Periodized carbohydrate intake influences metabolic flexibility and indices of running economy during endurance training in recreationally active males

Purpose:

Limited research has explored the long-term impact of diet periodization on metabolism, performance, and body composition. This eight-week study examined the effects of long-term periodized carbohydrate (CHO) intake on performance, substrate utilization, and body composition in recreationally active males.

Methods:

Twenty-four runners (V̇O2 peak: 51 ± 8 mL·min−1·kg−1) were randomly assigned to one nutritional intervention: (1) PER: 4 weeks of ≤ 50 g CHO per day followed by 4 weeks of high CHO; (2) LCHF: 8 weeks of ≤ 50 g CHO per day; or (3) CHO: 8 weeks of high CHO. All subjects underwent the same endurance training. Performance and substrate use were measured using a graded exercise test at baseline (T-0), after 4 weeks (T-1), and after 8 weeks (T-2). Body weight and composition were measured using bioelectrical impedance analysis.

Results:

While performance improved over time, no significant differences were found between groups. However, running economy at lactate threshold only improved in the PER group (p     https://doi.org/10.17605/OSF.IO/VM7KB

This study examines the effects of periodized carbohydrate intake on performance and metabolic flexibility.