B P4 C32 Exercise and Sports Cardiology Flashcards
The normal CV adaptations to exercise training include:
Resting bradycardia
Global cardiac enlargement
Functional pulmonic and aortic valve flow murmurs
Physical activity acutely increases systemic oxygen (O2) demand, which prompts the CV system to increase _____ and the _____.The increase in Q is coupled to the energy required such that there is a ____ liter increase in Q for each 1-liter increase in oxygen consumption (V” O2). Q is increased by augmentation of both the heart rate (HR) and stroke volume (SV).
Cardiac output (Q)
Arterial-venous (A-V) O2 difference
5-6 L increase for each 1L increase in O2 consumption
Several mechanisms increase the A-V O2 difference, including:
Shunting of blood from non-exercising tissue to working muscle
Increased O2 extraction by exercising muscle
Hemoconcentration
This increase in MO2 can produce ischemia in individuals with flow-limiting coronary artery lesions.
In addition, the coronary arteries _____ in response to the myocardial metabolic demands of exertion, but _____ develops with exercise in some individuals with coronary atherosclerosis because of endothelial dysfunction.
Dilate
CAD: Inadequate vasodilation or vasoconstriction
The _____ work rate is the VO” 2 required by the exercise task and, as mentioned, is a direct determinant of Q. V”O2 can also be crudely estimated from treadmill speed and grade or from a stationary bicycle watt requirement
External work rate
The _____ work rate refers to the myocardial oxygen consumption (MO2) required for the exercise task and relates directly to increases in HR.
Internal
Individuals with higher exercise capacity and a greater VO2max have a larger ____ at any given external work rate, such that any exercise task, and VO2 demand, requires a ____ HR to generate the same externally determined Q.
Larger SV
Slower HR
Repetitive aerobic exercise sessions and aerobic exercise training increase maximal exercise capacity, measured physiologically by an increase in VO2max. This increase in healthy individuals results from increases in both _________ and _________
Maximal Q and the maximal A-V O2 difference.
The reduction in ____ and thereby MO2 contributes to the increase in exercise capacity in patients with angina pectoris after exercise training.
Reduction in HR and MO2
In addition to the increase in maximal exercise capacity, exercise training also increases _____, the ability to perform submaximal effort for a prolonged period.This effect contributes critically to the exercise training response because few work or recreational tasks require maximal CV effort.
Endurance capacity
Intense and prolonged aerobic exercise training produces an array of CV adaptations, commonly referred to as “athlete’s heart”. Such changes include an _____.
Increase in resting SV
Decrease in resting HR
Characteristic adaptations during endurance training:
Mild to moderate eccentric LVH and RV dilation
Biatrial enlargement
Normal to slightly reduced resting LVEF
Normal or enhanced early LV diastolic function
Normal or enhanced LV twisting/untwisting
Characteristic adaptations during strength training:
Mild concentric LVH but no RV remodeling
Normal to mildly enlarged left atrial size
Normal to hyperdynamic resting LVEF
Normal or slightly reduced early LV diastolic function
Increase in late LV diastolic function
The physiologic mediators of training-induced reductions in resting HR are related in part to increased resting _____ and reduced resting sympathetic tone
Increased: Resting vagal tone
Reduced: Resting sympathetic tone
Highly trained endurance athletes often develop resting bradycardia, which may be associated with _____.
Marked sinus arrhythmia
First-degree heart block
Mobitz I second-degree AV block
Third-degree AV block during sleep
The _____ AV conduction velocity may make accessory conduction pathways, such as those of Wolff-Parkinson-White syndrome, more apparent
Reduced AV conduction
Athletes also have an increased prevalence of an ____ and ____, ECG findings also historically attributed to increased vagal tone
Early-repolarization ST-segment pattern
ST-T wave abnormalities
Cessation of exercise training, or “detraining,” may help in clinically differentiating adaptations to exercise training from _____.
Hypertrophic cardiomyopathy (HCM).
Regression of eccentric LVH can occur in highly trained athletes after _____ weeks of abstinence from exercise.
6 to 34 weeks (mean, 13 weeks)
Because the LV wall thickening and concentric LVH common in strength-trained athletes can regress partially after _____ months and completely after _____ months of detraining, such diagnostic trials should last 6 months.
3 months: Partial
6 months: Complete
Multiple epidemiologic, cross-sectional studies examining the frequency of CV events in healthy individuals demonstrate that the more active participants have lower CV risk than their more sedentary counterparts.
The reduction in risk in the most active versus the least active individuals is approximately ___%
40%
Even small amounts of physical activity reduce CV risk. CV risk falls progressively with increasing physical activity until approximately ____ hours per week of moderate-intensity activity, such as brisk walking.
After this level of exertion, there appears to be little additional benefit and, possibly diminution, of the beneficial effects.
9.1 hours
None of these studies was large enough to provide conclusive results alone, but a meta-analysis of 63 RCTs including 14,486 patients demonstrated a __% decrease in CV mortality in the patients assigned to the exercise-based programs.
26%
Epidemiologic data suggest that the largest reduction in CV risk with physical activity occurs at _____ levels of activity.
Consequently, current American guidelines recommend _____ weekly of moderate aerobic activity such as brisk walking or _____ weekly of vigorous activity such as jogging, plus some resistance exercise twice weekly.
Low
150 to 300 minutes/week
75 to 100 minutes/week