Saturday, March 26, 2016

How Much HIIT Is Beneficial?

Picture by Irving Henson from The PIT
A young lady I spoke to in the clinic today told me she has been attending HIIT (or high intensity interval training) sessions recently and gotten injured. (HIIT involves alternating very intense bouts of exercise with low intensity recovery exercise. It can be done in the gym with weights or on the bike or running set times or distances).

Being on the slightly plump side, she was tempted by the many benefits promised by the trainer conducting the HIIT sessions and the fact that she could lose weight and become stronger quickly whilst spending little time training.

Sounds too good to be true?

Considerable evidence definitely exists to support a role for low volume HIIT as a potent and super time efficient training method for inducing both central (cardiovascular) and peripheral (skeletal muscle) adaptations that are linked to improved health outcomes (see references below).

HIIT is designed to briefly strain your body to its limits. And these short bursts of very intense exercise lead to beneficial physiological changes similar to those much longer duration workouts. How much or how little do you need is still debated.

Leading interval training researcher Professor Martin Gibala found that 30 seconds worth of sprint intervals (four to six repeats of all out efforts three times a week) in young active but trained males produced just as good results as endurance training (subjects rode continuously for 40-60 mins five times a week). This is also known as the Wingate Test. The subjects generally hated the process though.

I clearly remember doing this while I was a young physiotherapy student in our Exercise Physiology lessons. It's extremely demanding and may not be safe, tolerable or appealing for some individuals. Definitely not for the faint-hearted.

With a less taxing program in which subjects did 60 seconds interval (or HIIT) training at 90 % effort (10 reps), the subjects found it more bearable although they had to do more repetitions (10x) to get the same benefits as the 30 seconds all out effort (Gibala et al, 2012).

Here's another workout that may be more palatable. Dr Gibala studied a group of obese/ overweight group of men and women on a program of 20 seconds of all out intervals followed by a recovery of two minutes.

They started with a 2 minute warm up on a stationary bike, followed by 3 x 20 seconds of all out sprints with two minutes recovery followed by a three minute cool down. A grand total of three minutes of intense work per week within a total training time of 30 minutes. Results were very encouraging as he subjects become fitter and improved their health (their VO2 max increased by 12%).

And if you find even 20 seconds of all out effort too difficult, there's the 30-20-10 workout which "only" requires 10 seconds of sprinting.

My take? Clearly, despite its many benefits, HIIT is not suitable for everyone, especially if you're just starting on an exercise program. As I've written before, we live in an instantaneous society now where we want results at the snap of a finger. Train don't strain is still important, or you risk a visit to your physiotherapist or doctor soon.


Burgomaster KA, Howarth KR et al (2008). Similar Metabolic Adaptations During Exercise After Low Volume Sprint Interval And Traditional Endurance Training in Humans. J Physiol. 586(1): 151-160.

Gibala MJ, Little JP et al (2012). Physiological adaptations To Low-volume, High-intensity Interval Training In Health And Disease. J Physiol. 590(5): 1077-1084. DOI: 10.1113/physiol.2011.224725

Gillen JB, Percival ME et al (2014). Three Minutes of All-out Intermittent Exercise Per Week Increases Skeletal Muscle Oxidative Capacity And Improves Cardiometabolic Health. PlosONe. DOI: 10.1371/journal.pone.0111489.

Sunday, March 20, 2016

Not All Sitting Is Bad

He rarely sits like this .... always running around
Remember I wrote about active couch potatoes? And you've also read that sitting can negate some of the benefits of your exercise. Or worse still, some have said that sitting is the new smoking.

Well fret not, it seems that some sitting is not quite as bad as it seems.

Published research seems to suggest that not all sitting is the same. Well, at least sitting on your sofa and watching television is different from sitting at your desk at work.

Researchers studied over 3000 subjects who completed a series of surveys and had the thickness of their carotid artery walls measured with ultrasound (this is a good measure of heart disease risk).

The surveys measured television viewing time (in increments of two hours a day) and sedentary time at work (never, seldom, sometimes, often and always). Levels of physical activity were also measured.

The results showed that the more television the subjects watched, the thicker their artery walls, regardless of how much they exercised.

Surprise surprise, it was different however for workplace sitting. Those who sat more at work seemed to have better arteries, even after factoring in income levels and level of education.

This suggests that the nature of your sitting matters. The researchers mentioned that television watching is often completely uninterrupted and may be directly after high calorie meals like dinner. I guess I'm guilty of this sometimes and what's more, I am snacking while watching TV as well.

Workplace sitting may require the subjects to get up periodically to go to the printer, look for a colleague or going to the pantry etc.

The researchers also suggested potential confounding factors. Those who sat more at work were younger and likely to be employed full time while those who watched more TV seemed to be older, less educated or made less money. Results were adjusted to account for those differences.

I felt that there were some imitations in the study. The study may be more accurate if activity trackers were used instead of using surveys/ questionnaires to measure sedentary time.

Short breaks (from your sedentary sitting) seems to be critical in making a big difference. So whether you work from home or in an office, or work alone or in a group, meet your clients of spend time on the phone, make sure you get up and move every so often.

And if you've been sitting there too long reading this, you know you gotta move.


Diaz KM, Booth JN III et al (2016). Sedentary behaviour And Subclinical Atherosclerosis in African Americans: Cross-sectional Analysis Of The Jackson Heart Study. Int J Behav Nutr Phys Act. DOI: 10.1186/s12966-016-0349-y.

Sunday, March 13, 2016

Don't Make Excuses When You Get Dropped

Me (left) at the 2005 SEA games triathlon event
I used to race. I started when I was 12 years old with cross country races, track events, road races and later triathlon.

I still get asked by both my friends and patients if I still race. Well, for those of you wondering, not anymore. I stopped training seriously since March 2008 and am definitely in no condition to race.

I still ride my bike though even after my accident. While out riding recently, I overheard a guy telling his friend next to him why he was having a lousy ride.

That made me remember this guy who was a good athlete. We used to ride and train together sometimes. There would be times when I'd be suffering and stay in the back of the group and of course there were days when I was up the hills quickest too. This person will say "Nice climb" or "Man, you killed us on that hill!" But straight after he said those things, he would follow them up with an excuse for why he'd been dropped or was having a poor run/ ride.

It was always like that. His compliments came with an excuse for why he lost and/ or was dropped. He made it sound like the only reason he did not do well was because of sleep/ food/ muscle issues/ work issues/ family problems etc. After hearing what he said, I sometimes wondered if I was having a good training day or it was him having a particularly bad one.

Looking back, I thought it was a terrible way to make the rest of the group feel. Granted, there will be days when someone we are running or cycling with feel great and do amazing things and kick our butts. And I feel that when that happens all credit and compliments should be given with no excuses attached.

I was reminded of that yesterday when I was behind on a climb at the end of our ride. I couldn't keep up near the crest of the hill and lost ground with each pedal stroke.

I thought about it and remembered what that guy would say. And I when caught up with the person who dropped me I told him "You were great!"

Sunday, March 6, 2016

Don't Start Too Fast In Your Race

Picture by richseow from Flickr

I've written about why why you shouldn't start too fast in your race before. Well. here's the science behind it.

Researchers studied a group of world class orienteers and skiers whose average VO2 max read 80.7ml/kg/min. Now that is truly world class.

The subjects were first made to run hard to tire them out. They were allowed to recover for a few minutes until their lactate levels reach either 3 or 5 mol/L. Thereafter, their running economy was measure while they ran at their threshold pace (or before they start to accumulate lactic acid, usually at 4 mol/L).

The results showed that when they were less recovered (5mmol/L of lactate, their running economy (or how much oxygen and energy required to cover a certain distance) was 5.5 percent worse. This is a huge difference. The authors suggest this would translate to 30 seconds for a 10 minute run, three minutes in an one hour run or 8:25 minutes in a full marathon.

The authors suggest that this should caution anyone starting too fast in a race as too fast a start causes an accumulation of lactate and you'll not be running as efficiently for the latter stages of the race.

Bear in mind that the subjects in the study were tested in laboratory conditions (i.e ideal).

In hot, super humid and sunny Singapore, your running economy definitely worsens after an hour of running. Two hours or more of running? You betcha. If you didn't read how I started too fast (and lost) in my first serious 800m race, read this.


Hoff J. Storen O et al (2016). Increased Blood Lactate Level Deteriorates Running Economy In World Class Endurance Athletes. J Strength Cond Res. DOI: 10.1519/JSC.0000000000001349.