The major objective in training is to cause biologic adaptations in order to improve performance in a specific task. This requires adherence to carefully planned and executed activities. Attention is focused on factors such as frequency and length of workouts, type of training, speed, intensity, duration, and repetition of the activity. To enhance physiologic improvement effectively and to bring about a training change, a specific exercise overload must be applied. By exercising at a level above normal, a variety of training adaptations take place that cause the body to function more efficiently.
Aerobic System Adaptations to Exercise
- Increased ability to produce energy (ATP) by cellular mitochondria
- Increased intracellular aerobic system enzymes and mitochondria to produce ATP
- Skeletal muscle myoglobin content may increase up to 80% facilitating oxygenation
- Increased capacity of the muscle to mobilize and oxidize fat
- Greater capacity to oxidize carbohydrates and store carbohydrates as glycogen
- Hypertrophy of different muscle fibres depending on the type of training
Cardiovascular and Respiratory Changes
- Heart Size. The weight and volume of the heart increases with long term aerobic training due to enlargement of the left ventrical and thickening of its walls.
- Blood Volume. Plasma volume and total hemoglobin increase with endurance training thereby enhancing circulatory and thermoregulatory dynamics to facilitate oxygen delivery.
- Heart Rate. Resting and submaximal heart rate decreases. This is especially true for previously sedentary individuals.
- Stroke Volume. The hearts stroke volume increases significantly in endurance athletes as a result of increased heart volume and enhanced myocardial contractility.
- Cardiac Output. The heart’s increased outflow capacity with training is a direct result of improved stroke volume.
- Oxygen Extraction. Training produces significant increases in the amount of oxygen extracted from the blood stream. This is the result of more effective distribution of cardiac output to working muscles and of enhanced capacity of the trained muscle cells to extract and utilize oxygen.
- Blood Flow and Distribution. As the cell’s ability to deliver, extract, and utilize oxygen increases, less regional blood flow is required to meet the muscle’s oxygen needs.
- Blood Pressure. Regular aerobic training tends to reduce blood pressure during rest and submaximal exercise. The larges decreases occur in systolic pressure and are most apparent in hypertensive individuals.
- Respiratory Function. In submaximal exercise the trained individual ventilates less than prior to training reflecting increased efficiency.
As a general rule, aerobic capacity improves if exercise is of sufficient intensity to increase heat rate to about 70 % of maximum.
Exercise need not be strenuous in order to obtain positive results. An exercise heart rate of 70% maximum represents moderate exercise that can be continued for a long time with little or no discomfort. This training level is commonly referred to as “conversational exercise” in that it is sufficiently intense to stimulate a training effect yet not so strenuous that it limits a person from talking during the workout. It is unnecessary to exercise above this heart rate to improve physiologic capacity. To keep pace with the training effects, the work rate must be increased periodically to achieve the threshold heart rate or whatever target heart rate has been established. A person who began training by walking now has to walk more briskly; this is gradually replaced by jogging for periods of the workout and, eventually, continuous running required to achieve the same relative strenuousness at the desired target heart rate. If the progression in exercise intensity is not matched with training improvements, the exercise program essentially becomes a “maintenance” program for aerobic fitness.
What is a Calorie?
A calorie is a measure used to express the heat or energy value of food and physical activity. It is defined as the amount of heat necessary to raise the temperature of 1 litre of water 1 degree Celsius from 14.5 -15.5 degrees C. For example if 300 Calories is the caloric value of a particular food, then the energy trapped within the chemical bonds of this food, if released, would change the temperature of 300 litres of water by 1 degree C. Utilizing established medical research, we can calculate an estimate amount of calories burned from running.
What is a Body Mass Index?
The body mass index is calculated from a person’s height and weight, is a reliable indicator of “fatness” in sedentary individuals, and can be used to identify health risks. The BMI is the person’s weight divided by the square of the height:
It is meant to be used as a simple means of classifying sedentary individuals with an average body composition. For these individuals, the current value settings are as follows: a BMI of 18.5 to 25 may indicate optimal weight; a BMI lower than 18.5 suggests the person is underweight, while a number above 25 may indicate the person is overweight; a BMI below 15 may suggest the person has an eating disorder; a number above 30 indicates that the person is obese (over 40, morbidly obese). Accuracy of this measure is compromised by variable body composition, fitness level, muscle mass, bone mass, gender, etc.
For more information from the government and recommended guidelines for the public click here.
Remember that this information is not intended as a substitute for medical advice. If you are experiencing pain, consult your family physician or physiotherapist.