NUTRIENT TIMINGSports med 2
How Our Bodies Use Food as Fuel
It takes 24-48 hours to stock/restock the energy your muscles need!
DigestionLiquefied food is sent to the small intestine
where its absorbed into the blood streamMacronutrients: CHO, protein, fatMicronutrients: vitamins, mineralsPhytonutrients: fiber, water
How Our Bodies Use Food as Fuel
The CNS only runs on carbohydrate! Carbohydrate
All CHO is broken down into sugars & absorbed into bloodstream as glucose
Stored in liver and muscle as glycogenHigh intensity exercise= muscles use only glucose to
contractAthletes can consume high CHO diet to manufacture
more glycogen storing enzymes
How Our Bodies Use Food as Fuel
Most whole/real food have a greater amino acid content than any supplement!
ProteinBroken down into amino acids “building blocks”Can’t be stored in large amounts, better to eat small amounts
during each meal, than one large amountBody prefers to use amino acids for growth, repair, and
immune function instead of energyHigh intake can result in excess fluid loss and make you feel
nauseatedAmount needed is determined by weight, and sportBodies can not use more than 2 g/kg of protein per day
How Our Bodies Use Food as Fuel
FatRemains in the stomach longer, complicated to
digest, not immediately ready for fuelCHO is needed to burn fatDietary fat- needed for hormones, affects BP,
inflammation and thickness of bloodBody fat- part of cell membranes, nerve sheaths,
protect and insulateOnly burned for fuel during aerobic metabolismIntramuscular fat burned at moderate intensity
exercise lasting 2 hours.
How Our Bodies Use Food as Fuel Metabolism
Process by which nutrients are broken down and utilized as fuel
When energy is required fuel is metabolized
How Our Muscles Use Food as Fuel Anaerobic
Oxygen is not part of the metabolic processGlucose is the only fuel usedGlycolysis produces ATP as a by-productATP= true energy muscles use to contractCreatine helps recycle ATP for more energy
AerobicGives off more ATP energy, but you have to work at
lower intensitySome protein can contribute but mostly fat and CHO
are used
How Our Bodies Know When to Use Fuel through Hormones
Hormones = messengers produced by glands
Glands= direct changes that need to occur in body.
Changes can be anabolic (muscle building) OR catabolic (break down muscle)
Must have hormone homeostasis to use Fat, CHO & protein efficiently
HORMONES: Anabolic
Testosterone: aids in muscle buildingStimulated by exercise but is variable
depending on type and intensityHigh or low levels of fat content can
negatively affect levels
Nutrient timing + TestosteroneFood (small meal of pro & cho) MAY help
move testosterone from blood into muscle. Not know for sure
HORMONES: Anabolic
Growth Hormone: promotes muscle growth with uptake of
amino acids and glucose + breaks down fat tissue
Stimulated by the hypothalamus.Affecting factors:
○ Stress, sleep, age, genderFactors that help release:
○ Sleep and protein
HORMONES: Anabolic IGF-1 (insulin like growth factor)
Stimulates cell growth and protects against cell death
Stimulated by high diet in protein and CHO and growth hormone
Insulin: Is released by pancreas after eating to bind with
glucose from food intake.Transports energy (glucose) from blood to
musclesStored in muscles as glycogen
HORMONES: Catabolic Glucagon
Released when blood sugar is low and muscles need energy
Produced by pancreas but works opposite of insulin
Glucagon signals liver, the liver releases glycogen (stored energy) into the bloodstream and goes to where it is needed (usually the brain and CNS)
Considered catabolic because if no glycogen stored in liver it has to break down protein or fats to make new glucose.
HORMONES: Catabolic Epinephrine & Norepinephrine
(catecholamines): make sure brain and muscles have fuelMade by the adrenal glandsSignal muscles to use glycogen
for fuel, if that runs out they signal the liver to release glucose
Their job is to release the fuel from the food eaten before activity to keep you going
HORMONES: Catabolic Cortisol (stress hormone)
Produced by adrenal gland under stressful situations (ie: prolonged exercise)
Also used as an anti-inflammatory (activates cells)Breaks down proteins from cells and turn them
into amino acids then send them to liver to produce glucose
Works opposite insulin and decreases protein formation (bad for athletes). It is not part of the building of muscle but the breakdown
Body should use food for fuel but will use Cortisol in emergency
Nutrient Timing Principles for Athletes Aim for consistency Go for Quality Tune in to Timing
Nutrient Timing Principles for Athletes Aim for Consistency…in fueling
Scheduled meals AND snacks…○ don’t starve your body/brain○ Decrease risk of injury○ Keeps energy levels consistent○ Even calories = balanced cholesterol, blood sugar,
insulin and cortisol levels!
Go for Quality Tune in to Timing
Nutrient Timing Principles for Athletes Aim for consistency
Go for QualityTimes around activity are for fueling.
○ Bars, gels, sports drinksMeal times are for nutrition
○ Choose nutrient food: whole grain, fiber, protein, omega-3 fatty acids, fruits veggies
Tune in to Timing
Nutrient Timing Principles for Athletes Aim for consistency Go for Quality
Tune in to TimingIt matters what, when and how much you eat
See following slides
Before Exercise CHO
Taken 15 minutes before exercise spares glycogen depletion
Choose pure CHO foodsHigh glycogen + insulin = reduced cortisol
ProteinBeneficial when taken with CHO before resistance
trainingNeed more research
FatSlowly digested, do not eat close to exercise
During Exercise CHO
Intake has been shown to improve performance in all types of exercise
Reduces risk of injury, and preserves proteinConsume a mixture of sugars in low concentrate form in
small quantities Protein
Intake during resistance training seems promising to reduce muscle tissue breakdown
More research needed Fat
Not beneficial
After Exercise CHO
Restores energy, helps with immunity, decreases muscle breakdown
2 hours post exercise = fastest rate of glycogen storage
Immediate recovery = High GI CHO 1-1.5 g/kg body weight, repeat in 2 hours
Protein.1 to .2 g/kg body weight included in recovery foodLimits muscle tissue breakdown & promotes muscle
building Fat
Eat dietary fat at snacks & meals away from training.