VI,
a) normal sinus rytham is concidered to be normal anywhere between 80-100 for adults but the fitter you are the lower that is and even HR's lower than 80 (sinus bradicardia) are normal for a lot of quite fit people
b) the parasympathetic nervious system isnt like the sympathetic (ie VERY rapid onset), it takes a long time for it to regain dominance after sympathetic activation. Adrenilin as a drug for instance has a half life of 20-30 min after admistration IV so you can see that it will take a while for that to get out of your system. Actually a good example is vagal nerve (parasympathetic) stimulation (caroted massarge) for tachicardia. Its effects arnt seen for a good 15-20 min at least
c) stimulants on top of excersise can be quite dangerious. You risk the heart going into failure because its being told to do to much. If your excersising your ALREADY pumping adrenilin which binds to the alpha and beta 1 receptors and causes an increase in HR and contractability. Add caffinee on top of that...
d) fluid replacement is important, symple as that. So is salt replacement which can have effects on the heart, especially calcium and potassium highs and lows
a) normal sinus rytham is concidered to be normal anywhere between 80-100 for adults but the fitter you are the lower that is and even HR's lower than 80 (sinus bradicardia) are normal for a lot of quite fit people
b) the parasympathetic nervious system isnt like the sympathetic (ie VERY rapid onset), it takes a long time for it to regain dominance after sympathetic activation. Adrenilin as a drug for instance has a half life of 20-30 min after admistration IV so you can see that it will take a while for that to get out of your system. Actually a good example is vagal nerve (parasympathetic) stimulation (caroted massarge) for tachicardia. Its effects arnt seen for a good 15-20 min at least
c) stimulants on top of excersise can be quite dangerious. You risk the heart going into failure because its being told to do to much. If your excersising your ALREADY pumping adrenilin which binds to the alpha and beta 1 receptors and causes an increase in HR and contractability. Add caffinee on top of that...
d) fluid replacement is important, symple as that. So is salt replacement which can have effects on the heart, especially calcium and potassium highs and lows