Kleiner Marcio De Andrade Nemezio1, Romulo Bertuzzi, Carlos Rafaell Correia-Oliveira, Bruno Gualano, David John Bishop, Adriano Eduardo Lima-Silva. 1. 1Sports Science Research Group, Department of Physical Education and Sports Science CAV, Federal University of Pernambuco, BRAZIL; 2Endurance Performance Research Group, School of Physical Education and Sport, University of São Paulo, São Paulo, BRAZIL; 3School of Physical Education and Sport, University of São Paulo, BRAZIL; 4Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, AUSTRALIA.
Abstract
PURPOSE: For the first time, we investigated the effects of altering cellular metabolic capacitance, via a 5-d creatine (Cr) loading protocol (20 g·d⁻¹), on oxygen uptake (VO2), accumulated oxygen deficit, muscle recruitment, and performance during a 1-km cycling time trial. METHODS: In a double-blind, randomized, placebo-controlled design, 19 amateur cyclists were allocated to a Cr (n = 10, VO2peak = 56.0 ± 7.8 mL·kg⁻¹·min⁻¹) or placebo (n = 9, VO2peak = 56.0 ± 8.4 mL·kg⁻¹·min⁻¹) group, and performed a 1-km cycling time trial before and after the supplementation period. RESULTS:Body mass was significantly increased in the Cr group (P < 0.05), but not in the placebo group. Participants adopted an "all-out" pacing strategy in both groups. However, Cr loading reduced VO2 immediately after the beginning (12th to 23th seconds), and this was accompanied by a reduced aerobic and increased anaerobic contribution. The VO2 mean response time was slower (pre: 17.2 ± 5.6 s vs post: 19.9 ± 4.6 s), the total O2 uptake was reduced (pre: 4.64 ± 0.59 L vs post: 4.47 ± 0.53 L), and the oxygen deficit was increased (pre: 0.82 ± 0.27 L vs post: 0.98 ± 0.25 L) after Cr loading. No differences were observed in the placebo group for these variables. Plasma lactate and integrated electromyography were not altered in either group, nor was the time to complete the trial (Cr group: pre: 89.1 ± 6.7 s vs post 89.1 ± 6.2 s and placebo group: pre 85.9 ± 4.9 s vs post 87.0 ± 5.4 s). CONCLUSION: Cr loading slows the V˙O2 response and increases the anaerobic contribution during a 1-km cycling time trial.
RCT Entities:
PURPOSE: For the first time, we investigated the effects of altering cellular metabolic capacitance, via a 5-d creatine (Cr) loading protocol (20 g·d⁻¹), on oxygen uptake (VO2), accumulated oxygen deficit, muscle recruitment, and performance during a 1-km cycling time trial. METHODS: In a double-blind, randomized, placebo-controlled design, 19 amateur cyclists were allocated to a Cr (n = 10, VO2peak = 56.0 ± 7.8 mL·kg⁻¹·min⁻¹) or placebo (n = 9, VO2peak = 56.0 ± 8.4 mL·kg⁻¹·min⁻¹) group, and performed a 1-km cycling time trial before and after the supplementation period. RESULTS: Body mass was significantly increased in the Cr group (P < 0.05), but not in the placebo group. Participants adopted an "all-out" pacing strategy in both groups. However, Cr loading reduced VO2 immediately after the beginning (12th to 23th seconds), and this was accompanied by a reduced aerobic and increased anaerobic contribution. The VO2 mean response time was slower (pre: 17.2 ± 5.6 s vs post: 19.9 ± 4.6 s), the total O2 uptake was reduced (pre: 4.64 ± 0.59 L vs post: 4.47 ± 0.53 L), and the oxygen deficit was increased (pre: 0.82 ± 0.27 L vs post: 0.98 ± 0.25 L) after Cr loading. No differences were observed in the placebo group for these variables. Plasma lactate and integrated electromyography were not altered in either group, nor was the time to complete the trial (Cr group: pre: 89.1 ± 6.7 s vs post 89.1 ± 6.2 s and placebo group: pre 85.9 ± 4.9 s vs post 87.0 ± 5.4 s). CONCLUSION:Cr loading slows the V˙O2 response and increases the anaerobic contribution during a 1-km cycling time trial.
Authors: Diego A Bonilla; Richard B Kreider; Jeffrey R Stout; Diego A Forero; Chad M Kerksick; Michael D Roberts; Eric S Rawson Journal: Nutrients Date: 2021-04-09 Impact factor: 5.717
Authors: Benjamin Wax; Chad M Kerksick; Andrew R Jagim; Jerry J Mayo; Brian C Lyons; Richard B Kreider Journal: Nutrients Date: 2021-06-02 Impact factor: 5.717