Ex Phys. Ch.13

How large of a role does genetics play in determining a person's VO2max?

-50% of the VO2 max of an untrained subject can be explained by genetic differences between individuals. -Some individuals can be ''low responders'' or ''high responders'' to exercise training. Low responders achieve only 2% to 3% improvement in VO2 max. High responders achieve a 50% improvement in VO2 max. These different variations in the training response illustrate the fact that heritability of the training adaptation is great and approached 47%

List the important secondary signaling pathways in skeletal muscle and indicate the adaptive effect they signal.

-AMPK: this molecule regulates numerous energy-producing pathways in muscle by stimulating glucose uptake and fatty acid oxidation during exercise. -P38: once activated it can contribute to mitochondrial biogenesis by activating PGC-1a. -PGC-1a: regulates many other endurance exercise-mediated changes in skeletal muscle; the formation of new capillaries, a fast-to-slow muscle fiber type shift, and synthesis of antioxidant enzymes. Also increased the muscle's ability to metabolize fat and to take up glucose into the muscle fiber. -Calmodulin-Dependent Kinase (CaMK): exerts influence on exercise-induced muscle adaptation by contributing to the activation of PGC-1a -Calciuneurin: participates in several adaptive responses in muscle which include: fiber growth/regeneration and the fast-to-slow fiber type transition that occurs as a result of endurance exercise training. -NFkB: promotes the expression of several antioxidant enzymes that protect muscle fibers against free radical-mediated injury. -mTOR: promotes increased translation that results in increased protein synthesis. -All these signaling molecules are activated by one of the four primary signaling pathways, and act directly or indirectly to increase gene expression of specific muscle proteins.

Define preload, afterload, and contractility, and explain the role of each in the maximal stroke volume that occurs with endurance training.

-An increase in Preload (EDV) results in stretch of the left ventricle and a corresponding increase in cardiac contractility. Both plasma volume, venous return, and ventricular volume all increase. -Afterload (TPR) refers to the peripheral resistance against which the ventricle is contracting as it tries to push blood into the aorta. Afterload decreases, and there is a decrease in arterial constriction. However there is an increase in the maximal muscle blood flow with no change in mean arterial pressure. -Contractility (which increases); is the intrinsic strength of the cardiac muscle independent of preload, but a change in preload will affect the force of contraction.

Describe the typical change in VO2max with endurance training programs and the impact of a person's initial VO2max value on the magnitude of the expected increase in VO2max

-Average is 15 to 20% increase -Small increases in individuals with high initial, VO2 max; individuals with high initial VO2 max may require higher exercise training intensities (> 70% VO2 max) to obtain improvements. -Genetics account for about 50% of VO2 max; such as high and low responders to training related to genetics.

Discuss how training increases VO2max and the time course for changes in stroke volume, cardiac output, and a-vO2diff.

-Following short-duration training, all of the training-induced improvements in VO2 max is due to increases in maximal cardiac output. During long-duration of training increases in VO2 max is due to increases in both maximal cardiac output and the maximal a-vO2 difference. -For untrained individuals this change can happen within 1 to 4 months with endurance training. In this short time span VO2 max, cardiac output, and stroke volume increase. -It takes a longer training period, of about 32 months or more, for there to show a documented increase in VO2 difference.

Explain how "high intensity" endurance training improves acid-base balance during exercise.

-Increased in mitochondrial number; less carbohydrate utilization = less pyruvate formed. -Increased NADH shuttles; less NADH available for lactic acid formation. -Change in LDH formation; heat form (H4) has lower affinity for pyruvate = less lactic acid formation.

List the 4 primary signal transduction pathways in skeletal muscle.

-Muscle stretch -Increases in cellular free calcium -Elevated free radicals -Decreases in muscle phosphate/energy levels

Describe the basic principles of training: overload, progression, reversibility, specificity.

-Overload principle states that an organ system or tissue must be exercised at a level beyond what it is usually accustomed to in order to achieve a training adaptation. -Reversibility principle states that the fitness gains achieved by exercising at an overload is quickly lost when the training is stopped and the overload is removed. -Specificity principle states that exercise training is specific to the muscles involved in that activity, the fiber types recruited, the principle energy system involved (such as anaerobic vs aerobic), the velocity of contraction, and the type of muscle contraction (concentric, eccentric, isometric). -Progression principle states that once an adaptation to an overload stimulus has occurred, the physiological system must be overloaded again for further adaptation to occur.

Describe the effects of anaerobic training on the biochemical properties of skeletal muscle fibers.

-Sprint training and high-intensity interval training improve muscle buffer capacity. The mechanisms responsible for these improvements in the muscle buffering capacity are: increased levels of both intracellular buffers and hydrogen ion transporters. High intensity exercises result in an accelerated production of lactate and hydrogen ions. -Sprint training in untrained individuals results in hypertrophy of fast type IIa and IIx muscle fibers along with elevated activities of enzymes involved in the ATP-PC system. An increase in fiber size is associated with a rise in muscle strength. Because the activity of enzymes involved in the ATP-PC system is improved, it results in an improved ability to rapidly breakdown phosphocreatine for energy during high-intensity exercise.

List and describe the primary changes that occur in skeletal muscle as a result of endurance training.

-There is a fast-to-slow shift in muscle fiber type: There is a reduction in fast fibers and an increase in number of slow fibers, magnitude of fiber type change is determined by duration of training, type of training, and genetics. -There is an increased number of capillaries surrounding muscle fibers: enhanced diffusion of oxygen, and an improved removal of wastes. -Increased volume of both mitochondrial subpopulations in the active skeletal muscle fibers as a result of endurance training and high-intensity interval training.

Explain why VO2max declines when endurance exercise is discontinued.

Because both maximal cardiac output and oxygen extraction decline over time with detraining.

Identify 6 training variables

Frequency, intensity, duration (time), type of exercise (endurance, explosive, etc), volume, type of contraction (eccentric, concentric, isometric)

According to the VoPP, what might you expect for a VO2max for a healthy, sedentary, college aged student?

Healthy sedentary college aged student: males: 45, females: 38