🏃Exercise Physiology Unit 8 – Nutrition and Exercise Performance

Key Nutritional Concepts

• Nutrient density refers to the amount of nutrients per calorie in a food
  • Foods with high nutrient density provide substantial amounts of vitamins, minerals, and other health-promoting components with relatively few calories (leafy greens, berries)
• Macronutrients are nutrients required in large amounts and include carbohydrates, proteins, and fats
• Micronutrients are essential nutrients required in smaller quantities and include vitamins and minerals
• Energy balance is the relationship between energy intake from food and energy expenditure from physical activity and bodily functions
  • Positive energy balance occurs when intake exceeds expenditure, leading to weight gain
  • Negative energy balance occurs when expenditure exceeds intake, resulting in weight loss
• Basal metabolic rate (BMR) represents the minimum energy required to maintain vital functions at rest
• Thermic effect of food (TEF) is the energy expended above the BMR due to the cost of processing food for storage and use
• Glycemic index (GI) is a measure of how quickly a carbohydrate-containing food raises blood sugar levels
  • Low GI foods (oats, legumes) result in a slower, more sustained release of glucose into the bloodstream

Macronutrients and Exercise

• Carbohydrates are the primary fuel source for high-intensity exercise
  • Adequate carbohydrate intake is crucial for maintaining glycogen stores in the muscles and liver
  • Consuming 6-10 g/kg body weight per day is recommended for athletes engaging in endurance training
• Proteins are essential for muscle repair, growth, and maintenance
  • Athletes require higher protein intake compared to sedentary individuals to support recovery and adaptations
  • Consuming 1.2-2.0 g/kg body weight per day is recommended, depending on the type and intensity of exercise
• Fats play a role in energy provision during low-intensity, long-duration exercise
  • Adequate fat intake is important for overall health, hormone production, and nutrient absorption
  • Consuming 20-35% of total daily energy intake from fats is generally recommended
• Balancing macronutrient intake based on individual goals, training demands, and sport-specific requirements is crucial for optimal performance
• Timing of macronutrient intake around exercise sessions can influence energy levels, recovery, and adaptations
  • Consuming a meal containing carbohydrates and proteins 2-4 hours before exercise can help sustain energy levels
  • Ingesting carbohydrates during prolonged exercise (>60 minutes) can delay fatigue and improve performance

Micronutrients and Athletic Performance

• Vitamin D plays a role in bone health, immune function, and muscle strength
  • Athletes with low vitamin D levels may be at increased risk of stress fractures and upper respiratory tract infections
• Iron is essential for oxygen transport, energy metabolism, and cognitive function
  • Iron deficiency can impair endurance performance and lead to fatigue
  • Female athletes and those engaged in endurance sports are at higher risk of iron deficiency
• Calcium is crucial for bone health and muscle contraction
  • Adequate calcium intake, along with vitamin D, is important for preventing stress fractures and maintaining bone density
• Magnesium is involved in energy production, muscle and nerve function, and bone metabolism
  • Magnesium deficiency can impair exercise performance and increase the risk of muscle cramps
• B vitamins (thiamin, riboflavin, niacin, B6, B12) play key roles in energy metabolism and red blood cell production
  • Adequate B vitamin intake is important for athletes to support energy production and prevent deficiencies
• Zinc is involved in immune function, protein synthesis, and wound healing
  • Zinc deficiency can impair immune response and delay recovery from injury
• Antioxidants (vitamins C and E) help protect cells from oxidative stress induced by intense exercise
  • Adequate intake of antioxidant-rich foods (fruits, vegetables) may support recovery and reduce inflammation

Hydration Strategies

• Maintaining proper hydration is essential for optimal exercise performance and thermoregulation
  • Dehydration can lead to decreased endurance, increased fatigue, and impaired cognitive function
• Athletes should aim to start exercise in a well-hydrated state
  • Consuming 5-10 ml/kg body weight of fluid 2-4 hours before exercise can help ensure adequate hydration
• Monitoring hydration status through urine color and body weight changes can help guide fluid intake
  • Pale yellow urine indicates adequate hydration, while dark yellow or amber urine suggests dehydration
• During exercise, athletes should aim to replace fluid losses to maintain hydration
  • Consuming 150-250 ml of fluid every 15-20 minutes during exercise can help prevent dehydration
  • Sports drinks containing carbohydrates and electrolytes can be beneficial for exercise lasting longer than 60 minutes
• Post-exercise rehydration should aim to replace fluid and electrolyte losses
  • Consuming 1.5 L of fluid per kg of body weight lost during exercise can help restore hydration status
  • Including sodium in post-exercise fluids can enhance fluid retention and promote rehydration
• Individual sweat rates and sodium losses vary, so personalized hydration plans may be necessary
  • Sweat rate can be estimated by measuring body weight before and after exercise in different conditions

Pre-Exercise Nutrition

• Consuming a pre-exercise meal 2-4 hours before training or competition can help optimize energy levels and performance
  • The meal should contain easily digestible carbohydrates to top off glycogen stores and provide sustained energy
  • Including a moderate amount of protein can help reduce muscle damage and promote recovery
• Timing and composition of the pre-exercise meal should be individualized based on personal preferences and digestive tolerance
  • Athletes may need to experiment with different food choices and timing to find what works best for them
• Consuming a small snack 30-60 minutes before exercise can provide additional energy without causing gastrointestinal discomfort
  • Examples include a banana, energy bar, or sports drink
• Hydration status should be optimized before exercise by consuming fluids in the hours leading up to the session
  • Aim for pale yellow urine color as an indicator of adequate hydration
• Caffeine consumption 30-90 minutes before exercise may enhance performance, particularly for endurance activities
  • Doses of 3-6 mg/kg body weight have been shown to be effective
  • Individual responses to caffeine vary, so athletes should experiment during training to assess tolerance and benefits

During-Exercise Fueling

• Consuming carbohydrates during exercise lasting longer than 60 minutes can help maintain blood glucose levels and delay fatigue
  • Aim for 30-60 g of carbohydrates per hour, depending on the intensity and duration of the activity
  • Sources of carbohydrates include sports drinks, gels, chews, or easily digestible foods (ripe bananas, honey)
• Combining different types of carbohydrates (glucose, fructose) can increase absorption and reduce gastrointestinal discomfort
  • Sports drinks often contain a mix of carbohydrates to optimize uptake and energy provision
• Fluid intake during exercise is crucial to replace sweat losses and maintain hydration
  • Aim to consume 150-250 ml of fluid every 15-20 minutes, depending on sweat rate and environmental conditions
  • Sports drinks containing electrolytes (sodium, potassium) can help replace losses and promote fluid retention
• Practicing fueling strategies during training sessions is important to assess tolerance and optimize performance
  • Athletes should experiment with different products, flavors, and timing to find what works best for them
• For ultra-endurance events lasting several hours, including protein and fat sources may help support energy needs and reduce muscle breakdown
  • Examples include nut butters, trail mix, or protein-rich energy bars

Post-Exercise Recovery Nutrition

• Consuming a combination of carbohydrates and protein after exercise can help replenish glycogen stores, promote muscle repair, and reduce soreness
  • Aim for a carbohydrate-to-protein ratio of 3:1 or 4:1 for optimal recovery
  • Examples include chocolate milk, a turkey sandwich, or a smoothie with fruit and protein powder
• Timing of the post-exercise meal or snack is crucial for maximizing recovery benefits
  • Consuming nutrients within 30-60 minutes after exercise can take advantage of the "anabolic window" when the body is primed for nutrient uptake
• Adequate fluid and electrolyte intake after exercise is important for rehydration and replacing sweat losses
  • Consuming 1.5 L of fluid per kg of body weight lost during exercise can help restore hydration status
  • Including sodium in post-exercise fluids can enhance fluid retention and promote rehydration
• Antioxidant-rich foods (berries, leafy greens) and omega-3 fatty acids (fatty fish, walnuts) may help reduce inflammation and support recovery
  • Incorporating these nutrients into the overall diet can provide long-term benefits for athletic performance and health
• Rest and sleep are essential components of the recovery process, allowing the body to adapt to training stressors
  • Aiming for 7-9 hours of quality sleep per night can optimize recovery and support overall health

Nutrition for Different Types of Exercise

• Endurance exercise (running, cycling, swimming) primarily relies on carbohydrates and fats for fuel
  • Higher carbohydrate intake (6-10 g/kg body weight per day) is recommended to support training and performance
  • Consuming carbohydrates during prolonged exercise (>60 minutes) can delay fatigue and improve performance
• Resistance exercise (weightlifting, bodyweight training) places greater emphasis on protein for muscle repair and growth
  • Consuming 1.6-2.0 g/kg body weight of protein per day, spread evenly throughout the day, can support muscle adaptations
  • Including a source of protein (20-40 g) in the post-exercise meal can maximize muscle protein synthesis
• High-intensity interval training (HIIT) involves short bursts of intense exercise followed by periods of rest or low-intensity activity
  • Adequate carbohydrate intake (5-7 g/kg body weight per day) is important to fuel high-intensity efforts
  • Consuming a mix of carbohydrates and protein after HIIT sessions can support recovery and adaptations
• Team sports (soccer, basketball, hockey) require a combination of endurance, strength, and power
  • Carbohydrate intake should be tailored to match the demands of training and competition (5-7 g/kg body weight per day)
  • Adequate protein intake (1.4-2.0 g/kg body weight per day) is important for muscle repair and recovery
• Skill-based sports (golf, archery, shooting) may have lower energy demands but still require focus on overall nutrition for health and performance
  • Maintaining stable blood sugar levels through regular, balanced meals can support concentration and skill execution
  • Adequate hydration is important for maintaining cognitive function and reducing the risk of fatigue

Supplements and Ergogenic Aids

• Creatine is one of the most well-researched and effective supplements for improving strength and power performance
  • Supplementing with 3-5 g per day can increase muscle creatine stores and enhance short-term, high-intensity exercise capacity
  • Creatine has also been shown to support muscle growth and recovery when combined with resistance training
• Caffeine is a popular ergogenic aid that can improve endurance performance, reduce perceived exertion, and enhance mental alertness
  • Doses of 3-6 mg/kg body weight consumed 30-90 minutes before exercise have been shown to be effective
  • Individual responses to caffeine vary, so athletes should experiment to assess tolerance and benefits
• Beta-alanine is an amino acid that can increase muscle carnosine levels, which may improve high-intensity exercise performance
  • Supplementing with 4-6 g per day for at least 2-4 weeks has been shown to be effective
  • Beta-alanine supplementation may cause a harmless tingling sensation (paresthesia) in some individuals
• Nitrate, found in beetroot juice and leafy greens, can improve endurance performance by reducing the oxygen cost of exercise
  • Consuming 300-500 mg of nitrate, 2-3 hours before exercise, has been shown to enhance performance
  • The ergogenic effects of nitrate may be more pronounced in untrained or moderately-trained individuals
• Protein powders (whey, casein, plant-based) can be a convenient way to meet protein needs, especially for athletes with high requirements
  • Consuming protein supplements as part of a balanced diet can support muscle recovery and growth
  • Protein quality, digestibility, and amino acid profile should be considered when selecting a protein powder
• While supplements can provide performance benefits, they should not be relied upon as a substitute for a well-planned nutrition strategy
  • Athletes should prioritize a balanced diet, adequate hydration, and proper recovery practices before considering supplement use
  • Consulting with a sports nutritionist or registered dietitian can help guide safe and effective supplement use based on individual needs and goals