Sunday, June 24, 2012

A couple more studies on HIIT

These two came out last week and I thought I'd pop them up here for your interest.  Incidentally I suspect that most of the benefits of HIIT could be attained more quickly and with less risk, through proper resistance training.....but that is a different issue.

Anyway, the studies:

Twelve weeks of HIIE resulted in significant reductions in total, abdominal, trunk, and visceral fat and significant increases in fat free mass and aerobic power.

The actual protocol was quite tough by the look of it:

Subjects in the exercise group completed supervised exercise (8 s sprint, 12 s recovery) continuously throughout each 20-min session. The HIIE workload was set at 80–90% of each subject’s heart rate (HR) peak at a cadence between 120 and 130 r.p.m and recovery was set at the same amount of resistance but at a cadence of 40 r.p.m. Subjects were instructed to keep their exercise intensity at a level necessary to produce a HR between 80–90% of HR peak. As subjects adapted to HIIE training, workload was increased so HR stayed at the appropriate 80–90% HR peak level. HIIE was coordinated with a prerecorded compact disc counting down each sprint in a 3-2-1 manner. Subjects performed a 5-min warm-up and cool-down on the bike prior to and after each exercise session. All training cycling data included continuous recording of HR and r.p.m, whereas rating of perceived exertion [13] (RPE) was assessed at 5-min intervals. 

High-intensity interval training and hypertension: maximizing the benefits of exercise?

Essential arterial hypertension is the most common risk factor for cardiovascular morbidity and mortality. Regular exercise is a well-established intervention for the prevention and treatment of hypertension. Continuous moderate-intensity exercise training (CMT) that can be sustained for 30 min or more has been traditionally recommended for hypertension prevention and treatment. On the other hand, several studies have shown that high-intensity interval training (HIT), which consists of several bouts of high-intensity exercise (~85% to 95% of HR(MAX) and/or VO(2MAX) lasting 1 to 4 min interspersed with intervals of rest or active recovery, is superior to CMT for improving cardiorespiratory fitness, endothelial function and its markers, insulin sensitivity, markers of sympathetic activity and arterial stiffness in hypertensive and normotensive at high familial risk for hypertension subjects. This compelling evidence suggesting larger beneficial effects of HIT for several factors involved in the pathophysiology of hypertension raises the hypothesis that HIT may be more effective for preventing and controlling hypertension. 


Anonymous said...

Hi Chris -
I've always wondered how the times used in these interval studies (like this one and Tabata's original work) should be translated when one is using a different mode of exercise, e.g. running, rowing, etc. Ant thoughts?

Also, while the 20 minute duration may seem pretty tough when one is thinking of the Tabata protocol (I don't think it's possible to keep up the prescribed pace doing 20s:10S Tabatas), when the work duration is sufficiently short (less than 10-12 seconds if I recall correctly) such that oxygen bound to myoglobin isn't depleted, the intensity can be kept up for much longer before one feels gassed. Now, it's been my experience when using these "ultra short high intensity interval" protocols that you feel it more in the muscles being worked than in the lungs. There were a few papers on this type of protocol a few years ago. I'll see if I can find them, but if you google "ultra short high intensity inter van training" you should find it.

Anonymous said...

Sorry, flip flop the remark I made about your lungs feeling fresh, but your legs feeling like jelly. I hadn't done one of these ultra-short deals in a few years. So, I went out and did 8 sec work: 12 sec rest with a Prowler loaded w/ 90 pounds. Legs felt great(unlike with tabata type protocol), but lungs felt like they were ready to explode!

Khaled Allen said...

I am curious what you mean about most of the benefits being gained in less time with resistance training. I would agree but am curious about the mechanism. My girlfriend has been training in starting strength protocol and can now run consistently far and fast for the first time in her life, so clearly weight training does improve heart and lungs.

Ondrej said...

1) For bigger muscles, you need adequate supply from cardiopulmonal system. When you run, you train muscles less effectively...HIT strength training is in fact designed to give the muscle the largest realistically possible and desired stimulus to adapt.
2) Strength training is much safer, no rapid, uncontrolled movement...

Anonymous said...

RE: "When you run, you train muscles less effectively.."

What do you mean by running. Are you talking about short sprints or long, slow distance training?

Also, "less effectively" for what? Certainly training muscles to be effective as a sprinter, sprinting is not an ineffective protocol.

As far as the blanket statement that strength training is safer than running, I guess you don't incorporate Olympic lifts into your program. Quite sad.

Ondrej said...

I meant it all (effective) for muscular hypertrophy, the driving force behind cardiopulmonal adaptation. I believe most of adaptations for running occur at the level of learning skill and body composition changes that allow better results during some measures in lab on a treadmill for example. But that's my opinion.

Jason Keck said...

The book Body by Science, by Doug McGuff, gives an amazing explanation for why HIIT is superior to CMT. From what I understand, unlike CMT, HIIT stimulates all the metabolic pathways of the body which provides a variety of benefits. I think the public will catch on and "aerobics" will become a thing of the past.

Chris said...

With respect to the ways in which resistance training can enhance cardiovascular fitness, I'd point people to the review that I highlighted above:

brianA said...

Just be aware that there are risks associated with HIIT training. I'm currently on crutches with an achilles tendonitus problem that is due specifically to a HIIT session. I was warmed up well but I definitely was pushing hard. Granted, I'm 45 years old and I did this running on a track rather than cycling, etc.. I wonder if anyone has addressed the issue of injuries due to HIIT training?

FeelGoodEating said...

Congratulations!!!!! What a piece you put together here. WOW.

And from a personal perspective...
I know it to be true.
I ran a half marathon having never "trained" for it, except for my regular HIT workouts.
I did it without being winded and a respectable time of two hours.

Again congrats!