Medical
Advice for enjoying the Six Foot Track!
Dr
Jonathan King, Sports Physician.
Although I
have run about twenty marathons and ultramarathons, I discovered that the Six
Foot Track poses unique challenges.
Since my
last Six Foot Track run in 2004, I have been involved with the medical coverage
of the race. My appreciation of the event has shifted to managing problems that
runners face when doing the event.
A mental
image of the run and breaking up the Track into sections will assist with
pacing, and enjoying the event (!)
The
start can be
hectic, with runners scrambling to get good position before descending the
steps to the valley floor. If you are a slower stair descender it is better
that you stay towards the back of the pack initially.
Runners
should be in single file when descending the stairs. This requires
concentration as a stumble or misplaced step can lead to a sprained ankle (or
worse). There is ample time to pass others on the wider section on the
The first
fifteen kilometers to the Coxs river is enjoyable and this can be
considered a warm-up prior to the hills!
Novices and
weaker hill climbers should consider walking the steeper hills to conserve
energy along the course. The section from the
The main
hills are from Cox’s river (15.5km) to Mini Mini Saddle (20km), Alum
Creek (22km) to Pluviometer (26km), and a less steep but long section from
the Pluviometer to the Deviation (34.7km).
From the
Deviation to Kiaora Hill the course undulates until the final descent to Caves
House. The final 5km can be treacherous especially if you have “jelly
legs”, tired quadriceps muscles and a slippery scree-like descent to Carlottas
Arch.
Potential
problems
Because of
the requirements to qualify for the Six Foot Marathon, I expect that (most)
runners will have had time and experience to sort out problems associated with
running.
I list a
few major problems that may slow you down:
Muscle
Cramps, or
specifically “exercise associated muscle cramps (EAMC)” may occur even in
experienced runners.
We need to
be sure that we’re talking about the same thing- “involuntary, painful, sudden
contraction of skeletal muscle”, which is usually quadriceps, hamstring or calf
muscles. This is not to be confused with a feeling of “muscle tightness” that
many runners have.
In a
general sense there are many causes of muscle cramps. Generally speaking, if
one has recurrent cramps (without running) then one has to exclude causes that
may be due to problems of muscle (e.g. muscle enzyme disorders), nerve (e.g.
central or peripheral nerve disorders), cardiovascular (e.g. hypertension) or
endocrine (hypothyroidism). Medications such as antihypertensives, asthma
inhalers, and hormones, such as the oral contraceptive pill have also been implicated
in muscle cramps. These factors are unlikely to play a role in Six Foot
runners.
There have
been a few theories about the cause of EAMC:
·vLow serum sodium levels. There has been a long-standing
belief that depletion of salt through sweating is the cause of this problem.
There have been a number of studies in the late 1980’s that related EAMC with
low sodium concentrations.
·vDehydration.
Many years ago it was noted that miners and steamship workers developed
muscle cramps. Rapid dehydration (e.g. diarrhoea, or profuse sweating) has also
been noted to result in muscle cramps.
·vLow calcium, or magnesium levels have also been implied in the cause
of muscle cramps.
Most
runners are aware of the above, and some resort to using salt (sodium), and
magnesium supplements, as well as increased drinking to avoid
dehydration-related problems.
However
some runners still have muscle cramps despite the above precautions.
A recent
study by Schwellnus et al (2004) examined 72 runners before and after the Two
Oceans Marathon in
Current
theory
In fatigued
muscles that are contracting and shortened (e.g. in quadriceps muscles) there
is increased electrical activity in the muscle resulting in cramping.
The
scientific explanation is that there is increased stimulation from muscle
spindles (a specialized muscle structure that provides sensory input about rate
and degree of muscle stretch and assists with limitation of muscle stretch),
and decreased
inhibition impulses from Golgi tendon organs (a sensory structure at
the muscle-tendon junctions that tells the brain about the tension in the
muscle, and helps regulate the muscle tension).
It is
thought that other factors contributing to EAMC are:
·vOlder runners
·vFaster speeds
·vLonger running history
·vIrregular stretching
·vFamily history
·vContraction of muscles that cross
two joints (hamstrings, quadriceps, gastrocs)
Prevention
of muscle cramps
At the risk
of stating the obvious, there is no
substitute for training. Because the Six Foot Marathon is on hilly bush
terrain often in the heat (high 20’s Celsius), these are the conditions under
which you should train.
Regular stretching of the quads, hamstrings, and calf muscles may
assist with flexibility, although there is no hard evidence that this prevents
EAMC.
Maintain hydration during the race. Do not attempt to replace all the fluids that (you assume) you
have lost during the race. I am wary about being prescriptive about fluid
replacement during exercise as there are large variations in sweat rate between
individuals and for even the same person.
Taking salt
tablets does not guarantee that you will not develop EAMC! It is not possible
to be prescriptive on amounts, as there is variation in salt intake and sweat
rates. There may be a daily variation from 3g to 20g in salt intake, depending
largely on personal preference. Similarly sweat rates vary according to
intensity of exercise, environmental conditions (heat and humidity), gender,
body size, and level of metabolism. During exercise sweat rates have been
measured between 0.5L to 2L per hour.
It is very
difficult (and potentially dangerous) to try to replace all water and
electrolyte lost in sweating by drinking or eating during the run. For example,
many runners will find it difficult to replace 1L of water in an hour when
running in the heat. During moderately intense exercise, blood is diverted from
internal organs (including the stomach) to the skin to allow heat exchange and
sweating, and diverted to muscles to allow running. During intense exercise
gastric (stomach) emptying is reduced, and running with a full stomach can lead
to abdominal discomfort from the vertical bobbing up and down.
What to
do if you have EAMC
·vWhen you have muscle cramps you will
be forced to walk!
·vStretch the affected muscle group.
Hold the stretch for about 20 seconds.
·vDrink as much as thirst dictates.
·vEat a snack (e.g. energy bar/ gel,
fruit) while walking.
·vIf cramps continue despite the
above, massage of the affected muscle group will help.
·vWalk for about 5 minutes before
starting to run.
·vJog initially for about 1 km before
increasing pace.
Fluid
recommendations
I expect
that virtually all athletes are aware of the problems related to dehydration,
especially when exercising in the heat.
Before
sports drinks were available, marathon runners had variable access to water,
soft drink and snacks (e.g. fruit, sweets). Since sports drinks have become so
widely available, and are present at almost every fun run, marathon or
ultra-marathon, they are now the standard fluid replacement for runners.
From a
physiological point of view, sports drinks (containing sugar and salt) are
recommended for those exercising for more than an hour.
A major
sports drink manufacturer recommends that runners should aim to replace about
1L fluid for every hour of running. In 2001 the International Marathon Medical
Directors Association (IMMDA) recommended 400-800 mL/h fluid ingestion. This
recommendation protects smaller athletes from becoming overhydrated (and
hyponatremic), a problem that can be fatal.
It is not
the purpose of article to explain hyponatraemia, but this is defined as
abnormally low plasma sodium levels as a result of drinking excessive fluid
(water and/or sports drink during a marathon). This usually occurs in slower
runners who have access to fluids on the course).
Practical
recommendations (IMMDA,
2006)
1. Drinking according to thirst is the
body’s dynamic fluid calculator that protects from over and under drinking.
2. Athletes are advised to understand
their individualized fluid needs – for example during a known run and under
known ambient conditions (temperature, humidity, wind), note how much you
drink. Also take note of body cues such as thirst (indicating under drinking),
increased urination or weight gain (indicating overdrinking).
3. Athletes should explore, understand
and be flexible to their own fluid and energy (food) needs while training and
also during running events.
A practical
way of determining fluid loss from sweating:
1. Nude weight before a run (W1).
2. Run for an hour at race pace. Note
the temperature and humidity. Note amount of fluid consumed during the hour
(F).
3. Do not urinate during the run.
4. Nude weight after run (W2).
5. Sweat loss = W1 – W2 + F.
One should
NOT gain weight from drinking fluids during a run! This indicates fluid
retention and risk from over diluting the salt in the blood (hyponatremia).
This can be fatal!
In a
marathon runners should be able to tolerate 2% fluid loss (1.2 kg in 60kg
person; 1.6kg in 80kg). Therefore it should be safe to replace 98% fluid loss
in a marathon. For example a four hour marathon runner who sweats at 1L/hr may
safely replace 3.92L.
A recent
conference on exercise-associated hyponatremia(EAH) identified risk factors for EAH:
·vLow body weight
·vFemales
·vExercise 4 hrs (or more)
·vSlow pace
·vRace inexperience
·vExcessive drinking behavior
·vHighly availability of drinking
fluids.
If there
are a few risk factors, one can prevent EAH by dinking only according to
thirst, or by avoiding drinking at a rate more than one’s estimated hourly
sweat loss. Consuming salty drinks may not prevent EAH, although this may
reduce the severity.
Conclusion
For many
Six Foot runners, survival is the main objective. From a medical point of view
this means maintaining hydration and food (carbohydrate) supply, avoiding
cramps, dehydration and heat illness as well as staying on your feet at all
times!
The Six
Foot Track Marathon is much more than a standard (road) marathon and
preparation should be appropriate. Ideally one should train regularly in the
heat, learning as much as possible about one’s (physiological) response to
training. One should work out optimal fluid and feeding strategies during long
runs (25-30km), which should be on hilly bush trails. Even walking up long
hills is good training!
Despite
ones best efforts one could develop problems on race day. Knowing one’s limits
is essential for survival! If one develops problems such as muscle cramps,
vomiting, or extreme fatigue then walking and asking for assistance at an aid
station is a sensible option.
There may
well be a fine line between pushing to
one’s limits and pushing beyond one’s
limits! It often takes years of experience to read one’s body during prolonged
exercise, and it is a fantastic feeling when everything is going well. The pace
on the day depends a lot on the weather conditions, preparation, and how much
one is prepared to suffer!
Happy
training and I hope to not meet you on Race Day!
References
1. Byrne C et al. Continuous
thermoregulatory responses to mass participation distance running in heat. Med
Sci in Sports & Exercise. Vol 38(9) 803-810, 2006.
2. Hew-Butler T et al. Consensus
statement of the 1st International Exercise-Associated Hyponatremia
Consensus Development Conference,
3. Hew-Butler et al. Updated Fluid
Recommendation: Position Statement from the International
4. Schwellnus et al. Serum Electrolyte
concentrations and hydration status are not associated with exercise-induced
muscle cramps (EAMC) in distance runners. Br J Sports Med. 38, 488-492, 2004
5. http://www.usatf.org/groups/Coaches/library/hydration/USATFSelfTestingProgramForOptimalHydration.pdf
6. http://www.itsonthecourse.com/