Legal Nutritional Boosting for Cycling

The effect of carbohydrates with different levels of digestibility on energy metabolism in vivo under hypobaric hypoxic conditions

Current strategies for improving energy supply in hypobaric hypoxic environments are limited. Therefore, this study investigates the effects of four carbohydrates with different levels of digestibility on energy metabolism in vivo in hypobaric hypoxic environments. First, we characterized the four types of carbohydrates. Subsequently, reverse transcription quantitative polymerase chain reaction (RT-qPCR) was used to characterize the expression of GLUT1, GLUT2, and SGLT1 in the glucose transport pathway in vivo. In addition, the effects of different levels of carbohydrate digestibility on energy expenditure were evaluated in vivo. The results showed that pre-gelatinized corn starch significantly increased GLUT1 gene expression in the hypobaric hypoxic conditions (1.58 times, compared to normobaric normoxic). In addition, pre-gelatinized corn starch increased energy expenditure in the hypobaric hypoxic conditions and performed better in terms of glycogen accumulation and glucose transport. Therefore, pre-gelatinized corn starch administration may be a promising strategy for long-term energy supplementation in hypobaric hypoxic.

Nutrition in Cycling

Cycling is predominantly an endurance sport in which fuel utilization for energy production relies on the availability and delivery of oxygen to exercising muscle. Nutrition and training interventions to improve endurance performance are continually evolving, but ultimately, prescription should aim to generate improvements in cycling power and velocity while prioritizing athlete health and well-being. The wide range of cycling events and the different environments in which events take place pose a variety of nutrition-related challenges for cyclists. This review addresses some of these challenges and highlights recent advancements in nutrition for cycling performance.

Doing supplements to improve performance in club cycling: a life-course analysis

Using qualitative life-course and pathway analysis, this article explores the beliefs that serious club cyclists have about performance improvement, and what they think are appropriate and inappropriate ways of achieving it. We interviewed 11 cyclists from suburban clubs in Melbourne, Australia, and invited them to discuss their approach to training, racing, and supplementation. We found that each of the 11 cyclists were not only committed to the sport, but also paid a keen interest in bike technology and training regimes. In addition, they believed that supplement use was integral to meeting the physical and mental demands of their sport, even at club level. They also understood that supplement use, like training regimes, followed a sequential pathway where the accumulation of capacity, know-know, and knowledge, allowed progression to the next level of performance. And, like similar studies of club cycling in Europe, this cohort of cyclists balked at using banned substances, but also believed that in order to effectively transition to the elite - that is, professional - level, some additional supplement and drug-use was essential.

Changes in hydration status of elite Olympic class sailors in different climates and the effects of different fluid replacement beverages

Background

Olympic class sailing poses physiological challenges similar to other endurance sports such as cycling or running, with sport specific challenges of limited access to nutrition and hydration during competition. As changes in hydration status can impair sports performance, examining fluid consumption patterns and fluid/electrolyte requirements of Olympic class sailors is necessary to develop specific recommendations for these elite athletes. The purpose of this study was to examine if Olympic class sailors could maintain hydration status with self-regulated fluid consumption in cold conditions and the effect of fixed fluid intake on hydration status in warm conditions.

Methods

In our cold condition study (CCS), 11 elite Olympic class sailors were provided ad libitum access to three different drinks. Crystal Light (control, C); Gatorade (experimental control, G); and customized sailing-specific Infinit (experimental, IN) (1.0:0.22 CHO:PRO), were provided on three separate training days in cold 7.1°C [4.2 – 11.3]. Our warm condition study (WCS) examined the effect of fixed fluid intake (11.5 mL^.kg^.-1.h^-1) of C, G and heat-specific experimental Infinit (INW)(1.0:0.074 CHO:PRO) on the hydration status of eight elite Olympic Laser class sailors in 19.5°C [17.0 - 23.3]. Both studies used a completely random design.

Results

In CCS, participants consumed 802 ± 91, 924 ± 137 and 707 ± 152 mL of fluid in each group respectively. This did not change urine specific gravity, but did lead to a main effect for time for body mass (p < 0.001), blood sodium, potassium and chloride with all groups lower post-training (p < 0.05). In WCS, fixed fluid intake increased participant’s body mass post-training in all groups (p < 0.01) and decreased urine specific gravity post-training (p < 0.01). There was a main effect for time for blood sodium, potassium and chloride concentration, with lower values observed post-training (p < 0.05). C blood sodium concentrations were lower than the INW group post-training (p = 0.031) with a trend towards significance in the G group (p = 0.069).

Conclusion

Ad libitum fluid consumption in cold conditions was insufficient in preventing a decrease in body mass and blood electrolyte concentration post-training. However, when a fixed volume of 11.5 mL^.kg^.-1.h^-1 was consumed during warm condition training, hydration status was maintained by preventing changes in body mass and urine specific gravity.

Carbohydrate and exercise performance: the role of multiple transportable carbohydrates

PURPOSE OF REVIEW

Carbohydrate feeding has been shown to be ergogenic, but recently substantial advances have been made in optimizing the guidelines for carbohydrate intake during prolonged exercise.

RECENT FINDINGS

It was found that limitations to carbohydrate oxidation were in the absorptive process most likely because of a saturation of carbohydrate transporters. By using a combination of carbohydrates that use different intestinal transporters for absorption it was shown that carbohydrate delivery and oxidation could be increased. Studies demonstrated increases in exogenous carbohydrate oxidation rates of up to 65% of glucose: fructose compared with glucose only. Exogenous carbohydrate oxidation rates reach values of 1.75 g/min whereas previously it was thought that 1 g/min was the absolute maximum. The increased carbohydrate oxidation with multiple transportable carbohydrates was accompanied by increased fluid delivery and improved oxidation efficiency, and thus the likelihood of gastrointestinal distress may be diminished. Studies also demonstrated reduced fatigue and improved exercise performance with multiple transportable carbohydrates compared with a single carbohydrate.

SUMMARY

Multiple transportable carbohydrates, ingested at high rates, can be beneficial during endurance sports in which the duration of exercise is 3 h or more.