Chapter 4 (4.5 + 4.6 only on Midterm 2) Flashcards
What is the daily CHO intake recommendation?
recommended intake is based on individual needs (individual differences)
current recommendation for athletes is 3-12 g/kg of body weight daily
athletes must consume enough CHO daily to replenish muscle glycogen used during training
How should athletes ensure that they consume enough CHO?
need to plan their intake
amount and training of CHO dictated by training and conditioning program, and unique demands of the competitive environment before, during and after exercise
Intake of CHO Prior to Training and Competition
goals to avoid hunger, delay fatigue, minimize GI distress, and preventing dehydration
CHO intake up to 1-4 hours prior to endurance exercise is beneficial
1-4 g/kg of CHO
want to enhance liver glycogen and blood glucose levels
Glycemic index and pre-exercise meals
no clear conclusions on whether you should consume foods low on GI or high on GI
athlete preference at this point
for most athletes the GIU of the pre-exercise meal should rarely be of concern
Intake of CHO During Exercise Training and Competition
helps spare muscle glycogen, maintain glucose concentrations, delay fatigue, and reduce the athlete’s perception of fatigue which all improves performance
activities lasting less than about 45 minutes (usually less than 60 minutes) are unlikely to need to consume CHO during
intermittent high intensity athletes may benefit from CHO intake during practices and games (athlete preference)
more than 1-2.5 hours = 30-60 g of CHO/hour
2.5+ hours = up to 90 g of CHO/hour
Intake of CHO After Training and Competition
main goal is to replenish glycogen stores
in order to optimize glycogen replacement must have CHO and insulin
must consume CHO as soon as possible after exercise session/competition is over (within 2 hours)
want to consume simple CHO’s because they are easier to break down
smaller, more frequent meals can also be used to replenish glycogen stores - elevations in blood glucose and insulin can be sustained for a longer period of time
protein should also be consumed to aid in recovery
How much CHO should you consume following training/competition?
highest rates of muscle glycogen synthesis occurs when consume 1.5 g/kg of CHO in the first hour immediately after exercise
endurance and ultra-endurance athletes need to consume more than 60g of CHO/hour by consuming a variety of sugars due to the limited amount of carrier proteins for each sugar molecule (want to fill all of them rather than just some of them)
How should you refuel between demanding exercise sessions?
less than 8 hours of recovery time should consume 1-1.2 g/kg/hour for the first four hours
How can we maximize muscle glycogen stores?
CHO loading - goal is attain maximum glycogen stores prior to an important competition; for athletes doing 90 minutes or more of continuous exercise; bodybuilders do this to promote muscle definition
Sherman’s modified method - depletion phase (5 g/kg/day of CHO), reduce muscle glycogen, hard training); muscles are starved for glycogen and so they super compensate during repletion phase (muscles store more glycogen as more CHO is converted into glycogen; increase glycogen stores up to 20%); repletion phase (10 g/kg/day; maximize muscle glycogen; light training)
How can training and performance be impaired?
both energy and CHO intake must be adequate or performance will be negatively affected (female athletes often low in energy intake)
insufficient total energy intake = some CHO consumed will be used for immediate energy and will be unavailable for storage as muscle or liver glycogen
during exercise low blood glucose can reduce uptake of glucose by the brain and reduce ability to concentrate
muscle glycogen levels at the beginning of exercise may affect both the intensity and duration of that exercise session
What can low CHO intake lead to?
hypoglycemia = loss of concentration, apathy, light-headedness, shakiness, hunger
acute and chronic fatigue if not getting enough CHO for long period of time
CHO and fiber consumption for good health
adults = 45-65% of total energy intake comes from CHO
no evidence that high CHO intake that accompanies a high level of physical activity is unhealthy
Why is it difficult to have a CHO rich diet?
requires planning
Why do athletes fail to consume an enough CHO?
due to lack of knowledge and lack of time, energy, or skill
Fermentable CHO’s
fermentable di-, mono-, and polysaccharides
some sugars can get fermented when reach our gut
short-chain CHO’s that can cause GI upset due to poor absorption
