Adaptations t A to Aerobic bi Endurance E d Training Programs
Ann Swank, PhD, CSCS, FACSM
Exam Thursday • • • • •
Chapters 1, 2, 5, 6 p Choice Multiple True/False Fill-in-the-blank Short Answer
Key Terms .
• cardiac output (or Q): The amount of blood pumped by the heart in liters per minute (SV × HR). • stroke volume: The quantity of blood ejected with ith each hb beat. t
Key Term • 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 off oxygen per kilogram kil off b body d weight i ht per minute (ml · kg–1 · min–1); this value is defined as 1 metabolic equivalent (MET) (MET).
Acute Responses to Aerobic Exercise • Cardiovascular Responses – Stroke Volume • Increases I with ith th the onsett off exercise i via i SNS • End-diastolic volume is significantly increased
– Oxygen yg Uptake p • increases during an acute bout of aerobic exercise • is directly related to: – the mass of exercising muscle – metabolic efficiency – exercise intensity
Acute Responses to Aerobic Exercise • Cardiovascular C di l Responses R – Cardiac Output • From rest to steady-state aerobic exercise exercise, cardiac output – initially increases rapidly – gradually reaches a plateau • With maximal exercise, cardiac output may increase to four f times the resting level
– Heart Rate • Heart rate increases linearly with increases in intensity
Acute Responses to Aerobic Exercise • Cardiovascular Responses – 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. • Systolic significantly increases with aerobic exercise
Blood Pressures in the Circulatory System • Figure 6.1—Blood pressures in the various portions of the circulatory system
Acute Responses to Aerobic Exercise • Cardiovascular Responses – Control of Local Circulation • dilation of local arterioles leads to increased blood flow to active muscles • blood flow to other organ g systems y is reduced by y constriction of the arterioles
Respiratory Definitions • Tidal Volume is the amount of air breathed in during the normal inspiration & expiration • Respiratory Rate is the number of breaths taken every minute • Minute Ventilation – Amount of air breathed during one minute – Product of Tidal Volume and Respiratory Rate
Acute Responses to Aerobic Exercise • Respiratory Responses – provides for a large impact on: • oxygen uptake • carbon dioxide production
Tidal Volume • Distribution of tidal volume in a healthy athlete at rest – ~350 ml of room air that mixes with alveolar air – ~150 ml of air in the larger passages (anatomical dead space) – small portion of air distributed to either poorly ventilated or incompletely filled alveoli (physiological dead space)
Key Point • During aerobic exercise: – large amounts of oxygen diffuse from the capillaries into the tissues – increased levels of carbon dioxide move from the blood into the alveoli – minute ventilation increases to maintain appropriate alveolar concentrations of these gases
Acute Responses to Aerobic Exercise • Respiratory Responses – pressure gradients of oxygen and carbon dioxide cause the movement of gases across cell membranes – diffusing capacities of oxygen and carbon dioxide increase dramatically with exercise • partial pressure differences are greater as exercise i t intensity it increases i • may facilitate gas exchange
Pressure Gradients • Pressure gradients for gas transfer in the body at rest
Acute Responses to Aerobic Exercise • Respiratory Responses – Blood Transport of Gases and Metabolic By-Products • Most O2 is carried by hemoglobin • Most CO2 removal is from its combination with H2O and delivery y to the lungs g in the form of HCO3
– During low- to moderate-intensity exercise • enough O2 is available that La does not accumulate • removall rate t is i > the th production d ti rate t • aerobic exercise level at which blood La begins to show an increase is OBLA
Chronic Adaptations p to Aerobic Exercise • • • • • •
Cardiovascular Adaptations p y Adaptations p Respiratory Neural Adaptations p Muscular Adaptations Bone and Connective Tissue Adaptations Endocrine Adaptations
Table 6.1 61
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T bl 6.1 Table 6 1 (continued) ( ti d)
Chronic Adaptations to Aerobic Exercise Exercise—Cardiovascular Cardiovascular Adaptations • M Mustt consider id training t i i principles i i l to t achieve hi changes • Changes include: – – – – – – –
> SVmax > SVrestt > a-vO2diff > capillary p y density y < HRrest No change in HRmax > Cardiac Output
Chronic Adaptations to Aerobic Exercise—Respiratory Adaptations • Increased tidal volume p • Increased respirations • Increased minute ventilation
Chronic Adaptations to Aerobic Exercise—Neuromuscular Adaptations • Mechanical M h i l efficiency ffi i is i improved i d – Decreased loss of energy to wasted movement
• IIncrease in i the th aerobic bi capacity it off trained t i d musculature – More capillaries locally – More glycogen stored – More mitochondria
Chronic Adaptations p to Aerobic Exercise • Bone and Connective Tissue Adaptations – Improvements are proportional to the intensity of the exercise stimulus – Especially from weight-bearing activities
• Endocrine Adaptations – Increases in hormonal circulation and changes at the receptor level – Augmented g secretion rates of many y hormones in response p to maximal exercise – Trained athletes have blunted responses to submaximal exercise
Designing g g Aerobic Endurance Programs for Optimizing Adaptations
Key Points • One of the most commonly measured adaptations to aerobic endurance training is an increase in maximal oxygen uptake (VO2max) associated with an increase in maximal cardiac output output. • The intensity of training is one of the most important factors in improving and main maintaining aerobic power.
Key Point • Aerobic endurance training results in reduced body fat, increased VO2max, increased respiratory capacity, increased point of OBLA, increased mitochondrial and capillary densities densities, and improved enzyme activity.
Physiological y g Variables in Aerobic Endurance Training • Table 6.2 (next slides) – These subjects completed a short-term (three- to six-month) aerobic endurance training program. – BTPS = body temperature and pressure, saturated
Table 6.2 62
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Table 6.2 6 2 (continued)
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Table 6.2 6 2 (continued)
External Influences on the Cardiorespiratory Response
External Influences on the Cardiorespiratory Response • Altitude – Changes begin to occur at elevations greater than 3 900 feet (1 3,900 (1,200 200 m): • Increased pulmonary ventilation • Increased cardiac output at rest and during submaximal exercise due to increases in heart rate
– Values begin to return toward normal within 2 weeks – Several chronic adjustments occur during prolonged altitude exposure
Table 6.3 63 BAD
GOOD
External Influences on the Cardiorespiratory Response •
H Hyperoxic i B Breathing thi – Breathing oxygen-enriched gas mixtures during rest periods or following exercise may positively affect exercise performance – Procedure remains controversial controversial.
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Smoking – Acute effects of tobacco smoking could impair exercise performance – Chronic Ch i effects ff t WILL
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Blood Doping – Artificially increasing red blood cell mass is unethical and poses serious i h health lth risks i k – Can improve aerobic exercise performance – May enhance tolerance to certain environmental conditions
Individual Factors Influencing Adaptations to Aerobic Endurance Training • Genetic Potential g and Sex • Age • Overtraining – Cardiovascular Responses – Biochemical Responses – Endocrine Responses
• Detraining
Individual d dua Factors acto s Influencing ue c g Adaptations daptat o s to Aerobic Endurance Training • Genetic Potential – Upper limit of an individual’s genetic potential dictates the absolute magnitude of the training adaptation
• Age g and Sex – Maximal aerobic power decreases with age in adults – Aerobic power of women is 73% to 85% of men’s – Physiological Ph i l i l response tto ttraining i i iis similar i il iin men and women
Key Point • Overtraining can lead to dramatic performance decreases in athletes of all training levels and is caused by mistakes in the design of the training program.
Individual d dua Factors acto s Influencing ue c g Adaptations daptat o s to Aerobic Endurance Training • What Are the Markers of Aerobic Overtraining? – – – – – – –
Decreased performance Decreased body fat % D Decreased d VO2max Altered BP Increased muscle soreness Decreased muscle glycogen Altered HRrest (continued)
