A tempo run is designed to improve a runner’s lactate threshold. During easy running, your body breaks down sugars to fuel the muscles, which produces lactic acid. When running easy, the body recycles lactic acid back into energy and efficiently expels the waste products. As you continue to run faster and demand more energy, the production of lactic acid will slowly increase. The point at which your body produces more lactic acid than it is able to reconvert back into energy is referred to as your lactate threshold. A tempo run requires running slightly slower than the body’s lactate threshold, so that you train your body to increase its ability to reconvert lactate back into energy. Tempo runs extend endurance and the ability to maintain a faster pace over longer races like the 10Kand the half marathon.
Why running faster during a tempo run is detrimental:
When you push too far beyond your lactate threshold pace, you prevent your body from learning how to effectively clear lactate. Instead of becoming more efficient by handling a moderate and consistent amount of lactate, your body is flooded. It isn’t able to benefit from a prolonged period of lactate clearance. By speeding up, you don’t achieve the benefits of the workout and actually walk away from your tempo run less fit than you would have by staying on the prescribed pace.