Are abdominal aortic aneurysms more likely to burst during extreme physical exertion?

Anytime. Not particularly although weight lifting and raising ones blood pressure very high could theoretically contribute. More by size and constant high blood pressure. Greater than 5.5 cm. Abdominal infra renal is concerning. Smaller are followed by exam and/ or ultrasound exams( or ct which is more expensive and radiation.
Yes. Because of elevated blood pressure. But it can happen any time. Once it ruptures, chance of death increases by a lot, so it is better to have it resected or repaired if your surgeon suggests it.