[IkmoIkmo]

And yet professional boxers regularly gas after 5 rounds of 3 minutes... Now add equipment, particularly armour.

Or look up a Judo match, particularly during tournaments. You can see these guys are often wrecked after a particularly long match, and typically matches last only a few minutes. Just see Judo matches in the last Olympics, guys who typically have 3 to 5 training sessions a day, 7 days a week, for 2 decades.