Are Sports Drinks Overhyped?

My patient was asking me what I fuel myself with for my weekly Saturday bike rides. He knows I usually ride between 70-90 km. He was shocked when I said that I only bring a banana and a bottle of water with a slice of lemon for taste. 

Perhaps he had been influenced by social media and advertisements, and felt that hydrogels, superstarch, theanine, isotonics and even coconut water packed with potassium were better for absorbing carbohydrates into our system while exercising.

SuperStarch?

Perhaps some of the latest choices mentioned earlier may give an extremely small edge. Do they perk you up in the morning, help you metabolize energy, increase your focus and 'protect' your body as they claim? Especially since none of them are solidly backed by research. Will you go and order the latest offerings? 

I've written before that sports drinks definitely cannot replace your sodium levels during exercise. What it can definitely do is to provide you with some carbohydrates for fuel during prolonged (longer than 90 minutes) exercise to sustain your level of performance.

Results suggest that sports drinks can fuel you to maintain athletic performance. In the article referenced below, the authors wanted to know if a pre-exercise meal affects sports drink effectiveness. The subjects (cyclists) rode 105 minutes at lactate threshold followed by a 10 km time trial under 4 conditions. No breakfast before the ride with a placebo sports drink. No breakfast with a real sports drink. Breakfast with a placebo sports drink and breakfast with a real sports drink.

The breakfast the riders had were consumed 3 hours before the exercise. It had 824 calories, consisting of two thirds conbohydrates. The real sports drink had 8 percent maltodextrin (works like glucose but has no taste) while the placebo was just artificially sweetened. The sports drink was consumed every 15 minutes during the first 105 minutes ride and halfway mark of the 10 km time trial. 

Those who had the real sports drink with breakfast managed 198 watts in the time trial, those without 197 watts, not much difference. Strangely enough the results did not give any boost to the cyclists who fasted (no breakfast). I would have thought that the sports drink would help those who did not eat breakfast, ride better. Other studies did find a difference. Using the real sports drink helped with or without breakfast. 

There was definitely a negative effect for those who skipped breakfast without the real sports drink. With breakfast but no sports drink the cyclists managed 173 watts, with no breakfast, no sports drink it was 154 watts. They also had the highest rate of perceived exertion.

Note that at the start of the time trial, those who had breakfast with placebo drinks kept up with those with breakfast and real sports drink. As the time trial progressed and fuel stores were used up, those without the real sports drink fell farther and farther behind since their placebo drink failed to fuel them. 

This study shows that consuming carbohydrates during prolonged exercise definitely makes a difference. What I liked about the study was that the subjects did not know if their sports drink was real or placebo. The time trial started only after 105 mins, long enough for carbohydrate stores to be depleted. There was also no funding (from the sports drinks industry) for this study, so less chance of any bias.

If you are out racing or training for a few hours or more, commercial sports drinks aren't the only option. Neither is hydrogel, superstarch or any of the latest offers. Many sports drink companies may advertise their specialized formulations, but the 3 basic ingredients needed are water, sugar and salt. Beyond these 3 ingredients the science gets a lot weaker. 

Many triathletes drink flat Coke (see picture below) in the Ironman events and eat bananas or dried figs. I'll usually just have a banana, dried raisins or dates. Just make sure you have something to suit your palate. Oh! And remember not to skip breakfast.

Reference

Leari SK, Ghiarone T, Silva-Cavalcante MD et al (2019). Cycling Time Trial Performance Is Improved By Carbohydrate Ingestion During Exercise Regardless Of A Fed Or Fasted State. Scan J Med Sci Sp. 29(5): 651-662 DOI: 10.1111/sms.13393.

You can the dark Coke stains on the front Mark Allen's top after beating Dave Scott after 6 attempts and finally winning at the 1989 Hawaii Ironman. 

*Picture taken from my book Ironwar by Mark Fitzgerald, Velopress 201.

What is More Helpful Than Electrolytes In Preventing Muscle Cramps?

I don't believe this. Many athletes still do not know what causes muscle cramps. In a survey of 344 endurance athletes published last year, 75 percent believed that taking extra sodium would help prevent their muscles cramping (McCubbin et al, 2019).

The usual and common theories for muscle cramps are loss of electrolytes (sodium, potassium and magnesium) and dehydration (fluid). Suggestions to combat cramps are to eat more bananas, take more salt/ sodium, magnesium supplementation, drink Gatorade etc. None of which will really help.

Having written on muscle cramps a few times, I'm most interested when new research suggests alternative ways to beat muscle cramping.

The researchers (Martinez-Navarro et al, 2020) recruited 98 runners running the Valencia marathon of which 84 (72 males, 12 females) completed the study (all pre and post race testing). 

20 runners suffered muscle cramps during or immediately after the race. Blood and urine tests showed no differences in dehydration and electrolyte levels before, during and after the race for the runners that cramped versus those that did not.

What the researchers found was a big difference in creatine kinase and lactate dehydrogenase which are both markers of muscle damage. These markers were significantly elevated immediately post race and 24 hours in those runners who had cramps.

There was also no difference when the runners did their last training run prior to the race nor any sign of elevated muscle damage in pre race tests. Hence, the runners who cramped did not have any muscle damage (from not tapering/ resting or backing off from training). 

Almost all the training variables between the two groups were similar. Weekly mileage, previous marathons ran, etc were all similar save one variable. 48 percent of those who did not suffer from cramps did regular lower body strength training compared to 25 percent of those who cramped.

This adds more weight to my previous post that muscle cramps are more likely to occur in muscles that are tired/ fatigued to the point of damage.

I would like to add that dehydration and electrolyte depletion can hasten muscular fatigue which then causes muscle cramping.

If you're still struggling with muscle cramps, it's definitely worth giving lower limb strength training a shot and for it's other benefits as well. 

Another researcher (Del Cosco et al, 2013)who wrote about muscle damage causing one to slow down at the end of marathons suggested lower limb exercises up to 80 percent maximum weight you can lift to protect your legs from damage.

References 

Del Cosco J,  Fernandez D, Abian-Vicen J et al (2013). Running Pace Decrease During A Marathon Is Positivively Related To Blood Markers Of Muscle Damage. PLoS One. 8(2): e57602. DOI: 10.1371/journal.pone.0057602

Martinez-Navarro I, Montoya-Vieco A et al (2020). Muscle Cramping In The Marathon: Dehydration And Electrolyte Depletion Vs Muscle Damage. J Stren Cond Res. DOI: 10.1519/JSC.0000000000003713.

McCubbin AJ, Cox GR et al (2019). Sodium Intake Beliefs, Information Sources, And Intended Practices Of Endurance Athletes Before And During Exercise. Int J Sp Nutr Ex Metab. 29(4): 371-381. DOI: 10.1123/jisnem.2018-0270.

How To Beat Muscle Cramps? Sunday Times Article

Sunday Times article 280719

Today's Sunday Times article on training for the Straits Times run says avoid muscle cramps by consuming more sodium? Nah, not totally true. Not at all actually. I've written about this exact same topic way back in 2015.

In that post, I wrote about how renown sports scientist Tim Noakes found no significant differences in sodium and magnesium levels in 72 ultra marathoners among those who cramped and those who did not cramp (Schwellnus et al, 2004). They found that sweating too much had no real effect on muscle cramps.

Try to think of when you last had a muscle cramp? After running 30 km in your marathon or after 3 km in a 10 km race?

Muscular fatigue (or when your muscles get too tired) is what really causes muscle cramps. The muscle cramps so you can avoid injury before you can push yourself further. That the Sunday Times article definitely got correct.  

Muscle cramping occurs mostly during races than during training. If you started your race too fast or you pushed too hard, that may cause your muscle to fatigue and then cramp. Other studies have shown that tough, hilly courses and poor pacing are predictive of muscle cramps.

I also wrote that sports drinks cannot replace your sodium levels during exercise. Your electrolyte levels actually rise when you sweat a lot. Yes, you read correctly. I'll explain this below.

Assume you have five cups of water and five teaspoons of salt/ electrolytes in your body. Say you sweat 2 cups of water and a teaspoon of salt/ electrolytes when you exercise, the concentration of salt/ electrolytes is now higher. It will remain higher as you become more dehydrated.

Apply this concept to our running physiology. Our sodium (salt) concentration 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. Even for a "salty sweater" (those who lose more salt than others when they sweat), they lose about 1.1 grams of salt max in every litre of sweat.

Hence, the theory that muscle cramping is caused by low electrolytes/ salt as a result of sweating is not true. You will definitely lose more water than sodium when you sweat. You can read more of that here.

You read it here first. Now you definitely know.

References

Science of Sport Muscle Cramps Part IV

Science of Sport - Sports Drinks, sweat and electrolytes Part I

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.

Schwellnus MP, Nichol J, Laubscher T 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.

*The Sunday Times article is on page A27 under the Sports section. Go take a look.

Which Calf Is Bigger?

Notice any difference in the picture above? If you look closely, you'll notice that the left calf is slightly bigger than the right. Upon palpation my patient's left calf does feel more "meaty" compared to his right.

This is surprising as my patient says that his right leg is his dominant leg. Usually the dominant leg is bigger and stronger than the non dominant leg.

Now, this patient, who is an ultra marathoner came in to see me yesterday after a 35 km training run in the morning. He said that his right calf muscle often cramps after about 35 km.

Even after an easy run, his right calf and hamstrings often feel more tired and fatigued compared to his left. He also felt that it required more effort to bend his left knee compared to his right.

My patient also does not have any numbness, pins and needles down his right leg or other neurological signs. After checking his back as well, I explained to my patient that the reason for his muscle cramping in his right calf muscle is simply due to muscular fatigue.

Since his left calf is bigger, it will also be stronger than his right calf. This means that after running a certain distance his right calf will work harder than the left calf and will fatigue faster too.

I explained that muscle cramping is not due to sodium (or salt) loss, dehydration, electrolyte or fluid loss. I've explained this in a bit more detail before in another post, have a read here please if you're keen.

We then discussed how he could do some isolated (right) leg training to make his right calf stronger to avoid cramping eventually.

Here in his case, size does matter.

Reference

Schwellnus MP, Nichol J, Laubscher T and Noakes T. (2004). Serum Electrolytes 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.

Which Drink Hydrates You Best?

Ever wondered which drink is best after a hard training session or race? I've written before that as a recovery drink, chocolate milk is as effective as Gatorade and even superior to Endurox.

Quite a few factors affect how quickly you pee out a certain drink. Drinks with more calories or electrolytes tend to stay in your system longer. How much you drink at a time also plays a part according to an article I read.

Researchers recruited 73 subjects to test 13 different drinks. Each subject tested water and three other beverages. At each session, the subjects drank a litre of the chosen beverage and collected their urine for the next four hours.

A "beverage hydration index" showed how much of that drink was retained after two hours compared to a litre of water.

Picture from American Journal of Clinical Nutrition

Looking at the picture above, you can see that a higher bar means more fluid retained. The dotted line represents twice the coefficient of variation away from water (meaning you can be real sure of a positive result).

The chart shows that milk stays longer in the body probably because of its calorie content. Milk and an oral rehydration solution (or sports drink, due to its calories and sodium) also stays in your system.

Personally, I was quite surprised that tea, coffee and beer did not seem to produce significantly more urine.

In fact coffee seems to have the lowest reading in the chart. The authors suggested that the diuretic properties of alcohol may be counterbalanced by its retention promoting calories (although another previous study that compared regular and alcohol free beer showed that regular beer drinkers had 12 percent more urine).

The authors also pointed out that larger doses of caffeine or alcohol may trigger more urine

Well, now you know not all drinks take the same time to reach your bladder. Choose your drinks wisely after your hard training session or race.


Reference

Maughan RJ, Watson P et al (2016). A Randomized Trial To Asess The Potential Of Different Beverages To Affect Hydration Of Different Beverages To Affect Hydration Status: Development Of A Beverage Hydration Index. Am J Clin Nutr. 103(3): 717-723. DOI: 10.3945/ajcn.115.114769.

Drink It or Pour It?

Picture by richseow from Flickr

You've often seen the elite athletes pour water over their heads to cool themselves while racing. So is it really better to pour the water over your head on a really hot day or is it better to drink it?

Picture by richseow from Flickr

Well, here are some numbers obtained in the paper referenced below. In the article, kilojoules and calories are a measure of the energy dissipated as heat. The heat is produced as a by product of muscular exertion, which is powered by the energy from food.

Drinking a 250 mL cup of water at just above freezing ( 1 degree Celsius or 34 degress Fahrenheit) helps you get rid of 39 kJ of heat (about 9 calories).

If you drink a slushie that is half water and half ice, it's better as the ice can melt inside your body. A 250 mL slushie will get rid of 81 kJ of heat (or 19 calories).

Pouring a 250 mL cup of water on your head will get rid of 607 kJ (145 calories) if the water can be spread around your body surface so it all evaporates rather than dripping to the ground. Yes, evaporation is a great way of dissipating heat.

But, that's a very big "if" in my opinion as it's hard to pour a bottle over your head without spilling any water. although the authors suggested that even if you spill 85 percent of the water you still get more heat loss from pouring than from drinking the slushie.

Do take note that the water you pour over yourself has to evaporate. If it's a hot and super humid day like it always is in Singapore where your sweat is dripping like there's no tomorrow you won't have the water evaporating. Pouring cold water over your head probably makes your feel cooler (and hopefully better) for a while.

It works best when the weather is dry and breezy so that your sweat can evaporate. (Local runners who race overseas take note).

My suggestion would be to drink when you need and pour some cold water over your head and neck too to cool off if you don't mind your running shoes getting a little wet.

Best to be sure it is water and not a sports drink that you pour over yourself. Yes, I've accidentally poured 100 Plus over myself before when I was racing, so beware.


Reference

Morris N and Jay O (2016). To Drink Or To Pour: How Should Athletes Use Water To Cool Themselves? Temperature. 3(2): 191-194. DOI: 10.1080/23328940.1185206.

Pepsi Light Dumbell?

Taken online with my Iphone 6 from AlmapBBDO

If you're thinking April Fool's you are absolutely correct.

The picture was circulated by an ad agency (AlmapBBDO) in Brazil. Turns out the bottle isn't real and there are no plans to create one according to a spokesperson from PepsiCo.

If PepsiCo eventually does manufacture the two litre dumbell lookalike bottle, it'll be a good advertisement for them but a nightmare for gym goers trying to lose weight. What I suggest is to fill the bottle with water or sand instead. Now that would be good for a workout.

Perhaps Gatorade (a brand owned by PepsiCo) would be more suitable to manufacture it.

Happy April Fool's Day.

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.

Chocolate Milk, Gatorade or Endurox

I don't know about you but for me, I'll choose chocolate milk every single time. Plus you know what, my choice happens to be backed by scientific research.

Allow me tell you more. I've often been asked by friends, patients and even my competitors what I eat/ drink for my recovery after a hard training session or race. I'll tel them usually I'll eat/ drink whatever I fancy or whatever I find in the fridge at home. Most of the time it's an ice cold Coke and/or chocolates, chocolate milk, chips etc. I always get an incredulous look from my friends especially." Are you allowed to do that?" Well, the study below actually says I may be right. Well, ( I don't know about Coca Cola or chips), but with regards to chocolate milk anyway.

Published in the International Journal of Sport Nutrition and Exercise Metabolism, Karp et al, 2006 found that chocolate milk was an effective recovery aid, similar to Gatorade and superior to the more expensive Endurox. For athletes training twice per day, chocolate milk is an effective recovery aid. Plus they taste a lot better to me than Gatorade or Endurox anytime.

Reference

Karp JR, Johnston JD et al. (2006). Chocolate Milk As A Post-exercise Recovery Aid. Int J Sport Nutr Ex Metab. Feb; 16(1): 78-91.

We drink Oat milk now, not cow milk