Interval training is one of the more misunderstood terms in fitness. When most people think of interval training they think of its super popular form HIIT. You know the one that makes you want to puke and shit your pants at the same time but everybody in the class smiles as they collapse after a few intervals or run around madly high-fiving? Interval training is so much more than that. It’s actually far less scary if you know a little more about it. It doesn’t have to be super high intensity.
“Interval training is as hard as it needs to be… for that client.” – Mike Boyle
I’m almost embarrassed to say it but it took me years to completely get on board with interval training as my primary method of cardiovascular training. I always justified going for long runs or sitting on a bike for an hour or more as a way to improve my aerobic base. Full disclosure, this does actually work, it’s just not the most efficient way to do it and as a frequent training method, I hated it and my body hated me for doing it.
If your goal is to run a road race then you absolutely should be running long distances to train your tissues to withstand the repetitive nature of a race or if you enjoy running for distance then great, do it. However, if your goal is to improve your general fitness, lose weight, train for a team sport or really anything other than training for an endurance race then interval training should be the bulk of your conditioning work. It’s important to understand what your goals are and your training methods should be chosen based off these goals.
Although it took me a long time to come around to interval training there is just too much research supporting it to argue now. The media has glorified long duration endurance training for a long time and many charity events are based around distance running, however, it’s clearly not the most efficient way to train. As interval training has come into the media the focus is often on HIIT but the intensity and duration of intervals should be reflective of the user and their goals. Dr. Gibala highlights a study in his book The One Minute Workout from Japan where they took out-of-shape people in their mid-fifties and had them vary their walking speed for about three minutes at a time which resulted in much larger improvements in fitness levels compared to steady walking. Another study from the University of Copenhagaen showed big improvements in fitness level and body composition in type-2 diabetics when using this protocol where steady state walking did not. Studies done previously used sedentary people in their 70s. This was all done by walking. Walking. It didn’t involve any of the fancy bootcamp style equipment that so many people think they need to use intervals. It didn’t involve hill sprints or any risky activity. Grandma and grandpa can use interval training.
Lets look at two methods I have written about before: Tempo intervals and High Resistance Intervals (HRI). They both involve short sprints but they require drastically different levels of effort. Tempo intervals, done by running down a field or cycling at 70-80% speed, last 10-15 seconds then you rest for a minute where HRI involves the same duration but you will sprint at near 100%, usually up a hill, dragging a sled or crank up the resistance on a bike**. Tempo intervals generally result in a post-interval heart rate of 140-150 BPM and most of the time it drops right down to 100-110 between and during HRI you’ll generally see a spike of about 160-170 BPM then it should drop back down to 130 between intervals. Tempo intervals were used by Charlie Francis with his sprinters to improve aerobic fitness without adding in a ton of mileage. Methods like these two are super beneficial to athletes because they allow for great things like full hip flexion and extension, competition-like speed and they limit the repetitive impact on the joints from long distance running (which is about 1300 steps per km). The other great thing about methods like this is the time commitment and the overall time spent actually working hard is far less than going out for 45-60 minutes of jogging. You are only spending 15-30 minutes total using these methods and actually only less than 8 minutes of actual work if you complete the higher dosage of 30 minutes of 15 second sprints.
All three methods, varied-speed walking, tempo sprints and HRI are quite appropriate for most populations, with HRI being the least for injured, elderly and severely out-of-shape people. None of these methods should ever leave you in a heap on the floor regardless of your fitness level. Interval training is as hard as it needs to be. It doesn’t have to destroy you or the back of your pants. The great part about these and other interval training methods is they are self-regulating. Interval training is best regulated by RPE: Rate of Perceived Exertion so if the interval calls for a 6 effort and a 6 effort that day is what a good day’s 4 would be, then that’s your 6 effort. RPE takes into account how you’re feeling that day, workout and interval. When you improve your fitness and a given pace starts to feel like a 5 instead of a 6 then you can just speed up and now you’re exercising at the appropriate level again. This doesn’t even require changing the method or time of the interval.
I will generally use these 3 methods heavily in general endurance phases and I will use them on recovery days during any strength phases to maintain my level of fitness during that month or two. If you are already pretty fit and wondering what kind of intervals to start with a simple way is to take your resting heart rate. If it is above 60 BPM then you could benefit from making this type of training the major player in your program for a while. If you’re below 60 then you can look into more intense methods with longer intervals (more anaerobic). When you move to tougher methods then you can take a look at your recovery heart rate. If you can’t get your heart rate down at least 30 beats within the first minute you probably need more aerobic work like tempo repeats.
Hopefully, this has provided some sort of starting point for you if you were on the fence. Don’t be like me and continue to waste your time with long duration cardio if you hate it, play team sports or are constantly developing overuse injuries. Train smarter, with intervals, no matter how old or fit you are.
Check out this article on 8-weeks out for more info about tempo training from Joel Jamieson. Even take a minute to check out some of the anecdotal evidence from people in the comments section.
**If training without a sled or hill you can do 5/10 yard shuttles for HRI. The constant acceleration and deceleration increases the feeling of resistance each sprint. It also works on important skills for injury prevention and performance enhancement. In the past, especially with teams and young athletes I have had them sprint 5 yards, backpedal 5 to the start then sprint 10 yards, turn and sprint the 10 yards back, then turn and finish off the 10 yards again. I always say to turn facing the same object so that they turn both right and left each interval. This usually takes 10-12 seconds and I’ll line them up 6-7 athletes deep then they get about 1-1.25 minutes of rest before going again without having to time it. I prefer this set up because I can coach up mechanics rather than stare at a stopwatch and say go/stop the whole time.