Module 3.2 Flashcards
Why is protein important?
Protein is an essential nutrient in the diet, being used to manufacture body proteins that have important structural and functional roles in the human body.
Structural proteins
needed to build connective tissue, cell membranes and muscle cells
Regulatory proteins
act as enzymes or transport vehicles
Proteins are made up of
various sequences of about 20 different amino acids. Nine of these amino acids are essential and must come from the diet or from the breakdown of other proteins in the body.
minor fuel source during excersize
Some amino acids are used as a minor fuel source during exercise.
Do athletes require more protein?
- Endurance athletes in heavy training require extra protein to cover a small proportion of the energy costs of their training and to assist in the repair and recovery process after exercise.
- Strength athletes, who are interested in gaining muscle size and function, require more protein in the early stages of very intensive resistance exercise
adolescents protein requirments
Athletes who are growing, such as adolescents, have additional protein requirements.
grams of protein per kg of body mass required for sedentary individual
0.8
g of protein/ kg required for general training program
1.0
g/protein per kg of endurance althlete
1.2-1.6
g of protein/kg required for endurance athelte extreme training program
2.0
strength althete undertaking heavy training program g of protein/kg
1.2-1.7
adolescent athletes g of protein/kg
2
Do athletes need to eat more protein-rich foods?
athletes provide protein intakes that are well in excess of 1.2-2.0 g/kg body mass per day - especially in the case of strength-training athletes. Therefore, there is no justification for special high protein eating strategies for sport.
It seems that some athletes swear by high-carbohydrate diets,
while others have moved to high-protein diets? Who is right?
there is no need to take one extreme view or the other. Many athletes do not realise that it is possible, and beneficial, to consume a diet that achieves the muscle’s carbohydrate fuel needs, as well as providing a protein intake that easily meets the increased protein needs for sport.
a combination of carbohydrate and protein is the best way to meet sports nutrition goals
How does timing and teamwork of protein and carbohydrate
work?
Muscle and body protein metabolism is a constant balance between protein breakdown and protein rebuilding. During exercise the balance shifts towards protein breakdown, while during recovery the balance tips in the opposite direction.
consuming protein immidetately after excersize does what
appears to enhance muscle uptake and retention of amino acids, and promote a more positive protein balance.
It is still not clear whether these benefits are apparent when the 24 hour picture
Snacks or light meals that achieve this team-work include
Flavoured yoghurt
* Flavoured milk drinks
* Fruit smoothies
* Liquid meal supplements (e.g. Sustagen Sport)
* Sandwiches with meat, cheese, chicken or peanut butter fillings
* Breakfast cereal and milk
* Sports bars
Can athletes have too much protein?
High protein intakes can increase the amount of calcium excreted in the urine. This may cause problems with athletes at risk of weakened bones
High protein intakes based on the consumption of large amounts of animal foods (e.g. meat and dairy foods) can result in a greater fat intake.
High protein intakes may increase fluid requirements
excessive focus on high protein foods may displace other valuable foods (e.g. fruit and vegetables) or other important nutrients such as carbohydrate and fibre from the diet.
Can athletes have too little protein?
Failure to consume sufficient protein on a regular basis may cause muscle to be broken down to ensure a continual supply of essential amino acids in the body
what types of athletes consume not enough protein
- Athletes on low energy diets trying to achieve or maintain a lower body mass/body fat level, especially those undertaking extreme restriction to lose weight rapidly
- Athletes restricting dietary variety, fussy eats, alergies, etc
Are protein supplements useful?
They tend to provide very large amounts of protein and little other nutrients. There is no need for the amount of protein provided by many supplements and there is certainly no justification for the extra cost.
most suitable protein supplement
provides both protein and carbohydrate.
Good alternatives to protein supplements include
include homemade fruit smoothies, liquid meal supplements such as PowerBar Protein Plus powder and 20 g skim milk powder added to regular milk.
key to weightloss
consume less kilojoules than you use over a period of time.
high protein, low-carbohydrate diets result in
loss of water and glycogen. This might result in a decrease on the scales but does nothing to reduce body fat. In the long-term, high- protein, low-carbohydrate diets may result in fat loss.
- In the long- term, these diets will see muscle mass decrease.
is high protein low carb maintainable
It is almost impossible to maintain a high-protein, low-carbohydrate diet for the long term because they are boring and unappetising. The lack of carbohydrate reduces energy levels, impairs performance and causes nausea and lethargy.
- restrict the intake of many essential nutrients in the diet.
A well-designed diet for an athlete is
combination of proper energy intake, proper timing, along with proper training.
An energy deficient diet during training may lead to
loss of muscle mass and strength, increased suscepti- bility to illness, and increased prevalence of overreaching and/or overtraining
The current recommended level of protein intake
(0.8 g/kg/day) is estimated to be sufficient to meet the needs of nearly all (97.5%) healthy men and women age 19 years and older
If an athlete does not ingest sufficient amounts of protein, he or she will maintain a
negative nitrogen balance, which can in- crease protein catabolism and slow recovery
Nitrogen balance is quantified by
calculating the total amount of dietary protein that enters the body and the total amount of the nitrogen that is excreted
Proteins differ based on
the source, the amino acid profile and the methods of isolating the protein
Great dietary sources of low-fat, high-quality protein are
skinless chicken, fish, egg whites and skim milk while the highest quality supplemental sources are whey, colos- trum, casein, milk proteins and egg protein
Two of the most widely used protein supplements are
casein and whey, which can both be found in milk prod- ucts.
Research has demonstrated that whey
“whey protein elic- its a sharp, rapid increase of plasma amino acids follow- ing ingestion, while the consumption of casein induces a moderate, prolonged increase in plasma amino acids that was sustained over a 7-hour postprandial time period,”
benefits of leucine
leucine plays the most significant role in stimulating protein synthesis (5). Therefore, supplementa- tion of branched-chain amino acids may be beneficial to athletes.
The addition of leucine resulted in
a lower protein oxidation rate compared with the carbohydrate/protein trial.
The study concluded that co-ingestion of protein and leucine stimulates muscle protein synthesis and optimizes whole body protein balance
During prolonged aerobic exercise
the amount of free trypto- phan increases and therefore the amount of tryptophan entering the brain increases, resulting in fatigue
when BCAAs are present in the plasma, in significant amounts, they may decrease the amount of trypto- phan reaching the brain, therefore decreasing feelings of fatigue
It has been suggested that the recommended daily allowance (RDA) for leucine alone should be
45 mg/kg/day for sedentary individuals, and even higher for active individuals
major organizations recommend athletes consume more than the RDA for protein, approximately
1.4 – 2.0 g/kg of body weight
General activity calorie/protein intake
25 – 35 kcals/kg/day
0.8 – 1.0 g/kg/day
Strength training athletes calorie/protein intake
50-80 kcals/kg/day
1.4 - 1.8 + g/kg/day
endurance athletes calories/protein intake
150 – 200 kcals/kg/day
1.2 –1.4 g/kg/day
