As power XAV-939 output was higher in the MD + F condition, this correlated with greater cardiovascular exertion despite similar perceived effort. As both test drinks were matched for electrolyte content, the buffering of endogenous acids is unlikely to be a key mechanism explaining greater power output with MD + F. Instead, higher CHOTOT and potential for liver glycogen sparing with MD + F most likely explains the significant increase in performance. It is difficult to compare data from previous research when different types of performance tests have been employed. When shorter distance preloaded time trials have been assessed,

the use of glucose only beverages resulted in a dose response effect, with 60 g.hr-1 leading to a 10.7% increase in mean power over 20 km compared to lower dosages [43]. However, as a limiting factor for longer duration events may be CHOEXO, such results may not extend to longer time trials when single carbohydrate beverages are used. Furthermore, performance times during sustained

endurance events, such as Ironman Triathlon, have been shown to correlate with higher total CHO intakes ranging from 90–120 g.hr-1[10], despite also relating to a higher Sepantronium incidence of gastrointestinal responses. In the current study, gastrointestinal responses did not impede performance, although it was observed that underlying responses were lower with MD + F compared to MD, similar to previous studies [5]. Where longer time trials (>100 km) have been performed (without prior steady state exercise), much findings are mixed [44–46] both for low (0.62 g.min-1[44]) and moderate (1.10 g.min-1) ingestion rates [45]. As a higher ingestion rate was employed in the current

study, along with greater beverage concentration, the high CHOTOT and CHOEXO rates observed with MD + F may explain the improved performance during a 60 km time trial in comparison to these studies. Additionally, if ergogenic effects occur following peak CHOEXO, then overall trials lasting <120 minutes may not be sufficient to observe performance benefits from combined sugar beverages. Conclusions The use of a commercially available MD + F formula resulted in greater increases in total and exogenous carbohydrate oxidation rates during sustained steady state exercise compared to an isoenergetic MD beverage, and P. Additionally, the inclusion of fructose resulted in matched fluid delivery compared with P, and resulted in performance gains in direct comparison to MD. Athletes undertaking sustained exercise greater than 2 hours should consider strategies utilising combined carbohydrate formulas to maximise carbohydrate and fluid delivery, which may support enhanced exercise performance. Acknowledgements The authors wish to acknowledge High5 Ltd. for providing the support and funding to undertake this study. All products used for test beverages were supplied by High 5 Ltd. independently of the investigatory team.