Carbohydrate ingestion during exercise: time to rethink its role?

The effect of carbohydrate (CHO) ingestion on performance during prolonged exercise has been investigated in a number of studies. The majority of published papers show a positive effect. Does this fact mean that CHO ingestion during exercise is beneficial to exercise performance under all conditions? Is this effect due to biological advantage?

Nassif and colleagues from the School of Human Movement Studies, Charles Sturt University, Australia, published a nice study in 2008 that questions the value of CHO ingestion during exercise.
What they did?
Nine well trained athletes with VO2max 65.8 ml/kg/min cycled at 70% of VO2max until volitional fatigue under three experimental conditions while
  • ingesting placebo capsules with distillated water (PLAc),
  • ingesting CHO capsules with distillated water (CHOc),
  • ingesting CHO capsules with distillated water whilst both researchers and athletes knew that CHO were being consumed (CHOk).
What they found?
  • Exercise duration was similar between PLAc and CHOc
  • Exercise duration was 24% longer in CHOk compared with PLAc
Take-home message
  • The ingestion of carbohydrate capsules did not improve performance under these experimental conditions.
  • Knowledge of the ingested ergogenic substance may improve performance. “Coaches and trainers of endurance athletes should be aware that knowledge of the performance enhancement supplement may have a significant psychological effect on endurance performance” (Nassif et al., 2008). 
Source
Nassif et al. Double blind carbohydrate ingestion does not improve exercise duration in warm humid conditions. Journal of Science and Medicine in Sport 2008; 11: 72-79.
Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s