 |  Perspectives in Nutrition, 5/e Gordon M. Wardlaw,
Ohio State University
Margaret W. Kessel,
Ohio State University
Sports Nutrition
Chapter 14 Summary- A gradual increase in regular physical activity is recommended for all healthy
persons. A minimum plan includes at least a total of 30 minutes of physical
activity per day. A more intense program should begin with warm-up exercises,
to increase blood flow and warm the muscles, and end with cooldown exercises.
Regular resistance activities and stretching add further benefits.
- Human metabolic pathways extract chemical energy from food and transforms
it into ATP, the compound that provides energy for body functions.
- In glycolysis, glucose is broken down (oxidized) into pyruvate, a three-carbon
compound, yielding some ATP. The pyruvate is metabolized further via the aerobic
pathway to form carbon dioxide (CO2) and water (H2O) or via the anaerobic pathway
to form lactate.
- At rest, muscle cells mainly use fat for fuel. For intense exercise of short
duration, muscles mostly use phosphocreatine (PCr) for energy. During more sustained
intense activity, muscle glycogen breaks down to lactate. For endurance exercise,
both fat and carbohydrate are used as fuels; carbohydrate is used increasingly
as activity intensifies. Little protein is used to fuel muscles.
- VO2 max is a measure of the maximum volume of oxygen one can consume per unit
of time. Oxygen consumption is measured by exercising the subject at an increasing
pace and workload until fatigue occurs. The amount of oxygen consumed right
before total exhaustion is VO2 max. The value of VO2 max varies among individuals
but usually improves with exercise training.
- Anyone who exercises regularly should consume a diet that meets energy needs
and is moderate to high in carbohydrates and fluid.
- Athletes should consume enough fluid to both minimize loss of body weight
and ultimately restore preexercise weight. Sports drinks aid fluid, electrolyte,
and carbohydrate replacement. Their use especially should be considered when
continuous activity lasts beyond 60 minutes.
- High-glycemic-index carbohydrates should be consumed by an athlete within
2 hours after a workout to begin restoration of muscle glycogen stores. Some
protein in the meal is also helpful. The use of low-glycemic-index carbohydrates
in the pre-event meal may help some endurance athletes.
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2002 McGraw-Hill Higher Education