Chapter 13BIOL 1400Dr. Mohamad H. Termos Nutrition: Fitness and Sports
Benefits of regular physical activity - Improvement of heart function - Less injury - Better sleep habits - Body composition improvement - Stress reduction - Positively affects blood pressure, blood cholesterol, and blood glucose regulation - Aids in weight control
Energy need • Your body runs on water, oxygen, and food (primarily carbohydrate and fat). • The chemical reactions that use these substances to make energy are called metabolism
Glucose need • Glucose comes from carbohydrate-rich foods • During exercise, the body supplies glucose to the muscles from the stores of glycogen in the liver and in the muscles themselves • Diet affects glycogen storage and use
Glucose Use • Intensity of activity affects glycogen use: intense activities deplete glycogen very quickly • Lactic acid: produced during very high intensity workouts • Duration of activity affects glycogen use: - during the first 20 minutes of a moderate workout, a person use mostly glycogen for fuel - as muscle glycogen becomes depleted, the liver begins to break down its glycogen reserves Glucose during activity: • Obtained from muscle and liver glycogen stores; glucose from food and beverages
Fat Use during Exercise • When you exercise, the fat your muscles burn comes from the fatty deposits in all over the body • A person who is of desirable body weight may store 25 to 30 pounds of body fat but only about 1 pound of carbohydrate • Although your supply of fat is almost unlimited, the ability of your muscles to use fat for energy is not.
Fat Use Duration of activity affects fat use: • The longer the duration, the more free fatty acids that are used Intensity of activity affects fat use: - High intensity activities use less free fatty acids as a fuel source Training affects fat use: - Body is able to adapt and use fatty acids more as a fuel source can help spare glycogen
Fat Use For most people, fat is not used much as a fuel for exercise until you work out aerobically for at least 20 minutes, and is not used as a primary fuel until after 2 hours The more moderate the intensity of activity and the longer the duration, the greater the use of fat for fuel. The higher the intensity of activity, the greater the use of glucose for fuel.
Protein Use Protein used in muscle building • Protein synthesis is suppressed during activities. • In the hour post-workout, protein synthesis accelerates beyond normal resting levels. • Eating carbohydrate together with protein after the workout, enhances muscle protein synthesis
Protein Use Intensity and duration of activity affect protein use during activity • Long duration workout that deplete glycogen stores body becomes more dependent on protein as a fuel source • Anaerobic activities (weight lifting) does not use much protein for fuel, but does demand more protein to build muscle Training affects protein use • The higher the degree of training, the less protein a person uses during an activity • Protein intake during post-workout is still important
Vitamins and Exercise • Vitamins are the links and regulators of energy-producing and muscle-building pathways. • Without them, your muscles’ ability to convert food energy to body energy is hindered and muscle protein formation is slowed. • The B vitamins are of special interest to athletes and exercisers because they govern the energy-producing reactions of metabolism
Minerals and Exercise • Iron is a core component of the body’s oxygen taxi service: hemoglobin and myoglobin. • A lack of oxygen compromises the muscle’s ability to perform
Fluid Needs and Exercise • Replenishing fluid lost during exercise is easily accomplished by drinking fluid before, during, and after exercise • Ignoring body fluid needs can hinder performance and increase risk of heat-related injury • Heat stroke: an acute and dangerous reaction to heat buildup in the body, requiring emergency medical attention: also called sun stroke
Fluids and Electrolytes • Hyponatremia: - low sodium levels in blood - caused by exercise sweating or over-consumption of water (diluting body’s fluids) - can cause muscle cramping
Fluid Replacement Drinks • Sports drinks are designed to enhance the body’s use of carbohydrate and water • The carbohydrate in a sports beverage serves three purposes during exercise: - Becomes an energy source for working muscles. - Helps maintain blood glucose at an optimum level - Helps increase the rate of water absorption from the small intestine, helping maintain plasma volume.
Food for Fitness • The best nutrition prescription for peak performance is a well-balanced diet • Two critical nutrition periods for the athlete are the training diet and the pre-competition diet. • An eating plan that supplies 60% of calories from complex carbohydrate, 15% of calories from protein, and 25% of calories from fat will enable both athletes and fitness enthusiasts to supply muscles with a proper fuel mix and maintain health.
Facts about protein supplements • Protein and amino acids do not go directly to build muscle, and in fact, can increase body fat composition when consumed in excess of what the body requires • Continuous protein supplementation (in excess) can cause rapid, irreversible liver and kidney damage.