As an “adult-onset” competitive runner (to borrow Salty’s phrase), I am admittedly a newbie in regard to the best use of interval running to achieve specific adaptations leading to performance gains. Every coach has their favorite interval workouts, and the intricacies of each involve targeting specific physiologic effects I am only just starting to understand. However, I recently completed USA Track & Field Level One Coaching School, and the introduction to coaching “The Endurance Events” lecture at least started to clarify some things about interval training for me, which I will now share with you.
One important point that came out during the course was the difference between interval running and repetition running. The keys to interval running are short bouts of running and incomplete recovery. In fact, you should only give yourself about one-third the amount of rest you would need to feel fully recovered from the bout of running you just completed. So, for example, if your interval workout was 12 x 400 meters in 75 seconds/400 meters bout, and you would need 6 minutes to completely recover from each 400 meter effort, you might only give yourself 2 minutes of rest. According to the USATF and Coach Fred Benlein (the director of the Level One School I took), the volume of this kind of workout should be high, up to twice the race distance, but the intensity of each running bout should be low enough so the full volume of the workout can be completed.
In contrast, repetition running involves longer bouts of running at high intensity, but the key in this case is complete or near-complete recovery. Each repetition should be up to two-thirds the goal race distance and should be run at or near race pace. The total volume here should be two-thirds to twice the goal race distance, and the purpose is to train the athlete to run in the “critical zone” – running that requires both the aerobic and anaerobic energy systems. An example of repetition running is 3 x 1 mile at goal 5K race pace with 5-10 minutes rest between mile repeats. A coaching pearl that Coach Benlein shared with us is that commonly people don’t give themselves enough rest between mile repeats, and this makes recovering from this type of workout difficult. However, if you give yourself long recovery periods between repeats, this allows you to practice running at race pace without accumulating so much fatigue you can’t recover in time for your next planned stimulus.
Finally, I will share with you a really neat interval workout Coach Benlein taught us, which I have started to include regularly in my own training schedule: the Neuromuscular-Based Regeneration Run. Coach Benlein developed this workout on the idea that recovery days should target the musculoskeletal, neuromuscular and energy systems, not the cardiovascular system. In other words, just because your body needs rest and recovery doesn’t mean you can’t give your heart and lungs a workout. The workout is this: 20 x (30 seconds hard, 30 seconds easy); Coach Benlein has his athletes do this workout on the day before their hard days. The hard intervals should be run at around 1 mile/1500 meter pace, a pace above VO2 max, which keeps the heart and lungs working hard for the duration of the workout, as the recovery time is very short. However, because of stride efficiency at this pace and the short duration of each hard interval, the legs do not build up significant waste products during the workout. So you can recover easily and run again, feeling fresh, the next day!
I started including this workout on the day before my long runs. I do it on the track, running hard for 150 meters in 30 seconds, and then jogging or walking 50 meters for my 30 seconds of recovery. I have to admit, so far I’m only in shape to do ten reps, but I’m hoping to work up to twenty. And Coach Benlein is absolutely right – my legs have been fine the next day and with no adverse effects at all on my long run.
Do you have a favorite interval workout? How and when do you use interval training in your own training schedule?