- A Brief Review of the History and Physiology of Endurance Exercise
- The Physiology of Endurance Exercise
- Optimal Foods for an Endurance-Focused Ancestral Diet
- The Benefits of an Ancestral Diet for Endurance Athletes
- Macronutrients for Endurance Athletes
- Meal and Macronutrient Timing for Endurance Athletes
- Nutrition for Female Endurance Athletes
- Vegan and Vegetarian Diets and Endurance Sports
- Endurance Athletes on Ketogenic Diets
- Troubleshooting Common Problems in Endurance Athletes with Nutrition
- In Summary
An ancestral diet rich in whole, nutrient-dense, anti-inflammatory foods is an excellent nutritional framework for most individuals. But, can it stand up to the task of fueling endurance athletes? For decades, endurance athletes have been encouraged to fuel with processed, refined carbs and artificial chemical-laden energy gels, among other ingredients. However, a growing body of research (and clinical experience) indicates that whole, nutrient-dense foods can optimally fuel endurance athletes. Read on to learn how an ancestral diet can properly fuel endurance athletes, supporting better performance, enhanced recovery, and whole-body health.
A Brief Review of the History and Physiology of Endurance Exercise
Are human beings “wired” for endurance activity? Findings from the field of evolutionary biology certainly seem to suggest so! Professor Dan Lieberman of Harvard has dedicated his career to the study of the evolution of the human body, including the profound role that running may have played in the “evolution of the human body form.” (1) Long-distance running may have enabled our hominid ancestors to chase down herbivores (i.e., prey) to exhaustion, allowing meat to more consistently become a part of our diets. Evolutionary biologists such as Richard Wrangham, in turn, propose that meat consumption accelerated our brain development by providing us with highly bioavailable energy and critical nutrients for brain growth and development, such as iron, zinc, nicotinamide (vitamin B3), vitamin B12, and dietary cholesterol. (2) Walking, but perhaps not running, long distances also allowed our ancestors to forage crucial plant foods. In other words, our evolved capacity to engage in endurance activity in the name of food procurement may have allowed us to become the highly intelligent, advanced creatures we are today.
Today, most of us don’t need to run down prey to eat dinner, but some of us still engage in endurance exercise for enjoyment. In truth, our bodies are evolutionarily no different from our early hunter–gatherer ancestors’ bodies; our bodies are still “wired” to expect a certain quantity of physical activity each day.
The Physiology of Endurance Exercise
Endurance exercise relies primarily on the body’s aerobic system to provide energy for fueling activity. Examples of endurance exercises include cycling, running, hiking, backpacking, cross-country skiing, and rowing, among other activities.
Adenosine triphosphate (ATP) is the short-term energy storage molecule that fuels your muscle cells. Energy is released when the chemical bonds of ATP are broken. This chemical energy fuels life itself. The rate at which ATP is created limits both speed and the ability to sustain endurance activity.
The ability to engage in endurance activity lasting less than two hours hinges on the rate at which muscle cells can sustainably produce energy to drive muscular contractions. The ability to fuel endurance activities that last longer than two hours depends primarily on the body’s energy stores in the form of glycogen, a form of stored carbohydrate that resides in the liver, muscles, and body fat. These storage forms of energy can be broken down to create ATP. ATP availability is essential for endurance performance.
The carbohydrate, protein, and fat we eat in our diets must be broken down into sugars, amino acids, and fatty acids to support our bodies’ various functions. There are two pathways in the mitochondria, the “energy powerhouses” of your cells, by which sugars and fatty acids are metabolized to create ATP:
- The anaerobic glycolysis pathway: This is how glucose, derived mainly from dietary carbohydrates, is processed to produce ATP. Anaerobic glycolysis does not require oxygen and is used to fuel activity where the ATP demand is high, such as sprinting or high-intensity interval training.
- Aerobic metabolism: The aerobic metabolic pathway uses pyruvate, a product of the anaerobic glycolysis pathway, and fatty acids to produce ATP. Think of this pathway as an extension of the anaerobic glycolysis pathway that produces far more ATP than anaerobic glycolysis alone but functions at a slower rate. Aerobic metabolism largely fuels longer-duration, less intense physical activity.
Note that these systems run simultaneously; it is the relative contribution of anaerobic vs. aerobic metabolism that differs at different exercise intensities.
Relying heavily on carbohydrates to fuel endurance activity places a significant demand on anaerobic glycolysis; the problem is that anaerobic glycolysis produces a metabolite called lactate. Lactate is a normal product of glycolytic metabolism, but it builds up throughout an endurance exercise session. The lactate buildup increases the cell’s acidity, impairing muscular contraction; it also inhibits glycolysis, reducing ATP production. While lactate production is ultimately inevitable at specific speeds and intensities of exercise, the longer we can rely on our aerobic metabolism to fuel endurance activity rather than anaerobic metabolism, the longer we can sustain ATP production inside our cells.
Cells can use lactate for energy production by recycling lactate back to glucose, so lactate is not just a waste product; better-trained athletes have lower blood lactate levels because they have an enhanced lactate clearance. But eventually, everyone reaches the “lactate threshold”—the exercise intensity at which the blood concentration of lactate increases more rapidly than it can be removed. This threshold is the best predictor of endurance performance. A higher lactate threshold enables athletes, whether professional or recreational, to engage in activity for longer without “bonking.”
An ancestral dietary approach may be beneficial, alongside proper training, for endurance athletes because it reduces dependence on carbohydrates and helps the body adapt to using fat to fuel aerobic metabolism. However, this is just one reason why an ancestral nutrition approach is beneficial for endurance activity. Read on to learn the reasons why an ancestral diet is the optimal nutritional template for endurance athletes.
Are you an endurance athlete? Eating an ancestral diet may optimize your performance, recovery, and overall health. Read this article by nutritionist Linsay Christensen for more on the benefits of an ancestral diet for endurance athletes. #nutrition #optimalhealth #wellness
Optimal Foods for an Endurance-Focused Ancestral Diet
An ancestral diet for endurance athletes should be centered around the following foods:
- Protein: From a biochemical perspective, animal protein is more bioavailable than plant protein; this fact may be crucial for endurance athletes, who place significant demands on their musculature to perform their respective sports. Meat, poultry, seafood, eggs, and dairy products, in those who tolerate them, represent ideal dietary protein sources for endurance athletes.
- Carbohydrates: An ancestral diet emphasizes cellular carbohydrates or foods that contain carbohydrates within plant cell walls. These foods have a lower carbohydrate density and may support balanced blood sugar control and healthier gut microbiota. However, there’s also a time and place for denser whole-food-based carbs for endurance athletes, such as white rice, long-fermented sourdough, properly prepared legumes (legumes that have been soaked thoroughly before cooking), or gluten-free grains to replenish glycogen stores, and/or natural sugars such as honey or dates to fuel high-intensity exercise. The amount of carbohydrate an endurance athlete—recreational or professional—requires for optimal performance is best determined with the help of a dietitian or nutritionist.
- Fat: Healthy fats, including olive oil, coconut oil, avocado oil, butter, ghee, avocados, olives, nuts, seeds, and fatty cold-water fish, provide anti-inflammatory fats for supporting hormone production and exercise recovery. Full-fat, organic, or grass-fed dairy products may also serve as a source of healthy fats for those athletes who tolerate them.
- Non-starchy vegetables: Non-starchy vegetables, such as broccoli, kale, mushrooms, and bell peppers, may not be energy-dense, but they do provide dietary fiber, micronutrients, and phytonutrients for dampening inflammation and supporting the gut microbiota, which, as we’ll learn, can be significantly impacted by endurance exercise.
The Benefits of an Ancestral Diet for Endurance Athletes
An ancestral diet is an optimal eating strategy for endurance athletes for four primary reasons:
- It supports gut health, which can become compromised by endurance exercise.
- It is anti-inflammatory and thus attenuates inflammation triggered by exercise.
- It provides essential nutrients for endurance exercise performance and recovery.
- It promotes fat-adaptation, allowing endurance athletes to become more metabolically efficient.
Let’s discuss each of the benefits of an ancestral diet template for endurance athletes in turn:
1. Supports Gut Health
While moderate physical activity, such as endurance exercise, may support gut health over the long term, increasing microbial diversity and reducing the risk of diseases such as colon cancer (3, 4), higher levels of intensities of endurance exercise, such as those engaged in by endurance athletes, can elicit gastrointestinal (GI) issues. Alterations in gut function in endurance athletes are caused by redirecting blood flow away from the gut to the working skeletal muscles and peripheral circulation; this reduces oxygen delivery to the gut. This process, referred to as “splanchnic hypoperfusion,” damages tight junction proteins that join intestinal cells, increasing permeability, or “leaky gut.” (5, 6)
While the exact exercise threshold at which leaky gut is induced may differ from one individual to the next, higher intensities and longer distances may be more likely to elicit this response, based on research showing that 60 minutes of vigorous endurance training at 70 percent of the VO2 max (maximal oxygen consumption) led to increased intestinal permeability. (7) High-intensity endurance activity, particularly running, may also degrade the gut’s mucus barrier, increasing athletes’ susceptibility to bacterial endotoxemia, a “leakage” of pro-inflammatory bacterial byproducts from the intestinal lumen into the systemic circulation, subsequently eliciting chronic inflammation. (8)
The acute intestinal permeability elicited by exercise may be exacerbated by other factors known to increase intestinal permeability, such as an unhealthy Standard American Diet (SAD). (9)
An ancestral diet removes SAD foods, such as processed foods, gluten, and industrial seed oils, that contribute to intestinal permeability. It also minimizes antinutrients that increase intestinal barrier permeability, such as lectins and saponins. An ancestral diet also provides the necessary nutrients to support a robust intestinal barrier and healthy gut microbiota, including vitamin A, zinc, phytochemicals, prebiotic dietary fibers, and probiotic cultures from fermented foods.
2. Minimizes Inflammation
Moderate-intensity endurance exercise triggers a short-term increase in inflammation that ultimately causes the body to “bounce back” less inflamed than before—a process referred to as “hormesis.” However, high-intensity, frequent, and long-duration endurance activity can increase inflammation over time. (10) While an appropriate training load and adequate recovery time are crucial for reducing inflammation, diet also plays a significant role. Eating a SAD adds insult to injury by exacerbating systemic inflammation, while an ancestral diet centered around whole, anti-inflammatory foods reduces inflammation, facilitating recovery and performance. (11, 12) Removing dietary inflammatory triggers with an ancestral diet may help the body adapt to and recover better from endurance exercise.
Importantly, it may be wise to avoid supplemental antioxidants, such as vitamin C, after exercise because the antioxidants may hinder that acute adaptive inflammatory response to the exercise. (13) However, there is no evidence that eating whole foods that contain antioxidants hinders exercise adaptation or performance.
3. Provides Essential Nutrients for Performance and Recovery
An ancestral diet is nutrient-dense and supplies critical micronutrients necessary for fueling exercise and supporting maintenance and adaptation to endurance exercise. While numerous micronutrients are found in an ancestral diet that facilitate endurance performance, I want to highlight a few here:
Branched-Chain Amino Acids
Branched-chain amino acids (BCAA) comprise the amino acids (protein building blocks) leucine, isoleucine, and valine. BCAA are essential nutrients that support muscle protein synthesis, helping the body adapt to exercise. While BCAA can be supplemented, they are naturally abundant in meat and dairy products. These animal proteins are a central part of an omnivorous ancestral diet.
Endurance athletes should pay particular attention to their intakes of zinc, a trace mineral necessary for hormone production, immune function, and muscle growth and repair in response to exercise. (14, 15) Zinc is lost through sweat, so endurance athletes who are heavy sweaters may be particularly at risk for zinc insufficiency. (16) Animal foods, a central part of an ancestral diet, are the most bioavailable sources of dietary zinc. Red meat, poultry, and oysters are excellent sources. While whole grains and legumes also contain zinc, they are high in antinutrients, such as phytic acid, that bind to zinc and inhibit its absorption.
Magnesium deficiency is one of the most common nutritional deficiencies and one of the most crucial minerals for endurance athletes. During long-duration endurance exercise, magnesium translocates from blood serum to red blood cells and muscles to support movement. It supports mitochondrial energy production, nerve conduction, muscle contraction, and protein synthesis. Magnesium deficiency may impair muscle contraction and relaxation and cardiorespiratory fitness. (17) The most bioavailable dietary sources of magnesium include dark leafy greens, avocado, potato, banana, almonds, cashews, broccoli, and salmon.
Iron is an essential micronutrient for everyone, but it is vital for endurance athletes. It is an intrinsic component of heme, cytochromes, and myoglobin, which are all involved in fueling muscle cells. Endurance exercise increases blood volume and necessitates more red blood cells for carrying iron to tissues. Furthermore, a phenomenon called “foot strike hemolysis” may increase red blood cell destruction, necessitating the intake of more iron-rich foods to replace the destroyed red blood cells. (18)
Insufficient iron intake reduces red blood cell production, impairs the body’s oxygen-carrying capacity, impacts oxygen delivery to muscles, and can compromise endurance performance. (19) Low levels of iron in endurance athletes may also cause fatigue, poor recovery from exercise, and a low mood. Chronic dietary iron deficiency can cause anemia, a lack of iron in the blood. However, iron insufficiency can also compromise exercise performance in the absence of frank iron deficiency anemia. Low ferritin but a normal hemoglobin level in blood work can indicate iron deficiency without anemia. Menstruating female endurance athletes and vegan and vegetarian endurance athletes are more likely to suffer from iron deficiency due to increased iron loss through the menses and lower dietary iron intakes, respectively.
An ancestral diet that contains balanced amounts of red meat, poultry, seafood, and organ meats provides plentiful dietary iron. Heme iron, found in animal foods such as red meat and poultry, is extremely beneficial for endurance athletes because it is significantly more bioavailable than non-heme iron found in plant foods. Up to 25 percent of heme iron is absorbed from foods, whereas only 3 to 15 percent of non-heme iron is absorbed. Beef liver, one of the foods we encourage most frequently in an ancestral diet, is an excellent source of heme iron for athletes, with 3 ounces providing 6 mg of iron.
Iron absorption by the gut is impaired after exercise due to a transient increase in hepcidin. This protein influences iron uptake by enterocytes (cells in the gut). Hepcidin may be increased for three to six hours post-exercise, so your most iron-rich meal of the day should ideally occur outside of this timeframe. (20) Avoid consuming iron-rich foods simultaneously with calcium-rich foods (such as dairy products), tannin-rich foods (such as tea and coffee), and high-fiber foods, since calcium, tannins, and fiber can inhibit iron absorption in the gut.
Endurance athletes may have a higher dietary need for vitamin B12 compared to non-athletes. Vitamin B12 is essential for red blood cell synthesis and succinyl-CoA formation, an intermediate in mitochondrial ATP synthesis. Vitamin B12, along with vitamin B9 (folate), is also involved in methylation pathways that produce numerous compounds involved in exercise metabolism, including catecholamines and creatine. Low vitamin B12 intake, or poor B12 absorption due to GI inflammation or dysbiosis, can compromise endurance exercise performance by lowering red blood cell production (and thus the oxygen-carrying capacity of the blood) and impairing ATP production. Together, these effects may lead to fatigue and poor recovery from exercise. Vitamin B12 is found almost exclusively in animal foods such as red meat, poultry, seafood, and eggs.
4. Promotes Fat Adaptation
Last but not least, an ancestral diet minimizes processed, refined carbohydrates, which spike blood glucose and insulin and cause the body to become reliant on carbohydrates for fuel. Chronic consumption of refined carbohydrates, as many endurance athletes have been apt to do for decades, reduces the ability to burn fat for energy and leads to the excessive production of lactate, which acidifies muscle and reduces performance. By reducing your intake of refined carbohydrates and relying instead on balanced proportions of cellular carbs (carbohydrates contained within plant cell walls), protein, and healthy fats, athletes on an ancestral diet may be able to better access fat for fuel, reducing lactate accumulation and improving performance.
Macronutrients for Endurance Athletes
The macronutrient needs of endurance athletes vary depending on sex, age, and training volume. However, there are a few rules of thumb endurance athletes should remember:
Conventional sports nutrition wisdom has long recommended a high-carb diet for endurance athletes. Recommendations to consume 5 to 8 g of carbs/kg of body weight per day (which translates to 272 to 435 g of carbs per day for a 120 lb female!) have been the standard. However, a growing body of research indicates that such a high carb intake may not be ideal for long-term health (21), just as we’ve learned that the SAD carb recommendation may not be beneficial for metabolic health or your body weight.
A moderate- to high-carb intake may work best for female endurance athletes. Females tend to be more sensitive hormonally to carbohydrate restriction, particularly when the carb restriction is combined with demanding physical activity. Male endurance athletes, on the other hand, may thrive on low-, moderate-, or high-carb approaches.
Good sources of carbohydrates for athletes on an ancestral diet include sweet potatoes, white potatoes, cassava, plantains, white rice, and fruit. These carb sources are low in antinutrients (such as phytic acid), support balanced blood sugar levels, and support a healthy gut. Some endurance athletes may also do well with other gluten-free grains, such as oats, buckwheat, and quinoa, and legumes.
A protein intake that comprises 20 to 25 percent of total daily calories is ideal for most endurance athletes; alternately, you can aim for 1.5 to 2.0 g of protein/kg of body weight per day. A nutritionist or dietitian can help you further fine-tune your daily protein needs. Protein consumption post-endurance exercise is crucial for supporting muscular adaptation to exercise; an intake of 30 g of protein post-endurance activity has been found to maximize skeletal muscle myofibrillar and mitochondrial protein synthesis in young men. (22) Women may tolerate consuming slightly less protein, between 20 to 30 g, post-exercise. Red meat, poultry, seafood, eggs, and dairy products provide the most bioavailable protein sources for humans. The proteins in grains and legumes are far less bioavailable.
Endurance athletes should consume various healthy fats, including olive oil, coconut oil, butter, ghee, nuts, seeds, and fatty cold-water fish. Avoidance of industrial seed oils, such as canola, corn, cottonseed, grapeseed, safflower, soybean, sunflower, peanut, and rice bran oils, is recommended to keep inflammation at a minimum.
Water serves crucial functions for the exercising body, including lubricating organs and joints and acting as a solvent to transport molecules, such as glucose and micronutrients, throughout the body.
The amount of water needed by endurance athletes depends on sex, body size, the intensity and duration of the workout, the ambient temperature, chronological age, and how much you sweat. Failing to meet your hydration needs reduces the body’s ability to utilize oxygen efficiently to perform exercise, hastens the onset of fatigue, and increases an individual’s risk of experiencing heat-related issues when exercising in a warm environment.
As for sodium replenishment, the American College of Sports Medicine recommends that athletes replete their bodies with approximately 300 to 600 mg of sodium per hour (1.7 to 2.9 g salt) during exercise sessions lasting longer than an hour. (23)
A good rule of thumb is to drink 4 to 6 cups of water in the two hours leading up to an exercise session. Weighing the body before and after an exercise session can provide insight into how much body water was lost; the recommendation is to consume 1 L of fluid for every kg (2.2 lb) of body water lost after exercise.
Meal and Macronutrient Timing for Endurance Athletes
The timing of meals and macronutrient intakes for endurance athletes depends on the type of workout or competition the athlete is engaging in. For routine training, females should always enter a workout with some “fuel in the tank.” If training is being completed early in the morning, consuming at least 150 calories of food before the workout to avoid triggering hypothalamic–pituitary–adrenal (HPA) axis dysfunction, followed by a complete meal balanced in protein, carbs, and fat after the workout, is ideal.
Men who engage in training early in the morning may be able to go into a workout fasted a couple of days per week (this is referred to as a “train low” strategy). Periodically training in a low-carbohydrate availability state may bolster the “molecular machinery” involved in regulating beneficial adaptations to exercise training. (24) However, this “train low” strategy should not be carried over into all training sessions or competitions. Furthermore, it is not clear whether women benefit from the “train low” strategy; at this time, I advise against it since women’s hormonal milieus are sensitive and tend to respond adversely to this approach.
Nutrition for Female Endurance Athletes
Special considerations need to be made for female endurance athletes because estrogen and progesterone, the predominant female sex hormones, significantly influence many parameters of endurance performance. Estrogen and progesterone levels, which vary throughout a woman’s menstrual cycle, influence whether carbs or fats are utilized more efficiently for fuel as well as fluid balance, bone density, and cardiovascular function.
When estrogen is high before ovulation and during the mid-luteal phase of the menstrual cycle, women’s ability to use fat for fuel is enhanced. Low- to moderate-intensity endurance exercise may be ideal for women at these points in the cycle since fat is readily burned for energy at low to moderate intensities. (25) However, suppose a woman wants to engage in higher-intensity endurance exercise at these times. In that case, she may want to supplement her diet with extra carbohydrates to provide her body with the fuel it needs to perform well anaerobically.
Female endurance athletes also need to be cognizant of their protein intake, as their bodies are more subject to catabolism after endurance activity. An intake of 1.5 to 2.0 g of protein/kg of body weight per day is an ideal target for women. In the hour after completing an endurance training session, premenopausal women should consume at least 0.32 to 0.38 g of protein/kg of body weight. (26) Optimizing protein intake is particularly crucial during the luteal phase when the female body is more catabolic (more prone to the breakdown of muscle tissue).
Vegan and Vegetarian Diets and Endurance Sports
While there are endurance athletes who appear to be thriving on a vegan or vegetarian diet, such as ultra-endurance athlete Rich Roll, these athletes may be the exception rather than the rule regarding endurance athletic performance on such diets. Vegetarian diets tend to be lower in protein, fat, vitamin B12, riboflavin, vitamin D, calcium, iron, and zinc than omnivorous diets. (27) Vegan recreational runners have been found to have lower intakes of total calories, protein, vitamin D, and selenium compared to non-vegan runners. (28) Insufficient intakes of these nutrients increase the risk of injury, fatigue, and anemia, just to name a few effects. Research suggests that “well-planned” vegetarian and vegan diets can support recreational runners; however, note the operative term “well-planned.” (29) According to the authors, a “well-planned” vegan or vegetarian diet for endurance athletes necessitates supplements, particularly supplemental vitamin B12, vitamin D, and iron.
Vegan and vegetarian athletes also have lower intakes of leucine, an anabolic amino acid crucial for muscle protein synthesis. (30) They may also be more susceptible to relative energy deficiency in sport (RED-S)—see more on this below. The increased risk of RED-S in vegan and vegetarian athletes may be caused partly by the high fiber content of their diets, which induces early satiety and can reduce overall energy intake.
Endurance Athletes on Ketogenic Diets
Several endurance athletes have made headlines for their very-low-carb (keto) diets, such as ultra-runner Zach Bitter. (31) While preliminary research suggests that a ketogenic diet may improve specific performance parameters, such as VO2 max and time to exhaustion, the jury is still out as to whether this approach improves performance over the long term in larger populations. (32) It is also important to note that ketogenic diets have not been studied in female endurance athletes; I do not recommend ketogenic diets to female endurance athletes for many reasons, including the potential of the diet to disrupt hormones. In my opinion, women engaged in endurance sports, in particular, should avoid low-carb and keto diets.
Interestingly, endurance athletes concerned about their iron levels may want to forgo a low-carb, high-fat dietary approach. Doing endurance training frequently in a low-carbohydrate availability state may promote sustained elevations in hepcidin, which compromises intestinal iron absorption. (33)
Troubleshooting Common Problems in Endurance Athletes with Nutrition
Endurance athletes are not unfamiliar with GI issues, including diarrhea, bloating, and urgency. Research indicates that some of these GI issues may be related to a sensitivity to dietary FODMAPs. (34) FODMAPs are a group of dietary carbohydrates that are poorly absorbed in the gut and can be fermented by gut bacteria, leading to the production of gases that cause GI symptoms. Reducing dietary FODMAP intake before and during exercise sessions can minimize GI symptoms.
GI issues in endurance athletes may also be related to intakes of sports gels, which have an osmotic effect (drawing water into the intestine) and can disrupt the gut microbiota. Avoid processed sugary sports gels, “beans,” and other sugary fueling strategies; many of these products contain maltodextrin, which disrupts the gut microbiota and compromises intestinal immune defenses against harmful microbes. (35)
For quick carbohydrate-based energy during endurance exercise, athletes can use whole, unprocessed foods such as raw honey or dates instead. Spring Energy, which combines a base of white Basmati rice with other whole-food ingredients to create a “real food” energy gel, is another good option. Alternately, they can fuel with medium-chain triglyceride (MCT) oil (which elicits ketone production) or essential amino acids (EAA) instead; these two substrates can be used to fuel activity and, in the case of EAA, reduce fatigue by supplying amino acids for the creation of neurotransmitters.
Nutrition has multidimensional effects on the prevention and treatment of injuries in endurance athletes. For example, an optimal protein intake is crucial not only for preventing muscle injuries but also for rehabilitation from existing injuries. An ancestral diet that emphasizes an adequate intake of bioavailable protein may help prevent and support injuries. Vitamin D deficiency impairs muscle regeneration following exercise and may thus predispose athletes to injuries. (36)
Gelatin and collagen may help treat tendon and ligament injuries, and an ancestral diet that includes “nose-to-tail” eating includes plenty of collagen and gelatin! Gelatin and collagen are rich in glycine, proline, hydroxylysine, and hydroxyproline, which support healthy connective tissue. Collagen consumption has been found to support muscle tissue recovery after demanding exercise. (37) To support recovery from injury, try adding more collagenous cuts of meat, such as brisket and oxtail, as well as grass-fed gelatin or collagen peptides to your diet.
Excess inflammatory foods, calorie insufficiency, and a host of other nutritional factors may predispose individuals to, and affect recovery from, injuries. A qualified nutritionist or dietitian can help you identify which nutritional factors you may need to address to reduce your chances of injury or recover from an existing injury.
As I mentioned earlier, RED-S is a relative deficiency of calorie intake in relation to energy expenditure through exercise in athletes that may or may not be accompanied by disordered eating behaviors. (38) Females may experience amenorrhea, a loss of their period, and decreased bone mineral density. Males can also experience RED-S; some symptoms of RED-S in men include decreased muscle strength, mood changes, reduced libido, and compromised sleep.
Recovery from RED-S necessitates supplying the body with sufficient calories and decreasing energy expenditure through exercise. I would argue that dietary nutrient density, not just dietary calorie density, is also crucial for supporting recovery from RED-S.
Stress fractures are not uncommon in endurance athletes but are highly preventable. Risk factors for stress fractures in female endurance athletes include relative energy deficiency (discussed above), menstrual dysfunction (which lowers levels of estrogen, a crucial bone-building hormone), and excessive exercise. In both male and female athletes with stress fractures, protein, calcium, vitamin D, and magnesium deficiencies may also be at play. (39)
It makes sense that an ancestral diet would be ideal to fuel a vital evolutionary skill like long-distance running. It provides the essential nutrients your body needs to work at optimal capacity while at the same time avoiding the inflammation of highly processed foods. So what has your experience been with endurance exercise and a nutrient-dense diet? Have you struggled? Or have you found success?