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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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Graybeal AJ, Kreutzer A, Moss K, Shah M. Changes in the chronic and postprandial blood lipid profiles of trained competitive cyclists and triathletes following a ketogenic diet: a randomized crossover trial. BMC Sports Sci Med Rehabil 2024; 16:19. [PMID: 38229197 PMCID: PMC10790427 DOI: 10.1186/s13102-023-00801-5] [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: 10/27/2023] [Accepted: 12/25/2023] [Indexed: 01/18/2024]
Abstract
BACKGROUND The ketogenic diet (KD) is the most popular carbohydrate restriction strategy for endurance athletes. However, because the primary goal of employing the KD is to gain a competitive advantage in competition, endurance athletes may be less concerned with the influence of the KD on their cardiometabolic health; particularly their blood lipid profiles. Thus, the purpose of this study was to examine the chronic and postprandial blood lipid alterations following a two-week ad libitum KD compared to an ad libitum high-carbohydrate diet (HCD) and the athletes' habitual diet (HD) in a group of trained competitive cyclists and triathletes. METHODS Six trained competitive cyclists and triathletes (female: 4, male: 2; age: 37.2 ± 12.2) completed this randomized crossover trial, which required them to follow a two-week ad libitum KD and HCD in a randomized order after their HD. Fasting blood lipids were collected following their HD and after two-weeks of the KD and HCD conditions. Postprandial blood lipid responses to a test meal reflective of the assigned diet were collected at the end of each diet condition. RESULTS Fasting total cholesterol (TC) was significantly higher following the KD compared to the HD (p < 0.001) and HCD (p = 0.006). Postprandial incremental area under the curve for triglycerides (TRG), TRG:HDL ratio, and VLDL-C were significantly higher following the KD test meal compared to the HD (all p < 0.001) and HCD (all p = 0.001) test meals but LDL-C and LDL:HDL ratio were significantly lower following the KD compared to the HD and HCD test meals (all p < 0.001). CONCLUSIONS Trained competitive cyclists and triathletes demonstrate increased TC in response to a two-week KD compared to a HCD or HD. Endurance athletes contemplating a KD should consider the potential for these blood lipid alterations, and future research should focus on postprandial blood lipid responses to determine if these changes manifest in chronic blood lipid shifts. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT04097171 (11 October 2019).
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Affiliation(s)
- Austin J Graybeal
- School of Kinesiology & Nutrition, College of Education and Human Sciences, University of Southern Mississippi, 39406, Hattiesburg, MS, USA.
| | - Andreas Kreutzer
- Department of Research Data Science & Analytics, Cook Children's Health Care System, 76104, Fort Worth, TX, USA
| | - Kamiah Moss
- Physical Medicine and Rehabilitation, Baylor Institute for Rehabilitation, 75246, Dallas, TX, USA
| | - Meena Shah
- Department of Kinesiology, Harris College of Nursing and Health Sciences, Texas Christian University, 76129, Fort Worth, TX, USA.
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Graybeal AJ, Kreutzer A, Moss K, Rack P, Augsburger G, Braun-Trocchio R, Willis JL, Shah M. Chronic and Postprandial Metabolic Responses to a Ketogenic Diet Compared to High-Carbohydrate and Habitual Diets in Trained Competitive Cyclists and Triathletes: A Randomized Crossover Trial. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:1110. [PMID: 36673864 PMCID: PMC9859046 DOI: 10.3390/ijerph20021110] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 01/05/2023] [Accepted: 01/06/2023] [Indexed: 06/17/2023]
Abstract
Extreme carbohydrate deficits during a ketogenic diet (KD) may result in metabolic adaptations reflective of low energy availability; however, the manifestation of these adaptations outside of exercise have yet to be elucidated in cyclists and triathletes. The purpose of this study is to investigate the chronic and postprandial metabolic responses to a KD compared to a high-carbohydrate diet (HCD) and habitual diet (HD) in trained competitive cyclists and triathletes. For this randomized crossover trial, six trained competitive cyclist and triathletes (F: 4, M: 2) followed an ad libitum KD and HCD for 14 d each after their HD. Fasting energy expenditure (EE), respiratory exchange ratio (RER), and fat and carbohydrate oxidation (FatOx and CarbOx, respectively) were collected during their HD and after 14 d on each randomly assigned KD and HCD. Postprandial measurements were collected on day 14 of each diet following the ingestion of a corresponding test meal. There were no significant differences in fasting EE, RER, FatOx, or CarbOx among diet conditions (all p > 0.050). Although postprandial RER and CarbOx were consistently lower following the KD meal, there were no differences in peak postprandial RER (p = 0.452), RER incremental area under the curve (iAUC; p = 0.416) postprandial FatOx (p = 0.122), peak FatOx (p = 0.381), or FatOx iAUC (p = 0.164) between the KD and HD meals. An ad libitum KD does not significantly alter chronic EE or substrate utilization compared to a HCD or HD; postprandial FatOx appears similar between a KD and HD; this is potentially due to the high metabolic flexibility of cyclists and triathletes and the metabolic adaptations made to habitual high-fat Western diets in practice. Cyclists and triathletes should consider these metabolic similarities prior to a KD given the potential health and performance impairments from severe carbohydrate restriction.
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Affiliation(s)
- Austin J. Graybeal
- School of Kinesiology & Nutrition, College of Education and Human Sciences, University of Southern Mississippi, Hattiesburg, MS 39406, USA
| | - Andreas Kreutzer
- Department of Kinesiology, Harris College of Nursing and Health Sciences, Texas Christian University, Fort Worth, TX 76129, USA
- School of Health Promotion and Kinesiology, College of Health Sciences, Texas Woman’s University, Denton, TX 76209, USA
| | - Kamiah Moss
- Department of Kinesiology, Harris College of Nursing and Health Sciences, Texas Christian University, Fort Worth, TX 76129, USA
- Physical Medicine and Rehabilitation, Baylor Institute for Rehabilitation, Dallas, TX 75246, USA
| | - Petra Rack
- Department of Kinesiology, Harris College of Nursing and Health Sciences, Texas Christian University, Fort Worth, TX 76129, USA
| | - Garrett Augsburger
- Department of Kinesiology, Harris College of Nursing and Health Sciences, Texas Christian University, Fort Worth, TX 76129, USA
| | - Robyn Braun-Trocchio
- Department of Kinesiology, Harris College of Nursing and Health Sciences, Texas Christian University, Fort Worth, TX 76129, USA
| | - Jada L. Willis
- Department of Nutritional Sciences, College of Science & Engineering, Texas Christian University, Fort Worth, TX 76129, USA
| | - Meena Shah
- Department of Kinesiology, Harris College of Nursing and Health Sciences, Texas Christian University, Fort Worth, TX 76129, USA
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Graybeal AJ, Kreutzer A, Willis JL, Braun-Trocchio R, Moss K, Shah M. The impact of dieting culture is different between sexes in endurance athletes: a cross-sectional analysis. BMC Sports Sci Med Rehabil 2022; 14:157. [PMID: 35978366 PMCID: PMC9382595 DOI: 10.1186/s13102-022-00549-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 07/28/2022] [Indexed: 11/13/2022]
Abstract
Background Frequent dieting is common in athletes attempting to achieve a body composition perceived to improve performance. Excessive dieting may indicate disordered eating (DE) behaviors and can result in clinical eating disorders. However, the current nutrition patterns that underly dieting culture are underexplored in endurance athletes. Therefore, the purpose of this study was to identify the sex differences in nutrition patterns among a group of endurance athletes. Methods Two-hundred and thirty-one endurance athletes (females = 124) completed a questionnaire regarding their dieting patterns and associated variables. Results The majority of athletes did not follow a planned diet (70.1%). For endurance athletes on planned diets (n = 69), males were more likely follow a balanced diet (p = 0.048) and females were more likely to follow a plant-based diet (p = 0.021). Female endurance athletes not on a planned diet (n = 162) were more likely to have attempted at least one diet (p < 0.001). Male athletes attempted 2.0 ± 1.3 different diets on average compared to 3.0 ± 2.0 for females (p = 0.002). Female athletes were more likely to attempt ≥ three diets (p = 0.022). The most common diet attempts included carbohydrate/energy restrictive, plant-based, and elimination diets. Females were more likely to attempt ketogenic (p = 0.047), low-carbohydrate (p = 0.002), and energy restricted diets (p = 0.010). Females made up the entirety of those who attempted gluten-/dairy-free diets (F = 22.0%, M = 0.0%). Conclusions Being a female athlete is a major determinant of higher dieting frequency and continual implementation of popular restrictive dietary interventions. Sports dietitians and coaches should prospectively assess eating behavior and provide appropriate programming, education, and monitoring of female endurance athletes.
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Affiliation(s)
- Austin J Graybeal
- School of Kinesiology & Nutrition, College of Education and Human Sciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA.
| | - Andreas Kreutzer
- Department of Kinesiology, Harris College of Nursing & Health Sciences, Texas Christian University, Fort Worth, TX, 76129, USA
| | - Jada L Willis
- Department of Nutritional Sciences, College of Science & Engineering, Texas Christian University, Fort Worth, TX, 76129, USA
| | - Robyn Braun-Trocchio
- Department of Kinesiology, Harris College of Nursing & Health Sciences, Texas Christian University, Fort Worth, TX, 76129, USA
| | - Kamiah Moss
- Department of Kinesiology, Harris College of Nursing & Health Sciences, Texas Christian University, Fort Worth, TX, 76129, USA
| | - Meena Shah
- Department of Kinesiology, Harris College of Nursing & Health Sciences, Texas Christian University, Fort Worth, TX, 76129, USA
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