Suggest Treatment For Heart Palpitations
an ECG or 24h Holter is required
since your pulse seems to be irregular an ECG will clarify everything. The relation to your stance is strange. I don't believe there is a true relationship with that - it has to be coincidental. If this arrhythmia comes and goes then a 24h Holter study may detect it. I can't make any guesses about the type of arrhythmia though. There are harmless and dangerous types of arrhythmias. Some of the harmless ones may be related to anxiety, thyroid disease, dehydration, electrolyte disorders etc. If a true arrhythmia is detected then a more detailed assessment will have to be arranged.
I hope you find my comments helpful!