10.21.13 kin 110 class notes- PRO as an energy source- Protein most misunderstood concept in sport nutritiono Athletes overemphasize the importance of proteino Oro Underemphasize it and think its less important than it really is- Protein marketed as both food and diet- Popularity of PRO supplementso 1. Main component of muscle - trueo 2. Important for energy – production – true but mostly not trueo 3. People don’t eat “enough” – not true!o 4. Needs for athletes much higher than for non-athletse does it matter how much other energy? Does it matter what types of exercise you are doing?- Differences between PRO in food and as supplements:o Supplements purified so other components are removedo CHO, fat, vitamins, mineralso Protein supplements are not the same…?- All PRO is functional (structural, enzymes, transporters, immune system)o PRO deficiencies more serious- Major PRO sourceso Animal productso Some plant products Tofu- Energy value for PROo Total energy= 5.25 kcal/gramo But: 1. PRO only 92-94% digestible (especially plants pros ) Lose .40 kcal/gram so digestible energy = 4.85 kcal/gram- 2. Energy in the nitrogen group cannot be broken down by human enzymes (metabolized)o .85 kcal/g = nitrogeno 4.0 kcal/g for PRO- correcting for digestibility and metabolism, 4.0 kcal/g in PRO- essential amino acids have to be part of diet about 9/20 amino acidso non essential amino acids = can be synthesized from other amino acids- PRO from other animal sources= complete amino acid ratio similar to human needso Plant PRO = “incomplete” 1 essentialo Ratio low compared to human needs Beans low in methionine Corn, rice low in lysine- Problem of incomplete PRO for vegans, vegetarians Incomplete proteins = complete proteins Tofu & rice…- Need to understand use of PRO for energy during exercise and how important is ito Which athletes need more protein and why?- How much PRO is used during exercise?- Is it affected by intensity or duration?- How to dietary PRO needs change with total energy needs?- 1800 leibig PRO supplies all energy for exerciseo 1840’s: smith measures N2 and CO2 excretion of prisoners- 2 german researchers challenge idea that PRO alone powers
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