HIIT it hard

It’s the most pop­u­lar trend in fit­ness – and the most misun­der­stood. Use the lat­est sci­ence to re­think your high-in­ten­sity train­ing and make big gains

Men's Fitness - - Contents - Words Joel Snape Pho­tog­ra­phy Glen Bur­rows

Fight fat more ef­fec­tively with high­in­ten­sity work­outs. Our fea­ture tells you all you need to know

It may have achieved un­prece­dented pop­u­lar­ity in the past few years but what­ever you’ve heard, high-in­ten­sity in­ter­val train­ing (HIIT) isn’t new. In 1912, Fin­nish ath­lete Hannes Kolehmainen used in­ter­val-style train­ing in his prepa­ra­tion for the Olympics, and came away with three golds in the 5,000m, 10,000m and cross-coun­try events. In 1952 Emil Zá­topek, one of the most cel­e­brated dis­tance ath­letes of all time, won the Olympic marathon on a regime that in­cluded 400m in­ter­val sprints. And in the 1970s, Se­bas­tian Coe’s father Peter used HIIT prin­ci­ples to cre­ate ses­sions of re­peated 200m sprints that shaped his son into one of Bri­tain’s best ever mid­dle dis­tance run­ners.

What’s changed since then is the sci­ence. You’ve prob­a­bly heard of the Ta­bata regime – eight sets of 20 sec­onds’ high-in­ten­sity work with ten sec­onds of rest, based on a 1996 study by Pro­fes­sor Izumi Ta­bata – but that re­search is just the tip of the ice­berg. In re­cent decades, there’s been a huge amount of re­search into ex­actly how dif­fer­ent work-rest in­ter­vals, lev­els of in­ten­sity, and move­ments af­fect the re­sults you get from HIIT.

And yet, when a lot of train­ers ex­plain it, the only de­scrip­tion given is “hard work, short rests”. In short, there’s a bet­ter way to do HIIT.


First, it’s im­por­tant to un­der­stand that while HIIT is an ef­fec­tive fat burner, it has a host of other ben­e­fits: up­ping your VO2 max (the amount of oxy­gen your body can use and an in­di­ca­tor of car­dio fit­ness), re­duc­ing lac­tate ac­cu­mu­la­tion (so you can train harder, for longer), and in­creas­ing en­zyme ac­tiv­ity to re­duce fa­tigue. When you start, al­most any for­mat will work, but as you get bet­ter adapted to the work­out method, tweak­ing your rou­tine will help you fo­cus on what you need to im­prove.

It starts with your body’s en­ergy path­ways. There are three: the ATP-PC, which fu­els high-power, short-lived ac­tiv­i­ties like ex­plo­sive weightlift­ing or sprints; the gly­colytic, which takes over for mod­er­at­e­du­ra­tion ac­tiv­i­ties; and the ox­ida­tive, which is in con­trol for any­thing be­yond that. The first two are anaer­o­bic, which means they don’t use oxy­gen, and the last is aer­o­bic be­cause it does. HIIT works both your aer­o­bic and anaer­o­bic sys­tems, but how it works the dif­fer­ent en­ergy path­ways de­pends on the work/rest ra­tios you’re us­ing.

In a 2001 study, for in­stance, re­searchers found that the aer­o­bic sys­tem’s con­tri­bu­tion to en­ergy rock­ets from 6% af­ter ten sec­onds of ex­er­cise to 45% af­ter 60 sec­onds. But the same hap­pens dur­ing re­peated sprints: in one Lough­bor­ough Uni­ver­sity study, the anaer­o­bic sys­tems pro­vided all of a test sub­ject’s en­ergy for the first of ten sixsec­ond sprints (with a 30-sec­ond rest), but by the end they were sup­ply­ing around 35%, with the rest com­ing from aer­o­bic fit­ness.

What does that mean? Well, it means that 30 sec­onds’ rest isn’t enough to im­prove power, but the main take­away should be that your work­out doesn’t have to leave you in a pool of sweat on the floor (depend­ing on your aim). A 2011 study pub­lished in the Jour­nal Of Strength And Con­di­tion­ing Re­search found that test sub­jects do­ing a “de­scend­ing” sprint pro­to­col, which was rated eas­ier than an “as­cend­ing” pro­to­col that used the same dis­tances, ex­pe­ri­enced a higher rise in growth hor­mone and testos­terone. Some­times, it’s not about how ex­hausted you feel.


If you’re feel­ing worn down in the first place, of course, HIIT isn’t the ses­sion to go for. “A com­mon mis­take with HIIT is the as­sump­tion that it trumps steady-state car­dio at all times, which isn’t true,” says trainer David Jor­dan (th­e­fit­tin­grooms.com). “HIIT is highly ef­fec­tive be­cause it re­quires less time and burns calo­ries dur­ing re­cov­ery. How­ever, to reap the ben­e­fits of HIIT you need to at­tack it with a lot of en­ergy. On days when you’re feel­ing less than 100% or, more im­por­tantly, you’re sore from your pre­vi­ous work­out and are at risk of pulling a mus­cle, then steady-state car­dio is prob­a­bly more ef­fec­tive – and safer.”

Fi­nally, it’s im­por­tant to con­sider how of­ten you can do “real” HIIT. “It’s true that HIIT can trig­ger pro­tein syn­the­sis but it also causes pro­tein break­down,” says Jor­dan. “Do­ing sev­eral HIIT ses­sions a week would be catabolic so while you’d lose weight over­all, some of that loss would be mus­cle mass. If build­ing mus­cle is a goal, proper weight train­ing still needs to be your pri­mary fo­cus with HIIT as a sup­ple­ment. A train­ing split of two weights ses­sions and two HIIT a ses­sions a week would keep you lean, while mak­ing sure you aren’t over­trained.”

Re­mem­ber: it’s sup­posed to be short, in­tense and in­fre­quent, not an ev­ery­day ef­fort. Read on to find out how to struc­ture your HIIT work­outs.

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