Inorganic Nitrate: Sex Differences in Muscle Contractile Function and Efficiency
试验速览
- 阶段
- 1 期
- 状态
- 已完成
- 入组人数
- 35
- 试验地点
- 1
- 主要终点
- Muscle function - Maximal knee extensor speed and power determined using isokinetic dynamometry
研究概览
简要总结
Dietary inorganic nitrate, in the form of beet root juice, is a nutritional intervention, considered to be an exercise enhancer due to its capacity to increase Nitric Oxide (NO) bioavailability. Increasing NO bioavailability has been associated with improved mitochondrial respiration, muscle tissue perfusion and contractile function which may lead to improved exercise capacity. However, the majority of the literature is on male subjects. This limits the applicability of this supplement in females. Therefore, our project aims to determine sex-differences and the specific sex-response across the menstrual cycle of dietary nitrate supplementation on exercise efficiency, strength and fatigue resistance.
详细描述
Dietary inorganic nitrate is a nutritional intervention, considered to be an exercise enhancer due to its capacity to increase Nitric Oxide (NO) bioavailability. Increasing NO bioavailability has been associated with improved mitochondrial respiration, muscle tissue perfusion and contractile function which may lead to improved exercise capacity. The amount of research investigating the effects of beet root juice supplementation (which contains a high concentration of inorganic nitrate) on exercise responses has increased dramatically in the last 10 years-with over 150 studies in the literature. To date there are only 7 studies looking at exercise responses following inorganic nitrate supplementation specifically in females. Given the physiological differences between males and females studies looking into sex-differences and the specific sex-response are warranted.
The purpose of this study is to investigate whether dietary nitrate supplementation has different effects on muscle contractile function in males and females. We will assess muscle function during an isokinetic protocol where subjects will have to produce maximum efforts at three different torque development speeds (i.e. 180, 270 and 360). This will be followed with a fatigue protocol which will consist of intermittent voluntary contractions at 60% of their maximal voluntary contraction until exhaustion provided by research in the Sport Medicine - Kinesiology department. Thus, we will be able to distinguish the effect of dietary nitrate on contractile function and its capacity to delay fatigue in a sex-specific manner.
The hypothesis of this study is that there will be a group difference between males and females for change in peak power and time to exhaustion after consuming dietary nitrate (in the form of concentrated beetroot juice) for 5 days.
In order to test this hypothesis, we will recruit 24 healthy recreationally active individuals (12 females + 12 males) in a randomized, double-blind, placebo controlled, cross over design.
Specific Aim 1: Determine the sex-differences of the effect of dietary nitrate supplementation on peak power. We hypothesize that the males will have larger improvement in peak power following dietary nitrate.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Crossover
- 主要目的
- Other
- 盲法
- Double (Participant, Investigator)
入排标准
- 年龄范围
- 18 Years 至 34 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •Male and female participants in good general health as assessed by the standard procedures described below and specifically meeting normal blood pressure range (systolic: 120-129, diastolic: 80-84) and normal BMI range (18.5-24.9)
- •Engaged in physical activity and/or recreational sport but not highly-trained, as assessed by the investigator in personal consultation and laboratory stress test.
- •No orthopedic limitations.
排除标准
- •• Known pulmonary, cardiovascular or metabolic disease
- •Food allergies including phenylketonurea (PKU)
- •Regular use of dietary supplements within 6 months prior to the start of the study
- •Taking any dietary/sport supplements that could affect nitrate metabolism: Sport supplements containing the amino acids L-arginine, L-citrulline, beta-alanine, Creatine, Nitrate based pre-work out supplements
- •Blood donation within 3 months prior to the start of the study
- •Substance abuse within 2 years of the start of the study
- •Hyper- or hypotension medication
- •Pregnant or lactating
- •Not having a regular menstrual cycle (minimum of 10-12 menses per year)
- •Stopped using a contraceptive method or started a new contraceptive method within 3 months.
研究组 & 干预措施
Dietary nitrate
The active treatment, beetroot juice (BEET IT, James White Drinks, Ipswich, UK), contains 6.2mmol of inorganic nitrate. Participants will continue supplementation until they complete all testing visits.
干预措施: concentrated beet root juice (Drug)
Placebo
The placebo beet root juice is made by the same company (BEET IT, James White Drinks, Ipswich, UK) and contains no inorganic nitrate.
干预措施: Placebo beet root juice (Drug)
结局指标
主要结局
Muscle function - Maximal knee extensor speed and power determined using isokinetic dynamometry
时间窗: Male subjects (2 occasions)- It will be measured on day 5 of supplementation (placebo or nitrate). Female subjects (4 times) - It will be measured between days 3-5 and 10-15 of their menstrual cycle in two different cycles.
This is an isokinetic (same speed over range of motion) strength test that will measure peak torque of the quadricep and hamstring (Nm/kg) and average power (W/kg). The testing protocol will be completed at three different speeds 180degrees/second, 270degrees/second and 360degrees/second.
次要结局
- Oxygen consumption during a submaximal exercise(Male subjects (2 occasions)- It will be measured on day 5 of supplementation (placebo or nitrate). Female subjects (4 times) - It will be measured between days 3-5 and 10-15 of their menstrual cycle in two different cycles.)
- Time to exhaustion during a high intensity exercise bout on a cycle ergometer(Male subjects (2 occasions)- It will be measured on day 5 of supplementation (placebo or nitrate). Female subjects (4 times) - It will be measured between days 3-5 and 10-15 of their menstrual cycle in two different cycles.)
研究者
Jason Allen
Professor
University of Virginia