Protein

Question 1

Some positives of consuming protein for athletes

Answer 1

Protein can enhance CHO storage if below optimal 1.2g/h intakes

Can also improve post exercise rehydration

Question 2

In the study by Josse et al. (2010) covered in the protein lecture, 2 groups of women underwent 12 weeks of progressive resistance exercise (5 sessions a week). One group received 1 L of skimmed milk and the other group 1 L of a carbohydrate solution in the hour post-exercise, with the skimmed milk gaining more lean body mass and losing more fat mass than the carbohydrate group. The skimmed milk group gained 1.9 kg of lean mass and lost 1.6 kg of fat mass. From these values of lean and fat mass, estimate the average energy balance that subjects experienced over the 12 weeks? Also estimate this as daily energy balance? You can assume energy values of 38 kJ/g of fat and 17 kJ/g protein.

Answer 2

Energy lost as fat over the 12 weeks = 1600 g x 38 = 60800 kJ
Grams of protein gained over the 12 weeks = 1900 g / 5 = 380 g
Energy gained as protein over the 12 weeks = 380 g x 17 = 6460 kJ
Energy balance = 6460 kJ – 60800 kJ = -54340 kJ in 12 weeks
= -54340 kJ / 84 = -647 kJ per day

Question 3

Is protein enhanced by carb intake ?

Answer 3

No

Question 4

What percentage of muscle is protein ?

Answer 4

20%

so for every kilo of muscle there is 200g of protein.

Question 5

An 80 kg novice male body builder wants to gain 15 kg of muscle within 1 year (the absolute maximum he could expect to put on). You have advised him that a more reasonable goal would be 5 kg of muscle within the year – he isn’t convinced. Estimate (calculate) how much additional protein would be needed per day in order to reach each of these targets assuming that his current level of protein intake (1.4 g/kg/day or 112 g/day) is achieving nitrogen balance.

Answer 5

1a) 15 kg muscle contains 3 kg of protein (80% water content)
3 kg protein per year = 3000 g / 365 days = 8.2 g per day
Protein intake increased from 112 g/day to 120 g/day (from 1.4 g/kg/d to 1.5 g/kg/d)

1b) 5 kg muscle contains 1 kg of protein (80% water content)
1 kg protein per year = 1000 g / 365 days = 2.7 g per day
Protein intake increased from 112 g/day to 115 g/day (from 1.4 g/kg/d to 1.44 g/kg/d)

Question 6

Is protein intake post exercise important ?

Answer 6

No for protein immediate differences in response but can be considered beneficial for protein intake timings.

Question 7

Why is exercise induced increase is protein turnover rate useful for adaptation?

Answer 7

A high turnover rate allows faster breakdown and rebuilding of cellular/ muscular components that may not be as optimal for the type of demand they are being placed under.

Question 8

A 60 kg female endurance athlete is advised that she should be achieving a daily protein intake of 1.2 g/kg/day. Analysis of her food intake records indicates that her total daily energy intake is 12 MJ and that her protein intake provides 12% of this energy. Calculate her actual intake of protein in g/kg/day. Does she need to supplement her diet with extra protein? You can assume that the energy available from dietary protein is 17 kJ/g.

Answer 8

Energy from protein = 12% of 12 MJ = 12/100 x 12 = 1.44 MJ or 1440 kJ
Energy value of protein is 17 kJ so 1440 kJ = 1440/17 = 84.7 g of protein
For this 60 kg athlete relative protein intake = 84.7/60 = 1.4 g/kg/day
Additional protein is not necessary for this athlete

Question 9

What are the 8 essential amino acids ?

Answer 9

Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine