ENDURANCE ACTIVITIES:
Cramping and Endurance Exercise
David Lapoff, ACSM HFI, CSCS
Lion's Fountain Personal Training Honeoye Falls, New York
CRAMPING IS A PROGRESSIVE or acute involuntary contraction of a muscle that
is usually painful, sometimes exquisitely so. The pain can destroy performance,
sometimes for several days after the incident. Strategies for achieving top
performance have to include strategies to reduce the frequency and intensity of
cramping. Common victims of cramping include the calves, hamstrings, and
diaphragm/abdominal wall cramp commonly referred to as the "stitch."
There are 2 theories of muscle cramping. The so-called South African theory
holds that poor exercise technique results in a lack of stimulation of the golgi
tendon organ (GTO) allowing the muscle to progressively tighten into a spasm (5
, 6 , 8 ). Recall that the GTO is a proprioceptor in the muscle tendon that
detects excessive tendon tension and relaxes the muscle. This counters the
action of the muscle spindle that tightens the muscle when it is rapidly
stretched. The other theory suggests progressive sodium losses from sweating (or
limited intake) make nerves hyperexcitable causing the muscle to spasm (2) .
There is good observational data from both camps, which makes this author
believe (as with most either/or questions) that the truth is probably a
combination of both causes.
Morton and Callister studied the abdominal stitch (4) and found frequency and
intensity to be unrelated to the fluid or food consumed. Rather it is believed
that diaphragmatic tugging on the abdominal wall provokes the spasm. This seems
likely because tugging may provoke the stretch reflex of the abdominal muscles.
Another phenomenon described by athletes as a "stitch," is a trapped
air bubble in the gastrointestinal tract. Sloppy drinking during an event or
training can cause the swallowing of air into the stomach. Arising from the
heightened excitement of competition, it is relieved quickly by a position
change (e.g., lying down) allowing the air bubble to escape.
Because avoidance of cramps is the best defense, considering the theories of
their development gives us an insight into how to prevent and deal with them. If
we subscribe to the "South African theory," then we should focus the
client on the portion of the sport skill that lengthens the at-risk muscle when
they feel the cramp beginning. (e.g., heel strike with pronounced dorsiflexion
for the gastrocnemius, butt kick for the quadriceps, increased stride length for
the hamstring).
If sodium losses are the suspected cause of the cramping, attention must be
paid to the athlete's intake of sodium both habitually and during the endurance
event. Plain water is therefore not the beverage of choice during a long
endurance event. The hydration plan for the athlete should include sufficient
calories and electrolytes to replace those lost to exercise (1).
Measuring an athlete's sweat rate is the first place to start when concocting
a hydration solution. Once the quantity of sweat loss is known then the losses
of sodium and other electrolytes can be estimated. Normative sweat contains
approximately 35 milliequivalents of sodium. This corresponds to approximately 2
g of NaCl dissolved in a liter of water.
Cystic fibrosis (CF) is a risk factor of which trainers should be aware.
Approximately 1 in 20 Caucasians possess 1 CF gene. This can lead to sweat with
higher concentrations of both sodium and chloride. Seventy to eighty
milliequivalents is not uncommon for these people (2) . Signs that this may be
an issue for a client include caking of salt on the skin or sweat that burns the
eyes. Consider referring these clients to their physician for testing. A
hydration solution this salty may be unpalatable and so the use of salt tablets
may be helpful in this case. It is most imperative that profuse sodium excreters
do not use plain water as their hydration fluid because this can lead to
hyponatraemia, which can be serious enough to be fatal.
Several approaches for relieving the stitch are put forward. Noakes
recommends changing the stride/breath relationship so that the diaphragm is in a
different relative position during the stride cycle. This presumably changes the
location of tugging and reduces the stimulus to cramp. Noakes also recommends
diaphragmatic ("Belly") breathing to prevent the development of the
stitch (7) . This author has had positive results with focused training of the
abdominal muscles, particularly the obliques, reducing the frequency and
intensity of abdominal stitches.
Abdominal "cramps" due to air ingestion can be avoided by
concentrating on avoiding air intake while drinking and consciously attempting
to evacuate any swallowed air immediately after taking a drink.
When is a cramp not just a cramp? One dangerous condition for which a
responsible trainer or coach should watch is the sickle cell trait. Those with
sickle cell trait (1 in 12 with African or Caribbean heritage, 1 in 10,000 in
Caucasians) may not have the symptoms of sickle cell anemia but under
high-intensity exercise conditions experience sickling, impeding blood flow. The
result is exquisite pain dropping the athlete to the ground. These episodes
usually occur at the beginning of the workout during a sustained, high-intensity
effort and do not include a loss of consciousness. Keep this athlete well
hydrated and arrange for him/her to see a doctor immediately. This kind of event
can lead to rhabdomyolysis (muscle damage), which can cause kidney failure and
death. To minimize this possibility, avoid sustained maximal efforts (e.g.,
800-m wind sprints) and keep the athlete well hydrated (3) .
Cramping is a performance-sapping, painful event for an athlete. The diligent
coach or trainer will help the athlete develop strategies for avoiding them.
Electrolyte replacement and scrupulous exercise technique are the keys to
avoiding skeletal muscle cramping. Abdominal wall strength, breathing, and
drinking techniques all serve to affect the frequency and intensity of
exercise-related abdominal pain.
References
1. Bergeron, M.F. Sodium: The Forgotten Nutrient. Sports Science Exchange.
V13:(3) Gatorade Sports Science Institute. 2000.
2. Eichner, E.R. Cramps-management and prevention. Presented at Ironman
Sports Medicine Conference. Kailua-Kona, HI. 2001.
3. Eichner, E.R. Rhabdomyolosis-the spectrum the spectre. Presented at
Ironman Sports Medicine Conference. Kailua-Kona, HI. 2001.
4. Morton, D.P., and R. Callister. Characteristics and etiology of
exercise-related transient abdominal pain. Med. Sci. Sports Exerc.
V32:(2)432-438. 2000.
5. Noakes, T.D. Fluid and Electrolyte Disturbances in Heat Illness:
Implications for Emergency Management. Trauma Emerg. Med. June/July 1998.
6. Noakes, T.D. Heat disorders in athletes. Presented at Ironman Sports
Medicine Conference. Kailua-Kona, HI. 1998.
7. Noakes, T.D. The lore of running. Human Kinetics. Champaign IL. 1991. pp.
194-195.
8. Schwellnus, M.P. Skeletal muscle cramps during exercise. Physician Sports
Med. V27:(12) 1999.
David Lapoff is a personal trainer and is certified by the American College
of Sports Medicine and the Aquatic Exercise Association.
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