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A cardiac stimulant is a drug which acts as a stimulant of the heart – e.g., via positive chronotropic action (increased heart rate) and/or inotropic action (increased myocardial contractility). They increase cardiac output (the amount of blood pumped by the heart over time).
A medical monitoring device displaying a normal human heart rate. Heart rate is the frequency of the heartbeat measured by the number of contractions of the heart per minute (beats per minute, or bpm). The heart rate varies according to the body's physical needs, including the need to absorb oxygen and excrete carbon dioxide.
The sympathetic nervous system is a part of the nervous system that prepares the body for action, such as increasing the heart rate, blood pressure, and breathing rate. Stimulants can activate the same receptors as the natural chemicals released by the sympathetic nervous system (namely epinephrine and norepinephrine) and cause similar effects. [7]
The mechanisms of sympathomimetic drugs can be direct-acting (direct interaction between drug and receptor), such as α-adrenergic agonists, β-adrenergic agonists, and dopaminergic agonists; or indirect-acting (interaction not between drug and receptor), such as MAOIs, COMT inhibitors, release stimulants, and reuptake inhibitors that increase the levels of endogenous catecholamines.
A common artificial sweetener may trigger insulin spikes that lead to the build up of fatty plaques in the arteries, increasing the risk of heart attacks and strokes, a new study in mice indicates.
Caffeine is a mild diuretic, which can often lead to dehydration. Other physical disadvantages include, impaired fine motor control, observed via the shakiness of athlete's hands, gastrointestinal upset, increased heart rate and sleep disruptions. [9]
[citation needed] The heart rate formula most often used for the Bruce is the Karvonen formula (below). A more accurate formula, offered in a study published in the journal, Medicine & Science in Sports & Exercise, is 206.9 - (0.67 x age) which can also be used to more accurately determine VO2 Max, but may produce significantly different results.
Combining dextromethorphan with other substances can compound risks. Central nervous system (CNS) stimulants such as amphetamine and/or cocaine can cause a dangerous rise in blood pressure and heart rate. CNS depressants such as alcohol will have a combined depressant effect, which can cause a decreased respiratory rate.