Effect of Ketogenic and Carbohydrate Diet in Crossfit

The Effect of Ketogenic and Carbohydrate, Low-Glycemic Index Diet on Physical and Specific Performance Capacity, and Exercise Metabolism in Crossfit- Trained Athletes

The purpose of the presented study was to assess the influence of Ketogenic (KD) and a carbohydrate diet with a low glycemic index (CHO-LGI) of a 4-week diet on physical and specific performance capacity, exercise metabolism, as well as concentrations of the selected biochemical blood markers in Crossfit- trained athletes, in a randomised and parallel trial.

Study Overview

• Status: Active, not recruiting
• Conditions: Nutrition; Ketogenic Dieting; Sport; Low Glycemic Index Diet; Crossfit
• Intervention / Treatment: Other: Dietary Intervention - Ketogenic Diet (KD); Other: Dietary Intervention - Low-Glycemic Index Diet (CHO-LGI)

Detailed Description

The impact of various dietary strategies, including the alternative ketogenic diet - recently popular among strength athletes, has not been unequivocally assessed in the high-intensity sport disciplines that Crossfit belongs to. There is also a lack of data in these disciplines about the potential longer adaptation of athletes to the very low carbohydrate intake resulting from the ketogenic diet and its impact in high-intensity Crossfit training. Therefore, the purpose of this study was the assessment of the influence of a 4-week KD and a CHO-LGI diet on physical and specific performance capacity, exercise metabolism, as well as concentrations of the selected biochemical blood markers in Crossfit- trained athletes, in a randomised and parallel trial.

• Study Type: Interventional
• Enrollment (Estimated): 70
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Poland
  • Poznań, Poland, 60-624
    • Institute of Human Nutrition and Dietetics, Poznan University of Life Sciences

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 40 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• written consent to participate,
• a current medical clearance to practice sports,
• training experience: at least 2 years,
• minimum of 4 workout sessions (Crossfit) a week.

Exclusion Criteria:

• current injury,
• any health-related contraindication,
• declared general feeling of being unwell,
• unwilling to follow the study protocol,
• smoking, illicit drug use, alcohol consumption greater than 1-2 drinks/week, dietary supplements use less than 3 weeks before the study,
• females- being pregnant or planning to become pregnant during the study.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Ketogenic Diet (KD); Group consuming very low carbohydrate ketogenic diet. The ketogenic diet model was energetically normalized (covered the estimated energy expenditure) and assumed coverage of the daily energy requirement up to 5% of energy from carbohydrates. Proteins were administered in the amount of 1.7 g per kilogram of body mass. The remaining energy needs were covered with fats (fats covered more than 75% of the daily energy requirement). Each of the subjects in this group received 10-day menus.	Other: Dietary Intervention - Ketogenic Diet (KD); The experimental procedure for each randomly assigned participant included a 4-week of KD diet.
Active Comparator: Low-Glycemic Index Diet (CHO-LGI); Group consuming carbohydrate, low-glycemic index diet. The carbohydrate diet model with a low glycemic index was energetically normalized (covered the estimated energy expenditure) and assumed coverage of the daily energy requirement of 25% of fat. Proteins were administered in the amount of 1.7 g per kilogram of body mass. The remaining energy needs were covered with carbohydrates (carbohydrates covered about ~55% of the daily energy requirement). The glycemic index of individual meals as well as the daily diet was calculated in accordance with the appropriate recommendations. Each of the subjects in this group received 10-day menus.	Other: Dietary Intervention - Low-Glycemic Index Diet (CHO-LGI); The experimental procedure for each randomly assigned participant included a 4-week of CHO-LGI diet.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in aerobic capacity following dietary intervention		Baseline and after 4 weeks
Changes in CrossFit-specific performance capacity (Fight Gone Bad test) following dietary intervention	The number of correctly performed repetitions of exercises (reps)	Baseline and after 4 weeks
Changes in energy substrates utilization following dietary intervention	Fats (g/min) and carbohydrates (g/min) oxidation analysis	Baseline and after 4 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in fat mass and fat free mass following dietary intervention	Fat mass (kg) and fat free mass (kg) analysis	Baseline and after 4 weeks
Changes of red and white blood cell concentration in blood following dietary intervention	Red blood cells (RBC) [mln/mm³] and white blood cells (WBC) [mln/mm³] concentration analysis	Baseline and after 4 weeks
Changes in blood glucose and hemoglobin concentration following dietary intervention	Hemoglobin (Hb) [g/dl] and glucose [g/dl] concentration analysis	Baseline and after 4 weeks
Changes in blood hematocrit levels following dietary intervention	Hematocrit (HCT) [%] level analysis	Baseline and after 4 weeks
Changes of testosterone, cortisol, urea, lactate and pyruvate concentration in blood following dietary intervention	Testosterone [mmol/L], cortisol [mmol/L], urea [mmol/L], lactate [mmol/L] and pyruvate [mmol/L] concentration analysis	Baseline and after 4 weeks
Changes of creatine kinase, lactate dehydrogenase, alanine aminotransferase and aspartate aminotransferase activity in blood after following dietary intervention	Creatine kinase [U/L], lactate dehydrogenase [U/L], alanine aminotransferase [U/L] and aspartate aminotransferase [U/L] activity analysis	Baseline and after 4 weeks

Collaborators and Investigators

• Sponsor: Poznan University of Physical Education
• Collaborators: Poznan University of Life Sciences; Poznan University of PhysED
• Investigators: Study Chair: Jan Jeszka, Professor, Institute of Human Nutrition and Dietetics, Poznan University of Life Sciences

Publications and helpful links

General Publications

• Durkalec-Michalski K, Nowaczyk PM, Siedzik K. Effect of a four-week ketogenic diet on exercise metabolism in CrossFit-trained athletes. J Int Soc Sports Nutr. 2019 Apr 5;16(1):16. doi: 10.1186/s12970-019-0284-9.

Study record dates

Study Major Dates

• Study Start (Actual): January 9, 2017
• Primary Completion (Estimated): November 1, 2024
• Study Completion (Estimated): December 20, 2024

Study Registration Dates

• First Submitted: September 5, 2018
• First Submitted That Met QC Criteria: September 7, 2018
• First Posted (Actual): September 11, 2018

Study Record Updates

• Last Update Posted (Actual): May 16, 2024
• Last Update Submitted That Met QC Criteria: May 14, 2024
• Last Verified: May 1, 2024

More Information

Terms related to this study

• Keywords: Performance; Ketogenic Diet; Physical capacity; Training support; Low Glycemic Index Diet; Crossfit; Sports Nutrition; Exercise metabolism
• Other Study ID Numbers: ULS00004

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: Shared data will be exclusively related to the level recorded indicators (anaerobic capacity and specific performance capacity indicators, exercise metabolism, levels of biochemical markers, and body composition), without personal data. The data obtained will be attached to scientific publications, depending on the requirements of the journal.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No