1. The heart rate, stroke volume, and cardiac output of trained individuals can increase to a greater extent during maximal exercise compared to untrained individuals. This allows trained athletes to consume more oxygen and delay the onset of blood lactate accumulation.
2. Long-term aerobic exercise training results in lower resting and submaximal heart rates, an increased blood volume and plasma volume, and higher maximal stroke volume. It also increases lung volumes and the body's ability to extract and use oxygen.
3. Abnormal cardiorespiratory responses to exercise, like a low maximal heart rate, falling systolic blood pressure, or rising diastolic blood pressure, may indicate underlying heart disease. Ischemia can impair
2. HEART RATE
• Reflects the amount of work the heart
must do to meet increased demand
• Resting Heart Rate
– Averages 60 - 80 b/min
– 30 (highly trained) to 100 (sedentary)
– anticipatory response
• Exercise Heart Rate
– linear relationship with Oxygen Uptake &
Workload
3. • Maximum Heart Rate (MHR)
– highest heart rate you achieve in an all-
out effort
– estimated by MHR = 220 - age
• Steady State Heart Rate
– optimal heart rate for meeting the
circulatory demands at a specific work
rate
– can increase during prolonged exercise
& heat stress
– indication of fitness level
5. STROKE VOLUME
• DETERMINED BY
– Volume of venous return
– Ventricular Distensibility
– Ventricular Contractility
– Aortic or Pulmonary Artery Pressure
6. STOKE VOLUME INCREASES
WITH EXERCISE
• Almost doubles until 40 - 60% of
maximal capacity
• Mechanisms of Increase
– Frank-Starling Mechanism
• greater ventricular stretch = greater ventricular
contraction
– Increased Ventricular Contractility via
stimulation
7. CARDIAC OUTPUT
• Linear Relationship between cardiac
output and work rate/oxygen
consumption
• Effort to meet the muscles’ increased
demand for oxygen
8. REDISTRIBUTION OF
BLOOD FLOW
• At Rest 15-20% of Q goes to skeletal
muscle
• During heavy Exercise this increases
to 80 to 85%
• Redirected through action of the
sympathetic nervous system
• Overall Vasoconstriction & Local
Vasodialation
9. Control of Pulmonary
Ventilation During Exercise
• Immediate-Marked Increase
– Initiated by Motor Cortex
– Assisted by feedback from working muscle
• More Gradual Rise
– Result of changes in Temperature and
Chemical Status (i.e. chemoreceptors)
– Levels off between 100-160 L.min-1
• Recovey Mirrors Exercise
10. Breathing Problems During
Exercise
• Dyspnea
– shortness of breath
• Hypeventilation
– sometimes intentional
• Valsalva Maneuver
– Closes Glottis
– Increased intra-abdominal and intra-thoracic
pressures
– reduces volume of blood returned to the heart
– increases TPR
11. Ventilatory Breakpoint
• Disproportionate Increase in VE
as compared to increase in VO2
• Result of accumulation of H+
and CO2 in blood
• Sometimes observed in VE/VO2
measure
• The same as Anaerobic
Threshold ?
12. Ventilation Limiting
Performance
• Typically not in Normals
• Possibly in Highly Trained
Subjects
• Likely in COPD
• Environment can influence the
role of ventilation in performance
14. MAXIMAL OXYGEN
CONSUMPTION
• VO2max = Aerobic Power
• Highest Rate of Oxygen
Consumption attainable during
maximal exercise
• “Gold-Standard” of assessing
Fitness Level
15. VO2max
• VO2 increases with increasing
workload until plateau
• Average 20% increase following 6
month training program in
previously untrained
• Absolute = L.min-1
• Relative = ml.kg-1.min-1
16. • Average College-Aged Female = 40-45
ml.kg-1.min-1
• Average College-Aged Male = 45-50
ml.kg-1.min-1
• Highly-Trained Female = 60-70 ml.kg-1.min-1
• Highly-Trained male = 65-75 ml.kg-1.min-1
VO2max
18. HEART SIZE
• Increased Heart Weight and Volume
• Increased Left Ventricle wall thickness
and chamber size
• Athlete’s Heart
• Endurance versus Resistive Exercise
19. Training and Heart Rate
• Resting Heart Rate
– decreases markedly (1 beat per min per week)
– increased parasympathetic, decreased sympathetic
• Submaximal Heart Rate
– lower heart rates at a specified work rate
– heart becomes more efficient
• Maximum Heart Rate
– may decrease slightly
20. Stroke Volume
• Increase in Both Resting and
Maximal SV
• Due to:
–Increase in Plasma Volume
–Increase in Elastic Recoil of LV
–Increase in LV contractility
22. Heart Rate Recovery
• Heart Rate Recovery Period is
shortened by training
• Can be used as an index of
cardiorespiratory fitness
• Effected by heat stress &
altitude
23. Cardiac Output
• During Resting and at Absolute
Submaximal Workloads it
doesn’t change much
• Increases significantly at
maximal exercise
• Mainly due to increase in
maximal Stroke Volume
24. Blood Flow
• Increased capillarization of trained
muscle
> capillary to fiber ratio
• Greater Opening of Existing
Capillaries
• More effective blood
Redistribution
25. Blood Pressure
• Changes little during standardized
submaximal and maximal exercise
• “Exercise Only” typically has little effect
on Resting Blood Pressure
• Weight is more of an issue
• Borderline Hypertensive’s
• Aerobic vs Resistive Exercise Training
26. Blood Volume
• Exercise Training increases Blood
Volume
• Due to Increase in Plasma Volume
• Two Mechanisms
– Increased release of Antidiuretic Hormone
(ADH) and Aldosterone
– Increased amount of plasma proteins
(Albumin)
27. Red Blood Cells
• Hematocrit is Typically Reduced
– reduces viscosity of blood
– A cause for anemia ?
– Effect on Performance
• Absolute amount of Red Blood Cells and
Hemoglobin Increases
• Blood Doping
29. Respiratory Adaptations
• Lung Volumes
– Vital Capacity slightly
– Residual Volume slightly
– Tidal Volume
• Respiratory Rate
– Lowered at Rest and Standardized Submaximal
Workloads
– Increased at MAX
• Pulmonary Ventilation
– Maximal is greatly increased
• Pulmonary Diffusion
– Increased during maximal exercise
– Better Pulmonary Blood Flow
30. Arterial-Venous Oxygen
Difference
• Increases with training particularly
at Maximal levels
• Lower Mixed Venous Content
• Due to:
– Greater Oxygen Extraction
– More Effective Blood Distribution
31. Lactate Threshold
• Increased - Able to perform at a higher
rate of work without increasing Blood
Lactate Levels above Resting
• Due to:
> ability to clear lactate
Shift in preference for metabolic substrates
32. Resting Oxygen Consumption
• Typically Increased
Slightly
• Due to:
– Increased Muscle Mass
– EPOC
• Return to Homeostasis
• Thermoregulation
• Clearance of Waste Products
• Adaptations
33. Submaximal Oxygen
Consumption
• Locomotive Economy/Running Economy
• Elite versus Novice
– Shows improvement
• Longitudinal Data
– Shows no change
• What is Going On ?
– Becoming more skilled
– Becoming more efficient physiologically
– Shifting Substrate Utilization to Fat
34. Maximal Oxygen
Consumption
• Initial Level of Conditioning
– the higher the initial state the lesser the
increase
– Highest attainable VO2max reached in 8 to 18
months
• Reasons for Increased VO2max
– Increased Oxidative Enzymes in the Muscle
– Improved Delivery of Oxygen to the Muscles
• i.e. improved blood flow
35. Factors Affecting the Response
to Aerobic Training
• Heredity
– responders versus
nonresponders
• Age
• Gender
• Specificity of Training
42. Symptoms Associated With
Fall in Systolic Blood Pressure
• Shortness of Breath
• ST Segment Changes
• Angina
• Pallor
43. Mechanisms of Abnormal BP
Response
• Ischemic of Scarred Ventricle will
quickly achieve maximal SV
• Consequently, Cardiac Output will not
increase as much
• As a result SBP may decrease due to
reduced Periferal Vascular Resistance
44. Diastolic BP Abnormality
• Persistent Rise in Diastolic Pressure with
increases in exercise workloads
– 15-20 mm Hg or greater
– May Be indicative of CAD without ECG
changes
– Reduced Coronary Artery Blood Flow
• Drop in Diastolic Pressure
