Monday, August 31, 2015

Latest Research On The ITB (Iliotibial Band)

Picture taken with my Canon Ixus 
Mention the ITB (or iliotibial band) and images of pain quickly crop up. IT band syndrome is a painful overuse injury usually at the lateral (or outer) portion of the knee in many runners and cyclists.

Latest research on the IT band from Daniel Lieberman's Harvard lab by his former student Carolyn Eng shows that the IT band may not function as what was formerly believed.
Another view
The ITB runs along the outer part of the thigh, originating from your Tensor Fascia Lata and Gluteus Maximus muscles just above your hip to attach just below the knee. It is made up of fascia, an elastic connective tissue found throughout our body. Fascia is a sheath of connective tissue that wraps our muscle, nerves and blood vessels. It also connects our muscles to bones.

The researchers used human cadavers to investigate how the IT band moves and stretches during walking and running. A computer model was then built to calculate the forces and strains involved and then compared to the equivalent structure in chimpanzees (published in another journal).

Previously, the IT band's primary function was believed to stabilize the hip during walking. Carolyn Eng's research suggested that the IT band actually acts like a spring, storing energy when you swing your leg back and releasing it as the leg swings forward.

This energy storage capacity is highly developed in humans, enabling it to store 15 to 20 times more energy than a comparable structure in chimpanzees.

Lieberman suggested that if we consider evolution and how humans are adapted not just for walking but running as well, then the IT band is looked at at a totally different perspective. The IT band looked like another elastic structure, similar to the Achilles tendon, and this may be important for saving energy during walking and especially running.

The researchers estimate the IT band stores about seven joules of energy during fast running compared to about the standard estimate of about 50 joules in the Achilles tendon.

The researchers hope that with this improved standing of how the IT band works, they can compare how much forces the IT band transmits in runners with and without IT band pain. This will then establish a scientific basis for treating IT band injuries.


Eng CM, Arnold AS, Liberman DE et al (2015). The Capacity Of The Human Iliotibal Band To Store Elastic Energy During Running. J Biomech. pii: S0021-9290 (15) 00354-1. DOI:10.1016/j.jbiomech.2015.06.017.

Eng CM, Arnold AS et al (2015). The Human Iliotibila Band Is Specialized For Elastic Energy Storage Compared With The Chimp Fascia Lata. J Exp Biol. 218(15): 2382-2393. DOI: 10.1242/jeb.117952.

Here's Carolyn Eng's (Harvard University) computer simulation of a human leg running from here.

Wednesday, August 26, 2015

Bike Intervals Can Help You Run Faster

Our training machines
Looks like you gotta spend some time riding furiously on your (stationary) bike if you wanna run faster. All you need is 15 minutes to spare.

A recent study showed that with the right kind of high intensity training on a stationary bike, you can run faster.

The researchers tested runners on a treadmill with a 3 km time trial and split them into four groups. Three groups trained on a stationary bike for two weeks in addition to their regular running routine while a control group just maintained their regular running routine.

The runners did six interval sessions on the stationary bikes in all. Each runner completed six 10-seconds all out efforts. Each group varied the amount of rest between intervals. Rest ranged between 30 seconds to 80 seconds to two minutes rest for the runners. Including warm up and cool down, the session took less than fifteen minutes.

The results showed that the group with the shortest period of rest had the best results. The 30 seconds rest group ran about three percent (or about 25 seconds) faster!

Both the 80 seconds and two minute rest groups did not have any significant improvement in the 3 km time trial. There was no change in the control group.

The researchers attributed the improvement in performance to the elevated heart rate in the 30 second rest group. The short rest prevented the runners from recovering fully making each successive interval more difficult. Their muscles had to adapt faster to the increased load which helped them run faster in the subsequent time trial.

The authors recommend this workout as cross training to avoid injuries. Since stationary cycling also reduced training volume, it is a time efficient way of training as well. Runners who are injured can use this to maintain their fitness while recuperating.

When the weather does not permit you to run outside, you can still ride.


Kavaliauskas M et al (2015). High-intensity Cycling Training: The Effect Of Work-to-rest Intervals On Running Performance Measures. J Str Cond Research. 29(8): 2229-2236. DOI: 10.1519/JSC.0000000000000868.

Pedaling furiously while it was raining outside
My wife pedaling furiously 5 weeks after giving birth

Sunday, August 16, 2015

Running And Cancer

Picture by Eric Norris from Flickr
The common cold and flu are not the only illnesses that running can ward off. A running (or exercise) strengthened immune system can reduce the likelihood of a variety of illnesses, including many types of cancer.

A large Swedish study found that men who walked or cycled for at least 30 minutes a day had a 34 percent lower risk of dying of cancer compared to couch potatoes.

Researchers studying studying prostate cancer tumour growth in rats that exercise or were sedentary found that rats (like humans) divert blood flow to muscles when exercising. The researchers found a 200 percent increase in tumour blood flow during exercise.

When a tumour is flooded with oxygen, it's activity tends to slow (Jones et al, 2010). This actually leads to a rate of decelerated metastasis (spread of disease to other organs)

Another study by a different group of researchers showed that aerobic exercise leads to tissue returning to it's pre tumour state or ward off development of a more aggressive and dangerous cancer.

Greater blood flow and oxygen delivery to a tumour can possibly transport cancer fighting therapy to the tumour. Exercise increases blood flow by increasing blood pressure and pumping and by decreasing blood vessel constriction.

Exercise is also believed to help reduce cancer by other mechanisms. High insulin levels are associated with increased risk of cancer, and exercise helps reduce insulin levels. There are definitely other mechanisms by which exercise combats cancer that have not been discovered.

You don't have to wait to know these mechanisms to be discovered to get the cancer suppressing benefits of being a runner.


McCullough DJ, Nguyen LM et al (2013). Effects Of Exercise Training On Tumor Hypoxia And Vascular Function In The Rodent Preclinical Orthotopic Prostate Cancer Model. J Appl Physiol (1985). 115(12): 1846-54. DOI: 10.1152/japplphysiol.00949.2013.

McCullough DJ, Stabley JN et al (2014). Modulation Of Blood Flow, Hypoxia, And Vascular Function In Orthotopic Prostate Tumours During Exercise. J Natl Cancer Inst. 106(4): dju036. DOI: 10.1093/jnci/djuo36.

Orsini N, Mantzoros CS et al (2008). Association Of Physical Activity With Cancer Incidence, Mortality, And Survival: A Population-based Study Of Men. Br J Cancer. 98: 1864-1869. DOI: 10.1038/sj.bjc.6604354.

Jones LW, Viglianti BL et al (2010). Effect Of Aerobic Exercise On Tumor Physiology In An Animal Model Of Breast Cancer. J Appl Physiol (1985). 108(2): 343-348. DOI: 10.1152/japplphysiol.00424.2009.

Monday, August 10, 2015

Sports Drinks Cannot Replace Your Sodium Levels During Exercise

Gatorade- thirst quencher, but can it replace your sodium levels?
Last week I wrote about what causes muscle cramps. I also said I will write about why the Sports drink/ fluid replacement companies are inaccurate in telling us that sports drinks like Gatorade, Powerade and Endurox etc can replace electrolyte losses.

When you sweat, your electrolyte levels begin to rise! Yes, you read correctly. Let me explain more.

Let's say you have five cups of water and five teaspoons of salt in your system. If you remove one cup of water and a teaspoon of salt, the balance remains the same. There is a teaspoon of salt for every cup of water (i.e. a concentration of 1.0).

Now if you lose 2 cups of water (like when you exercise) and a teaspoon of salt, you've lost more water than salt. The concentration of salt has now risen to 1.25. Your salt (and electrolyte) levels are now higher and will remain higher as you become more dehydrated.

Apply this concept to our physiology. Our sodium (salt) concentration of blood is about 140 mM (or 3.2 grams of salt in every litre of blood). Our sweat has a sodium concentration between 20-50 mM. So even for "salty sweaters" (people who lose more salt than others when they sweat), they lose about 1.1 grams of salt max in every litre of sweat.

Thus, the theory that muscle cramping is caused by low electrolytes as a result of sweating cannot be true. You definitely lose more fluid (or water) than sodium when you sweat.

Sports drinks are incapable of maintaining your body's sodium levels during exercise despite what the manufacturers and advertisers tell you. The sports drink industry has created a perception  that its electrolytes that will help prevent a decrease in sodium.

As explained above, sweating does not decrease your sodium levels, it causes an increase in sodium levels. Sports drinks actually contain insufficient sodium to counteract the effects of sweating on the blood's electrolyte concentration. In fact it causes your sodium levels to fall further.

A sports drink usually contains approximately 18mM of sodium (or 0.4 grams of sodium per litre). That means if you drink a litre of Gatorade (or 100 plus, Powerade etc) during exercise, you can replace a litre of fluid, but only 0.4 grams of sodium.

Blood normally has 1.4 grams of sodium per litre, so even a sports drink replaces more water relative to salt and will only lower your sodium concentration. You CANNOT elevate or even maintain your sodium levels by drinking a sports drink. It is impossible.

Of course if the alternative to sports drink is water, then sports drinks can help prevent sodium levels from falling further.

The key point is that a sports drink will still cause a decline in sodium levels, though less compared to water.

The act of drinking is what causes the reduction. To prevent your sodium levels for dropping further, you're better off not over drinking in the first place.

It's better to listen to your body and obey what it suggests you to do.

Now you know.


Science of Sport - Sports drinks, sweat and electrolytes Part 1

Science of Sport Muscle cramps Part IV

Dugas J (2006). Sodium Ingestion And Hyponatraemia: Sports Drinks Do Not Prevent A Fall In Serum Sodium Concentration During Exercise BJSM. 40: 377. DOI: 10.1136/bjsm.2005.022400.

Sports drinks we have in Singapore
If I have to, I prefer Pocari- "tastiest" to me

Sunday, August 2, 2015

What Causes Muscle Cramps?

Picture by Jon Candy from Flickr
A patient came in to see me yesterday and complained  that if not for a muscle cramp near the end of her recent race, she would have won her age group and also gotten a personal best timing.

After putting it up on Facebook, she had many, many unsolicited comments : Eat bananas, take salt tablets, drink Gatorade, have some pretzels. Knowing that I used to race, she wanted to know my thoughts and get some advice on how not to cramp during a race.

While her friends and even strangers who posted on her Facebook page meant well, none of their advice will help her as even expert exercise physiologists can't say for sure what causes exercise induced cramps.

The most common and popular theory on cramps is that they are caused by sodium (or salt) loss and dehydration. Fluid and electrolyte loss. This has been the focus of much Gatorade (or other companies) sponsored research. More on that in another post definitely.

Tim Noakes, possibly the most renown sports scientist on this topic found no significant differences in sodium and magnesium levels of 72 ultra marathoners between those who cramped and those who didn't cramp. There was no differences in body weight, plasma (or blood) volume between the two groups, showing that dehydration had no real effect on cramps.

Dehydration could however hasten muscle fatigue. And this is what Noakes and most exercise scientists believe is the likely cause of cramps.

In the above ultra marathoner study, 100 percent of the runners cramped in the last half of the race or right after the race. Think about it, when was the last time you had a muscle cramp? At mile 20 (or 32 km) in a marathon or after 3 km in a 5 km race?

This explains why cramping is most likely to occur during races than training. You tend to start off too fast or you pushed yourself too hard. Other studies have found that tough, hilly course and poor pacing (starting too fast) are predictive of muscle cramps.

So, anything you can do to prevent muscle fatigue should then help to prevent cramps. The obvious though undesirable strategy is to simply slow down. Not exactly what you would want to hear or read!

Since guarding against muscle fatigue is key, you can't take any short cuts in training. Train more, do longer distances. You simply have to adapt to the distance you want to race. There is no substitute for strength work that is running specific. Gotta love hills and speed work.

Plyometrics (or explosive exercises) may improve the endurance of the receptors in your muscles that are thought to cause muscle cramps.

Knowing your own capabilities is key as you can choose a pace right from the onset of the race. Cramps are more likely to happen to athletes who start too fast.

"That's it"? My patient said. Yes, that's it.


Schwellnus MP, Nichol J, Laubscher R and Noakes T. (2004). Serum Electrolyte Concentrations And Hydration Status Are Not Associated With Exercise Associated Muscle Cramping (EAMC) In Distance Runners. BJSM. 38: 488-492. DOI: 10.1136/bjsm.2003.007021.