New Study: HIIT as effective as endurance training. Anti-oxidants interfere!

[ScioAgapeOmnis]

New study (peer reviewed) came out that shows evidence that HIIT (High Intensity Interval Training) produces the same benefits as prolonged endurance training.

Article:
http://www.thelatestnews.com/scientists-discovered-why-can-high-intensity-interval-training-match-endurance-training/

Link to entire study:
http://www.pdf-archive.com/2015/11/05/pnas-2015-place-1507176112/pnas-2015-place-1507176112.pdf

Relevant extracts:

High-intensity interval training (HIIT) is a time-efficient way of improving physical performance in healthy subjects and in patients with common chronic diseases, but less so in elite endurance athletes. The mechanisms underlying the effectiveness of HIIT are uncertain. Here, recreationally active human subjects performed highly de- manding HIIT consisting of 30-s bouts of all-out cycling with 4-min rest in between bouts (≤3 min total exercise time). Skeletal muscle biopsies taken 24 h after the HIIT exercise showed an extensive frag- mentation of the sarcoplasmic reticulum (SR) Ca2+ release channel, the ryanodine receptor type 1 (RyR1). The HIIT exercise also caused a prolonged force depression and triggered major changes in the expression of genes related to endurance exercise. Subsequent exper- iments on elite endurance athletes performing the same HIIT exercise showed no RyR1 fragmentation or prolonged changes in the expres- sion of endurance-related genes. Finally, mechanistic experiments performed on isolated mouse muscles exposed to HIIT-mimicking stimulation showed reactive oxygen/nitrogen species (ROS)-depen- dent RyR1 fragmentation, calpain activation, increased SR Ca2+ leak at rest, and depressed force production due to impaired SR Ca2+ re- lease upon stimulation. In conclusion, HIIT exercise induces a ROS- dependent RyR1 fragmentation in muscles of recreationally active subjects, and the resulting changes in muscle fiber Ca2+-handling trig- ger muscular adaptations. However, the same HIIT exercise does not cause RyR1 fragmentation in muscles of elite endurance athletes, which may explain why HIIT is less effective in this group.

...

Significance
High-intensity interval training (HIIT) has become popular be- cause it is a time-efficient way to increase endurance. An in- triguing and so-far-unanswered question is how a few minutes of HIIT can be that effective. We exposed recreationally active men to one session of three to six sets of 30-s high-intensity cycling exercise. Muscle biopsies taken 24 h later showed an extensive fragmentation of the sarcoplasmic reticulum (SR) Ca2+ channels, the ryanodine receptor 1 (RyR1). In isolated mouse muscle fibers, this fragmentation was accompanied by increased SR Ca2+ leak, which can trigger mitochondrial bio- genesis. The HIIT-induced RyR1 fragmentation did not occur in muscles exposed to antioxidant, which offers an explanation for why antioxidants blunt effects of endurance training.

So while the study confirmed what many already knew, that high intensity brief bouts of exercise can have the same positive effect as prolonged long intensity endurance training, the part about anti-oxidants interfering with the positive adaptations of your body to the stress induced by exercise caught my attention. Here's an article that talks more about this:

http://well.blogs.nytimes.com/2014/02/12/why-vitamins-may-be-bad-for-your-workout/?_r=0

Many people take vitamins as part of their daily fitness regimens, having heard that antioxidants aid physical recovery and amplify the impact of workouts. But in another example of science undercutting deeply held assumptions, several new experiments find that antioxidant supplements may actually reduce the benefits of training.

Antioxidants became popular dietary supplements largely because they were said to sop up free radicals, the highly reactive oxygen molecules that are generated during daily activities. Physical exertion, through its breakdown of oxygen, results in the creation of large numbers of these molecules, which, in excess, can lead to cell death and tissue damage. So it seems logical that reducing the number of free radicals produced by exercise would be desirable.

Enter antioxidants, which absorb and deactivate free radicals. While the body creates its own antioxidants, until recently many researchers believed that we produce too few natural antioxidants to counteract the depredations from free radicals created during exercise. So many people who exercise began downing large doses of antioxidants such as vitamins C and E, even though few experiments in people had actually examined the precise physiological impacts of antioxidant supplements in people who work out.

For a study published last week in The Journal of Physiology, researchers with the Norwegian School of Sport Sciences in Oslo and other institutions gathered 54 healthy adult men and women, most of them recreational runners or cyclists, and conducted a series of tests, including muscle biopsies, blood draws and treadmill runs, to establish their baseline endurance capacity and the cellular health of their muscles.

Then they divided the volunteers into two groups. Those in one group took four pills a day, delivering a total dose of 1,000 milligrams of vitamin C and 235 milligrams of vitamin E. Members of the second group got identical placebo pills.

Finally, they asked all of the participants to complete a vigorous 11-week training program, consisting of increasingly intense interval sessions once or twice per week, together with two weekly sessions of moderately paced hour-long runs. By the end, all of the volunteers were more fit than they had been at the start, with their maximum endurance capacity increasing by an average of about 8 percent.

But their bodies had responded quite differently to the training. The runners who had swallowed the placebo pills showed robust increases of biochemical markers that are known to goose the creation of mitochondria, the tiny structures within cells that generate energy, in cells in their bloodstream and muscles. More mitochondria, especially in muscle cells, means more energy and, by and large, better health and fitness. The creation of new mitochondria is, in fact, generally held to be one of the most important effects of exercise.

But the volunteers who had consumed the antioxidants had significantly lower levels of the markers related to mitochondrial creation. The researchers didn’t actually count the specific populations of mitochondria within their volunteers’ muscles cells, but presumably, over time, those taking the antioxidants would see a smaller uptick in mitochondrial density than among those not taking them.

That finding echoes the results of another study of antioxidant supplementation and exercise, also published last year in The Journal of Physiology, in which half of a group of older men downed 250 milligrams daily of the supplement resveratrol, an antioxidant famously found in red wine, and the other half took a placebo. After two months of exercising, the men taking the placebo showed significant and favorable changes in their blood pressure, cholesterol profiles and arteries, with fewer evident arterial plaques.

The men taking the resveratrol were not as fortunate. They had exercised as much as the other men, but their blood pressures, cholesterol levels and arteries had remained stubbornly almost unchanged.

Why and how antioxidant supplements would blunt the effects of exercise is not altogether clear, said Goran Paulsen, a researcher at the Norwegian School of Sport Sciences, who led the vitamin C and E study. But he and many other physiologists have begun to suspect that free radicals may play a different role during and after exercise than previously thought.

In this theory, free radicals are not villainous but serve as messengers, nudging genes and other bodily systems into starting the various biochemical reactions that end in stronger muscles and better metabolic health. Without free radicals, those reactions don’t begin.

And large doses of antioxidant supplements absorb most of the free radicals produced by exercise.

Of course, that theory is still unsubstantiated and requires long-term testing in people, Dr. Paulsen said. It is possible, he said, that smaller doses of antioxidants or different formulations might be useful for athletes. Meanwhile, natural antioxidants from food sources, such as blueberries and red wine, are unlikely to be problematic, he said. “It’s probably only concentrated extracts that are potentially dangerous,” he said. It is also worth pointing out that the volunteers who took the concentrated extracts of vitamins C and E increased their endurance to the same extent as those taking a placebo.

On the other hand, the supplements did not improve performance in comparison with a placebo, so why bother with them, Dr. Paulsen asked. “Personally, I would avoid high dosages” of antioxidants while training, he said. The science on the topic may not be complete, but the intimation of the recent studies is that by downing the supplements, “you risk losing some of the benefits of exercise.”

So while vitamin c is good to combat free radicals when we are feeling ill, it seems like the free radicals produced by exercise are good for us, forcing our body to adapt by growing mitochondria among other things, and perhaps in this instance trying to assist your body with anti-oxidants is akin to letting a butterfly out of its cocoon without letting it fight and get out on its own - dooming its adaptations in the process.

Thought this was interesting and wanted to share. Not sure if this would also be a good addition to the thread regarding mitochondrial DNA activation, but it sure seems to have relevance from what I understand.

 

[monotonic]

I think based on some rare science reports, we could have guessed early on that taking antioxidants when you are not actually sick might not be optimal. I couldn't find the forum thread for this article:

http://www.sciencedaily.com/releases/2010/12/101220084442.htm

Free radicals that are produced by the body are biological signals - they carry information and send messages. Antioxidants can interfere with those messages as this HIIT study shows.

 

[nicklebleu]

Thanks, SAO, for posting - fascinating stuff! I've been doing HIIT for quite a while AND. taking high-dose vit. C ...

 

[ScioAgapeOmnis]

No probs, and I think if you are eating a "well balanced diet", you really don't need supplements anyway. A well formulated keto diet - using organic grass fed meats, fish, eggs, avocados, and whatever else qualifies that you're not sensitive to should provide you with everything the body needs. If you want to cut down or stop vit c, it would be interesting what effect that would have on your HIIT benefits (assuming you're not taking it for some condition that needs it).

 

[nicklebleu]

No probs, and I think if you are eating a "well balanced diet", you really don't need supplements anyway. A well formulated keto diet - using organic grass fed meats, fish, eggs, avocados, and whatever else qualifies that you're not sensitive to should provide you with everything the body needs. If you want to cut down or stop vit c, it would be interesting what effect that would have on your HIIT benefits (assuming you're not taking it for some condition that needs it).

Exactly my thoughts as well - will definitely try that, although I recently replaced HIIT with Yoga, because the form of HIIT I was doing (sprints) exacerbated my back pain. Would like to try doing that on a spin bike, but don't currently have access to one.

 

[beetlemaniac]

I used to do HIIT on the stationary bike but recently have stopped it as it may have been affecting my sleep. I have to work out at night after work, at around 7 pm, but now that I think about it, I could do it on the weekends instead. It could have been the runaway stress response that caused the insomnia, so now I just do weight training and swimming for my routine exercise. My body can have unpredictable responses to stimuli, as I have found out. I used to be fine doing HIIT at night, earlier on. Found an article on it at here: _http://fitness.mercola.com/sites/fitness/archive/2015/01/02/post-workout-insomnia.aspx

The study on antioxidants is very interesting. Thanks.