can put stress on the heart muscle.
LIFTING HEAVY WEIGHT
TRAINING TO OFTEN
HOLDING YOUR BREATH

LIFTING HEAVY WEIGHT i believe this is the answer its either this or holding your breath but this is more likely to be the answer :)

Explanation:

relationship between pressure and air volume and led to the understanding of how respiration works; i believe this is the correct answer ; /// good luck

for respect usually. some people might be little awkward if you meet or some would be different. usually   you dont love people when you meet them depends on the type of person.

hope this