Mixed
Periodizing carbohydrate intake by performing high-intensity training with high carbohydrate availability followed by overnight restriction ('sleeping low') and subsequent low-intensity training with low carbohydrate availability significantly improves 10 km running performance and submaximal cycling efficiency in trained endurance athletes compared to maintaining high carbohydrate availability throughout.
If you are a trained endurance athlete, try a 'Sleep Low' strategy for 3 weeks. Keep your total daily carbohydrate intake the same (around 6g/kg), but change when you eat it. Eat high carbohydrates before and after your hardest workouts (like intervals). Then, skip carbohydrates after that workout and do not eat them during your next morning's easy, low-intensity workout. This may improve your running speed and cycling efficiency without reducing your overall training volume or intensity.
Short-term periodization of dietary CHO availability around selected training sessions promoted significant improvements in submaximal cycling economy, as well as supra-maximal cycling capacity and 10 km running time in trained endurance athletes.
Why this rating
Randomized controlled trial with trained athletes, clear intervention and control groups, and statistically significant performance outcomes, though sample size is modest (n=21).
Source
Enhanced Endurance Performance by Periodization of Carbohydrate Intake
Laurie-Anne Marquet et al. · Medicine & Science in Sports & Exercise · 2016
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