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Monthly Health Review, April 2001
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Energy for sport
The aim of this issue is to discuss the materials necessary for providing
the content with energy for sporting activities. For a person to perform
to their maximum potential the combined effects of certain components
must be considered, these include: - genetics, lifestyle, state of health,
mental preparation, frequency and duration of training, type and quality
of training, rest and relaxation, and of course NUTRITION. Some factors
like genetics are out of our control (1).
Good nutrition is vital to good performance.
Carbohydrate and fat are the important fuels for any form of exercise
be it walking, cycling, washing the car, running, shelf-filling, or playing
squash. The amount used will depend on the type, intensity and duration
of the exercise. Protein is rarely used as fuel, except in extreme circumstances,
for example an arctic expedition, when the exercise is extremely strenuous
or prolonged, and food supply is limited (1).
Sport is a combination of 'anaerobic' and 'aerobic' exercise. 'Anaerobic'
exercise is not dependant on oxygen being present and generally refers
to activities requiring sudden bursts of energy when more carbohydrate
(in the form of glycogen) and less fat is being used, an example would
be weight lifting. 'Aerobic' relies on oxygen being available to the cells
and is used during slow, more rhythmic and sustained movement. This type
tends to use more fat, an example would be walking (1).
Duration of the exercise will affect the fuel mixture burned.
In the first 10 - 15 minutes of exercise, the main fuel used is normally
carbohydrate. After about 20 minutes the content will be using approximately
50/50 carbohydrate and fat. As the exercise continues, more fat and less
carbohydrate is used. Some carbohydrate will always be present because
fat cannot be burned without it (1).
The content stores carbohydrate as glycogen.
Glycogen is stored in small amounts in the muscles and liver. It is similar
in structure to starch and made up of lots of glucose units joined together.
During exercise, glycogen is broken first into glucose, then converted
into energy. This process happens only in muscles being used (1).
Fatigue occurs when muscle glycogen stores have run low.
When fatigue is experienced, the intensity of exercise should be reduced.
This enables muscles to use a greater proportion of fat and less glycogen.
Alternatively, the exercise should be stopped and muscle glycogen stores
allowed to recover (1).
Begin refuelling straight after training/exercise.
Glycogen manufacture is fastest in the two hours after exercise. Top-up
time depends on how hard the content has worked and the carbohydrate content
of food consumed after exercise. If glycogen stores in the content are low
and the carbohydrate value of food is low, re-fuelling will take longer
(1).
Regular training affects fuel mixture.
With regular training the content becomes better at using fat and sparing
glycogen. This means that the content is able to carry on exercising for
longer periods of time before Fatigue sets in. After all, we are 'training'
the content to cope with an increased amount of exercise (1).
A whole-food diet should provide a good foundation for training and
exercise.
A good quality diet should be low in caffeine, fizzy drinks, refined carbohydrates,
processed foods, simple sugars, artificial food colours and flavours.
Good amounts of water, fresh vegetables, fruits, wholegrains, complex
carbohydrates, fish and a moderate amount of meat should provide the necessary
energy-yielding nutrients (1). Physically active people would also benefit
from a wholefood diet because it will be richer in minerals and trace
elements than a diet high in processed and/or refined food (14).
Carbohydrates, fats and protein provide the content with fuel for producing
energy.
B vitamins, especially Thiamin (B1), Riboflavin (B2), Niacin (B3), pantothenic
acid (B5), and Biotin help the content use the fuel, as part of co-enzyme
systems. The B vitamins are involved in the work of every cell; some help
generate energy, while Pyridoxine (B6) helps the content to use Amino Acids
to make protein that can be used in many ways including making new tissue,
enzymes and hormones (1).
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Supplements in sport
A balanced multivitamin and mineral formulation may help guard
against deficiency and ensure that vital nutrients are not missing.
Many active or energetic people take extra B vitamins because
of their involvement in the release of energy from food. There is evidence
to suggest that the requirement for B vitamins increase with regular intensive
exercise (2).
CoQ10 is synthesised in the content or obtained from the diet. CoQ10
acts as a coenzyme in the process of energy production within the mitochondria
of cells and is essential for production of adenosine triphosphate (ATP),
the immediate energy currency of each cell. Studies show that 30-60mg
CoQ10 may improve exercise capacity when levels are deficient (4).
Siberian Ginseng (Eleutherococcus senticosus) is reported
to improve the content's ability to deal with Stress by helping the metabolism
of lactic and pyruvic acids released during the stress reaction. More
efficient production of energy has also been noted (5). Studies show that
Siberian Ginseng may help the content withstand strenuous physical exercise
and improve physical performance. Korean Ginseng (Panax ginseng)
may help reduce Fatigue during exercise by prolonging the time before
lactic acid accumulates (6).
Endurance athletes and women athletes may be at particular risk of Iron
deficiency through sweating losses, red-blood cell destruction and in
particular to increased iron demands by muscles during aerobic metabolism
(7). Deficiency of iron may also increase the risk of muscle Cramps as
a result of lactic acid build up (lactate Acidosis) (4). Low iron levels
will lead to reduced aerobic work capacity so that a person tires more
easily. Extra iron through the diet or food supplements may help to meet
these extra requirements by building up iron stores in the content.
During strenuous exercise, the content loses electrolyte minerals - Sodium,
Potassium, Chloride and Magnesium. Losses tend to be less in well-conditioned
bodies, for example trained athletes (7). Electrolyte sports drinks or
multimineral food supplements can be convenient ways to replenish
lost minerals, especially after strenuous exercise when sweating losses
are high.
Insufficient magnesium can affect muscle-building regimes. Deficiency
has been shown to halve muscle gains associated with specific training
(7). Magnesium levels are reduced in response to endurance/intense exercise
or strength training (8). Magnesium with B6 may be helpful in preventing
magnesium deficiency in those involved in strenuous exercise.
Studies on runners have shown that Chromium losses via urine increase
after exercise. Zinc levels can also be reduced via increased urinary
losses and through sweating; some highly trained athletes have a very
poor Zinc status (9). .
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Healthy bones and joints
The old adage "All things in moderation" holds true for sport and training,
when anything is carried out to extremes there is always retribution.
For example moderate exercise and adequate Calcium intakes protect against
bone loss, while extremes of exercise may be detrimental to bone health.
Some athletes and dancers in their twenties have recorded bone densities
as low as those of women in their seventies (7). The National Osteoporosis
Society recommends a daily Calcium intake of 1000mg/day for teenagers,
adult males and women 20 - 45 years.
Glucosamine Sulphate has been successfully used in helping the
recovery of a group of young athletes from cartilage injury (13). Intakes
were 1500mg daily for 40 days, then intake halved for a further 3 months.
Glucosamine Sulphate is an amino sugar that occurs naturally in the connective
tissue, cartilage, muscles, tendons, ligaments and also spinal discs and
heart valves. It stimulates cells involved in bone and cartilage production.
Recovery time from injury in football players was improved with 1800mg/day
Vitamin C and citrus Bioflavonoids for a minimum of one week (13).
Regular and intense exercise increases the requirement for a number of
vitamins and minerals, especially those involved in energy production
such as the B vitamins, Zinc and Iron and the antioxidant vitamins C and
E; and minerals Selenium, Zinc, Manganese and Copper.
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Antioxidants and exercise
Studies show that strenuous exercise may promote the production of free
radicals, which in excess can lead to cell and muscle tissue damage (2).
Increasing antioxidant intake may protect against potential tissue damage
and minor muscle injuries in active people (10). It has been shown that
athletes who supplement with 400mg/day of Vitamin E increase the
exercise period before lactic acid builds up in the muscle (11). A build
up of lactic acid in muscle tissue indicates incomplete metabolism of
glucose due to lack of oxygen in the muscle, which may arise when a small
amount of energy is converted from glucose without oxygen being present.
Vitamin C has been shown to be of use in reducing the incidence and symptoms
of upper respiratory tract Infections, commonly found in marathon and
other long distance runners, who are known to be vulnerable to respiratory
tract infections after races (12).
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From the homoeopathic medicine chest
It is prudent to keep a selection of homoeopathic remedies in the first-aid
box. An active person who takes part in regular sports activity would
be wise to keep the following in case of injury, sprains or strains:
- Aconite ~ for Shock and fear followed by . . .
- Arnica ~ useful for Bruised and sore muscles. ~ helpful after overuse
or injury.
- Bryonia ~ If there is Pain with the slightest movement.
- Hypericum ~ any injury that continues to be extremely sensitive.
- Rhus tox ~ useful for later stages. Pain is better once movement begins;
or if the limb stiffens if immobile.
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References:
- "Nutritional Guide to Sports and Fitness", Anita Bean B Sc. 1991.
- Am J Clin Nut 1993; 264: R992-8.
- Metab Brain Dis, Mar 1996. 11; 1:95-106.
- Food Science & Tech Today, 1989. 9;3:175-177.
- Siberian Ginseng: Current status as an adaptogen. In: "Economics
and Medicinal Plant Research" , vol. 1. N R Farnsworth et al. Academic
Press. 1985.
- "The Healing Power of Herbs", M. T. Murray. Prima. 1995.
- "Nutrition Concepts and Controversies", F. Sizer & E. Whitney.
West Publishing. 1994.
- J Am Coll Nutr. 1992. 11; 3: 326-329.
- "Sports Medicine". 1987; 4: 9-18.
- Int J of Sports Med, Nov 1995. 16; 8: 491-7.
- Med Sport Science. 1991; 32: 59-78.
- Am J Clin Nutr, 1993; 57:170-4.
- "Nutritional Influences on Illness", M. R. Werbach. Third Line
Press. 1996.
- Am J Clin Nutr, Aug 2000, 72:2 Supple, 585S-93S.
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