Endurance Training Effects of Hi-Carb vs. Low-Carb Intake
/Carbohydrate (CHO) intake and the effects it has on a body undergoing regular endurance training is a critical topic for runners and coaches to have an accurate working understanding about.
There are distinct benefits to working out in a CHO-rich environment as well as drawbacks — and the same goes for a CHO-depleted environment.
My simple heuristic is this:
When the training objective is to increase POWER (speed, pace, force) a CHO-rich environment is best.
When the training objective is to increase CAPACITY (duration, efficiency) a CHO-depleted environment is desired.
This 36-page study, Regulation of Muscle Glycogen Metabolism during Exercise: Implications for Endurance Performance and Training Adaptations, offers evidence about the different effects various CHO training situations have on endurance performance and training adaptations.
Here’s an expert from the study:
When the goals of the training session are to complete the highest workload possible over more prolonged durations, then adequate CHO should be provided in the 24 h period prior to and during the specific training session.
Careful day-to-day periodization in a meal-by-meal manner (as opposed to chronic periods of CHO restriction) is likely to maintain metabolic flexibility and still allow for the completion of high-intensity and prolonged duration workloads on heavy training days, e.g., interval type workouts undertaken above lactate threshold. Intuitively, train-low sessions may be best left to training sessions that are not CHO dependent and in which the intensity and duration of the session are not likely to be compromised by reduced CHO availability, e.g., steady-state type training sessions performed at intensities below the lactate threshold.
Clearly, more studies are required to investigate the optimal practical approach for which to integrate periods of train-low into an elite athlete’s training program.
