Nutrition- The Overlooked Component of Athletic Performance
For athletes to perform optimally, they need to train hard and fuel their body appropriately.
The food we eat impacts our training, strength, performance, and recovery.
Athletes can perform at a high caliber but may not always be healthy.
Poor nutrition can result in the following:
· Decreased muscle strength
· Decreased glycogen stores
· Depression
· Irritability
· Decreased concentration
· Decreased endurance performance
· Increased injury risk
· Decreased training response
· Impaired judgement
· Decreased coordination
How do you optimize the performance, and more importantly, health of the athlete through nutrition?
The biggest contributor to poor athlete health is under fueling.
Low energy availability forces the body to trigger hormonal responses that adversely affect normal life processes, leading to negative health and performance consequences.
When overall energy deficit is present (caloric intake does not meet energy demands) non-exercise body functions are affected to conserve energy. This will cause an impact on health (amenorrhea, reduced testosterone levels, GI disturbance, impaired immune system) and performance.
When carbohydrate reserve is low, not only are glycogen stores depleted quickly causing fatigue, but protein (mostly from muscle) will be broken down to fuel the body.
Consumption of the appropriate amount of carbohydrates not only spares consumed amino acids from being used as an energy source but also promotes protein synthesis. When carbohydrate stores get depleted, which will occur routinely after moderate to high intensity exercise, and are not replaced, protein will be mobilized to provide fuel for the body. This, ultimately, will lead to a decrease in muscle mass and impair production of other proteins (hormones, enzymes, immune mediators, etc.).
Muscle protein is only preserved, and increased, with adequate carbohydrate (and caloric) consumption.
If protein replaces carbohydrates in the diet, fatigue and decreased performance may occur. Over-consumption of protein can also lead to dehydration and fat weight gain if caloric intake is greater than daily needs.
Macronutrient needs change with age. In the pre-pubescent athlete, a greater focus on healthy fats is desirable for brain development. During puberty and post-puberty into young adulthood, there should be a moderate emphasis on protein due to growth and development. The master athlete also requires higher protein needs to maintain muscle mass.
While all athletes have a greater dependence on carbohydrate consumption for performance, higher intensity sports require an even higher need. For individuals performing 4-5 hours/day of moderate-high intensity exercise, 8-12 g/kg/day of carbohydrate is necessary.
Performance Carbohydrate Needs
Protein needs are also variable based on the type of performance. Endurance athletes are recommended to have 1.4-1.6 g/kg/day while weight class, strength-based athletes need 2.0-2.2 g/kg/day.
While timing of protein intake in athletes is controversial, it appears benefits can be seen pre- and/or post-workout. Protein prior to exercise should be part of a meal containing carbohydrates. While the protein does not provide energy during the workout, it can slow digestion of carbohydrates helping to maintain energy levels, increase satiety, and prevent protein catabolism.
Post-workout protein intake should be soon after the conclusion of the workout to maximize muscle protein synthesis and should be a high-quality source of essential amino acids. The addition of carbohydrates to the post-workout meal/drink will enhance the recovery process.
Research to date, has not shown that protein intake during exercise improves performance on muscle protein synthesis. Most studies have focused on branched chain amino acids since they can be utilized for energy directly within the muscle.
There is data to indicate that females may have decreased absorption and utilization, as well as increased breakdown of protein. All of which results in a higher need for protein, especially post-menopause. Needs for all macronutrients are also dependent on the menstrual cycle.
The primary source of energy at rest and during low to moderate intensity exercise is fat. For overall health, fat needs should be around 1.0 g/kg/day.
There is debate, however, whether a diet higher in fat content during periods of high volume and low-intensity training can maximize fat oxidation. Submaximal, or low, intensity exercise is largely supported by lipids obtained from adipose tissue, intramuscular triacylglycerides (IMTG), cholesterol, and dietary fat. As intensity increases, lipid oxidation decreases, and carbohydrates become the preferred energy source. The point when fat oxidation reaches maximum, and carbohydrate oxidation becomes favored, is termed the maximal fat oxidation (MFO). MFO is reported to occur between 47-75% of VO2max. Improving MFO can result in a significant amount of energy being obtained from available fat stores and prolong exercise performance. Factors that influence the MFO include training level, sex, nutritional intake, as well as exercise intensity and duration.
Premenopausal women have a significantly greater ability to oxidize fat during exercise than men. This difference has been attributed to increased circulation of estrogens. Estrogen promotes increased expression of cellular proteins involved in fatty acid transport and oxidation. Increased fat oxidation has also been shown to improve with endurance training. Trained women can oxidize fat at twice the rate of obese women.
Aerobic training and a fat-rich diet increase the expression of a key enzyme, beta-hydroxy acyl-CoA dehydrogenase, involved in fat oxidation. High fat diets increase IMTG while decreasing glycogen levels within muscle. High fat diets (>68% total daily caloric intake) improve prolonged moderate intensity exercise.
However, while a high fat diet increases fat oxidation, the limitation occurs when high intensity exercise exceeds MFO and carbohydrate metabolism is necessary. Thus, high fat diets can compromise high intensity exercise performance potential if glycogen stores are low due to an increase in IMTG.
High-fat, low-carbohydrate diets have also been shown to increase interleukin-6 (IL-6) in athletes. IL-6 is inflammatory and increases the risk of injury.
On the flip side, an extremely low-fat diet can also be detrimental. Fats are a concentrated source of food energy and play an important immunologic role for athletes. A low-fat diet can increase inflammatory cytokines, negatively affect blood lipoprotein levels, and decrease antioxidant potential. Increased injuries have been seen in female athletes that have a low lipid intake.
The type of dietary fat consumed affects the anti-inflammatory potential. Trans fats, saturated fats, and vegetable oils high in omega-6 fatty acids promote inflammation, whereas monounsaturated and polyunsaturated are found to be anti-inflammatory.
Diets higher in omega-3 fatty acids have been shown to be neuroprotective, promote healing, decrease inflammation, and reduce postexercise delayed-onset muscle soreness. Monounsaturated fats have also been shown to inhibit and reduce inflammation.
Per the Academy of Nutrition & Dietetics, teenage male athletes need 3000-6000 calories per day. Female athletes need between 2200-4000 calories per day.
What health needs should be monitored in athletes?
Sleep
Athletes often need more sleep (8-10 hours/night)
Inadequate sleep is associated with higher injury risk and decreased energy
Decreased total sleep time and sleep efficiency are associated with mental strain and increased training load
Extended sleep time has been found to improve endurance performance
Body resiliency to prevent injury
Emotional resiliency
Digestion surrounding training
Hormonal health
Nutritional sufficiency
Growth
One of the first signs of undernourishment in an athlete is a change in mood.
This is due to delayed glucose availability and/or ability for serotonin turnover. Food creates neurotransmitters, such as serotonin, which alter mood.
Hypoglycemia increases the sympathetic nervous system response resulting in an altered heart rate variability. This impedes recovery and ability to progress with a training program.
Behaviors often seen include increased anxiety and depression. Resulting performance deficits include decreased reaction time, inability to remain in the zone, and poorer coordinated movements.
Consistency with meals/snacks will help keep blood glucose stable for the brain.
The Athlete’s Gut
Almost 85% of athletes have irritable bowel type symptoms (bloating, diarrhea/constipation/cramping).
An under-fueled gut is a weakened gut.
Blood in the stool of athletes is extremely common and due to the intense strain placed on the GI tract.
With training, blood flow moves away from the gut resulting in intestinal permeability leading to increased core temperature, decreased gut integrity, increased heart rate, and poor gut emptying. After injury to the gut, refueling can create worsening symptoms.
Fueling often, fueling with enough carbohydrates, and staying hydrated will help protect the integrity of the gut.
Low Energy Availability and Bone Health
Poor nutrition and low caloric intake are associated with an increase in bone stress and fractures in athletes. This is due to suppression of several hormones including estrogen, testosterone, thyroid, IGF-1, and leptin.
Bone changes seen include decreased bone mineral density, increased inflammation in the bone, and altered bone modeling. This can ultimately result in delayed bone growth.
Several micronutrients, including calcium, vitamin D, magnesium, vitamin K, phosphorous, and potassium, are involved in bone health.
Nutritional Deficits
Athletic training can result in deficiency in several vitamins and minerals including iron and vitamin D. Per athletic standards, a serum ferritin level below 22 ng/ml defines deficiency. Indication for vitamin D deficiency is less than 50 ng/ml serum 25(OH)D.
Calcium, B vitamins, magnesium, potassium, and zinc are also at risk of being deficit. It is estimated that 42% of female athletes have insufficient vitamin D levels and almost 90% are not meeting calcium requirements. Vitamin D is enormously important for our health and athletic performance.
https://www.optin4health.com/blog/vitamin-d-and-its-enormous-importance-for-our-health
HPA-Axis Dysfunction with Nutritional Deficiency
The hypothalamus-pituitary-adrenal (HPA) axis controls our reaction to stress and regulates multiple hormones, as well as various body processes. HPA axis dysfunction can result from chronic low glucose availability. When low energy is sensed, the adrenal glands are instructed to increase cortisol production. If this signaling continues, the adrenal glands will become increasingly stressed resulting in a higher sympathetic response and higher rate of perceived exertion at max heart rate.
In females, the luteinizing hormone (LH) reproductive hormonal surge will decrease, resulting in lower estrogen and cycle abnormality. Low estrogen can also cause a lower resting heart rate and more heart rate variability.
All women of reproductive age, regardless of how much exercise, should have regular menstrual cycles. Menstruation is, thus, a barometer of health in the female athlete. Ovarian hormones not only control the menstrual cycle (and reproduction) but have beneficial effects on the cardiovascular system, the brain, and bone health.
Like menstruation, low testosterone is the barometer for male health. Similar risks, such as, stress fractures, decreased performance, and mood disorders, are seen with lower testosterone levels.
Why do I not feel hungry with training?
Hunger and fullness signaling can become dysfunctional with athletes. Negative feedback within the HPA axis can occur from only a 250-300 calorie disruption in energy availability. This can cause muting of hunger hormones. Energy expenditure from exercise decreases ghrelin (appetite hormone) up to 4 hours post-exercise. Consuming high-volume, low-energy foods may also cause fake fullness.
Immune support
An individual’s nutritional status influences both their susceptibility to infection and their response to infection. Female athletes having low energy availability have been found to have a four to eight times higher risk of upper respiratory infections.
The immune system’s ability to clear viruses, bacteria, and other pathogens, termed ‘resistance’, is dependent upon an adequate supply of energy from important fuel sources, including, glucose, amino acids, and fatty acids. An adequate supply of amino acids is also required to produce proteins such as immunoglobulins, cytokines, and acute-phase proteins. Several micronutrients also directly influence the immune system.
Why is infection incompatible with success in sports?
· Infection is the 2nd most common reason athletes visit their team medic
· Sickness correlates negatively with training volume
· Illness accounts for 1/3 of all lost training days
· 2/3 of illnesses result in time loss for training and competition; 1/3 result in performance restriction
· Heavy exercise can extend an ongoing infection, result in incomplete recovery, and lead to rhabdomyolysis, myopericarditis, and exertional heat stroke
· Medal winners suffer fewer and shorter upper respiratory infections
Common misconceptions in athletes
· Energy drinks or coffee are food
· Carbohydrates are bad
· Fruit will make me fat or has too much sugar
· Eating before bed means I’ll gain weight
· I don’t need snacks between meals
· Sleep is for the weak
· It doesn’t matter what I eat
How to Fuel
All meals should include complex carbohydrates, protein, and healthy fats.
Build a performance plate based upon your training for the day.
On average
Each meal should have 25-30 grams of protein (girls); 30-40 grams (boys)
Each snack should have 10-15 grams of protein
As intensity increases, carbohydrates should increase
Avoid within day energy deficits. Eat every 2-3 hours.
Carbohydrate consumption should be considered prior to and after key high-intensity training sessions and during hard training blocks.
Refuel within 15-30 minutes after activity with carbohydrates and protein. Carbohydrates will not only replenish glycogen stores but will increase protein absorption into muscle tissue.
Late evening snacks are beneficial (especially when caloric needs are extremely high). Pre-sleep protein intake may help with muscle protein synthesis, recovery, and boost morning resting metabolic rate.
Focus on foods high in calcium, iron, magnesium, zinc, and vitamin B6. Increase foods with antioxidant and vasodilating nutrients.
Eat larger portions.
Foods to include are whole grains, peanut butter, granola, fruits, vegetables, avocado, nuts, and soy. Focus on whole foods.
Use fresh herbs and spices in your daily cooking. These precious little gems are powerhouses for fighting oxidative stress and inflammation.
Hydrate!
Dehydration can slow gastric emptying, make regulating body temperature difficult, and potentially cause cardiovascular stress and exercise-induced muscle cramps.
A decrease of blood volume and flow of oxygen to muscles causes a reliance on anaerobic metabolism and buildup of lactic acid sooner.
Hypohydration can affect performance and the ability to rehydrate.
Avoid sugar sweetened beverages and energy drinks.
All meals and snacks matter. Be sure they are balanced and healthy.
Always eat breakfast!
Breakfast eaters are more likely to meet key nutritional needs. Nutrients missed at breakfast are not made up throughout the day.
On high energy requiring days, 2 breakfasts might be beneficial.
Athletes that skip breakfast before resistance training have higher muscle protein breakdown products in their urine.
Consuming breakfast will cause a rise in insulin secretion which suppresses muscle protein breakdown.
Skipping either breakfast or dinner causes an increase in energy expenditure but skipping breakfast alone causes disturbed glucose homeostasis, potentially leading to metabolic inflexibility and low-grade inflammation.
Consuming breakfast has been shown to improve cognitive function in collegiate athletes.
Every athlete should have a personalized, proactive nutritional plan.
Differences exist in specific nutrient needs along the designated spectrum of athletes, and the chosen sport, thus an individualized sports nutrition plan based on current evidence-based guidelines is necessary for success.
The difference between winning and losing is maintaining intensity.
Maintaining intensity= Maintaining nutrition