Your training runs should be premeditated to achieve particular goals. Tempo runs work to advance your stamina by pushing your lactate threshold, thus letting you build up to working out longer before getting fatigued. Steady state or "infinity pace" runs are harder than your recovery runs, but easier than your tempo runs. Steady state runs require you to go longer than a tempo run, and help to work on your endurance. Together, tempo running and steady state running will help you to run faster, longer and more efficiently.
Push Your Lactate Threshold
A tempo run is a fast-paced running session. When you're doing tempo runs it is important to use your warm up in order to ramp up to your tempo pace. If you average 20 miles per week, your tempo run day might have you going a total of six miles, with three of those miles being at your tempo pace. You will probably notice that you approach or reach your lactate threshold, which is the exercise intensity at which your body no longer processes lactic acid. A lactic acid buildup can result in temporary muscle soreness and the dreaded "side stitch." As you complete more tempo runs and push your body's lactate threshold further, you'll be able to run longer and at a faster pace, without experiencing side stitches and muscle fatigue.
Your tempo running pace is going to be specific to your fitness level and pace goals, but should be comfortably hard. Generally, your tempo running pace will be around your 10K (6.2 miles) race pace, or up to 22 seconds slower than your 10K pace depending on the duration of your run. If you haven't run a 10K recently, just do a time-trial using a known distance. Your heart rate during tempo runs will be around 85-90 percent of your max heart rate.
Push Your Endurance
Steady state running is designed to push your endurance. Your steady state is the one that you can maintain for "infinity," or at least one hour. During a steady state run, you will run at an effort that is fairly comfortable, though not quite as comfortable as an easy run. It will push your endurance so that instead of becoming fatigued from the intensity of your run, you'll actually become fatigued from your duration.
Steady State Pace
Your steady-state pace should be between your current 30K and half marathon pace. You should be capable of running at a steady-state pace for 25-75 minutes, and your heart rate should remain fairly consistent and between 83-87 percent of your maximum heart rate. To determine your steady state pace, you can do some timed running trials on an out-and-back course. The amount of time it takes you to run back should be the same as the amount of time it took you to run out. If it takes longer, you started too fast; if it takes less time, you started too slow.
Ari Reid has a bachelor's degree in biology (behavior) and a master's in wildlife ecology. When Reid is not training to run marathons, she is operating a non-profit animal rescue organization. Reid has been writing web content for science, health and fitness blogs since 2008.