front of a computer, use a chair with a supportive backrest and armrests. You can also take care of yourself at work or home by changing your posture constantly and by taking frequent breaks to stand up and stretch out, e.g. microbreaks.

Additionally, there are a few exercises that can be performed quickly that can help minimize the discomfort associated with these undesired structural changes. If performed in a circuit these exercises shouldn’t take more than 8-10 minutes. These exercises should be used in conjunction with (not as a replacement for) a structured resistance training program.

Exercises

Chin Retractions 2 x 20sec
Simply put, with a support for your head and shoulders, like a wall or the floor, forcibly try to push your neck flat against the surface. Think of “tucking” your chin or making a “double-chin.” You should feel the muscles in the front of your neck working. It may help to push your tongue against the roof of your mouth. While stretching your neck after a long ride makes your neck feel better, this exercise is more active, retraining your neck muscles to keep your head in alignment through muscular activity.

Thoracic Mobility: Foam Roller Extensions 1 x (3 x 5 sec)
Lie on a foam roller placed just below your scapulae. Spread your shoulder blades apart by pulling your elbows up. Use your hands to support your head. While keeping your butt on the ground and your core tight, arch your back over the roller. Hold this position for 5 seconds, then move the foam roller slightly up your back and repeat. Perform this exercise in 3 positions for 5 seconds each. All three positions should be within your shoulder blades (not too high up your neck or too low on your back). This stretch just feels really good. Don’t get spooked when you hear/feel your upper back crack, it will the first time, but the second and third time will be good stretches and feel really good on the stiff upper back.

Stick Dislocations 1 x 12
Using a broom handle, golf club, ski pole, etc. grab it with both hands more than shoulder width apart. Slowly raise your hands above your head, proceeding carefully behind your head until the stick reaches its lowest point nearest your hips. When the “stick” is overhead, pin your shoulder blades together and keep them pinned until the end of the movement. Return to the starting position and repeat. This exercise will increase the range of motion in your shoulders which can be reduced by the limited motion experienced while sitting in the saddle.

Stick Ups 2 x 10
Just as the name implies, this is a stick-up! Put your back against the wall and put your hands up. Use the starting position as a clean start to not arching your back and trying to keep your scapulae flat on the wall. As easy as that sounds, be sure to not arch your back to help put your arms flush with the wall. Keep your core tight to keep your back from arching, pulling your stomach muscles towards your spine. Pull your elbows in tight to your side, and then raise your arms straight overhead.

Push-Up Hand Switches 2 x 10
From a push-up position, lift on hand off the ground, shift your weight and place it on top of the other hand. Return to the starting position and repeat with the opposite hand. Make sure to keep your core tight throughout the whole movement! This exercise helps awaken some of the muscles around the scapulae that can become problematic from being in the same hunched over position for too long.

Glutes Bridge Hold 2 x 20sec
While keeping your heels on the ground (toes in the air), squeeze your glutes (butt muscles) to raise your hips off the ground. Try to maintain a straight line from your knees to your shoulders. Hold your hips off the ground by tightening your glutes, not by arching your back. Keep your hands on your stomach to make sure these muscles stay tight! Muscles can become weakened when they’re in a stretched position for too long. Sitting all day and biking all night keeps your glutes on stretch for most of the day. This exercise is helpful, when done correctly, to help restore the functioning of these powerful muscles.

Front Plank 2 x 20sec AND Side Plank 2 x 20sec (each side)

These drills are designed to develop core strength and stability, but they have the capability of strengthening the whole body like a push-up would, without the upper body stress. Place your two arms (front plank) or either arm (side plank) with your forearm flat on the ground. During the front plank, it is alright to have a slight bend in your waist in order to keep your hips from sagging. Notice on the side plank, the body is fairly straight, without a break between the upper and lower body. Arm is straight in the air, not pulling you backwards. Neither of these exercises should cause strain in your shoulders or neck. Using your core will relieve the stress in your shoulders and neck. Brace your midsection during these exercises as if someone was going to kick you in the stomach. Although your core (in the front AND the back!) is tight, you should still be able to breathe normally!

Scapular Stabilization Exercises 2 x 10-12 per position
In these exercises you will lie face down on a workout bench. Initially you will make an “I” with your arms (up and out in front of you), keeping the arms down, hands grazing the floor, then lift the arms up as high as possible. Then proceed to making a “Y” (arms out at a 45° angle) and then a “T” (arms straight out to the side) and lifting from each position. Think of initiating each of movement at the scapulae as opposed to just moving your arms and keep your thumbs pointed up. This exercise will help keep your scapulae from sliding forward and closing your chest, the way cycling can tend to do because of the position in which one remains for hours: hands out in front, arms stretched out, back hunched. Especially when we get tired and tend to lock out the elbows this position becomes accentuated and the muscles in the upper back become weak and can no longer keep the scapulae in place.

“I”

“Y”

“T”

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

Lex Gidley, MS, is currently a doctoral student at the University of Massachusetts, Amherst studying biomechanics. She is a level 3 ski instructor and clinic leader in the PSIA-Eastern division and actively competes in cycling, mountain biking and triathlon events.

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EMG for Strength Coaches

by Kevin Neeld

As strength and conditioning coaches, much of what we do involves training the neuromuscular system. Consequently, the more we can learn about the way the neuromuscular system works to produce force and coordinated movement the better we can train our athletes. One of the tools used to monitor the neural input to muscles is electromyography (EMG). EMG can be a confusing area because the signal is affected by so many different things, including well-known things like muscle fiber size and the number of muscle fibers, and less well-known things like body fat and blood flow. While much of the EMG research may be of interest to the strength and conditioning community, it’s important to understand what exactly it is and what it measures so that research isn’t misinterpreted. Hopefully this article will shed some light on EMG misnomers.

What is EMG?

EMG is a measurement of the electrical activity of one or more muscle fibers. In general, there are two types of EMG: surface EMG and indwelling EMG. Surface EMG is a more global measure of the electrical activity of the entire muscle. The electrical activity is a summation of the electrical activity of all of the individual muscle fibers within the measurable range of that particular electrode. Indwelling electrodes include both needle and fine-wire electrodes. These electrodes measure the electrical activity of a limited sample of muscle fibers most proximal to the electrode inside of the muscle, as opposed to on the surface. These electrodes are more effective at measuring changes in the quality and quantity of individual motor unit (MU) firing. For example, indwelling electrodes can assess things like: Individual motor unit firing rate changes. An individual motor unit will increase its firing rate in order to produce more force, as discussed below.

Incidence of doublet firing. Doublet firing involves an individual motor unit discharging twice at a very short latency. For instance, if a motor unit is discharging every 30 milliseconds (ms), and then discharges twice within 10 ms, this would be considered a ‘doublet’.

Common Drive. This word describes two motor units simultaneously changing their firing rates together. For instance, if MU1 increases its firing rate, MU2 will increase its firing rate at the same time. If MU1 decreases its firing rate, MU2 will simultaneously decrease its firing rate.

Synchronization. If two motor units discharge at almost exactly the same time, this is referred to as synchronization. Typically, if MU1 and MU2 discharge within 5 ms of each other, they are said to have fired synchronously.

All of the above examples are strategies that the nervous system uses to increase muscular force that can be most accurately measured using indwelling electrodes. While these electrodes are capable of providing extremely useful and interesting information, much of the EMG confusion is associated with surface EMG, so the rest of the article will focus on that.

What surface EMG is…

In general, surface EMG measures total muscle activation. It is important not to confuse activation with recruitment. Although the two words are sometimes used interchangeably, they are NOT the same thing! Recruitment involves additional motor units producing force. Activation includes both recruitment AND rate coding. As a refresher, rate coding involves an individual motor unit changing its firing rate. For any given motor unit, a faster firing rate will result in a higher force production than a lower firing rate. If you read that there was an increase in EMG activity, this could be due to the already active motor units increasing their firing rates, the recruitment of additional motor units, or, and probably most likely at lower force levels, both.

Also, surface EMG probably doesn’t measure activity from the whole muscle. Keep in mind that the same size electrode is used for muscles of all shapes and sizes. On a very small muscle, the electrode may be able to pick up activity from the whole muscle, and probably surrounding muscles (This is called cross-talk and is discussed later). That same electrode on a very large muscle will pick up activity from the most proximal muscle fibers, but probably not the deepest ones, which are typically more slow-twitch.

What surface EMG isn’t…

This is probably one of the biggest misunderstandings: Surface EMG is NOT indicative of the mechanical force production of the muscle. The electrical signal is the nervous system INPUT signal to the muscle. So when EMG activity increases, mechanical force production increases at a delay (typically around 50ms) that is dependent on the characteristics of the muscle fibers and the type of contraction. This means that when surface EMG activity is completely non-existent, the muscle can still be producing force. Remember, the muscle will continue to produce force as long as calcium is available. The decline in force production (both the shape and time course) is coincident with the uptake of remaining calcium back into the sarcoplasmic reticulum. The delay between electrical activity and measurable increases in muscular tension also makes it possible, during periods of very brief activation, for electrical activity to start and stop before any increase in muscular tension can be detected. Also, most contractions involve some amount of antagonistic co-contraction, especially at higher forces. This will have a significant effect on the amount of observed force.

To be overly simplistic, if the biceps are pulling with 20 pounds of force and the triceps are resisting through co-contraction with 5 pounds of force, the biceps will only produce 15 pounds of observed force. Consequently, it is possible that biceps activity will increase, but observed force production will actually decrease. This is also possible during fatiguing contractions. As slower twitch motor units are operating at maximal firing rates and still unable to maintain a given force level, more impulses are sent to fast twitch (more superficial) muscle fibers causing the surface EMG activity to increase, although force production may actually begin to decrease. As you can see, it is dangerous to conclude that an increase in EMG activity necessarily results in an increase in force production.

What influences surface EMG activity?

1. Number of muscle fibers: More muscle fibers = more activity

2. Muscle fiber diameter: Larger fiber diameter = more activity

3. Distance between electrode and muscle fiber: The closer the muscle fiber is to the electrode, the clearer the signal. Think of it like someone yelling something to you. If you were 10 yards away, you’d probably hear them loud and clear. If you were 50 yards away, slightly less clear, 150 yards, less clear, etc.

4. Preferential recruitment of fast-twitch fibers: Fast-twitch are typically more superficial than slow-twitch muscle fibers. Because surface electrodes record the most clear signal from the most proximal muscle fibers, it is possible that surface EMG measurements overrepresent fast-twitch muscle fiber activity.

5. Blood flow: EMG activity can be affected by the overlying blood vessels in the muscle. If there’s a blood vessel between the electrode and the active muscle fibers (there frequently is), this will affect the quality of the signal. Sticking with the yelling example, just imagine how different things sound with your head above and below water. Overly simple…maybe, but it’ll do for our purposes here.

6. Muscle fiber direction: Placing the electrodes perpendicular to the direction of the underlying muscle fibers results in a significantly decreased EMG amplitude compared to placing the electrodes parallel to the muscle fibers. You can imagine how difficult it is to consistently account for this, especially while measuring the activity of multi-pennate muscles.

7. Cross talk: In many instances, the observed EMG activity includes electrical activity from other nearby muscles. This is almost unavoidable in some areas of the body as many different muscles are packed into a relatively small area (the inner thigh region is a great example).

8. Motion artifact: Movement of the electrode on the skin surface will actually produce measurable activity.

This is by no means an exhaustive list. The EMG signal is also affected by a host of other things including: muscle fiber conduction velocity, amount of subcutaneous fat, interelectrode spacing, number of active motor units, motor unit firing rate, etc.

What we can learn from surface EMG

While there are clearly several limitations to surface EMG, it does have a few extremely beneficial uses.

1. Time of activation: Surface EMG is a great way to measure the latency between any sort of stimulus (response to a visual, auditory, or tactile stimulus, response to a stretch, etc.) and the initiation of a muscular response. This can be used to track different timing characteristics among stimulus modalities.

2. Duration of activation: A reasonably accurate measure of the duration of activation can be made from surface EMG. Although, as we discussed previously, the cessation of EMG activity does not mean the cessation of force production.

3. Crude estimate of amount of activation: Holding all other conditions equal, more EMG activity is indicative of an increased effort of the nervous system to produce more force.

4. Patterns of activation: During complex and ballistic movements, surface EMG can give us an idea of when certain synergistic and antagonistic muscles fire relative to one another as well as when certain postural muscles may fire before extremity movement (e.g. delayed transverse abdominis firing with low back pain).

Surface EMG continues to be a useful tool for research and professional purposes. Information about the neural strategies of producing force and coordinated movements can be of particular interest to strength coaches. Hopefully this article has been helpful in describing some of the factors that warrant consideration when reading and interpreting EMG research. If not, there’s always wikipedia!

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

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Dissecting the Sports Hernia

By: Kevin Neeld

In collegiate and professional athletics, the term “sports hernia” seems to be frequenting conversations more and more. While the diagnosis of a sports hernia seems to be increasing both in prevalence and media attention, the injury remains poorly understood and defined. An in-depth look into the associated research helps explain why there is so much confusion surrounding this injury.

“Sports” Hernia vs. “Traditional” Hernia

The primary reason for the confusion surrounding sports hernias is that there is no established definition of this injury. In fact, there isn’t even an agreed upon name for this injury, as sports hernias have also been referred to as: athletic pubalgia, sportsman’s hernia, Gilmore’s groin, athletic hernia, hockey groin syndrome, Ashby’s inguinal ligament enthesopathy, incipient hernia, and osteitis pubis (1). Generally sports hernias are a label given to a situation involving an athlete that has chronic pain in the lower abdominal or upper proximal medial thigh area. This pain is further aggravated by rapid rotational or kicking movements, sudden changes in direction, and anything that increases intraabdominal pressure (coughing, holding your breath, etc.). Typically these symptoms have persisted for an extended period of time and have not responded to non-operative treatments (rest, ice, heat, anti-inflammatory drugs, stretching, etc.). Physical inspection is unable to find any true hole in the abdominal or inguinal wall or protruding tissue, which are characteristics of “traditional” hernias (2). Essentially this means that sports hernias aren’t hernias at all. Naturally, then, the questions is: What is a sports hernia?

The most commonly accepted definition of a sports hernia is a weakening of the posterior inguinal wall. It is important to note, however, that this is one of MANY proposed definitions. Complicating the issue further is that sports hernias rarely occur in isolation. Upon surgical inspection, the following are commonly found:

A deficiency in the posterior wall of the inguinal canal (1-3, 5, 6)
A deficiency of the transveralis (1, 2, 4, 6)
A tear/strain in the conjoined tendon (common tendon of the internal oblique and transversus abdominis; 1, 2, 4, 6)
Dilation of the internal inguinal ring (1, 6)
Thin or torn rectus abdominis insertion (1, 2, 4, 6, 7)
Thinning or tearing of internal or external oblique aponeuroses (1, 2, 6)
Entrapment of ilioinguinal, genitofemoral, obturator, femoral, iliohypogastric, and lateral femoral nerves (1, 2, 6, 8)
Adductor tendinopathy (1, 5-7)
Iliopsoas complex strain (1)