Myonuclear and satellite cell content of the vastus lateralis and soleus with 70 days of simulated microgravity and the NASA SPRINT exercise program.

We previously observed a range of whole muscle and individual slow and fast myofiber size responses (mean: +4 to -24%) in quadriceps (vastus lateralis) and triceps surae (soleus) muscles of individuals undergoing 70 days of simulated microgravity with or without the NASA SPRINT exercise countermeasures program. The purpose of the current investigation was to further explore, in these same individuals, the content of myonuclei and satellite cells, both of which are key regulators of skeletal muscle mass. Individuals completed 6° head-down-tilt bedrest (BR, = 9), bedrest with resistance and aerobic exercise (BRE, = 9), or bedrest with resistance and aerobic exercise and low-dose testosterone (BRE + T, = 8).

Exercise Training Attenuates the Muscle Mitochondria Genomic Response to Bed Rest.

Purpose: Exercise training during the National Aeronautics and Space Administration 70-d bed rest study effectively counteracted the decline in aerobic capacity, muscle mass, strength, and endurance. We aimed to characterize the genomic response of the participants' vastus lateralis on day 64 of bed rest with and without exercise countermeasures.

Methods: Twenty-two healthy young males were randomized into three groups: 1) bed rest only ( n = 7), 2) bed rest + aerobic (6 d·wk -1 ) and resistance training (3 d·wk -1 ) on standard equipment ( n = 7), and 3) bed rest + aerobic and resistance training using a flywheel device ( n = 8).

NASA SPRINT exercise program efficacy for vastus lateralis and soleus skeletal muscle health during 70 days of simulated microgravity.

The efficacy of the NASA SPRINT exercise countermeasures program for quadriceps (vastus lateralis) and triceps surae (soleus) skeletal muscle health was investigated during 70 days of simulated microgravity. Individuals completed 6° head-down-tilt bedrest (BR, = 9), bedrest with resistance and aerobic exercise (BRE, = 9), or bedrest with resistance and aerobic exercise and low-dose testosterone (BRE + T, = 8). All groups were periodically tested for muscle ( = 9 times) and aerobic ( = 4 times) power during bedrest.

Effects of exercise countermeasures on multisystem function in long duration spaceflight astronauts.

Exercise training is a key countermeasure used to offset spaceflight-induced multisystem deconditioning. Here, we evaluated the effects of exercise countermeasures on multisystem function in a large cohort (N = 46) of astronauts on long-duration spaceflight missions. We found that during 178 ± 48 d of spaceflight, ~600 min/wk of aerobic and resistance exercise did not fully protect against multisystem deconditioning.

Virtual Reality "exergames": A promising countermeasure to improve motivation and restorative effects during long duration spaceflight missions.

Long duration spaceflight missions will require novel exercise systems to protect astronaut crew from the detrimental effects of microgravity exposure. The SPRINT protocol is a novel and promising exercise prescription that combines aerobic and resistive training using a flywheel device, and it was successfully employed in a 70-day bed-rest study as well as onboard the International Space Station. Our team created a VR simulation to further augment the SPRINT protocol when using a flywheel ergometer training device (the Multi-Mode Exercise Device or M-MED).

Teleguided self-ultrasound scanning for longitudinal monitoring of muscle mass during spaceflight.

Loss of muscle mass is a major concern for long duration spaceflight. However, due to the need for specialized equipment, muscle size has only been assessed before and after spaceflight where ~20% loss is observed. Here, we demonstrate the utility of teleguided self-ultrasound scanning (Tele-SUS) to accurately monitor leg muscle size in astronauts during spaceflight.

Disuse-Induced Muscle Loss and Rehabilitation: The National Aeronautics and Space Administration Bed Rest Study.

Objectives: The time course and magnitude of atrophic remodeling and the effects of an acute rehabilitation program on muscle atrophy are unclear. We sought to characterize bed rest-induced leg muscle atrophy and evaluate the safety and efficacy of an acute rehabilitation program.

Design: Prespecified analysis of a randomized controlled trial.

High intensity training during spaceflight: results from the NASA Sprint Study.

Historically, International Space Station (ISS) exercise countermeasures have not fully protected astronauts' musculoskeletal and cardiorespiratory fitness. Although these losses have been reduced on more recent missions, decreasing the time required to perform in-flight exercise would permit reallocation of that time to other tasks. To evaluate the effectiveness of a new training prescription, ISS crewmembers performed either the high intensity/lower volume integrated Sprint resistance (3 d wk) and aerobic (interval and continuous workouts, each 3 d wk in alternating fashion) exercise program ( = 9: 8M/1F, 48 ± 7 y, 178 ± 5 cm, 77.

Venous and Arterial Responses to Partial Gravity.

: Chronic exposure to the weightlessness-induced cephalad fluid shift is hypothesized to be a primary contributor to the development of spaceflight-associated neuro-ocular syndrome (SANS) and may be associated with an increased risk of venous thrombosis in the jugular vein. This study characterized the relationship between gravitational level (G-level) and acute vascular changes. : Internal jugular vein (IJV) cross-sectional area, inferior vena cava (IVC) diameter, and common carotid artery (CCA) flow were measured using ultrasound in nine subjects (5F, 4M) while seated when exposed to 1.

Can Simulated Partners Boost Workout Effort in Long-Term Exercise?

Feltz, DL, Hill, CR, Samendinger, S, Myers, ND, Pivarnik, JM, Winn, B, Ede, A, and Ploutz-Snyder, L. Can simulated partners boost workout effort in long-term exercise? J Strength Cond Res 34(9): 2434-2442, 2020-We tested whether exercising with a stronger simulated (i.e.

Exercise and Testosterone Countermeasures to Mitigate Metabolic Changes during Bed Rest.

Background/objectives: Exercise is a front-line countermeasure used to maintain astronaut health during long-duration spaceflight; however, reductions in metabolic health still occur. Accordingly, we evaluated serial changes in metabolic parameters in a spaceflight analog and evaluated the efficacy of exercise with or without the addition of low-dose testosterone treatment on mitigating adverse metabolic changes.

Subjects/methods: Healthy young (<55 years) men were randomly assigned to one of three groups during 70-days of strict, diet controlled, 6° head-down bed rest: Control (CON, n=9), exercise plus testosterone countermeasure (TEX, n=8), or exercise countermeasure plus placebo (PEX, n=9).

Exercise Countermeasures to Neuromuscular Deconditioning in Spaceflight.

The mechanical unloading of spaceflight elicits a host of physiological adaptations including reductions in muscle mass, muscle strength, and muscle function and alterations in central interpretation of visual, vestibular, and proprioceptive information. Upon return to a terrestrial, gravitational environment, these result in reduced function and performance, the potential consequences of which will be exacerbated during exploration missions to austere and distant destinations such as the moon and Mars. Exercise is a potent countermeasure to unloading-induced physiological maladaptations and has been employed since the early days of spaceflight.

Group dynamics motivation to increase exercise intensity with a virtual partner.

Background: The effect of the Köhler group dynamics paradigm (i.e., working together with a more capable partner where one's performance is indispensable to the team outcome) has been shown to increase motivation to exercise longer at a strength task in partnered exercise video games (exergames) using a software-generated partner (SGP).

A novel approach for establishing fitness standards for occupational task performance.

Purpose: To identify strength and performance thresholds below which task performance is impaired.

Methods: A new weighted suit system was used to manipulate strength-to-body-weight ratio during the performance of simulated space explorations tasks. Statistical models were used to evaluate various measures of muscle strength and performance on their ability to predict the probability that subjects could complete the tasks in an acceptable amount of time.

Association of Exercise and Swimming Goggles With Modulation of Cerebro-ocular Hemodynamics and Pressures in a Model of Spaceflight-Associated Neuro-ocular Syndrome.

Importance: Astronauts on International Space Station missions demonstrate adverse neuro-ocular changes. Reversing a negative translaminar pressure gradient (TLPG) by modulating cerebral blood flow, decreasing intracranial pressure, or increasing intraocular pressure (IOP) has been proposed as potential intervention for spaceflight-associated neuro-ocular syndrome (SANS).

Objective: To examine whether exercise (resistance, moderate-intensity aerobic, and high-intensity aerobic) or artificially increasing IOP is associated with modulated cerebro-ocular hemodynamic and pressure changes during head-down tilt (HDT), an analogue of spaceflight, in healthy adults.

Exercise effects on bed rest-induced brain changes.

Purpose: Spaceflight negatively affects sensorimotor behavior; exercise mitigates some of these effects. Head down tilt bed rest (HDBR) induces body unloading and fluid shifts, and is often used to investigate spaceflight effects. Here, we examined whether exercise mitigates effects of 70 days HDBR on the brain and if fitness and brain changes with HDBR are related.

Exercise Training Mitigates Multisystem Deconditioning during Bed Rest.

Introduction: This study investigated the safety and effectiveness of a new integrated aerobic and resistance exercise training prescription (SPRINT) using two different sets of exercise equipment: a suite of large International Space Station-like exercise equipment similar to what is found on the International Space Station and a single device with aerobic and resistance exercise capability in the spaceflight analog of bed rest (BR).

Methods: Subjects (n = 34) completed 70 d of 6° head down tilt BR: 9 were randomized to remain sedentary (CONT), 9 to exercise training using traditional equipment (EX), 8 to exercise using traditional equipment and low-dose testosterone supplementation (ExT), and 8 to exercise using a combined resistance and aerobic flywheel device. Peak aerobic capacity, ventilatory threshold, cardiac morphology and function (echocardiography), muscle mass (magnetic resonance imaging) and strength/power (isokinetic, leg press, and vertical jump), and bone health (bone mineral density, blood and urine bone markers) were assessed before and after BR.

Efficacy of Testosterone plus NASA Exercise Countermeasures during Head-Down Bed Rest.

Introduction: Prolonged confinement to head-down bed rest (HDBR) results in musculoskeletal losses similar to those observed during long-duration space flight. Exercise countermeasures by themselves have not completely prevented the deleterious losses in muscle mass or function in HDBR or space flight.

Purpose: The objective was to investigate the safety and efficacy of intermittent, low-dose testosterone treatment in conjunction with NASA exercise (SPRINT) countermeasures during 70 d of 6° HDBR.

Physiological and Functional Alterations after Spaceflight and Bed Rest.

Introduction: Exposure to microgravity causes alterations in multiple physiological systems, potentially impacting the ability of astronauts to perform critical mission tasks. The goal of this study was to determine the effects of spaceflight on functional task performance and to identify the key physiological factors contributing to their deficits.

Methods: A test battery comprised of seven functional tests and 15 physiological measures was used to investigate the sensorimotor, cardiovascular, and neuromuscular adaptations to spaceflight.

Myocellular Responses to Concurrent Flywheel Training during 70 Days of Bed Rest.

Purpose: This investigation evaluated myocellular responses to an integrated resistance and aerobic training program during 70 d of bed rest.

Methods: Training was 6 d·wk on a small-footprint gravity-independent flywheel resistance and aerobic device; 3 d of maximal flywheel supine quadriceps and calf exercises with continuous rowing separated by 4 to 6 h, and 3 d of interval rowing. Vastus lateralis (VL) and soleus (SOL) muscle biopsies were obtained from eight healthy males (age, 28 ± 4 yr; BMI, 25 ± 3 kg·m; V˙O2max, 42 ± 6 mL·kg·min) before and after 6° head-down tilt bed rest.

Efficacy of Exercise and Testosterone to Mitigate Atrophic Cardiovascular Remodeling.

Purpose: Early and consistent evaluation of cardiac morphology and function throughout an atrophic stimulus is critically important for the design and optimization of interventions. This randomized controlled trial was designed 1) to characterize the time course of unloading-induced morphofunctional remodeling and 2) to examine the effects of exercise with and without low-dose testosterone supplementation on cardiac biomarker, structural, and functional parameters during unloading.

Methods: Twenty-six subjects completed 70 d of head-down tilt bed rest (BR): 9 were randomized to exercise training (Ex), 8 to EX and low-dose testosterone (ExT), and 9 remained sedentary (CONT).

Overview of the NASA 70-day Bed Rest Study.

Purpose: The purpose of this article was to provide an overview of the National Aeronautics and Space Administration (NASA) 70-day Bed Rest Study. The integrated complement of investigations and the standardized bed rest environment that served as the platform for this study complement are described. Outcomes of the studies will not be presented here but will be reported in separate publications.

Panoramic ultrasound: a novel and valid tool for monitoring change in muscle mass.

Background: The strong link between reduced muscle mass and morbidity and mortality highlights the urgent need for simple techniques that can monitor change in skeletal muscle cross-sectional area (CSA). Our objective was to examine the validity of panoramic ultrasound to detect change in quadriceps and gastrocnemius size in comparison with magnetic resonance imaging (MRI) in subjects randomized to 70 days of bed rest (BR) with or without exercise.

Methods: Panoramic ultrasound and MRI images of the quadriceps and gastrocnemius muscles were acquired on the right leg of 27 subjects (26 male, 1 female; age: 34.

Simulated Partners and Collaborative Exercise (SPACE) to boost motivation for astronauts: study protocol.

Background: Astronauts may have difficulty adhering to exercise regimens at vigorous intensity levels during long space missions. Vigorous exercise is important for aerobic and musculoskeletal health during space missions and afterwards. A key impediment to maintaining vigorous exercise is motivation.

Blood Flow Restricted Exercise Compared to High Load Resistance Exercise During Unloading.

Background: Bed rest studies have shown that high load (HL) resistance training can mitigate the loss of muscle size and strength during musculoskeletal unloading; however, not all individuals are able to perform HL resistance exercise. Blood flow restricted (BFR) resistance exercise may be a novel way to prevent maladaptation to unloading without requiring HL exercise equipment. This study evaluated the muscular training adaptations to HL and BFR resistance training during unilateral lower limb suspension (ULLS), a human limb unloading model.