Studies show that our bodies can process fats and carbohydrates normally up to 5,000 meters, so any loss below that elevation can be attributed to less than adequate intake.
When exercising for a decent length
of time (e.g. over 40 minutes), working at say 65% of your maximum
heart rate or at over capacity (average jogging), you burn up
instant muscle glycogen. You need to replace this muscle glycogen
or muscle fuel or else you will have tired muscles for the next
1-2 days. Obviously this is not quick recovery. To avoid this,
try to eat within 20 minutes of completing your work out (this
can be difficult if you are showering and taking a sauna etc.
at the gym) but eating within the next 30 minutes after exercise
when the body is still aerobically metabolizing and is in muscle
glycogen conversion mode will 'repay' the 'debt' of muscle fuel
and will quicken recovery so you will be ready to exercise again
the next day.
If you are planning on doing any big
days of exercise, keep eating small amounts frequently, approximately
every 40 minutes - 1 hour. This applies to water and electrolyte
drinks also. Electrolytes are necessary for proper muscle and
nerve functions, so electrolytes are very important for long days.
Even if you are not exerting yourself you will still use up a
lot of electrolytes over the course of a few hours. Mix in 1/2
a teaspoon of salt with 1 litre of water, if you expect to be
sweating. You can also combine this with electrolyte supplements
if you wish. Salty crackers (with avocado) are an ideal snack
food for long hikes.
PRACTICAL IMPLICATIONS FOR ATHLETES
| Diet: A high carbohydrate,
low salt diet allows for better adaptation and less risk of
"mountain sickness". Some people experience significant
decline in appetite and the resulting loss of muscle mass
may hinder performance. Iron is used to make hemoglobin and
the demand for making more red blood cells may require iron
supplementation -- especially in women and vegetarians. Megadoses
of vitamins are not helpful and are potentially dangerous.
| Fluids: Because mountain air
is cool and dry you can lose a lot of water so be sure to
maintain adequate hydration.
|Alcohol: It is best to avoid alcohol consumption
during the acclimatization period since it appears to increase
the risk of "mountain sickness".
High-Altitude Nutrition Hints
sort of diet is best for high-altitude climbing?*
A: Studies show that our bodies can process fats
and carbohydrates normally up to 5,000 meters, so any loss below
that elevation can be attributed to less than adequate intake.
Above 5,000 meters, however, weight loss seems to be unavoidable,
due to several factors: 1) loss of appetite and increased nausea
from the effects of altitude sickness; 2) change in overall metabolism;
and 3) the body's inability to digest food.*
The average-sized male climber can expect to burn upwards of 500-800
calories per hour at higher altitudes (the higher numbers are
for difficult carry days) so plan on consuming substantially more
than you eat back home. A good ratio seems to be 60-70% carbohydrates,
15-20% from fat and 15-20% from protein. Complex carbohydrates
provide the ongoing fuel needed to replenish glycogen stores,
while protein helps prevent excess deterioration of lean muscle
mass. Beware the very high-fat diet at altitude: reliance on foods
such as typical mountaineers' classics like Snickers bars, cheese,
jerky, nuts, and so forth can result in chronic muscular fatigue,
since a high-fat diet lacks the necessary level of readily-available
carbohydrates; furthermore, high-fat diets require more oxygen
during metabolism for processing, thus slowing down acclimatization.*
The simplest answer to this is: what
you'll eat, consistently, and a lot of it. Make sure you test-run
your food ahead of time on training climbs (eg. - on Rainier and
other similar training climbs that take you above 12,500') so
you learn what works best for you. By all means, take foods and
beverages you enjoy or you won't want to eat them. If you know
that your water treatment makes drinking unpleasant, take flavored
drink mixes like Tang, cocoa or Gatorade to help mask the taste
and add valuable carbohydrates. Also consider the weight of all
the food (especially if you're going to be carrying most of it
yourself!) -- dehydrated foods that are light weight but calorically
dense are highly desirable. Potato buds that you can mix with
dried turkey or other meat and hot water seems to be a concoction
that goes down pretty easily for most people at high altitude.
But if you absolutely hate the taste of any of your fare at sea
level, leave it behind.
* Resource: Burnik and others,
in Ch. 6, Some Anthropometric Changes on Extreme High Altitudes,
Science of Climbing and Mountaineering CD-ROM, available through
Human Kinetics. Research done on Everest, North Base Camp, 1997.