Please choose the correct ending to complete the given sentence: Education and Communications: [header] How to measure vo2 max [title] Determine your resting heart rate. [step] Many fitness trackers and watches come with a heart rate monitor. If you have one of these, record your heart rate while at rest (sitting down, doing little-to-no physical activity).

Ending1: Record the reading as accurately as possible so as to accurately follow the human's body temperature and blood pressure, lifestyle, health, and activity. [substeps] Note that although these readings may be astronomical in quality, they require real data to be reasonable. Ending2: On average, this should be around the level of 140 beats per minute. Watch to see how your heart rate changes per minute. Ending3: The best time to measure your resting heart rate is in the morning before you get out of bed. [substeps] To determine your heart rate without a monitor, place two fingers against the artery on the side of your neck, just under your jaw. Ending4: Note that if your heart rate is not elevated within 1 to 2 minutes of your rest, it's fairly normal. [substeps] If you don't have your heart rate or watch the tracker, keep a notebook or app on your phone and record down how long your heartbeat has been going on.

Answer format: ending1/ending2/ending3/ending4