High-intensity interval training (HIIT) is one of the best ways to improve your fitness level. It’s a very efficient way to train because HIIT minimizes downtime and maximizes benefits. A few minutes of exercise performed correctly, goes a long way.
The concept is to work in your target heart rate zone’s upper ranges during the work intervals. And then maximize recovery benefits from the increased workloads between bouts.
Intensity is the operative word.
High Intensity Interval Training is an intense workout arranged as short bursts of backbreaking work. To qualify as a proper HIIT, you’ll need to push yourself to near maximum efforts during each rep and set along the way. Even recovery between each is purposeful.
That’s why repetitions are short, anywhere from 20 to 90 seconds. It’s the opposite of long slow distance where energy output is rationed to sustain the exercise for longer.
What distinguishes HIIT (or Sprint Interval Training) from the steady-state, continuous straining at an even pace are the intervals, those periods of heart-pounding intensity. To try it, you can take any sustained full-body movement, like running, cycling, or swimming, and create a pattern of work and rest that involves higher-speed and higher-incline bursts.
Early evidence suggests that high-intensity interval running might be more enjoyable than moderate-intensity continuous exercise (Bartlett et al., 2011 Jung et al. 2014 ), although everyday experience suggests that higher intensity exercise is inherently less comfortable (i.e. enjoyable).
Carl Foster, et al
The intensity level takes a little adjustment. To simultaneously help challenge and pace yourself, try cataloging your rate of perceived exertion (RPE) on an effort level of 1 to 10. That way, you can manage efforts without passing out from exhaustion during recovery and focus more on feeling the work at or near-maximum heart rate.
Short bursts
High-intensity interval training (HIIT) involves short bursts of intensive exercise alternated with recovery periods. These short, repeated bursts have shown substantial health, fitness, and performance gains.
High-intensity interval training is performed at a submaximal level, around 80-95% of aerobic capacity. Hovering somewhere around the lactate threshold.
Sprint interval training (SIT) is a variety of high-intensity interval training that pushes beyond into VO2 peak and well past the onset of blood lactate accumulation or an exertion level of 10.
Here are a few opportunities to implement or change up your approach to HIIT:
- Treadmill sprints
- Stairmaster
- Spin Class
- Wind sprints on a soccer field
- Swimming
Whyte et al. [ 45 ] carried out a 2-week HIIE intervention and found that previously untrained males increased their anaerobic capacity by 8%, whereas Burgomaster et al. [ 32 ] found that Wingate test performance was increased by 5.4% after two weeks of HIIE.
Stephen H. Boutcher
While in recovery from a repetition, VO is elevated (excess post oxygen consumption) to restore metabolic processes to baselines.
However, aerobic exercise protocols resulting in prolonged EPOC have shown that the EPOC comprises only 6–15% of the net total exercise oxygen cost.
Laforgia et al
Moreover, two minutes of HIIT done as top-end sprints (SIT) boosted metabolism over a day as much as 30 minutes of moderate-intensity. Due to the increased workout intensity, HIIT elevates metabolism for hours after the exercise session is complete. Meaning additional calories are burned well after you are done working out.
Appropriate rest intervals
Rest intervals between each set are a crucial part of the workout. If you don’t take time to recover, you’re not allowing peak oxygen consumption and lactate levels. If you take too much time, neither gets challenged enough to elicit adaptations.
An excellent place to start for beginners or if implementing into a periodized cycle for athletic performance is:
- 1:(between 2 and 6) ratio (work:rest). The shorter the burst, the more rest.
- As you improve, you can phase into a 1:1 ratio.
If challenging performance (examples below), all levels are appropriate, even a 1:2 ratio. But stagger them to accommodate race strategy.
Studies have shown that in such efforts, “Heart rate increased to 142 bpm after the first sprint and then increased to 173 bpm following sprint ten.”
In essence, short term responses to a session of HIIT are:
significant increases in heart rate, catecholamines, cortisol, growth hormone, plasma lactate and glucose levels, glycerol, and a significant decrease in parasympathetic reactivation after HIIT, and depletion of ATP, PCr, and glycogen stores.
Stephen H. Boutcher
An overall session is about 20-45 minutes in length. And a popular derivative workout for challenging lactate accumulation is Tabata training (1:2 work to rest ratio). But pay close attention to muscle soreness and RPE for the next 24-48 hours to avoid overtraining.
Adequate recovery days
Suppose a single session of HIIT exercise sessions generally consists of a dynamic warm up period followed by repetitions of high-intensity exercises separated by foam rolling for active recovery. Like weightlifting, interval training must be allotted sufficient recovery time for muscles to repair and adapt.
In that case, similar to a single session, your weekly program should be comparable. Keep a pattern for 4-6 weeks to judge recovery needs, then challenge them over a 12-15 week period for best fitness and performance results.
High-intensity interval training (HIT), in a variety of forms, is today one of the most effective means of improving cardiorespiratory and metabolic function and, in turn, the physical performance of athletes. Prescription for HIT consists of the manipulation of up to nine variables, which include the work interval intensity and duration, relief interval intensity and duration, exercise modality, number of repetitions, number of series, as well as the between-series recovery duration and intensity.
Martin Buchheit, Paul B Laursen
In other words, when you’re not racing or playing big matches on the weekends, you can try up to three HIIT workouts a week, provided you allow ample recovery. Ideally, a day or two of more manageable practices between bouts to let your body bounce back from the physical stressors of HIIT.
Creates amazing fitness
HIIT is a fantastic workout, but it certainly isn’t the only type of training you should be doing.
And in fact, too much of a good thing is quite the opposite. Overtraining prevents you from working at your actual maximum aerobic and anaerobic capacities during subsequent sessions. Don’t periodize a HIIT session every day of the week. A more systemic approach? Three times per week with 24-48 hours of active recovery masked as any aerobic exercise below the lactate threshold.
And HIIT isn’t for everyone. If you’re training with a specific fitness goal in mind or a race strategy to execute, you’ll need to follow a periodized training program to maximize gains.
Perhaps, in our quest to find the ‘perfect exercise’ we have missed the more important issue of how to make exercise enjoyable enough to be continued long term.
Carl Foster et al
Pressed for time and still need an effective workout? Consider high-intensity interval training. HIIT is an efficient and time-effective alternative to lengthy workouts. When it comes to heart rate, it performs equal to or greater than doing a steady run for a longer time. The intensity is up, but the time commitment is down. You have to push yourself during every minute of it.
