Part 3: Glucose feedings, electrolytes, and water uptake

Ingesting fluid before and during exercise minimizes the detrimental effects of dehydration on cardiovascular dynamics, temperature regulation, and exercise performance. Adding carbohydrate to an oral rehydration solution provides additional glucose energy for exercise. Adding electrolyes to the rehydration beverage maintains the thirst mechanism and reduces the risk of hyponatremia.

Concern centers on the dual observations that (1) a large fluid volume intake impairs carbohydrate uptake; while (2) a concentrated sugar solution impairs fluid replenishment.

Consuming 400-600 ml of fluid immediately before exercise, followed by regular fluid ingestion during exercise (250 ml every 15 mins) optimizes gastric emptying by maintaining relatively large volumes in the stomach.

Gastric emptying slows when ingested fluids contain a high concentration of particles in solution (osmolality) or possess high caloric content. Fewer particles facilitate water movement from the stomach for intestinal absorption. Too high osmolality you will get pulling of water into the intestine by osmosis and you will get stomach/bowel cramps. The ideal oral rehydration solution to maintain fluid balance during exercise and heat stress contains between 5-8% carbohydrates (divide the carbohydrate content in gram by fluid volume and multiply by 100). Adding a moderate amount of sodium to fluid stabilizes plasma sodium concentrations, which benefits the ultraendurance athlete at risk of hyponatremia. Added sodium in the rehydration beverage also reduces urine production and sustains the sodium-dependent osmotic drive to drink.

So next time you can check your rehydration drink be it 100 plus, Gatorade and see how they measure up to what I have just written :-).

Part 3: Carbohydrate replenishment after exercise

All carbohydrates and carbohydrate-containing foods do not digest and absorb at the same rate. There is something called the Glycemic Index which I have dwelt on in my book "Staying Healthy, Staying Vital."

A food with moderate-to high glycemic index rating offers more benefit for rapid replenishment of carbohydrate following prolonged exercise than one rated low, even if the replenishment meal contains a small amount of lipid and protein. The revised glycemic index however includes the glycemic load associated with the consumption of specified serving sizes of different foods (we won't dwell on this here).

Optimal glycogen replenishment benefits individuals in (1) regular training (2) tournament competition with qualifying rounds (3) events scheduled with only 1-2 days for recuperation. An intense bout of resistance (weight) training also significantly reduces glycogen resrves.

Recommendations:

Consuming carbohydrate-rich, high glycemic foods immediately following intense training or competiton speeds glycogen replacement. The optimal effectiveness of glycogenosis (restoring glycogen) is 30-60 minutes after exercise.

Part 3: Carbohydrate feedings during exercise

Physical and mental performance improves with carbohydrate supplementation during exercise. The addition of protein to the carbohydrate-containing beverage (4:1 ratio of carbohydrate to protein) may delay fatigue and reduce muscle damage.

When a person consumes carbohydrates during endurance exercise, the carbohydrate form exerts little negative effect on hormonal response, exercise metabolism, or endurance performance. The reason is straightforward: increased levels of sympathetic nervous system
hormones (catecholamines) in exercise inhibit insulin release. Concurrently, exercise increases a muscle's absorption of glucose, so any exogenous glucose moves into the cells with a lower insulin requirement.

Ingested carbohydrate provides a readily available energy nutrient for active muscles during prolonged intense [75% aerobic capacity] exercise [>1hour] and repetitive short bouts of near-maximal effort. Little benefit comes from carbohydrate feedings during low-intensity exercise [below 50% maximum] because fat oxidation fuels exercise with little demand on carbohydrate breakdown.

Soccer

Picture of me playing Soccer in Australia when I was younger. Leaner, meaner and able to do the 100m dash under 11 seconds then!

Part 3: Carbohydrate feedings prior to exercise

High intensity aerobic exercise for 1 hour decreases liver glycogen by about 55%, whereas a 2-hour strenuous workout almost depletes the glycogen of the liver and active muscle fibers.

Prior to exercise:

Confusion exists regarding the potential endurance benefits of preexercise ingestion of simple sugars. Some researchers argue that consuming rapidly absorbed high glycemic carbohydrates within 1 hour before exercising accelerates glycogen depletion. This negatively affects endurance performance by the following mechanism.

• A rapid rise in blood sugar triggers an overshoot in insulin release. An excess of insulin cause a relative hypoglcemia (called rebound hypoglycemia). Significant blood sugar reduction impairs central nervous system function during exercise.

• A large insulin release facilitates the influx of glucose into muscle, which disproportionately increases glycogen catabolism in exercise. At the same time, high insulin levels inhibit lipolysis, which reduces fatty acid mobilization from adipose tissue. Augmented carbohydrate breakdown and depressed fat mobilization contribute to premature glycogen and early fatigue.

Research in late 70s indicated that drinking a highly concentrated sugar solution before exercise precipitated early fatigue in endurance activities. However, subsequent research has not corroborated the negative effects of concentrated preexercise sugar feeds on endurance. This discrepancy in research findings has no clear explanations.

One way to eliminate any potential for negative effects of prexercise simple sugars is to ingest them at least 60 mins before exercising. This provides sufficient time to reestablish hormonal balance before exercise begins.

Part 3: Nutrition-Liquid & Prepackaged Bars, Powders, and Meals

Commercially prepared nutritional bars, powders, and liquid meals offer an alternative approach in precompetition feeding or as supplemental feedings during periods of competition.

Liquid Meals

Liquid meals provide high carbohydrate content but contain enough lipid and protein to contribute to satiety. They also supply the person with fluid because they exist in liquid form. The liquid meal digests rapidly, leaving essentially no residue in the intestinal tract. Liquid meals prove particularly effective during daylong swimming and tract meets, or during tennis, soccer, and basketball tournaments. in these situations, the person usually has little time for food.


Nutritional Bars
Also called "energy bars", "diet bars" or "protein bars", they contain a relatively high protein content that ranges from 10 to 90 g per bar. The often contain vitamins and minerals.

The typical 60g bar contains 25g of carbohydrate (100 kCal), 15g of protein (60kCal) and 5g o f lipid (45 kCal).

The composition of nutritional bars generally varies with their purpose. Energy bars contain a greater proportion of carbohydrates while "diet" bars are lower in carbohydrate content and higher in protein. "Meal replacement" bars have the largest energy content (240 to 900 KCal). However, they lack the broad array of plant fibers and phytochemicals found in food and contain a relatively high level of saturated fatty acids.

Nutritional Powders and Drinks

A high protein content between 10 and 50 g per serving represents a unique aspect of nutritional powders and drinks. They also contain added vitamins and minerals. The powders come in canisters or packets that readily mix with water., while the drinks come premixed in cans. They are often marketed as meal replacement energy booster or concentrated protein sources.

The composition of nutritional powders and drinks varies considerably from nutritional bars. For one thing, nutritional bars contain at least 15g of carbohydrates to provide texture and taste, whereas powders and drinks do not. This accounts for the higher protein content with nutritional powders and drinks.

Part 3:Precompetitive meal-Protein or Carbohydrate?

When I was in boarding school in Australia, we used to play competitive sports each Saturday morning. The usual breakfast is bacon and eggs, sometime sausages etc. Such foods ma satisfy the athlete, boarding master and parents. A meal of this type with is low carbohydrate content, actually thwarts optimal performance.

The following five reasons justify modifying or even abolishing the high-protein precompetition meal in favor of one high in carbohydrates:

1. Dietary carbohydrates replenish the significant depletion of liver and muscle glycogen from the overnight fast.
2. Carbohydrate digestion and absorption are more rapid than either protein or lipid. Thus, carbohydrate provides energy faster and reduces the feeling of fullness following a meal.
3. A high protein meal elevates resting metabolism more than a high carbohydrate meal because of protein's greater energy requirements for digestion, absorption and assimilation. This additional thermic effect could strain the body's heal-dissipating mechanisms and impair exercise performance in hot weather.
4. Protein catabolism for energy facilitates dehydration during exercise because the byproducts of amino acid breakdown require water for urinary excretion. About 50ml of water "accompanies" the excretion of each gram of urea.
5. Carbohydrate, not protein, serves as the main energy nutrient for short term anaerobic activity and high-intensity aerobic exercise.

The ideal precompetition meal maximizes muscle and liver glycogen storage and provides glucose for intestinal absorption during exercise. The meal should:

• Contain 150 to 300 g og carbohydrate
• Be consumed 3-5 hours before exercising
• Contain relatively little fat and fiber to facilitate gastric emptying and minimize gastrointestinal distress.

Part 3: Nutrition-Precompetitive meal

Athletes often compete in the morning following an overnight fast. Significant depletion occurs in the body's carbohydrate reserves over an 8-12 hour period without eating. This occurs even if the person previously follows appropriate dietary recommendations. The precompetition meal is to provide adequate carbohydrate energy and ensures optimal hydration. Fasting before competition or training makes no sense physiologically because it rapidly depletes liver nad muscle glycogen and impairs exercise performance (but should not overdo it either as to high carbohydrate load can lead to abdominal cramps due to osmosis.ie water pulled into intestine due to high osmolality).

If a person trains or competes in the afternoon, breakfast becomes the important meal to optimize glycogen reserves. For late afternoon training (my usual timing) or competition, lunch becomes the important source for topping glycogen stores.

Asa general rule, competition day should exclude foods high in lipid and protein. Such foods digest slowly and remain in the digestive tract longer than foods containing similar energy as carbohydrate. Note that is takes 3-4 hours to digest and store a carbohydrate rich precompetition meal as muscle and liver glycogen.

Part 3: Eat More, Weigh less

Physically active individuals generally consume more calories per kg of body mass than sedentary counterparts. The extra energy required for exercise accounts for the larger caloric intake. Paradoxically, the most active men and women, who eat more on a daily basis, weigh less than those who exercise at a lower total caloric expenditure.

Thus, regular exercise allows a person to "eat more yet weigh less" while maintaining a lower percentage of body fat , despite the age-related tendency toward weight gain. Physically active persons maintain a lighter and leaner body and a healthier heart disease risk profile, despite intake of the typical Malaysian diet.

Part 3: Optimal Nutrition For Exercise

An optimal diet supplies nutrients in adequate amounts for tissue maintenance, repair, and growth without excess energy intake. Dietary intake for active people must account for energy demands of the particular chosen sport and its training demands. The physically active person person must obtain sufficient energy and macronutrients to replenish liver and muscle glycogen, provide amino acid building blocks for tissue growth and repair, and maintain a desirable body weight. Lipid intake must also provide essential fatty acids and fat-soluble vitamins.

The large number of teenagers and adults, including competitive athletes, who exercise regularly to keep fit do not require additional nutrients beyond those obtained through the regular intake of a nutritionally well-balanced diet.

Part 2: Water: Output

Water loss from the body occurs in 4 ways:

1.Urine:

The kidney is obligated to rid metabolic byproducts such as urea, an end product of protein metab olism. Large quantity of protein used for energy accelerates dehydration during exercise.

2.Skin:

Each day a person under normal temperature lose 500 to 700 ml of sweat. During prolonged exercise an athlete can lose up to 12L of sweat in hot conditions (at the rate of 1L per hour).

3.Vapor:

Water loss via small droplets in exhaled air accounts for 200-300ml per day.

4.Faeces:

Water loss in faces is around 100-200ml daily.

Hyponatremia

There is need to drink before, during and after exercise. In many circumstances people are recommended to drink plain, hypotonic water. However, excessive fluid intake can produce hyponatremia or water intoxication. A sustained low plasma sodium concentration creates an osmotic imbalance across the blood-brain barrier that causes rapid water influx to the brain. This can result in confusion, malaise, headache, cramping, seizures etc.

To reduce overhydration and hyponatremia risk in prolonged exercise you can do the following:

1. Drink 400-600 ml of fluid 2 to 3 hours before exercise.
2. Drink 150 to 300 ml about 30 minutes before exercise.
3. Drink no more than 1L per hour of plain water spread over 15 minutes interval during or after exercise.
4. Add a small amount of sodium to the ingested liquid.

This information is more for endurance athletes.

Part 2: Water: Input

A sedentary adult needs about 2.5 L of water a day. This varies depending if the person is active or those living in hot and humid conditions.

Sources of water:

1. Foods - Fruits and vegetables contain a lot of water.

2. Liquids - an average individual normally consumes 1200ml of water. Exercise and thermal stress increase the need for fluid by five to six times this amount.

3. Metabolic water - the breakdown of macronutrient (fat, carbohydrates, and protein) molecules in energy metabolism forms water and carbon dioxide.

Part 2: Water: Oxygen water

These days you can see athletes endorsing oxygenated water. National shuttler Lee Chong Wei is one of them. There is very little oxygen in water in the first place and even if it is seven or ten times the oxygen content of normal water as has been claimed, this is negligible. Humans breathe in oxygen via the lungs, not via the gastrointestinal tract, for we do not have gills like fish. Oxygen is unlikely to bind with water, and even if it did, how can it reach the cells if taken via the gastrointestinal tract. Why didn’t the person who invented the technology of binding oxygen to water win any scientific awards if there was such a technology? And if the oxygen is compressed into the bottle, surely it will dissipate when you open the cap.

Moreover, super-oxygen water usually costs three times the price of normal bottled water. We humans were not designed to absorb oxygen via the stomach. That’s basic science. Some things that Mother Nature created can’t be changed. If anything is free, it is oxygen. Just take a few deeper breaths and there you instantly have more oxygen in your blood than drinking a bottle of super-oxygenated water.

It is the red blood cells that deliver oxygen to the cells and organs. Oxygen deprivation to the cells is due to many reasons such as atherosclerosis or lead poisoning whereby the red blood cells cannot bind oxygen well.

So please don't buy the expensive water as it won't enhance your exercise performance.

Part 2: Water

Water makes up about 40-70% of the body mass, depending on age, gender and body composition. Body fat has a low water content (10% of weight), while 60% of the weight of muscle is water.

Water serves as the body's transport and reactive medium; diffusion of gases always takes place across surfaces moistened by water. Nutrients and gases travel through the water in urine and faeces.

Water in conjunction with various proteins, lubricates joints and cushions a variety of moving organs such as heart, lungs, intestines, and eyes. Because water is noncompressible, it gives structure and form to the body through the turgor it provides for body tissues.

Water has tremendous heat-stabilizing qualities because it can absorb a lot of heat with only small changes in temperature. This quality, combined with water's high heat of vaporization, maintains a relatively stable body temperature during (1) environmental heat stress (2) the increased heat load generated during exercise.

Part 2: Minerals and Exercise Performance

Consuming mineral supplements above recommended levels on a long or-short term basis does not benefit exercise performance or enhance training responsiveness.

Mineral Loss in Sweat

Excessive water and electrolyte loss impairs heat tolerance and exercise performance. It also leads to severe dysfunction culminating in heat cramps, heat exhaustion/stroke. During an event a male athlete may lose up to 5kg of water from sweating. This corresponds to 8g of salt depletion, because 1kg of sweat contains 1.5 g of salt.

Trace Mineral & Exercise

Strenuous exercise may increase excretion of chromium, copper, zinc and manganese.

There are many supplements athletes may take but for most athletes, trace mineral deficiency does not compromise exercise performance or overall health.

Battle Plan For Cardiovascular Disease

Dear All,

This is my latest published book. Finished it a year ago but only now did the publisher printed it. I have at least 4 other books I finished but not published.