9 | Pre- and post-exercise Flashcards
Purpose of pre-exercise nutrition
Supplement a specific limiting factor in the performance of the exercise. Strengthen the weakest link.
Minimum amount of exercise you need per week
50 min/week
What are the “weakest links”? How do we strengthen it?
- Glycogen (carb loading)
- Phosphocreatine (creatine)
- Muscle acidosis (buffers)
What is carb loading?
Super-compensate glycogen levels. Get glycogen stores up to a level where they haven’t been before.
Modern method of carb loading
Day 1. optional depletion exercise Day 2. regular carb intake, taper exercise Day 3. ^ Day 4. ^ Day 5. high carb, taper exercise Day 6. high carb, taper exercise or rest Day 7. ^ Day 8. complete
What’s the point of tapering exercise?
You exercise less, so you burn less carbs than you normally do. Excess carb is stored as glycogen.
What’s the difference between modern and old method of carb loading?
Old method recommended low carb intake instead of just maintaining regular. This was found to be not effective / might harm athlete.
Glycogen differences between untrained individual, trained, and carb-loaded (mmol/kg of wet muscle)
Untrained: 80
Trained: 125
Carb load: 175-200
What’s training low?
Training in carb-deprived state was found to improve performance and glycogen concentration after 10 weeks
Why might training low work?
Your body adapts to glycogen-depleted state, so you can withstand it during event. Body becomes better at using fat as fuel.
Benefits of protein during workout
- Raise body temperature
- Better blood flow
Is carb/protein drink better before or after resistance training? Why?
Before; possibly because the increased blood flow during workout helps circulate nutrients
- no benefit acutely, but may benefit chronically
Protein, fat, carb in the pre-game meal (3-4 h before) for elite athlete
- moderate in protein
- low in fat and fibre
- high in carb (140 - 300 g)
Pre-game (3 - 4 h before) meal for average exerciser
- 5 - 6 meals per day
- divide calories evenly between those meals
- that’s how much calories you should eat pre-game
- 1/2 those calories should come from carbs (~45 g)
Should the average joe exercise before eating?
Sure, he still has enough muscle glycogen, and he won’t harm himself. Since it’s just casual, no need to eat.
Should competitive athletes eat before exercise?
Depends on the nature of the activity
- casual training => no
- competition => yes
Person should be fuelled with carb before exercise if…
Goal is endurance performance
Fuelling with carb may not be necessary if…
- activity is not endurance-based
- goal is conditioning (training low)
How long does it take for muscle cells to turnover?
~3 months
Muscle protein breakdown vs synthesis: at rest vs after exercise
Although there is less net breakdown after exercise, the overall effect is still breakdown. In order to have muscle synthesis, we need to eat AA + resistance train.
When is best time to intake protein in relation to exercise?
- Timing post-exercise did not matter; just do it within 24h window
- Continuously injecting protein not effective; effect on muscle returned to baseline in 2h
When is best dose to intake protein in relation to exercise?
- 20 g
- Intermediate approach with 4 x 20 g dose is most effective (take every 3 h
Effect of carbs on muscle synthesis
carbs does not enhance muscle protein synthesis when ingested protein is sufficient
What is the best method to recover depleted glycogen after exercise?
- Limitation: most studies done in lab on treadmill or cycle
- Early study found feeding immediately after exercise resulted in better muscle glycogen storage (2-3x) vs feeding after 2h
- Later study found that earlier feeding only made a difference at the 2h and 4h measuring window; same result for early and delayed feeding at 8h and 24h
