Respiratory Quotient

• Useful to deduce substrate in person’s metabolism at specific time; oxygen volume in and carbon dioxide volume out are measured, from this respiratory quotient (RQ) calculated; CO_2 volume produced/O_2 volume consumed
• RQ values of following substrates are well documented from previous investigation: carbohydrate 1.0, protein 0.8-0.9, and fat 0.7, RQ value of most animals at rest is in range of 0.8 to 0.9 (human: ~0.85)
• Necessary to view data with caution, a mixture of substrates may be used; RQ of 0.8 could point to both protein and fat being used, RQ is >1, indicates anaerobic respiration occuring more CO_2 is produced than O_2 consumed