The Latest on Antioxidant Supplementation for Endurance Athletes

The following is an article that I found on the American College of Sports Medicine's newsletter. Further proof that good nutrition is found in real food, not pills or powders.

Active Voice: Understanding the Use of Antioxidant Supplementation with Exercise
By Allan Goldfarb, Ph.D., FACSM, FNAK

Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily reflect positions or policies of ACSM.

Allan H. Goldfarb, Ph.D., FACSM, FNAK, is Professor in the Department of Kinesiology at the University of North Carolina in Greensboro. His research focuses on the interaction of reactive oxygen species and antioxidant supplementation during exercise. He has published numerous research articles on this topic, as well as several reviews and book chapters. In the March 2011 issue of Medicine & Science in Sports & Exercise® (MSSE), Dr. Goldfarb coauthored related research entitled, “Effects of a Fruit/Berry/Vegetable Supplement on Muscle Function and Oxidative Stress.”

There is a great deal of conversation surrounding antioxidant supplementation and the potential need for these substances. There are numerous advertisements on the market for antioxidant vitamins and for packaged items touting that they contain antioxidants. The idea that antioxidants are necessary comes from the concept that they protect the body against harmful substances known as reactive oxygen species (ROS), or radicals. These radicals are typically molecules with an unpaired electron. Because they have a negative charge, they seek a balance and typically react with other molecules. This interaction often changes the affected molecules and could damage them. However, we now know that these ROS are important signaling molecules that help direct cellular action.

The initial studies conducted with exercise tried to establish if there was a resulting increase in these ROS or their byproducts in either blood or muscle. This was indeed the case, depending on the intensity and duration of the exercise, but results may differ based on the type of exercise employed. Numerous studies have subsequently researched the effectiveness of antioxidant supplementation to reduce the increase in these ROS or their byproducts to these same exercises. The results from these studies are not consistent, and these inconsistencies appear to be influenced by the type and/or dose of antioxidant used and the timing of supplementation. However, most of the studies have shown some positive results in the reduction of ROS (or byproduct) accumulation but little change in functional measures, such as altered force, improved performance and fewer injuries. Our recent findings reported that intake of antioxidants to prevent accumulation of ROS byproducts in the blood did not change the loss of force or range of motion after subjects performed a damaging eccentric exercise bout (delayed onset muscle soreness). This study supports the concept that one can separate out this modest change in ROS from the actual processes associated with muscle breakdown to eccentric exercise.

Other recent evidence has reported that taking antioxidant vitamin supplementation may interfere with some of the important adaptations that occur with exercise training. It was recently reported that the adaptations to up-regulate the antioxidant defense system was inhibited by taking antioxidant vitamins during the training program. In addition, taking antioxidant vitamins was noted to prevent training-induced enhanced glucose transport into the cells. Therefore, it is strongly suggested that we think twice about taking antioxidant supplements routinely. There appear to be only modest gains from this, and perhaps some important losses may even occur, as ROS are important signaling molecules to help the body adapt to the overload of exercise training. Also, more studies are clearly needed to establish if naturally occurring antioxidants in our foods (e.g. polyphenols) would have the same beneficial inhibitory effects as observed with the antioxidant vitamins.

In conclusion, if you have a well-balanced diet and if you exercise routinely, you probably do not need antioxidant supplementation. If your diet is not well-balanced, consider adding enough fruits and vegetables to obtain your natural antioxidants.

Hydration and marathon (and other endurance events)

There is quite a bit of confusing information floating about on hydration strategies for marathon and other long-distance events. Misleading data can even be found in otherwise very reliable sources. For instance, a few months ago I read an article on running.competitor.com (a website I visit regularly and which usually has great content and provides solid advice) that gave outdated recommendations on this very subject. My intent here is to clarify the prevailing science behind this perplexing topic. For the sake of simplification, I will focus mostly on marathon running, but this applies to longer distance triathlons as well (half-ironman and ironman). 

For a long time dehydration was the nemesis of participants in marathon. A lot of studies done in the latter half of the twentieth century noted the negative effect dehydration has on performance. Others focused on the role that dehydration may play in the development of heat illness. After that information came out, along with the fact that hydrating while exercising can enhance performance, there was a big push to have people aggressively hydrate during exercise, especially in marathons. At the same time, marathons were becoming en vogue among the "non-elite" population, exploding in popularity with several thousands in the larger events. 

With this new data came companies such as Gatorade which helped push this doctrine to the public through advertising. However, a deadly side effect of this is what is called Exercise Associated Hyponatremia (EAH), hyponatremia meaning low sodium concentration within the bloodstream. What started to happen was that participants, mostly in marathons, were actually over-hydrating, diluting out their sodium so severely that in the most dire cases several actually died. Some may have heard of this as "water poisoning".

Over-hydrating is an oversimplification actually. There are a couple of other theories about why this happens (abnormalities in the secretion of water-conserving hormones and transfer of sodium between tissues) but there's no getting around the fact that the majority of EAH patients actually weigh more at the end of the race than they did at the beginning, and they report an intake of several liters of fluids during it. 

It is also worth mentioning that the loss of sodium through sweat has NOTHING to do with EAH. Sweat is hypotonic, meaning that it has a lower sodium concentration than our blood, and thus it would have a greater chance of increasing the sodium concentration than decreasing it. The important thing to remember here is not the actual quantity of sodium ions in our body but rather its concentration within our blood and other tissues. 

If you watch enough of the Gatorade and Powerade commercials you may be led to believe that you can prevent electrolyte abnormalities if you drink these products during and/or after exercise. False. There have been a few studies that looked at the difference between drinking water and sports drinks (those containing carbs, sodium, and potassium) and the incidence of EAH: there was NO difference. So drinking Gatorade or Powerade or a similar beverage during a marathon instead of water will not prevent EAH. There's not enough sodium in them to make a difference, they are hypotonic relative to our body fluids. However, I have to say that they are likely better than water alone simply because of the carbs in them, but they do little to restore electrolytes if imbibed during a race or workout. In fact, they contain sodium mostly to improve the taste and also to help with the absorption of the carbs; the receptors in the intestinal cells that absorb glucose need to also have a sodium ion attached in order for it to function. 

So what should you do? Here are a few items that I hope will prove useful:

1. Do NOT listen to anyone who says you need to drink a set amount of fluids per hour of a marathon or who says you must drink at every aid station

This is outdated information! Do not pay any attention to it! 

2. Do drink fluids while exercising longer than one hour

It's ok to drink during these races and training runs, in fact it is still recommended, but err on the side of drinking only to thirst. This will prevent severe dehydration but minimize risk of over-hydration. Heck, sometimes I drink during shorter runs of maybe 30-40 minutes if it's hot or dry enough out or if I'm doing a hard interval workout. 

3. Take in carbs during the race and in longer training bouts

You are better off drinking sports drinks than water, if your stomach can tolerate it, but only because of the carbs in them, not the electrolytes. If you can't tolerate the sports drinks, then try eating energy gels or bars or other sources of carbs while drinking water for fluids. Again, it is best to try out these things during training. Don't wait until race day to try something you haven't already gotten used to.

4. Monitor your urine output

You should not find yourself urinating very light colored urine or very frequently in the latter half of a marathon. This means you are over-hydrated and risking EAH.

5. Monitor for swelling

You should also not be getting swollen ankles, hands, or fingers during a marathon, this is another potential sign of EAH.

6. Stay cool

If it's really hot out, the water at the rest stops may be more beneficial dumped over your head than down your throat, as long as you're not overly dehydrated. This will do far more to cool you down and prevent heat illness. 

Lastly, there have been very few reports of EAH in endurance cycling events, so there's less need for concern in this area. However, the same hydrating principles apply. 

As they say, all things in moderation.

Altitude Problem

I just read an interesting article in "Inside Triathlon" by Matt Fitzgerald about the whole idea of the benefits (or lack thereof) of living and training at high altitude.  For a long time people have associated living at high altitude to providing an endurance benefit versus those who live and train at low altitude. Hence all the endurance pros living in Boulder, CO (5400 ft), and Mammoth Lakes, CA (7900 ft), among other places. Also, the US Olympic Training Center is in Colorado Springs, CO (~6200 ft). One can name other high altitude locales with close affiliations to the endurance community: Park City, UT (~7000 ft); Flagstaff, AZ (~6900 ft); Vail, CO (~8000 ft); Lake Tahoe, CA (~6200 ft); Santa Fe, NM (~7000 ft) to name a few. The list can go on and on. But do athletes who live in these towns perform better than those who live in San Diego, Boston, NYC, or Fargo, ND? Not necessarily. There are many, many factors involved in endurance sports, which is why it is so tough not only to be competitive in them but also to scientifically investigate them as well.

Altitude Basics
New insight into the altitude question arose a few years ago when exercise physiologists delved into its impact on fitness. The theoretical advantage of altitude lies in its ability to stimulate an increase in red blood cell mass in our bodies; in effect a natural, physiological blood doping. The relatively lower air pressure at higher altitude leads to lower transfer of oxygen into our bloodstream from our lungs. This leads to a relatively lower level of oxygen in our blood. Our body senses this lower oxygen level and is stimulated to produce more red blood cells in order to try to increase the amount of oxygen in the blood; more red blood cells means more oxygen carrying capacity, which in turn means a more efficient cardiovascular system. This process takes several weeks, though, so going to altitude for only a few hours at a time will do you no good. One needs to spend the majority of one's time at altitude (at least 16 hours per day) over at least 3-4 weeks in order to reap this benefit. This adaptation provides an increased ability to perform exercise at that altitude, and allows for a greater ability for endurance exercise at sea level as well.

The Altitude Problem
However, if you train at altitude, you are not able to push yourself to the extreme limit you would be able to at a lower elevation. Even though you have made some adaptations to account for the lower oxygen access, you still don't have the access to oxygen you would have at sea level. So for instance, if you do interval training at higher altitude you could only hit sub-maximal speeds compared to what you would hit at lower altitude. A result of this discovery was the "live high/train low" principle. By living at 6000 ft or above and training at 4000 ft or below, you can physiologically blood dope and still train to a maximal level. A study done by James Stray-Gunderson and Ben Levine found that those who lived high/trained low performed on average about 1.5% better than those who either lived high/trained high or lived low/trained low.

Tricks of the Trade
What does that mean for the pros? Some athletes are able to live in places where they can live and do most of their training at high altitude and but have relatively easy access to lower altitude for their more intense training sessions. Still others live and train low but sleep in low-oxygen tents to simulate the relative hypoxia of higher altitude. The only problem with this strategy is that if you're only sleeping in them for 8-10 hours per day, you may not be gaining any benefit from them. Recently some have been living and training at high altitude but will use supplemental oxygen for their intense sessions.

Plight of the Lowly Masses

What does that mean for the average weekend-warrior endurance athlete? Not much. It's rare that one can find oneself in an area where one can live at higher altitude and have easy access to a lower altitude. Plus, 1.5% does not account for much unless you are highly competitive/elite and shooting for an overall or age-group podium in competitive races such as sprint or olympic distance tris or half- or whole marathons. Longer distance races are tougher to show benefits since there are many more factors involved in performance over that duration. But, it does mean that going to high altitude for high intensity training sessions will be a waste of your time and energy, and may actually be detrimental, unless you simply want to see how your body responds to the higher altitude. If you already live at high altitude, you may have the advantage of being able to endure lower to moderate levels of exertion over longer races at lower altitudes but you may not necessarily be any faster.

So keep on keeping on wherever you are, any fitness is good fitness. 

Heat Acclimation

Interesting article on heat acclimation and improved performance in cooler temperatures. Maybe there will be a new push for "live hot and train/race cool"??

http://www.medicalnewstoday.com/articles/205744.php

Exercise and Your Immune System

This topic has a special significance for me right now as I am currently getting over a nasty cold (upper respiratory tract infection, or URTI). Some of you may have come across this, especially as you ramped up training in anticipation of a half- or full marathon, a longer distance triathlon, or really for any distance race. Others may notice that they don't get sick as much anymore after they initiated a moderate daily exercise regimen.

Well, there's science to back this up. While there's still a lot of unknowns in this area, it is well documented how the immune system is affected by exercise. Whether or not this directly affects susceptibility to URTIs is debatable. It is complicated by the fact that there are so many other variables that influence our immune system:

• proper diet
• proper hydration status
• adequate sleep
• stress
• proper hygiene
• infectious exposures
• cold weather exposure
• rapid weight loss

Regardless, it has been hypothesized that daily moderate exercise is protective when it comes to URTI rate, whereas intense exercise actually increases URTI risk. This has lead to the J curve, which is a graphical representation of this:

There is still some debate about this, but it has held up so far. In fact, an article just came out in the British Journal of Sports Medicine that reports up to a 46% reduction in URTIs in those who exercise 5x weekly versus those who exercise once or less per week. So, for those of you who do not engage in daily moderate exercise, here is another reason to do so! Since we have yet to come up with the cure for the common cold, why not just prevent it?

For more info on this recent article, check this out:

http://www.medicalnewstoday.com/articles/206417.php

On another note, those of you who are training more intensely or racing, it is best to be very careful about being exposed to illness in the few days before a race or a hard workout, as you are twice as likely to get a URTI in the 2 weeks after a marathon or equivalent race/workout versus those who aren't racing or training intensely. If you are starting to get symptoms of a cold and you have a tough workout coming up, it may be better to postpone the hard workout until you are feeling better. It may mean less time off in the long-run (pun intended).

That being said, if you have a cold but you feel ok, there is no reason you can't go out for a run or a bike ride, just make it an easier workout. However, if you have a fever, bad cough, or are feeling really sick, it's best to take at least that day off and not exercise. Your body will thank you, and you'll get back out there much sooner.

New Blog

Well, this is the first entry in my new sports medicine blog. My hope for this is threefold:
1) that I can use this for myself, to keep track of all of the new information I come across on my daily purviews of the medical literature as well as interesting stories;
2) that it will help others who have the same interests as I gain a greater understanding of the issues that endurance athletes face;
3) and that I can help those who are interested in or considering becoming more active to have the best information available to do so.

I have seen a few blogs/websites of sports medicine providers that seem suspect to me; they appear to be more interested in making a quick buck than in providing quality, objective information to their readers. And I don't have to remind you that there are plenty of companies out there that are pushing diet and weight loss products, as well as exercise/endurance aids, based on very little--if any--scientific evidence.

The plan is to pick a topic, hopefully weekly, maybe more realistically monthly, and present information on it from current evidence-based knowledge. I will likely post interesting stories as well.

Some possible topics:

1. barefoot running/running shoes
2. ergogenic aids
3. overuse injuries
4. joint/tendon injections
5. injury prevention
6. current treatments (PRP, prolotherapy, etc)
7. relationship of exercise and immune system
8. concussion
9. "exercise is medicine"
10. weight loss
11. metabolic syndrome
12. diet/nutrition

And hopefully more. I welcome any comments and suggestions.