For athletes, caffeine is more than just a morning pick-me-up. Strategically adding caffeine to your nutrition plan before and during exercise can help keep your mind sharp, decrease perceived effort, boost your endurance, and delay fatigue.
Mental benefits:
Physical benefits:
Okay… But How Much & When?
The short answer is that consuming caffeine both before and during exercise has benefits. More is not necessarily better. Research suggests that even a small amount of caffeine (70 mg) during exercise can improve performance.
Up to 400 mg of caffeine per day is considered safe. However, caffeine stays in your system even during exercise, so consider skipping the extra caffeine for your evening activities to avoid disrupting your sleep!
GU uses naturally derived caffeine from green tea leaves.
But, before we dive into her results, here’s some background on what metabolic efficiency means.
Metabolic flexibility can be described as the ability to utilize fat and
carbohydrate fuels,and to transition between them in response to changes in dietary intake or circulating levels of each in the blood.
Metabolic efficiency refers to the body’s ability to utilize its on-board (non-supplemental) stores of carbohydrate (glycogen) and fat more efficiently during rest and across different intensities of exercise. It’s essentially the ability to preserve glycogen and burn fat as fuel.
Main difference between the two: Just because you can doesn’t mean you’re good at it. Metabolic efficiency means you’re a pro at managing fuel sources. Like a hybrid car.
We want our athletes to be really good at preserving their limited glycogen stores, thereby delaying fatigue and extending endurance performance. Being metabolically efficient also makes you more “bonk-proof” in the face of sub-optimal nutrition intake. Because, let’s face it, you aren’t going to replace every calorie you burn while you’re exercising.
What you eat and how you train (and what you eat while you train) can profoundly impact your ability to use your own body fat as a fuel source. 75% of this is nutrition, 25% is training. In our lab, we try to get our athletes to become more metabolically efficient by using nutrition interventions primarily and training secondarily (e.g., fasted training, train low/compete high).
What have you learned from testing your metabolic efficiency?
I learned that I burn fat up to a very high level of exercise intensity. We didn't find a crossover point during the test even though I got very close to VO2 max. I am very efficient at utilizing fat during exercise and I think that serves me very well during Ultra distance events.
How did you (or your coach) apply the results to your training?
Since I am training for a marathon, I wanted to train my body to use more carbohydrates during higher intensity running. I have been incorporating more Energy Gels and ROCTANE Energy Drink Mix in my training runs.
Did you make any other lifestyle (example: nutritional) changes?
I have not made any major nutritional changes, though I do try to eat a better breakfast pre-run.
What surprised you (if anything) about performing the test itself and/or the results?
I was surprised that I never reached a crossover point during the test. I assumed that every person would eventually primarily use carbs as fuel at a high enough intensity.
What’s the biggest nutritional change you have made since the test and in preparation for the trials?
I think the biggest nutritional change I have made is to take in more carbohydrate calories during training runs, even easy runs.
]]>For athletes, caffeine is more than just a morning pick-me-up. Strategically adding caffeine to your nutrition plan before and during exercise can help keep your mind sharp, decrease perceived effort, boost your endurance, and delay fatigue.
Mental benefits: The mind is a powerful muscle when it comes to endurance sports performance!
Physical benefits: It’s not just in your head…
Okay… But How Much & When?
The short answer is that consuming caffeine both before and during exercise has benefits. More is not necessarily better. Research suggests that even a small amount of caffeine (70 mg) during exercise can improve performance.
Up to 400 mg of caffeine per day is considered safe.* However, caffeine stays in your system even during exercise, so consider skipping the extra caffeine for your evening activities to avoid disrupting your sleep!
Cold Brew Coffee ROCTANE Energy Gel packs in 70mg of caffeine (which is double the amount in other caffeinated ROCTANE Energy Gels) along with the electrolytes and amino acids delivered by all ROCTANE Energy Gels.*
*Do not exceed 5 servings of Cold Brew Coffee ROCTANE Energy Gel daily. Not recommended for pregnant or nursing women, children under 18 years of age, or people sensitive to caffeine.
]]>Some of our vegan-friendly products are manufactured in facilities that share equipment with other non-vegan ingredients. We want to let you know, so you can make the best decision according to your own dietary preference.
In 2015, one of our employees and long-time plant powered athlete posed a question, “why aren’t our Energy Gels vegan?” This question prompted our R&D team to take a closer look at our ingredients, specifically amino acids, which are critical components of our products. One essential amino acid, leucine, is responsible for initiating protein synthesis, the process through which your muscles rebuild and get stronger. There are both plant-sourced and animal-sourced leucine, and many products use the more accessible animal-sourced leucine.
However, our R&D team wasn’t willing to sacrifice quality for convenience, so they worked tirelessly to create a fast dissolving plant-extracted leucine. Now, we can add leucine and make vegan products without compromising performance!
To learn more about the different vocabulary associated with our products, check out our Nutrition Lab glossary here!
We are proud to support plant-powered athletes like pro mountain biker Sonya Looney! To read more about her philosophy on nutrition and fueling, check out her training, racing and nutrition plan.
Did you know that all of our product wrappers are recyclable? To keep our trash out of landfills (and off of our trails), we’ve made it easy to collect your used packets and upcycle them into to items like Adirondack chairs and bicycle racks. To learn more about our recycling program, check out our partnership with TerraCycle, join our brigade, and get involved!
But what causes this sensation? While there are many biochemical systems in our body that regulate mood, the opioid and endocannabinoid systems are believed to be the main players in the runner’s high experience. However, there’s a debate in the sports-science community as to which system is the primary cause. An added challenge of investigating the runner’s high is that the feeling is subjective. Each runner experiences his or her own “runner’s high,” and scientists must rely on correlations between subjective descriptions and changes in physiological activity.
The Anti-Stress Molecules
When the body is placed under stress from exercise, it has internal mechanisms to cope with and prevent damage. Running triggers messages sent by brain neurons to tell the body something needs to be done to control the stressful stimuli. Neurons and neuronal networks, much like telephone wires, carry messages across the body to different locations, initiating the production of messenger molecules which bind to specific receptors in a lock-and-key fashion. When the receptor is “unlocked” by its designated molecule, chemical reactions occur. It’s these chemical reactions that induce feelings of analgesia, euphoria, and overall positive mood shifts – also known as the runner’s high.
Scientists have proposed two hypotheses to explain why these chemical reactions lead to the runner’s high phenomena.
The Endorphin Hypothesis
“Exercise gives you endorphins. Endorphins make you happy. Happy people don’t shoot their husbands.” – Elle Woods, Legally Blonde.
Scientists initially attributed runner’s high to the Endogenous Opioid system, which is responsible for pain, stress-management, and reward. You may recognize the word “opioid” in association with drugs like morphine and heroin. When the body experiences stressful stimuli (as when running), it sends messages through the nervous system to produce narcotic-like substances, one such being β-endorphin.
β-endorphins are often credited as the source of that happy, glowing sensation common after sustained physical activity. This theory first surfaced in the 1980’s, when scientific research looked at endogenous opioid production in runners during physical activity. Scientists found that running for prolonged periods increased levels of β-endorphins in the body’s circulation. This increase was correlated with increased reports of positive mood changes. The correlation led researchers to conclude that β-endorphins produce the runner’s high.
The Problem with the Endorphin Hypothesis
Since the 1980s, further research has identified glaring flaws with this hypothesis:
While the endorphins have not been completely discredited for producing the runner’s high, scientists are now proposing that other molecular system also play a role.
The Endocannabinoid Hypothesis
Endocannabinoids are molecules naturally produced in the body that have the same chemical structure and bind to the same receptors as THC (the molecule in marijuana). The endocannabinoid system has similar pain regulating, mood alerting properties as endogenous opioids (see above). The two molecules produced in this system are Anandamide and 2-AG, and they are both produced in the brain and peripherally.
Why the Endocannabinoid Hypothesis is more plausible
Summary
While endorphins are often credited with producing that euphoric post-run feeling known as the runner’s high, recent research has identified many flaws in this hypothesis. A different class of molecules, called endocannabinoids, is now being considered as the primary cause of the runner’s high. Even though the scientific community may not have a definite explanation, we can all agree that exercise makes us feel great. Our verdict: Go lace up those shoes and experience the high for yourself!
Resources
Boecker, H., Sprenger, T., Spilker, M. E., Henriksen, G., Koppenhoefer, M., Wagner, K. J., … & Tolle, T. R. (2008). The runner’s high: opioidergic mechanisms in the human brain. Cerebral Cortex, 18(11), 2523-2531.
Dietrich, A., & McDaniel, W. F. (2004). Endocannabinoids and exercise. British Journal of Sports Medicine, 38(5), 536-541.
Dishman, R. K., & O’Connor, P. J. (2009). Lessons in exercise neurobiology: the case of endorphins. Mental Health and Physical Activity, 2(1), 4-9.
Fuss, J., Steinle, J., Bindila, L., Auer, M. K., Kirchherr, H., Lutz, B., & Gass, P. (2015). A runner’s high depends on cannabinoid receptors in mice. Proceedings of the National Academy of Sciences, 112(42), 13105-13108.
Goldfarb, A. H., & Jamurtas, A. Z. (1997). β-Endorphin response to exercise. Sports Medicine, 24(1), 8-16.
Markoff, R. A., Ryan, P. A. U. L., & Young, T. (1982). Endorphins and mood changes in long-distance running. Medicine & Science in Sports & Exercise, 14(1), 11-15.
Raglin, J. S. (1990). Exercise and mental health. Sports Medicine, 9(6), 323-329.
Sparling, P. B., Giuffrida, A., Piomelli, D., Rosskopf, L., & Dietrich, A. (2003). Exercise activates the endocannabinoid system. Neuroreport, 14(17), 2209-2211.
]]>All this talk of HRV got your heart racing? Check out the following guest article by Marco Altini, PhD, Data scientist, Entrepreneur | Full bio below
Heart rate variability (HRV) is an important marker of an individual’s physiological stress level. In particular in the context of training, intense exercise is a strong stressor, therefore leading to higher physiological stress, which can be captured with HRV, for example in the form of acute drops post high intensity activity, which can last for up to 48 hours post-exercise. This is part of the rationale behind measuring HRV to better understand our body’s response to training and optimize recovery. By combining HRV with other parameters and contextual information related to lifestyle and training, we can better understand the big picture, see how an athlete is adapting (or not adapting) to a specific training block, and try to make changes to avoid overtraining, eventually leading to better performance.
Due to recent technological improvements in terms of computation power and accessibility to high quality wearable technology we are seeing all sorts of applications making use of HRV today, from optimizing performance in sports, to monitoring psychological stress in the workplace.
While HRV is a powerful tool and can be very helpful in better understanding physiological responses to both acute and chronic stressors, interpreting HRV data at the individual level can be challenging. This article focuses on practical ways to acquire and interpret HRV data in the context of monitoring training load and optimizing performance, using HRV4Training as an example.
Practically speaking, our heart does not beat at a constant frequency. So even if we measure our pulse, and get a 60 beats per minute reading, it doesn’t mean we have a beat every second. The time differences between beats are slightly different, they can be 0.9 seconds, 1.2 seconds, and so on. When we talk about HRV, we talk about ways to quantify this variation between heart beats.
This explains also why HRV, is not a single number, and there is sometimes a bit of confusion on different metrics to measure HRV since we can quantify these beat to beat differences in different ways. However, especially in the context of using HRV to monitor physiological stress, the community settled on one specific feature which is called rMSSD. It’s a time domain feature, easy to compute. So most commercial tools or apps, will provide you with either rMSSD or with a transformation of rMSSD to make the value a bit easier to interpret, for example scaling it between approximately 1 and 10 or 1 and 100. This is also what HRV4Training does, when providing what I called Recovery Points.
Let’s take a step back and talk a bit about the autonomic nervous system. The autonomic nervous system regulates many body functions, mainly unconsciously, such as respiration, the heart beating and so on, and consists of two branches, the sympathetic and parasympathetic branches.
The sympathetic branch, is in charge of the fight or flight response, while the parasympathetic branch promotes a rest and recovery. Making a few simplifications, since the autonomic nervous system maintains an adaptive state of balance in our body, we can better understand how we react to different stressors, by analyzing autonomic function.
This means we would expect higher parasympathetic activity under conditions of rest, when we are well recovered and rested. Since the autonomic system regulates the heart beating, we can use HRV as a proxy to autonomic function, and therefore use HRV as a way to measure how we react to stressors. This is where collecting HRV data can become very interesting, because we can, for example, start to figure out how much time our body needs to get back to normal after an intense workout or spot the early onset of a flu, as well as understand how our body is reacting to big stressors like intercontinental travel or other life situations.
Up to a few years ago, HRV was used mainly by academic researchers working at the intersection of sport, health and medicine. Many of these experts were able to show links between HRV and performance as well as recovery or training load and chronic disease.
However, in the recent past many new, affordable and user-friendly tools have been developed. These tools typically rely on commercially available heart rate monitors (e.g. a Polar chest strap) to analyze data, compute HRV and provide guidance to the user. Most of these apps rely on spot measurements of about 1 minute.
The latest developments go even a step further in terms of usability and accessibility. With apps likeHRV4Training, HRV can be computed accurately without the need for any external sensor or device. The main advantage is the increased compliance and reduced cost. The techniques used by HRV4Training have also been validated, showing equivalency with not only a chest strap but also electrocardiography in the context of measuring heart rate and heart rate variability. (Reference)
HRV4Training screenshots
HRV4Training uses the phone camera to extract photoplethysmography (PPG, basically blood flow from the finger) and then determine markers of the autonomous nervous system activity, in particular parasympathetic activity. Regardless of the tool you decide to use, make sure the technology is reliable. For example, there are many optical watches out there, but almost all of them as of 2017 can only provide reliable HR, and not HRV, due to much averaging performed to stabilize the signal. (Read: Is there any wristband activity tracker that tracks HRV reliably enough?)
By quantifying parasympathetic activity, HRV4Training and other apps are able to translate HRV information into an assessment of stress level and provide actionable insights, helping users to better understand how their body responds to life stressors and other factors (e.g. sleep, stress, disease, etc.).
However, taking advantage of the data is not that simple. We need to take care of a few extra steps to make sure the information we are collecting is reliable.
Clinical studies were carried out under very specific, strict, laboratory conditions. Typically, this meant showing up at a lab early in the morning, measuring 2 hours after a light breakfast and at rest, a pre-measurement period including up to 30 minutes lying down in the lab, and so on. Even with the right tools, HRV can be difficult to gather under similar conditions when measured in the wild, and these difficulties can make interpretation harder.
Additionally, research showed that many factors influence HRV, from body posture to respiration, age, genetics, gender, physical exercise, chronic health conditions and more. So how can we get reliable insights from HRV data, if it is affected by so many factors?
First, we need to look only at measurements with respect to ourselves, which means that as we collect more data and understand what are normal values in your specific case, we can start looking at how much you deviate from your normal on a given day, and provide tailored advice that can help in making adjustments to our days. Additionally, our baseline HRV can improve over time with practices such as aerobic exercise and meditation.
Secondly, we also need to control for as many of the previous factors as we can, and then evaluate the effect of what we care about. Apps like HRV4Training provide a set of simple rules (or best practices) so that the measurements your take at home are as close as possible to supervised laboratory recordings, and your data is more reliable.
Take the measurement first thing after waking up, possibly while still in bed. This way you have consistent time of the day, and you are not affected by other stressors. When you take the measurement, it’s very important to try to relax, and not to think about other factors that might be stressing you out, like what’s coming up during the day. Lying down, sitting or standing are all good positions, again what matters is consistency. If you decide to stand, it’s very important to be patient, and wait a minute or two before starting the measurement, since your body needs to be at complete rest and measuring too early after standing up might cause the measurement to be affected. Most apps make following best practices easy for you by providing 60 seconds measurements and suggesting a morning measurement as part of your routine.
While certain physiological responses to training have been shown consistently across broad populations (for example reduced HRV after more intense workouts) each individual is different and experiences stress differently. In particular, for recreational athletes, many other stressors might be present in life, such as a demanding job or a newborn in the family. Collecting data for several weeks before implementing changes will help better understand how we react to such stressors and consequently figure out when to take it easy, avoiding additional stress, and when to push it in our workouts.
While one of the main advantages of using HRV4Training is the ease of use and the ability of acquiring data without the need for external hardware, most of our work today is focused in helping users interpreting their physiological data. We do so by providing different advanced Insights that are enabled in the app as soon as enough data is available. In particular, as physiology is affected by almost anything that happens in our lives, context is key. Using the app, you can enrich physiological measurement with contextual information collected either automatically (training data from Strava, TrainingPeaks or SportTracks, weather and altitude data from OpenWeatherMap, etc.) or manually (anything from additional training variables, lifestyle, subjective scores, notes, as well as custom tags), and then explore the relation between these variables, for example using Correlations (linear relation between two variables over time) or the Acute Changes Analysis (day to day changes in response to a specific stressor, for example, are there consistent physiological changes due to travel?). Other insights are specifically designed around training, for example workouts data is used to estimate cardiorespiratory fitness (VO2max) based on submaximal heart rate during exercise (simply put, the lower your heart rate at a given intensity, the more fit you are), or the Polarized Training analysis which helps you figure out how much of your training is done at low intensities (this approach is known in pop culture as 80:20). Similarly, HRV4Training provides a Training Load Analysis where both injury risk and freshness can be analyzed. Finally, multi parameter physiological data is analyzed over longer periods of time in the HRV Trends insight, to provide users with a view that is not only focused on day to day changes in response to a specific training, but also on the longer term adaptation to a given training block, in terms of positive adaptations, maladaptation to training, and so on. As you use the app and collect data, patterns will start to arise in response to the specifics of your lifestyle and training regime, and having an objective measurement of your body’s response to these stressors can be helpful in making adjustments and striking the right balance between lifestyle, training and recovery, eventually leading to better performance.
To learn more, visit HRV4Training’s blog: www.hrv4training.com/blog or website: hrv4training.com.
Author Marco Altini holds a PhD in applied machine learning (cum laude) and MSc in computer science engineering (cum laude). He is currently leading data science activities at Bloomlife, a digital health startup using wearable technology and data analytics to improve prenatal healthcare. Marco is also the creator of HRV4Training, a mobile platform enabling physiological measurements without the need for external sensors.
]]>The short answer is yes!
While we know food is fuel, the reality is that our digestive tracts can only absorb so many nutrients at once. If you overload your system, you will likely end up with GI issues like nausea, bloating, cramps…or worse!
We recommend starting with 150-200 calories per hour of activity for races or training sessions over 60-90 minutes.
It’s possible to train your body to absorb more calories, and some people can tolerate up to 400 calories per hour. More calories in means more energy to burn and less reliance on stored carbs (glycogen).
To train your gut to absorb more calories, start out at 200 calories per hour during a long run or ride and add 25-50 calories per hour on successive long training sessions to assess your tolerance. (Note – training your gut to absorb more than 250 calories per hour is important for events lasting longer than 2.5 hours. For events under 2.5 hours, you can afford to rely more heavily on your body’s glycogen stores.)
Carbohydrate are the easiest energy to absorb and metabolize during endurance activities or high-intensity exercise. When you exercise, blood flow to your viscera (i.e., stomach, digestive tract) is redirected to your muscles to provide sufficient oxygen for muscular contractions. Reduced blood flow means reduced ability to digest and absorb nutrients. It’s not surprising that half of endurance athletes encounter GI issues during exercise!
1) Hydrate Early and Often: Don’t wait until the morning of your race to start your hydration plan!
2) Sip and Nibble: Think of your fueling strategy like an IV drip.
The goal is to take in calories and fluids in small, frequent doses rather than as large quantities spread out every hour or so. Try to eat or drink something every 15-20 minutes, however small it may be! An Energy Chew or two, a sip of or Roctane Energy Drink Mix, something to keep a steady flow of nutrients and energy to your working muscles. (Pro tip: set an alert on your watch to help keep you on track!) The “trickle feed” method will also reduce the likelihood of having GI issues on race day, which means no more emergency trips to the porta-John!
3) Train Your Nutrition: However you chose to fuel on race day, be sure to practice, practice, practice!
Race day is not the time to try anything new. Your nutrition plan should be dialed, even down to which flavors you know work well during long runs. It’s particularly important to find out how much fluid you can tolerate before you get that sloshing feeling in your stomach. (Hint: if you get sloshy-stomach, you’re probably drinking too much!) Practice your plan during weekly long runs leading up to your race, and adjust as needed. A good starting goal is to consume 200-400 calories per hour for runs longer than about 90 minutes. Remember, calories come in many shapes and sizes: gels, chews, stroopwafels, and even drink mixes. Mix up the flavors to find the ones you absolutely love!
4) Protect Your Muscles: During prolonged, strenuous exercise (like marathons!) your body will start to break down its own muscles to supply amino acids for energy production.
To protect your muscles from breakdown and help kick start recovery, we recommend supplementing your supply of branched-chain amino acids (BCAAs), which are the most important amino acids for muscle repair and rebuilding. Not only that, BCAAs are metabolized directly by the muscles themselves, providing an additional energy source! (Read six reasons to take BCAA Capsules today.)
Tip: take four Roctane BCAA Capsules before and four BCAA Capsules after your race to minimize muscle breakdown, promote recovery, and help you avoid having to walk like the Tin Man after your race.
5) Don’t Wait Until the Last Minute: While it’s tempting to go for the all-you-can-eat pasta dinner the night before your race, this might not be the best strategy.
Chances are, you’ll end up overeating on foods you’re unaccustomed to digesting and regret it later. Instead, try upping your carbohydrate intake 2-3 days leading into your event, while also cutting back on fat and fiber. Along with your taper (you ARE tapering, right?), this strategy will effectively stock your muscle and liver glycogen stores (a.k.a., fuel tanks) without leaving you feeling bloated and uncomfortable the night before the race.
While we think it’s important to have a plan, we also know that everything doesn’t always go according to that plan on race day. You might not be able to find your favorite oatmeal brand for breakfast, you could lose a gel in the chaos of the start, or even miss an aid station. So, if something goes awry, stay calm, smile, and remember that running is fun!
]]>Here at GU, we believe that our thirst is not always a reliable way to gauge proper hydration during exercise, and we found a recent study that advocates for drinking early and often to achieve optimal performance.
You can find the abstract here, but the cyclists in the study who followed a prescribed hydration plan saw the following benefits:
In short, drinking according to a plan resulted in higher cycling speeds, greater power output, and a faster finish time. We like the sound of that!
When you lose body fluids during exercise (through sweat, respiration, etc.), your blood plasma volume decreases. Thicker blood is harder for the heart to pump, which leads to two things: reduced blood flow to your working muscles and less heat released through your skin. Dehydration can result in lower cardiac output, less blood flow to your skin, and decreased sweat production, all of which contribute to a rise in core body temperature!
As you might guess, exercising in the heat exacerbates dehydration, which puts even more strain on your body. Hotter temperatures can even shift your body’s fuel preference to burn more carbohydrates, leading to early fatigue if muscle glycogen stores become depleted.
These negative effects can be triggered by as little as 1-2% body weight loss! To make matters worse, exercise also feels harder when you’re dehydrated, as cognition and mood can be negatively affected by even a modest amount of dehydration.
Here’s an easy trick to determine whether or not you are drinking enough by calculating your sweat rate is:
One obvious factor that could promote dehydration during exercise in the winter has do to with overdressing for conditions. Exercising in the cold with too much or the wrong type of clothing can lead to increased thermal stress. This hot microclimate around the body can result in excessive sweating and overheating to levels similar to exercise in the heat. Therefore, it is important to dress appropriately.
Exercise in the cold is also different than exercise in the heat in a few subtle and less appreciated ways that can impact hydration status. Below is a discussion of a few differences between exercise in cold vs. temperate environments that every athlete should know.
Many times when individuals exercise in the cold for winter sports, it is at a higher altitude than normal. Relative to exercise at sea level, the same exercise at altitude results in increased ventilation to maintain blood oxygenation. Increased ventilation promotes dehydration because our breath is saturated with water, and so increased breathing results in increased water loss. Physiologists call this “insensible” water loss, as it is out of our control. This route of dehydration is usually chronic (since ventilation is also increased at rest at altitude) and can really add up without an individual perceiving that any water has been lost!
One important factor to consider when exercising in the cold is that our bodies have a decreased perception of thirst when in cold environments. This has been shown in animal studies where exposure to cold air at 5°C during rest for a period of time resulted in decreased water intake and increased evaporative water loss relative to animals at room temperature. When the animals were moved to room temperature of 26°C, they began drinking water within 15 min which lasted for about 1 hour (1). Similar studies showing less water intake during rest and exercise in the cold have been performed in humans as well (2). When individuals exercised in the cold in either a hydrated or dehydrated state, the perception of thirst was always blunted by close to 40% in the cold compared to a thermal neutral environment (3, 4). Therefore, individuals exercising in the cold are going to be predisposed to dehydration due to decreased perception of thirst! Therefore, athletes exercising in the cold need to be extra vigilant to maintain good hydration habits.
Other than the decrease in thirst in the cold, there is also an alteration in the brain’s perception of dehydration in the cold. This effect can be explained in part by the redistribution of blood volume. To maintain core temperature in the cold, our bodies constrict blood from the periphery (arms, legs, and skin) to maintain the warm blood around the core of our body. This is called vasoconstriction, and this tricks our brain (the hypothalamus actually) to thinking our bodies have plenty of blood volume – even though dehydration is a common finding in the cold. Normally when we are dehydrated, plasma arginine vasopressin (AVP – also known as anti-diuretic hormone) increases to minimize kidney urine production to reduce urinary water loss and help maintain blood volume. In the cold, despite dehydration, central blood volume shifts prevent the increase in plasma AVP relative to the same amount of dehydration in a warm environment (3). This results in increased urine production, promoting dehydration. Interestingly, there is a strong relationship between plasma AVP and thirst, which means that part of decreased thirst in the cold may be attributed to lower concentrations of plasma AVP. Therefore, athletes exercising in the cold often have increased urine production compared to a more temperate environment. These changes result in an increased risk of dehydration in the cold that are not always obvious.
There are no consistent differences in exercise fuel utilization during exercise in the cold compared to exercise at the same relative intensity in a warm or hot environment. Some reports suggest mobilization of fatty acids from adipose tissue is decreased in the cold (perhaps due to constricting blood flow to adipose tissue), but this does not change working muscle substrate use. Similarly, there are no consistent changes in blood glucose or glycogen degradation during exercise in the cold (5). Interestingly, there are some data suggesting that exercise in the cold with cold muscles can decrease maximum voluntary force and promote fatigue (6). Some of this may be due to an increased use of fast twitch muscle fibers in the cold (7), which would be less fatigue resistant, and may also explain the increase blood lactate concentration often found during exercise in the cold (8). So other than a decrease in muscle strength and increased fatigue when exercising with cold muscles, there are few metabolic alterations that need to be considered during exercise in the cold.
Other than dressing properly to not over- or under-heat, athletes need to be aware they will have increased water loss and decreased thirst while exercising in the cold. All the same principles for maximal exercise performance exist in both cold and warm environments. These principles include making sure to start exercise in a hydrated state, and consuming enough fluids during exercise to prevent dehydration and the decrease in performance it brings.
Post by By Bryan Bergman, PhD and Brent Mann
1. Fregly MJ 1982 Thermogenic drinking: mediation by osmoreceptor and angiotensin II pathways. Fed Proc 41:2515-2519
2. Sagawa S, Miki K, Tajima F, Tanaka H, Choi JK, Keil LC, Shiraki K, Greenleaf JE 1992 Effect of dehydration on thirst and drinking during immersion in men. Journal of applied physiology 72:128-134
3. Kenefick RW, Hazzard MP, Mahood NV, Castellani JW 2004 Thirst sensations and AVP responses at rest and during exercise-cold exposure. Medicine and science in sports and exercise 36:1528-1534
4. Kenefick RW, St Pierre A, Riel NA, Cheuvront SN, Castellani JW 2008 Effect of increased plasma osmolality on cold-induced thirst attenuation. European journal of applied physiology 104:1013-1019
5. Doubt TJ 1991 Physiology of exercise in the cold. Sports Med 11:367-381
6. Petrofsky JS, Burse HL, Lind AR 1981 The effect of deep muscle temperature on the cardiovascular responses of man to static effort. Eur J Appl Physiol Occup Physiol 47:7-16
7. Blomstrand E, Kaijser L, Martinsson A, Bergh U, Ekblom B 1986 Temperature-induced changes in metabolic and hormonal responses to intensive dynamic exercise. Acta physiologica Scandinavica 127:477-484
8. Doubt TJ, Hsieh SS 1991 Additive effects of caffeine and cold water during submaximal leg exercise. Medicine and science in sports and exercise 23:435-442
]]>Glucose (maltodextrin) and galactose are transported from the gut to the blood by a protein transporter. This transporter is the Na+/glucose co-transporter 1 or SGLT1 (Shirazi-Beechey, 1990) and like all transport proteins, can become saturated at high concentrations of glucose, becoming a bottleneck for energy absorption.
There is a limit to how much and how fast glucose can be absorbed, and therefore utilized by working muscles using only one type of carbohydrate transporter.
Fructose, a simple sugar, is transported using a totally different transporter called GLUT5 (Davidson, 1992). The benefit here is that now you can add a simple sugar to a drink containing maltodextrin (glucose), and not be limited by only one carbohydrate transporter. Using more than one carbohydrate transporter allows a greater rate of carbohydrate uptake compared to only one type of carbohydrate at a time. Studies have been done adding fructose to a maltodextrin drink, and found the addition of fructose increased total carbohydrate transport and, ultimately oxidation (Jentjiens, 2004, Wallis, 2005). Peak rates of carbohydrate oxidation using maltodextrin alone were approximately 1.1 g/min, which increased to 1.5 g/min with the addition of fructose (Wallis, 2005). More carbohydrate oxidation using fructose + maltodextrin (36% in this case) means better sparing of glycogen stores. It also allows an athlete to exercise at a higher percent of VO2max once those precious glycogen stores have been depleted and they are reliant on exogenous carbohydrate (Smith, 2010).
Varying the types of sugar (and thus carbohydrate transporters) improves the rate at which the carbohydrates are used by working muscles.
Simple sugars have also been shown to increase the content of SGLT1 receptors in the gut (Shirazi-Beechey, 1996). Therefore, by eating high carbohydrate diets and simple sugars, you can actually train your body to digest and process more carbohydrate energy (Ferraris and Diamond, 1989, Moran 2010).
More transporters mean less chances of a bad stomach on race day, and the ability to absorb and utilize more carbohydrates during exercise.
Fructose and simple sugars do not limit the amount of energy that can be digested and used for energy – the opposite is true. The addition of fructose to maltodextrin allows the athlete to tap into multiple carbohydrate transport proteins, increasing the rate of carbohydrate transport by the gut, promoting increased carbohydrate oxidation compared to maltodextrin alone. Therefore, despite claims to the contrary, simple sugars such as fructose play an important role in carbohydrate supplementation for endurance athletes.
]]>Hyponatremia is defined as low blood salt (sodium) concentration (<135mmol/L). Untreated, this can lead to seizure, coma, and death. The general consensus is that hyponatremia is caused by dilution – or ingesting water and/or sports drinks in excess, however it can also be caused from abnormal fluid retention by the kidneys. Exercise induced hyponatremia was first reported in the mid 1980’s (5, 7). However, the awareness of exercise hyponatremia increased dramatically in 2005 with a publication in the world’s top medical journal.
In 2005, Almond et al. published a paper in the New England Journal of Medicine on the prevalence of hyponatremia during the 2002 Boston marathon (1). This study showed that of the 488 people providing a usable sample, 13% had hyponatremia – which makes this condition more common than previously thought. This publication put the fear of exercise-induced hyponatremia in the forefront of the minds of race directors, as well as physicians providing medial coverage for endurance events. As a reaction, the governing body for marathon physicians (International Marathon Medical Directors Association) has made a recommendation that individuals “drink to thirst” to avoid hyponatremia during these events.
A global recommendation to drink to thirst may be appropriate for a 6 hour marathoner who exercises at low intensities, and therefore has lower rates of heat production and sweating, and more time on the course to drink. However, this recommendation could put faster athletes in harms way from dehydration and heat stress since they exercise at higher intensities that result in higher rates of heat production and sweating. At the very least, this recommendation to drink to thirst will hinder athletes achieving their potential, and could promote dehydration which has a dramatic effect on exercise performance (2, 4, 6). Exercise performance is decreased by dehydration resulting from as little as a 2% drop in body weight (8), so if athletes just rely on a sense of thirst to drive fluid intake they may become dehydrated.
There have been many studies documenting the challenges of preventing dehydration during exercise (2-4, 9). For most athletes, fluids cannot be consumed during exercise at a rate to match the rate at which fluids are lost. When athletes drink when they feel like it, instead of on a schedule, they become more dehydrated (3). Studies showing better performance with more hydration during exercise is the basis for recommendations for athletes to drink before they are thirsty, and drink to a schedule (one bottle of fluids per hour, etc..).
In fact, in individuals seeking medial attention after the Boston marathon from 2001-2008, under-hydration is almost 6x more common than over hydration (10). So should a recommendation not to over-drink be globally administered when not drinking enough is a problem faced by 85% of participants with fluid balance issues seeking medical attention after a marathon?
It is logical for race physicians to make recommendations to prevent deaths during athletic events – as that should be everyone’s goal. However, these recommendations may prevent individuals from performing to their full potential. We want to provide recommendations for athletes, in hopes of preventing both hyponatremia (overhydration), as well as dehydration, heat stress, and poor performance (underhydration).
Let’s explore the two biggest risk factors for hyponatremia during the Boston marathon in 2002 (1) that have also been supported by the American College of Sports Medicine (9):
Weight gain during exercise from over-hydration
This is the single biggest predictor of who may develop hyponatremia during exercise. People that gained weight did so because of consuming too much fluid. To prevent over-hydration, individuals should weigh themselves before and after exercise to make sure they are not gaining weight. Most people will lose weight – and the amount of weight loss will give valuable feedback that the athlete is not drinking enough during exercise. Some individuals will gain weight, and that weight gain is most likely from drinking too much. Based on feedback from the scale after exercise, individuals should adjust the volume of fluids consumed. Preventing weight gain during exercise should prevent almost all cases of exercise-induced hyponatremia
Longer race times
Individuals who take a longer amount of time than others to complete an endurance exercise event are at a higher risk of developing hyponatremia. Taking a longer time to complete a marathon or other endurance event means that the exercise intensity is lower than those who complete the event faster. This translates to less heat production, and possibly lower sweat rates – although this is quite variable. Slower speeds also make it easier to physically drink during running events, in addition to having more time to drink on the course.
Two other factors predisposing individuals for hyponatremia are low sweat rates during exercise, as well as being smaller and less lean.
Type of fluid consumed
Sports drinks contain sodium and electrolytes, but they are still much less dense in both compared to our blood (they are hypotonic). As a result, even sports drinks can promote hyponatremia by diluting blood sodium from over-drinking. So individuals that become hyponatremic are not just drinking water – they are drinking too much of all fluids.
Gender
In the Almond study, it did not matter if individuals were male or female – both genders are equally at risk. However, others suggest that women may be at greater risk than men (9).
So the takeaway from this study is that slower men and women athletes have more time to over-consume water or sports drinks on race day and are at risk for developing hyponatremia. While relatively less probable to occur compared to dehydration, prevention is key to avoid hyponatremia related illness.
How do you prevent hyponatremia?
Know thyself. Each athlete needs to test hydration strategies during training in order to properly execute race day hydration. Do you lose weight when working out? Gain weight? Do you sweat profusely or hardly at all? Each athlete must know how they respond to exercise, and how much they need to drink in order to prevent weight gain, and minimize weight loss during exercise. Every workout before an event is an opportunity to evaluate if an athlete is drinking too much or too little. Minimizing weight changes during exercise will also minimize the chances of dehydration, as well as hyponatremia from over hydration.
What else can be done to prevent hyponatremia?
Consuming salt tablets during exercise will increase sodium intake and help combat hyponatremia. Additionally, consuming GU or Roctane gels during exercise can also help prevent hyponatremia. GU contains approximately 50mg of sodium, while Roctane contains approximately 125mg of sodium, (about half as much sodium as 500ml of the average sports drink) – and because that sodium is not in a large volume, it can help prevent dilution of blood sodium from drink consumption during exercise.
What if you are one of the many athletes who lose weight from dehydration during exercise?
Join the club! Maximal sweat rates exceed maximal rates of fluid absorption by the gut, and most athletes do not consume enough fluids to maximize gut fluid absorption (8). Many, if not most, athletes cannot consume enough fluid during exercise to match rates of loss, which has been documented by many studies (2, 4). Therefore, pre-hydration before exercise starts can help make sure athletes start the event in a hydrated state, and can improve performance (6). Athletes who lose weight during exercise should try and minimize those losses by increasing the volume of ingested fluids during exercise to what is tolerable by their gastro-intestinal track – as is recommended by the American College of Sports Medicine (8). For every pound that is lost, approximately 500ml of additional fluid needs to be ingested (8).
For athletes who lose weight during exercise, thirst may not always be the best indicator of hydration status. Therefore, it is important to drink before you are thirsty to help minimize loss of body weight from dehydration during exercise.
Hyponatremia is a dangerous condition of low blood sodium concentration that can occur during exercise. Most cases of hyponatremia are due to over-consuming water and sports drinks during exercise, and are more common in athletes taking more time to complete endurance events. To the contrary, dehydration is also a problem during exercise, can result in heat stress and poor performance, and is more common in athletes taking less time to complete endurance events. As a result, one size fits all recommendations for hydration are prone to error and need to be tailored to each athlete. Luckily, athletes train before endurance events, and each training session can be used to provide feedback on hydration. Athletes should weigh themselves before and after training sessions to determine if they are consuming too little, or too much fluid during exercise, and hydration habits changed accordingly. Most athletes will lose weight during exercise, and should consume an extra 500ml of fluid for each pound of weight lost. Some athletes who are at risk for hyponatremia will gain weight during exercise, and should consume 500ml less fluid per pound of weight gained. Athletes need to pay particular attention to how environmental temperature, and intensity of exercise impact fluid requirements. Through trial and error in training, athletes will be better able to judge fluid requirements on race day to maximize performance and prevent under and over-hydration.
1. Almond CS, Shin AY, Fortescue EB, Mannix RC, Wypij D, Binstadt BA, Duncan CN, Olson DP, Salerno AE, Newburger JW, and Greenes DS. Hyponatremia among runners in the Boston Marathon. The New England journal of medicine 352: 1550-1556, 2005.
2. Casa DJ, Stearns RL, Lopez RM, Ganio MS, McDermott BP, Walker Yeargin S, Yamamoto LM, Mazerolle SM, Roti MW, Armstrong LE, and Maresh CM. Influence of hydration on physiological function and performance during trail running in the heat. J Athl Train 45: 147-156, 2010.
3. Daries HN, Noakes TD, and Dennis SC. Effect of fluid intake volume on 2-h running performances in a 25 degrees C environment. Medicine and science in sports and exercise 32: 1783-1789, 2000.
4. Ebert TR, Martin DT, Bullock N, Mujika I, Quod MJ, Farthing LA, Burke LM, and Withers RT. Influence of hydration status on thermoregulation and cycling hill climbing. Medicine and science in sports and exercise 39: 323-329, 2007.
5. Frizzell RT, Lang GH, Lowance DC, and Lathan SR. Hyponatremia and ultramarathon running. JAMA : the journal of the American Medical Association 255: 772-774, 1986.
6. Goulet ED, Rousseau SF, Lamboley CR, Plante GE, and Dionne IJ. Pre-exercise hyperhydration delays dehydration and improves endurance capacity during 2 h of cycling in a temperate climate. J Physiol Anthropol 27: 263-271, 2008.
7. Noakes TD, Goodwin N, Rayner BL, Branken T, and Taylor RK. Water intoxication: a possible complication during endurance exercise. Medicine and science in sports and exercise 17: 370-375, 1985.
8. Rodriguez NR, Di Marco NM, and Langley S. American College of Sports Medicine position stand. Nutrition and athletic performance. Medicine and science in sports and exercise 41: 709-731, 2009.
9. Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, and Stachenfeld NS. American College of Sports Medicine position stand. Exercise and fluid replacement. Medicine and science in sports and exercise 39: 377-390, 2007.
10. Siegel AJ, d’Hemecourt P, Adner MM, Shirey T, Brown JL, and Lewandrowski KB. Exertional dysnatremia in collapsed marathon runners: a critical role for point-of-care testing to guide appropriate therapy. Am J Clin Pathol 132: 336-340, 2009.
]]>Nutrition plays an important role for races of all distances. Although 10Ks are relatively short, and people typically don’t deplete their glycogen stores (the body’s carbohydrate reserves) in this short period of time, it is still important to make sure that you are fueled up for optimal performance. Here are some things to keep in mind when considering your nutrition plan for a 10K:
Here at GU, we embrace the principle “Eating is Training.” To us, this means feeding your body the right nutrients, at the right time, in sufficient amounts to maximize recovery and encourage positive physiological adaptations. You only spend a small part of your day training, while most of your day is spent resting, recovering, and preparing for the next workout. Think of this time as an opportunity to improve your performance even more! So, during the weeks of training leading up to your 10K (and all the time, for that matter), try your best to eat a nutrient-dense, whole food-based diet.
Focus on Variety: Be sure cover all your nutrition needs by mixing it up. Shop seasonally to incorporate different types of produce year-round. Have a few different sources of protein each week (chicken, fish, dairy, tofu, etc.). Do your best to try new things and avoid getting stuck in a dietary rut!
Ample plants: Fill half your plate with fruits and veggies, and try to have at least one serving with each meal and snack. Three different colors of produce on your plate at mealtime is another goal to strive for.
Plenty of Protein: Muscles rely on it, and your muscles are what move you! Try to get 20 g at mealtimes, and include some protein with every meal and snack, or about every 3-4 hours throughout the day, to support lean muscle mass.
Limit processed foods and added sugars: Look for labels with only a few, easily recognizable ingredients or, better yet, no label at all! (Think produce section, meat counter, farmers markets, etc.). Added sugars pack in unnecessary “empty” calories and can cause big swings in energy levels that leave you in a mid-afternoon slump.
The Good Kind of Fat: Fats are essential for vitamin absorption as well as healthy joints, eyes, skin, hair, and nails. They help keep you fuller, longer, and make food taste richer. Avocados, fatty fish, nuts and seeds, olives, coconut, nut butters, and oils from these foods are all great, healthy sources of fat in the diet! Enjoy a serving with each meal.
Your training plan is designed for you to peak on race day, and your nutrition can be used for the same function. One popular term in the running community is “carb loading.” Carbohydrates are your body’s first choice of fuel as they’re quickly converted into glucose, or blood sugar, which is used to give you energy. Increasing carbs to boost glycogen stores can be effective, but think of it more as a steady uptick rather than a drastic pre-race splurge. Instead of going for the all-you-can-eat pasta dinner the night before, trying upping your carbohydrate intake 2-3 days leading into your race to stock your muscle and liver glycogen stores. Get in high quality carbs such as sweet potato, quinoa, or brown rice, and make sure to have your veggies and protein of choice.
In addition, make sure familiarize yourself with what foods work with your stomach in the weeks before your race. Experiment throughout your training to discover what foods you can or can’t tolerate before you get in your miles.
During the morning of your 10K, it’s important to make sure your stomach feels as good as your legs. We recommend getting a high carb, easily digestible meal 3-4 hours before your race, so by the time the gun goes off, you’ll have topped off your glycogen stores and won’t feel full or weighed down. If the race is super early or you can’t stomach a full breakfast before a race, be sure to eat a light snack, like an Energy Stroopwafel or Energy Gel to boost blood sugar levels. Even a piece of fruit or toast is better than going in empty!
Because 10ks are shorter and typically run at a faster pace, it’s important to go into the race with your energy and hydration levels primed. We recommend taking an Energy Gel 5 minutes before the start, making sure to wash it down with a few big gulps of water.
Here are some of our pre-race breakfast favorites:
On race day, what matters most is that your mind is on performance — and not on your stomach — when the gun goes off. Be sure to eat familiar foods that you know work for you. Protein and fat slow down digestion and make you feel more full, so take that into consideration when prepping your pre-race breakfast. In the days leading up to your race, start to increase your carbohydrate intake (you can find out more specifics on how much to increase it here.) Finally, trust your training. 10Ks are the culmination of weeks of consistent preparation, so be confident in your fueling plan and enjoy the ride.