Carbohydrate Fatigue: A Case Study
The aim of the experiment is to investigate the effects of carbohydrate receptors in the mouth on exercise performance during a simulated time trial.
Energy is required in the body for metabolic processes, physiological functions, muscular activity, heat production, growth and synthesis of new tissues. Carbohydrates have been researched and studied for centuries and are commonly viewed as a substrate for fuel metabolism, associated with many other energy-demanding processes.
There has been extensive research on the ergogenic effect of carbohydrate ingestion during endurance exercise, (Jeukendrup, 2004) as some studies suggest that the main contributors to fatigue during endurance exercise are dehydration and carbohydrate depletion (Jeukendrup, 2011). …show more content…
Throughout their study, Welsh et al.
(2002) suggest that carbohydrate ingestion before and during exercise is proposed to aid in sustaining optimal functioning of the central nervous system and help enhance perceptual responses.
Duckworth et al. (2013) suggest that CHO ingestion prevents the development of a hypoglycaemic state via the maintenance of blood glucose levels. This, in effect, ensures activation of the reward areas in the brain such as the frontal operculum, orbitofrontal cortex and striatum. Therefore, it is suggested that this lowers the perception of exertion during exercise and possibly reduce the feeling of displeasure and discomfort (Thays de Ataide e Silva et al., 2013). As a result, the onset of fatigue is delayed and exercise performance is in fact enhanced.
The magnitude of performance improvements following CHO ingestion can therefore be explained by the maintenance of blood glucose levels, in addition to increased CHO oxidation rates (Jeukendrup, 2004) and the sparing of muscle glycogen which in turn optimizes glycogen stores and delays muscle glycogen depletion (Coyle et al.,
1986).
A growing number of studies have now shown that rinsing the mouth with a carbohydrate-containing solution is associated with improved high intensity endurance exercise performance.
Carter et al. (2004) provided evidence to support this notion by testing the effects of rinsing a CHO solution in the mouth and then expelling it. Performance improvements were considerably greater when rinsing with the CHO solution compared to the placebo (Jeukendrup et al., 1997).
In a recent study, Pottier et al. (2010) demonstrated that a comparison of both techniques indicated that CHO mouth rinsing may be superior to CHO ingestion where time-trial performance enhancement is being evaluated. A number of exercise studies have suggested that the presence of carbohydrate in the mouth activate oral receptors, which in turn stimulate the reward areas of the brain, ultimately increasing central drive and motivation (Chambers et al., 2009).
Beelen et al. (2009) reproduced the same experimental design as Carter et al; however Beelen et al performed an approximately 1-hr time trial on a cycle ergometer while rinsing their mouths with either CHO solution or water after every 12.5% of the set amount of work. They reported no performance benefits as they found no differences in power output, heart rate, or perceived exertion. Therefore, they came to the conclusion that carbohydrate mouth rinsing does not improve time-trial performance when exercise is performed in a practical, postprandial setting.
Energy is required in the body for metabolic processes, physiological functions, muscular activity, heat production, growth and synthesis of new tissues. Carbohydrates have been researched and studied for centuries and are commonly viewed as a substrate for fuel metabolism, associated with many other energy-demanding processes.
There has been extensive research on the ergogenic effect of carbohydrate ingestion during endurance exercise, (Jeukendrup, 2004) as some studies suggest that the main contributors to fatigue during endurance exercise are dehydration and carbohydrate depletion (Jeukendrup, 2011). …show more content…
Throughout their study, Welsh et al.
(2002) suggest that carbohydrate ingestion before and during exercise is proposed to aid in sustaining optimal functioning of the central nervous system and help enhance perceptual responses.
Duckworth et al. (2013) suggest that CHO ingestion prevents the development of a hypoglycaemic state via the maintenance of blood glucose levels. This, in effect, ensures activation of the reward areas in the brain such as the frontal operculum, orbitofrontal cortex and striatum. Therefore, it is suggested that this lowers the perception of exertion during exercise and possibly reduce the feeling of displeasure and discomfort (Thays de Ataide e Silva et al., 2013). As a result, the onset of fatigue is delayed and exercise performance is in fact enhanced.
The magnitude of performance improvements following CHO ingestion can therefore be explained by the maintenance of blood glucose levels, in addition to increased CHO oxidation rates (Jeukendrup, 2004) and the sparing of muscle glycogen which in turn optimizes glycogen stores and delays muscle glycogen depletion (Coyle et al.,
1986).
A growing number of studies have now shown that rinsing the mouth with a carbohydrate-containing solution is associated with improved high intensity endurance exercise performance.
Carter et al. (2004) provided evidence to support this notion by testing the effects of rinsing a CHO solution in the mouth and then expelling it. Performance improvements were considerably greater when rinsing with the CHO solution compared to the placebo (Jeukendrup et al., 1997).
In a recent study, Pottier et al. (2010) demonstrated that a comparison of both techniques indicated that CHO mouth rinsing may be superior to CHO ingestion where time-trial performance enhancement is being evaluated. A number of exercise studies have suggested that the presence of carbohydrate in the mouth activate oral receptors, which in turn stimulate the reward areas of the brain, ultimately increasing central drive and motivation (Chambers et al., 2009).
Beelen et al. (2009) reproduced the same experimental design as Carter et al; however Beelen et al performed an approximately 1-hr time trial on a cycle ergometer while rinsing their mouths with either CHO solution or water after every 12.5% of the set amount of work. They reported no performance benefits as they found no differences in power output, heart rate, or perceived exertion. Therefore, they came to the conclusion that carbohydrate mouth rinsing does not improve time-trial performance when exercise is performed in a practical, postprandial setting.