Hot Topics/ Research/ Healthy Diet / Measuring Energy
What is the best approach to scrutinize sports nutrition claims?
Develop skills to critically evaluate sports nutrition claims and substantiate or refute them with evidence.
Explain the fate(s) of lactate
if lactate concentrations get too high, lactate is converted to pyruvate (Cori Cycle/ Gluconeogenesis) and taken into the mitochondria of highly aerobic cells. Once inside the mitochondria, this compound is metabolized aerobically
What CHO recommendations post-exercise?
first hour?
up to 4 hours?
1-1.5 g/kg body weight in first hour
1-1.2 g/kg each hour for up to 4 hours
What are BCAAS? Does supplementation work?
Leucine, isoleucine, valine
studies show promise for immune system support, cognition and reduction of postexercise fatigue lower serotonin by competing with its precursor tryptophan for crossing the BBB)
How do SCFA and LCFA vary in their absorption?
Does MCT oil increase fat burning?
1.SCFA and MCFA uptake by enterocytes do not require FA transporters, but LCFA require fatty acid transport proteins (FAT/ CD36, FABP)
MCT oil showed very little to no ergogenic effects on exercise performance and substrate utilization in healthy populations
Sports Nutrition can be defined as?
What are the short and long term goals?
The integration and application of scientifically based principles to support and enhance training, performance, and recovery
Short term goals -
•Consumption of food and beverages to delay fatigue during training and competition
•Minimization of dehydration and hypohydration
•Utilization of dietary strategies beneficial for performance, such as precompetition meal, appropriately timed caffeine intake, or carbohydrate loading
•Intake of nutrients that support recovery
•Appropriate timing of nutrients
Long term goals - Adequate overall diet to maintain good health and support a healthy immune system; Adequate replenishment of muscle and liver glycogen with dietary carbohydrates; Adequate protein intake for growth and repair of tissue, particularly skeletal muscle
How does creatine supplementation assist with the phosphagen system? Explain the creatine shuttle.
•Increases creatine and phosphocreatine concentrations
The creatine shuttle Rephosphorylation of creatine phosphate from creatine via aerobic metabolism. Creatine that remains from chemically splitting creatine phosphate is phosphorylated using energy from ATP produced aerobically in the mitochondria of the muscle. This process requires an increase in aerobic metabolism (oxidative phosphorylation) and returns creatine phosphate concentrations to normal within a minute or two.
Explain glucose homeostasis and hormones that are involved.
Insulin
Uptake and storage of glucose and FFA
Plasma concentration decreases during exercise
Decreased insulin response following training
Glucagon
Mobilization of glucose and FFA fuels
Plasma concentration increases during exercise
Decreased response following training
Explain two AA supplements that may improve performance and their proposed benefits
Beta-alanine - increase carnosine, buffering capacity
HMB - metabolite of leucine, effectiveness with muscle recovery with HIT exercise
Arginine - stimulate GH release if taken before exercise
BCAAs - cognition and reduction of postexercise fatigue
Explain the metabolism of fats
2. Within an adipocyte, hormone-sensitive lipase will break down a stored triglyceride into glycerol and three fatty acids, which diffuse into the capillary circulation.
3. Then are metabolized through β-oxidation to generate Acetyl CoA to enter into the Krebs cycle and undergo OXPHOS
4. The fatty acids are bound to albumin for transport.
5. This process is initiated with the stimulation of adrenergic receptors on the cell membrane by stress hormones such as epinephrine and norepinephrine.
What are the components of EE and how does it relate to athletic performance?
•Resting metabolic rate
Amount of energy required to maintain nonactive but alert state
~50-70% daily expenditure
•RMR prediction equations
Mifflin St. Jeor
Harris-Benedict
Cunningham equation (requires LBM)
•Thermic effect of food
Digestion and absorption of food
~10-20% of daily expenditure
•Physical Activity
Activities of daily living
Exercise
~20%
•Energy available to perform all other functions after energy cost of exercise is subtracted
What is the purpose of the ETC?
Electrons passed along series of complexes
O2 is final acceptor, picking up electrons in form of Hydrogen to form water
Electrons power ATP production
Explain what it means to "Hit the Wall" and what you can do to prevent this.
2. Why are fats important for CHOs?
Hitting the wall - inability to maintain exercise intensity**
Caused by glycogen depletion because ”fats burn the flames of carbohydrates”
Carbohydrates prime the Krebs cycle with Krebs cycle intermediates (glycolysis). This speeds up the Krebs cycle and improves fat metabolism
Prevention: Glycogen loading / supercompensation
Explain the effects of pre-sleep casein
Pre-sleep casein protein intake (30–40 g) increases overnight MPS and metabolic rate without influencing lipolysis.
Casein-based protein consumed in the morning (10 am) and evening (10:30 pm) was more beneficial for increasing fat-free mass than consuming the protein supplement in the morning (10 am) and afternoon (~3:50 pm)
Explain the fat burning myth
Fat Burning Zone Myth - where a maximal proportion of fat is burned – states we burn more fat calories at low intensity than at high intensity
As exercise intensity increases, there is a decrease in the % of Fat used as a fuel source and an increase in the % of CHO used as a fuel source, but the TOTAL calories EXPENDED GOES UP – WE ACTUALLY HAVE A GREATER NUMBER OF FAT CALORIES EXPENDED DURING HIGH INTENSITY
Explain the sliding filament theory
Use of ATP by muscle
1. Acetylcholine (released by motor neuron) combines with receptors on muscle fiber, causing depolarization and an action potential.
2. Impulse spreads through T tubules, stimulating Ca2+ release from sarcoplasmic reticulum.
3. Ca2+ binds to troponin, causing change in shape. Troponin pushes tropomyosin away, exposing binding sites on actin filaments.
4. ATP is split. Myosin head, now cocked, binds to exposed binding site, forming crossbridge.
5. Pi is released.
6. Crossbridge flexes, and actin filament is pulled toward center of sarcomere. This movement is the power stroke. ADP is released.
7. Actin-myosin complex binds ATP, and myosin detaches from actin.
*Hint, table in Ch 3
Absorptive state -
Glucose used for energy or stored as glycogen
Post absorptive state - Glucose used for energy, some glycogen storage continues; lactate and alanine released to liver to make glucose; fatty acid uptake (provided by the breakdown of fat from adipose tissue) for use as energy
Explain CHO timing for
>60 min
45-60 min
>60 min-2.5 hr
>2.5-3 hr
1-4 g/kg
45- 60 small amounts
>60 min-2.5 hour - 30-70 g (depends on tolerability)
>2.5-3 hr up to 90 g
Explain the types of protein supplementation benefits to increase muscle adaptations from resistance training
How much? How often?
High content in essential AAs.
~20-40 g/ every couple of hours
Whey protein ingested close to resistance exercise, promotes a higher activation (phosphorylation) of mTOR (a key signaling protein found in myocytes that is linked to the synthesis of muscle proteins) – soy is another fast-absorbing protein
- Whey shows an advantage over soy (higher EAA/ Leucine content) – greater activation of MPS
•Decreased muscle and liver glycogen storage and rate of breakdown
•Increased gluconeogenesis
•Increased muscle triacylglycerol storage and utilization
•Increased mitochondrial oxidative capacity
•Increased ketone production
•Decreased use of glycolysis-derived acetyl CoA
Explain the Paleo diet, vegan, omnivore, and gluten-free diet with consequences and benefits
Paleo - meat, fish, shellfish, fruits, veggies, poultry, eggs, roots
•Positively impacts health outcomes, rich in nutrients/ vitamins
•body composition
•glucose tolerance
CON: Can't sustain performance during high volume periods
Vegan -
Pro: inclusion of antioxidants (polyphenols), micronutrients (vitamin C, E), and carbohydrate-rich foods, lower in total and saturated fat and higher in n-6 fats
Con: lower energy intake, may be deficient in some nutrients (e.g., calcium, vitamin D, B12, iron, zinc, iodine), lower n-3 fatty acid levels, could reduce creatine and muscle carnosine stores
Omnivore -
Pro: meets requirements for calcium, vitamin D, B12, iron, zinc, iodine, provides complete protein recommendations
Con: often lacks polyphenols, 58% and 81% more meat and calories than the recommended intake for women and men, excessive iodine, high saturated fat; arachidonic acid, a fatty acid found in meat and linked to lower mood - Depressive symptoms
Gluten -
Pro: weight loss, disease cure/mitigation, readily convert to glucose
Con: low fiber, high fat, low B vitamins, iron, calcium, & zinc, cost, short term, addiction
100 yd dive
200m sprint
800 m sprint
Volleyball
Tennis
200 m sprint - ATP/PCR
800 m - Glycolytic
Volleyball - ATP/PCr
Tennis - glycolytic/ aerobic
and how you can increase speedy refueling
Bergstrom - deplete glycogen stores with hard exhaustion coming up to a race then try to decrease exercise with a high CHO diet
Sherman – HIGH CHO then taper exercise volume down –
Speedy refueling can be accomplished by 1-1.2 g/kg for first 4 hr then resume daily needs
Meat vs plant-based proteins. Is one better than the other? Explain.
1. vegetarian diets often lack equivalent amounts of protein. However, with proper supplementation and careful nutritional choices, it is possible to have complete proteins in a vegetarian diet
2. high-quality, animal-based products (meat, milk, eggs, and cheese) an individual will achieve optimal growth as compared to ingesting only plant proteins. Increased lean mass and decreased fat mass more than the control and soy groups.
3. Soy - may also be responsible for inhibiting growth factors and protein synthesis via its negative regulation of mTOR
Explain the ketogenic diet and its effect on HIIT and endurance training.
>4 weeks adaptations
greatest oxidative adaptations - Long-term adaptation to LCHF diets produces even greater metabolic benefits, including a higher rate of fat oxidation and lower rates of carbohydrate oxidation and glycogenolysis
HIIT?
•Only a few studies have examined the impact of LCHF diets on high-intensity exercise. Several of them failed to account for the changes in body weight and/or body composition and training status
No clear evidence in short term adaptations (~4-5 days) to a high fat diet in athletes to increase performance
•Long-term LCHF diet may enhance performance in ultra-endurance events such as the ultra-marathon and ironman triathlon by supporting a higher fat oxidation rate at higher relative exercise intensity and by having a glycogen sparing effect