Recovery from long distance: how about a bowl of cereal?

Over the past couple of decades, much work has come out of the Exercise Physiology and Metabolism Lab at the University of Texas at Austin. Much of this work has demonstrated the positive effects of combining protein and carbohydrate intake both during and following a long bout of exercise (a few hours, give or take). The merits of carbohydrate have been well known by athletes and scientists alike but its only been recently that the significant contributions of dietary protein for endurance performance and recovery have been investigated in well controlled studies.

The group at UT Austin has a new study out in the Journal of the International Society of Sports Nutrition (Kammer et al). They attempted to make this investigation more practical to athletes by testing the effects of eating a bowl of cereal with nonfat milk against a popular carbohydrate sport drink. Twelve cyclists and triathletes (8 men and 4 women) performed two 2-hr bouts of cycling at a moderately high intensity on separate days. Following the ride, they were provided either 40 oz of sport drink containing 78.5 grams of carbohydrate or a bowl of whole grain cereal and 1/3 liter of nonfat milk containing 59 grams of carbohydrate and 7.3 grams of protein. They were also give 3/4 liter of water on the cereal day to match the fluid amount of the sport drink.

The investigators measured muscle glycogen levels (biopsy needle method) immediately following exercise and again 1 hr later. They also measured blood glucose, insulin and lactate levels. Muscle tissue was also analyzed for proteins that are involved with glycogen and protein resynthesis through the effects of insulin.

What they found:

• Insulin levels were higher during the 60-min recovery period during the cereal trial compare to the carbohydrate drink trial.
• Glucose levels were similar between trials during the 1-hr recovery.
• Glycogen resynthesis was similar between trials during the 1-hr recovery.
• Muscle tissue proteins were similar between trials during the 1-hr recovery.

What does this mean for you? If you prefer cereal and milk following a long workout or race, go ahead and eat as long as you rehydrate as well. Cereal and milk are just as effective for glycogen replenishment as a sport drink. Another way to look at this is that the protein from the cereal and milk provides no additional benefits to glycogen resynthesis as long as the amount of carbohydrates is adequate. Practically speaking, it comes down to personal preference once again. As long as you consume adequate carbohydrate and protein following a long bout of exercise, you'll do just fine regardless of the source.

The recommended amount of carbohydrate or carbohydrate + protein following a glycogen depleting bout of exercise is 1.2 grams for every kilogram of body weight per hour. For a 150 lb person, that's about 80 grams of carbohydrate or 55 grams of carbohydrate + 25 grams of protein. For a 180 lb person, thats about 100 grams of carbohydrate or 65 grams carbohydrate + 35 grams protein.

For more information on protein-enhanced supplements go to my website: http://cmierphotoandfitness.net/protein.html

Reference: Kammer et al. Cereal and nonfat milk support muscle recovery following exercise. J. Inter. Soc. Sports Nutrition, 2009.

Energy balance during multi-day backpacking

Doing field research is tough. Those extraneous variables (like the environment or exercise intensity) that scientists love to control often make interpretation of results difficult. And many times, the logistics make certain measurements impossible. Imagine trying to get a blood or urine sample from a long distance paddler during a 300-mile race. It's a catch-22 for field studies. You want to take the athlete out of the lab and place her in the environment in which she is use to training and competing. The results will have more meaning, at least to the athlete. On the other hand, you want your measurements to be scientifically meaningful and this is very difficult when they are not performed under controlled conditions. So when reputable scientists seek to study athletes under real-world situations, I have to hand it to them. A recent study with backpackers fits the bill.

Hill and colleagues studied 3 experienced backpackers during a 5-day hike on the Appalachian Trail in Virginia. The hike totaled 161.5 km (100 miles), ranging from aboutr 18 to 23 miles each day. Elevation ranged from about 660 feet to just over 4400 feet. Temperatures ranged from 46 to 72 degrees fahrenheit, not reaching over 57 degrees on most days. The three hikers were a 32-yr old female, a 34-yr old male and a 52-yr old male.

Prior to the hike, each hikers was tested in the lab to determine VO2max and to determine the relationship between heart rate and VO2 during under various walking speeds and grades and with pack weight added. A graded test was performed beginning at a speed of 3 mph and increased to 4 mph at 20% grade. Heart rate and VO2 were measured during each stage.

During the hike, a heart rate monitor was worn at all times. During rest stops lasting more than 1 minute, the hiker recorded the average heart rate response during the previous hiking interval. Resting energy expenditure was estimated based on body weight and net energy expenditure (what was spent during activity) was estimated from the heart rate response. Energy intake was measured.

On average, the hikers walked at speeds ranging from 2.1 to 2.8 mph, the fastest average speed occurring on days 1 and the lowest on days 2 and 5.

What they found:

• Average heart rate was 105 bpm
• Hikers spent almost 100% of their hiking time in light to moderate level activity
• Total daily energy expenditure approached 5000 calories on days 1 to 4
• Total daily energy intake averaged just over 2100 calories
• Expected weight loss was 1.8 kg (4 lb) and actual average weight loss was 1.7 kg
• Rate of calorie expenditure during hiking was 6.3 cal/min, ranging from 2.1 to 15.6

What can long distance paddlers take home from these data? For obvious reasons, backpackers limit their food intake based on pack weight and will almost always experience negative energy balance during multi-day hikes. This may be comparable to a paddler who limits his or her intake because of constant paddling and the inconvenience of accessing food. On the other hand, these hikers hiked for up to 8 hours a day and no more. They also hiked at relatively light to moderate intensities. No doubt, a paddler engaged in a multi-day race such as the Everglades Challenge will be expending energy at a much higher rate (at least twice as high) and continuously for a much longer period than these backpackers and thus, will experience a more dramatic negative energy balance.

Five days is not very long to determine how well the body adjusts to chronic negative energy balance and how a backpacker adjusts his or her mileage and hiking speed over the long haul. This is a good introductory study into possibly a longer study that would involve hikers during an Appalachain Trail through hike. Likewise, I would like to see studies that test paddlers under similar conditions when they are training or competing. There is much to be learned out there from paddlers who experience the real world day in and day out.

Reference: Hill et all. Energy balance during backpacking. Int. J. Sports Med. 29, 2008.

Ingesting sport drinks during exercise: does this interfer with training adaptations?

Endurance exercise training has profound effects on the structural and functional characteristics of skeletal muscle. Scientists refer to muscle's remarkable abilities to adapt to chronic exercise as plasticity. Muscle plasticity is evident by two important outcomes from endurance training, improved endurance performance and increased use of fat. The muscle's ability to use more fat is beneficial to prolonged exercise performance because it slows the rate at which muscle glycogen (a finite source or energy) is used, thus allowing the athlete more power output before fatigue. Among the specific adaptations in the muscle that allow greater use of fat are increased fatty acid transporters located in the muscle cell membrane and increased enzymes that promote fat oxidation.

We know what happens to muscle with training, but what isn't yet totally clear is how these changes are initiated. Current evidence suggests that with every bout of exercise, changes in gene expression are taking place. In this particular scenario, this means an increase in protein expression for certain proteins such as fat transporters and oxidative enzymes. Exercise provokes changes in messenger RNA which in turn increases the muscle cell's ability to produce proteins that are needed for exercise. Why an increase in fat transporters? Perhaps it is a survivial mechanism. Exercise heightens the energy state of the muscle cell, which means more energy sources and oxygen are required. From a survival point of view, if you are going to submit your muscles to this demand, the muscle will have to adapt in order to sustain such activity over and over again. It makes sense from a Darwinian perspective.

Consider the question, "What if you keep feeding the muscles glucose during exercise and by doing so suppress the use of fat?" When glucose is ingested, the muscle will prefer glucose over fat. This results in improved performance because the muscle, 1) can produce more power from glucose over fat, and 2) it's being provided another source of glucose and thus, blood glucose levels are more easily maintained. But, what if glucose ingestion during each bout of exercise interfers with gene expression that favors fat oxidation? Will this stunt muscle adaptations that ultimately lead to improved performance?

In steps Thorbjorn and colleagues from the University of Copenhagen, Denmark. They hypothesized that glucose ingestion during exercise would alter the gene expression of fatty acid transporters and enzymes. There results are published in the July 2009 issue of the Journal of Applied Physiology. To test their hypothesis, they asked 9 men to participant in a unique 10-week training program. To make each participant his own control, training consisted of 1-legged cycling. One leg was assigned the glucose trials and one leg was assigned the placebo trials. They trained one leg at a time on alternate days, 5 days per week. This meant each leg received on average 2.5 training sessions per week. They were given a 6% glucose solution (such as Gatorade) at a rate of 0.7 g/kg/hr during the glucose training sessions. Each participant performed a fatiguing test and performance was measured as length of time. The investigators also measured fat metabolism.

What they found:

• Training improved maximal power and time to fatigue, no difference between glucose and placebo
• Training increased fat oxidation during exercise, no difference between glucose and placebo

The investigator's hypothesis that glucose ingestion during training exercise would alter fat adaptations that normally occur with training was not supported by these results. Noteworthy is that training sessions did not differ between glucose and placebo, meaning each leg received the same training stimuli. This is good to know because it is possible that not ingesting glucose under certain circumstances would reduce training power output, thus reducing the training stimulus. Theoretically, because of this, not ingesting glucose could negatively affect training adaptations. But because there was no difference between trials in terms of training stimulus, this confounding effect seems to not be an issue here.

Bottomline: Keep drinking your Gatorade, your muscles will adapt just as well. And for athletes who train several hours daily, not consuming glucose during exercise will likely have a greater negative impact. Despite carbohydrate ingestion, athlete's muscles are trained to use more fat, which is one reason for their awesome endurance.

Reference: Thorbjorn et al. Glucose ingestion during endurance training does not alter adaptation. J. appl. Physiol. 106, 2009.

Quercetin: a magic bullet for ultradistance athletes?

Aerobic exercise causes oxidative stress. It's a natural occurence that results from by-products produced from oxidative processes that are necessary for aerobic metabolism. These by-products, sometimes referred to as "free radicals" or "reactive oxygen species" (ROS) are also created from the inflammatory responses to muscle injury resulting from prolonged, repetitive muscle activity. It's most evident in long distance runners whose muscles are activated eccentrically (producing force while being stretched, during the stepping phase of running).

The problem with ROS is that they are believed to instigate muscle injury and reduce immune function making some athletes more susceptible to infection. In fact, increased incidence of upper respiratory tract infection occurs in athletes during heavy training and competition. Those athletes who engage in prolonged intense exercise will experience a significant amount of oxidative stress, which can lead to muscle injury, increased fatigue and increased susceptibility to infection.

Bring on the antioxidants. Antioxidants, natural chemicals in the body, fight the ROS and do it quite effectively. There are many types of antioxidants but one type in particular is the group known as flavonols. Flavonols are thought to be anti-inflammatory, cardioprotective, anticarcinogenic and antioxidative. One flavonol getting more attention in endurance exercise research is quercetin, naturally found in foods such as onions, berries, red wine, broccoli, apples and tea. It's getting more attention as a supplement, often sold in a blend containing vitamin C (another antioxidant that enhances quercetins effects) and niacin (for it's blood flow enhancing capabilities). It is believe that quercetin supplementation can increase the body's antioxidant power and possibly reduce those negative effects from ROS. In fact, one group of investigators observed reduced upper respiratory tract infection among athletes consuming the supplement.

To test quercetin's effects on blood oxidative capacity in response to ultramarathon competition, Quindry et al from Appalachian State University in North Carolina tested several athletes competing in the 160-km Western States Endurance Race. Sixty three male and female athletes were recruited and placed into either a quercetin group or a placebo group. The study was a randomized and double-blinded. For three weeks, athletes in the treatment group consumed 1000 mg quercetin, 1000 mg vitamin C and 80 mg niacin daily. Blood was drawn prior to the race and during the first half hour following the race. The investigators tested the athletes for plasma antioxidant capacity, the first indication that quercetin is indeed decreassing exercise-induced oxidative stress.

What they found:

• Quercetin levels were 6.6-fold higher in the quercetin group compared to the placebo group
• Quercetin levels decreased significantly during the race in both groups
• Quercetin supplementation did not affect plasma antioxidant capacity
• Quercetin supplementation did not alter oxidative damage

Conclusion: this study did not find a protective effect from quercetin supplementation during ultramarathon running. So, is it worth the money to buy the supplements? Maybe, because some studies have noted positive effects.

Final word: Instead of supplements, why not get your quercetin from vegetables and fruits? A well balanced diet containing several daily servings of fruits and vegetables will more likely provide you all the antioxidant power (in addition to several other benefits) you require as an endurance athlete.

Reference: Quindry et al. Oral quercetin supplementation and blood oxidative capacity in response to ultramarathon competition. Int. J. Sport Nutr. Exerc. Metab. 18, 2008.

Want to improve performance? Rinse your mouth with Gatorade

Well known to endurance athletes are the benefits of carbohydrate during exercise lasting more than an hour. Ingesting the appropriate amount (the recommended amount is 40-60 g/hr, which is equivalent to 2/3-1 liter of Gatorade per hour) improves endurance performance. The effect of eating carbohydrate is to maintain optimal rates of carbohydrate use in the muscle, with or without sparing the glycogen stores. This becomes particularly important during the latter stages of endurance exercise when liver glycogen stores are too low to maintain blood glucose and avoiding hypoglycemia becomes difficult.

During exercise lasting 1 hour or less, the evidence for rationalizing carbohydrate ingestion is less clear. Some studies indicate that ingesting carbohydrate during this short period does indeed improve performance, while others have not observed this. Because of the lack of consensus, carbohydrate ingestion during periods of exercise lasting less than 1 hour has never been vigorously recommended.

Interestingly enough, there is some evidence that simply mouth rinsing with a carbohydrate drink improves performance, at least in cyclists. When given a carbohydrate drink just as a mouth rinse, some athletes began to feel better and were able to pick up the pace without having swallowed the carbohydrate. These results suggest that the brain may be monitoring the carbohydrate stores in the body. If the brain recognizes the carbohydrate in the mouth, it may be receiving signals that indicates an incoming energy source. In anticipation of its energy source, the brain may alter its response to exercise, resulting in a selected faster pace.

To further investigate this effect, Rollo and colleagues from Loughborough University in the UK tested carbohydrate mouth rinsing on runners during a 30-min treadmill run. These investigators did something alittle different from traditional performance studies. One way to test performance in the laboratory is to quantify power output or distance during a set amount of time and allow the athlete to adjust the pace accordingly. This is relatively easy to do with cyclists because the athlete simply has to increase or decrease his or her pedal rate to affect power output. But for runners on a treadmill, changing the running pace is less spontaneous and requires manual adjustment of the treadmill speed. To overcome this limitation, these investigators used an automated treadmill where the speed of the treadmill was automatically changed when the runner simply moved to the front or the back of the belt.

Ten endurance trained male runners each ran twice for 30 minutes, once with a placebo and once with a carbohydrate solution mouth rinse provided. The athletes were asked to run at a hard pace and were free to adjust the intensity at any time during the run. The mouth rinse was administered every 5 minutes in an amount of 25 milliliters (5 teaspoons). This study was a double blind (no one knew if the athlete was getting the placebo or carbohydrate solution until after the study was completed) and randomized (the order of the trials ) study.

The investigators found that the carbohydrate mouth rinse did:

• not affect heart rate or sweat rate response
• not affect rating of perceived activation
• improve feelings of "good" at the beginning of exercise, but not after that
• increase pace during the first 5 min resulting in overall improved performance (greater distance covered during the run)

From these results, it appears that simply rinsing your mouth with a carbohydrate solution has some positive effect on performance. The actual improvement in distance was approximately 1/10th of a mile (4.1 vs 4.0), on average. That's an increase in average running pace from 8.0 to 8.2 mph, certainly enough to give someone an advantage during a race.

Why did the benefits only occur at the beginning of exercise? Maybe the brain is too smart to be fooled more than once. If that is the case, the strategy of mouth rinsing may be beneficial only during short duration exercise (less than 1 hour). At least for runners who are prone to GI discomfort during races, a mouth rinse may be an alternative to not drinking anything, at least during 5k or 10k races. Anything longer than that, you are better off swallowing that carbohydrate solution.

Reference: Rollo et al. The influence of carbohydrate mouth rinse on self-selected speeds during a 30-min treadmill run. Int. J. Sport Nutr. Exerc. Metab. 18, 2008.

Rhodiola Rosea supplements for rowers

On my website, I wrote a review on a supplement called Optygen (http://cmierphotoandfitness.net/optygen.html), believed to improve endurance and recovery partially through the effects of antioxidants. It contains a blend of several ingredients including Rhodiola rosea extract, considered to be an antioxidant. At the time I wrote that, the only study I found that indicated a positive effect from any of the ingredients in Optygen showed that one dose of Rhodolia rosea increased aerobic capacity, but when taken over a 4-week period, had no further benefits. And a concurrent review article concluded that Rhodolia rosea’s effects are more promising as an antioxidant but not as a performance-enhancer.

Moving forward, a new study by a group of Polish investigators published in the International Journal of Sport Nutrition and Exercise Metabolism demonstrated improved antioxidant levels in the blood among competitive rowers following 4 weeks of Rhodiola rosea supplementation. The investigators randomly assigned 22 members of the Polish Rowing Team to either a placebo or 300 mg of Rhodiola rosea extract twice daily for 4 weeks. Before and after the supplementation period, the athletes performed a 2000-meter maximum test on a rowing ergometer. Blood samples were taken before, and 1 min and 24 hr after the exhaustive exercise. Samples were tested for total antioxidative capacity and markers for oxidative damage. And unlike so many studies in the area of supplementation and exercise, this study was a double-blind, random design. Thus, the results are solid.

The investigators reported the following: Rhodiola rosea did

• not result in improved performance
• increase total antioxidative capacity
• not reduce oxidative damage from intense exercise

It appears that taking Rhodiola rosea supplements with the intention of improving performance and reduce oxidative stress is unwarranted. There may be other antioxidants, such as quercetin that offer better results. For a review on antioxidant supplements, read my website article: http://cmierphotoandfitness.net/antioxidants.html.

Reference: Skarpanska-Stejnborn et al. The influence of supplementation with Rhodiola rosea L. extract on selected redox parameters in professional rower. Int. J Sport Nutr. Exerc. Metab. 19, 2009

Are you getting enough calcium?

A study published recently in the Journal of Bone and Mineral Research suggests that some athletes may be at risk of bone loss. We often think of exercise as being good for bones. Under most circumstances, exercise helps improve bone density and reduces the risk of osteoporosis. This is particularly so for weight-bearing activities such as running and weight lifting. However, during prolonged exercise, especially in the heat, a large amount of calcium can be lost through sweating. It is possible that athletes who engage frequently in prolonged vigorous exercise are at risk of losing bone. This is because bone acts like a reservoir for calcium and in fact, 99% of calcium in the body is found in bone. When fluid levels of calcium drop due to sweating, bone must offer up some of its calcium to help maintain homeostasis. Under such conditions, it seems it is more important for the body to maintain fluid levels of calcium than it is to maintain bone calcium. Calcium is important for cell function, nerve conduction and muscle contraction.

Drs Daniel Barry and Wendy Kohrt from the University of Colorado in Denver studied 14 male competitive road cyclists over a 1-yr period to determine whether or not bone loss occurred in these athletes. The investigators measured calcium loss through sweating during several cycling sessions and they measured bone density before and after the 12-month period. Here is what they found:

Bone mineral density decreased in the hip bones over a 9-mon competitive season with some recovery during a 3-mon post-competitive season.

Calcium loss during 2 hrs of cycling was estimated to be 135 mg.

Calcium loss was associated with bone mineral density. The greater the loss, the lower the density.

What does this mean to paddlers? Paddling, like cycling, is a weight-supported activity. In contrast, running is a weight-bearing activity. Athletes who engage primarily in weight-supported activities such as cycling, paddling or swimming may be at greater risk of bone loss than those athletes who engage in weight-bearing activities. In addition, paddlers who sweat heavily over prolonged periods are at an even greater risk. Despite sweating less, women can also be at risk because they generally have lower bone mineral content than men. Calcium supplementation may be necessary and it is possible that the RDA for calcium is inadequate for long distance paddlers.

My advice to you is to bone up on the types of supplements and calcium-rich foods that are out there and make sure you are getting adequate amounts. A good source of information on calcium can be found at the National Institute of Health's Office of Dietary Supplements website: http://ods.od.nih.gov/factsheets/calcium.asp

Reference:
Barry D. & W. Kohrt. BMD decreases over the course of a year in competitive male cyclists. J. Bone Mineral Res. Vol23, 2008.