5. Define respiratory exchange ratio and crossover concept (in your response include the importance of these terms to an exercise physiologist). Sketch a graph showing, the crossover concept and explain how chronic endurance training can affect the shape of the curves.
1. Describe the steps of muscle contraction from nerve impulse to gross movement. Include the cross-bridge cycle and role of ATP in the process.
2. Utilize the Fick equation to explain how heart rate, stroke volume, and arterial-venous oxygen difference (A-V02 D) change to increase V02 in the following situations. Be sure to also explain the mechanisms behind these changes: ‘ a. Short term: As exercise intensity increases during a single bout of exercise b. Long term: VO2max changes with chronic endurance training.
Seleet an external stressor (heat, cold, or altitude) and describe how the body acclimates (adapts) to it.
4. Identify two physical adaptations to resistance training and explain the mechanisms behind these adaptations.
Respiratory exchange ratio (RER) is the ratio of the volume of carbon dioxide (CO2) produced to the volume of oxygen (O2) consumed during metabolism. It is an important measure of energy metabolism during exercise and can be used to determine which fuel source the body is primarily using, carbohydrates or fats. The crossover concept refers to the point during exercise where the body shifts from primarily using fats as fuel to primarily using carbohydrates as fuel. The importance of RER and the crossover concept to an exercise physiologist lies in their ability to provide insight into an individual’s metabolic state during exercise, which can be used to develop more effective training programs.
Chronic endurance training can affect the shape of the curves by shifting the crossover point to the right, indicating that the body is better able to utilize fats as a fuel source during exercise. This occurs due to increased mitochondrial density and oxidative enzyme activity, which allows for more efficient fat oxidation. As a result, the body is able to spare glycogen stores and delay the onset of fatigue.
a. As exercise intensity increases during a single bout of exercise, heart rate, stroke volume, and arterial-venous oxygen difference (A-V02 D) all increase to increase VO2. Heart rate increases due to sympathetic nervous system activation, stroke volume increases due to increased venous return and subsequent stretch of the ventricles, and A-V02 D increases due to increased oxygen extraction by the muscles.
b. With chronic endurance training, VO2max increases due to various adaptations including increased mitochondrial density and oxidative enzyme activity, increased capillary density, and increased stroke volume at maximal exercise. These adaptations allow for more efficient oxygen delivery and utilization by the muscles, leading to a higher VO2max.
Heat acclimation is the process by which the body adapts to heat stress. This involves increased sweat production, earlier onset of sweat, and increased plasma volume to help dissipate heat more efficiently. Additionally, heat acclimation leads to a lower core body temperature during exercise and an increased tolerance to exercising in hot environments.
Two physical adaptations to resistance training are increased muscle hypertrophy and increased strength. Muscle hypertrophy occurs due to an increase in muscle protein synthesis, which leads to an increase in the size of individual muscle fibers. Increased strength occurs due to neural adaptations such as increased recruitment of motor units and improved synchronization of motor unit firing, as well as structural adaptations such as increased muscle fiber size and improved muscle-tendon junctions.