You are making wrong comparisons.
1) How do you know those who collapsed are all trying to clock a
better timing? Quite likely that they are not doing so, yet still
collapse
2) Play safe and stop when cannot stop, it is obvious. However,
there's a reason for using progressive training. You should not
wait till a test comes before testing your limit.
Lastly, how are your consistent trainings like? Which trainings
helped you increase your VO2 max and strengthen your heart? FYI, it
is a scientific fact that most people actually breathe mainly
through 1 nostril, with the other nostril taking less air. In
addition, during cardio, you could breathe through your mouth too.
Finally, if you really had a serious problem, you could always get
the MO to downgrade.
