HIIT stands for High Intensity Interval Training which means spiking your heart rate and then having a short period of rest (or just a lower intensity move) where your heart rate can drop and recover. Then, of course, doing it over and over again.
Though there is no universal HIIT session duration, these intense workouts typically last under 30 minutes ( though they don’t have to 🙂 ). Length of high intensity intervals, rest periods and workout duration all vary based on fitness level and length of event you are training for.
For example if you were a volleyball player using a HIIT workout for overall strength and as a means to increase time to fatigue on the court, your intervals would be short and sweet such as the classic ‘tabata scheme.’ Volleyball points are quick bursts of energy with plenty of time to recover therefore in volleyball you’ll need to be able to go all out for about 20 seconds or so and then recover fully before the next point. You need LONG intervals if your sport is LONG.
On the other hand if you are using high intensity intervals for an olympic distance triathlon (1k swim, 40k bike and 10k run) and in particular you are training your run that day, you’ll need MUCH longer high intensity intervals and longer than 10 seconds to recover. One of my favorite timed interval sets for running is a ‘ladder set.’ So in general the fittest cardiovascular athletes can recover from their max heart rate in about 2 minutes so i use this as a means to slowly mold myself into just that! warm up 10 minute jog, 2 minutes hard/2 minutes easy, 4 minutes hard/2 minutes easy, 6 minutes hard/2 minutes easy…then back down the ladder – 6 minutes hard/2 minutes easy, 4 minutes hard/2 minutes easy, 2 minutes hard/2 minutes easy… and then a 10 minute cooldown jog (optionally barefoot).
The key marker of cardiovascular fitness is your heart rate variability, and how quickly your heart rate can drop to normal after getting close to your max heart rate.
The best example of this in the world is the sport of Biathlon: cross country skiing which spikes your heart rate and then shooting which demands a low heart rate to steady your hands and focus. This can also be seen in basketball and any sport that requires high intensity efforts such as sprints with finesse skills such as shooting.
IF YOU ARE NOT TRAINING FOR A SPORT:
For general fitness i suggest that you start off with something like tabata which is 20 seconds of work all out followed by 10 seconds of rest for 8 rounds. The total work time is only 4 minutes and it has great cardiovascular increases in just that short of a duration. You can use different exercises or the same exercise for each work interval.
Example 1: 8 rounds of: 20 seconds fast squats/10 seconds rest
Example 2: 2 rounds of: 20 sec fast squats/10 sec rest; 20 seconds of jumping jacks/10 seconds rest; 20 seconds fast back lunges/10 seconds rest; 20 seconds of mountain climbers/10 seconds rest
An example of a multi-tabata workout is like the one that i did in crossfitFBG in Fredericksburg last Friday:
8 rounds of: 20 seconds of max sit ups/10 sec rest
8 rounds of: 20 seconds sprint on the bike/10 seconds rest
8 rounds of: 20 sec kettlebell swings/10 sec rest
8 rounds of: 20 sec double unders(jump rope)/10 seconds rest
as you get fitter you can increase the intensity of your workouts by:
- going harder during your interval: do more reps and increase your heart rate higher in the interval
- increasing the intensity of the move itself: jump squats versus squats, plyolunges vs lunges
- lengthening out the duration of the high intensity interval without sacrificing intensity
- shortening the rest interval
- exchanging the rest interval for a lower intensity move (no rest)