LACTATE INTERVALS Lactate intervals take the form of relatively short to moderately long intervals (600–1,200 m) run in the range of 5K race pace with easy jogging recoveries between them. They’re an excellent means of progressively developing efficiency and fatigue resistance at fast running speeds. The more challenging versions of these workouts are very stressful and yield results quickly, so competitive runners typically focus on them for a relatively short period of time in the heart of the training cycle. Shorter-distance racers usually place this period toward the end of the training cycle because it builds race-specific fitness, whereas longer-distance racers usually focus on lactate intervals a little earlier in the training cycle because they are less race specific. Example 1 mile of easy jogging (warm-up) 5 × 1 km at 5K race pace with 400 m jogging recoveries 1 mile of easy jogging (cooldown) SPEED INTERVALS Speed intervals are short or relatively short intervals (100–400 m) run at roughly 1,500 m race pace or faster. They boost speed, running economy, fatigue resistance at fast speeds, and pain tolerance. Distance runners typically use shorter, faster intervals earlier in the training cycle to increase their pure speed and then move to slightly longer, slower (but still very fast) speed intervals to add fatigue resistance to their speed. Example 1 mile of easy jogging (warm-up) 10 × 300 m at 800 m race pace with 400 m jogging recoveries 1 mile of easy jogging (cooldown) MIXED INTERVALS Mixed intervals, as the name suggests, are intervals of various distances run at different pace levels. Mixed-interval runs are an excellent means of including a variety of training stimuli within a single workout. They can be used earlier in a training cycle as the primary high-intensity training stimulus of the week or late in the training cycle as a stimulus that is secondary to another high-intensity workout that is focused on a single, race-specific intensity.