Because when your muscles are working they need more oxygen and nutrients, which they get from the blood. And for the blood to be able to carry more nutrients to the muscles the heart has to pump faster.
The nervous system causes the heart to beat faster when you exercise. It itself is not an organ but a system.
No, the heart beats faster during exercise. The liver doesn't beat at all.
because the blood system is working harder
As you exercise, the muscles need more oxygen to work. The heart beats faster to get the oxygenated blood from the lungs to the muscles. The harder you exercise, the more oxygen the muscles need, the faster the heart beats.
Your heart starts to beat at faster rate. The heart rate may go up to 180 beats per minute.
strength training
It's not good at all.
because when you exercise your muscles require more oxygen so your heart will beat faster to get the oxygen to the mucsles. since your blood goes through the lungs and your heart is beating faster you must breathe faster to get a sufficient amount of oxygen.
because when you move you need more and more blood so your heart has to beat even faster
the more you exercise, the faster your heart beat is. this type of exercise is called cardiovascular exercise. (cardio for short) this strengthens your heartbeat. exercise makes the heartbeat faster because for example: the faster you run, do you notice you panting? your body needs all the oxygen it can get when exercising.
You can infer that your (healthy) heart is beating faster to compensate for the extra effort your body is making during physical exercise. Once the exercise is over, the time the heart takes to become relaxed and to return to a normal resting beat is a good indication of the state of the health of your heart.
The more you exercise - the more oxygen your body's muscles need. In order for your heart to supply more oxygen - it must beat faster.