What is the Stretch Reflex and how can you use it to improve your flexibility? The nervous system of mammals is very complex. For most major actions in the body the brain must decide what movement or action must be taken, the nerve impulses must be transmitted out of the brain, down the spinal cord and out to the intended receiver. Then when the action is carried out the impulse must return back the reverse pathway to tell the brain it was completed and start the next process. This is the path for any brain-controlled, conscious, impulses. Although it takes a lot of words to explain, it is really a very rapid process. There are many processes in the body that do not require direct thought to complete. The heart functions, breathing, metabolic processes, disease fighting and many other autonomic processes happen automatically in the body. The body uses signals to increase, decrease, or maintain many of these actions. If the carbon dioxide levels in the body begin to rise, the autonomic nervous system, through acid/base thermostats, calls for an increase in respiratory rate. Another automatic response by the nervous system is the reflex. The body reacts in a predetermined way based on specific stimulus. This may be a practiced response or a pre-programmed one. The stretch reflex is one of those responses. What is the Stretch Reflex? The stretch reflex; which is also often called the myotatic reflex, knee-jerk reflex, or deep tendon reflex, is a pre-programmed response by the body to a stretch stimulus in the muscle. When a muscle spindle is stretched an impulse is immediately sent to the spinal cord and a response to contract the muscle is received. Since the impulse only has to go to the spinal cord and back, not all the way to the brain, it is a very quick impulse. It generally occurs in 1-2 milliseconds. This is designed as a protective measure for the muscles, to prevent tearing. The muscle spindle is stretched and the impulse is also immediately received to contract the muscle, protecting it from being pulled forcefully or beyond a normal range. The synergistic muscles, those that produce the same movement, are also innervated when the stretch reflex is activated. This further strengthens the contraction and prevents injury. At the same time, the stretch reflex has an inhibitory aspect to the antagonist muscles. When the stretch reflex is activated the impulse is sent from the stretched muscle spindle and the motor neuron is split so that the signal to contract can be sent to the stretched muscle, while a signal to relax can be sent to the antagonist muscles. Without this inhibitory action, as soon as the stretched muscle began to contract the antagonist muscle would be stretched causing a stretch reflex in that one. Both muscles would end up contracting simultaneously. The stretch reflex is very important in posture. It helps maintain proper posturing because a slight lean to either side causes a stretch in the spinal, hip and leg muscles to the other side, which is quickly countered by the stretch reflex. This is a constant process of adjusting and maintaining. The body is constantly under push and pull forces from the outside, one of which is the force of gravity. Another example of the stretch reflex is the knee-jerk test performed by physicians. When the patellar tendon is tapped with a small hammer, or other device, it causes a slight stretch in the tendon, and consequently the quadriceps muscles. The result is a quick, although mild, contraction of the quadriceps muscles, resulting in a small kicking motion. Anatomy involved The muscles are attached to tendons, which hold them to the bone. Muscles have tendons at each attachment. At the attachment of the muscle to the tendon is a muscle spindle that is very sensitive to stretch. The motor neurons that activate the muscles are attached here as well. These are considered lower motor neurons. When they are stimulated they can cause the muscle to contract. This frees up the upper motor neurons and other portions of the central nervous system for more important functions. The motor neurons travel from the spinal cord to the muscle and back again in a continuous loop. Conscious movement comes from impulses in the brain travelling down the spinal cord, over this loop, and then back to the brain for processing. The stretch reflex skips the brain portion of the trip and follows the simple loop from muscle to spinal cord and back, making it a very rapid sequence. The gamma efferent cells in the loop work to keep the muscles ready for the stretch reflex, even when inhibited or contracted. This is important because if the muscle is working against a load and shortening during contraction and an additional load is added, the muscle recognizes the stretch immediately and can compensate with a stronger contraction. This also protects the inhibited antagonist muscles from being injured from excessive stretching. What causes it? The stretch reflex is caused by a stretch in the muscle spindle. When the stretch impulse is received a rapid sequence of events follows. The motor neuron is activated and the stretched muscles, and its supporting muscles, are contracted while its antagonist muscles are inhibited. The stretch reflex can be activated by external forces (such as a load placed on the muscle) or internal forces (the motor neurons being stimulated from within.) An example of the former is a person holding an empty tray in their outstretched arm and then having a plate of food set on it. The stretch reflex would kick in to keep the tray at the same height and balanced. An example of the latter would be the shivering of a cold muscle. The motor neurons are stimulated from an internal “stretch” to warm the muscles. Any abrupt, forceful stretch on the muscle causes the stretch reflex to fire, in a healthy person. Delays in or absence of the stretch reflex are signs of possible neurological or neuromuscular compromise. What to Avoid When Stretching? Many people have never learnt how to stretch properly. Maybe you have done this yourself: You watch other people stretching in the gym and try to imitate what you see. But who is to say that the person you are watching is doing it right? Here are some of the most common mistakes made while stretching: Bouncing. Many people have the mistaken impression that they should bounce to get a good stretch. Bouncing will not help you and could do more damage as you try to push too far beyond the stretch reflex. Every move you make should be smooth and gentle. Lean into the stretch gradually, push to the point of mild tension and hold for a few seconds. Each time you will be able to go a little further, but do not force it. Not Holding the Stretch Long Enough. If you do not hold the stretch long enough, you may fall into the habit of bouncing or rushing through your stretch workout. Hold your stretch position for at least 15 to 20 seconds before moving back to your original position. Stretching Too Hard. Stretching takes patience and finesse. Each move needs to be fluid and gentle. Do not throw your body into a stretch or try to rush through your stretching routine. Take your time and relax. Forgetting Form and Function. Think about your sport or activity. Which muscles will you be using? A stretching routine for a marathon run will be very different from a routine for an hour of lifting weights. Pay attention to the muscles you will need to use in your program and make sure your form for each stretch is attained properly. Consider the range of motion you will be putting that particular muscle through. The whole point of stretching is getting your muscles accustomed to moving through a specific range of motion, so if the muscle is not used to going that far, you may end up with an injury. So, to avoid the stretch reflex and potential damage to your muscles and joints, avoid pain. Never push yourself beyond what is comfortable. Only stretch to the point where you can feel tension in your muscles. This way, you will avoid injury and get the maximum benefits from your stretching. Stretching is one of the most under-utilized techniques for improving athletic performance and getting rid of those annoying sports injuries. Don’t make the mistake of thinking that something as simple as stretching won’t be effective.

Efitnessacademy.com was established in 2004 and since then the company has grown tremendously.  EFA is currently training and consulting with some of the top pro and amateur athletes in sports. Sincerely, Greg DiRenzo, CPT EFitnessAcademy

The importance of fluids in sports nutrition is, thankfully, beginning to become more and more recognized. Comprehensive research is being carried out in such areas as the amount of fluid lost during various types of exercise, and the optimal composition of sports drinks for use before, during and after exercise.

Too often, of course, participants in different sports are looking for an ergogenic aid to enhance their performance, ignoring the fact that if they paid more attention to proper nutrition it would do far more for them than any artificial stimulant. This should be the priority of all athletes and coaches.

And fluids are a vital part of proper nutrition. Whether you’re an elite marathon runner, rower, cyclist, dirt bike racer or simply work out a couple of times a week in the local health club, it is a virtual certainty that some sort of fluid replacement will improve your performance. Here are two important points to bear in mind. First, get rid of the idea that you only need to think about sports drinks on event or race day. Correct fluid replacement is essential for training just as much as competition, although more attention tends to be given to the latter. If you are going to use sports drinks in competition, it is imperative that you have tried them out in training first because some drinks cause stomach upsets in the uninitiated.

Second, it is wrong to think that you only need to drink on extremely hot days when you have become a little thirsty – you need to drink whatever the temperature. Yes, on a hot day if you wait until you are thirsty the chances are you are already on the way to becoming dehydrated, with potentially disastrous consequences for your workout or competition.

Why you need to take in fluids:
When you exercise, many metabolic reactions take place in order to produce the energy needed for muscular contractions. One of the by-products of these reactions is a large amount of heat. This means that if you are exercising for a long time at moderate to heavy intensity your heat production is going to be considerable. You may not think this is a problem until you remember that the body temperature has to be kept within a very narrow range. When you are exercising the extra heat has to be lost somehow and this is done by a variety of mechanisms, the most effective of which is, of course, sweating.

The problem with sweating is that after a while you are in danger of losing of losing a considerable plasma volume from your circulatory system and this will certainly impair your performance. It is well-documented that a loss of fluids equating to just 2% of your body mass will have a very detrimental effect on performance. Identifying how much fluid you actually lose is not always easy, but the best method is to weigh yourself before and after exercise. I need hardly remind you that excessive fluid losses in very hot environments can even lead to death.

Such risk of fluid loss is not confined to marathon runners and cyclists but can occur in most sports, especially those involving high-intensity intermittent exercise or during gym workouts. The point I’m making is that, although you must pay special attention to fluid replacement in a warm environment, it is also possible to lose fluid in a cool one if you are working hard or long enough.

NJ Motocross contributor Greg Direnzo was recently interviewed by MXPTV’s Matt Wozney.

Read all about it at the link below.

Greg Direnzo Interview

Post-exercise nutrition is a vital aspect of recuperation for any  athlete, but especially during multi-day competitions or after  hard training.  Although there’s plenty of evidence that a post- exercise high-carbohydrate diet can improve recovery, the  evidence that a high-protein diet can similarly aid recovery is, at  best, equivocal.  However, scientists from New Zealand have  examined the effect of post-exercise dietary protein content imposed over a high-carbohydrate background on subsequent  performance and come up with some intriguing results.  Twelve cyclists completed three high-intensity rides over four days as follows: day 1 comprising of a 2.5-hour high-intensity  ride; days 2 and 4, comprising of repeated sprint performance  tests, 15 hours and 60 hours after the initial session respectively;  day 3 as a rest day.

During a 4-hour recovery on days 1 and 2, the cyclists  ingested one of two diets:
1-Protein-enriched – 1.4 grams per kilo per hour of carbohydrate,
0.7 grams per kilo per hour of protein and 0.26 grams per kilo  per hour of fat.
2-Control – 2.1 grams per kilo per hour of carbohydrate, 0.1
grams per kilo per hour of protein and equal fat.

At all other times, the cyclists ingested a standardized high- carbohydrate diet.  A number of assessments were made during the study including muscle growth/breakdown (by measuring nitrogen balance), the degree of muscle stress and inflammation (by cortisolandcytokines), skeletal-muscle membrane disruption
(by creatine kinase), and damage from oxidative stress (by malonyldealdehyde).
The results showed that although means print power was not  clearly different on day 2, on day 4 it was 4.1% higher in the protein-enriched condition relative to control. Moreover,  overnight nitrogen balance was positive in the protein-enriched  conditionon day 1 (indicating muscle growth) but negative in the  control condition. The effects on oxidative stress, inflammatory  markers, and cortisol were considered in onclusive or trivial.  The researchers concluded that a delayed performance benefit
(at 60 hours) was observed following protein-enriched high- carbohydrate ingestion; these findings suggest that athletes  involved in several consecutive bouts of hard exercise over a period of a few days could benefit from an increased protein intake.  Appl Physiol Nutr Metab 2008;33(1):39-51

Numerous studies have shown that ingesting carbohydrate before and during exercise in the form of a drink can improve exercise performance.  This is because it helps to maintain blood glucose levels and spares stored carbohydrates in the muscles (glycogen).  However, as well as drinks, there are also other forms of carbohydrate supplementation, notably gels and ‘jellybeans’, but, to date, there’s been little data available on just how effective they are compared to carbohydrate drinks.  To endeavor to shed some light on this issue, Californian scientists have carried out a study examining the effects of four treatments in 16 athletes who first cycled at 75% of VO2max for 80 minutes before immediately completing a 10 km time-trial at maximum pace.

The four test conditions were as follows:
·         carbohydrate drink;
·         carbohydrate gels;
·         carbohydrate sports beans;
·         water(control condition).

In each of the carbohydrate treatments, which were given randomly before, during and after exercise, the subjects each consumed identical amounts of carbohydrate (0.6g of carbohydrate per 2.2 lbs of bodyweight per hour).  The researchers then recorded the effects of the different treatments on blood glucose levels and time-trial performance.

The results showed that the carbohydrate supplements all maintained significantly higher levels of blood glucose than the water treatment (5.7 mmol/L for sports beans, 5.6 mmol/L for sports drink, 5.7 mmol/L for gel, and 4.6 mmol/L for water) but that there was no significant difference between carbohydrate treatments.  Moreover, the 10 km time-trial results for the carbohydrate treatments were significantly faster (17.2 minutes for sports beans, 17.3 minutes for sports drink, and 17.3 minutes for gel) than water, where the average time was 17.8 minutes. But once again, there was no significant difference between carbohydrate treatments.

On the basis of this study, therefore, it seems that what matters is whether or not you use carbohydrate supplementation-not what in what form you ingest it!

Each day we receive questions about training. So I’ve taken those questions that we hear the most and answered them in a little different format.

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“Lactic acid” in endurance sports – motocross: myths, legends and reality.

Most endurance athletes, in this case motocross athletes still believe that lactic acid is released during hard or unaccustomed exercise and that this is what limits performance, as well as being the cause of stiffness and “arm pump.” Neither is correct. But not even is the terminology of “lactic acid”. Read more