Please choose the correct ending to complete the given sentence: Sports and Fitness: [header] How to run 1600 m track relay [title] Explode from the start. [step] The opening of the race is incredibly important and contributes to the success of the relay. If you are the first runner in the relay, you will need to set the pace and tempo for the rest of your team.

Ending1: [substeps] Aim to have a consistent pace for every mile you run. As the race progresses you will need to train side-to-side for excellent speed changes. Ending2: [substeps] Try not to make it so easy on yourself--if you are the runner, imagine running 80 miles (950 km) in one minute. You would not get how tough it would be if the event affected your entire team. Ending3: When you begin running, there will be a seven-second timeframe where your body will not have a buildup of lactic acid, and you can take advantage of this to gain speed without getting fatigued. Blast off as fast as you possibly can and then work on gaining more momentum as you run. Ending4: [substeps] Clear the track by going over it 180 degrees. Once you have cleared the track, cross it and walk somewhere safe, like a sidewalk.

Answer format: ending1/ending2/ending3/ending4