Monday, June 22, 2009
Many endurance athletes such as runners, triathletes and cyclists will experience muscle cramps at some point during their training or racing. Using a definition from Dr. Martin Schwellnus a cramp is "a painful, spasmodic, involuntary contraction of skeletal muscle that occurs during or immediately after exercise"(1). While most athletes understand what a cramp feels like there is much confusion as to what causes cramps and how they can be prevented.
Dating back to the 1930s a theory was put forth that dehydration and electrolyte depletion were the primary causes of exertional cramps. This is still a popular theory that has come under fire recently. In 1996 Manjra, Schwellnus and Noakes did a study of over 1300 marathon runners and found the following criteria to be primary risk factors associated with muscle cramps during exercise:
* Older age
* Longer history of running
* Higher body mass index
* Shorter daily stretching time
* Irregular stretching habits
* Family history of cramping
They found no evidence of a large electrolyte imbalance in runners with cramps. Nor was dehydration deemed to be a causative factor. Other studies done throughout the 1980s and 1990s came to similar conclusions.
Schwellnus and Noakes put forth the new theory that abnormal spinal reflex activity is the real culprit behind muscle cramps. In other words, muscle fatigue leading to abnormal functioning at the spinal level of the muscle contraction mechanism is the root cause of muscle cramping during activity.
Receptors called muscle spindles cause muscles to contract when they are stretched. Other receptors called Golgi tendon organs (GTO) cause muscles to relax when they are contracted. Both types of receptors are needed to help protect muscles from over-stretching and over-contracting, respectively. These receptors act on muscles by sending an electric signal to the appropriate motor neuron, which is located in the spine. During a normal contraction, signals from both receptors are in balance. According to the theory, when a muscle fatigues the activity of the muscle spindles increases (causing a contraction) and the Golgi tendon organ activity is inhibited (no relaxing) leading to a muscle cramp.
They also cite another factor that contributes to cramping. Golgi tendon organ activity is also limited when a muscle contracts in its shortest position (also called the inner range). Muscles that are the most prone to cramps are those that cross two joints. Examples of such muscles are the hamstrings, gastrocnemius (one of the calf muscles) and rectus femoris (the longest of the quadriceps muscles). The hamstrings span the hip and knee, the gastrocnemius spans the knee and ankle and the rectus femoris crosses the hip and knee. During exercise these two-joint muscles are often contracted in their shortened position leading to less tension in their tendons as well as less activity of their GTO.
In their study, Schwellnus et al had runners list conditions they associated with cramps, which were as follows:
* High intensity running (racing)
* Long duration of running
* Subjective muscle fatigue
* Hill running
* Poor performance in the race
From this list it's obvious that conditions leading to premature muscle fatigue are linked to cramping. They also found that poor stretching habits seem to increase risk of cramping. The reasoning behind this is that irregular or not stretching the muscles "could lead to an exaggerated myotonic reflex, thereby increasing spindle activity."(1)
Some other explanations have also been offered as to what causes muscle cramps. Poor posture and inefficient movement patterns may cause the Golgi tendon organs to malfunction in a similar way as explained above.(2) The GTO cannot get the muscle to relax and a cramp begins.
Another theory offers that carbohydrate depletion may also cause muscle cramps.(2) This ties in with the abnormal spinal reflex theory as muscle fatigue is thought to play an important role in developing cramps. Carbohydrates are stored in the muscles as glycogen and used for energy during activity. Fully "topped up", a human being has enough glycogen stores to last for about 2 - 2.5 hours. If you run out then your muscles fatigue, your nervous system begins to malfunction and you get fuzzy, light headed and unable to think clearly; a condition athletes typically refer to as "bonking". That is why it is so important to take in adequate food during long distance/duration events.
Finally there is the theory of electrolyte imbalance. Dr. Bill Misner offers a thorough explanation in his article, "Muscle Cramps: Dealing with Heat Stress During Endurance Exercise".(3) While there is certainly more debate as to the role electrolyte imbalances may play in muscle cramps a proper level is still needed to perform well during events.
How to Prevent Muscle Cramps
Having some idea of why and how muscle cramps occur the $64,000 question is how to prevent them. Based on the major theories discussed take the following precautions:
* Train adequately for the conditions (pace, terrain, temperatures, duration, etc.) you plan to compete in
* Follow a regular stretching program (read my article on stretching for recommendations on how to stretch properly)
* Work on correcting any muscle imbalances or incorrect movement patterns; develop an efficient technique required for your sport
* Take in enough carbohydrates before, during and after your event; the amount will vary among individuals but aim for 250 - 400 calories per hour during the event
* Hydrate properly during the event, especially events lasting longer than 3 hours; using a sports drink and not just water will give you the electrolytes you need; again this will vary among individuals and conditions but aim for 125 - 250 ml every 10 - 20 minutes
What to Do If You Cramp
If you do cramp there are a few things you can try:
* Slow down and lower the intensity of the activity
* Stretch and try to relax the affected muscle(s)
* Apply pressure to the affected muscle group(s) to get the muscles to "release"
None of these are guaranteed to relieve a cramp and in these cases all you can do is grin and bear it.
Stay fit, stay healthy!
Curb Ivanic, CSCS
1. Schwellnus, Marti P., "Skeletal Muscle Cramps During Exercise", Physician and Sportsmedicine, 1999; 27 (12)
2. Friel, Joe; "Muscle Cramps", 2000
3. Misner, Bill, "Muscle Cramps: Dealing with Heat Stress During Endurance Exercise"
4. Noakes, Tim, Lore of Running (Third Edition); Leisure Press; Champaign, Illinois; 1991
Friday, June 12, 2009
What to Do When Fitness Injury Strikes
WebMD Weight Loss Clinic-Feature
You've reduced your calories and increased your activity and finally, the weight loss is starting to show. Then one unsuspecting day you don your workout clothes, tie on your sneakers -- and the next thing you know, you're yelping in pain.
Experts say a workout injury can happen to anyone, regardless of experience or conditioning.
"A pulled muscle, a strained back, a turned ankle, a shoulder sprain -- it can happen in the blink of an eye, usually when you least expect it," says Todd Schlifstein, DO, clinical assistant professor of physical medicine and rehabilitation at New York University Medical Center.
According to sports medicine specialist Robert Gotlin, DO, the most vulnerable areas for pulls and strains are the hamstring and thigh, followed by leg or calf muscles.
If you're a beginner exercising to lose weight, the risk of injury may be even greater, with hot spots that also include knees and ankles.
"If you are overweight, the most common injury is a sprain occurring in either the ankle or the kneecap," says Gotlin, director of orthopaedic and sports rehabilitation at Beth Israel Medical Center in New York. This problem often occurs when surrounding muscles are weak due to a lack of exercise, he says.
"The more out of shape you are when you start to work out, the greater your risk of injury, particularly if your muscles are weak," says Gotlin.
Pain vs. Soreness: Know the Signs
Even if you're already in good shape, experts say problems can occur if you overuse any one set of muscles. To keep this from happening, ease into the activity slowly and never skip warm-ups.
"For example, take five minutes out to stretch your muscles before jumping on that treadmill or bicycle, and don't push yourself to the point of pain -- even if you have done the routine before," says Schlifstein.
Some more advice: Stop immediately if you do feel pain, and rest for a day. If pain begins when you do the same motion again, says Schlifstein, it's a sure bet you've got an injury.
But how do you know you've got an injury and are not just sore from working out?
"Soreness usually shows up one or two days after you work out, and does not usually occur while you are actually doing the activity," says Rich Weil, MEd, CDE, an exercise physiologist at St. Luke's-Roosevelt Hospital in New York and consultant for the WebMD Weight Loss Clinic.
If you try to work out when you're feeling sore, the pain usually subsides after 10-15 minutes of activity, Weil says. Not so when an injury is involved.
"Pain related to an injury gets worse when you are working out," says Schlifstein. "That's when you know it's time to stop and listen to your body."
Tuesday, June 2, 2009
The options include sports drinks, energy drinks, and just regular water.
We all know that when we work out, it's important to stay hydrated. Something we may not be so clear on is what exactly we should drink when we exercise.
Ordinary water, of course, is the classic choice. But with store shelves everywhere full of sports drinks, energy drinks, and various flavored and fortified waters, what's an exerciser to do?
Experts say it all depends on your taste -- as well as the length and intensity of your workouts. Here's a look at how the various drinks measure up.
Flavored or Unflavored?
When I'm really thirsty, the only thing that hits the spot is good old H2O -- preferably cold. But that's just me.
Are you someone who will drink more if your drink is flavored (and there are plenty of you out there)? Then you're better off drinking whatever ends up helping you drink more when you exercise. The bottom line is hydration.
The American College of Sports Medicine recommends flavored drinks when fluid replacement is needed during and after exercise to enhance palatability and promote fluid replacement.
And how do you know when fluid replacement is really needed?
"Exercising 1.5 hours to three hours is long enough to warrant fluid replacement due to sweat losses," says Kristine Clark, Ph., FACSM, director of sports nutrition for Penn State University Park. "How much sweat is lost influences how much sodium and potassium are lost."
The longer you exercise and the more heavily you sweat, the greater the need for a sports drink to help replace these lost micronutrients, Clark says.
"A sports drink can do many great things to increase energy levels without the complications of digesting and absorbing a meal," says Clark.
Sports Drinks and Exercise
Basically, a sports drink offers your body three things it might need before, during, or after vigorous exercise:
* Hydration. The American College of Sports Medicine recommends that people drink about 17 ounces of fluid about two hours before exercise, to promote adequate hydration and allow time for the body to excrete any excess water. During exercise, they recommend that athletes start drinking early and at regular intervals in order to take in fluids at the rate they're losing them through sweating.
* Fuel. The carbohydrates found in sweetened sports drinks provide energy to help delay fatigue, Clark says. The Gatorade Co. says lab tests have shown that 6% carbohydrate (14 grams of carbohydrate per 8 ounces of water) is the optimal percentage of carbs for speeding fluid and energy back into the body.
* Electrolytes or Minerals. These are things like sodium, potassium, and chloride that athletes lose through sweat. When water goes out of the body, so do electrolytes. And when the body is losing lots of water (as during exercise), it makes sense that you need to replace electrolytes.
What About the Average Exerciser?
So what if you're just a "weekend warrior" when it comes to tough workouts? Or an avid exerciser who's not quite of athlete standing? Do you really need a sports drink when you exercise?
The answer, it seems, lies in how much you're sweating.
The American College of Sports Medicine says that during exercise lasting less than one hour there's little evidence of any difference in performance between exercisers who drink beverages containing carbohydrates and electrolytes, and those who drink plain water.
And, according to Clark, someone exercising 1.5 hours in a cool environment (who is probably not sweating much) is more in need of fluids or water than electrolytes.
The ABCs of Vitamin Water
I totally get adding electrolytes to drinks to help your body recover from vigorous exercise, but vitamins? It's still best to get vitamins and minerals naturally from foods and beverages -- like vitamin C from citrus and dark leafy green vegetables, and calcium from dairy products.
"Athletes will not need vitamin and mineral supplements if adequate energy to maintain body weight is consumed from a variety of foods," the American Dietetic Association and American College of Sports Medicine say in a position paper on nutrition and athletic performance.
But if you really like the idea of vitamin water, here are some things to think about:
* Whether alternative sweeteners are added. Many experts believe that even alternative sweeteners should be consumed in moderation, especially in children.
* Whether you'll be taking in too many vitamins. Most of the vitamins added to vitamin water are water soluble (like vitamin C, B vitamins, etc.). This makes it seem like any excess consumed can just pass out through the kidneys. This is true -- but that doesn't mean large amounts of water-soluble vitamins are entirely harmless. High amounts can affect the absorption or utilization of other nutrients. It's also possible that passing large amounts through the kidneys could cause problems.
* Whether you might be just as happy with dressed-up regular water. You can flavor it with lemon, lime, orange, or a strawberry or two. Green tea comes flavored naturally these days, too. This can be a different but healthful way to drink water once a day, too.
Source: By Elaine Magee, MPH, RD
WebMD Weight Loss Clinic - Expert Column