Athlete’s Guide to Optimizing Bone Health

March 8, 2023March 5, 2023 by amystephens

Athlete’s guide to optimizing bone health

Why bone health matters

Bone stress injuries (BSI) such as stress fractures and stress reactions are common among athletes with a lifetime prevalence of 40%. They can happen suddenly, just as an athlete might be peaking with training. Most injuries can take about two months to recover. Newer research has identified certain risk factors to help prevent bone stress injuries. Female athletes that miss a period and male athletes that have low testosterone levels are at an increased risk. It’s NOT normal for a female athlete to miss a period. While a missed period is a key indicator that females are at risk of declining bone health, male athletes can also suffer bone stress injuries due to inadequate fueling. Bone injuries are not fully preventable, however there are dietary and lifestyle modifications that can reduce the risk. This blog is intended to educate athletes, parents and coaches about how to optimize bone health. I will explain the relationship of running to bone health and best strategies to optimize bone strength.

How bones are formed

Bones are dynamic tissues. They are breaking down and building up daily.

After a workout, bones are broken down and if adequate nutrients are available, bones will rebuild and remain strong. Rebuilding is dependent on energy availability. This requires eating enough not only to support exercise, but to backfill nutrition requirements for daily living. If there is a lack of nutrition or the energy balance is off, in addition to failing to repair the stress to the bone tissue itself, the muscles will not have enough energy to fire and protect bones, leading to additional damage. This process worsens over time.

Specific cells responsible for breaking down bones (osteoblasts) and building up bones (osteoclast). It’s important for there to be a balance between the two so that bone can maintain its strength. Bones need to be built up at the same rate they are broken down. If muscles are unable to produce adequate force due to under-fueling, the balance is upended. Typically, underfueling prevents bone from being reformed thereby disrupting the breakdown and growth cycle of bones. Disruption to bone formation can occur in as few as five days of underfueling.

Lack of nutrition doesn’t support homeostasis with bones. It doesn’t mean that all exercises cause bone injury; it’s the opposite. Exercise is helpful to strengthen bones because the muscles pull on ligaments and tendons which break bone down. If the body is fueled properly and adequately rested, bones will rebuild stronger. For both male and female athletes, 90% of bone mass peaks by age 20 and will continue, to a lesser extent until 30 years old (Specker).

Underfueling can lead to bone injuries

In a situation of chronic underfueling or inadequate energy balance, the muscles weaken and overuse injuries can develop. In order for the body to work properly, there needs to be a balance with food and activity. Running, in particular, puts excessive strain on bones which has both short-and long-term consequences.

Short-term consequences of under-fueling include increased prevalence of bone injuries which can take six-to-eight weeks to heal. They can come on suddenly, even if you think you’re doing all the right things.

Chronic underfueling has long-term consequences because training suppresses hormones that protect bones (estrogen/testosterone). Over time, gradual bone loss will occur and bones begin to lose density. During adolescent years, achieving maximum bone mass is critical to protect an athlete later in their sports career.

Risk factors for low bone mineral density (BMD)

Low testosterone (male athlete)

Amenorrhea (female athlete)

Inadequate calcium intake

Low Vitamin D levels

Eating disorder (past or present)

Dietary restrictions – vegan, gluten free, lactose free

Inadequate calorie intake

History of stress fracture

Sports at highest risk for bone injuries (Tenforde)

Swimming

Diving

Crew

Cross country

Impact of the menstrual cycle on bone health

A normal menstrual cycle lasts approximately 25-35 days, during which estrogen levels increase and decrease, causing menstruation. An abnormal menstrual cycle, either shortened or lengthened between periods, provides a warning sign that requires further evaluation, as it may indicate a hormonal imbalance. Hormonal imbalances such as suppression of estrogen occur if energy balance is not adequate.

Because estrogen plays a significant role in bone formation, fueling adequately to maintain healthy estrogen levels is essential. Low food intake disrupts estrogen production, preventing bones from reaching maximum strength. Changes in bone have been seen in as little as 5 days of underfueling. During phases of amenorrhea (absence of menstruation), bone growth does not occur. Over time, stress from exercise outpaces bone mass maintenance. This imbalance can lead to bone injuries in the short term and bone density issues (osteopenia/osteoporosis) in the future. This is particularly damaging if the athlete wants to continue a post-collegiate athletic career.

If an athlete has irregular periods, speak with a local sports dietitian for further evaluation. If irregular cycles persist, other medical conditions may be the cause. Reach out to your doctor or healthcare center to rule out medical causes of amenorrhea.

Birth control and bone density

Birth control pills have minimal effect on improving bone density. They work by controlling hormones to produce a period. However, the underlying issue of chronic underfueling is not addressed and the hormones are not working naturally to increase bone density. The effect of underfueling prevents the body from making enough hormones.

How to improve bone health

Ensure adequate calories/energy balance.

Eat on a schedule. Be proactive. One week of underfueling can drop bone density. Studies have shown that one missed meal can increase bone injury by 40%. Eating on a schedule can help ensure you are eating enough food to support exercise. Plan out meals and snacks to eat before and after workouts. If you know it’s going to be a busy week with travel, bring snacks to fill in gaps between meals. For student athletes, this might require snacking during class or for adult runners to eat during a meeting. The goal is to eat food on a regular basis so the body will function at an optimal level. When exercise exceeds food consumed, the energy available to support bones and other important functions is diminished. The body will prioritize movement and sacrifice bone health.

Target the right amount of calcium and vitamin D

Obtain nutrients mainly from foods, and supplement only when necessary to fill in gaps. The RDA for adolescent athletes is 1,300 mg calcium and 600 IU vitamin D. Many foods with calcium also contain adequate amounts of vitamin D. An adolescent athlete can meet calcium requirements with 3 servings of dairy per day. Try eating oatmeal made with milk, yogurt for a snack and adding cheese to sandwiches or as a snack.

Non-dairy athletes can meet calcium requirements by including soymilk, fortified orange juice, dark green leafy vegetables, chickpeas, and fish such as sardines and salmon.

Vitamin D is found in most foods that also have calcium as well as sunlight. Most athletes spend a lot of time outdoors training so supplementation is not always necessary. Sports that are mostly held indoors are at a higher risk of vitamin D deficiency such as swimming, gymnastics, track and field, and dance.

RDA

9-18 yrs old require 1,300 mg calcium and 600 IU Vitamin D

<70 yrs, 1,000 mg of calcium and 600 IU vitamin D

>70 yrs, 1,200 mg of calcium and 800 IU vitamin D

Please note that excessive calcium intake can be harmful and lead to medical issues. Speak with your doctor or healthcare provider about supplementation.

One cup of skim milk reduced stress fracture risk by 62% (Nieves).
“If skim milk were a medicine, it would be a blockbuster.” -Adam Tenforde, MD

Sleep

In addition to high energy demands of athletes, lack of sleep has an even greater risk for bone injury. Impaired sleep has been shown to cause up to 5 percent bone loss within one week (BenSasson 1994).

Exercise loading to build bones

Work with a trained physical therapist to help create a fitness plan that includes a variety of movements. Younger athletes will benefit from a variety of exercises rather than specializing in a single sport. For example, runners will utilize different muscle systems in soccer or basketball. Using multi-directional sports recruits more muscles that strengthen bones from different locations.

If you are worried about your bone density, reach out to a pediatrician, primary care doctor or sports dietitian that works with athletes.

References

Ben-Sasson SA, et al. Extended duration of vertical position might impair bone metabolism. Euro J Clin Investigation. 1994 Jun. Vol 24-6: 421-425. https://doi.org/10.1111/j.1365-2362.1994.tb02186.x

Chan JL, Mantzoros CS. Role of leptin in energy-deprivation states: normal human physiology and clinical implications for hypothalamic amenorrhoea and anorexia nervosa. Lancet. 2005 Jul 2-8;366(9479):74-85. doi: 10.1016/S0140-6736(05)66830-4. PMID: 15993236.

Nieves J, et al. Nutritional Factors That Influence Change in Bone Density and Stress Fracture Risk Among Young Female Cross-Country Runners. PMR Journal. 2010. Aug Vol 2, Issue 8. 740-750. https://doi.org/10.1016/j.pmrj.2010.04.020

Nieves JW. Bone. Maximizing bone health–magnesium, BMD and fractures. Nat Rev Endocrinol. 2014 May;10(5):255-6. doi: 10.1038/nrendo.2014.39. Epub 2014 Apr 1. PMID: 24686202.

Schoenau E, Frost HM. The “muscle-bone unit” in children and adolescents. Calcif Tissue Int. 2002 May;70(5):405-7. doi: 10.1007/s00223-001-0048-8. Epub 2002 Apr 19. PMID: 11960207.

Specker BL, Wey HE, Smith EP. Rates of bone loss in young adult males. Int J Clin Rheumtol. 2010 Apr 1;5(2):215-228. doi: 10.2217/ijr.10.7. PMID: 20625439; PMCID: PMC2897064.

Swanson CM, Shea SA, Wolfe P, Cain SW, Munch M, Vujovic N, Czeisler CA, Buxton OM, Orwoll ES. Bone Turnover Markers After Sleep Restriction and Circadian Disruption: A Mechanism for Sleep-Related Bone Loss in Humans. J Clin Endocrinol Metab. 2017 Oct 1;102(10):3722-3730. doi: 10.1210/jc.2017-01147. PMID: 28973223; PMCID: PMC5630251.

Tenforde AS, Fredericson M, Sayres LC, Cutti P, Sainani KL. Identifying sex-specific risk factors for low bone mineral density in adolescent runners. Am J Sports Med. 2015 Jun;43(6):1494-504. doi: 10.1177/0363546515572142. Epub 2015 Mar 6. PMID: 25748470.

Tenforde AS, Carlson JL, Sainani KL, Chang AO, Kim JH, Golden NH, Fredericson M. Sport and Triad Risk Factors Influence Bone Mineral Density in Collegiate Athletes. Med Sci Sports Exerc. 2018 Dec;50(12):2536-2543. doi: 10.1249/MSS.0000000000001711. PMID: 29975299.

Tenforde AS, Barrack MT, Nattiv A, Fredericson M. Parallels with the Female Athlete Triad in Male Athletes. Sports Med. 2016 Feb;46(2):171-82. doi: 10.1007/s40279-015-0411-y. PMID: 26497148.

Best Nutrition Bars for Athletes

January 26, 2023January 26, 2023 by amystephens

Athlete’s Guide to Choosing a Nutrition Bar

I always recommend a food first approach but sometimes fresh food isn’t always available. Athletes have high energy demands, and in order to maintain a positive energy balance, athletes need to eat throughout the day. This might be challenging for athletes that have long, busy schedules or a second practice. There are many nutrition bar options available, but I’ve narrowed it down to a few that have enough protein and carbohydrates for athletes.

Nutrition bars are a great way to offset hunger, prevent injury and help with recovery.

What to look for in a nutrition bar

Calories are a guide to know how much you need to eat. Most bars listed below are between 200-400 calories, which is an appropriate amount of calories for a snack. Athletes’ calorie levels can vary depending on time spent exercising and intensity. Therefore, calorie requirements can be as much as 2500-5000 calories for very active individuals, which can be hard to obtain in meals. If you need further guidance on calories, it’s best to work with a sports dietitian to help you determine the best calorie intake for you.

Fat is an important nutrient that has key functions in the body such as helping to keep you fuller for longer, carry fat soluble vitamins and help with energy balance. Keep in mind, bars with high amounts of fat can take longer to digest, so it might be best to consume them well before you begin a workout or use them as a post workout recovery food. Athletes can target about 70-80 grams of fat per day, which is about 10 grams fat per snack and 25 grams fat per meal.

Protein is important to help grow muscle and prevent muscle breakdown. To maximize muscle growth and repair, studies show that protein spread throughout the day will have the biggest impact on muscle growth. Protein slows down digestion and helps keep blood sugars steady. Aim for 10-20 grams protein per bar.

Carbohydrates are essential for fueling working muscles before a workout and for recovery afterward. In between workouts, an athlete’s body is constantly restocking glycogen and recovering, even at rest. Bars are a great way to keep the supply of carbohydrates continuous. Look for nutrition bars that have 30-60 grams of carbs in the form of oats, fructose, glucose or maltose.

Fiber is essential to helps grow good gut bacteria, stabilize blood sugars and promotes regular bowel movements. Dietary guidelines suggest 25-30 grams fiber per day. Look for bars with about 3-5 grams fiber. Keep in mind, some bars contain very high levels of fiber which can be challenging to have the day before an endurance event. Fiber expands in the colon creating an urgency to use the bathroom multiple times. This can be a problem for endurance athletes in a competition without a bathroom nearby.

Sugar is okay for athletes. Diet culture has taught us that sugar is bad, but athletes have much higher energy demands and sugar can be part of a healthy diet in small quantities. Aim for bars with natural sugars such as honey or maple syrup on the label. Fructose and maltose have been shown to increase glycogen stores quickly, which helps performance and recovery.

Best pre-workout bars

Here are a few suggestions for pre-workout bars. I selected these options below because they contained higher carbohydrates, low-fat and low -fiber. These nutriets tend to cause GI issues in some people. Studies support a greater amount of carbohydrates and less protein/fat/fiber before a workout.

Nature’s Bakery Fig

Nutrition facts:

200 calories

5 g fat

38 g carb

3 g fiber

3 g protein

What I love: These bars are easy to find in local grocery stores, they’re inexpensive and contain high-quality ingredients.

✓ GF, vegan

$6.44/12 bars ($.54 each)

Order

Kind Oat Bar

Nutrition facts:

150 calories

5 g fat

23 g carb

2 g fiber

3 g protein

What I love: Kind bars are available in most grocery stores and they contain five super grains such as oats, millet, buckwheat, amaranth, and quinoa.

✓ GF

$35.92/40 bars ($.90 each)

Order

Larabar

Nutrition facts:

210 calories

12 g fat

23 g carb

4 g fiber

5 g protein

What I love: Larabar has only six ingredients (almonds, dats, semisweet chocolate chips, apples, cocoa powder and sea salt) and they taste great. Good option if you’re on a budget.

✓ GF

$16.14/86 bars ($.90 each)

Order

Skratch energy bar

Nutrition facts:

220 Calories

9 g fat

30 g carb

3 g fiber

5 g protein

What I love: great for pre-workout quick fuel. Interesting flavors such as cherry pistachio or peanut butter and strawberry.

✓ GF, Vegan, Kosher

$29.94/12 bars ($2.50 each)

Order

Bobo’s (Oat bar)

Maurten Solid

Nutrition facts:

340 calories

12 g fat

62 g carb

4 g fiber

6 g protein

What I love: Bobo’s are sold in local grocery stores and available in a bunch of interesting flavors such as chocolate almond and maple pecan. They can be broken in half for two snacks.

✓ GF, vegan

$29.88/12 bars ($2.49 each)

Order

Nutrition facts:

225 calories

3.6 g fat

41.5 g carb

2.4 g fiber

2.9 g protein

What I love: The fructose-glucose syrup is an ideal ratio for energy production plus the low fiber content make this a great choice for pre-workout fuel.

✓ GF

Cost $36.00/12 bars ($3.00 each)

Order

Best post-workout bars

These are my suggestions based on the nutrient composition. I generally look for a 4:1 ratio of carbohydrates to protein. This ratio has been shown to maximize glycogen stores, stimulate muscle protein synthesis and promote recovery.

Macrobar

Nutrition facts:

290 calories

11 g fat

39 g carb

2 g fiber

11 g protein

What I love: GoMacro is a great tasting vegan bar with protein from almond butter. Also has a snack size version.

✓ GF, Vegan

Cost $38.95/12 ($3.25 each)

Order

Clif

Nutrition facts:

235 calories

5 g fat

43 g carb

5 g fiber

11 g protein

What I love: Clif bars are available in many local grocery stores. I also like the 4:1 carbohydrate: protein ratio which is great for recovery after a workout.

✓ GF

$18.77/18 bars ($1.04 each)

Order

Rxbar

Nutrition facts:

210 calories

9 g fat

23 g carb

5 g fiber

12 g protein

What I love: RXBars have tons of flavors and they are easy to purchase, plus they are small enough to easily fit in your pocket.

✓ GF

$23.37/12 bars ($1.95 each)

Order

Over Easy

Nutrition facts:

230 calories

11 fat

24 g carb

6 g fiber

10 g protein

What I love: Over Easy bars are a great breakfast option as recovery food. They have a ratio of 2:1 carbs to protein which can help build glycogen and stimulate muscle protein synthesis (MSP).

✓ GF, dairy free

$29.69/12 bars ($2.47 each)

Order

Eating Disorders in Athletes: Impact on Performance

October 25, 2022October 25, 2022 by amystephens

Eating Disorders in Athletes: Impact on Performance

Eating disorders affect an athlete both mentally and physically and have significant impacts on performance. This blog will discuss the prevalence of eating disorders, identify warning signs in athletes, distinguish the differences and similarities to relative energy deficiency syndrome (REDS), and provide resources for those struggling to seek help. Eating Disorders are a serious issue for everyone, but especially for athletes. Nutrition requirements are high and the inability to fuel an athlete’s body will lead to worsening of disordered eating, injuries, and overall decline in performance.

The most common forms of eating disorders are anorexia, bulimia and binge eating disorder. Anorexia refers to restriction of food and refusal to meet nutritional needs, typically resulting in extreme weight loss. Bulimia is defined by consuming a large quantity of food in a short period of time, followed by a desire to “get rid” of the food through vomiting, exercise, or medications. Often, athletes can have a combination of both. Binge eating disorder is another type of eating disorder characterized by consuming a large quantity of calories in a short period of time. In one study, up to 84% of athletes were found to have subclinical disordered eating, and engaging in maladaptive eating and weight control behaviors, such as binge eating, excessive exercise, strict dieting, fasting, self-induced vomiting, and the use of weight loss supplements (Chatterton, Clifford). Evaluation by a physician or therapist can determine the severity and best form of treatment.

Eating disorders do not discriminate as they affect all races, genders, and socioeconomic classes. Some populations have higher rates of eating disorders. Eating disorders are most commonly screened and diagnosed between the ages 12-19, but can occur at any age. The earlier an athlete is diagnosed, the more likely they are to recover and reverse any damage to their bodies. The longer an eating disorder behavior is untreated, the more difficult the treatment and full recovery become.

Prevalence

13.5% of athletes struggle with an eating disorder (Ghoch).
Up to 45% of female athletes and 19% of male athletes struggle with an eating disorder (Bratland-Sanda)
In a study by Petrie, 19.2% of athletes surveyed had maladaptive eating behaviors such as restricting food intake, limiting food choices, excluding large groups of foods, and purging behavior.

Risk factors for developing eating disorders in athletes

Certain sports that are weight dependent and focus on leanness pose a bigger risk for eating disorders. Both male and female athletes are at risk.

In addition, athletes who have recently undergone stressful events such as an injury are at a greater risk for developing an eating disorder. Athletes who have been struggling with poor performance might want to restrict food and blame the body.

There are additional societal contributions that can lead to eating disorders. It’s important to be aware of these factors so proper education for athletes and coaching staff can help prevent disordered eating among athletes.

Societal contributions include:

A fixation on thinness and the need to have a certain appearance in order to be happy or successful
Social media’s tendency to reinforce negative body image by giving attention to overly thin athletes
Restrictive diet plans promoted by ill-trained professionals
Society’s fixation on toxic positivity and the need to seek perfectionism to achieve one’s goals

All of these practices promote unhealthy relationships with the body and eating patterns. Athletes are no exception. Weight dependent sports not only encourage unhealthy dietary practices, but reward them. The thinner athletes promote themselves as having reached their performance levels due to their thin body type. Misinformation from friends, coaches, and media can cause an athlete to try and achieve an inappropriate level of thinness that causes physical and mental harm to their body. Eating disorders are often overlooked if the athlete is performing well.

Difference between eating disorders and Relative Energy Deficiency Syndrome (RED-S)

Relative Energy Deficiency Syndrome (REDS) is a new classification of symptoms identified in 2014 by International Olympic Committee Mountjoy. REDS is characterized by low calorie intake in relation to energy exerted during exercise. REDS was formerly named “The Female Athlete Triad Syndrome because it affected three key systems in the female body:low calorie intake, menstrual irregularities, and lowered bone density. The term REDS is new but the condition has been in existence for a long time. Simply put, exercising too much and not eating enough causes an imbalance in which the body cannot function at optimal levels. What’s most interesting to me is that someone with REDS can be any body weight. The difference between REDS and an ED is that REDS is an unintentional mismatch of calories. Once an athlete with REDS is evaluated and educated about an appropriate amount of calories to sustain daily exercise and body functions, the deficit is corrected and the body can function properly. ED is further explored if the athlete is unable to willingly consume calories to support energy expenditure.

Sometimes it may not be obvious or easy to diagnose REDS or eating disorders. Someone can be a normal weight but is exercising too much and refueling inadequately. In this instance, athletes may feel that they are eating well, but in truth, are not eating enough calories to support exercise.

Signs of chronic underfueling that warrant further screening to determine if disordered eating is present

Females – change in menstrual cycle, can be longer or lighter periods, it is NOT normal for a female athlete to miss a period
Males – low testosterone and growth hormone. Both are natural performance enhancing hormones made by the body. Low levels can negatively affect sport performances, muscle growth, and energy production. Also important for serotonin uptake for the brain, it can lift mood. (Skolnick)
Hormonal changes can lead to stress fractures and ultimately osteoporosis
Frequent injuries to bones and soft tissues
Isolated, eats alone
Withdrawn behavior
Sudden changes with diet or food choices
Noticeable fluctuations in weight, both up and down
Irritability
Lethargy, difficulty finishing a workout
Digestive issues such as bloating (often mistaken for IBS), gas, diarrhea (this is often worsened by further restricting suspected nutrients)
Decrease in sports performance
Difficulty sleeping
Not seeing improvements in performance despite increasing workouts
Depressed immune system
Decreased cognitive functioning (lower blood sugar supplied to brain)

Treatment

Treatment often begins with an evaluation by a physician, eating disorder dietitian, and therapist. Once the patient is evaluated, they are recommended to the best form of treatment depending on their situation. The dietitian will create a plan that provides adequate calories to support daily expenditure. It can be challenging to find the right physician to help especially since there are differing opinions among professionals. In my experience, missing a period leads to complications related to menstrual cycle and bone growth. It is important to let your doctor know if you’ve lost your period for more than three months as this can be related to underfueling or the result of underlying medical conditions. Your doctor can help guide you to the best treatment approach.

Resources for help

There are many resources to help. If you or someone you are close to might have an eating disorder, here are some important resources that can help:

- Visit your doctor and explain why you are concerned. Be sure to ask if your doctor works with eating disorders.
- For college athletes, visit your health center and explain why you are concerned. The health professionals can conduct proper screenings and assessments.
- Seek out a sports dietitian (ask if they have experience with eating disorders)
- See a school psychologist
- If you think you have an eating disorder, speak to a trusted family member or friend and share your concerns. Eating disorders are isolating so speaking out is a step in the right direction.
- Seek out supportive teammates and coaches and share your eating concerns. They can help you locate the best resources for an evaluation and assessment.
- National Eating Disorders Hotline (NEDA) 1-800-931-2237

References

Bratland-Sanda S, Sundgot-Borgen J. (2013). Eating disorders in athletes: overview of prevalence, risk factors and recommendations for prevention and treatment. Eur J Sport Sci, 13(5):499-508.

Chatterton, J. M., & Petrie, T. A. (2013). Prevalence of disordered eating and pathogenic weight control behaviors among male collegiate athletes. Eating Disorders, 21(4), 328-341.

Clifford, T., & Blyth, C. (2018). A pilot study comparing the prevalence of orthorexia nervosa in regular students and those in university sports teams. Eating and Weight Disorders – Studies on Anorexia, Bulimia and Obesity, 24(3), 473-480.

Conviser, J. H., Schlitzer Tierney, A., Nickols, R. (2018). Essential for best practice: treatment approaches for athletes with eating disorders. J of Clin Sports Psych, 12.

Ghoch, M. E., et al. (2013). Eating disorders, physical fitness, and sport performance: a systematic review. Nutrients, 5:12.

Mehler, P.S., Sabel, A.L., Watson, T. and Andersen, A.E. (2018). High risk of osteoporosis in male patients with eating disorders. Int. J. Eat. Disord, 41: 666-672.

Mountjoy M, Sundgot-Borgen JK, Burke LM, et al. (2018). OC consensus statement on relative energy deficiency in sport (RED-S): 2018 update. Brit J of Sports Med, 52:687-697.

Petrie, Trent, Greenleaf, Christy, Reel, Justine, Carter, Jennifer. (2018). Prevalence of Eating Disorders and Disordered Eating Behaviors Among Male Collegiate Athletes. Psych of Men & Masculinity, 9: 267-277.

Scott CL, Plateau CR, Haycraft E. (2020). Teammate influences, psychological well-being, and athletes’ eating and exercise psychopathology: A moderated mediation analysis. Int J Eat Disord, 53(4):564-573.

Shufelt CL, Torbati T, Dutra E. (2017). Hypothalamic Amenorrhea and the Long-Term Health Consequences. Semin Reprod Med, 35(3):256-262.

Skolnick A, Schulman RC, Galindo RJ, Mechanick JI. (2016). The endocrinopathies of male anorexia nervosa: case series. AACE Clin Case Rep, 2(4):e351-e357.

How to prevent GI issues in runners

October 4, 2022September 6, 2022 by amystephens

How to prevent gi issues in runners

We all know far too well that gastrointestinal issues can derail a training run or race physically and mentally. Cramping, bloating, and diarrhea can quickly worsen dehydration and become very painful or even debilitating. In this post, I outline some easy strategies to help you feel better and improve performance when facing GI issues. By following these nutrition strategies, one can improve symptoms and performance as a whole.

GI issues can happen before, during, or after a run and can rapidly cause dehydration and electrolyte imbalance. If GI issues are not addressed, they can lead to underfueling, cramping, and poor performance. Underfueling will eventually lead to hitting the wall, or even dropping out of a race altogether.

Why do GI issues happen with some athletes?

There are a few reasons for GI issues in runners.

As you run, the stomach and gut are literally being shaken, and this makes it difficult for your body to digest foods.
Running also requires the body to divert blood flow away from the gut to supply oxygen rich blood to the working muscles. This process makes it very difficult for the body to digest food and run at the same time.
Feeling nervous can also cause GI issues. Nervousness is something I’ve experienced myself during track workouts! Typically, if I dive a bit further into how an athlete feels before a race or track workout, feelings of nervousness usually surface. Breathing and mental exercises can help soothe an athlete’s nerves. Similar to running, feeling nervous takes blood supply away from the gut and diverts it to the nervous system to cope with stress (elevated heart rate, sweat, increased blood supply to brain, etc.).

Nutrition strategies to prevent GI issues:

It’s important for athletes to ensure they’re hydrated before heading out for a run. When exercising, the blood is shunted to working muscles and away from the gut causing a lower blood volume. Ultimately, any food or sports beverage you consume during a workout may cause GI distress.

Time meals so you finish eating at least one hour before running. Work with a sports dietitian to time your food so it’s digested by the time you start exercising.

Hydrate by drinking 10-20 oz of water one hour before a run and 2-4 oz every 15 min for runs lasting one hour or longer. You might need to do a sweat test to see how much water your body loses. Take note that you lose more water when exercising in hot, humid, dry, and high altitude.

Foods – Include bland foods such as, rice, bananas, oatmeal, dry toast, or potatoes before your run. Another dietary strategy is called Low Fodmap which has been shown to help with GI symptoms. I’ll write more about this and how to follow in a separate post.

Quick tips:

Eat at least one hour before running
10-20 oz of water before, then 2-4 oz every 15 min (depending on heat, humidity, altitude)
Limit caffeine or switch to tea
Limit spicy foods, high-fat foods, high-fiber foods (beans or lentils) or dairy.

Try these gu’s, gels, and chews during your run because they are made with fewer processed ingredients. Instead of maltodextrin, they use monosaccharides like glucose and fructose which are easier for the body to digest. They are best tolerated with a gulp of water.

Try these Gels, Gu’s or chews

Gels/Gu’s

Honey stinger – website

Untapped energy gels – website

Huma energy gels – website

Energy chews are great because you can ingest them at a slower rate. This allows your gut to work more slowly and not cause GI issues. For best results, you may take a few at a time.

Liquid sports drinks such as Skratch or Maurten can be helpful because they are hydrating and can be taken in a small amount at a time. When using, be careful not to overwhelm the gut by ingesting too much too fast.

You can also ask your doctor about the over the counter medication called imodium.

References

Gibson PR, et al. Other dietary confounders: FODMAPS. Dig Dis. 2015;33(2):269–276.

Lis DM. Exit Gluten-Free and Enter Low FODMAPs: A Novel Dietary Strategy to Reduce Gastrointestinal Symptoms in Athletes. Sports Med. 2019 Feb;49(Suppl 1):87-97.

O’Keeffe M, Lomer MC. Who should deliver the low FODMAP diet and what educational methods are optimal: a review. J Gastroenterol Hepatol. 2017;32(Suppl 1):23–26.

Staudacher HM, et al. Comparison of symptom response following advice for a diet low in fermentable carbohydrates (FODMAPs) versus standard dietary advice in patients with irritable bowel syndrome. J Hum Nutr Diet. 2011 Oct;24(5):487-95.

Athlete’s Guide to Reducing Inflammation

October 5, 2022September 6, 2022 by amystephens

Athlete’s Guide to Reducing Inflammation

What is inflammation?

In the world of sports and athletics, all athletes experience inflammation. Inflammation is a natural and healthy process by which the body protects itself from harm. Intense exercise causes metabolic waste as toxins are released, causing the body to respond. Inflammation is the process whereby the body heals itself from toxins.

Athletes perform at extraordinarily high levels, whether it’s running a marathon or playing a three hour tennis match in 100 degree weather, which can greatly affect the body. The need to take care of one’s body after these extreme efforts is essential to the process of reducing inflammation. The main jobs of an athlete are to workout, get stronger, and recover.

C-reactive protein (CRP) is an inflammatory protein that can be measured to determine the level of inflammation in the body. Higher levels of CRP are found in your blood after a workout and can persist for a few days. Your body can naturally lower CRP levels but this process can take a few days. During this time, muscle growth and repair are inhibited.

There are many different tools to reduce inflammation, but healthy eating is the single most important factor in reducing inflammation. Foods improve recovery and one’s own ability to perform. Many athletes will undergo procedures to lower inflammation but nothing is more potent than eating anti-inflammatory foods because healing nutrients are delivered directly into the body. These anti-inflammatory properties begin when certain foods are passed through the gut. There, certain nutrients such as omega-3’s, antioxidants (Vitamin C, E and A), and probiotics are absorbed into cells. Other foods like saturated fats and processed sugars have been shown to increase inflammation throughout the body.

Here is a list of foods that will reduce inflammation:

Tart cherry juice is a convenient source of Vitamin C and potassium which are used to restore electrolytes and promote recovery.

Vegetables such as peppers, broccoli, kale, beets (beet juice), and spinach are high in Vitamin C and antioxidants.

Berries and citrus fruits are also rich in antioxidants, Vitamin C, and anthocyanins. Best sources include: strawberries, blueberries, blackberries, raspberries, oranges, and grapes.

Green tea contains catechins which suppress the inflammatory protein response. (Ohishi)

Turmeric contains an ingredient called circumin which has been shown to reduce inflammation. Turmeric is most commonly used as a seasoning. To make tea, use 1 tsp ground turmeric and mix with warm milk (also a great source of iron).

Nuts and seeds such as chia seeds, almonds, walnuts contain monounsaturated fats and alpha linoleic acid (ALA) which has been shown to reduce levels of CRP. They are also rich in fiber which slows the release of glucose into the cells, also referred to as low glycemic foods. Peanuts are a great, less expensive option.

Avocado and Olive oil are great sources of monounsaturated fatty acids. These fats help raise good cholesterol and maintain the body’s cells. These foods are also rich in Vitamin E which is an antioxidant that helps fight inflammation.

Fatty fish such as salmon, sardines, anchovies, and mackerel are rich in omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Omega 3’s have properties that interrupt the inflammatory process, similar to aspirin (Calder).

Probiotic yogurt has been shown to lower levels of CRP and inflammation in the gut. The bacteria from yogurt protects the gut from invading viruses and bacteria and offsets proteins released during prolonged exercise (Forseth and Bienstock). Kefir and plain low-fat Greek yogurt are great because they have many strands of live cultures. (Salehzaden).

In addition to food, sleep and stress reduction will reduce inflammation by allowing hormone levels to reset so it can repair damaged tissue.

Sleeping 8-10 hours per night will help restore stress hormone levels and reduce inflammation (Mullington).
Reducing stress by practicing breathing exercises, yoga, taking a walk, or sitting quietly.

These foods cause inflammation

When you consume these foods in your diet, studies have shown elevated CRP levels.

Alcohol

Refined carbohydrates made with white flour do not contain many nutrients or fiber. They have a higher glycemic response which has shown to increase inflammation. These foods include: sweets, cookies, ice cream, pastries, cakes, processed foods.
Saturated fats found in shortening, lard, red meat, smoked meats, hot dogs, hamburger, sausage, fast food and fried foods. These foods have been shown to raise bad cholesterol levels and contribute to inflammation.

Sample meal plan

Breakfast

Bowl of plain low-fat yogurt with almonds and berries and top with chia seeds

Post-workout snack

Toast with almond butter, berries, glass of tart cherry juice

Lunch

Spinach salad with avocado, chickpeas, and pumpkin seeds, olive oil and vinegar dressing

Quinoa or brown rice bowl with broccoli and peppers and grilled salmon

Blueberry smoothie made with plain yogurt

Snack

Grapes and almonds or walnuts

Chia pudding made with milk or almond milk

Green tea

Dinner

Chicken fajitas, sliced avocado, tomates, peppers and onions, tomato salsa

Easy chia pudding recipe

In small jar or covered container, mix together:

2 Tbsp chia seeds

½ cup milk

1 tsp honey

Shake well and refrigerate for at least 2 hours. Top with strawberries and cinnamon.

References

Calder PC. (2010). Omega-3 fatty acids and inflammatory processes. Nutrients, 2(3):355-374.

Forsythe P & Bienenstock J (2010). Immunomodulation by commensal and probiotic bacteria. Immu invest, 39(4-5): 429-48.

Kuczmarski MF, Mason MA, Allegro D, Zonderman AB, Evans MK. (2013). Diet quality is inversely associated with C-reactive protein levels in urban, low-income African-American and white adults. J Acad Nutr Diet, 113(12):1620-31.

Lankinen M, Uusitupa M, Schwab U. (2019). Nordic Diet and Inflammation-A Review of Observational and Intervention Studies. Nutrients,18;11(6):1369.

Mullington JM, Simpson NS, Meier-Ewert HK, Haack M. (2010). Sleep loss and inflammation. Best Pract Res Clin Endocrinol Metab, 24(5):775-84.

Ohishi T, Goto S, Monira P, Isemura M, Nakamura Y. (2016). Anti-inflammatory Action of Green Tea. Anti Inflam Anti Allergy Agents Med Chem, 15(2):74-90.

Salehzadeh, Karim. (2015). The Effects of Probiotic Yogurt Drink on Lipid Profile, CRP, and Record Changes in Aerobic Athletes. Int’l J Life Sciences, 9;(4)32-37.

How to change body composition in a healthy way

January 28, 2022September 12, 2021 by amystephens

change body composition in a healthy way

Why important

It has been proven that athletes with more muscle mass and less fat are able to run faster due to the power-to-weight ratio. Oftentimes, athletes will try to lose weight in an unhealthy way which can negatively affect performance and cause injury. This post reviews safe and effective strategies to lower body fat without compromising performance and mental health.

Factors influencing body composition

Genetic predisposition, age, sex, activity level, and dieting history are a few factors that affect body composition. As we age, our bodies have a greater percentage of fat tissue although studies have recently shown that can be mitigated with healthy eating and exercise. Gender is also a factor, as male athletes tend to have lower body fat composition while female-identifying athletes tend to have higher body fat.

Off season

In the off season, many athletes find themselves increasing weight. Rather than crash dieting to get back into shape, I created a guide to help decrease body fat without losing muscle or compromising performance and may cause injuries to ensue.

Performance

Running performance is based on a power to weight ratio. Increasing the amount of muscle and decreasing body fat enable an athlete to move faster through strides with less effort.

Oftentimes, athletes will cut calories and “diet” or utilize intermittent fasting in an effort to lower body fat and improve performance. However, these types of diets lead to depletion of glycogen and muscle mass. They are overly restrictive and the athlete often ends up regaining the weight, mostly as fat tissue which decreases performance.

The human body needs a combination of carbohydrates, fats and protein to perform at its best. I’ve compiled a list of tips below to help athletes lose fat in a healthy way without feeling deprived, compromise performance or lead to weight regain.

Carbohydrates

During a run, our bodies are using glycogen, a stored form of glucose, as the primary source of fuel. Easy and tempo runs (VO2max 50-80%) utilize a combination of fat and glucose for fuel. Harder track workouts (VO2max >80%) will use mostly glucose. Since our bodies are mostly using glucose for energy, replenishment after a run with carbohydrate-rich food is essential to improve training and overall fitness. Studies have shown that carbohydrates are the fastest source of energy to power a workout or run. Carbs convert into glucose at a faster rate than protein or fats and enable the athlete to run and continue running at a faster speed. Target about 5-8 grams of carbohydrates per kilogram of body weight per day (Burke).

Protein

Protein-rich foods are essential to help replenish amino acids used by muscles and repair muscle damage that occurs during eccentric exercises such as down hill running. If the diet is lacking in protein, muscle repair and growth will be negatively affected. Target 1.5-2.3 grams of protein per kilogram of body weight per day (Mettler).

Fat

Fat provides calories to support hormone production, which helps regulate many important functions in the body such as; menstruation, bone formation, or iron regulation. It’s important to get in enough healthy fat calories to keep you full and provide fat soluble vitamins. Aim for 20% of calories from fat per day.

To convert pounds to kilograms, divide by 2.2.

All of these nutrients are critical to achieving optimal performance so careful attention needs to be made especially during weight loss efforts. Several studies have shown that crash diets don’t work and can lead to muscle loss, slow metabolism, poor mood, and decreased performance. To decrease body fat in a healthy way, follow these tips:

Tips

Focus on timing of meals. Eat more food immediately before or after a run/workout and then prioritize eating a sensible meal when hungry with lots of fiber (brown rice, veggies, grilled chicken, turkey burger and salad).
Increase protein to stay full. Aim for 20-30 grams of protein per meal. Grilled chicken, sliced turkey, hard-boiled egg or edamame.
Cut back on added sugars from sweets or processed foods. Too much sugar can cause a sugar crash and leave you feeling lethargic and increase hunger.
Avoid getting too hungry, as this can lead to overeating.
Keep the refrigerator stocked with fruits, veggies, lean proteins like chicken, sliced turkey, low-fat cottage cheese, hummus, low-fat plain yogurt.
Snack on fruits, vegetables and small portions of nuts. Snack foods tend to be less nutritious and the calories can often add up to another meal. Add more food at meals to cut back on snacking. Use snacking as an opportunity to eat fruits + veggies. Veggies in dip such as hummus, peanut butter or tzatziki. Rice cake with peanut butter or yogurt with fruit.
Avoid weighing yourself daily. Your weight fluctuates daily from fluid shifts and seeing the scale increase and decrease can be discouraging.
Aim for at least 8 hours of sleep each night because sleep allows your stress and hunger hormones to reset. Hormones like ghrelin, insulin and cortisol increase during stress which affect metabolism. These hormones are responsible for increasing your appetite and storing fat and adequate rest will maintain an optimal balance.
Allow 10% of calories to be “fun foods” or less nutritious foods (approx 200-300 calories). If you include these foods in your diet, you are less likely to crave them.
You don’t need to clean your plate every time you eat. Restaurant portions are typically too large. Stop eating when you are full and save leftovers for later in the day or another meal.

Learn more about intuitive eating. This is a concept that focuses on hunger and satiety cues. Reconnect with how your body feels when you are hungry. Learning to slow down when eating by chewing slowly and taking breaks will help you recognize when you are full. These simple strategies will prevent overeating.

Sample meal plan

Breakfast

Pre workout

Oatmeal w/ banana + nuts or nut butter

Post workout

Chocolate milk, granola bar or green smoothie

Lunch

Rice bowl with grilled chicken and vegetables

Bowl of strawberries

PB&J with green smoothie – banana, ice, milk, peanut butter, and spinach

Snack

Plain low-fat yogurt with fruit

Dinner

Grilled chicken, salmon or turkey burger, baked potato, salad or steamed vegetables with olive oil and lemon

Dessert – blueberries or dark chocolate

Snack (optional)

Graham crackers and low-fat milk

References

Burke L. and Deakin V. (2015). Clinical Sports Nutrition (5th edition). North Ryde, N.S.W McGraw-Hill Education.

Close GL, Sale C, Baar K, Bermon S. Nutrition for the Prevention and Treatment of Injuries in Track and Field Athletes. Int J Sport Nutr Exerc Metab. 2019 Mar 1;29(2):189-197.

Jeukendrup AE. Periodized Nutrition for Athletes. Sports Med. 2017 Mar;47(Suppl 1):51-63.

Mettler S, Mitchell N, Tipton KD. Increased protein intake reduces lean body mass loss during weight loss in athletes. Med Sci Sports Exerc. 2010 Feb;42(2):326-37.

Stellingwerff T, Maughan RJ, Burke LM. Nutrition for power sports: middle-distance running, track cycling, rowing, canoeing/kayaking, and swimming. J Sports Sci. 2011;29 Suppl 1:S79-89.

Thomas D, et al. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. J Acad Nutr Diet. 2016 Mar;116(3):501-528.

Iron for endurance athletes

October 15, 2022September 10, 2021 by amystephens

Iron levels for athletes

Why iron deficiency is important

Iron is an important nutrient to endurance athletes because it carries oxygen and produces energy. Low levels of iron mean that fewer red blood cells are available to carry oxygen. Oxygen is essential to power muscles and the removal of metabolic waste so the body can function at peak performance. Many studies have reported the prevalence of iron deficiency in endurance athletes to be as high as 50% in females and 30% in males (Koehler 2012, Tan 2012). Although more common in female athletes, male athletes are also at risk for low iron. Often, athletes will report low energy levels or difficulty completing a workout, and later will find it’s iron deficiency. This post will review how iron impacts performance, symptoms of low iron, and how to prevent iron from impacting performance.

Stages of deficiency

Dr. Peeling defined stages of deficiency and depletion (2007). What’s interesting about these stages is that iron stores can be depleted while hemoglobin levels remain within normal range. It’s not until stages 2 or 3 of deficiency that an athlete begins to see a performance impact. Before a substantial training block begins, assessing individuals’ risk factors and low iron risk factors is helpful. If an athlete has a drop in iron during a racing season, treatment can take a few weeks, which can have a detrimental impact on the racing schedule. A basic iron assessment contains the following labs: ferritin, hemoglobin, and transferrin saturation. Your physician can order these tests and a sports dietitian can help interpret them and review best treatment options.

> Stage 1—Iron deficiency (ID): iron stores in the bone marrow, liver and spleen are depleted (ferritin < 35 μg/L, Hb > 115 g/L, transferrin saturation > 16%). Treat with food first approach by including many iron-rich foods along with Vitamin C.

> Stage 2—Iron-deficient non-anemia (IDNA): erythro- poiesis diminishes as the iron supply to the erythroid marrow is reduced (ferritin < 20 μg/L, Hb > 115 g/L, transferrin saturation < 16%). Initiate iron supplements 65mg elemental iron. Can take 4-12 weeks to show results.

> Stage 3—Iron-deficient anemia (IDA): Hb production falls, resulting in anemia (ferritin < 12 μg/L, Hb < 115 g/L, transferrin saturation < 16%). When levels are this low, consult with your physician about the cause and best treatment options.

NOTE: 325 mg ferrous sulfate is equivalent to 65 mg elemental iron.

Risk factors for low iron

There are a variety of factors that contribute to low iron levels. Any one of these risk factors can cause iron levels to drop, and multiple risk factors will carry an even greater risk for low iron. Endurance athletes are at the greatest risk due to the hemolysis from the footstrike and blood loss in the gut while running and sweat. During a training block, iron can drop 25-40% (McKay).

Menstruation for females
Underfueling/Low calorie intake (RED-S)
Endurance athletes
Altitude training
Vegan or vegetarian diets
Have a history of low iron stores

Symptoms

Initially, symptoms are not overt, however, you may feel tired overtime or less of a desire to complete a workout. Most common symptoms include: feeling lethargic, dizzy, negative mood, or poor performance (Sim).

Hepcidin

Hepcidin is a hormone released during exercise that inhibits iron absorption for 3-6 hours after a workout (Sim). This hormone regulates the amount of iron absorbed by the gut. Hepcidin levels are known to elevate 3-6 hours after a workout, thus reducing the amount of iron absorbed from food and supplements.

Iron- rich foods

There are two types of iron-rich foods – heme and non heme sources. Heme sources are more bioavailable compared to plant-based iron sources. Up to 35% of heme versus 20% iron from plants are absorbed (Beard). An athlete can add a Vitamin C food to further enhance absorption. If iron stores are very low or you are at a higher risk for iron deficiency, you may require iron supplements in addition to dietary intervention. Currently, the RDI for iron men is 8mg and 18 mg for women.

Heme iron

Beef
chicken
fish
turkey

Non-heme

Lentils, beans
Chickpeas, hummus (especially if made with tahini)
Spinach
Apricots, prunes
Baked potato with skin
Enriched breakfast cereals (Cheerios)
Enriched pasta

Click here for a full list of iron-rich foods from the USDA database.

Sample meal ideas

Grilled chicken over rice with roasted red peppers.

Turkey sandwich on whole wheat bread with an orange.

Spinach salad with chickpeas, dried apricots, and lemon vinaigrette dressing.

Key points

Iron is an important nutrient involved with energy production and promoting oxygen uptake. Iron deficiency can negatively impact performance in athletes by reducing oxygen transferred to the cells and making the body work harder to produce energy.

Females, vegetarians, calorie-restricted diets (RED-S), endurance athletes and training at altitude increase the risk for low iron.

Symptoms of iron deficiency include fatigue, negative mood and poor performance.

Hepcidin is a hormone that reduces iron absorption for 3-6 hours following a workout. The best time to take an iron supplement or eat an iron rich meal is outside this window.

Best food sources of iron include meat, fish, poultry, dark green leafy vegetables. Combine iron rich foods with Vitamin C to enhance absorption.

Certain foods will compete with iron absorption, such as calcium and phytates.

Speak with your physician or sports dietitian to help assess and treat iron deficiency.

References

Beard J, Tobin B. 2000. Iron status and exercise. Am J Clin Nutr. 72 (2):594S-597S.

Coates A, Mountjoy M, Burr J. Incidence of iron deficiency and iron deficient anemia in elite runners and triathletes. Clin J Sport Med. 2016.

Koehler K, Braun H, Achtzehn S, Hildebrand U, Predel H-G, Mester J, Schänzer W (2012) Iron status in elite young athletes: gender- dependent influences of diet and exercise. Eur J Appl Physiol 112(2):513–523

McKay, AKA, Peeling P, et al. (2019a) Chronic adherence to a ketogenic diet modifies iron metabolism in elite athletes. Med Science Sports Exercise. 51(3):548-555.

McKay et al. Iron metabolism: interactions with energy and carbohydrate availability. Nutrients. 2020 Nov 30.12(12); 3692

Ostojic SM & Ahmetovic Z. Weekly training volume and hematological status in female top-level athletes. Ahmetovic Journal of Sports Medicine and Physical Fitness; Sep 2008; 48, 3; ProQuest Nursing & Allied Health Source pg. 398

Peeling P, Blee T, Goodman C, Dawson B, Claydon G, Beilby J, Prins A (2007) Effect of iron injections on aerobic-exercise perfor- mance of iron-depleted female athletes. Int J Sport Nutr Exerc Metab 17(3):221–231

Sim et al. Iron considerations for the athlete: a narrative review. Eur J Appl Physiol. 2019 July; 119(7):1463-78

Tan D, Dawson B, Peeling P (2012) Hemolytic effects of a football-specific training session in elite female players. Int J Sports Physiol Perform 7(3):271–276

USDA database for iron rich foods

Hydrating in heat and humidity

May 14, 2022August 19, 2021 by amystephens

Hydrating in heat and humidity

Water is the forgotten nutrient

Exercise produces heat and leaves the body as sweat to stay cool. Studies have repeatedly shown that losing more than 2% body weight impacts performance (James). More sweat is produced when the temperatures are higher or when humidity is high. Dehydration results in an increase in one’s core temperature, reduced cardiovascular function and imparied exercise performance.

Essentially, dehydration increases an athlete’s perceived effort and reduces the ability to continue exercising at a high level (Nybo). If you’re overheating, the body will prioritize cooling itself versus rapid energy production (James).

Role of sweat

During exercise, the body produces heat and energy. Sweat is the body’s built-in cooling system that enables the body to make more energy. In warmer temperatures, exercise raises core temperatures at a faster rate which require more water expelled through the skin to keep the body cool. As temperatures increase, our bodies respond by sweating more. However, humidity compounds this problem by preventing evaporation. In situations where humidity levels are high, as we experience on the east coast all summer long, there is more moisture in the air and the sweat does not evaporate. As a result, the body’s core temperature increases, making exercise seem harder.

Dehydration affects performance

Many studies have shown that a 2% loss in body weight will impair performance (Lewis). The body has to work harder to keep the heart pumping to produce energy and muscles firing. Not only does it feel harder when you are dehydrated, but your body is also producing energy at a slower rate.

As core temperatures increase, energy metabolism shifts from aerobic production to anaerobic and this causes a buildup of anaerobic by-products that stimulate fatigue. This process occurs at a faster rate in hot and humid conditions. Fuel source shifts from fatty acids to glucose and amino acids and creates more hydrogen and lactic acid (Burke 2015). The heart receives less blood and therefore, less oxygen is delivered to working muscles. This makes exercising even more difficult in warmer conditions. Muscles have a harder time contracting when they’re overheated and premature fatigue can set in (Nybo).

Cramping

If you lose too much water, the risk of cramping is increased. Humidity increases risk of dehydration which causes an imbalance of electrolytes, especially potassium, magnesium and sodium. These electrolytes are lost at high levels through the skin and have a significant impact on cramping (Jung).

Dietary recommendations in the heat

Fluid requirements are individualized. Establish your sweat rate by using a sweat test to better estimate the amount of sweat you lose in one hour of exercise. Once you know how much fluid your body loses, you can more precisely match your fluid requirements. Estimate fluid losses by using a sweat rate calculator to input your weight and fluids. Calories do not need to be increased when exercising in heat (Burke).

Start drinking fluids when you wake up. Have a glass of water before you drink coffee!
Before exercising, urine should be a pale yellow color.
Exercise in the beginning or end of the day when it’s cooler
Don’t chug water without electrolytes, this can lead to hyponatremia.
You will rehydrate faster when fluids contain electrolytes and carbohydrates. This helps stimulate thirst and retain fluids consumed (Baker & Jeukendrup 2014).

Hyponatremia is caused by drinking too much water and not enough electrolytes. Make sure to have salt or nuun tablets handy. Water follows electrolytes and when you sweat, you lose both!

The color of your urine is the best indicator of hydration. Aim for pale yellow, shade 1 or 2 on the chart is ideal. Clear urine can indicate fluid overload and hyponatremia. If your urine is dark yellow before a run, delay the start until you can drink more fluids.

References

Baker & Jeukendrup. Optimal composition of fluid replacement beverages. Comp Physiol. 2014;4:575-620.

Burke L. Nutritional needs for exercise in the heat. Comp Biochem Physiol Mol Integr Physiol. 2001; 128: 735-48.

Burke L. Clinical Sports Nutrition, 5th edition. 2015.

Cory M, et al. Resistance training in the heat improves strength in professional rugby athletes. Sci Med in Football. 2019;3:198–204.

Jung A, et al. Influence of Hydration and Electrolyte Supplementation on Incidence and Time to Onset of Exercise-Associated Muscle Cramps. J Athl Train. 2005; 40: 71–75.

Lewis J, et al. Does Hypohydration Really Impair Endurance Performance? Methodological Considerations for Interpreting Hydration Research. Sports Med. 2019;49:103-114.

Nybo & Sawka. Performance in the heat physiological factors of importance for hyperthermia-induced fatigue. Compr Physiol 2014;4:657-89.

Lau W, et al. Effect of oral rehydration solution versus spring water intake during exercise in the heat on muscle cramp susceptibility of young men. J of the Intl Soc of Sp Nutr. 2021; 18 (1).

Amy Stephens