Are you running several times a week, but don't seem to be getting anywhere? Slowing down? Endurance waning?
Your body eventually acclimates to a particular pace and/or distance. So overtime, you won't get what you used to out of that regular 5-miler every other day. Stagnation sets in. So what's a runner to do?
Easy! Spice it up with a tempo run. A tempo run is basically a fast run, but just trying to run fast from start to finish usually isn't very effective. Like most things, a little structure to these "faster runs" will provide you with the results you're looking for.
Every run doesn't need to be a tempo run. That will only increase your chance of overtraining and injury. It's hard to believe, but just adding one tempo run to your weekly routine will quickly begin to increase your speed and endurance.
How does it work? Tempo runs help push out your lactate threshold (that burn you feel in your legs when you run fast). Tempo workouts teach your body to more quickly clear out the lactate buildup delaying or preventing that fatigue-causing burn.
Tempo runs also help increase your VO2Max (your body's ability to take in oxygen and use it to make energy in the muscle). Continued use of tempo runs actually signals your body to make more capillaries in the muscle. More capillaries means more oxygenated blood getting to the muscle.
The distance of tempo runs can vary, but 4-8 miles is a good range. If you're new to tempos, start with a shorter distance and work your way up.