Lecture 2: Bioenergetics and Carbohydrates Flashcards
Define: bioenergetics
the study of how energy is captured, transferred and/or used within a biological system
Define: fitness
the ability to carry out daily tasks with vigour and alertness, without undue fatigue, and with ample energy to enjoy leisure time pursuits and to meet unforeseen emergencies
How your body can respond in emergency situations depend on…
muscle glycogen levels
Define: fatigue
a physical condition marked by the point in time at which the work output or performance cannot be maintained
Define: ATP
the high energy molecule that is the direct source of energy for all biological processes
Poor nutrition can directly affect _____, which results in _____
ATP production;
decrease in sport performance
Sources of ATP
1) Carbohydrate
2) Fat
3) Protein
Energy systems
1) Phosphagen system (ATP-PC)
2) Anaerobic system (glycolytic)
3) Aerobic system (oxidative)
Rate & capacity of ATP-PC system
Rate: very fast
Capacity: very limited
How long does the ATP-PC system last?
5-15 sec
Rate & capacity of anaerobic system
Rate: fast
Capacity: limited
How long does anaerobic system last?
1-3 min
Rate & capacity of aerobic system
Rate: very slow
Capacity: unlimited
At what distance does a sprinter and long-distance runner tie?
600m
For 800m race, what energy system is being used?
Begins with ATP-PC, but runs out.
50:50 anaerobic to aerobic after.
What determines which energy system is used?
1) Intensity of effort
2) Duration
3) Fitness status
4) Nutritional status
At ___% of VO2 max, the % energy from fat and carbs are the same.
33
How long does aerobic system last?
hours
Differences between trained and untrained individuals during exercise
- Trained produces more work per mL O2
- Trained burns more fat before burning CHO
Why are trained people better at using fat as fuel vs untrained people?
- More mitochondria
- More efficient at distributing and using oxygen
- Enzymatic differences
What’s so good about CHO?
- Only nutrient that provides energy for anaerobic activities
- Spares muscle tissue from being broken down
- Fuel used by the brain
What is “bonking”?
Brain “shuts down” when all the glucose is used up. Happens around 20 mile mark in a marathon.
Types of CHO
1) Glucose
2) Complex carbs (starch, glycogen)
3) Fibre
Define: startch
the storage form of CHO in plants
Define: glycogen
the storage form of CHO in animals
Define: fibre
non-digestible plant based CHO
How many CHO should an endurance athlete eat?
6-10g per kg per day
How many CHO should a strength athlete eat?
4-7g per kg per day
What is periodization?
Athletes change their training during the course of the year, so they should also adjust their nutritional intake in response. CHO intake varies greatly depending on type of training, but protein stays about the same.
3 pillars of CHO availability
1) Maximize glycogen (in advance)
2) Pre-game meal
3) CHO during event
Carb storage
1) < 500g muscle glycogen
2) <100g liver glycogen
3) Few grams blood glucose
____ is the main CHO fuel for high intensity exercise
Glycogen
For intermittent high-intensity sports, the amount of glycogen used to do successive intervals…
will become less even if the same amount of work is done (brain learns the motion)
Fast twitch muscle
Used during anaerobic exercise (fatigue quickly)
Slow twitch muscle
Used during aerobic exercise (last for long time)
Define: Glycemic Index (GI)
an index for classifying carbohydrate food based on how quickly they are digested and absorbed into the bloodstream when consumed in isolation.
When is GI useful in sports?
Controversial. Perhaps if energy is needed immediately, high GI foods should be consumed.
High GI =
Low GI =
High GI = absorbed quickly
Low GI = absorbed slowly
Net ATP from anaerobic metabolism
2/3 ATP
Net ATP from aerobic metabolism
32/33 ATP
Where does aerobic metabolism occur?
mitochondria
Factors affecting how many carbs athlete should eat?
- Periodization
- Carb availability
