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.

References

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.

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.

References

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

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.

Reference

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.

Ice Vest Improve Your Race Performance?

Cooling vests by Cozy winters

You may have seen elite athletes (like Alberto Contador above) donning an ice vest prior to their events and wondered if that really helps. Well they do, but a recent study showed that precooling your legs may be much more effective (than an ice vest) before a race in hot, humid conditions.

The researchers had their runners complete three randomized 5 km time trials on a treadmill in a laboratory at about 90 degrees Fahrenheit (about 32.2 degrees Celsius) and close to 50 percent humidity.

The runners did a 30 minute warmup consisting of jogging, static and dynamic stretches, more jogging and some short strides to finish.

One group of runners did warmup with an ice vest and another with ice packs covering the thighs (the researchers developed shorts with pockets on the front and back of each high to hold frozen gel packs). The third group was a control group with no cooling devices.

The runners' core and skin temperature, heart rates, perceived rates of exertions were measured during the time trials. Runners with ice packs on their thighs ran the 5 km 85 seconds faster than the control group. Those with the ice vests ran 45 seconds quicker than the control group.

The 5 km times in the study were a lot slower than the runners' own personal bests (19:30 on average compared to 23:45 min after the thigh pre cooling). The authors suggested that this was due to the hot conditions, the fact that the runners could control their pace on the treadmill and that they were not in a race environment.

The authors suggested improvements even in cooler conditions, down to 70 degrees Fahrenheit (or 21.1 Celsius).

The authors cautioned that not everyone will shave 85 seconds off their 5 km race times if you employ such a strategy before your next race in the heat, but there will be some level of benefit.

This study is unique as the runners performed an active, sport specific warmup before the race to mimic what runners actually do before a race.

The authors suggest using an elastic bandage over frozen gel packs on your thighs as an alternative to ice shorts or vests.

Oh, and remember to drink a slushie too.

Reference

Randall CA, Ross EZ et al (2015). Effect Of Practical Precooling On Neuromuscular Function And 5-km Time-trial Performance In Hot, Humid Conditions Amonh Well-trained Male Runners. J Strength Cond Research. 29(7): 1925-1936. DOI: 10.1519/JSC.0000000000000840.

From Amazon

Protein Before Bed Builds Muscle

Night time snack before zzzzz

You can't simply build muscle eating lots of protein. To build muscle you need a combination of resistance training and protein. Recent studies show that the most effective way to trigger muscle growth is to spread your protein intake in several doses of 20-25 grams throughout the day.

A group of researchers have previously demonstrated that if you consume protein right before sleeping it can increase the rate protein synthesis (the process of making protein) by 22 percent during overnight recovery from exercise.

This same group of researchers now wanted to know if consuming protein before bed would increase the muscle adaptive response to weight training.

They did a 12 week double blinded study on a bunch of volunteers who weight trained three times a week. The subjects drank either a protein drink or placebo before bed. The protein drink contained 27.5 grams of protein and 15 grams of carbs.

The results showed that the group that had the protein drink had significantly greater improvements in muscle strength, muscle size and even muscle fiber size (done by muscle biopsy).

The subjects were already consuming diets that were fairly high in protein (1.3 grams/kg) and they also had a protein snack (10 grams of protein) after each workout.

How should you snack up on your pre bedtime meal? A cup of milk has about eight grams of protein, and if you had some toast and peanut butter that will probably do the trick.

Don't forget to do strength train too.

Reference

Snijders T, Res PT et al (2015). Proten Ingestion Before Sleep Increases Muscle Mass And Strength Gains During Prolonged Exercise Training In Healthy Young Men. J Nutri. 145(6): 1178-1184. DOI: 10.3945/jn.114.208371.

How Much Water To Drink After Exercise?

Picture by Daniel Orth from Flickr

I was reading a paper on the 24-hour hydration status in runners after a dehydrating run and testing what measurements are reliable to detect this when I thought of a very funny thing that happened at the Olympics.

As Team Singapore's Physiotherapist at the Beijing 2008 Olympics, other than treating the athletes, I was sometimes roped in to help test our Singaporean athletes' hydration status (since we only had one nutritionist and no exercise physiologist at the games).

Director of High Performance and other senior management at Singapore Sports Council (now SSI) decided that in order to perform well and/ or win medals, our athletes needed to be amply hydrated at all times.

Some of our athletes complained about this rather strongly as they were asked to drink more water when their hydration status showed that they needed more fluids. These athletes complained that after consuming more water they had to get up in the middle of the night to pee and afterwards could not fall asleep again for a long time.

You know what they did? They simply added water to their urine samples to pass the hydration test. Our staff got their testing done, the athletes got their much deserved sleep. Team Singapore won the medals they came to win. Win win situation for all parties. No names will be mentioned to protect the athletes involved of course.

Anyway, back to the study.

The group of runners in the study ran in hot conditions until they lost about three percent of their starting weight on three occasions. The three rehydration protocol was either 3.2, 4.2 or 5.2 litres of fluid over the next 24 hours.

Rehydration in the first 24 hours were assessed by measuring body weight of the runners, urine colour, urine specific gravity (a measure of urine concentration) and reported thirst sensation.

The most sensitive marker for fluid consumption during the first 12 hours was urine specific gravity. (Atago - which measures devices to measure specific urine specificity was used and they also sponsored this study).

Thirst emerged as a very sensitive and reliable marker by the end of the 24 hour period. The problem is that differences in thirst did not appear after the run but only emerged the next morning so you may go to bed not knowing you've not drunk water.

When the runners drank a lot, they urinated more, when the drank less, they urinated less. You may be surprised with this but when food and fluid intake were tightly controlled, the runners' body weight was unable to detect low fluid intake. The researchers concluded that body weight wasn't a particularly helpful way of tracking how much you're drinking.

There were only subtle changes in urine colour when measured on the researchers 8-point scale. So you have to pay close attention to the shade of your urine colour should you choose to to use this cue.

4.2 litres corresponded to replacing about 100 percent of the sweat losses within the first 12 hours of their run and 200 percent within 24 hours. This was sufficient to return the runners to normal by the time they were ready to run again the next day.

Turns out it corresponded most closely to how much the runners would have normally drunk too.


Reference

O'Neal EK, Stevenson MC et al (2015). Hydration Assessment Technique Over 24-h Post-run With Low, Moderate, And High Fluid Replacement. ACSM Annual Meeting. May 28, 2015. Abstract here.

With the then Singapore President at the 2008 Olympics

Blood Poisoning In Extreme Endurance Events

Picture by orangefan_2011 from Flickr

If you haven't trained hard enough for your upcoming marathon or ultra marathon race, beware for there may be more adverse effects than you think.

Extended exercises beyond four hours can put your body at risk if you are not sufficiently prepared. Stomach bacteria may seep into your bloodstream and cause poisoning.

Two different studies looked at runners taking part in two different ultra distance races in Scotland (between 78-130 miles) and Spain (5-day 143 miles stage race).

Before and after the races, blood samples were taken from the runners and a control group not racing.

Blood markers in most of the runners after the races showed traces of blood poisoning. This was similar to what you see if you were admitted to the hospital for food poisoning. Almost all the runners had stomach issues during the race as well. None were hospitalized though.

Some runners even had blood markers resembling those who have sepsis - a potentially life threatening illness where chemicals released into the bloodstream to fight infection actually generate heavy inflammation.

This happens when blood moves away from the stomach area to the working muscles when we exercise. This causes the stomach wall to spread apart and leave open gaps. Endotoxins (naturally occurring bacteria in the stomach) fit through these gaps and leach into the blood. This activates an inflammatory response in the body.

Usually the body can easily clean up this sort of bacteria leaching. Only under heavy duress the body can be overwhelmed. This can occur in extreme exercise conditions, heat stress, illness and infection.

When the weather is hot, blood flow away from the stomach to the working muscles will be more extreme, so strategies to keep the body cool during training and racing is critical.

The researchers added that repeated bouts of inflammation like this can cause long term fatigue, stomach problems and immune disturbances.

What was interesting was that in both studies, runners who trained sufficiently had higher levels of Interleukin-10, a small anti inflammatory protein that helps offsets negative health effects.

Now you know, make sure you train enough for your race.

References

Gill SK, Hankey J, Wright A et al (2015). The Impact Of A 24-h Ultra-marathon On Circulatory Endotoxin And Cytokine Profile. Int J Sports Med. 36(8): 688-695. DOI: 10.1055/s-0034-1398535.

Gill SK, Texeira A, Rama L et al (2015). Circulatory Endotoxin Concentration And Cytokine Profile In Response to Exertional-heat Stress During A Multi-stage Untra-marathon Competition. Exerc Immunol Rev. 21:114-128.