We’re looking into a study here, published in the Medicine & Science in Sports & Exercise journal, which ventures into the intersection of high-intensity exercise and rapid carbohydrate loading. The question being asked is – “Does a combination of short, high-intensity workouts followed by a day of high-carbohydrate diet work as an effective carbohydrate loading protocol?”.
In this study, we have 7 endurance athletes performing 150-second exercises at an intensity level of 130% of their peak oxygen uptake (VO2peak). This was followed by a 30-second all-out effort. In the following 24 hours, each athlete was asked to consume carbohydrates at a rate of 12g per kg of lean body mass, equivalent to 10.3g per kg of actual body mass. What they ate was high-glycemic, carbohydrate-dense foods.
The findings? Muscle glycogen saw a significant increase, from a baseline level of 109.1 to 198.2 mmol/kg in just 24 hours. These levels matched or even exceeded those reported in previous studies that utilized a 2-6 day loading protocol. Upon muscle biopsy analysis, it wasn’t just the overall glycogen stores that saw an increase. The glycogen reserves in the Type I, IIa, and IIb muscle fibers all reached comparable levels after a day of high carbohydrate intake.
What’s the takeaway from this study? It suggests that coupling short, high-intensity workouts with subsequent high carbohydrate consumption allows athletes to achieve supra-normal muscle glycogen levels in just 24 hours.
Practical Implication? Here’s where we land – traditionally, we’ve heard of carbohydrate loading protocols spanning 2 to 6 days. This research suggests that a single day of loading could be sufficient, which is not only easier but also fits well into the pre-race plan. Note that the amount of carbohydrates consumed is quite large, and athletes might need to measure their food (at least initially when following this protocol) to ensure they’re getting enough. A sensible recommendation would be to consume 10-12g/kg of carbs spread over three to four meals the day before the race.