In terms of cardiovascular changes associated with resistance training and aerobic training, one must think in terms of forces the heart faces.
In aerobic exercice, the heart increases its heart rate, its stroke volume and oxygen uptake. Therefore the stress faced is in aerobic exercise is volume-load. The compensatory mechanism being improved mechanical coupling at a molecular level for myofiber contraction, improved preload (initial stretching of the fibers like a spring, generating more force when it contracts) and asymetric hypertrophy (the ventricular wall enlarges more than the septum (the wall between the right and left ventricules). This leads the the heart to be a more physiologically efficient pump. Since Cardiac Output (in Liters of blood pumped per minute) = Heart Rate X Stroke Volume, a heart with increased stroke volume secondary to improve coupling/ asymetric hypertrophy requires a lower heart rate to maintain a same output.
Therefore, lowered heart rates are expected in aerobically more fit individuals since the heart has been trained.
In resistance training, the general human habit is to generate muscular force while performing a Valsalva manoever (trying to push air out without breating out), both these actions increase intrathoracic pressure which reduce venous return (pressure in the thorax is too great for blood to come back to the heart). This can be strong enough for people to loose consciousness momentarily when defecating. To combat this the heart increases heart rate (to maintain cardiac output) and increase vasoconstriction to maintain blood pressure. Once you let the air out and stop contracting (racking to bar and breathing after a squat) the venous blood ‘‘blocked’’ in the abdomen and lower body returns to the heart (which is beating faster) and is pushed toward a vasoconstricted system which increases the pressure that the heart must fight against to push blood through the system. This can take a few minutes to return to baseline.
Therefore resistence training is a pressure-load on the heart which leads to symetric hypertrophy with no changes in the diameter of the ventricules. So the heart here adapts to fight against pressure and not volume, therefore a drop in baseline heart rate is not expected as physiological adaptations to increase cardiac output where not present. However, the heart is not adapted to deal with higher pressures therefore, in subsequent bouts of submaximal resistance training, the HR needed to maintain cardiac output in a higher pressure system is lower and blood pressure is also slighlty lower.
So basically, type of training affects the heart physiology as a function of the forces it faces.
In terms of cardiovascular health, aerobic exercice increase cardiac pump efficiency the most.
Resistance training tends to ‘‘keep’’ up with muscle mass with either no benefits to cardiovascular fitness (outside of those that are secondary to reduced bodyfat, improved metabolism and so on) or minimal benefits, more importantly though, is that there is no adverse effects to that physicological hypertrophy induced hypertrophy.
Caveat: This would not apply to someone using AAS with resistance hypertrophy as AAS have a tendency to increase BP for relatively long periods of time, as opposed to the short bouts of elevated BP facing the non-AAS using athlete. This is simply because the heart has a very hard time adapting to chronic pressure-load and does so in a pathological manner (eccentric hypertrophy with loss of efficient contractility (leading to heart failure) and eventual difficulties wiht cardiac tissue oxygenation (leading to MI or ischemic cardiomyopathy.)
Hum, this was supposed to be short.
Basically, I’ll have to go with Lorisco on this one, one who is cardiovascularly fit would have a lower heart rate.
You might look fit, but it does not imply that the cardiovascular system is particularly trained ((I look much more fit when I weight train then when I run marathons, but my HR and my BP say otherwise).
Also, we can’t rule out other reasons why you HR might have been lower prior.
AlexH