Sports Nutrition - Proteins

What are proteins made of

amino acids

Essential amino acids

Indispensable: NOT made in body

Nonessential amino acids

Made in liver/other tissues

Conditionally indispensable amino acid

NOT made in body during stress

6 of the dispensable amino acids fall into here

Major protein roles for the body

tissue growth, muscle repair, adaptation, immune function

Structural, enzymatic, transport, and repair roles

What happens to excess protein

too much → not stored, used as energy or fat

When protein is used for energy

during endurance exercise, when glycogen is low

Protein recommendations for athletes in g/kg

Recreational athlete: Inactive person in recreation activity may increase protein intake from 0.8 to 1.0 g/kg/d

Middle-distance runner: may increase protein intake from 1.2 to 1.5 g/kg/d (cuz volume increase)

Active muscle-building athlete: may increase protein intake to 2.0 g/kg/d to support skeletal muscle mass

Why athletes require more protein than sedentary individuals

Athletes build muscle protein through training, which requires more protein

Importance of protein timing

Moderate amount of protein 3 times a day stimulates muscle protein synthesis to a greater degree

General protein intake per meal

Maximum dose 20-30 grams per meal

Define nitrogen balance

Difference between muscle protein synthesis and muscle breakdown

Positive nitrogen balance

growth period, hypertrophy, bigger muscles

Calculate protein needs based on body weight

Step 1: Nitrogen intake

Step 2: Nitrogen Output

Step 3: Nitrogen balance

Negative nitrogen balance

Muscle loss, breaking down protein

Nitrogen output calculation

UUN (aka urinary urea nitrogen) + 4

Nitrogen balance calculation

nitrogen intake - nitrogen output = Nitrogen balance

How many kcals from protein?

4 kcals

Nitrogen Intake Calculation

Grams of protein / 6.25