There are multiple factors that affect your heart rate and rhythm, and I strongly encourage you to discuss the full details of your situation with your primary care physician
. In situations when our body's organs require additional oxygen, our heart beats faster to provide this need. This response can also be triggered by pain, anxiety
, or fever.
Your heart contains its own electrical system that controls heart beat. This electrical system is also influenced by outside signals. For instance, signaling from your parasympathetic nervous system via your vagal nerve can decrease your heart rate. Additionally, when you take a deep breath, your right ventricle is able to fill with more blood than usual. This will lead to more blood being ejected with the subsequent heart beat, which you may be able to sense. Positioning yourself in awkward positions may also affect the pressure within your thoracic cavity, which also affects right ventricular filling. Finally, the mechanisms you describe of squeezing your muscles is most likely causing a valsalva response. This can also increase vagal nerve signaling and affect your heart beat.
An abnormal heart beat in some cases may represent an arrhythmia, such as atrial fibrillation. In some cases, these arrhythmias can be life threatening. I encourage you to discuss your symptoms with your primary care doctor
. After a thorough history, physical exam, and EKG, it is possible you may need to undergo additional testing.