Nutritional Considerations for Intense Training and Sports Competition

Nutritional Considerations for Intense Training and

Sports CompetitionChapter 8 Part 2

Competition less than 30 min◦ 5,000 meter (~ 12 min)◦ 10,000 meter (~ 26 min)

Not necessary

Carbohydrates During Exercise

Prevention of hypoglycemia◦ Central nervous system effects

Dizziness Nausea Disorientation


High intensity aerobic exercise◦ 1 hour

Decreases liver glycogen 55%

◦ 2 hours Depletes liver and muscle glycogen

Intermittent sports◦ Up to 5 hours


Allows for a greater intensity during prolonged activities About 60 g of carbohydrates each hour benefits:

High-intensity, long-duration aerobic exercise◦ Not needed for repetitive short bouts of near-

maximal effort However, it won’t hurt if you like to drink CHO drinks

during such exercise


Why? Spares muscle glycogen Helps maintain blood glucose levels

Improves mental and physical performance◦ Should only be glucose

Fructose causes significant GI distress


CHO ingestion - Williams (1989)◦ Run a fixed distance in 2 hours

1 liter glucose polymer No difference in total distance covered Running speed greater over last 30 min


Ergogenic Advantage

Ingested CHO available for oxidation◦ How much CHO should be consumed?

Rate of oxidation of exogenous CHO = 1 g/min 30-60 g/h (Coyle, 1991)

◦ When should CHO be consumed? Early and often

Every 15 minutes from the beginning of exercise You may not need it early on, but you do need the fluid

and it’s not gonna hurt you


Fluid replacement ◦ Electrolyte concentrations

Sodium Potassium Calcium Magnesium Chloride


The ideal hydration solution contains between 5% and 8% carbohydrates. Too high, slow gastric emptying, causes diarrhea

Maintains blood glucose during prolonged exercise Allows CHO metabolism to continue at a time

when hypoglycemia would normally occur

Carbohydrate-Electrolyte Beverages

Fluid choices for endurance events◦ Water

No CHO◦ Sports drinks (5-8% CHO + electrolytes)

600-1000 mL Ideal

◦ Soft drink (11% CHO) 500 mL Too much sugar, not enough fluid and too much carbonation

◦ Fruit juices (8-12% CHO) 500 mL Too much sugar, not enough fluid

◦ Sports gel (60-70% CHO) (1-2 gels)


Non-endurance sports (< 30 min)◦ Start well hydrated◦ Replace fluid as soon as possible after

competition◦ Fluids ingested during event won’t help

performance


Events of 30-60 min◦ Begin well hydrated◦ Use fluid replacement plan from training◦ Cool beverage (15-20oC) with or without CHO◦ Fluids likely won’t help, but they may be of

psychological benefit


Events of 1-3 h◦ Begin well hydrated◦ Use fluid replacement use in training

Drink as much as is practical◦ Cool beverage (15-20oC) with CHO◦ Begin ingesting fluid early◦ Plan to consume 30-60 g CHO/h of exercise

Again, every 15 min, 250 ml of fluid


Events greater than 3 h◦ Begin exercise well hydrated◦ Use fluid replacement plan from training◦ Cool beverage (15-20oC) with CHO

Change flavors◦ Start ingesting early during exercise◦ Plan to consume 30-60 g/h ◦ Plan for sodium replacement (most drinks have

sodium in them◦ Plan for solid food as time goes on


Foods (50 g CHO)◦ Bananas (2-3)◦ Jelly beans (50 g)◦ Jam sandwich (2 slices bread, 4 t jam)◦ Chocolate bar (1-2)◦ Breakfast bar (1-2)◦ Sports bars (1-2)


Multiple daily events Team sport tournaments Goals

◦ Restore muscle and liver glycogen◦ Replacement of fluid/electrolytes lost in sweat◦ Regeneration and repair damage caused by

exercise

Recovery

Should include simple and complex carbohydrates Simple: Fruits, juices, lemonade, etc. Complex: Rice, potatoes, pasta, etc.

Single large meal or small frequent meals will replenish glycogen stores.

Should be consumed as soon as possible after the activity

50-75 g CHO ◦ Every 15 min◦ Every 2 h (500-700 g)

Carbohydrates after Exercise

Factors affecting Absorption/Emptying

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Nutritional Considerations for Intense Training and Sports Competition