Freelap Friday Five with Katie Mark
Katie Mark, MS, MPH, (On Your Mark Nutrition) lives in Miami, Florida, where she trains as a competitive cyclist and works as a sports nutritionist (including collaboration on nutrition science with SpikesOnly’s 12 2016 Olympic medalists), an R&D consultant, and a writer. Katie’s written works are nutrition-centered, evidence-based, and intended for those who are sport performance- or fitness-driven. She is skilled in investigating nutrition science research and applying the science in the real world. Her nutritional philosophy for optimal performance focuses on helping athletes achieve being fit and healthy by using nutritional strategies that target long-term training adaptations and long-term health. She holds a Master of Science in Nutrition Communication from Tufts University Friedman School of Nutrition and a Master of Public Health from Tufts School of Medicine. Katie will be a registered dietitian-nutritionist by early 2018. You can find her online at Katie Mark Nutrition and on LinkedIn.
Freelap USA: Can you get into some details about training the gut beyond simply taking a probiotic or performing trendy feeding strategies?
Katie Mark: Athletes need to think about their gut more often than just when they experience gastrointestinal (GI) problems. Athletes suffer from psychological and GI conditions, which are linked to the gut. The gut needs to function optimally because it can dictate your sport performance through energy provision (e.g., carbohydrate and fluid), immunity, defense against GI infections, cognition, brain function, and behavior. With this said, diet and strenuous training/competition heavily impact the gut.
The primary goal of the new nutritional strategy, “training the gut,” is to reduce GI symptoms and improve performance. This is done using multiple strategies that lead to adaptations in the gut that are critical to performance. For example, training with a relatively high carbohydrate intake during exercise can lead to adaptations in: 1) reducing bloating during exercise; 2) increasing gastric emptying; and 3) increasing the ability to absorb carbohydrate, which will increase the delivery of carbohydrate. The stronger your gut, the better your performance.Training the gut is important not just for performance, but also for health and longevity. Click To Tweet
Aside from a carbohydrate and fluid perspective, the gut microbiome is another lens to look through when training the gut. Research is showing the importance of the brain-gut axis, meaning that the gut microbiome influences our behavior, intestinal barrier, and immune function. Therefore, optimizing the gut microbiome for athletic performance (especially manipulation of the microbiome as a strategy for preparing for travel) is critical.
You’re right that it’s more than just taking a probiotic because diet can impact the gut microbiome. For example, circadian misalignment (e.g., jet lag) and the typical Western diet can change the microbiome composition (i.e., gut dysbiosis). Moreover, strenuous exercise weakens the one cell thick gut wall lining. This results in proteins in the gut lining loosening (which weakens your immunity) and bad things getting into your blood, which leads to acute or chronic inflammation (e.g., leaky gut) and/or metabolic dysfunction.
Training the gut is important not just for performance, but also for health and longevity.
Freelap USA: Watermelon, like many fruits and vegetables, doesn’t have any significant levels of salt and is growing in popularity. Should the average athlete doing typical single sessions of training worry much about getting enough salt in their alternative sports drink?
Katie Mark: Definitely not. If you’re eating normally, then there’s no reason to worry about getting enough salt from your sports drinks. First and foremost, sports drinks require context when considering using them because they’re pretty much just sugar water. The main reason for drinking a sports drink comes down to the intensity and duration of the exercise. But, I also consider the athlete’s goals for health and training adaptations (e.g., improving metabolic efficiency), which is an entirely larger topic that’s out of the scope of this interview.
As for the argument that you need to get salt, this is a tough one because how much salt does an athlete need? Again, this comes back to context. Sweat rate is determined by the density of active sweat glands multiplied by the secretion rate per gland. Salt from sweat is highly variable within an athlete as well as among different athletes. The variability within an athlete and among athletes in sweat rate is because of differences in sweat secretion rate per gland instead of the total number of active sweat glands or sweat gland density. There are so many factors that impact how much sweat you lose, including: day-to-day variability; environmental conditions; clothing/equipment; hydration status; body mass; menstrual cycle; and genetics.
Yes, salt is important to replace if you’re losing a lot of sweat and/or you’re a salty sweater, but much of the time athletes aren’t exclusively using sports drinks. Athletes sometimes forget they’re also consuming food before or during exercise. There’s obviously no shortage of salt in the American diet, either.
Athletes get bombarded with all different pieces of advice, but they need to remember the powerful influence of marketing. Despite what the sports drink industry says, it’s very difficult for there to be the “perfect” sports drink with respect to sodium content.
Freelap USA: Hydration is getting a lot of attention now as the research shows that aerobic endurance isn’t as impaired from loss of sweat. Cramping from electrolyte and water loss is losing momentum. On the other hand, maximal neuromuscular performance seems to be more sensitive. What is a good strategy beyond “drink if you are thirsty?”
Katie Mark: The dehydration and electrolyte imbalance (e.g., sodium) theory is one of the main theories behind exercise-associated muscle cramps (EAMC). The science is still unclear as to what exactly causes an EAMC. It may even be multifactorial. The dehydration/electrolyte imbalance theory, however, has been driven mostly by case studies and observational research studies with some limitations in their methodology, as well as by the sports drink industry.
Recently, the strongest evidence shows that EAMC has a neuromuscular etiology. In other words, the pain, stiffness, and bulging muscle are most likely due to neuromuscular fatigue. Studies have shown no differences in hydration status or electrolyte levels between cramp-prone and non-cramp-prone individuals. Athletes have also experienced an EAMC when they’re completely hydrated and have adequately supplemented with electrolytes.
Let’s consider an important observation: What is the first thing an athlete does when they get a cramp? Obviously, they may fall to the ground. But then they stretch the muscle. This static stretching usually relieves the cramp. Stretching is a known immediate treatment for EAMC, which makes the electrolyte/hydration theory questionable because, needless to say, stretching does not impact electrolyte imbalance or hydration.
This stretching activates the Golgi Tendon Organs (GTOs), which work with muscle spindles to regulate muscle stiffness. The first step in EAMC is muscle fatigue due to overloading skeletal muscle. The local muscle fatigue causes an increase in the activity of the muscle spindles (excitatory) and a decrease in the activity of the GTOs (inhibitory). This imbalance causes more of an excitatory drive to the alpha motor neurons in the spinal cord. The overexcited motor neurons then produce the cramp.
This doesn’t mean that fluid and electrolyte balance isn’t important. It’s just part of a holistic nutrition plan that is not one-size-fits all. It is suggested that EAMC may occur when various factors, such as poor conditioning, muscle damage, and fatigue, come together and cause the over-excitation of the motor neurons.
Even though muscle fatigue is not completely clear, this has led to a new area of sports nutrition called, “Neuro Muscular Performance” (i.e., nerves and muscle cooperatively working together), which focuses on neuromuscular training. Nutritionally, there is a particular blend of spices that targets receptors found in sensory nerves called Transient Receptor Potential (TRP) ion channels, which are found in the mouth, esophagus, and stomach. These TRP receptors connect to the brain and communicate to other parts of the nervous system, which includes the nerves in the spinal cord that communicate with skeletal muscle. TRPs are activated by a certain blend of strong spices. Research has shown that activation of the TRP receptors sends nerve signals to the spinal cord that tell the spinal nerves to send “calming” impulses at the skeletal muscle. This re-stabilizes the over-firing nerves and stops the cramp.
Essentially, a good strategy is to focus on neuromuscular training, especially by replicating “race pace” during training.
Freelap USA: Tart cherry has a lot of fans now, but old concerns about blunting adaptations also have an argument for periodizing the use of recovery drinks. What are your thoughts here?
Katie Mark: Context is important in this decision. Antioxidants can blunt training adaptations, but can enhance short-term performance. If the athlete believes optimal recovery time is more important (e.g., competition) than training adaptations, then drinking tart cherry juice (for the antioxidants) would be an effective short-term strategy in enhancing recovery from exercise-induced inflammation, muscle soreness, and oxidative stress. However, it must be the right type of tart cherry (e.g., Montmorency), the effective dosage, and consumed for a certain time period (i.e., drinking tart cherry juice right after a hard workout is not going to be as effective as drinking it seven days leading up to the hard workout). Also, it used to be that inflammation was bad for recovery from exercise, but now it’s accepted that inflammatory responses are important for muscle repair and regeneration.
If you’re in your hardest training cycle (e.g., strength and conditioning with lots of eccentric muscle actions), then go ahead and implement it in your nutrition plan for that cycle. If you’re on your taper week, then you probably don’t need it, and your plan for recovery drinks should change. Tart cherry juice can help with the pain if you’re going to do strenuous exercise, but if you’re not, then re-strategize your recovery drink. Also consider that tart cherry juice does contain a high amount of sugar. So if you’re going to drink it, consider your training demands. This is a perfect example of nutrition periodization tailored to training periodization.
Freelap USA: Caffeine is a timeless supplement and is the No. 1 drug in the world. With research on the brain and nutrition growing, what are the new frontiers in this space?
Katie Mark: Sports nutrition is getting bigger and more exciting than just “fueling,” which has many outdated recommendations. For athletes, nutritional training is becoming just as important as actual training. Research is investigating how nutrition impacts training, adaptation, and preparation, and especially how athletes adapt and recover from different training circumstances. We’re starting to see that it’s not high carb versus high fat for optimal performance, but rather a manipulation of the two macronutrients through nutrition periodization.
Nutrition advice for athletes is also getting more personalized, due to the high variability between athletes (e.g., responders vs. non-responders in beetroot juice supplementation). Also, the concept of fit versus healthy is gaining traction as the two are not synonymous. Many athletes are fit, but unhealthy due to their diet (e.g., six-pack abs and prediabetic fasting glucose levels).For athletes, nutritional training is becoming just as important as actual training. Click To Tweet
Training adaptations have focused on skeletal muscle, but now the science is looking at how the brain and GI tract can also adapt to enhance athletic performance. Research is further investigating the relationship between stress from exercise, the gut-microbiota-brain axis, and dietary practices. Demands from intense exercise yield a stress response, including fatigue and mood disruptions, which activates the sympathetic-adrenomedullary and hypothalamus-pituitary-adrenal (HPA) axes. This releases stress and catabolic hormones, as well as inflammatory messengers. The gut microbiome is at the intersection of this brain-gut axis. Therefore, research is now looking at targeting the gut therapeutically via the athlete’s diet, with the goal of taking better control of the brain-gut axis and, ultimately, hacking enhanced performance.
Furthermore, research in neurological health is exploring the cognitive effects of certain foods, and specifically foods high in polyphenols. Diet and exercise can impact how quickly our memory declines with aging. Antioxidant consumption is suggested to be related to maintaining cognitive function. Fruits have plenty of different antioxidants, yet there are large variations in antioxidant capacity among different fruits. Polyphenols in pomegranate fruits have the highest antioxidant capacity of fruit juices and have shown neuroprotective effects. This is a perfect example of the importance of people focusing less on carbs, protein, fat, and calories in their diet and more toward specific foods that are “functional” and extend our longevity.
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