Glycogen Utilization during Running: Intensity, Sex, and Muscle-Specific Responses

Impey, Samuel G.; Jevons, Emily; Mees, G; Cocks, Matt; Strauss, Juliette A.; Chester, Neil; Laurie, Ieva; Target, Darren; Hodgson, Adrian B.; Shepherd, Sam; Morton, James P.

doi:10.1249/mss.0000000000002332

Cited by 16 publications

(17 citation statements)

References 34 publications

(45 reference statements)

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“…Further, to search for a performance difference between dietary interventions, we asked the athletes to perform an interval session involving six repetitions of 800m at a pace equivalent to an exercise intensity of ∼85% VO 2max . Our reasoning was that if the pre-exercise muscle glycogen stores are a critical determinant of exercise performance and if the LCHF diet is associated with lower muscle glycogen concentrations in recreational athletes ( 28 ) (but perhaps not in highly competitive athletes ( 65 )), and since very high rates of muscle glycogen use are measured during 800m repetitions ( 66 ) so that, if significant muscle glycogen depletion can be produced by a high intensity interval session, then any impaired performance of athletes eating the LCHF diet should become apparent in the latter intervals of that session.…”

Section: Discussionmentioning

confidence: 99%

Low and high carbohydrate isocaloric diets on performance, fat oxidation, glucose and cardiometabolic health in middle age males

Prins

Noakes²,

Buga³

et al. 2023

Front. Nutr.

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High carbohydrate, low fat (HCLF) diets have been the predominant nutrition strategy for athletic performance, but recent evidence following multi-week habituation has challenged the superiority of HCLF over low carbohydrate, high fat (LCHF) diets, along with growing interest in the potential health and disease implications of dietary choice. Highly trained competitive middle-aged athletes underwent two 31-day isocaloric diets (HCLF or LCHF) in a randomized, counterbalanced, and crossover design while controlling calories and training load. Performance, body composition, substrate oxidation, cardiometabolic, and 31-day minute-by-minute glucose (CGM) biomarkers were assessed. We demonstrated: (i) equivalent high-intensity performance (@∼85%VO2max), fasting insulin, hsCRP, and HbA1c without significant body composition changes across groups; (ii) record high peak fat oxidation rates (LCHF:1.58 ± 0.33g/min @ 86.40 ± 6.24%VO2max; 30% subjects > 1.85 g/min); (iii) higher total, LDL, and HDL cholesterol on LCHF; (iv) reduced glucose mean/median and variability on LCHF. We also found that the 31-day mean glucose on HCLF predicted 31-day glucose reductions on LCHF, and the 31-day glucose reduction on LCHF predicted LCHF peak fat oxidation rates. Interestingly, 30% of athletes had 31-day mean, median and fasting glucose > 100 mg/dL on HCLF (range: 111.68-115.19 mg/dL; consistent with pre-diabetes), also had the largest glycemic and fat oxidation response to carbohydrate restriction. These results: (i) challenge whether higher carbohydrate intake is superior for athletic performance, even during shorter-duration, higher-intensity exercise; (ii) demonstrate that lower carbohydrate intake may be a therapeutic strategy to independently improve glycemic control, particularly in those at risk for diabetes; (iii) demonstrate a unique relationship between continuous glycemic parameters and systemic metabolism.

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Section: Discussionmentioning

confidence: 99%

Low and high carbohydrate isocaloric diets on performance, fat oxidation, glucose and cardiometabolic health in middle age males

Prins

Noakes²,

Buga³

et al. 2023

Front. Nutr.

View full text Add to dashboard Cite

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“…Whether carbohydrate intakes at the lower end of this spectrum compromise glycogen availability and performance is unknown. Female players have a lower net muscle glycogen utilisation but also a lower capacity for glycogen storage compared to males [ 144 , 145 ]. Thus, intervention-based studies utilising incremental carbohydrate fuelling strategies are warranted in female soccer players.…”

Section: Nutritional Strategies For Female Soccer Playersmentioning

confidence: 99%

Physiological Characteristics of Female Soccer Players and Health and Performance Considerations: A Narrative Review

et al. 2021

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Female soccer has seen a substantial rise in participation, as well as increased financial support from governing bodies over the last decade. Thus, there is an onus on researchers and medical departments to develop a better understanding of the physical characteristics and demands, and the health and performance needs of female soccer players. In this review, we discuss the current research, as well as the knowledge gaps, of six major topics: physical demands, talent identification, body composition, injury risk and prevention, health and nutrition. Data on female talent identification are scarce, and future studies need to elucidate the influence of relative age and maturation selection across age groups. Regarding the physical demands, more research is needed on the pattern of high-intensity sprinting during matches and the contribution of soccer-specific movements. Injuries are not uncommon in female soccer players, but targeting intrinsically modifiable factors with injury prevention programmes can reduce injury rates. The anthropometric and physical characteristics of female players are heterogeneous and setting specific targets should be discouraged in youth and sub-elite players. Menstrual cycle phase may influence performance and injury risk; however, there are few studies in soccer players. Nutrition plays a critical role in health and performance and ensuring adequate energy intake remains a priority. Despite recent progress, there is considerably less research in female than male soccer players. Many gaps in our understanding of how best to develop and manage the health and performance of female soccer players remain.

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“…A final consideration is the extent to which sex-differences in substrate efficiency and body mass impact on race nutrition and the propensity for nutrition-induced GI distress. Owing to their greater dependence on lipid oxidation during exercise (see 2.2 Substrate Utilization), female endurance athletes may be less susceptible to glycogen degradation [212] and its debilitating effects. Better substrate efficiency may also explain, at least in part, the lower carbohydrate and general caloric intakes of females during ultra-endurance competition [213,214].…”

Section: Gut Trainingmentioning

confidence: 99%

Do Sex Differences in Physiology Confer a Female Advantage in Ultra-Endurance Sport?

et al. 2021

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Ultra-endurance has been defined as any exercise bout that exceeds 6 h. A number of exceptional, record-breaking performances by female athletes in ultra-endurance sport has roused speculation that they might be predisposed to success in such events. Indeed, while the male-to-female performance gap in traditional endurance sport (e.g., marathon) remains at ~10%, the disparity in ultra-endurance competition has been reported as low as 4% despite the markedly lower number of female participants. Moreover, females generally outperform males in extreme-endurance swimming. The issue is complex, however, with many sportsspecific considerations and caveats. This review summarizes the sex-based differences in physiological functions and draws attention to those which likely determine success in extreme exercise endeavors. The aim is to provide a balanced discussion of the female versus male predisposition to ultra-endurance sport. Herein, we discuss sex-based differences in muscle morphology and fatigability, respiratory-neuromechanical function, substrate utilization, oxygen utilization, gastrointestinal structure and function, and hormonal control. The literature indicates that while females exhibit numerous phenotypes that would be expected to confer an advantage in ultra-endurance competition (e.g., greater fatigue-resistance, greater substrate efficiency, and lower energetic requirements), they also exhibit several characteristics that unequivocally impinge on performance (e.g., lower O2-carrying capacity, increased prevalence of GI distress, and sex-hormone effects on cellular function/ injury risk).Crucially, the advantageous traits may only manifest as ergogenic in the extreme endurance events which, paradoxically, are the races that females less often contest. The title question should be revisited in the coming years when/if the number of female participants increases. KEY POINTS• Females exhibit numerous physiological characteristics that would be expected to confer an advantage in ultra-endurance competition. However, these traits may only manifest in the extreme distance events that females less often contest• Several aspects of female physiology unequivocally inhibit performance making it unlikely that the fastest females will surpass the fastest males in this sport• More direct physiological comparisons between male and female ultra-endurance athletes are needed, particularly when/if female participation numbers increase

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Glycogen Utilization during Running: Intensity, Sex, and Muscle-Specific Responses

Cited by 16 publications

References 34 publications

Low and high carbohydrate isocaloric diets on performance, fat oxidation, glucose and cardiometabolic health in middle age males

Low and high carbohydrate isocaloric diets on performance, fat oxidation, glucose and cardiometabolic health in middle age males

Physiological Characteristics of Female Soccer Players and Health and Performance Considerations: A Narrative Review

Do Sex Differences in Physiology Confer a Female Advantage in Ultra-Endurance Sport?

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