TY - JOUR

T1 - No superior adaptations to carbohydrate periodization in elite endurance athletes

AU - Gejl, Kasper Degn

AU - Thams, Line

AU - Hansen, Mette

AU - Lausch, Torben Rokkedal

AU - Plomgaard, Peter

AU - Nybo, Lars

AU - Larsen, Filip J

AU - Cardinale, Daniele A

AU - Jensen, Kurt

AU - Holmberg, Hans-Christer

AU - Vissing, Kristian

AU - Ørtenblad, Niels

N1 - CURIS 2017 NEXS 315

PY - 2017

Y1 - 2017

N2 - Purpose: The present study investigated the effects of periodic carbohydrate (CHO) restriction on endurance performance and metabolic markers in elite endurance athletes.Methods: Twenty-six male elite endurance athletes (maximal oxygen consumption (V·O2max), 65.0 ml O2•kg-1•min-1) completed 4 wk of regular endurance training while being matched and randomized into two groups training with (low) or without (high) CHO manipulation 3 d•wk-1. The CHO manipulation days consisted of a 1-h high-intensity bike session in the morning, recovery for 7 h while consuming isocaloric diets containing either high CHO (414±2.4 g) or low CHO (79.5±1.0 g), and a 2-hr moderate bike session in the afternoon with or without CHO. V·O2max, maximal fat oxidation, and power output during a 30-min time trial (TT) were determined before and after the training period. The TT was undertaken after 90 min of intermittent exercise with CHO provision before the training period and both CHO and placebo after the training period. Muscle biopsies were analyzed for glycogen, citrate synthase (CS) and β-hydroxyacyl-coenzyme A dehydrogenase (HAD) activity, carnitine palmitoyltransferase (CPT1b), and phosphorylated acetyl-CoA carboxylase (pACC).Results: The training effects were similar in both groups for all parameters. On average, V·O2max and power output during the 30-min TT increased by 5 ± 1% (P < 0.05) and TT performance was similar after CHO and placebo during the preload phase. Training promoted overall increases in glycogen content (18% ± 5%), CS activity (11% ± 5%) and pACC (38% ± 19%) (P < 0.05) with no differences between groups. HAD activity and CPT1b protein content remained unchanged.Conclusion: Superimposing periodic CHO restriction to 4 wk of regular endurance training had no superior effects on performance and muscle adaptations in elite endurance athletes.

AB - Purpose: The present study investigated the effects of periodic carbohydrate (CHO) restriction on endurance performance and metabolic markers in elite endurance athletes.Methods: Twenty-six male elite endurance athletes (maximal oxygen consumption (V·O2max), 65.0 ml O2•kg-1•min-1) completed 4 wk of regular endurance training while being matched and randomized into two groups training with (low) or without (high) CHO manipulation 3 d•wk-1. The CHO manipulation days consisted of a 1-h high-intensity bike session in the morning, recovery for 7 h while consuming isocaloric diets containing either high CHO (414±2.4 g) or low CHO (79.5±1.0 g), and a 2-hr moderate bike session in the afternoon with or without CHO. V·O2max, maximal fat oxidation, and power output during a 30-min time trial (TT) were determined before and after the training period. The TT was undertaken after 90 min of intermittent exercise with CHO provision before the training period and both CHO and placebo after the training period. Muscle biopsies were analyzed for glycogen, citrate synthase (CS) and β-hydroxyacyl-coenzyme A dehydrogenase (HAD) activity, carnitine palmitoyltransferase (CPT1b), and phosphorylated acetyl-CoA carboxylase (pACC).Results: The training effects were similar in both groups for all parameters. On average, V·O2max and power output during the 30-min TT increased by 5 ± 1% (P < 0.05) and TT performance was similar after CHO and placebo during the preload phase. Training promoted overall increases in glycogen content (18% ± 5%), CS activity (11% ± 5%) and pACC (38% ± 19%) (P < 0.05) with no differences between groups. HAD activity and CPT1b protein content remained unchanged.Conclusion: Superimposing periodic CHO restriction to 4 wk of regular endurance training had no superior effects on performance and muscle adaptations in elite endurance athletes.

KW - Diet manipulation

KW - Glycogen

KW - Enzyme activity

KW - Triathletes

KW - Endurance performance

U2 - 10.1249/MSS.0000000000001377

DO - 10.1249/MSS.0000000000001377

M3 - Journal article

C2 - 28723843

VL - 49

SP - 2486

EP - 2497

JO - Medicine and Science in Sports and Exercise

JF - Medicine and Science in Sports and Exercise

SN - 0195-9131

IS - 12

ER -