Muscle Weakness, Quadriceps Muscle Atrophy, Sleep Disturbance
Conditions
Keywords
sleep restriction, spaceflight, unweighting, posture
Brief summary
The goal of this trial is to learn about how restricted sleep and not bearing weight on the leg affects muscle strength and posture control. Participants will walk exclusively on one leg, sleep at differing intervals, and complete posture tests, muscle strength tests, and muscle imaging. Researchers will compare adequate sleep and restricted sleep to see if muscle strength and posture are affected.
Detailed description
During space flight, astronauts experience multiple physiological stimuli (such as microgravity and altered sleep cycles) which independently impair balance and strength. The goal of this project is to determine how these stimuli interact to affect static single-leg balance, balance during dynamic tasks, and muscle recruitment, strength, and remodeling. Subjects (healthy adults age 18-50) will complete 13 days of unilateral lower limb suspension (ULLS, the gold standard analog for measuring space flight in ambulatory subjects). For the final three days of the study, subjects will be randomly assigned (via a matched pairs approach) to either normal sleep (7-9 hours per night) or restricted sleep (5 hours per night). Before and after the study, subjects will complete balance assessments and measures of muscle strength and recruitment. At the end of the study, subjects will also undergo diffusion tensor imaging for the thighs. Balance testing will be conducted by examining sway in center of gravity during single leg stance and when stepping down from a box. Muscle strength and recruitment will be assessed via submaximal and maximal voluntary isometric contractions. Additionally, an interpolated twitch experiment will be performed to assess muscle recruitment and twitch properties. Diffusion Tensor imaging will be used to quantify muscle size and structure. As prophylactic treatment against deep vein thrombosis (the major risk of ULLS), subjects will take an aspirin (81mg daily), wear compression stockings, complete passive range of motion exercises, and use intermittent pneumatic compression devices during sedentary times.
Interventions
BEHAVIORALSleep Restriction
5 hours of sleep for 3 days
BEHAVIORALSleep Adequate
9 hours of sleep for 3 days
Sponsors
Lance Bollinger
National Aeronautics and Space Administration (NASA)
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
NONE
Intervention model description
Subjects will be randomized to different arms via a matched-pairs design using the following criteria: age, sex, and race. Within each arm, the loaded limb will serve as an internal control to assess effects of unloading.
Eligibility
Sex/Gender
ALL
Age
18 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
* Age between 18 and 50 years * Regularly engaging in aerobic exercise (\> 150min/wk) and resistance exercise (\>1 time per week) for the past 12 months * Regularly sleep at least 7 hours per night
Exclusion criteria
* Age \< 18 or \> 50 years * Height between \<150 (F) or \<170 (M) and \> 190 cm (both sexes) * Waist circumference \< 55cm or \> 90cm (F) and \< 75cm or \> 100cm (M) * Body mass index \< 18.5 or \> 27.5 * Do not regularly sleep between 7 and 9 hours each night * Have a known sleep disorder * Not regularly engaging in exercise for previous 12 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)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Percentage in Interpolated Twitch Torque of the Loaded and Unloaded Leg | Baseline and study completion, approximately 14 days | Subjects will sit upright in an isokinetic dynamometer with the knee at 60° flexion. Gel electrode pads will be placed over the femoral nerve and just proximal to the patellar tendon. Square wave, constant current, doublet pulses from an electrical stimulator will be used to evoke twitches prior to, during, and following a maximal voluntary isometric contraction (MVIC). Twitch torque will be measured in Newton-meters (Nm). Outcome data are reported as the percentage change in voluntary activation from baseline. |
| Percent Change in Single Leg Stand (SLS) | Baseline and study completion, approximately 14 days | Balance will be assessed using a dual force plate system. Participants will be asked to stand on one leg and maintain their balance for 15 seconds. Specific outcome measures include percentage change in center of pressure 95% ellipse area (sq. mm) compared to baseline. |
| Muscle Volume | Post-intervention, approximately 14 days after start of study | Diffusion Tensor Imaging (DTI) will be used to quantify muscle volume of the loaded and unloaded leg. Subjects will lay supine, and slightly flex the knee (\~10°) to elongate and straighten the quadriceps. A spine array coil will be placed on the MR-scanner table and a flexible body coil wrapped around the upper thigh and centered over mid-thigh of the dominant leg. Multiple images will be taken. DSI Studio program will be used to analyze raw images. |
| Percent Change in Center of Pressure Velocity During Single Leg Stance | Baseline and study completion, approximately 14 days | Balance will be assessed using a dual force plate system. Participants will stand on one leg on a stable force deck for 15 seconds. The mean Center of Pressure (CoP) velocity will be measured in millimeters per second (mm/s) for loaded and unloaded limbs. Outcomes are reported as the percentage change in mean velocity compared to pre-intervention. |
Countries
United States
Contacts
PRINCIPAL_INVESTIGATORLance Bollinger, PhD
University of Kentucky
Baseline characteristics
| Characteristic | — |
|---|---|
| Age, Continuous | 26.7 Year STANDARD_DEVIATION 10.7 |
| Ethnicity (NIH/OMB) Hispanic or Latino | 1 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 4 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 3 Participants |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants |
| Race (NIH/OMB) Asian | 1 Participants |
| Race (NIH/OMB) Black or African American | 1 Participants |
| Race (NIH/OMB) More than one race | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Race (NIH/OMB) White | 5 Participants |
| Region of Enrollment United States | 9 Participants |
| Sex: Female, Male Female | 2 Participants |
| Sex: Female, Male Male | 5 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | 0 / 0 | 0 / 0 |
| other Total, other adverse events | 0 / 0 | 0 / 0 |
| serious Total, serious adverse events | 0 / 0 | 0 / 0 |
Outcome results
None listed