Advanced Resistive Exercise Device Research Articles

Repeated Horizontal Jumping is a Feasible Exercise Countermeasure for Microgravity

Astronauts who spend prolonged time in microgravity on the International Space Station can experience a significant reduction in physical fitness. Jumping exercises represent a potential solution to this problem as the European Space Agency has demonstrated that the deconditioning effect of long-term bed-rest can be countered with around four minutes per day of jumping. The purpose of this study was to evaluate if repeated jumping is possible in microgravity and if the transmission of impact forces and vibration to the aircraft can be minimised. Five subjects performed repeated jumping on a custom jump sled both in microgravity during a parabolic flight campaign and in normal gravitational conditions. Forces expressed by the user and transmitted to the aircraft were quantified using a bespoke instrumentation system. These results show, for the first time, that repeated horizontal jumping is possible in microgravity, and that force transmission can be minimised by using a custom supine jump sled. The peak effective ground reaction force experienced by the user was sensitive to both the style of jumping used and resistance employed. These results open the door to the next generation of exercise countermeasures for deep space exploration. In particular, we have qualified the High Frequency Impulse for Microgravity (HIFIm) exercise device to a Technology Readiness Level of 6 making it a leading candidate to replace the Advanced Resistive Exercise Device (ARED) which has been in service since 2009.

Change in Lumbar Muscle Size and Composition on MRI with Long-Duration Spaceflight.

Prolonged microgravity results in muscle atrophy, especially among the anti-gravity spinal muscles. How individual paravertebral muscle groups change in size and composition with spaceflight needs further exploration. This study investigates lumbar spine musculature changes among six crewmembers on long-duration space missions using non-invasive measurement of muscle changes with magnetic resonance imaging (MRI). Pre- and post-flight lumbar images were analyzed for changes in cross-sectional area, volume, and fat infiltration of the psoas (PS), quadratus lumborum (QL), and paraspinal [erector spinae and multifidus (ES + MF)]muscles using mixed models. Crewmembers used onboard exercise equipment, including a cycle ergometer (CEVIS), treadmill (T2/COLBERT), and the advanced resistive exercise device (ARED). Correlations were used to assess muscle changes related to exercise modality. There was substantial variability in muscle changes across crewmembers but collectively a significant decrease in paraspinal area (- 9.0 ± 4.8%, p = 0.04) and a significant increase in QL fat infiltration (7.3 ± 4.1%, p = 0.05). More CEVIS time may have protected against PS volume loss (p = 0.05) and PS fat infiltration (p < 0.01), and more ARED usage may have protected against ES+MF volume loss (p = 0.05). Crewmembers using modern onboard exercise equipment may be less susceptible to muscle changes. However, variability between crewmembers and muscle size and quality losses suggest additional research is needed to ensure in-flight countermeasures preserve muscle health.

Bisphosphonate Use May Reduce the Risk of Urolithiasis in Astronauts on Long-Term Spaceflights.

ABSTRACTLong‐duration spaceflight is associated with an increased risk of urolithiasis, and the pain caused by urinary calculi could result in loss of human performance and mission objectives. The present study investigated the risk of urolithiasis in astronauts during 6 months on the International Space Station, and evaluated whether the suppression of bone resorption by the bisphosphonate, alendronate (ALN), can reduce the risk. A total of 17 astronauts were included into the analysis: exercise using the advanced resistive exercise device (ARED) plus weekly oral 70 mg alendronate (ARED+ALN group, n = 7) was compared to resistive exercise alone (ARED group, n = 10). Urine volume decreased in both groups during spaceflight but recovered after return. The ARED group showed increased urinary calcium excretion from the 15th to 30th day of spaceflight, whereas urinary calcium was slightly decreased in the ARED+ALN group. Urinary N‐terminal telopeptide (NTX) and helical peptide (HP) of type I collagen, as bone resorption markers, were elevated in the ARED group during and until 0 days after spaceflight, while there was no elevation in these parameters in the ARED+ALN group. Urinary oxalate and uric acid excretion tended to be higher in the ARED group than in the ARED+ALN group during spaceflight. These results demonstrate that astronauts on long‐duration spaceflights may be at high risk for the formation of urinary calcium oxalate and calcium phosphate stones through increased urinary excretion of oxalate and uric acid, from degraded type I collagen, as well as of calcium from enhanced bone resorption. Our findings suggest that increased bone resorption during spaceflight, as a risk factor for urinary calculus formation, could be effectively prevented by an inhibitor of bone resorption. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Neck Muscle Changes Following Long-Duration Spaceflight.

The effects of long-duration spaceflight on crewmember neck musculature have not been adequately studied. The purpose of this study was to evaluate the changes in the neck musculature on pre-flight and post-flight magnetic resonance imaging (MRI) examinations of six crewmembers on 4- to 6-month missions equipped with the advanced resistive exercise device (aRED). The MRI images were resliced to remove variations in spinal curvature, the cross-sectional area (CSA), and muscle fat infiltration (MFI) of neck musculature at the C1-C2, C4-C5, C7-T1, and T1-T2 intervertebral disc levels were measured bilaterally. Percent changes in the neck muscle CSA and fatty infiltration following spaceflight were calculated, and mixed models were used to assess significance of these changes. Crewmembers on missions equipped with the aRED experienced an average 25.1% increase in CSA for the trapezius muscle at C6-C7, an average 11.5% increase in CSA for the semispinalis capitis muscle at C4-C5, an average 9.0% increase in CSA for the sternocleidomastoid muscle at C4-C5, and an average 23.1% increase in CSA for the rhomboid minor at T1-T2. There were no significant changes in the CSA of the levator scapulae, splenius capitis, rectus capitis posterior major, scalenus anterior, scalenus posterior, scalenus medius, longissimus capitis, or obliquus capitis inferior muscles at the locations measured. None of the muscles analyzed experienced statistically significant changes in fatty infiltration with spaceflight. Our study indicates that long-duration spaceflight conditions are associated with preservation of CSA in most neck muscles and significant increases in the CSAs of the trapezius, semispinalis capitis, sternocleidomastoid, and rhomboid minor muscles. This may indicate that cervical muscles are not subjected to the same degradative effects microgravity imparts on the majority of muscles.

Musculoskeletal Injuries in Astronauts: Review of Pre-flight, In-flight, Post-flight, and Extravehicular Activity Injuries

To provide a comprehensive review of musculoskeletal injuries in astronauts during pre-flight, in-flight (including extravehicular activity), and post-flight periods. The discussion is inclusive of etiology and nature of the injury, preventative measures, and future considerations. The most common injuries were to the hand, shoulder, and back/spine. Patterns and location of injury depend on the phase of flight during which they occurred. Current countermeasures are effective for some concerns, but do not ameliorate all musculoskeletal risks, thus new countermeasure and preventative approaches are warranted in some arenas. During pre-flight preparations, the shoulder is a site with the most concerning injuries, and they occur during extravehicular activity training, usually secondary to interaction with the planar hard upper torso. Suit redesign is under consideration, for both the pre- and in-flight environments. Hand injuries are also common in both pre-flight training and in-flight extravehicular activity. Countermeasures include reducing moisture and protective bandaging of fingertips. Space-adaptation back pain and herniated nucleus pulposus occur in-flight and post-flight, respectively. In-flight exercise countermeasures may mitigate many in-flight and post-flight spinal pathologies. In-flight loss of bone mineral and trabecular architecture can be mediated via both pharmacologic and exercise countermeasures. The advanced resistive exercise device has shown ability to reduce not only bone loss, but also muscular atrophy. Standardized and anonymous injury reporting is essential to track the full range of injuries over time. Participation of physical medicine and orthopedic-trained physicians and therapists, working alongside the ASCR (Astronaut Strength, Conditions, and Rehabilitation) group during astronaut exercise, training, and rehab should be considered value added.

The Effects of Resistance Exercise on Intracranial Pressure

IntroductionOne of the primary health concerns faced by NASA astronauts on board the International Space Station is a decline in visual acuity. It is believed that increases in intracranial pressure (ICP) due to resistive exercise performed on the station's Advanced Resistive Exercise Device (ARED) may contribute to Spaceflight Associated Neuro‐Ocular Syndrome (SANS), also referred to as the Visual Impairment and Intracranial Pressure (VIIP) syndrome. In a manner similar to low level Valsalva exertion, it is hypothesized that ICP would increase during low level resistance exercise.MethodsSix healthy subjects (4 male, 2 female, age: 27 ± 10 years, weight: 77 ± 15 kg) were recruited to perform low‐level resistance exercises in both the seated and supine positions. A Cerebral Cochlear Fluid Pressure analyzer (CCFP) was used to noninvasively measure ICP by assessing tympanic membrane displacement (Vm) in the inner ear following an auditory stimulus. Increased values of Vm correspond to a decrease in ICP. After a 10‐minute acclimation period, a baseline measurement was taken with the subject at rest in the seated position. ICP was then measured during randomized, isometric, overhead shoulder holds with weights of 0lbs, 2lbs, and 5lbs (per hand). This procedure was then repeated in the supine position. ICP was also measured in the 15‐degree head down tilt (HDT) position following a 10‐minute acclimation period. Significant differences between groups were determined at p&lt;0.05 using a Student's T‐test.ResultsThe relative changes in Vm with increased loading by position are shown in Figure 1. Vm decreased by 40% ± 15% (p=0.001) in the HDT position as compared to the supine baseline, showing a predicted, reliable increase in ICP for positional changes. In the seated position, displacement increased slightly from baseline (12% ± 63%, p=0.412) for all subjects across all weight levels, indicating a statistically nonsignificant decrease in ICP. Measurements in the supine position were more consistent, with decreasing Vm (3% ± 3%, p=0.563) for all subjects across all weight levels, indicating a nonsignificant increase in ICP.DiscussionContrary to our hypothesis, measured data showed no significant change in ICP during low level resistance exercise in either the seated or supine positions. Based on these results, resistance exercise may not be the primary contributing factor to the development of SANS in astronauts. This study will form the basis of future investigation into the effects of exercise and ICP in different such as gender, age, and clinical populations. Sensitivity of the CCFP to motion and pulse artifacts will also be addressed to reduce variability between subjects.Support or Funding InformationSupported by NASA grant NNX13AJ12GThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Adaptation to microgravity, deconditioning, and countermeasures.

Humans are generally in standing or sitting positions on Earth during the day. The musculoskeletal system supports these positions and also allows motion. Gravity acting in the longitudinal direction of the body generates a hydrostatic pressure difference and induces footward fluid shift. The vestibular system senses the gravity of the body and reflexively controls the organs. During spaceflight or exposure to microgravity, the load on the musculoskeletal system and hydrostatic pressure difference is diminished. Thus, the skeletal muscle, particularly in the lower limbs, is atrophied, and bone minerals are lost via urinary excretion. In addition, the heart is atrophied, and the plasma volume is decreased, which may induce orthostatic intolerance. Vestibular-related control also declines; in particular, the otolith organs are more susceptible to exposure to microgravity than the semicircular canals. Using an advanced resistive exercise device with administration of bisphosphonate is an effective countermeasure against bone deconditioning. However, atrophy of skeletal muscle and the heart has not been completely prevented. Further ingenuity is needed in designing countermeasures for muscular, cardiovascular, and vestibular dysfunctions.

Exercise in space: the European Space Agency approach to in-flight exercise countermeasures for long-duration missions on ISS.

BackgroundTo counteract microgravity (µG)-induced adaptation, European Space Agency (ESA) astronauts on long-duration missions (LDMs) to the International Space Station (ISS) perform a daily physical exercise countermeasure program. Since the first ESA crewmember completed an LDM in 2006, the ESA countermeasure program has strived to provide efficient protection against decreases in body mass, muscle strength, bone mass, and aerobic capacity within the operational constraints of the ISS environment and the changing availability of on-board exercise devices. The purpose of this paper is to provide a description of ESA’s individualised approach to in-flight exercise countermeasures and an up-to-date picture of how exercise is used to counteract physiological changes resulting from µG-induced adaptation. Changes in the absolute workload for resistive exercise, treadmill running and cycle ergometry throughout ESA’s eight LDMs are also presented, and aspects of pre-flight physical preparation and post-flight reconditioning outlined.ResultsWith the introduction of the advanced resistive exercise device (ARED) in 2009, the relative contribution of resistance exercise to total in-flight exercise increased (33–46 %), whilst treadmill running (42–33 %) and cycle ergometry (26–20 %) decreased. All eight ESA crewmembers increased their in-flight absolute workload during their LDMs for resistance exercise and treadmill running (running speed and vertical loading through the harness), while cycle ergometer workload was unchanged across missions.ConclusionIncreased or unchanged absolute exercise workloads in-flight would appear contradictory to typical post-flight reductions in muscle mass and strength, and cardiovascular capacity following LDMs. However, increased absolute in-flight workloads are not directly linked to changes in exercise capacity as they likely also reflect the planned, conservative loading early in the mission to allow adaption to µG exercise, including personal comfort issues with novel exercise hardware (e.g. the treadmill harness). Inconsistency in hardware and individualised support concepts across time limit the comparability of results from different crewmembers, and questions regarding the difference between cycling and running in µG versus identical exercise here on Earth, and other factors that might influence in-flight exercise performance, still require further investigation.

Isokinetic Strength Changes Following Long-Duration Spaceflight on the ISS.

Long-duration spaceflight results in a loss of muscle strength that poses both operational and medical risks, particularly during emergency egress, upon return to Earth, and during future extraterrestrial exploration. Isokinetic testing of the knee, ankle, and trunk quantifies movement-specific strength changes following spaceflight and offers insight into the effectiveness of in-flight exercise countermeasures. We retrospectively evaluated changes in isokinetic strength for 37 ISS crewmembers (Expeditions 1-25) following 163 ± 38 d (mean ± SD) of spaceflight. Gender, in-flight resistance exercise hardware, and preflight strength were examined as potential modifiers of spaceflight-induced strength changes. Mean isokinetic strength declined 8-17% following spaceflight. One month after return to Earth, strength had improved, but small deficits of 1-9% persisted. Spaceflight-induced strength losses were not different between men and women. Mean strength losses were as much as 7% less in crewmembers who flew after the Advanced Resistive Exercise Device (ARED) replaced the interim Resistive Exercise Device (iRED) as the primary in-flight resistance exercise hardware, although these differences were not statistically significant. Absolute and relative preflight strength were moderately correlated (r = -0.47 and -0.54, respectively) with postflight strength changes. In-flight resistance exercise did not prevent decreased isokinetic strength after long-duration spaceflight. However, continued utilization of ARED, a more robust resistance exercise device providing higher loads than iRED, may result in greater benefits as exercise prescriptions are optimized. With reconditioning upon return to Earth, strength is largely recovered within 30 d.

Computational Prediction of Muscle Moments During ARED Squat Exercise on the International Space Station.

Prevention of muscle atrophy caused by reduced mechanical loading in microgravity conditions remains a challenge for long-duration spaceflight. To combat leg muscle atrophy, astronauts on the International Space Station (ISS) often perform squat exercise using the Advanced Resistive Exercise Device (ARED). While the ARED is effective at building muscle strength and volume on Earth, NASA researchers do not know how closely ARED squat exercise on the ISS replicates Earth-level squat muscle moments, or how small variations in exercise form affect muscle loading. This study used dynamic simulations of ARED squat exercise on the ISS to address these two questions. A multibody dynamic model of the complete astronaut-ARED system was constructed in OpenSim. With the ARED base locked to ground and gravity set to 9.81 m/s², we validated the model by reproducing muscle moments, ground reaction forces, and foot center of pressure (CoP) positions for ARED squat exercise on Earth. With the ARED base free to move relative to the ISS and gravity set to zero, we then used the validated model to simulate ARED squat exercise on the ISS for a reference squat motion and eight altered squat motions involving changes in anterior-posterior (AP) foot or CoP position on the ARED footplate. The reference squat motion closely reproduced Earth-level muscle moments for all joints except the ankle. For the altered squat motions, changing the foot position was more effective at altering muscle moments than was changing the CoP position. All CoP adjustments introduced an undesirable shear foot reaction force that could cause the feet to slip on the ARED footplate, while some foot and CoP adjustments introduced an undesirable sagittal plane foot reaction moment that would cause the astronaut to rotate off the ARED footplate without the use of some type of foot fixation. Our results provide potentially useful information for achieving desired increases or decreases in specific muscle moments during ARED squat exercise performed on the ISS.

Men and women in space: bone loss and kidney stone risk after long‐duration space flight (257.3)

Bone loss on Earth is more prevalent in women than men, leading to the assumption that women may be at greater risk from bone loss during flight. Until recently, the number of women having flown long‐duration missions was too small to allow any type of statistical analysis. We report here data from 42 astronauts on long‐duration missions to the International Space Station, 33 men and 9 women. Bone mineral density (dual‐energy X‐ray absorptiometry), bone biochemistry (from blood and urine samples), and renal stone risk factors were evaluated before and after flight. Data were analyzed in two groups, based on available resistance exercise equipment. The response of bone mineral density to flight was the same for men and women, and the typical decrease in bone mineral density (whole body and/or regional) after flight was not observed for either sex for those using an Advanced Resistive Exercise Device. Bone biochemistry, specifically markers of formation and resorption, generally responded similarly in male and female astronauts. The response of urinary supersaturation risk to space flight was not significantly different between men and women, although risks were typically increased after flight in both groups and risks were generally greater in men than in women before and after flight. Overall, the bone and renal stone responses of men and women to space flight were not different.Grant Funding Source: Funded by the NASA Human Research Program.

Men and Women in Space: Bone Loss and Kidney Stone Risk After Long-Duration Spaceflight

Bone loss, a key concern for long-duration space travelers, is typically considered a female issue. The number of women who have flown long-duration space missions is now great enough to allow a quantitative comparison of changes in bone and renal stone risk by sex. Participants were 42 astronauts (33 men and 9 women) on long-duration missions to the International Space Station. Bone mineral density (by dual-energy X-ray absorptiometry) and biochemical markers of bone metabolism (from blood and urine samples) were evaluated before and after flight. Data were analyzed in two groups, based on available resistance exercise equipment. Missions were 49 to 215 days in duration, flown between 2000 and 2012. The bone density response to spaceflight was the same for men and women in both exercise groups. The bone mineral density response to flight was the same for men and women, and the typical decrease in bone mineral density (whole body and/or regional) after flight was not observed for either sex for those using an advanced resistive exercise device. Biochemical markers of bone formation and resorption responded similarly in male and female astronauts. The response of urinary supersaturation risk to spaceflight was not significantly different between men and women, although risks were typically increased after flight in both groups, and risks were greater in men than in women before and after flight. The responses of men and women to spaceflight with respect to these measures of bone health were not different.

Skeletal health in long-duration astronauts: Nature, assessment, and management recommendations from the NASA bone summit

Concern about the risk of bone loss in astronauts as a result of prolonged exposure to microgravity prompted the National Aeronautics and Space Administration to convene a Bone Summit with a panel of experts at the Johnson Space Center to review the medical data and research evidence from astronauts who have had prolonged exposure to spaceflight. Data were reviewed from 35 astronauts who had served on spaceflight missions lasting between 120 and 180 days with attention focused on astronauts who (1) were repeat fliers on long-duration missions, (2) were users of an advanced resistive exercise device (ARED), (3) were scanned by quantitative computed tomography (QCT) at the hip, (4) had hip bone strength estimated by finite element modeling, or (5) had lost >10% of areal bone mineral density (aBMD) at the hip or lumbar spine as measured by dual-energy X-ray absorptiometry (DXA). Because of the limitations of DXA in describing the effects of spaceflight on bone strength, the panel recommended that the U.S. space program use QCT and finite element modeling to further study the unique effects of spaceflight (and recovery) on bone health in order to better inform clinical decisions.

Benefits for bone from resistance exercise and nutrition in long-duration spaceflight: Evidence from biochemistry and densitometry

Exercise has shown little success in mitigating bone loss from long-duration spaceflight. The first crews of the International Space Station (ISS) used the "interim resistive exercise device" (iRED), which allowed loads of up to 297 lb(f) (or 1337 N) but provided little protection of bone or no greater protection than aerobic exercise. In 2008, the Advanced Resistive Exercise Device (ARED), which allowed absolute loads of up to 600 lb(f) (1675 N), was launched to the ISS. We report dietary intake, bone densitometry, and biochemical markers in 13 crewmembers on ISS missions from 2006 to 2009. Of these 13, 8 had access to the iRED and 5 had access to the ARED. In both groups, bone-specific alkaline phosphatase tended to increase during flight toward the end of the mission (p = 0.06) and increased 30 days after landing (p < 0.001). Most markers of bone resorption were also increased in both groups during flight and 30 days after landing (p < 0.05). Bone densitometry revealed significant interactions (time and exercise device) for pelvis bone mineral density (BMD) and bone mineral content (p < 0.01), hip femoral neck BMD (p < 0.05), trochanter BMD (p < 0.05), and total hip BMD (p < 0.05). These variables were unchanged from preflight only for ARED crewmembers, who also returned from flight with higher percent lean mass and lower percent fat mass. Body mass was unchanged after flight in both groups. All crewmembers had nominal vitamin D status (75 ± 17 nmol/L) before and during flight. These data document that resistance exercise, coupled with adequate energy intake (shown by maintenance of body mass determined by dual-energy X-ray absorptiometry [DXA]) and vitamin D, can maintain bone in most regions during 4- to 6-month missions in microgravity. This is the first evidence that improving nutrition and resistance exercise during spaceflight can attenuate the expected BMD deficits previously observed after prolonged missions.

Musculoskeletal Adaptations to Training with the Advanced Resistive Exercise Device

Resistance exercise has been used as a means to prevent the musculoskeletal losses associated with spaceflight. Therefore, the National Aeronautics and Space Administration designed the Advanced Resistive Exercise Device (ARED) to replace the initial device flown on the International Space Station. The ARED uses vacuum cylinders and inertial flywheels to simulate, in the absence of gravity, the constant mass and inertia, respectively, of free weight (FW) exercise. To compare the musculoskeletal effects of resistance exercise training using the ARED with the effects of training with FW. Previously untrained, ambulatory subjects exercised using one of two modalities: FW (6 men and 3 women) or ARED (8 men and 3 women). Subjects performed squat, heel raise, and dead lift exercises 3 d·wk(-1) for 16 wk. Squat, heel raise, and dead lift strength (one-repetition maximum; using FW and ARED), bone mineral density (via dual-energy x-ray absorptiometry), and vertical jump were assessed before, during, and after training. Muscle mass (via magnetic resonance imaging) and bone morphology (via quantitative computed tomography) were measured before and after training. Bone biomarkers and circulating hormones were measured before training and after 4, 8, and 16 wk. Muscle strength, muscle volume, vertical jump height, and lumbar spine bone mineral density (via dual-energy x-ray absorptiometry and quantitative computed tomography) significantly increased (P ≤ 0.05) in both groups. There were no significant differences between groups in any of the dependent variables at any time. After 16 wk of training, ARED exercise resulted in musculoskeletal effects that were not significantly different from the effects of training with FW. Because FW training mitigates bed rest-induced deconditioning, the ARED may be an effective countermeasure for spaceflight-induced deconditioning and should be validated during spaceflight.

Changes In Muscle Volume And Strength Following 16 Weeks Of Training Using The Advanced Resistive Exercise Device (ARED) And Free Weights

Spaceflight-induced muscle atrophy and loss of muscle strength, particularly in the postural and locomotory muscles, might impair task performance during long-duration space missions and planetary exploration. High-intensity free weight (FW) resistive exercise training attenuates muscle atrophy and strength loss during bed rest, a space flight analog. NASA developed the Advanced Resistive Exercise Device (ARED) to simulate the characteristics of FW exercise (i.e. constant resistance, inertial forces) and to be used as a countermeasure during International Space Station (ISS) missions. PURPOSE: To compare the efficacy of ARED and FW training for inducing muscle hypertrophy and strength gains in ambulatory subjects prior to deploying ARED on the ISS. METHODS: Twenty untrained subjects were assigned to either the ARED (8 males, 3 females) or FW (6 males, 3 females) training group and participated in a periodized training protocol consisting of squat (SQ), heel raise (HR), and deadlift (DL) exercises 3 d·wk-1 for 16 wks. SQ, HR, and DL muscle strength (1RM) was measured before, after 8 wks, and after 16 wks of training. Muscle volume of the vasti group (V), hamstring group (H), hip adductor group (ADD), medial gastrocnemius (MG), lateral gastrocnemius (LG), and deep posterior muscles including soleus (DP) was measured using MRI at pre- and post-training. Consecutive cross-sectional images (10mm slices) were analyzed and summed. Anatomical references insured that the same muscle sections were analyzed pre- and post-training. Two-way repeated measures ANOVAs (p<0.05) were used to test for differences in muscle strength and volume between training devices. RESULTS: SQ, HR, and DL 1RM increased in both FW (mean±SE; SQ: 49±6%, HR: 12±2%, DL: 23±4%) and ARED (SQ: 31±4%, HR: 18±2%, DL: 23±3%) groups. Both groups increased muscle volume in the V (FW: 13±2%, ARED: 10±2%), H (FW: 3±1%, ARED: 3±1%), ADD (FW: 15±2%, ARED: 10±1%), LG (FW: 7±2%, ARED: 4±1%), MG (FW: 7±2%, ARED: 5±2%), and DP (FW: 2±1%; ARED: 2±1%) after training. There were no between-group differences in muscle strength or volume. CONCLUSIONS: The increase in muscle volume and strength following ARED training is not different than FW training. These findings indicate that ARED will likely protect against spaceflight-induced muscle atrophy and strength loss.

Bone Mineral Density Adaptations of the Hip and Spine to Training with the Advanced Resistive Exercise Device and with Free Weights in Ambulatory Subjects

Bone Mineral Density Adaptations of the Hip and Spine to Training with the Advanced Resistive Exercise Device and with Free Weights in Ambulatory Subjects