Use of Velocity Monitoring to Prescribe Appropriate Flywheel-based Inertial Training (FIT) Workloads for Exercise in Space Flight
试验速览
- 阶段
- 不适用
- 状态
- 招募中
- 发起方
- 入组人数
- 16
- 试验地点
- 2
- 主要终点
- Voluntary activation
研究概览
简要总结
This study aims to determine how flywheel-based inertial training (FIT) implemented according to principles of velocity-based training (VBT) and High-Intensity Interval Training (HIIT) affects disuse-induced physical de-conditioning including loss of voluntary muscle strength, aerobic capacity, and balance regulation.
详细描述
The primary objectives of this project are:
- To assess how 30d of unilateral lower limb suspension (ULLS) with and without FIT exercise affects voluntary and electrically-evoked twitch force, motor unit recruitment, and anisotropic measures.
- To determine how muscle anisotropy (assessed through diffusion tensor imaging) and motor unit action potential train (MUAPT) characteristics relate to contractile function in loaded and unloaded limbs
Secondary objectives include:
- To assess impact of ULLS with and without FIT on aerobic capacity
- To assess impact of ULLS with and without FIT on balance regulation during single-leg stance
This study aims to recruit 10 healthy, physically active participants (both male and female). Participants will undergo 30d of ULLS to unload the left limb during daily living activities. Subjects will wear a specially modified shoe with a 5cm rocker-style stack on the right leg and ambulate using crutches. Participants will be randomly assigned to either a control or exercise group. Those in the exercise group will perform Flywheel-based Inertial Training (FIT) leg press three times per week. Moment of inertia of the flywheel will be adjusted to elicit movement speeds of 0.4 m/s for resistance training (four sets of 10 repetitions). For High Intensity Interval Training, flywheel moment of inertia will be adjusted to elicit movement speed of 1.0m/s during upright squats (four sets of 3 min).
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Treatment
- 盲法
- None
盲法说明
Participants are unable to be masked to their intervention (exercise v. non-exercise). Although other researchers from this team will be responsible for directly implementing exercise interventions, exercise sessions will be conducted in the same building as the PI's office. Therefore, it is likely that the PI will be aware of which subjects are completing exercise sessions. The PI and his team will be directly responsible for assessing primary and secondary research outcomes.
入排标准
- 年龄范围
- 35 Years 至 45 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •Regularly engaging in aerobic exercise (> 150min/wk) and resistance exercise (>1 time per week) for the past 12 months
- •Education greater than or equal to bachelor's degree (any field)
排除标准
- •Waist circumference < 55cm or > 90cm (F) and < 75cm or > 100cm (M)
- •Body mass index < 18.5 or > 29.9
- •Shoe size < 25 or >29cm.
- •Not regularly engaging in exercise for previous 12 months
- •Tobacco use within previous 6 months
- •Blood clotting disorder
- •Heart arrhythmia
- •Implanted device which could negatively be affected by electrical impulse or strong magnetic field such as pacemaker, internal defibrillator, or cochlear implant
- •Diagnosed cardiovascular, pulmonary, renal, or metabolic disease
- •Pregnancy (within previous 6 months)
- •Oral contraceptive use (within previous three months)
- •High resting blood pressure (>140 systolic and/or > 90 diastolic)
- •Currently or previously undergone gender-affirming therapy (hormone therapy or sexual reassignment surgery)
- •Low back or leg injury in previous 6 months
- •Currently taking medication to assist with sleep
- •Muscle, bone, or joint injury that limits physical activity within previous 6 months
- •Neurological disorder which affects balance (such as multiple sclerosis or Parkinson's disease)
结局指标
主要结局
Voluntary activation
时间窗: Baseline, day 13, and day 30
Voluntary activation of the quadriceps will be assessed with electrical stimulation of the femoral nerve before, during, and after a maximal voluntary isometric contraction (MVIC) using the interpolated twitch technique.
Twitch Properties-Electromechanical Delay
时间窗: Baseline, day 13, and day 30
Electromechanical delay will be calculated as the time difference between the onset of electrical impulse and onset of torque development during femoral nerve stimulation. This will be measured before and after a maximal voluntary isometric contraction.
Twitch Properties-Rate of Torque Development
时间窗: Baseline, day 13, and day 30
Rate of Torque Development will be calculated as the change in torque divided by the change in time in the linear phase between 20 and 80% of peak twitch torque during femoral nerve stimulation. This will be measured before and after a maximal voluntary isometric contraction.
Twitch Properties-Time to peak Tension
时间窗: Baseline, day 13, and day 30
Time to peak tension will be calculated as the time difference between the onset of electrical impulse and peak twitch torque during femoral nerve stimulation. This will be measured before and after a maximal voluntary isometric contraction.
Twitch Properties-Peak Twitch Torque
时间窗: Baseline, day 13, and day 30
Peak twitch torque during femoral nerve stimulation will be calculated as the highest torque output immediately (approximately 200ms) following femoral nerve stimulation. This will be measured before and after a maximal voluntary isometric contraction.
Twitch Properties-Relaxation Rate
时间窗: Baseline, day 13, and day 30
Relaxation rate will be calculated as the change in torque divided by the change in time during the relaxation phase of twitch following femoral nerve stimulation. This will be measured before and after a maximal voluntary isometric contraction.
Post activation Potentiation
时间窗: Baseline, day 13, and day 30
Post-activation will be calculated as the percentage difference in peak twitch torque in femoral nerve stimulation before and after a maximal voluntary isometric contraction.
Motor unit action potential train (MUAPT) firing rate
时间窗: Baseline, day 13, and day 30
Firing rate of individual motor units of the vastus lateralis (VL) will be assessed with high density surface electromyography (EMG) using four-pin high density surface electromyography electrodes. Firing rate at 30, 60, and 90% MVIC will be reported. Motor unit firing rate will also be reported during static stance. Participants will use a screen displaying real-time torque output. Participants will voluntarily increase torque (5 seconds), hold at a pre-determined torque level (10 seconds), and gradually reduce force back to resting (5 seconds) with the knee held in a fixed position. This test will be completed with a 10s isometric hold at 30, 60, and 90% of maximal voluntary isometric force.
Motor unit action potential train (MUAPT) recruitment threshold.
时间窗: Baseline, day 13, and day 30
Recruitment threshold of individual motor units of the VL will be assessed with high density surface electromyography using four-pin high density surface electromyography electrodes. Recruitment threshold will be measured during isometric ramp contractions of the quadriceps Participants will use a screen displaying real-time torque output. Participants will voluntarily increase torque (5 seconds), hold at a pre-determined torque level (10 seconds), and gradually reduce force back to resting (5 seconds) with the knee held in a fixed position. This test will be completed with a 10s isometric hold at 30, 60, and 90% of maximal voluntary isometric force.
Motor unit action potential train (MUAPT) de-recruitment threshold.
时间窗: Baseline, day 13, and day 30
De-recruitment threshold of individual motor units f the VL will be assessed with high density surface electromyography using four-pin high density surface electromyography electrodes. Recruitment threshold will be measured during isometric ramp contractions of the quadriceps Participants will use a screen displaying real-time torque output. Participants will voluntarily increase torque (5 seconds), hold at a pre-determined torque level (10 seconds), and gradually reduce force back to resting (5 seconds) with the knee held in a fixed position. This test will be completed with a 10s isometric hold at 30, 60, and 90% of maximal voluntary isometric force.
Muscle size
时间窗: Baseline and day 30
Muscle size will be measured by MRI. Anatomical MRI scans will allow for assessment of anatomical cross sectional area.
Muscle Physiological cross-sectional area
时间窗: Baseline and day 30
Diffusion tensor imaging (DTI) will be used to assess muscle volume and fascicle length. Physiological cross-sectional area will be calculated as Muscle volume divided by fascicle length.
Muscle Fractional Anisotropy
时间窗: Baseline and day 30
Diffusion tensor imaging (DTI) will be used to assess anisotropic measures. A ratio of the diffusivity in the principal planes will be used to calculate fractional anisotropy.
Muscle Diffusion properties
时间窗: Baseline and day 30
Diffusion tensor imaging (DTI) will be used to assess rate of water diffusion in three principal planes. We will report rates of water diffusion in three ways: 1) mean diffusivity (average rate in all three plane), 2) axial diffusivity (rate of diffusion along primary axis), and 3) radial diffusivity (rate of diffusion perpendicular to the primary axis).
Muscle cross-sectional area (Ultrasound)
时间窗: Baseline, day 13, and day 30
cross-sectional area of the vastus lateralis and rectus femoris will be measured by ultrasonography
Fascicle length
时间窗: Baseline, day 13, and day 30
Panoramic views of the mid-portion of the VL will be measured by ultrasonography
Pennation angle
时间窗: Baseline, day 13, and day 30
Pennation angle of the mid-portion of the vastus lateralis will be assessed by ultrasonography
Voluntary Isokinetic Muscle Strength
时间窗: Baseline, day 13, and day 30
Maximal voluntary isokinetic concentric strength of the knee extensors/flexors and ankle dorsi-/plantar-flexors will be assessed at 60 deg/s
Voluntary Isometric Muscle Strength
时间窗: Baseline, day 13, and day 30
Maximal voluntary isometric strength of the knee extensors/flexors and ankle dorsi-/plantar-flexors will be assessed during a (10 seconds) maximal effort contraction.
次要结局
- Aerobic Capacity(Baseline and day 30)
- Ventilatory Threshold(Baseline and day 30)
- Substrate utilization(Baseline and day 30)
- Body Composition(Baseline and day 30)
- Postural sway area(Baseline, day 13, and day 30)
- Postural Sway Velocity(Baseline, day 13, and day 30)
- Motor unit firing rate - single leg stance(Baseline, day 13, and day 30)
- Change in heart rate at rest(Baseline and day 30)
- Change in blood pressure at rest(Baseline and day 30)
- Change in heart rate variability(Baseline and day 30)
- Change in heart rate recovery after exercise(Baseline and day 30)
研究者
Lance Bollinger
Associate Professor
University of Kentucky