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Vargas-Molina S, García-Sillero M, Bonilla DA, Petro JL, García-Romero J, Benítez-Porres J. The effect of the ketogenic diet on resistance training load management: a repeated-measures clinical trial in trained participants. J Int Soc Sports Nutr 2024; 21:2306308. [PMID: 38285913 PMCID: PMC10826788 DOI: 10.1080/15502783.2024.2306308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 01/11/2024] [Indexed: 01/31/2024] Open
Abstract
BACKGROUND The effect of low-carbohydrate high-fat dietary manipulation, such as the ketogenic diet (KD), on muscle strength assessment in resistance-training (RT) participants has focused on the one-repetition maximum test (1-RM). However, a pre-specified 1-RM value during an exercise training program disregards several confounding factors (i.e. sleep, diet, and training-induced fatigue) that affect the exerciser's "true" load and daily preparedness. We aimed to evaluate the effect of a 6-week RT program on load control-related variables in trained subjects following a KD intervention. METHODS Fourteen resistance-trained individuals (3F, 11 M; 30.1 [6.2] years; 174.2 [7.6] cm; 75.7 [10.8] kg; BMI 24.8 [2.1] kg·m-2) completed this single-arm repeated-measures clinical trial. Load management variables included volume load, number of repetitions, perceived exertion (RPE), movement velocity loss, and exertion index. These primary outcomes were assessed weekly before, during, and at the end of a 6-week RT program that included traditional RT exercises (bench press, femoral lying down, lat pulldown, leg extension, and back squat). RESULTS There was a significant difference in RPE between weeks (p = 0.015, W = 0.19) with a slight trend in decreasing RPE. We found differences in the volume load per week (p < 0.001; W = 0.73 and p < 0.001, W = 0.81, respectively), with an increase in the last weeks. In the control of the load based on movement velocity, we did not find significant differences between weeks (p = 0.591, W = 0.06), although significant differences were found in the effort index (p = 0.026, W = 0.17). CONCLUSIONS A KD diet in recreational strength participants does not appear to lead to performance losses during a RT program aimed at improving body composition. However, the lack of adherence and familiarity with the ketogenic diet must be considered specially during first weeks.
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Affiliation(s)
- Salvador Vargas-Molina
- University of Málaga, Physical education and sport area, Faculty of Medicine, Málaga, Spain
- Physical education and sport, EADE-University of Wales Trinity Saint David, Málaga, Spain
| | - Manuel García-Sillero
- Physical education and sport, EADE-University of Wales Trinity Saint David, Málaga, Spain
| | - Diego A. Bonilla
- Dynamical Business & Science Society – DBSS International SAS, Research Division, Bogotá, Colombia
- Universidad de Córdoba, Research Group in Physical Activity, Sports and Health Sciences (GICAFS), Montería, Colombia
| | - Jorge L. Petro
- Dynamical Business & Science Society – DBSS International SAS, Research Division, Bogotá, Colombia
- Universidad de Córdoba, Research Group in Physical Activity, Sports and Health Sciences (GICAFS), Montería, Colombia
| | - Jerónimo García-Romero
- University of Málaga, Physical education and sport area, Faculty of Medicine, Málaga, Spain
| | - Javier Benítez-Porres
- University of Málaga, Physical education and sport area, Faculty of Medicine, Málaga, Spain
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2
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Leaf A, Rothschild JA, Sharpe TM, Sims ST, Macias CJ, Futch GG, Roberts MD, Stout JR, Ormsbee MJ, Aragon AA, Campbell BI, Arent SM, D’Agostino DP, Barrack MT, Kerksick CM, Kreider RB, Kalman DS, Antonio J. International society of sports nutrition position stand: ketogenic diets. J Int Soc Sports Nutr 2024; 21:2368167. [PMID: 38934469 PMCID: PMC11212571 DOI: 10.1080/15502783.2024.2368167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Accepted: 06/11/2024] [Indexed: 06/28/2024] Open
Abstract
POSITION STATEMENT The International Society of Sports Nutrition (ISSN) provides an objective and critical review of the use of a ketogenic diet in healthy exercising adults, with a focus on exercise performance and body composition. However, this review does not address the use of exogenous ketone supplements. The following points summarize the position of the ISSN. 1. A ketogenic diet induces a state of nutritional ketosis, which is generally defined as serum ketone levels above 0.5 mM. While many factors can impact what amount of daily carbohydrate intake will result in these levels, a broad guideline is a daily dietary carbohydrate intake of less than 50 grams per day. 2. Nutritional ketosis achieved through carbohydrate restriction and a high dietary fat intake is not intrinsically harmful and should not be confused with ketoacidosis, a life-threatening condition most commonly seen in clinical populations and metabolic dysregulation. 3. A ketogenic diet has largely neutral or detrimental effects on athletic performance compared to a diet higher in carbohydrates and lower in fat, despite achieving significantly elevated levels of fat oxidation during exercise (~1.5 g/min). 4. The endurance effects of a ketogenic diet may be influenced by both training status and duration of the dietary intervention, but further research is necessary to elucidate these possibilities. All studies involving elite athletes showed a performance decrement from a ketogenic diet, all lasting six weeks or less. Of the two studies lasting more than six weeks, only one reported a statistically significant benefit of a ketogenic diet. 5. A ketogenic diet tends to have similar effects on maximal strength or strength gains from a resistance training program compared to a diet higher in carbohydrates. However, a minority of studies show superior effects of non-ketogenic comparators. 6. When compared to a diet higher in carbohydrates and lower in fat, a ketogenic diet may cause greater losses in body weight, fat mass, and fat-free mass, but may also heighten losses of lean tissue. However, this is likely due to differences in calorie and protein intake, as well as shifts in fluid balance. 7. There is insufficient evidence to determine if a ketogenic diet affects males and females differently. However, there is a strong mechanistic basis for sex differences to exist in response to a ketogenic diet.
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Affiliation(s)
- Alex Leaf
- Alex Leaf LLC, Scientific Affairs, Scottsdale, AZ, USA
| | - Jeffrey A. Rothschild
- Auckland University of Technology, Sports Performance Research Institute New Zealand, Auckland, New Zealand
- High Performance Sport New Zealand, Performance Nutrition, Auckland, New Zealand
| | - Tim M. Sharpe
- University of Western States, Human Nutrition and Functional Medicine, Portland, OR, USA
| | - Stacy T. Sims
- Auckland University of Technology, Sports Performance Research Institute New Zealand, Auckland, New Zealand
- Stanford University, Stanford Lifestyle Medicine, Palo Alto, CA, USA
| | - Chad J. Macias
- University of Western States, Human Nutrition and Functional Medicine, Portland, OR, USA
| | - Geoff G. Futch
- Springfield College, Department of Exercise Science and Athletic Training, Springfield, MA, USA
- FitPro Analytics, Scientific Affairs, Springfield, MA, USA
| | | | - Jeffrey R. Stout
- University of Central Florida, School of Kinesiology and Rehabilitation Sciences, Orlando, FL, USA
| | - Michael J. Ormsbee
- Florida State University, Institute of Sports Sciences & Medicine, Tallahassee, FL, USA
- University of KwaZulu Natal, Discipline of Biokinetics, Exercise and Leisure Sciences, Durban, South Africa
| | | | - Bill I. Campbell
- University of South Florida, Performance and Physique Enhancement Laboratory, Exercise Science Program, Tampa, FL, USA
| | - Shawn M. Arent
- University of South Carolina, Department of Exercise Science, Arnold School of Public Health, Columbia, SC, USA
| | - Dominic P. D’Agostino
- Institute for Human and Machine Cognition, Human Healthspan, Resilience, and Performance, Pensacola, FL, USA
- University of South Florida, Department of Molecular Pharmacology and Physiology, Tampa, FL, USA
| | - Michelle T. Barrack
- California State University, Department of Family and Consumer Sciences, Long Beach, CA, USA
| | - Chad M. Kerksick
- Lindenwood University, Exercise and Performance Nutrition Laboratory, College of Science, Technology, and Health, St. Charles, MO, USA
| | - Richard B. Kreider
- Texas A&M University, Exercise and Sport Nutrition Lab, Department of Kinesiology and Sports Management, College Station, TX, USA
| | - Douglas S. Kalman
- Nova Southeastern University, Department of Nutrition. Dr. Kiran C. Patel College of Osteopathic Medicine. Davie, FL, USA
| | - Jose Antonio
- Department of Health and Human Performance, Nova Southeastern University, Davie, FL, USA
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3
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Moitzi AM, Krššák M, Klepochova R, Triska C, Csapo R, König D. Effects of a 10-Week Exercise and Nutritional Intervention with Variable Dietary Carbohydrates and Glycaemic Indices on Substrate Metabolism, Glycogen Storage, and Endurance Performance in Men: A Randomized Controlled Trial. SPORTS MEDICINE - OPEN 2024; 10:36. [PMID: 38600291 PMCID: PMC11006643 DOI: 10.1186/s40798-024-00705-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 03/24/2024] [Indexed: 04/12/2024]
Abstract
BACKGROUND Daily nutrition plays an important role in supporting training adaptions and endurance performance. The objective of this 10-week study was to investigate the consequences of varying carbohydrate consumption and the glycaemic index (GI) together with an endurance training regimen on substrate oxidation, muscle energy storage and endurance performance under free-living conditions. Sixty-five moderately trained healthy men (29 ± 4 years; VO2 peak 55 ± 8 mL min-1 kg-1) were randomized to one of three different nutritional regimes (LOW-GI: 50-60% CHO with ≥ 65% of these CHO with GI < 50 per day, n = 24; HIGH-GI: 50-60% CHO with ≥ 65% CHO with GI > 70 per day, n = 20; LCHF: ≤ 50 g CHO daily, n = 21). Metabolic alterations and performance were assessed at baseline (T0) and after 10 weeks (T10) during a graded exercise treadmill test. Additionally, a 5 km time trial on a 400-m outdoor track was performed and muscle glycogen was measured by magnet resonance spectroscopy. RESULTS Total fat oxidation expressed as area under the curve (AUC) during the graded exercise test increased in LCHF (1.3 ± 2.4 g min-1 × km h-1, p < 0.001), remained unchanged in LOW-GI (p > 0.05) and decreased in HIGH-GI (- 1.7 ± 1.5 g min-1 × km h-1, p < 0.001). After the intervention, LOW-GI (- 0.4 ± 0.5 mmol L-1 × km h-1, p < 0.001) and LCHF (- 0.8 ± 0.7 mmol L-1 × km h-1, p < 0.001) showed significantly lower AUC of blood lactate concentrations. Peak running speed increased in LOW-GI (T0: 4.3 ± 0.4 vs. T10: 4.5 ± 0.3 m s-1, p < 0.001) and HIGH-GI (T0: 4.4 ± 0.5 vs. T10: 4.6 ± 0.4 m s-1), while no improvement was observed in LCHF. Yet, time trial performance improved significantly in all groups. Muscle glycogen content increased for participants in HIGH-GI (T0: 97.3 ± 18.5 vs. T10: 144.5 ± 39.8 mmol L wet-tissue-1, p = 0.027) and remained unchanged in the LOW-GI and the LCHF group. At the last examination, muscle glycogen concentration was significantly higher in LOW-GI compared to LCHF (p = 0.014). CONCLUSION Changes in fat oxidation were only present in LCHF, however, lower lactate concentrations in LOW-GI resulted in changes indicating an improved substrate metabolism. Compared to a LCHF diet, changes in peak running speed, and muscle glycogen stores were superior in LOW- and HIGH-GI diets. The low GI diet seems to have an influence on substrate metabolism without compromising performance at higher intensities, suggesting that a high-carbohydrate diet with a low GI is a viable alternative to a LCHF or a high GI diet. TRIAL REGISTRATION Clinical Trials, NCT05241730. https://clinicaltrials.gov/study/NCT05241730 . Registered 25 January 2021.
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Affiliation(s)
- Anna Maria Moitzi
- Division of Nutrition, Exercise and Health, Department of Nutritional Sciences, Faculty of Life Sciences, University of Vienna, Vienna, Austria.
- Vienna Doctoral School of Pharmaceutical, Nutritional and Sport Sciences, University of Vienna, Vienna, Austria.
- Division of Nurtition, Exercise and Health, Department of Sport and Human Movement Science, University of Vienna, Vienna, Austria.
| | - Martin Krššák
- Department of Biomedical Imaging and Image Guided Therapy, High Field MR Centre of Excellence, Medical University of Vienna, Vienna, Austria
- Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Radka Klepochova
- Department of Biomedical Imaging and Image Guided Therapy, High Field MR Centre of Excellence, Medical University of Vienna, Vienna, Austria
- Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Christoph Triska
- Leistungssport Austria, High Performance Centre, Brunn am Gebirge, Lower Austria, Austria
- Division of Training Science, Department of Sport and Human Movement Science, University of Vienna, Vienna, Austria
| | - Robert Csapo
- Division of Training Science, Department of Sport and Human Movement Science, University of Vienna, Vienna, Austria
| | - Daniel König
- Division of Nutrition, Exercise and Health, Department of Nutritional Sciences, Faculty of Life Sciences, University of Vienna, Vienna, Austria
- Division of Nurtition, Exercise and Health, Department of Sport and Human Movement Science, University of Vienna, Vienna, Austria
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4
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Burke LM, Whitfield J. Ketogenic Diets Are Not Beneficial for Athletic Performance: Response to Noakes. Med Sci Sports Exerc 2024; 56:763-765. [PMID: 38485731 DOI: 10.1249/mss.0000000000003346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Affiliation(s)
- Louise M Burke
- Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, AUSTRALIA
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5
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Moitzi AM, König D. Longer-Term Effects of the Glycaemic Index on Substrate Metabolism and Performance in Endurance Athletes. Nutrients 2023; 15:3028. [PMID: 37447354 DOI: 10.3390/nu15133028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 06/29/2023] [Accepted: 07/02/2023] [Indexed: 07/15/2023] Open
Abstract
Nutrition has a decisive influence on athletic performance. However, it is not only the nutrient intake during exercise that is important, but the daily diet must also be adapted to the requirements of physical activity in order to optimally promote training adaptations. The goal of prolonged endurance training is to enhance fat oxidation, to maintain aerobic performance at a higher intensity while sparing limited carbohydrate stores. The targeted modification of macronutrient intake is a common method of influencing substrate metabolism, fuel selection, and performance. However, it is not well established whether the glycaemic index of carbohydrates in our daily diet can improve endurance performance by influencing carbohydrate or fat oxidation during training. Therefore, the aim of the following review is to elucidate the possible influence of the glycaemic index on substrate utilization during exercise and to clarify whether the consumption of a long-term high-carbohydrate diet with different glycaemic indices may have an influence on substrate metabolism and endurance performance.
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Affiliation(s)
- Anna Maria Moitzi
- Division for Nutrition, Exercise and Health, Department of Nutritional Sciences, Faculty of Life Sciences, University of Vienna, 1090 Vienna, Austria
- Vienna Doctoral School of Pharmaceutical, Nutritional and Sport Sciences, University of Vienna, 1090 Vienna, Austria
| | - Daniel König
- Division for Nutrition, Exercise and Health, Department of Nutritional Sciences, Faculty of Life Sciences, University of Vienna, 1090 Vienna, Austria
- Division for Nutrition, Exercise and Health, Department of Sport Science, Centre for Sports Science and University Sports, University of Vienna, 1150 Vienna, Austria
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6
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Chiarello N, Leger B, De Riedmatten M, Rossier MF, Vuistiner P, Duc M, Rapillard A, Allet L. Effect of a four-week isocaloric ketogenic diet on physical performance at very high-altitude: a pilot study. BMC Sports Sci Med Rehabil 2023; 15:37. [PMID: 36941621 PMCID: PMC10029223 DOI: 10.1186/s13102-023-00649-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 03/13/2023] [Indexed: 03/23/2023]
Abstract
BACKGROUND A ketogenic diet (KD) reduces daily carbohydrates (CHOs) ingestion by replacing most calories with fat. KD is of increasing interest among athletes because it may increase their maximal oxygen uptake (VO2max), the principal performance limitation at high-altitudes (1500-3500 m). We examined the tolerance of a 4-week isocaloric KD (ICKD) under simulated hypoxia and the possibility of evaluating ICKD performance benefits with a maximal graded exercise bike test under hypoxia and collected data on the effect of the diet on performance markers and arterial blood gases. METHODS In a randomised single-blind cross-over model, 6 recreational mountaineers (age 24-44 years) completed a 4-week ICKD followed or preceded by a 4-week usual mixed Western-style diet (UD). Performance parameters (VO2max, lactate threshold [LT], peak power [Ppeak]) and arterial blood gases (PaO2, PaCO2, pH, HCO3-) were measured at baseline under two conditions (normoxia and hypoxia) as well as after a 4-week UD and 4-week ICKD under the hypoxic condition. RESULTS We analysed data for all 6 participants (BMI 19.9-24.6 kg m-2). Mean VO2max in the normoxic condition was 44.6 ml kg-1 min-1. Hypoxia led to decreased performance in all participants. With the ICKD diet, median values for PaO2 decreased by - 14.5% and VO2max by + 7.3% and Ppeak by + 4.7%. CONCLUSION All participants except one could complete the ICKD. VO2max improved with the ICKD under the hypoxia condition. Therefore, an ICKD is an interesting alternative to CHOs dependency for endurance performance at high-altitudes, including high-altitude training and high-altitude races. Nevertheless, decreased PaO2 with ICKD remains a significant limitation in very-high to extreme altitudes (> 3500 m). Trial registration Clinical trial registration Nr. NCT05603689 (Clinicaltrials.gov). Ethics approval CER-VD, trial Nr. 2020-00427, registered 18.08.2020-prospectively registered.
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Affiliation(s)
- Nicolas Chiarello
- Department of Medicine, University Hospitals of Geneva, University of Geneva, Geneva, Switzerland.
| | | | | | - Michel F Rossier
- Service of Clinical Chemistry and Toxicology, Central Institute of the Hospitals - HVS, Sion, Switzerland
- Department of Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Philippe Vuistiner
- Institute for Research in Rehabilitation, Clinique romande de réadaptation, Sion, Switzerland
| | - Michael Duc
- Swiss Olympic Medical Center, Clinique romande de réadaptation, Sion, Switzerland
| | - Arnaud Rapillard
- Swiss Olympic Medical Center, Clinique romande de réadaptation, Sion, Switzerland
| | - Lara Allet
- Department of Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
- Valais-Wallis School of Health Sciences, HES-SO, University of Applied Sciences and Arts Western Switzerland, Valais, Switzerland
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7
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Sharp DW, Swain JC, Boy TG, Killen LG, Green JM, O'Neal EK. Effects of 2.4 kg of Proximal External Loading on 5-km Running Performance. J Strength Cond Res 2022; 36:1833-1838. [DOI: 10.1519/jsc.0000000000003722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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8
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Moreno-Villanueva A, Rico-González M, Pino-Ortega J. The Effects of a Ketogenic Diet on Anthropometric Parameters, Metabolic Adaptation, and Physical Fitness Performance in Amateur Endurance Athletes: A Systematic Review. Strength Cond J 2022. [DOI: 10.1519/ssc.0000000000000647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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9
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Noakes TD. What Is the Evidence That Dietary Macronutrient Composition Influences Exercise Performance? A Narrative Review. Nutrients 2022; 14:862. [PMID: 35215511 PMCID: PMC8875928 DOI: 10.3390/nu14040862] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 01/25/2022] [Accepted: 01/25/2022] [Indexed: 01/06/2023] Open
Abstract
The introduction of the needle muscle biopsy technique in the 1960s allowed muscle tissue to be sampled from exercising humans for the first time. The finding that muscle glycogen content reached low levels at exhaustion suggested that the metabolic cause of fatigue during prolonged exercise had been discovered. A special pre-exercise diet that maximized pre-exercise muscle glycogen storage also increased time to fatigue during prolonged exercise. The logical conclusion was that the athlete's pre-exercise muscle glycogen content is the single most important acutely modifiable determinant of endurance capacity. Muscle biochemists proposed that skeletal muscle has an obligatory dependence on high rates of muscle glycogen/carbohydrate oxidation, especially during high intensity or prolonged exercise. Without this obligatory carbohydrate oxidation from muscle glycogen, optimum muscle metabolism cannot be sustained; fatigue develops and exercise performance is impaired. As plausible as this explanation may appear, it has never been proven. Here, I propose an alternate explanation. All the original studies overlooked one crucial finding, specifically that not only were muscle glycogen concentrations low at exhaustion in all trials, but hypoglycemia was also always present. Here, I provide the historical and modern evidence showing that the blood glucose concentration-reflecting the liver glycogen rather than the muscle glycogen content-is the homeostatically-regulated (protected) variable that drives the metabolic response to prolonged exercise. If this is so, nutritional interventions that enhance exercise performance, especially during prolonged exercise, will be those that assist the body in its efforts to maintain the blood glucose concentration within the normal range.
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Affiliation(s)
- Timothy David Noakes
- Department of Applied Design, Cape Peninsula University of Technology, Cape Town 8000, South Africa
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10
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Cao J, Lei S, Wang X, Cheng S. The Effect of a Ketogenic Low-Carbohydrate, High-Fat Diet on Aerobic Capacity and Exercise Performance in Endurance Athletes: A Systematic Review and Meta-Analysis. Nutrients 2021; 13:2896. [PMID: 34445057 PMCID: PMC8400555 DOI: 10.3390/nu13082896] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 08/02/2021] [Accepted: 08/19/2021] [Indexed: 12/29/2022] Open
Abstract
A low-carbohydrate, high-fat (LCHF) diet has been proposed to enhance the fat utilization of muscle and the aerobic capacity of endurance athletes, thereby improving their exercise performance. However, it remains uncertain how the macronutrient intake shift from carbohydrate to fat affects endurance exercise training and performance. This study performed a systematic review and meta-analysis to explore the effects of a ketogenic low-carbohydrate, high-fat (K-LCHF) diet on aerobic capacity and exercise performance among endurance athletes. Searches were carried out in five electronic databases, and we followed the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. The search included studies using an LCHF diet as an intervention protocol and compared data on factors such as maximum oxygen uptake (VO2max) and rating of perceived exertion (RPE) from the graded exercise test. In this case, 10 studies met the criteria and were included in the meta-analysis. We did not find a significant effect of K-LCHF diet interventions on VO2max, time to exhaustion, HRmax or RPE. However, a significant overall effect in the substrate oxidation response to respiratory exchange rate was observed. The meta-analysis showed that K-LCHF diets did not affect aerobic capacity and exercise performance. Therefore, high-quality interventions of a K-LCHF diet are needed to illustrate its effect on various endurance training programs.
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Affiliation(s)
- Jingguo Cao
- Exercise, Health and Technology Centre, Department of Physical Education, Shanghai Jiao Tong University, Shanghai 200240, China; (J.C.); (S.L.); (S.C.)
| | - Siman Lei
- Exercise, Health and Technology Centre, Department of Physical Education, Shanghai Jiao Tong University, Shanghai 200240, China; (J.C.); (S.L.); (S.C.)
- Faculty of Education, University of Macau, Macau SAR, China
| | - Xiuqiang Wang
- Exercise, Health and Technology Centre, Department of Physical Education, Shanghai Jiao Tong University, Shanghai 200240, China; (J.C.); (S.L.); (S.C.)
- Exercise Translational Medicine Centre, Shanghai Centre for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Sulin Cheng
- Exercise, Health and Technology Centre, Department of Physical Education, Shanghai Jiao Tong University, Shanghai 200240, China; (J.C.); (S.L.); (S.C.)
- Exercise Translational Medicine Centre, Shanghai Centre for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai 200240, China
- Faculty of Sport and Health Science, University of Jyväskylä, 40014 Jyväskylä, Finland
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11
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Coleman JL, Carrigan CT, Margolis LM. Body composition changes in physically active individuals consuming ketogenic diets: a systematic review. J Int Soc Sports Nutr 2021; 18:41. [PMID: 34090453 PMCID: PMC8180141 DOI: 10.1186/s12970-021-00440-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 05/11/2021] [Indexed: 12/28/2022] Open
Abstract
Background To achieve ideal strength/power to mass ratio, athletes may attempt to lower body mass through reductions in fat mass (FM), while maintaining or increasing fat-free mass (FFM) by manipulating their training regimens and diets. Emerging evidence suggests that consumption of high-fat, ketogenic diets (KD) may be advantageous for reducing body mass and FM, while retaining FFM. Methods A systematic review of the literature was conducted using PubMed and Cochrane Library databases to compare the effects of KD versus control diets (CON) on body mass and composition in physically active populations. Randomized and non-randomized studies were included if participants were healthy (free of chronic disease), physically active men or women age ≥ 18 years consuming KD (< 50 g carbohydrate/d or serum or whole blood β-hydroxybutyrate (βhb) > 0.5 mmol/L) for ≥14 days. Results Thirteen studies (9 parallel and 4 crossover/longitudinal) that met the inclusion criteria were identified. Aggregated results from the 13 identified studies show body mass decreased 2.7 kg in KD and increased 0.3 kg in CON. FM decreased by 2.3 kg in KD and 0.3 kg in CON. FFM decreased by 0.3 kg in KD and increased 0.7 kg in CON. Estimated energy balance based on changes in body composition was − 339 kcal/d in KD and 5 kcal/d in CON. Risk of bias identified some concern of bias primarily due to studies which allowed participants to self-select diet intervention groups, as well as inability to blind participants to the study intervention, and/or longitudinal study design. Conclusion KD can promote mobilization of fat stores to reduce FM while retaining FFM. However, there is variance in results of FFM across studies and some risk-of-bias in the current literature that is discussed in this systematic review. Supplementary Information The online version contains supplementary material available at 10.1186/s12970-021-00440-6.
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Affiliation(s)
- Julie L Coleman
- U.S. Army Research Institute of Environmental Medicine, 10 General Greene Ave, Building 42, Natick, MA, 01760, USA.,Oak Ridge Institute of Science and Education, Belcamp, MD, USA
| | - Christopher T Carrigan
- U.S. Army Research Institute of Environmental Medicine, 10 General Greene Ave, Building 42, Natick, MA, 01760, USA
| | - Lee M Margolis
- U.S. Army Research Institute of Environmental Medicine, 10 General Greene Ave, Building 42, Natick, MA, 01760, USA.
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12
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Devrim-Lanpir A, Hill L, Knechtle B. Efficacy of Popular Diets Applied by Endurance Athletes on Sports Performance: Beneficial or Detrimental? A Narrative Review. Nutrients 2021; 13:nu13020491. [PMID: 33540813 PMCID: PMC7912997 DOI: 10.3390/nu13020491] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 01/28/2021] [Accepted: 01/29/2021] [Indexed: 12/12/2022] Open
Abstract
Endurance athletes need a regular and well-detailed nutrition program in order to fill their energy stores before training/racing, to provide nutritional support that will allow them to endure the harsh conditions during training/race, and to provide effective recovery after training/racing. Since exercise-related gastrointestinal symptoms can significantly affect performance, they also need to develop strategies to address these issues. All these factors force endurance athletes to constantly seek a better nutritional strategy. Therefore, several new dietary approaches have gained interest among endurance athletes in recent decades. This review provides a current perspective to five popular diet approaches: (a) vegetarian diets, (b) high-fat diets, (c) intermittent fasting diets, (d) gluten-free diet, and (e) low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diets. We reviewed scientific studies published from 1983 to January 2021 investigating the impact of these popular diets on the endurance performance and health aspects of endurance athletes. We also discuss all the beneficial and harmful aspects of these diets, and offer key suggestions for endurance athletes to consider when following these diets.
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Affiliation(s)
- Aslı Devrim-Lanpir
- Department of Nutrition and Dietetics, Faculty of Health Sciences, Istanbul Medeniyet University, 34862 Istanbul, Turkey;
| | - Lee Hill
- Division of Gastroenterology & Nutrition, Department of Pediatrics, McMaster University, Hamilton, ON L8N 3Z5, Canada;
| | - Beat Knechtle
- Medbase St. Gallen, am Vadianplatz, 9001 St. Gallen, Switzerland
- Institute of Primary Care, University of Zurich, 8091 Zurich, Switzerland
- Correspondence: ; Tel.: +41-(0)-71-226-93-00
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13
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Burke LM. Ketogenic low-CHO, high-fat diet: the future of elite endurance sport? J Physiol 2021; 599:819-843. [PMID: 32358802 PMCID: PMC7891323 DOI: 10.1113/jp278928] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 03/27/2020] [Indexed: 01/06/2023] Open
Abstract
The ability of ketogenic low-carbohydrate (CHO) high-fat (K-LCHF) diets to enhance muscle fat oxidation has led to claims that it is the 'future of elite endurance sport'. There is robust evidence that substantial increases in fat oxidation occur, even in elite athletes, within 3-4 weeks and possibly 5-10 days of adherence to a K-LCHF diet. Retooling of the muscle can double exercise fat use to ∼1.5 g min-1 , with the intensity of maximal rates of oxidation shifting from ∼45% to ∼70% of maximal aerobic capacity. Reciprocal reductions in CHO oxidation during exercise are clear, but current evidence to support the hypothesis of the normalization of muscle glycogen content with longer-term adaptation is weak. Importantly, keto-adaptation may impair the muscle's ability to use glycogen for oxidative fates, compromising the use of a more economical energy source when the oxygen supply becomes limiting and, thus, the performance of higher-intensity exercise (>80% maximal aerobic capacity). Even with moderate intensity exercise, individual responsiveness to K-LCHF is varied, with extremes at both ends of the performance spectrum. Periodisation of K-LCHF with high CHO availability might offer opportunities to restore capacity for higher-intensity exercise, but investigations of various models have failed to find a benefit over dietary approaches based on current sports nutrition guidelines. Endurance athletes who are contemplating the use of K-LCHF should undertake an audit of event characteristics and personal experiences to balance the risk of impaired performance of higher-intensity exercise with the likelihood of an unavoidable depletion of carbohydrate stores.
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Affiliation(s)
- Louise M. Burke
- Australian Institute of SportCanberra2616Australia
- Mary MacKillop Institute for Health ResearchAustralian Catholic UniversityMelbourne3000Australia
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14
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Bestard MA, Rothschild JA, Crocker GH. Effect of low- and high-carbohydrate diets on swimming economy: a crossover study. J Int Soc Sports Nutr 2020; 17:64. [PMID: 33298105 PMCID: PMC7724792 DOI: 10.1186/s12970-020-00392-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 11/10/2020] [Indexed: 11/28/2022] Open
Abstract
Background Swimming economy refers to the rate of energy expenditure relative to swimming speed of movement, is inversely related to the energetic cost of swimming, and is as a key factor influencing endurance swimming performance. The objective of this study was to determine if high-carbohydrate, low-fat (HCLF) and low-carbohydrate, high-fat (LCHF) diets affect energetic cost of submaximal swimming. Methods Eight recreational swimmers consumed two 3-day isoenergetic diets in a crossover design. Diets were tailored to individual food preferences, and macronutrient consumption was 69–16-16% and 16–67-18% carbohydrate-fat-protein for the HCLF and LCHF diets, respectively. Following each 3-day dietary intervention, participants swam in a flume at velocities associated with 50, 60, and 70% of their maximal aerobic capacity (VO2max). Expired breath was collected and analyzed while they swam which enabled calculation of the energetic cost of swimming. A paired t-test compared macronutrient distribution between HCLF and LCHF diets, while repeated-measures ANOVA determined effects of diet and exercise intensity on physiological endpoints. Results Respiratory exchange ratio was significantly higher in HCLF compared to LCHF (p = 0.003), but there were no significant differences in the rate of oxygen consumption (p = 0.499) or energetic cost of swimming (p = 0.324) between diets. Heart rate did not differ between diets (p = 0.712), but oxygen pulse, a non-invasive surrogate for stroke volume, was greater following the HCLF diet (p = 0.029). Conclusions A 3-day high-carbohydrate diet increased carbohydrate utilization but did not affect swimming economy at 50–70% VO2max. As these intensities are applicable to ultramarathon swims, future studies should use higher intensities that would be more relevant to shorter duration events.
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Affiliation(s)
- Merry A Bestard
- School of Kinesiology, Nutrition & Food Science, California State University, Los Angeles, 5151 State University Dr, Los Angeles, CA, 90032, USA
| | - Jeffrey A Rothschild
- School of Kinesiology, Nutrition & Food Science, California State University, Los Angeles, 5151 State University Dr, Los Angeles, CA, 90032, USA.,Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand
| | - George H Crocker
- School of Kinesiology, Nutrition & Food Science, California State University, Los Angeles, 5151 State University Dr, Los Angeles, CA, 90032, USA.
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15
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Kysel P, Haluzíková D, Doležalová RP, Laňková I, Lacinová Z, Kasperová BJ, Trnovská J, Hrádková V, Mráz M, Vilikus Z, Haluzík M. The Influence of Cyclical Ketogenic Reduction Diet vs. Nutritionally Balanced Reduction Diet on Body Composition, Strength, and Endurance Performance in Healthy Young Males: A Randomized Controlled Trial. Nutrients 2020; 12:nu12092832. [PMID: 32947920 PMCID: PMC7551961 DOI: 10.3390/nu12092832] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/11/2020] [Accepted: 09/15/2020] [Indexed: 12/14/2022] Open
Abstract
(1) Background: The influence of ketogenic diet on physical fitness remains controversial. We performed a randomized controlled trial to compare the effect of cyclical ketogenic reduction diet (CKD) vs. nutritionally balanced reduction diet (RD) on body composition, muscle strength, and endurance performance. (2) Methods: 25 healthy young males undergoing regular resistance training combined with aerobic training were randomized to CKD (n = 13) or RD (n = 12). Body composition, muscle strength and spiroergometric parameters were measured at baseline and after eight weeks of intervention. (3) Results: Both CKD and RD decreased body weight, body fat, and BMI. Lean body mass and body water decreased in CKD and did not significantly change in RD group. Muscle strength parameters were not affected in CKD while in RD group lat pull-down and leg press values increased. Similarly, endurance performance was not changed in CKD group while in RD group peak workload and peak oxygen uptake increased. (4) Conclusions: Our data show that in healthy young males undergoing resistance and aerobic training comparable weight reduction were achieved by CKD and RD. In RD group; improved muscle strength and endurance performance was noted relative to neutral effect of CKD that also slightly reduced lean body mass.
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Affiliation(s)
- Pavel Kysel
- Department of Sports Medicine, First Faculty of Medicine and General University Hospital, 12000 Prague, Czech Republic; (P.K.); (D.H.); (R.P.D.)
| | - Denisa Haluzíková
- Department of Sports Medicine, First Faculty of Medicine and General University Hospital, 12000 Prague, Czech Republic; (P.K.); (D.H.); (R.P.D.)
| | - Radka Petráková Doležalová
- Department of Sports Medicine, First Faculty of Medicine and General University Hospital, 12000 Prague, Czech Republic; (P.K.); (D.H.); (R.P.D.)
| | - Ivana Laňková
- Centre for Experimental Medicine, Institute for Clinical and Experimental Medicine, 12000 Prague, Czech Republic; (I.L.); (Z.L.); (J.T.)
- Diabetes Centre, Institute for Clinical and Experimental Medicine, 12000 Prague, Czech Republic; (B.J.K.); (V.H.); (M.M.)
| | - Zdeňka Lacinová
- Centre for Experimental Medicine, Institute for Clinical and Experimental Medicine, 12000 Prague, Czech Republic; (I.L.); (Z.L.); (J.T.)
- Institute of Medical Biochemistry and Laboratory Diagnostics, First Faculty of Medicine, Charles University and General University Hospital, 12000 Prague, Czech Republic
| | - Barbora Judita Kasperová
- Diabetes Centre, Institute for Clinical and Experimental Medicine, 12000 Prague, Czech Republic; (B.J.K.); (V.H.); (M.M.)
| | - Jaroslava Trnovská
- Centre for Experimental Medicine, Institute for Clinical and Experimental Medicine, 12000 Prague, Czech Republic; (I.L.); (Z.L.); (J.T.)
| | - Viktorie Hrádková
- Diabetes Centre, Institute for Clinical and Experimental Medicine, 12000 Prague, Czech Republic; (B.J.K.); (V.H.); (M.M.)
| | - Miloš Mráz
- Diabetes Centre, Institute for Clinical and Experimental Medicine, 12000 Prague, Czech Republic; (B.J.K.); (V.H.); (M.M.)
| | - Zdeněk Vilikus
- Department of Sports Medicine, First Faculty of Medicine and General University Hospital, 12000 Prague, Czech Republic; (P.K.); (D.H.); (R.P.D.)
- Correspondence: (Z.V.); (M.H.)
| | - Martin Haluzík
- Diabetes Centre, Institute for Clinical and Experimental Medicine, 12000 Prague, Czech Republic; (B.J.K.); (V.H.); (M.M.)
- Institute of Medical Biochemistry and Laboratory Diagnostics, First Faculty of Medicine, Charles University and General University Hospital, 12000 Prague, Czech Republic
- Correspondence: (Z.V.); (M.H.)
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16
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Murphy NE, Carrigan CT, Margolis LM. High-Fat Ketogenic Diets and Physical Performance: A Systematic Review. Adv Nutr 2020; 12:223-233. [PMID: 32865567 PMCID: PMC7850028 DOI: 10.1093/advances/nmaa101] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 05/13/2020] [Accepted: 07/28/2020] [Indexed: 12/15/2022] Open
Abstract
Use of high-fat, ketogenic diets (KDs) to support physical performance has grown in popularity over recent years. While these diets enhance fat and reduce carbohydrate oxidation during exercise, the impact of a KD on physical performance remains controversial. The objective of this work was to assess the effect of KDs on physical performance compared with mixed macronutrient diets [control (CON)]. A systematic review of the literature was conducted using PubMed and Cochrane Library databases. Randomized and nonrandomized studies were included if participants were healthy (free of chronic disease), nonobese [BMI (kg/m2) <30], trained or untrained men or women consuming KD (<50 g carbohydrate/d or serum or whole-blood β-hydroxybutyrate >0.5 mmol/L) compared with CON (fat, 12-38% of total energy intake) diets for ≥14 d, followed by a physical performance test. Seventeen studies (10 parallel, 7 crossover) with 29 performance (13 endurance, 16 power or strength) outcomes were identified. Of the 13 endurance-type performance outcomes, 3 (1 time trial, 2 time-to-exhaustion) reported lower and 10 (4 time trials, 6 time-to-exhaustion) reported no difference in performance between the KD compared with CON. Of the 16 power or strength performance outcomes, 3 (1 power, 2 strength) reported lower, 11 (4 power, 7 strength) no difference, and 2 (power) enhanced performance in the KD compared with the CON. Risk of bias identified some concern of bias primarily due to studies allowing participants to self-select diet intervention groups and the inability to blind participants to the study intervention. Overall, the majority of null results across studies suggest that a KD does not have a positive or negative impact on physical performance compared with a CON diet. However, discordant results between studies may be due to multiple factors, such as the duration consuming study diets, training status, performance test, and sex differences, which will be discussed in this systematic review.
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Affiliation(s)
- Nancy E Murphy
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA, USA
| | - Christopher T Carrigan
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA, USA
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17
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Changes in body composition and substrate utilization after a short-term ketogenic diet in endurance-trained males. Biol Sport 2020; 38:145-152. [PMID: 33795923 PMCID: PMC7996378 DOI: 10.5114/biolsport.2020.98448] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/19/2020] [Accepted: 07/28/2020] [Indexed: 12/15/2022] Open
Abstract
Few studies have investigated the short-term effects of a very low carbohydrate ketogenic diet (KD) on body composition and substrate utilization in trained individuals. This study investigated effects on substrate utilization during incremental exercise, and changes in body composition, in response to seven days ad libitum consumption of a KD by athletes from endurance sports. Nine young trained males (age, 21.8 ± 1.9 y; height, 1.83 ± 0.11 m; body mass, 78.4 ± 13.8 kg; body fat, 14.9 ± 3.9%; VO2peak, 54.3 ± 5.9 mL kg-1 min-1) were assessed before (day 0; PRE) and after (day 7; POST) seven days of consuming an ad libitum KD. Following an overnight fast, body composition was measured by dual x-ray absorptiometry, and substrate utilization was measured during an incremental (3 min stages, 35 W increments) exercise test on a cycle ergometer. After KD, Wmax (PRE, 295 ± 30 W; POST, 292 ± 38 W) and VO2peak (PRE, 4.18 ± 0.33 L min-1; POST, 4.10 ± 0.43 L min-1) were unchanged, whereas body mass [-2.4 (-3.2, -1.6) kg; P < 0.001, d = 0.21], fat mass [-0.78 (-1.10, -0.46) kg; P < 0.001, d = 0.22] and fat-free mass (FFM) [-1.82 (-3.12, -0.51) kg; P = 0.013, d = 0.22] all decreased. The respiratory exchange ratio was lower, and rates of fat oxidation were higher, at POST across a range of exercise intensities. Maximal fat oxidation rate was ~1.8-fold higher after KD (PRE, 0.54 ± 0.13 g min-1; POST, 0.95 ± 0.24 g min-1; P < 0.001, d = 2.2). Short-term KD results in loss of both fat mass and FFM, increased rates of fat oxidation and a concomitant reduction in CHO utilization even at moderate-to-high intensities of exercise.
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18
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Waldman HS, Heatherly AJ, Killen LG, Hollingsworth A, Koh Y, OʼNeal EK. A 3-Week, Low-Carbohydrate, High-Fat Diet Improves Multiple Serum Inflammatory Markers in Endurance-Trained Males. J Strength Cond Res 2020; 36:2502-2508. [PMID: 32826835 DOI: 10.1519/jsc.0000000000003761] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Waldman, HS, Heatherly, AJ, Killen, LG, Hollingsworth, A, Koh, Y, and O'Neal, EK. A three-week, low-carbohydrate, high-fat diet improves multiple serum inflammatory markers in endurance-trained males. J Strength Cond Res XX(X): 000-000, 2020-This study examined the effects of a low-carbohydrate, high-fat diet (LCHF) on inflammatory marker responses in middle-aged endurance athletes. Eight male runners maintained their habitual mixed diet (HMD) in the first phase of the study before switching to a noncalorically restricted LCHF diet (∼70% of kcals from fat; carbohydrate <50 g) for 3 weeks. Subjects completed a 50-minute fixed pace treadmill running protocol in a hot environment, followed by a 5-km outdoor time trial. Fasting serum samples were collected immediately after exercise and heat stress restriction, and again 24 hours after the exercise/heat stressor. Thirty inflammation markers were assessed using the multiplex flow immunoassay technique. Seven markers (BAFF/TNFSF-13, sCD30/TNFRSF8, sCD163, Chitinase3-like1, gp130SIL-6Rβ, sTNFR-1, and sTNFR-2) reached statistical significance (p < 0.05) favoring LCHF before exercise, and sCD30/TNFRSF8 favored (p < 0.05) LCHF before (HMD = 459 ± 111; LCHF = 296 ± 100) and after (HMD = 385 ± 104; LCHF = 285 ± 104 pg·ml) exercise. Although the current dietary intervention was short in duration, LCHF seems to offer some protection against multiple chronic inflammation markers for physically active men between ages 30 and 50 years.
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Affiliation(s)
- Hunter S Waldman
- Department of Kinesiology, Human Performance Lab, University of North Alabama, Florence, Alabama
| | - Alexander J Heatherly
- Department of Health and Human Performance, Middle Tennessee State University, Murfreesboro, Tennessee
| | - Lauren G Killen
- Department of Kinesiology, Human Performance Lab, University of North Alabama, Florence, Alabama
| | | | - Yunsuk Koh
- Department of Health, Human Performance and Recreation, Baylor University, Waco, Texas
| | - Eric K OʼNeal
- Department of Kinesiology, Human Performance Lab, University of North Alabama, Florence, Alabama
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19
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Kaspar MB, Austin K, Huecker M, Sarav M. Ketogenic Diet: from the Historical Records to Use in Elite Athletes. Curr Nutr Rep 2020; 8:340-346. [PMID: 31713719 DOI: 10.1007/s13668-019-00294-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
PURPOSE OF REVIEW To review the available literature/evidence on low carbohydrate/high fat (LCHF) and low carbohydrate ketogenic (LCKD) diets' effects on human athletic performance and to provide a brief review of the physiology and history of energy systems of exercise. RECENT FINDINGS Multiple studies have been conducted in an attempt to answer this question, many within the last 3-5 years. Studies are heterogenous in design, intervention, and outcome measures. Current available data show that LCHF and LCKD do not significantly enhance or impair performance in endurance or strength activities. However, there is a trend towards improved body composition (greater percent lean body mass) across multiple studies. While this may not translate to enhanced performance in the primarily laboratory conditions in the reviewed studies, there could be a benefit in sports in which an athlete's strength-to-weight ratio is a significant determinant of outcome.
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Affiliation(s)
- Matthew B Kaspar
- Department of Internal Medicine, Division of Gastroenterology, Hepatology, and Nutrition, Virginia Commonwealth University Medical Center, 1200 East Broad Street, P.O. Box 980509, Richmond, VA, 23298, USA.
| | - Kerstin Austin
- Division of Gastroenterology and Hepatology, University of Wisconsin School of Medicine and Public Health, Madison, WI, 53705, USA
| | - Martin Huecker
- Department of Emergency Medicine, University of Louisville School of Medicine, Louisville, KY, USA
| | - Menaka Sarav
- Division of Nephrology and Hypertension, NorthShore University Health System, University of Chicago, Chicago, USA
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20
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Bailey CP, Hennessy E. A review of the ketogenic diet for endurance athletes: performance enhancer or placebo effect? J Int Soc Sports Nutr 2020; 17:33. [PMID: 32571422 PMCID: PMC7310409 DOI: 10.1186/s12970-020-00362-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 06/04/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The ketogenic diet has become popular among endurance athletes as a performance enhancer. This paper systematically reviews the evidence regarding the effect of the endurance athlete's ketogenic diet (EAKD) on maximal oxygen consumption (VO2 max) and secondary performance outcomes. METHODS PubMed and Web of Science searches were conducted through November 2019. Inclusion criteria were documentation of EAKD (< 50 g daily carbohydrate consumed by endurance athletes), ketosis achieved (measured via serum biomarker), VO2 max and/or secondary outcomes, English language, and peer reviewed-publication status. Articles were excluded if they were not a primary source or hypotheses were not tested with endurance athletes (i.e., individuals that compete at submaximal intensity for extended time periods). Study design, diet composition, adherence assessment, serum biomarkers, training protocols, and VO2 max/secondary outcomes were extracted and summarized. RESULTS Searches identified seven articles reporting on VO2 max and/or secondary outcomes; these comprised six intervention trials and one case study. VO2 max outcomes (n = 5 trials, n = 1 case study) were mixed. Two of five trials reported significant increases in VO2 max across all diets; while three trials and one case study reported no significant VO2 max findings. Secondary outcomes (n = 5 trials, n = 1 case study) were Time to Exhaustion (TTE; n = 3 articles), Race Time (n = 3 articles), Rating of Perceived Exertion (RPE; n = 3 articles), and Peak Power (n = 2 articles). Of these, significant findings for EAKD athletes included decreased TTE (n = 1 article), higher RPE (n = 1 article), and increased Peak Power (n = 1 article). CONCLUSION Limited and heterogeneous findings prohibit definitive conclusions regarding efficacy of the EAKD for performance benefit. When compared to a high carbohydrate diet, there are mixed findings for the effect of EAKD consumption on VO2 max and other performance outcomes. More randomized trials are needed to better understand the potentially nuanced effects of EAKD consumption on endurance performance. Researchers may also consider exploring the impact of genetics, recovery, sport type, and sex in moderating the influence of EAKD consumption on performance outcomes.
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Affiliation(s)
- Caitlin P Bailey
- The Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy at Tufts University, 150 Harrison Avenue, Boston, MA, 02111, USA.
| | - Erin Hennessy
- The Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy at Tufts University, 150 Harrison Avenue, Boston, MA, 02111, USA
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21
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Maffetone P, Laursen PB. Maximum Aerobic Function: Clinical Relevance, Physiological Underpinnings, and Practical Application. Front Physiol 2020; 11:296. [PMID: 32300310 PMCID: PMC7142223 DOI: 10.3389/fphys.2020.00296] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 03/16/2020] [Indexed: 11/13/2022] Open
Abstract
The earliest humans relied on large quantities of metabolic energy from the oxidation of fatty acids to develop larger brains and bodies, prevent and reduce disease risk, extend longevity, in addition to other benefits. This was enabled through the consumption of a high fat and low-carbohydrate diet (LCD). Increased fat oxidation also supported daily bouts of prolonged, low-intensity, aerobic-based physical activity. Over the past 40-plus years, a clinical program has been developed to help people manage their lifestyles to promote increased fat oxidation as a means to improve various aspects of health and fitness that include reducing excess body fat, preventing disease, and optimizing human performance. This program is referred to as maximum aerobic function, and includes the practical application of a personalized exercise heart rate (HR) formula of low-to-moderate intensity associated with maximal fat oxidation (MFO), and without the need for laboratory evaluations. The relationship between exercise training at this HR and associated laboratory measures of MFO, health outcomes and athletic performance must be verified scientifically.
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Affiliation(s)
- Philip Maffetone
- Independent Researcher, Ormond Beach, FL, United States.,Auckland University of Technology, Auckland, New Zealand
| | - Paul B Laursen
- Auckland University of Technology, Auckland, New Zealand
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22
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Waldman HS, Smith JW, Lamberth J, Fountain BJ, McAllister MJ. A 28-Day Carbohydrate-Restricted Diet Improves Markers of Cardiometabolic Health and Performance in Professional Firefighters. J Strength Cond Res 2020; 33:3284-3294. [PMID: 31469768 DOI: 10.1519/jsc.0000000000003354] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Waldman, HS, Smith, JW, Lamberth, J, Fountain, BJ, and McAllister, MJ. A 28-day carbohydrate-restricted diet improves markers of cardiometabolic health and performance in professional firefighters. J Strength Cond Res 33(12): 3284-3294, 2019-We investigated the effects of a 4-week ad-libitum, nonketogenic, carbohydrate-restricted (<25% of calories) diet (CRD) on cardiometabolic and performance markers in firefighters (FF). Subjects (n = 15) completed 9 sessions (trials 1-3 [familiarization], trials 4-6 [baseline], and trials 7-9 [post-CRD]). Following habitual western diet, anthropometric measures were assessed, glucose tolerance measured, and then completed a graded cycling test, maximal Wingate test, and conducted their FF physical performance assessment (FPPA) to measure performance while metabolic variables and perceptual responses were recorded. Subjects then adhered to a CRD for a 4-week duration and returned for repeat testing. Body fat as measured by BodPod, and 7-site skinfold thickness decreased (p < 0.01), and a decrease was observed in blood pressure (BP) (p < 0.01; ∼5 mm Hg) after CRD. There were no differences found for glucose tolerance, but an increase was found for fat oxidation rates (p < 0.01; ∼0.07 g·min) and a decrease in carbohydrate oxidation rates across a range of intensities (p < 0.01; ∼0.24 g·min). Finally, the 2.41-km run and pull-up performance during the FPPA improved (p < 0.01; ∼41 second and 3 repetitions, respectively) and with no differences observed between treatments regarding the Wingate test. To date, this is the first CRD implemented with FF and resulted in decreased fat mass (∼2.4 kg), BP, and improvements to performance on the FPPA while preserving high-intensity exercise. These data suggest that a 28-day CRD can benefit markers of health in professional FF without detriments to occupational performance.
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Affiliation(s)
- Hunter S Waldman
- Human Performance Lab, Department of Kinesiology, University of North Alabama, Florence, Alabama.,Applied Physiology Lab, Department of Kinesiology, Mississippi State University, Starkville, Mississippi
| | - JohnEric W Smith
- Applied Physiology Lab, Department of Kinesiology, Mississippi State University, Starkville, Mississippi
| | - John Lamberth
- Applied Physiology Lab, Department of Kinesiology, Mississippi State University, Starkville, Mississippi
| | - Brent J Fountain
- Department of Food Science, Nutrition, and Health Promotion, Mississippi State University, Starkville, Mississippi
| | - Matthew J McAllister
- Metabolic and Applied Physiology Lab, Department of Health and Human Performance, Texas State University, San Marcos, Texas
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23
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Kang J, Ratamess NA, Faigenbaum AD, Bush JA. Ergogenic Properties of Ketogenic Diets in Normal-Weight Individuals: A Systematic Review. J Am Coll Nutr 2020; 39:665-675. [PMID: 32039654 DOI: 10.1080/07315724.2020.1725686] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Ketogenic diets (KDs) have received increasing attention among athletes and physically active individuals. However, the question as to whether and how the diet could benefit this healthy cohort remains unclear.Purpose: This study was designed to systematically review the existing evidence concerning the effect of KDs on body composition, aerobic and anaerobic capacity, muscle development, and sports performance in normal-weight individuals including athletes.Methods: A systematic search of English literature was conducted through electronic databases including PubMed, EBSCOhost, and Google Scholar. Upon the use of search criteria, 23 full-text original human studies involving non-obese participants were included in this review. For more stratified and focused analysis, these articles were further categorized based on the outcomes being examined including 1) body mass (BM) and %fat, 2) substrate utilization, 3) blood substrate and hormonal responses, 4) aerobic capacity and endurance performance, and 5) strength, power, and anaerobic capacity.Results: Our review indicates that a non-calorie-restricted KD carried out for ≥3 weeks can produce a modest reduction in BM and %fat, while maintaining fat-free mass. This diet leads to augmented use of fat as fuel, but this adaptation doesn't seem to improve endurance performance. Additionally, ad libitum KDs combined with resistance training will pose no harm to developing strength and power, especially when protein intake is increased modestly.Conclusions: It appears that a non-calorie-restricted KD provides minimal ergogenic benefits in normal-weight individuals including athletes, but can be used for optimizing BM and body composition without compromising aerobic and anaerobic performance. Key teaching pointsKetogenic diets have received increasing attention among athletes and physically active individuals.It remains elusive as to whether ketogenic diets could confer ergogenic benefits for those who are normal weight but want to use the diet to improve fitness and performance.An interesting dilemma exists in that ketogenic diets can reduce body mass and %fat and increase fat oxidation, but they can also decrease glycogen stores and limit sports performance.This review concludes that a non-calorie-restricted ketogenic diet provides minimal ergogenic benefits in normal-weight individuals, but can be used to optimize body mass and composition without compromising athletic performance.This finding can be important for esthetic or weight-sensitive athletes because the diet may allow them to reach a target body mass without having to sacrifice athletic performance.The ketogenic diet-induced metabolic adaptations require a state of ketosis, and thus caution should be taken because an excessive increase in ketone bodies can be detrimental to health.
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Affiliation(s)
- Jie Kang
- Human Performance Laboratory, The College of New Jersey, Ewing, New Jersey, USA
| | - Nicholas A Ratamess
- Human Performance Laboratory, The College of New Jersey, Ewing, New Jersey, USA
| | - Avery D Faigenbaum
- Human Performance Laboratory, The College of New Jersey, Ewing, New Jersey, USA
| | - Jill A Bush
- Human Performance Laboratory, The College of New Jersey, Ewing, New Jersey, USA
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McSwiney FT, Doyle L, Plews DJ, Zinn C. Impact Of Ketogenic Diet On Athletes: Current Insights. Open Access J Sports Med 2019; 10:171-183. [PMID: 31814784 PMCID: PMC6863116 DOI: 10.2147/oajsm.s180409] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 10/04/2019] [Indexed: 02/05/2023] Open
Abstract
The impact of a ketogenic diet (KD) (<50 g/d carbohydrate, >75% fat) on athletic performance has sparked much interest and self-experimentation in the past 3-4 years. Evidence shows 3-4-week adaptations to a KD in endurance-trained athletes were associated with maintenance of moderate (46-63% VO2max) and vigorous intensity (64-90% VO2max) endurance exercise, while at intensities >70% VO2max, increases in fat oxidation were associated with decreased economy (increased oxygen consumption), and in some cases, increased ratings of perceived exertion and heart rate. Two investigations in recreationally active endurance athletes noted no vigorous intensity exercise decrement following 3- and 12-week adaptations. Moderate (70-85% one repetition maximum) and near-maximal to maximal intensity (>85% 1RM) strength performance experienced no decrement following a 3-12-week KD adaptation. Beneficial effects were noted for 2000 m sprint and critical power test completed for short duration at vigorous intensity, while two additional tests noted no decrement. For sprint, near-maximal exercise (>91% VO2max), benefit of the KD was observed for six-second sprint, while no decrement in performance was noted for two additional maximal tests. When protein is equated (grams per kilogram), one investigation noted no decrement in muscle hypertrophy, while one noted a decrement. One investigation with matched protein noted the KD group lost more body fat. In conclusion, moderate-to-vigorous intensity exercise experiences no decrement following adaptation to a KD. Decreases in exercise economy are observed >70% VO2max in trained endurance athletes which may negate performance within field settings. Beneficial effects of the KD during short duration vigorous, and sprint bouts of exercises are often confounded by greater weight loss in the KD group. With more athletes pursuing carbohydrate-restricted diets (moderate and strict (KD)) for their proposed health benefits, more work is needed in the area to address both performance and health outcomes.
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Affiliation(s)
- Fionn T McSwiney
- School of Health and Human Performance, Dublin City University, Dublin, Ireland.,Setanta College, Thurlus, Tipperary, Ireland
| | - Lorna Doyle
- Department of Sport and Exercise Science, Waterford Institute of Technology, Waterford, Ireland
| | - Daniel J Plews
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand
| | - Caryn Zinn
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand
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Dostal T, Plews DJ, Hofmann P, Laursen PB, Cipryan L. Effects of a 12-Week Very-Low Carbohydrate High-Fat Diet on Maximal Aerobic Capacity, High-Intensity Intermittent Exercise, and Cardiac Autonomic Regulation: Non-randomized Parallel-Group Study. Front Physiol 2019; 10:912. [PMID: 31379612 PMCID: PMC6652046 DOI: 10.3389/fphys.2019.00912] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 07/03/2019] [Indexed: 11/13/2022] Open
Abstract
Purpose The aim of this non-randomized parallel group study was to examine the 12 week effects of a very low-carbohydrate high-fat diet (VLCHF) on maximal cardiorespiratory capacity, high-intensity interval training (HIIT) performance, and cardiac autonomic regulation. Methods Twenty-four recreationally trained participants allocated to either a VLCHF (N = 12) or a habitual diet (HD; N = 12) group completed 12 weeks of a diet and exercise (VLCHF) or an exercise only intervention (HD). Maximal graded exercise tests (GXT) were performed at baseline, after 4, 8, and 12 weeks. A supervised HIIT session and the 30-15 Intermittent Fitness Test (30-15IFT) were conducted once a week. Results Total time to exhaustion (TTE) in both GXT and 30-15IFTlargely increased in both VLCHF (p = 0.005, BF10 = 11.30 and p = 0.001, BF10 ≥ 100, respectively) and HD (p = 0.018, BF10 = 3.87 and p = 0.001, BF10 ≥ 100, respectively) groups after 12 weeks. Absolute maximal oxygen uptake (V˙O2max) was not changed in both groups but relative V˙O2max increased in VLCHF in concert with reductions in body mass (66.7 ± 10.2–63.1 ± 8.5 kg). Cardiac autonomic regulation did not reveal any between-group differences after 12 weeks. VLCHF diet induced an increase in β-hydroxybutyrate, which tended to normalize during the intervention period. Conclusion The 12 week VLCHF diet did not impair high-intensity continuous or intermittent exercise lasting up to 25 min, nor did it impair maximal cardiorespiratory performance or autonomic nervous system (ANS) activity.
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Affiliation(s)
- Tomas Dostal
- Department of Human Movement Studies, Human Motion Diagnostic Centre, University of Ostrava, Ostrava, Czechia
| | - Daniel J Plews
- Sport Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand
| | - Peter Hofmann
- Exercise Physiology, Training and Training Therapy Research Group, Institute of Sports Science, University of Graz, Graz, Austria
| | - Paul B Laursen
- Sport Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand
| | - Lukas Cipryan
- Department of Human Movement Studies, Human Motion Diagnostic Centre, University of Ostrava, Ostrava, Czechia
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26
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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; 16:16. [PMID: 30953522 PMCID: PMC6451242 DOI: 10.1186/s12970-019-0284-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 03/26/2019] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND The ketogenic diet is becoming a popular nutritional model among athletes. However, the relationship between its use and metabolism during exercise seems to have not been fully investigated. METHODS The aim of the study was to assess the effects of a four-week ketogenic diet (KD) on fat and carbohydrate (CHO) utilization during an incremental cycling test (ICT) in CrossFit-trained female (n = 11) and male (n = 11) athletes. During the ICT (while consuming the customary diet and after the KD), oxygen uptake and carbon dioxide exhalation were registered, and CHO and fat utilization as well as energy expenditure were calculated. RESULTS In males, the KD led to an increase in fat utilization (g·min- 1·kgFFM- 1 and % oxidation). It was particularly noticeable at exercise intensities up to 80% of VO2max. An increase in the area under the curve (AUC) was seen in males but not in females at up to ≤65% VO2max of fat utilization. CONCLUSIONS Male CrossFit-trained athletes seem to be more prone to shifts in macronutrient utilization (in favor of fat utilization) during submaximal intensity exercise under a ketogenic diet than are female athletes. TRIAL REGISTRATION Clinical Trials Gov, NCT03665948 . Registered 11 September 2018 (retrospectively registered).
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Affiliation(s)
- Krzysztof Durkalec-Michalski
- Institute of Human Nutrition and Dietetics, Poznan University of Life Sciences, Wojska Polskiego 31, 60-624 Poznań, Poland
- Department of Food and Nutrition, Poznan University of Physical Education, 61-871 Poznań, Poland
| | - Paulina M. Nowaczyk
- Institute of Human Nutrition and Dietetics, Poznan University of Life Sciences, Wojska Polskiego 31, 60-624 Poznań, Poland
| | - Katarzyna Siedzik
- Institute of Human Nutrition and Dietetics, Poznan University of Life Sciences, Wojska Polskiego 31, 60-624 Poznań, Poland
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27
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Tanji F, Nabekura Y. Oxygen uptake and respiratory exchange ratio relative to the lactate threshold running in well-trained distance runners. J Sports Med Phys Fitness 2019; 59:895-901. [PMID: 30893995 DOI: 10.23736/s0022-4707.18.08828-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND This study compared oxygen uptake (V̇O2) and the respiratory exchange ratio (RER) between well-trained distance runners (DRs) and recreational runners (RRs) below, at, and above the lactate threshold (LT) during a four-minute run and clarified whether these variables reached steady state in DRs. METHODS Ten male well-trained DRs (maximal oxygen uptake [V̇O2max], 66.8±5.9 mL/kg/min; LT, 80.0±4.4% V̇O2max) and nine male RRs (V̇O2max, 53.9±3.7 mL/kg/min; LT, 76.6±8.0% V̇O2max) participated in this study. They performed four-minute runs at 70%, 80%, and 90% V̇O2max on a treadmill. RESULTS The results illustrated that V̇O2 was higher in the fourth minute than in the third minute in RRs at 80% and 90% V̇O2max (Cohen's d=0.25 and 0.26, respectively), whereas, V̇O2 did not differ between the third and fourth minute in DRs at any intensity (Cohen's d=0.08, 0.03, and 0.04, respectively). The RER at each intensity differed between the third and fourth minutes in RRs (Cohen's d=0.25, 0.21, and 0.41, respectively); similarly, RER was only different between the third and fourth minutes at 90%V̇O2max (Cohen's d=0.39) in DRs. CONCLUSIONS These results indicate that the slow component of V̇O2 is not observed in runners with good aerobic capacity even at running intensity exceeding the LT, whereas the RER does not reach steady state at this intensity.
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Affiliation(s)
- Fumiya Tanji
- Department of Sport Research, Japan Institute of Sport Sciences, Tokyo, Japan - .,Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan -
| | - Yoshiharu Nabekura
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
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Song G, Wang Y, Chen X, Pang S, Miao H, Li A, Wang W. Influences of ratio of macro-nutrients intake to human and animals: an overview. FOOD AGR IMMUNOL 2019. [DOI: 10.1080/09540105.2018.1561832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Affiliation(s)
- Ge Song
- Academy of State Administration of Grain, Beijing, People’s Republic of China
| | - Yong Wang
- Academy of State Administration of Grain, Beijing, People’s Republic of China
| | - Xi Chen
- Academy of State Administration of Grain, Beijing, People’s Republic of China
| | - Shaojie Pang
- Academy of State Administration of Grain, Beijing, People’s Republic of China
| | - Haijiang Miao
- Academy of State Administration of Grain, Beijing, People’s Republic of China
| | - Aike Li
- Academy of State Administration of Grain, Beijing, People’s Republic of China
| | - Weiwei Wang
- Academy of State Administration of Grain, Beijing, People’s Republic of China
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Rothschild J, Earnest CP. Dietary Manipulations Concurrent to Endurance Training. J Funct Morphol Kinesiol 2018; 3:jfmk3030041. [PMID: 33466970 PMCID: PMC7739303 DOI: 10.3390/jfmk3030041] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 07/11/2018] [Accepted: 07/23/2018] [Indexed: 12/20/2022] Open
Abstract
The role of an athlete's dietary intake (both timing and food type) goes beyond simply providing fuel to support the body's vital processes. Nutritional choices also have an impact on the metabolic adaptations to training. Over the past 20 years, research has suggested that strategically reducing carbohydrate (CHO) availability during an athlete's training can modify the metabolic responses in lieu of simply maintaining a high CHO diet. Several methods have been explored to manipulate CHO availability and include: Low-carb, high-fat (LCHF) diets, performing two-a-day training without glycogen restoration between sessions, and a "sleep-low" approach entailing a glycogen-depleting session in the evening without consuming CHO until after a morning training session performed in an overnight fasted state. Each of these methods can confer beneficial metabolic adaptations for the endurance athlete including increases in mitochondrial enzyme activity, mitochondrial content, and rates of fat oxidation, yet data showing a direct performance benefit is still unclear.
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Affiliation(s)
| | - Conrad P. Earnest
- Exercise and Sport Nutrition Laboratory, Texas A&M University, College Station, TX 77843, USA
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