I would like to share with you one of my favorite racing tips.
All you need to do is use turn signals when you are rounding a corner during a race or group run.
It amazes me is that you do not see very many people employ this strategy.
There are 3 reasons that I love using turn signals:

1. You will be running with courtesy against your fellow racers
2. You will be less likely to hurt or be hurt by somebody trying to pass you
3. You will gain a small competitive advantage.
   

While this does not apply to running on a track, most road races and cross country races involve making at least a few turns.
If you take a slightly wider angle when you reach those turns you can keep up your momentum and lose less speed.
The problem with that is that your competitors may try to cut you off and run to the inside on the turn.
Not only do you not want them jumping in front of you, but it becomes very easy to clip each other's heels or to run right into one another.
Every once in a while you will come across somebody who does not even know there is a turn there and will keep going straight while you make the turn in front of them, resulting in a collision.
It does not happen very often, but especially on a spread out course it is not unheard of.
The simple solution is to hold your arm out in the direction that you are turning.
By doing so you will reserve the space to your right or left with your arm, which keeps people from cutting to the inside since most runners will not intentionally run into you.
You will maintain your position in front of them around the turn while at the same time warning them that you are about to make that turn.
The small amount of momentum that you lose is more than evened out by not having to slow down to take a tighter turn or having to swing wide after the turn.
You do not need to hold your arm out for very long; if you are thrown off balance then you held your arm out for too long.
Just swing your arm out as you pump your arms and make the turn.
You should be around the corner fast enough that you will not feel held up at all by using your turn signal.
Remember not to swing you arm violently to the side.
Not only would this be counter productive and more likely to throw you off balance, but you do not want to hit anybody that does happen to be next to you.
This also works well when you want to cross from one side of the road to another to get to a water stop during a race.
So remember, by being polite and courteous to your fellow runners, you prevent them from passing you on the inside or causing a collision.
And, you get a competitive advantage.