Study Shows Carbohydrates Loading Increases Performance in CrossFit Athletes by 10%

A recent university study on CrossFit athletes found that carbohydrate loading over three days prior to a testing session (key workout) increased performance by 10.2% compared 4.2% for a control group that maintained their low-carb diet into the testing session.

The study investigated the effect of three consecutive days of increased carbohydrate intake on CrossFit performance.  Eighteen athletes with a history of low carbohydrate intake (<6 g/kg/day) were randomly assigned into either a test group (6-8 g/kg/day) or control group (<6 g/kg/day) and underwent a 9-day training protocol. During days 1, 5, and 9, performance was measured as repetitions completed during a 12 minute CrossFit workout. Oxygen consumption (VO2), respiratory exchange ratio (RER), and blood lactate (BL) were also measured.

On days 6–8, the test group did a carbohydrate load, increasing from <6 g/kg/day to 6–8 g/kg/day; the control group maintained their current intake. On days 6 and 7 both groups performed CrossFit workouts followed by a day of rest prior to day 9; their final test day. On day 9 the test group displayed a 10.9% repetition increase compared to a 4.2% by the control group. VO2, RER, and BL were not influenced by the experimental intervention.

The researchers suggest that the CrossFit-embraced practice of moderately-low carbohydrate diets (paleo, zone) may be adequate in carbohydrates during short periods of training, however, they suggest that extended training periods may be affected and further testing is warranted.

While this isn’t a long term study on endurance athletics nor does it look at the timing of carbohydrates within the training day it does show the impact that having a higher carbohydrate diet or carb loading can do for key sessions.  Another thing to note is that the duration of the test sessions were only 12 minutes, but were high intensity CrossFit workouts.  Imagine the impact to endurance athletes were a high intensity threshold improvement or speed improvement workout can equate to 60-90 minutes of active time at the track or on the bike.

Currently in sport there are virtually no training protocols were the athlete trains for such short periods within a training cycle that they wouldn’t see an advantage of replenishing their carbohydrate stores.  The recommendation that the low-carbohydrate diet could work to do this in the short term, would require more time “off” than “under load” for this to occur.  This would lead to underperformance in workouts or even maladaptation.

The simple truth is carbohydrates are king for athletes, but must be used appropriately within the training cycles and to proportions that match the athlete’s goals.  No simple equation of grams per kilogram of body mass will get the athlete to peak performance, but a lack of carbohydrates will show through in stunted growth, performance, and overall wellness.  The question is how far does the athlete want to go!

To learn more about nutrition for performance join Triple Victor and learn how to meet your nutritional needs, how to manage weekly and daily meal planning, and how to fuel for workouts, recovery, and racing.