1
|
Prieto-Bellver G, Diaz-Lara J, Bishop DJ, Fernández-Sáez J, Abián-Vicén J, San-Millan I, Santos-Concejero J. A Five-Week Periodized Carbohydrate Diet Does Not Improve Maximal Lactate Steady-State Exercise Capacity and Substrate Oxidation in Well-Trained Cyclists compared to a High-Carbohydrate Diet. Nutrients 2024; 16:318. [PMID: 38276556 PMCID: PMC10820927 DOI: 10.3390/nu16020318] [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: 12/30/2023] [Revised: 01/15/2024] [Accepted: 01/19/2024] [Indexed: 01/27/2024] Open
Abstract
There is a growing interest in studies involving carbohydrate (CHO) manipulation and subsequent adaptations to endurance training. This study aimed to analyze whether a periodized carbohydrate feeding strategy based on a daily training session has any advantages compared to a high-carbohydrate diet in well-trained cyclists. Seventeen trained cyclists (VO2peak = 70.8 ± 6.5 mL·kg-1·min-1) were divided into two groups, a periodized (PCHO) group and a high-carbohydrate (HCHO) group. Both groups performed the same training sessions for five weeks. In the PCHO group, 13 training sessions were performed with low carbohydrate availability. In the HCHO group, all sessions were completed following previous carbohydrate intake to ensure high pre-exercise glycogen levels. In both groups, there was an increase in the maximal lactate steady state (MLSS) (PCHO: 244.1 ± 29.9 W to 253.2 ± 28.4 W; p = 0.008; HCHO: 235.8 ± 21.4 W to 246.9 ± 16.7 W; p = 0.012) but not in the time to exhaustion at MLSS intensity. Both groups increased the percentage of muscle mass (PCHO: p = 0.021; HCHO: p = 0.042) and decreased the percent body fat (PCHO: p = 0.021; HCHO: p = 0.012). We found no differences in carbohydrate or lipid oxidation, heart rate, and post-exercise lactate concentration. Periodizing the CHO intake in well-trained cyclists during a 5-week intervention did not elicit superior results to an energy intake-matched high-carbohydrate diet in any of the measured outcomes.
Collapse
Affiliation(s)
- Gorka Prieto-Bellver
- Performance and Sport Rehabilitation Laboratory, Faculty of Sport Sciences, University of Castilla-La Mancha, 45071 Toledo, Spain; (G.P.-B.); (J.A.-V.)
| | - Javier Diaz-Lara
- Performance and Sport Rehabilitation Laboratory, Faculty of Sport Sciences, University of Castilla-La Mancha, 45071 Toledo, Spain; (G.P.-B.); (J.A.-V.)
| | - David J. Bishop
- Institute for Health and Sport (IHeS), Victoria University, Footscray VIC 3011, Australia;
| | - José Fernández-Sáez
- Unitat de Suport a la Recerca Terres de l’Ebre, Fundació Institut Universitari per a la Recerca a l’Atenció Primària de Salut Jordi Gol i Gurina (IDIAPJGol), 43500 Tortosa, Spain;
| | - Javier Abián-Vicén
- Performance and Sport Rehabilitation Laboratory, Faculty of Sport Sciences, University of Castilla-La Mancha, 45071 Toledo, Spain; (G.P.-B.); (J.A.-V.)
| | - Iñigo San-Millan
- Department of Human Physiology and Nutrition, University of Colorado, Colorado Springs, CO 80918, USA;
| | - Jordan Santos-Concejero
- Department of Physical Education and Sport, University of the Basque Country UPV/EHU, 48940 Leioa, Spain;
| |
Collapse
|
2
|
Melin AK, Areta JL, Heikura IA, Stellingwerff T, Torstveit MK, Hackney AC. Direct and indirect impact of low energy availability on sports performance. Scand J Med Sci Sports 2024; 34:e14327. [PMID: 36894187 DOI: 10.1111/sms.14327] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/27/2023] [Accepted: 02/01/2023] [Indexed: 03/11/2023]
Abstract
Low energy availability (LEA) occurs inadvertently and purposefully in many athletes across numerous sports; and well planned, supervised periods with moderate LEA can improve body composition and power to weight ratio possibly enhancing performance in some sports. LEA however has the potential to have negative effects on a multitude of physiological and psychological systems in female and male athletes. Systems such as the endocrine, cardiovascular, metabolism, reproductive, immune, mental perception, and motivation as well as behaviors can all be impacted by severe (serious and/or prolonged or chronic) LEA. Such widely diverse effects can influence the health status, training adaptation, and performance outcomes of athletes leading to both direct changes (e.g., decreased strength and endurance) as well as indirect changes (e.g., reduced training response, increased risk of injury) in performance. To date, performance implications have not been well examined relative to LEA. Therefore, the intent of this narrative review is to characterize the effects of short-, medium-, and long-term exposure to LEA on direct and indirect sports performance outcomes. In doing so we have focused both on laboratory settings as well as descriptive athletic case-study-type experiential evidence.
Collapse
Affiliation(s)
- Anna K Melin
- Department of Sport Science, Faculty of Social Sciences, Swedish Olympic Committee Research Fellow, Linnaeus University, Växjö/Kalmar, Sweden
| | - José L Areta
- School of Sport and Exercise Sciences, Faculty of Science, Liverpool John Moores University, Liverpool, UK
| | - Ida A Heikura
- Canadian Sport Institute - Pacific, Victoria, British Columbia, Canada
- Exercise Science, Physical & Health Education, University of Victoria, Victoria, British Columbia, Canada
| | - Trent Stellingwerff
- Canadian Sport Institute - Pacific, Victoria, British Columbia, Canada
- Exercise Science, Physical & Health Education, University of Victoria, Victoria, British Columbia, Canada
| | - Monica Klungland Torstveit
- Department of Sport Science and Physical Education, Faculty of Health and Sport Science, University of Agder, Kristiansand, Norway
| | - Anthony C Hackney
- Department of Exercise & Sport Science, University of North Carolina, Chapel Hill, North Carolina, USA
| |
Collapse
|
3
|
Kazemi A, Racil G, Ahmadi Hekmatikar AH, Behnam Moghadam M, Karami P, Henselmans M. Improved physical performance of elite soccer players based on GPS results after 4 days of carbohydrate loading followed by 3 days of low carbohydrate diet. J Int Soc Sports Nutr 2023; 20:2258837. [PMID: 37731274 PMCID: PMC10515665 DOI: 10.1080/15502783.2023.2258837] [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: 04/04/2023] [Accepted: 09/07/2023] [Indexed: 09/22/2023] Open
Abstract
BACKGROUND Carbohydrate loading is an established sports nutrition strategy for endur- 16 ance exercise performance. We tested if carbohydrate loading could improve the performance of 17 elite soccer players under ecologically valid circumstances using Global Positioning System (GPS) data. METHODS Twenty-two adult Iran Premier league soccer players were divided into a carbohydrate-loading group (CLG) and Control group (CG). The carbohydrate loading group restricted carbohydrate intake for three days to 1.5 g/kg/d while increasing exercise intensity. From days four to seven, exercise intensity was decreased and carbohydrate intake was considerably increased up to 7.5 g/kg/d on the day of the match, during which performance was analyzed using GPS data. The control group performed the same exercise training but maintained their habitual carbohydrate intake of 5-6 g/kg/d. The data were analyzed using a univariate ANCOVA with baseline data from a pre-intervention match as the control variable. RESULTS The carbohydrate loading team scored significantly higher on running distance, maximum speed and the number of top and repeated sprints; the carbohydrate loading group scored significantly lower on player load, metabolic power and running imbalance compared to the control team during their match. CONCLUSIONS Our findings suggest carbohydrate loading enabled elite soccer players to achieve greater running outputs with greater metabolic efficiency and lower fatigue compared to their habitual diets.
Collapse
Affiliation(s)
- Abdolreza Kazemi
- Vali-E-Asr University of Rafsanjan, Dept of Sports Sciences, Faculty of Literature and Humanities, Rafsanjan, Iran
| | - Ghazi Racil
- La Manouba University, Research Unit (UR 17JS01) “Sport Performance, Health & Society” Higher Institute of Sport and Physical Education of Ksar Said, Manouba, Tunis
| | | | - Mohadeseh Behnam Moghadam
- Islamic Azad University, Department of Physical Education & Sport Sciences, Faculty of Humanities, Tehran, Iran
| | - Parisa Karami
- University of Tehra, Department of Physical Education & Sport Sciences, Faculty of Humanities, Tehran, Iran
| | - Menno Henselmans
- The International Scientific Research Foundation for Fitness and Nutrition, Amsterdam, The Netherlands
| |
Collapse
|
4
|
Areta JL. Physical performance during energy deficiency in humans: An evolutionary perspective. Comp Biochem Physiol A Mol Integr Physiol 2023; 284:111473. [PMID: 37406958 DOI: 10.1016/j.cbpa.2023.111473] [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: 03/07/2023] [Revised: 06/29/2023] [Accepted: 06/30/2023] [Indexed: 07/07/2023]
Abstract
Energy deficiency profoundly disrupts normal endocrinology, metabolism, and physiology, resulting in an orchestrated response for energy preservation. As such, despite energy deficit is typically thought as positive for weight-loss and treatment of cardiometabolic diseases during the current obesity pandemic, in the context of contemporary sports and exercise nutrition, chronic energy deficiency is associated to negative health and athletic performance consequences. However, the evidence of energy deficit negatively affecting physical capacity and sports performance is unclear. While severe energy deficiency can negatively affect physical capacity, humans can also improve aerobic fitness and strength while facing significant energy deficit. Many athletes, also, compete at an elite and world-class level despite showing clear signs of energy deficiency. Maintenance of high physical capacity despite the suppression of energetically demanding physiological traits seems paradoxical when an evolutionary viewpoint is not considered. Humans have evolved facing intermittent periods of food scarcity in their natural habitat and are able to thrive in it. In the current perspective it is argued that when facing limited energy availability, maintenance of locomotion and physical capacity are of high priority given that they are essential for food procurement for survival in the habitat where humans evolved. When energetic resources are limited, energy may be allocated to tasks essential for survival (e.g. locomotion) while minimising energy allocation to traits that are not (e.g. growth and reproduction). The current perspective provides a model of energy allocation during energy scarcity supported by observation of physiological and metabolic responses that are congruent with this paradigm.
Collapse
Affiliation(s)
- José L Areta
- Research Institute for Sport and Exercise Sciences, School of Sport and Exercise Sciences, Liverpool John Moores University, UK.
| |
Collapse
|
5
|
Wei RJ, Orbeta L, Hatamiya NS, Chang CJ. Nutritional Strategies for Endurance Cyclists - Periodized Nutrition, Ketogenic Diets, and Other Considerations. Curr Sports Med Rep 2023; 22:248-254. [PMID: 37417661 DOI: 10.1249/jsr.0000000000001085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/08/2023]
Abstract
ABSTRACT Cycling is a growing sport worldwide since the COVID-19 pandemic. With the growing availability and interest in long distance events, professional and amateur cyclists are pushing themselves further and harder than ever before. Training and nutrition should be understood by the sports medicine professional in order to guide counseling toward proper fueling to avoid health consequences. This article reviews macronutrients and micronutrients, periodized training and nutrition, and the relevance of the ketogenic diet for endurance cyclists riding greater than 90 min.
Collapse
Affiliation(s)
| | - Lindsay Orbeta
- Human Performance Center, University of California, San Francisco, San Francisco, CA
| | | | | |
Collapse
|
6
|
Ramonas A, Laursen PB, Williden M, Chang WL, Kilding AE. Carbohydrate intake before and during high intensity exercise with reduced muscle glycogen availability affects the speed of muscle reoxygenation and performance. Eur J Appl Physiol 2023:10.1007/s00421-023-05162-y. [PMID: 36897400 DOI: 10.1007/s00421-023-05162-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 02/16/2023] [Indexed: 03/11/2023]
Abstract
Muscle glycogen state and carbohydrate (CHO) supplementation before and during exercise may impact responses to high-intensity interval training (HIIT). This study determined cardiorespiratory, substrate metabolism, muscle oxygenation, and performance when completing HIIT with or without CHO supplementation in a muscle glycogen depleted state. On two occasions, in a cross-over design, eight male cyclists performed a glycogen depletion protocol prior to HIIT during which either a 6% CHO drink (60 g.hr-1) or placebo (%CHO, PLA) was consumed. HIIT consisted of 5 × 2 min at 80% peak power output (PPO), 3 × 10-min bouts of steady-state (SS) cycling (50, 55, 60% PPO), and a time-to-exhaustion (TTE) test. There was no difference in SS [Formula: see text], HR, substrate oxidation and gross efficiency (GE %) between CHO and PLA conditions. A faster rate of muscle reoxygenation (%. s-1) existed in PLA after the 1st (Δ - 0.23 ± 0.22, d = 0.58, P < 0.05) and 3rd HIIT intervals (Δ - 0.34 ± 0.25, d = 1.02, P < 0.05). TTE was greater in CHO (7.1 ± 5.4 min) than PLA (2.5 ± 2.3 min, d = 0.98, P < 0.05). CHO consumption before and during exercise under reduced muscle glycogen conditions did not suppress fat oxidation, suggesting a strong regulatory role of muscle glycogen on substrate metabolism. However, CHO ingestion provided a performance benefit under intense exercise conditions commenced with reduced muscle glycogen. More research is needed to understand the significance of altered muscle oxygenation patterns during exercise.
Collapse
Affiliation(s)
- Andrius Ramonas
- School of Sports and Recreation, Auckland University of Technology, Sports Performance Research Institute New Zealand (SPRINZ), AUT University, PO Box 92006, Auckland, 1142, New Zealand.
| | - Paul B Laursen
- School of Sports and Recreation, Auckland University of Technology, Sports Performance Research Institute New Zealand (SPRINZ), AUT University, PO Box 92006, Auckland, 1142, New Zealand
| | - Micalla Williden
- School of Sports and Recreation, Auckland University of Technology, Sports Performance Research Institute New Zealand (SPRINZ), AUT University, PO Box 92006, Auckland, 1142, New Zealand
| | | | - Andrew E Kilding
- School of Sports and Recreation, Auckland University of Technology, Sports Performance Research Institute New Zealand (SPRINZ), AUT University, PO Box 92006, Auckland, 1142, New Zealand
| |
Collapse
|
7
|
Talsnes RK, Moxnes EF, Nystad T, Sandbakk Ø. The return from underperformance to sustainable world-class level: A case study of a male cross-country skier. Front Physiol 2023; 13:1089867. [PMID: 36699686 PMCID: PMC9870290 DOI: 10.3389/fphys.2022.1089867] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 12/22/2022] [Indexed: 01/11/2023] Open
Abstract
Purpose: To determine the main factors associated with unexpected underperformance and prospectively describe the holistic process of returning to sustainable world-class level in a male cross-country skier. Methods: Longitudinal training data was retrospectively analyzed across nine seasons (2012-2013 to 2020-2021), and categorized into training forms (endurance, strength, and speed), intensities [low- (LIT), moderate- (MIT), and high-intensity training (HIT)], and modes (specific and non-specific). Performance data was obtained from the International Ski and Snowboard Federation. Following two seasons of unexpected underperformance (2019-2020 and 2020-2021), the participant was prospectively followed in the process of returning to sustainable world-class level (2021-2022). Day-to-day training data and physiological tests were analyzed, and interviews with the participant and the head coach conducted. Results: Longitudinal training data from 2012-2013 to 2018-2019 demonstrated a non-linear 30% increase in total training volume (from 772 to 1,002 h), mainly caused by increased volume of ski-specific endurance training without changes in intensity distribution. Coincidingly, the participant gradually reached a world-class performance level. After two seasons of unexpected underperformance with relatively similar training volumes and intensity distributions as in the preceding seasons, the possible contributing factors were identified: lack of training periodization, limited monitoring and intensity control, particularly in connection with a "extreme" regime of training with low carbohydrate availability and days including two MIT sessions, as well as lack of systematic technique training and follow-up by coaches on a daily basis. Consequently, the return to world-class level included the introduction of a clear micro-cycle periodization, more systematic physiological monitoring and testing, more accurate intensity control, increased carbohydrate intake during and between sessions, as well as increased emphasize on technique training and an assistant coach present during day-to-day training. Conclusion: These longitudinal data describe the main factors leading to unexpected underperformance, in addition to providing unique insights into the corresponding process of returning to sustainable world-class level in a male cross-country skier. The holistic approach described in this case study may serve as a theoretical framework for future studies and practical work with underperforming endurance athletes.
Collapse
Affiliation(s)
- Rune Kjøsen Talsnes
- Department of Sports Science and Physical Education, Nord University, Bodø, Norway,Meråker High School, Trøndelag County Council, Steinkjer, Norway,*Correspondence: Rune Kjøsen Talsnes,
| | - Einar Flaktveit Moxnes
- Centre for Elite Sports Research, Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, Trondheim, Norway
| | - Trond Nystad
- Centre for Elite Sports Research, Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, Trondheim, Norway
| | - Øyvind Sandbakk
- Centre for Elite Sports Research, Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, Trondheim, Norway
| |
Collapse
|
8
|
Wang Y, Zhou K, Wang V, Bao D, Zhou J. The Effects of Concurrent Training Combined with Low-Carbohydrate High-Fat Ketogenic Diet on Body Composition and Aerobic Performance: A Systematic Review and Meta-Analysis. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph191811542. [PMID: 36141816 PMCID: PMC9517144 DOI: 10.3390/ijerph191811542] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 09/05/2022] [Accepted: 09/07/2022] [Indexed: 05/22/2023]
Abstract
(1) Background: Recently, studies have emerged to explore the effects of concurrent training (CT) with a low-carb, high-fat ketogenic diet (LCHF) on body composition and aerobic performance and observed its benefits. However, a large variance in the study design and observations is presented, which needs to be comprehensively assessed. We here thus completed a systematic review and meta-analysis to characterize the effects of the intervention combining CT and LCHF on body composition and aerobic capacity in people with training experience as compared to that combining CT and other dietary strategies. (2) Methods: A search strategy based on the PICOS principle was used to find literature in the databases of PubMed, Web of Science, EBSCO, Sport-discuss, and Medline. The quality and risk of bias in the studies were independently assessed by two researchers. (3) Result: Eight studies consisting of 170 participants were included in this work. The pooled results showed no significant effects of CT with LCHF on lean mass (SMD = -0.08, 95% CI -0.44 to 0.3, p = 0.69), body fat percentage (SMD = -0.29, 95% CI -0.66 to 0.08, p = 0.13), body mass (SMD = -0.21, 95% CI -0.53 to 0.11, p = 0.2), VO2max (SMD = -0.01, 95% CI -0.4 to 0.37, p = 0.95), and time (or distance) to complete the aerobic tests (SMD = -0.02, 95% CI -0.41 to 0.37, p = 0.1). Subgroup analyses also showed that the training background of participants (i.e., recreationally trained participants or professionally trained participants) and intervention duration (e.g., > or ≤six weeks) did not significantly affect the results. (4) Conclusions: This systematic review and meta-analysis provide evidence that compared to other dietary strategies, using LCHF with CT cannot induce greater benefits for lean mass, body fat percentage, body mass, VO2max, and aerobic performance in trained participants.
Collapse
Affiliation(s)
- Yubo Wang
- China Institute of Sport and Health Science, Beijing Sport University, Beijing 100084, China
| | - Kaixiang Zhou
- Sports Health College, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
- Correspondence: (K.Z.); (D.B.); Tel.: +86-178-4459-7198 (K.Z.); +86-139-1199-5047 (D.B.)
| | - Vienna Wang
- College of Engineering, California State University, 1250 Bellflower Boulevard, Long Beach, CA 90840, USA
| | - Dapeng Bao
- China Institute of Sport and Health Science, Beijing Sport University, Beijing 100084, China
- Correspondence: (K.Z.); (D.B.); Tel.: +86-178-4459-7198 (K.Z.); +86-139-1199-5047 (D.B.)
| | - Junhong Zhou
- Hebrew Senior Life Hinda and Arthur Marcus Institute for Aging Research, Harvard Medical School, Boston, MA 02115, USA
| |
Collapse
|
9
|
Anderson L, Drust B, Close GL, Morton JP. Physical loading in professional soccer players: Implications for contemporary guidelines to encompass carbohydrate periodization. J Sports Sci 2022; 40:1000-1019. [DOI: 10.1080/02640414.2022.2044135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Liam Anderson
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
| | - Barry Drust
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
| | - Graeme L. Close
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom St Campus, Liverpool John Moores University, Liverpool, L3 6AF, UK
| | - James P. Morton
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom St Campus, Liverpool John Moores University, Liverpool, L3 6AF, UK
| |
Collapse
|
10
|
Rauch CE, McCubbin AJ, Gaskell SK, Costa RJS. Feeding Tolerance, Glucose Availability, and Whole-Body Total Carbohydrate and Fat Oxidation in Male Endurance and Ultra-Endurance Runners in Response to Prolonged Exercise, Consuming a Habitual Mixed Macronutrient Diet and Carbohydrate Feeding During Exercise. Front Physiol 2022; 12:773054. [PMID: 35058795 PMCID: PMC8764139 DOI: 10.3389/fphys.2021.773054] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 11/16/2021] [Indexed: 12/31/2022] Open
Abstract
Using metadata from previously published research, this investigation sought to explore: (1) whole-body total carbohydrate and fat oxidation rates of endurance (e.g., half and full marathon) and ultra-endurance runners during an incremental exercise test to volitional exhaustion and steady-state exercise while consuming a mixed macronutrient diet and consuming carbohydrate during steady-state running and (2) feeding tolerance and glucose availability while consuming different carbohydrate regimes during steady-state running. Competitively trained male endurance and ultra-endurance runners (n = 28) consuming a balanced macronutrient diet (57 ± 6% carbohydrate, 21 ± 16% protein, and 22 ± 9% fat) performed an incremental exercise test to exhaustion and one of three 3 h steady-state running protocols involving a carbohydrate feeding regime (76-90 g/h). Indirect calorimetry was used to determine maximum fat oxidation (MFO) in the incremental exercise and carbohydrate and fat oxidation rates during steady-state running. Gastrointestinal symptoms (GIS), breath hydrogen (H2), and blood glucose responses were measured throughout the steady-state running protocols. Despite high variability between participants, high rates of MFO [mean (range): 0.66 (0.22-1.89) g/min], Fatmax [63 (40-94) % V̇O2max], and Fatmin [94 (77-100) % V̇O2max] were observed in the majority of participants in response to the incremental exercise test to volitional exhaustion. Whole-body total fat oxidation rate was 0.8 ± 0.3 g/min at the end of steady-state exercise, with 43% of participants presenting rates of ≥1.0 g/min, despite the state of hyperglycemia above resting homeostatic range [mean (95%CI): 6.9 (6.7-7.2) mmol/L]. In response to the carbohydrate feeding interventions of 90 g/h 2:1 glucose-fructose formulation, 38% of participants showed breath H2 responses indicative of carbohydrate malabsorption. Greater gastrointestinal symptom severity and feeding intolerance was observed with higher carbohydrate intakes (90 vs. 76 g/h) during steady-state exercise and was greatest when high exercise intensity was performed (i.e., performance test). Endurance and ultra-endurance runners can attain relatively high rates of whole-body fat oxidation during exercise in a post-prandial state and with carbohydrate provisions during exercise, despite consuming a mixed macronutrient diet. Higher carbohydrate intake during exercise may lead to greater gastrointestinal symptom severity and feeding intolerance.
Collapse
Affiliation(s)
- Christopher E Rauch
- Department of Nutrition, Dietetics and Food, Monash University, Melbourne, VIC, Australia
| | - Alan J McCubbin
- Department of Nutrition, Dietetics and Food, Monash University, Melbourne, VIC, Australia
| | - Stephanie K Gaskell
- Department of Nutrition, Dietetics and Food, Monash University, Melbourne, VIC, Australia
| | - Ricardo J S Costa
- Department of Nutrition, Dietetics and Food, Monash University, Melbourne, VIC, Australia
| |
Collapse
|
11
|
New Horizons in Carbohydrate Research and Application for Endurance Athletes. Sports Med 2022; 52:5-23. [PMID: 36173597 PMCID: PMC9734239 DOI: 10.1007/s40279-022-01757-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/11/2022] [Indexed: 12/15/2022]
Abstract
The importance of carbohydrate as a fuel source for exercise and athletic performance is well established. Equally well developed are dietary carbohydrate intake guidelines for endurance athletes seeking to optimize their performance. This narrative review provides a contemporary perspective on research into the role of, and application of, carbohydrate in the diet of endurance athletes. The review discusses how recommendations could become increasingly refined and what future research would further our understanding of how to optimize dietary carbohydrate intake to positively impact endurance performance. High carbohydrate availability for prolonged intense exercise and competition performance remains a priority. Recent advances have been made on the recommended type and quantity of carbohydrates to be ingested before, during and after intense exercise bouts. Whilst reducing carbohydrate availability around selected exercise bouts to augment metabolic adaptations to training is now widely recommended, a contemporary view of the so-called train-low approach based on the totality of the current evidence suggests limited utility for enhancing performance benefits from training. Nonetheless, such studies have focused importance on periodizing carbohydrate intake based on, among other factors, the goal and demand of training or competition. This calls for a much more personalized approach to carbohydrate recommendations that could be further supported through future research and technological innovation (e.g., continuous glucose monitoring). Despite more than a century of investigations into carbohydrate nutrition, exercise metabolism and endurance performance, there are numerous new important discoveries, both from an applied and mechanistic perspective, on the horizon.
Collapse
|