Glossary · Training
Interval training
Interval training alternates periods of hard effort with periods of easy recovery. Splitting the hard work into repetitions lets you spend more total time at a high intensity than you could in one continuous effort.
Common types
Threshold intervals (for example 4 × 8 minutes at threshold with 2 minutes' recovery) raise sustainable speed. VO2 max intervals (5 × 3 minutes hard with 3 minutes easy) raise your aerobic ceiling. Short speed reps (8 × 30 seconds fast with full recovery) sharpen economy and leg speed.
How much to do
Two hard sessions a week is plenty for most endurance athletes, with easy days in between. The recovery between reps is part of the workout: cut it short and the session drifts into a different one.