HIIT Demystified!

Why do we always look for the easy way out? Getting in shape and improving athletic performance takes work – you sweat, you burn, you repeat. Training methods continue to evolve but they all have a common thread, hard work.

Zealots of high intensity interval training or HIIT for short, profess that short and intense bursts of exercise are all one needs to get in shape. That’s right, it’s a dream come true – work out less yet gain more – but only if you’re looking for a way to hit the bare minimum.

It’s true that gains from HIIT rival those of longer workouts but only when compared to low intensity, steady state training. That’s basically the kind of intensity seen on elliptical trainers all over the country – if you can read a magazine while exercising, it shouldn’t come as any surprise that it doesn’t provide maximal benefit.

High intensity interval training has gained favor as a way to get a quick efficient workout. The theory of HIIT, supported by reams of scientific articles, is that multiple, hard as you can intervals can equal the benefit of a slower (read – easier) but much longer exercise sessions.

The classic session – called Tabatas after the researcher that developed the program – involves 4 minutes of alternating 20-second maximum efforts with brief 10-second rest periods. A training program built around two of those four-minute efforts was found to supply equal benefits as 40 minutes of easier exercise. Eight minutes of hard exercise versus 40 minutes – most would make that choice.

But slow down – literally and figuratively – exclusively jumping on the HIIT bandwagon ignores the fact that the body uses a variety of systems to power exercise. While the systems overlap, focusing exclusively on one type of training ignores other important energy systems that are responsible for peak performance. Even the coaches and researchers that recommend HIIT specify that it shouldn’t comprise more than 20% of a training program.

While HIIT training has become the workout du jour, threshold steady-state training (sustained hard effort) has been used for years by top coaches and athletes as it improves the body’s ability to eliminate lactic acid.

Steady state workouts are performed at the highest intensity that one can sustain for a 20-60 minutes, i.e. race pace. Although HIIT is performed at a higher absolute intensity, it incorporates frequent breaks that allow the participant to recover. Steady state or lactate threshold training is performed at a high intensity for a much longer time, allowing the body to adapt physiologically to sustained hard efforts. To use a running example – improving your lactate threshold allows one to run a 5k at a 7:00 min/mile pace rather than a 7:30 pace.

There are multiple pillars that form the foundation of athletic performance and they include – strength, cardiovascular endurance, power, and speed. While the relative balance may differ by sport or activity, all of these facets should be addressed to achieve full athletic potential. For example, a football player doesn’t need the same type of aerobic endurance that a marathoner might, but still needs the endurance necessary to sustain repeated hard efforts over the course of a game.

Conversely, the marathoner doesn’t need to be able to push around 300-lb defensive linemen but needs the strength to shock absorb joints and maximize muscular endurance and efficiency. Weak muscles have to apply too much energy per stride and so quickly become fatigued and inefficient.

One study of different training methods in rowers found that steady state threshold training elicited the greatest response in muscle building hormones. Sustained exercise, as compared to interval type training, increased testosterone and growth hormone levels to a greater extent. Increases in growth hormones are critical not only for improvements in fitness and performance but have been linked to improved mental function and well-being.

When it comes to weight loss a recent article in the Journal of Obesity found that while HIIT may be advocated as a time-efficient strategy for eliciting comparable fitness benefits as traditional continuous exercise it appears to be less effective for weight loss.

This by no means suggests that high intensity interval training is a waste of time or isn’t a valuable tool in improving fitness. The take-away points should be: exercise training should incorporate a variety of different intensities and times to provide maximum benefit; and the most important, there are no shortcuts in health and fitness.