Carbohydrate Intake: 120g versus 90g
by Doug Stewart
There has been a lot of coverage recently across many different endurance sports discussing the amount of carbohydrates consumed per hour by elite athletes. For example, one of the Team Ineos nutritionists commented on Twitter, or is that ‘X’ now, that:
‘Interest in on-bike fueling is high recently. Little fact:
TDF’22 was an inflection point for me. Highest avg CHO intake recorded.
In Giro & TDF ’23, that number went up by +20g/h’
Moreover, there has been a lot of coverage in triathlon and running around the grams of carbohydrates consumed by athletes when racing. 120g per hour is the most frequently cited consumption rate at the elite level.
TMR Athlete Chelsea © Olly Bowman Photography
Whilst, in the past, experts would recommend consuming around 60g of carbs per hour, this number has increased to 90g per hour more recently (Burke et al. 2011; Thomas et al., 2016). It also used to be recommended that athletes consume a 2:1 glucose to fructose ratio (Jeukendrup 2011; Wallis et al., 2005). However, more recently, academic studies have explored different ratios and found that a more equitable split of glucose (or maltodextrin) and fructose would cause fewer stomach issues, while leading to performance enhancement and efficiency of use (O’Brien et al., 2013; O’Brien and Rowlands. 2011; Rowlands et al., 2015). I was a little surprised that this ratio was actually found to be optimal back in the early 2010s, as I think my first experience of a brand using this approach was Maurten, who were newly launched and provided free samples at the inaugural Swedeman Extreme Triathlon in 2018.
As a result of the increased understanding and optimisation of ratios around the hourly intake, along with gut training (Viribay et al., 2020), athletes are now consuming larger volumes of carbohydrates. To explore the impact of 120g per hour versus 90g per hour on carbohydrate oxidation rates, Podlogar et al., (2022) took eleven well trained cyclists (all male, with an average VO2 Max of 62.6) and had them complete a 3-hour cycle at a matched relative intensity endurance effort. The cyclists either received 120g of carbs per hour in a 1:08 maltodextrin:fructose ratio, or 90g per hour in a 2:1 maltodextrin:fructose mix.
Overall, they discovered that the 120g ingestion increased the oxidation rate from exogenous carbohydrate (those eaten) versus 90g per hour. This is maybe not a huge surprise, as the first group were eating 30g more per hour, and in a ratio that is seen to better than the 2:1 ratio of the 90g consumption. However, the endogenous carbohydrate oxidation rates were the same in both groups. This means that ingesting higher levels of carbohydrates did not appear, in the study, to preserve the body’s own stores of carbohydrates.
However, the researchers acknowledge that future studies should explore simulating more variable power outputs, or speeds, to represent more real-world setting. Moreover, with the study being three hours long, the authors suggest that potentially where endogenous carbohydrate levels are low, then higher levels of consumed carbohydrates may yield performance benefits.
This is perhaps why Team Ineos have increased their carbohydrate intake, and maybe future studies will confirm this is an optimal approach.
References:
Burke LM, Hawley JA, Wong SHS, Jeukendrup AE (2011) Carbohydrates for training and competition. J Sports Sci 29(sup1):S17–S27.
Jeukendrup AE (2011) Nutrition for endurance sports: marathon, triathlon, and road cycling. J Sports Sci.
O’Brien WJ, Stannard SR, Clarke JA, Rowlands DS (2013) Fructose-maltodextrin ratio governs exogenous and other cho oxidation and performance. Med Sci Sports Exerc 45(9):1814–1824.
O’Brien WJ, Stannard SR, Clarke JA, Rowlands DS (2013) Fructose-maltodextrin ratio governs exogenous and other cho oxidation and performance. Med Sci Sports Exerc 45(9):1814–1824.
Podlogar, T., Bokal, Š., Cirnski, S., & Wallis, G. A. (2022). Increased exogenous but unaltered endogenous carbohydrate oxidation with combined fructose-maltodextrin ingested at 120 g h− 1 versus 90 g h− 1 at different ratios. European Journal of Applied Physiology, 122(11), 2393-2401.
Rowlands DS, Houltham S, Musa-Veloso K, Brown F, Paulionis L, Bailey D (2015) Fructose–glucose composite carbohydrates and endurance performance: critical review and future perspectives. Sports Med 45(11):1561–1576
Thomas DT, Erdman KA, Burke LM (2016) Nutrition and athletic performance. Med Sci Sports Exerc 48(3):543–568.
Viribay, A., Arribalzaga, S., Mielgo-Ayuso, J., Castañeda-Babarro, A., Seco-Calvo, J., & Urdampilleta, A. (2020). Effects of 120 g/h of carbohydrates intake during a mountain marathon on exercise-induced muscle damage in elite runners. Nutrients, 12(5), 1367.
Wallis GA, Rowlands DS, Shaw C, Jentjens RLPG, Jeukendrup AE (2005) Oxidation of combined ingestion of maltodextrins and fructose during exercise. Med Sci Sports Exerc 37(3):426–432.