Exercise requiring significant effort, either from high energy demands (low resistance, rapid contraction rate) or substantial muscle effort (high resistance, low contraction rate) is often associated with muscle pain or discomfort. No study has identified a single cause for this discomfort, although the fact that it occurs more quickly in a muscle with a limited blood supply suggests that the culprit is a product of muscle metabolism. In addition, as the ingestion of sodium bicarbonate will delay the onset of pain for any level of exercise, it is thought that the substance is acidic in character.
Lactic acid is considered the likeliest candidate although other metabolites such as pyruvic acid and ammonia have also been suggested. Based on the differing results in various papers in the literature, it is most likely that pain in the actively contracting muscle is multifactorial (ie related to a combination of substances) including the build up of acidic intermediate metabolites, ionic shifts at the cell membrane level (K, magnesium), and actual changes in the muscle cell proteins themselves. The fact that training will increase the level of activity at which discomfort first occurs indicates that the muscle cell can adapt to these factors.
It is interesting that the body also has a mechanism to deal with this discomfort. Endorphins, opiate like substances produced internally, are secreted into the central nervous system during endurance exercise and will alter the perception of pain during prolonged high intensity exercise. Thus we have a mechanism to warn of muscle overuse, and also one to suppress pain during prolonged exercise which may be beneficial in fleeing from dangerous situations.
Although conventional wisdom holds that taking aspirin before a ride will cut down on muscle pain during exercise, a study at the University of Georgia recently concluded that even at large doses (20 mg per kg or 4 standard aspirin for the average rider), aspirin did not delay the onset of muscle pain during exercise or reduce the perceived intensity when it occured.
DELAYED ONSET MUSCLE SORENESS (DOMS)
This is the soreness (stiffness) that begins 24 to 48 hours after exercise and peaking by 48 to 72 hours. It is most evident after "eccentric" muscle actions which involve actively resisting lengthening of the muscle as occurs in raising or lowering a weight, and indicate a high tension on muscle fibers and connective tissue as opposed to isometric or static tension activity. It is accompanied by a decrease in muscle strength, a reduced range of motion, and leakage of muscle cell proteins (creatine kinase, myoglobin) into the blood. These three findings indicate muscle damage (most likely related to minute tears and physical damage) as opposed to the buildup of metabolic byproducts during exercise, and muscle biopsies demonstrate muscle contractile fiber damage and an inflammatory response.
Generally DOMS is noted after unaccustomed eccentric exercise. And it does not appear that soreness from previous exercise increases the chance of further muscle damage. In fact the adaptive process of healing, even from microscopic injury with minimal pain, appears to have a significant protective effect on the development of muscle damage and soreness from subsequent exercise - the reason one should use a gradually progressive exercise training program.
In 1997, a small group of elite athletes with a combination of chronic fatigue and delayed onset muscle soreness were described. Muscle biopsies were abnormal and the authors speculated on the possibility of cummulative chronic injury which might interfere with performance.
MUSCLE CRAMPS It's not unusual to hear the following story:
"I entered my first mountain bike race (18 miles) and at mile 14, my thighs and right calve cramped up. This has happened before on long rides. I thought I trained enough, hydrated enough, and ate enough bananas, but I still cramped up and had to go real slow for the last 4 miles. It was sooooo frustrating. I have another race coming up next month but its only 12 miles but has steeper hills. What should I do? Do tights help reduce cramps? When I get them (cramps) should I massage the cramped area? Should I train the amount of miles of the race?"
Cramps are most common when you use your muscles beyond their accustomed limit (either for a longer than normal duration or at a higher than normal level of activity) - which explains why cramps are more common at the end of a long or particularly strenuous ride or after a particularly vigorous sprint. In fact cramps are among the most frequent complaint in marathon participants (18% in one study). In another study of cyclists competing in a 100 mile race, 70% of male participants experienced cramps (women, interestingly, had a rate less than half as frequent at 30%).
The pain is brought on by an intense, active contraction of the muscle cells themselves. Although cramps may occasionally be the result of fluid and electrolyte (sodium) imbalance from sweating, that is not universally the case as individuals involved in activities requiring chronic use of a muscle without sweating (musicians for example) will also experience cramps.
In one study of marathon runners, there were no differences in sodium or hydration levels between the 15 participants who developed cramps and the 67 who didn't. And although a low magnesium level can cause severe muscle cramping, another study of magnesium supplements in triathletes failed to show any benefits as far as cramping.
However, as is often the case when there is no consensus on etiology, you will find conflicting opinions as to treatment options. This is most likely related to the fact there are multiple causes i.e the actual cause may be different from one person to another, and even be additive in some, that is fatigue plus dehydration. Bill Misner, PhD starts off noting that "the etiology of a common exertional muscle cramp during the heat of summer is not agreed upon by research because of a multiple of biochemical aberrations that may result in neurophysiological failure", then reviews the convoluted physiology of muscle contraction, and concludes that "the single cause of muscle cramps is inconclusive to date." Unfortunately he then proceeds to give us a specific electrolyte formula to prevent cramps (unsupported by any controlled studies other than in exceptional circumstances).
There are 4 issues to be considered in the prevention of muscle cramps:
In a recent review, it was suggested that magnesium might be the most important of the electrolytes (after hydration was attended to). The following comments were eleicited by a comment that suggested calcium was the culprit.
If cramps do occur, gently stretching the affected muscle will give relief, and some authorities feel that stretching used prophyllactically will prevent cramps. Calf cramps can be relieved by standing on the bike and dropping your heel, while anterior thigh cramps can be stretched out by unclipping and moving your thigh backwards towards your buttocks. Although a number of medications have been suggested as treatments for muscle cramps (vitamin E, verapamil, and nifedipine to name a few) only quinine has been shown to be effective in scientifically controlled studies. But the high incidence of side effects limit its usefulness as a routine treatment.
My recommendations for those suffering from frequent muscle cramps?
The first question demonstrates the role training can play in prevention of cramps - even though it relates to the question of cramps in a non cycling event. (The answer was provided by an associate at my clinic.)
Q:I started cycling about 6 months ago and trained really hard this summer for a double century. In all the training and the race itself I rarely suffer from any muscle spasms. However since I started cycling I (may just be coincidence) get EXTREME spasms when I hike down hill. Hiking uphill doesn't bother me, but my quads and calfs literally freeze up after only 5-10 minutes of down hill hiking. It becomes so painful I can barely bend my leg. Last time I only hiked 1/2 mile and I thought they were going to have to carry me out. I've tried stretching before and it doesn't help. Within hours the spasms are nearly gone and by morning I feel fine. This probably sounds crazy, but I can't figure out how I can bike 200 miles and can't hike 1/2 mile.
A: Here's the somewhat technical answer: The ankle plantar flexors and quads act concentrically in cycling - that is they generate tension (fire) while shortening. Through the down stroke the ankle plantar flexes and the knee extends under the influence of the gastrocs, soleus and quads. At the bottom of the stroke and through the up stroke, the hamstrings are shortening too.
In walking down hill the opposite is true. Your friend is repeatedly letting himself down hill under the eccentric firing of the quads, plantar flexors and hamstrings. To keep from falling forward the hamstrings fire to keep the pelvis from rotating forwards. During stance phase the ankle dorsiflexes over the planted foot lengthening the plantar flexors and the knee flexes lengtheing the quadriceps muscles. A pack will change the equation in that it will greatly amplify the intramuscular tension and therefore the work performed by the muscle. Work that these muscles are not trained (training meaning the physiologic and anatomic adaptations to repeated work) to do.
And the short version: In terms of improving the situation the answer is really cross training - his muscles are well equipped for steady state aerobic concentric work at 90 to 110 rpm but not the greater intensity, near anaerobic threshold eccentric work of hiking down hill. I would bet that eight weeks of running including 20% speed/interval work will turn the problem around.
Q:I am 42 years old and I have been cycling for 19 years. I have one real problem that I can't seem to shake. CRAMPING. I have trained longer, harder, faster, further and taken every conceivable >concoction used, special supplements and the thing I have found that works the best although it does not work 100% is drinking Indian tonic water for the week leading up to the race. Am I right in saying that I am just one of those people prone to cramping or can I really do something about it. I must add that I have developed a strange ability to endure these cramps and ride through them only for them to reappear and literally bite me so hard I have nearly fallen off my bike. Kind regards. James.
A:Muscle cramps are probably multifactorial in origin - exercise beyond your limits (distance ridden or maximum levels of exertion), dehydration, electrolyte imbalance, etc. And age is a factor as well. I never cramped until I got into my 40s, and leg cramps are a common complaint of older patients of mine. Once you have corrected all the variables which you can control (age of course is not one) then I think it becomes a matter of learning the triggers and riding within your limits which are defined by trial and error (and may vary depending on how well you are trained at the time).
ADDITIONAL RESOURCES
Here is a link to further information on muscle cramps at Roadbikerider.com