If 33-Year-Old Jacob Is Cross-Training and His Current Heart Rate

Multiple Choice

If 33-year-old Jacob is cross-training and his current heart rate is 137 beats/min, exercising at his current level of exertion _____.

A) could potentially be dangerous for a non-athlete of his age
B) is not intense enough to improve his cardiovascular fitness
C) will help improve his cardiovascular fitness
D) is appropriate for a competitive athlete in training