Final answer:
Mason should increase the pace of his runs to reach his target heart rate zone of 138–183 beats per minute to maximize cardiovascular benefits during exercise.
Step-by-step explanation:
To get the most benefit for his heart during his water polo conditioning, Mason should adjust his intensity to reach his declared target heart rate zone of 138–183 beats per minute. Given that Mason's current heart rate during his 25-minute run is 125 beats per minute, he should increase the pace or intensity at which he is running. A higher intensity workout will increase Mason's heart rate, thereby improving cardiovascular fitness as his heart will work harder within a safe and effective range known as the aerobic zone. According to health guidelines, maintaining a heart rate within the target heart rate zone during aerobic exercise will maximize the benefits to both the heart and lungs.
The recommended target heart rate is between 120 and 160 bpm for maintaining cardiac output (CO). Since Mason's age isn't provided, we can't calculate his maximum heart rate, but as long as he is within his target zone, it will be beneficial. To monitor progress and ensure safety, Mason can use a heart rate monitor during exercise and aim to slowly increase his running pace until his heart rate falls within the target zone.