Your heart rate is a great indicator for overall cardiac health. Your heart is essentially a muscle and it beats to send blood, oxygen and nutrients to your muscles, so your muscle can keep doing whatever physical exercise you are doing. The more aerobically conditioned you are the slower you heart beats.
I didn’t say the more exercise you do automatically increases your aerobic capacity.
The more intense your physical activity – the faster your heart needs to beat. The basic goal of aerobic training is to expand your ‘aerobic’ capacity, your aerobic threshold – so your red blood cells can carry more oxygen. Think of it like a bucket brigade that is needed to carry water to put a fire out. The more aerobically conditioned you are the bigger the bucket of water (oxygen) you can carry to the fire. The less conditioned individual or coach potato, who has a lower aerobic threshold will deliver as many buckets to the fire, but his bucket carries a lot less water (oxygen). Essentially, his buckets are smaller and can’t carry as much.
The point I am trying to make, and why ‘proper’ aerobic training is so important – is the fact that the less conditioned person doesn’t carry as much water (oxygen) in his bucket. Therefore, his bucket brigade needs to move faster in order to transport the same amount of water (oxygen) to the fire (those burning muscles). So, to get more oxygen to those burning muscles, your heart needs to beat faster in order to carry the same amount of water (oxygen) to those burning muscles. So, the more aerobically conditioned you are the slower (the less) your heart needs to beat – in order to carry the same amount of blood and oxygen.
Aerobic exercise is low intensity that you can do for long duration. Just because you can jog 3-5 miles doesn’t mean you used your aerobic system, you could have been jogging at a pace that is a little to fast for your level of conditioning and activated your anaerobic system. This is stress producing on your body and uses carbohydrates and proteins (lean muscle) for energy, Instead of FATS!
The bottom line is ‘proper’ aerobic exercise makes your heart more efficient at transporting oxygen throughout your body. Therefore, your heart muscle has to work less and beats less, which is a good thing. So, make sure you include some aerobic training in your daily life – and don’t make the classic mistake that 80-90% of the population makes when it comes to aerobic training….which is to walk, jog, run, bike, swim, dance, etc….too fast for what they are aerobically conditioned for.