Investigating the Endocrinological and Physiological Responses to Short-term Reduced Carbohydrate Availability in Males.
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 8
- 试验地点
- 2
- 主要终点
- Changes in blood metabolites/hormones: Testosterone
研究概览
简要总结
Using a randomised crossover design, nine weight-stable men, aged 18 - 40 years old, will be recruited via convenience sampling from the staff and student body of LJMU and local area. Participants will be asked to follow two 4-day (~96 hours) periods of tightly controlled exercise energy expenditure (15 kcal/kg FFM/day [cycling]) and dietary intake (60 kcal/kg FFM/day) to compare a state of 'normal' energy availability (or energy balance; equivalent to 45 kcal/kg FFM/day) with concomitant 1: normal carbohydrate availability ('Normal'; ~60% of dietary intake from carbohydrate) and 2: low carbohydrate availability ('LCHF', ~1.5 g/kg carbohydrate per day, ~70 - 80% dietary intake from fat). This approximates the amount of carbohydrate consumed by an individual in a state of LEA through consuming 10 kcal/kg FFM/day with 50% of intake from carbohydrate, or ~1.5 g/kg/day of carbohydrate. In both experimental phases we will measure endocrine, metabolic and physiological parameters.
详细描述
Rationale:
The primary research question associated with this study is 'What is the impact of an acute period of low carbohydrate availability upon associated physiological and endocrinological markers in a cohort of healthy males?'
Extensive research has been conducted since the 1970s to determine the aetiology behind the concurrent impairment of reproductive function and low bone mineral density that is commonly observed in exercising females (De Souza et al., 2014). This research has determined that chronic low energy availability ('LEA' - the energy available from diet after energy used in exercise has been subtracted) is the key determining factor for the endocrine and physiological responses observed in the Female Athlete Triad (De Souza et al., 2014) model. However, whilst the Male Athlete Triad (Nattiv et al., 2021) and RED-S (Mountjoy et al., 2018) models identify the likely impact of LEA upon males, equivalent research identifying the physiological effects of this state in males is far behind that of females.
Moreover, whilst low energy availability has been identified as the key driver of the physiological dysregulations identified in the Female/Male Athlete Triad and RED-S models, much of the existing research has not adequately delineated between the impact of low energy availability, per se, and low carbohydrate availability. Recent research suggests that low carbohydrate availability, with or without the presence of LEA, may be a driver of the physiological dysregulations identified within the aforementioned models. For example, McKay et al (2021) have shown altered iron and immune responses and impaired exercise performance following 6-days of low carbohydrate (50 - 100 g/day) but ~normal energy availability (40 kcal•kg FFM-1•day-1), whilst no changes were apparent in a LEA (15 kcal•kg FFM-1•day-1, 60% carbohydrate) and a control group. Similarly, Heikura et al (2020) have recently shown that over 3.5 weeks, a ketogenic diet impairs markers of bone turnover compared to an energy-matched high carbohydrate diet in highly trained athletes.
Given that exercise and nutritional interventions are key for improving weight-loss and health of the general population, understanding how reduced energy and/or carbohydrate availability may affect male endocrinology and physiology is of the utmost importance. The effects and mechanisms by which low energy and/or carbohydate availability influences male physiological function therefore requires further research using well-controlled experimental research designs.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Crossover
- 主要目的
- Basic Science
- 盲法
- None
盲法说明
Masking not possible as food quantity/type will vary between interventions.
入排标准
- 年龄范围
- 18 Years 至 40 Years（Adult）
- 性别
- Male
- 接受健康志愿者
- 是
入选标准
- •Gender/Sex: Male
- •Age:18-40
- •Healthy (as determined by pre-participation questionnaires)
- •Regularly Exercising/Aerobically trained (3 + times/week, VO2max >50 ml/kg/min), as determined through participant self-identification via recruitment email/verbal communication and baseline assessment of VO2max)
- •Weight-stable (within 2 kg) for the past 6-months
排除标准
- •Gender/Sex: Female/Other
- •Age - < 18 - > 40
- •Health - Deemed unable to perform exercise (assessed via PAR-Q)
- •Current smoker.
- •Medical Condition - Those with any previous diagnosis of; Osteoporosis/low bone mineral density, cardio-vascular disease, Diabetes Mellitus, Cerebrovascular Disease, blood-related illness/disorder, Asthma or other respiratory illness/disorder, Liver Disease, Kidney Disease, gastrointestinal disease, Eating Disorder or Disordered Eating. Those currently taking prescription medication or unwell with a cold or virus at the time of participation.
- •Those unwilling to adhere to the study's methodological requirements (including adhering to alterations in diet and training - inc. alcohol abstention) from the day prior to intervention onset (24 hrs pre-intervention) to completion of follow-up assessments (day 5).
- •Those following a restrictive diet (e.g. vegans)
- •Those with food allergies and/or food intolerances
- •Training status - Does not train 3 + times/week (over past 6 months on average) and/or have a VO2max >50 ml/kg/min.
- •Any athletes that may be tested for substances on the WADA banned substances list
结局指标
主要结局
Changes in blood metabolites/hormones: Testosterone
时间窗: Days 1, 2, 3, 4 & 5 per intervention
Analysis of changes to circulating testosterone concentrations following short term energy balance with a) normal carbohydrate availability and b) low carbohydrate availability
Changes in blood bone turnover markers: ß-CTX (Bone Resorption)
时间窗: Days 1, 2, 3, 4 & 5 per intervention
Analysis of changes in blood-borne bone (re)modelling marker ß-CTX (Bone Resorption) following short term energy balance with a) normal carbohydrate availability and b) low carbohydrate availability
Changes in blood bone turnover markers: P1NP (Bone Formation)
时间窗: Days 1, 2, 3, 4 & 5 per intervention
Analysis of changes in blood-borne bone (re)modelling marker P1NP (Bone Formation)
次要结局
- Changes in sub-maximal Exercise Energy Expenditure(Days 1, 2, 3, 4 & 5 per intervention)
- Change in resting substrate utilisation(Days 1, 3 and 5 of each intervention)
- Immune function(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in Initial Orthostatic Hypotension (IOH)(Pre- and post-intervention (days 1 and 5) for both intervention)
- Change in subjective hunger(Days 1, 2, 3, 4 & 5 per intervention)
- Change in sexual drive/libido(Pre- and post-intervention (days 1 and 5))
- Changes in sub-maximal exercise substrate utilisation(Days 1, 2, 3, 4 & 5 per intervention)
- Sleep duration and quality(Continuous monitoring during intervention period (5-days))
- Changes in blood metabolites/hormones: Glucose(Days 1, 2, 3, 4 & 5 per intervention)
- Change in Profile of Mood States(Pre- and post-intervention (days 1 and 5) per intervention)
- Physical activity energy expenditure (PAEE)(Continuous monitoring during intervention period (5-days))
- Changes in Body Composition: Body Mass (kg)(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in Body Composition: Body Mass Index (kg/m^2)(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in Body Composition: Fat Mass (kg)(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in Body Composition: Extra-cellular Water/Total Body Water ratio(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in blood metabolites/hormones: Insulin(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in blood metabolites/hormones: glycerol(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in blood metabolites/hormones: Leptin(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in Body Composition: Body Fat Percentage (%)(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in Body Composition: Skeletal Muscle Mass (kg)(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in Body Composition: Total Body Water (l)(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in Body Composition: Total Body Water (%)(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in blood metabolites/hormones: Free fatty Acids(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in blood metabolites/hormones: HDL(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in blood metabolites/hormones: LDL(Days 1, 2, 3, 4 & 5 per intervention)
- Alterations to Intra-muscular lipid profile: lipid droplet morphology(Days 1 & 5 per intervention (pre-post))
- Changes in Body Composition: Extra-cellular Water (l)(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in Body Composition: Extra-cellular Water (%)(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in blood metabolites/hormones: Ketones(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in blood metabolites/hormones: IGF-1(Days 1, 2, 3, 4 & 5 per intervention)
- Alterations to Intra-muscular lipid profile: lipid droplet content(Days 1 & 5 per intervention (pre-post))
- Resting Metabolic Rate(Days 1, 3 and 5 of each intervention)
- Changes in blood metabolites/hormones: Triiodothyronine (T3)(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in Body Composition: Fat Free Mass (kg)(Days 1, 2, 3, 4 & 5 per intervention)
- Changes in blood metabolites/hormones: Cortisol(Days 1, 2, 3, 4 & 5 per intervention)
- Alterations to Intra-muscular lipid profile: lipid droplet associated proteins(Days 1 & 5 per intervention (pre-post))
- Alterations to skeletal muscle glycogen(Days 1 & 5 per intervention (pre-post))