Chapter 6: Adaptations to Aerobic Endurance Training Programs

Acute Responses to Aerobic Exercise: Cardiovascular Responses Continued

•Blood pressure -Systolic blood pressure estimates the pressure exerted against the arterial walls as blood is forcefully ejected during ventricular contraction -Diastolic blood pressure is used to estimate the pressure exerted against the arterial walls when no blood is being forcefully ejected through the vessels, Control of local circulation -During aerobic exercise, blood flow to active muscles is considerably increased by the dilation of local arterioles -At the same time, blood flow to other organ systems is reduced by constriction of the arterioles

Key Terms: Cardiac Output and Stroke Volume

•Cardiac output(or Q): The amount of blood pumped by the heart in liters per minute (SV X HR) -From rest to steady-state aerobic exercise, cardiac output initially increases rapidly, then more gradually, and subsequently reaches a plateau -With maximal exercise, cardiac output may increase to four times the resting level(increased from 5 to 20 liters/min because of increased HR and SV) •Stroke volume: The quantity of blood ejected with each beat

Overtraining

•Cardiovascular responses -Greater volumes of training affect heart rate •Biochemical responses -High training volume results in increased levels of creatine kinase, indicating muscle damage -Muscle glycogen decreases with prolonged periods of overtraining •Endocrine responses -Overtraining may result in a decreased testosterone-to-cortisol ratio(more breakdown than buildup), decreased secretion of GH, and changes in catecholamine(ep and norep, dopamine) levels

Chronic Adaptations to Aerobic Exercise: Endocrine Adaptations

•Aerobic exercise leads to increases in hormonal circulation and changes at the receptor level •High-intensity aerobic endurance training augments the absolute secretion rates of many hormones in response to maximal exercise •Trained athletes have blunted responses to submaximal exercise

Acute Responses to Aerobic Exercise: Respiratory Responses

•Aerobic exercise provides for the greatest impact on both oxygen uptake and carbon dioxide production, as compared to other types of exercise •Significant increases in oxygen delivered to the tissue, carbon dioxide returned to the lungs, and minute ventilation provide for appropriate levels of alveolar gas concentrations during aerobic exercise

Overtraining: What are markers of aerobic overtraining?

Are we overtraining our aerobic athletes? •Decreased performance -Some of these will explicitly tell us, like this one although they are mostly well into being overtrained, but some are more difficult and subjective, or needed to be tested for in a lab, which takes time and costs money •Decreased percentage of body fat -Useful if accurately measured before •Decreased maximal oxygen uptake •Altered blood pressure •Increased muscle soreness •Decreased muscle glycogen •Altered resting heart rate •Increased submaximal exercise heart rate •Decreased lactate •Increased creatine kinase -We wouldn't really know, have to measure in a lab, but is an indicator of muscle damage, too much breakdown •Altered cortisol concentration •Decreased total testosterone concentration •Decreased ratio of total testosterone to cortisol •Decreased ratio of free testosterone to cortisol •Decreased ratio of total testosterone to sex hormone-binding globulin •Decreased sympathetic tone(decreased nocturnal and resting catecholamines) •Increased sympathetic stress response •Change in mood states -Look for mood changes as well, their willingness to train •Decreased performance in psychomotor speed tests

External and Individual Factors Influencing Adaptations to Aerobic Endurance Training: Altitude

•Changes begin to occur at elevations greater than 3,900 feet(1,200 m), it takes time to adapt, also leaves quickly when no longer needed, Like lots of this chapter, it is an exercise physiology review -Increased pulmonary ventilation(hyperventilation) -Increased cardiac output at rest and during submaximal exercise due to increases in heart rate -People may use hypo vs hyperbaric chambers, Oxygen masks, But should do the "live high, train low" approach for best benefits -Supplemental oxygen, it is all mental, they don't really need to change their oxygen saturation if at the same sea level, it may be beneficial if they are at altitude however, because it would then increase their oxygen saturation •Values being to return to normal within 2 weeks •Several chronic physiological and metabolic adjustments occur during prolonged altitude exposure, but go away once no longer needed

Detraining vs. Tapering

•Detraining -If inactivity, rather than proper recovery, follows exercise, an athlete loses training adaptations •Tapering -The planned reduction of volume in training that occurs before an athletic competition or a planned recovery microcycle, such as before a important competition, get them ready for it, but don't want to overtrain

Tidal Volume

•Figure 6.1 (next slide) -The slide shows the distribution of tidal volume in a healthy athlete at rest -The tidal volume compromises about 350 ml of room air that mixes with alveolar air, about 150 ml of air in the larger passages(anatomical dead space), and a small portion of air distributed to either poorly ventilated or incompletely filled alveoli(physiological dead space) Look at Diagram in Notes •Tidal volume(ml) which is One respiration(breath) at ~600 ml •Made up of -Anatomical dead space at ~150 ml -Physiological dead space at ~175 ml -Alveolar air at ~500 ml

Pressure Gradients

•Figure 6.2 (next slide) -Pressure gradients for gas transfer in the body at rest -The pressures of oxygen(PO2) and carbon dioxide(PCO2) in alveolar air, venous and arterial blood, and muscle tissue are shown Look at diagram in notes •From pulmonary artery: PO2 = 40, PCO2 = 46, low in oxygen •Lung, Capillaries, Alveoli: PO2 = 105, PCO2 = 40, O2 out, CO2 in because of pressure gradient(blood from pulmonary artery is low in oxygen and lung capillaries and alveoli are high in oxygen, so it diffuses out and CO2 in) •To pulmonary vein: PO2 = 100, PCO2 = 40, now high in oxygen •Left atrium and ventricle •Systemic arteries: PO2 = 100, PCO2 = 40 •Muscle, Capillaries, Muscle Fibers: O2 in, CO2 out because of pressure gradient, similar to above •Systemic veins: PO2 = 40, PCO2 = 46, now low in oxygen •Right atrium and ventricle, goes around again

Acute Responses to Aerobic Exercise: Respiratory Responses Continued

•Gas responses -During high-intensity aerobic exercise, the pressure gradients of oxygen and carbon dioxide cause the movement of gases across cell membranes -The diffusing capacity of oxygen and carbon dioxide increase dramatically with exercise, which facilitates their exchange

External and Individual Factors Influencing Adaptations to Aerobic Endurance Training: Hyperoxic Breathing, Smoking, Blood Doping, Genetic Potential

•Hyperoxic breathing -Breathing oxygen-enriched gas mixture during rest periods or following exercise may positively affect exercise performance -The procedure remains controversial as mentioned earlier •Smoking -Acute effects of tobacco smoking could impair exercise performance, Do not smoke •Blood doping -Can improve aerobic exercise performance and may enhance toleration to certain environmental conditions -Is unethical and poses serious health risks, very dangerous and even deadly -This is when people take out their blood and separate their red blood cells and put them back after some time to gain a higher concentration, they may even use other people which is even worse, This is different than platelet-rich plasma, which involves putting platelets at injured joints, most American insurance companies don't cover this because of risks as well, this is more with platelets and joint healing and nothing to do with red blood cells, just a similar process -They may also take erythropoietin(EPO), red blood cell stimulating hormone •Genetic potential -The upper limit of an individual's genetic potential dictates the absolute magnitude of the training adaptation

Chapter Objectives

•Identify and describe the acute responses of the cardiovascular and respiratory systems to aerobic exercise •Identify and describe the impact of chronic aerobic endurance training on the physiological characteristics of the cardiovascular, respiratory, nervous, muscular, bone and connective tissue, and endocrine systems •Recognize the interaction between designing aerobic endurance training programs and optimizing physiological responses of all body systems •Identify and describe external factors that influence adaptations to acute and chronic aerobic exercise, including altitude, sex, blood doping, and detraining •Recognize the causes, signs, symptoms, and effects of overtraining and detraining

Chronic Adaptions to Aerobic Exercise: Bone and Connective Tissue Adaptations

•In mature adults, the extent to which tendons, ligaments, and cartilage grow and become stronger is proportional to the intensity of the exercise stimulus, especially from weight-bearing activities

Key Point: Acute Aerobic Exercise Results In

•Increased cardiac output •Increased stroke volume •Increased heart rate •Increased oxygen uptake(and CO2 production) •Increased systolic blood pressure •Decreased diastolic blood pressure •Increased blood flow to active muscles

Brainstorm: Acute Responses to Aerobic Exercise

•Increased heart rate •Increased stroke volume •Increased cardiac output •Increased body temperature •Increased respiratory rate •Increased O2 extraction at the lungs •Increased CO2 production from the muscles •Increased vasodilation in working muscles, blood flow •Increased systolic blood pressure •Decreased or steady diastolic blood pressure -Why?, because of vasodilation, their is less pressure on the walls when the heart is relaxing/resting, diastolic blood pressure should never increase during exercise, if it does than it is probably a medical problem •Increased energy expenditure •Increased carbohydrate usage for fuel

Acute Responses to Aerobic Exercise: Cardiovascular Responses

•Stroke volume -End-diastolic volume is significantly increased -At onset of exercise, sympathetic stimulation increases stroke volume •Heart rate increases linearly with increases in intensity •Oxygen uptake -Increases during an acute bout of exercise -Is directly related to the mass of exercising muscle, metabolic efficiency, and exercise intensity

Brainstorm: Chronic Adaptations to Aerobic Exercise

•Increased stroke volume •Decreased heart rate -Because of increased stroke volume, cardiac output is still steady, but heart is working less, because it can push out more blood per beat •Decreased submaximal heart rate -With same intensity exercise, heart rate doesn't get as high as it did before the adaptation •Increase in left ventricle size •Better pulmonary diffusion •Increased respiratory rate •Increased tidal volume -More air can be inhaled per minute •Increased lactate threshold •Increased VO2 max -Better ability to use and consume oxygen, This and lactate threshold are markers of performance •Increased mitochondrial density •Increased capillary density •Increased red blood cell concentrations •Increased hematocrit concentrations •Increased plasma volume -This is one of the first adaptations to go away if they stop aerobic exercise, sweat is mostly water from blood plasma •Increased sweat rate -Onset of sweating is also earlier, so able to cool body quicker than others •Decrease in fat mass •Decrease in body fat percentage -As long as they have the same diet, nutrition, and stress levels they had before the adaptation •Better body composition control •Possibly? -BMR?, It may increase with sedentary, but not like it would with anaerobic exercise because of increased muscle mass -BP?, It may decrease, but this is not consistent with people and usually only for sedentary, they need to exercise every day to keep it low

Chronic Adaptations to Aerobic Exercise: Cardiovascular Adaptations

•Increases in maximal cardiac output, stroke volume, and fiber capillary density •Increased parasympathetic tone leads to decreases in resting and submaximal exercise heart rates

Key Point: During Aerobic Exericse

•Large amounts of oxygen diffuse from the capillaries into the tissues, increased levels of carbon dioxide move from the blood into the alveoli, and minute ventilation increases to maintain appropriate alveolar concentrations of these gases

External and Individual Factors Influencing Adaptations to Aerobic Endurance Training: Age and Sex

•Maximal aerobic power decreases with age in adults •Aerobic power values of women range from 73% to 85% of the values in men -Men, on average, have higher absolute VO2 maxes, and larger ventricles and lung capacity, due to bigger frame size •The general physiological response to training is similar in men and women

Key Terms: Maximal Oxygen Uptake and Resting Oxygen Uptake

•Maximal oxygen uptake: The greatest amount of oxygen that can be used at the cellular level for the entire body •Resting oxygen uptake: Estimated at 3.5 ml of oxygen per kilogram of body weight per minute(ml/kg/min), this value is defined as 1 metabolic equivalent(MET)

Acute Responses to Aerobic Exercise: Respiratory Responses - Blood Transport of Gases and Metabolic By-products

•Most oxygen in blood is carried by hemoglobin •Most carbon dioxide removal is from its combination with water and delivery to the lungs in the form of bicarbonate •During low- to moderate-intensity exercise, enough oxygen is available that lactic acid does not accumulate because the removal rate is greater than or equal to the production rate •The aerobic exercise level at which lactic acid (converted to blood lactate at this point) begins to show an increase is termed the onset of blood lactate accumulation, or OBLA

Chronic Adaptions to Aerobic Exercise: Muscular Adaptations

•One of the fundamental adaptive responses to aerobic endurance training is an increase in the aerobic capacity of the trained musculature •This adaptation allows the athlete to perform a given absolute intensity of exercise with greater ease after aerobic endurance training

Adaptations to Aerobic Endurance Training

•One of the most commonly measured adaptations to aerobic endurance training is an increase in maximal oxygen uptake associated with an increase in maximal cardiac output •The intensity of training is one of the most important factors in improving and maintaining aerobic power

Key Point: Overtraining

•Overtraining syndrome can lead to dramatic performance decreases in all athletes, the most common cause is high intensified training without adequate recovery

Key Point: Overtraining, Detraining, and Tapering

•Proper exercise variation, intensity, maintenance programs, and active recovery periods can adequately protect against serious detraining effects

Key Point: Aerobic Endurance Training Results In

•Reduced body fat •Increased maximal oxygen uptake •Increased running economy •Increased respiratory capacity •Lower blood lactate concentrations at submaximal exercise •Increased mitochondrial and capillary densities •Improved enzyme activity

Chronic Adaptions to Aerobic Exercise: Respiratory Adaptations and Neural Adaptions

•Respiratory adaptations -Ventilatory adaptations are highly specific to activities that involve the type of exercise used in training -Training adaptations include increased tidal volume and breathing frequency with maximal exercise •Neural adaptations -Efficiency is increased and fatigue of the contractile mechanisms is delayed

What would we do with an overweight client who wants to begin an exercise program?

•Should begin an aerobic training program -Walking is probably their best mode(type) at first, 5 days(frequency) of 30 minutes(time) at about a 4 - 5(intensity) -They may have to start with 15 - 20 minutes, can even break it up further into 10 minutes, at about 2 - 3 days a week in the first week, so they won't be too sore and quit, This is to get them to start forming habits of working out, getting them to enjoy it, we don't want to make it difficult their first week or they'll drop us right away, Our first goal is to not have them lose weight, they just need to start liking exercise at first •This program is different that what we would do •They may also swim if they have a lot of joint pain, but many do not like to or don't want to get in a bathing suit, They can also bike, which is non-weight bearing, or get on an Elliptical, we may have to show them what it is •We should include some resistance exercise too, this will increase their muscle tolerance of exercise and weight bearing -Most people have a cascading event cycle to why they don't workout, they may have done it in the past, but got hurt or starting feeling pain, so stopped working out, There are a lot of cases of something that led them down this path, we shouldn't just consider them as being lazy

Table 6.3: Adjustments to Altitude Hypoxia

•System, -Immediate adjustments, -Longer-term adjustments •Pulmonary -Hyperventilation -Increase in ventilation rate •Acid-base -Body fluid become more alkaline(pH > 7) due to reduction in CO2 with hyperventilation -Excretion of HCO3 - by the kidneys with concomitant reduction in alkaline reserve •Cardiovascular -Cardiac output increases at rest and during submaximal exercise, Submaximal heart rate increases, Stroke volume remaints the same or is slightly lowered, Maximal heart rate remains the same or is slightly lowered, Maximal cardiac output remains the same or is slightly lowered -Continued elevation in submaximal heart rate, Decreased stroke volume at rest and with submaximal and maximal exercise, Lowered maximal heart rate, Lowered maximal cardiac output •Hematologic -x -Increased red cell production(polycythemia), Increased viscosity, Increased hematocrit, Decreased plasma volume •Local tissue -x -Increased capillary density of skeletal muscle, Increased number of mitochondria, Increased use of free fatty acids, sparing muscle glycogen