Sports Nutrition - Carbohydrates

3 main types of carbs

sugars, starches, fiber

Monosaccharide (definition and examples)

Simple Sugars. Ex: glucose, fructose, galactose

Simple vs complex carbs

Simple: breaks down easy + easy digestion + fast energy

Complex: longer digestion + lasting energy + blood sugar control

Carbohydrate digestion begins

in the villi, microvilli, and capillary network of small intestine

What enzymes are involved for digestion

Glucose: SGLT1 (active transport)

Fructose: GLUT5 (facilitated diffusion)

Glucose vs fructose digestion differences

Glucose: small intestine → directly enters bloodstream → stored as glycogen in liver/muscle

Fructose: small intestine → convert to glucose/lactate → stay in gut

What happens in small intestine? (generally)

digestion and absorption of nutrients

Final form absorbed into what

the bloodstream

Where is glycogen stored in body

liver + muscles

What happens when glycogen stores are depleted

Hypoglycemia. Shakiness, sweating, confusion, irritability, lose consciousness.

Which macronutrient is required for anaerobic energy

Carbohydrates

Why carbohydrates are critical for high intensity exercise

helps maintain exercise as muscle glycogen declines

Carbs AMDR

~45-65% of total calories

Carb rec for athletes?

3-12g/kg of body weight (wide range)

3-5g (light activity)

6-10g/kg of body weight recommended for active peoples (moderate)

10-12g (intense training)

Recommended carb intake per hour of endurance exercise

6-10kg

Effects of consuming high fructose based carbohydrate concentrations during exercise

Draws water + GI Distress (diarrhea, bloating, cramping)

Benefit of consuming multiple types of carbohydrates (glucose + fructose)

More total carbs absorbed per hour (due separate pathways) → faster muscle energy delivery → reduce GI distress

Define glycemic index

How much a food increases blood sugar

When high vs. low GI foods are useful for athletes

High GI foods for low blood glucose to improve performance

Low GI foods for high blood glucose

High Glycemic meals for post exercise.

Calculate carbohydrate needs for an athlete using g/kg

4 cals multipled by kg of body weight

Know kcals/g offered from carbohydrates

4 kcals per gram