- Open Access
Effect of trunk exercise upon lumbar IVD height and vertebral compliance when performed supine with 1 g at the CoM compared to upright in 1 g
BMC Sports Science, Medicine and Rehabilitation volume 14, Article number: 177 (2022)
Spinal unloading in microgravity is associated with stature increments, back pain, intervertebral disc (IVD) swelling and impaired spinal kinematics. The aim of this study was to determine the effect of lateral stabilization, trunk rotation and isometric abdominal exercise upon lumbar IVD height, and both passive and active vertebral compliance when performed supine on a short-arm human centrifuge (SAHC)—a candidate microgravity countermeasure—with 1 g at the CoM, compared to that generated with equivalent upright exercise in 1 g.
12 (8 male) healthy subjects (33.8 ± 7 years, 178.4 ± 8.2 cm, 72.1 ± 9.6 kg) gave written informed consent. Subjects performed three sets of upper body trunk exercises either when standing upright (UPRIGHT), or when being spun on the SAHC. Lumbar IVD height and vertebral compliance (active and passive) were evaluated prior to SAHC (PRE SAHC) and following the first SAHC (POST SPIN 1) and second Spin (POST SPIN 2), in addition to before (PRE UPRIGHT), and after upright trunk exercises (POST UPRIGHT).
No significant effect upon IVD height (L2–S1) when performed UPRIGHT or on the SAHC was observed. Trunk muscle exercise induced significant (p < 0.05) reduction of active thoracic vertebral compliance when performed on the SAHC, but not UPRIGHT. However, no effect was observed in the cervical, lumbar or across the entire vertebral column. On passive or active vertebral compliance.
This study, the first of its kind demonstrates that trunk exercise were feasible and tolerable. Whilst trunk muscle exercise appears to have minor effect upon IVD height, it may be a candidate approach to mitigate—particularly active—vertebral stability on Earth, and in μg via concurrent SAHC. However, significant variability suggests larger studies including optimization of trunk exercise and SAHC prescription with MRI are warranted.
North Rhine ethical committee (Number: 6000223393) and registered on 29/09/2020 in the German Clinical Trials Register (DRKS00021750).
Spinal unloading in microgravity (μg) is associated with stature increments of varying magnitude up to seven cm  and transient (up to 4 days) moderate-to-severe (mainly Lumbar) back pain  in the majority (53–68%) of astronauts. Whilst the specific pathophysiological mechanisms underlying stature increments and back pain are unknown, spaceflight is associated with intervertebral disc (IVD) changes , including swelling , trunk muscle atrophy , reduced para-spinal muscle tone , spinal curvature flattening  and impaired spinal kinematics . Such changes may also contribute to increased vertebral column vulnerability that could support an apparent increased risk of IVD herniation  event that is debilitating on Earth but could be critical when landing on the Moon.
Some astronauts have, due to increased stature, experienced difficulties fitting into designated extra-vehicular activity (EVA) suits, and prior to returning to Earth, their bespoke Soyuz Kazbek seat pan . Despite the clear operational significance, and significant lumbar IVD pathology being observed with Magnetic Resonance Imaging (MRI) following long duration spaceflight , very few spinal evaluation studies have been performed inflight . However, a novel in-flight ultrasonic protocol developed by NASA  was employed in seven long-duration astronauts; identifying 14 features of IVD pathology, including disk desiccation and osteophytes not observed pre-flight . However, no significant changes in IVD height or angle were observed , despite dynamic Lumbar IVD changes being reported in response to diurnal loading , exercise-induced loading  and even simple re-orientation  on Earth.
Changes in body position  or gravitational loading  have also been demonstrated to rapidly modulate vertebral stiffness—defined as the vertebral column’s resistance to deformation . Vertebral compliance is posture-dependent  with postural muscle activation associated with weight-bearing leading to the term ‘active’ vertebral stiffness when upright, and ‘passive’ when prone and thus non-axial load bearing . In fact, a recent parabolic flight study reported acute increments in lumbar (L3) vertebral compliance during transient (~ 20 s) μg, with comparable reductions in vertebral compliance during hypergravity (~ 1.8 g) when standing ‘upright’. However, the effects of loading associated with exercise in varying gravitational environments is unknown.
Indeed, whilst some of the spinal column changes (or their apparent absence) following long-duration (~ 6 months) missions  may reflect gravitational exposure associated with re-entry and landing  life on the International Space Station (ISS) does not mean that the spinal column is continuously unloaded . In fact, the in-flight exercise countermeasures  intended to ameliorate multi-systems de-conditioning i.e., resistive exercise (Advanced Resistive Exercise Device: ARED) and aerobic training (T2—treadmill) also results in repeated exposure to transient (and potentially high instantaneous) axial loading, even though it does not target the spine, or trunk musculature . Whilst it is likely that such exercise affects IVD geometry and may contribute to IVD pathology and vertebral vulnerability, the effect of exercise in non-1 g gravitational loading is unknown .
Despite the extensive time and resources expended by astronauts performing exercise countermeasures, to variable degrees on the ISS , significant deconditioning remains an issue, particularly in the musculoskeletal , neuro-motor , and cardiorespiratory systems . Furthermore, no current in-flight exercise countermeasures targeted maintaining vertebral column function—thus significant post-flight para-spinal muscle atrophy [5, 6] and trunk muscle dysfunction  is observed, including exaggerated vertebral stiffness . Thus, development of novel in-flight countermeasures that are not only more effective at mitigating multi-system de-conditioning, in addition to protecting the vertebral column are warranted, despite future spaceflight resources including mass and volume, being more constrained than currently on the ISS .
Re-imposition of axial ‘gravitational-like’ forces has been proposed via elasticated body suits [29, 30]. Indeed, ‘SkinSuits’ have been shown to reduce stature on Earth , tolerable in μg , and whose intermittent donning may promote vertebral column functionality, including IVD geometry by inducing moderate axial reloading . However, such approaches are unlikely to mitigate multi-systems deconditioning. Provision of Artificial Gravity (AG) via short-arm human centrifugation (SAHC) has been proposed as a potential approach to ameliorate multi-systems de-conditioning, including the vertebral column .
Data from several short-duration head down bed rest (HDBR) studies (the most common ground-based microgravity analogue) suggest that passive AG exposure may have protective effects on induced musculoskeletal de-conditioning  and orthostatic intolerance . Daily passive AG at 1 g at the Centre of Mass (CoM) has also been reported to be both tolerable and acceptable . However, 30 min of daily 1 g at CoM AG provides a low physiological load , and thus appears to be ineffective at ameliorating HDBR-induced multi-systems deconditioning [39, 40].
Performance of exercise during AG has been associated with disorientation, motion sickness  and orthostatic intolerance . However, when the g load is moderate (i.e., around 1 g at CoM), and body motion is voluntary and head movements are consistent with it—e.g., squatting—movement is well tolerated and motion sickness suppressed . Interestingly, following squatting during AG with 1.5 g at the CoM significant lumbar IVD compression was observed [unpublished observations 44].
On Earth, trunk exercises that activate core stabilizer muscles are prescribed in an attempt to mitigate back pain  and promote spinal-related functionality . For example, lateral stabilization and trunk rotation (wood chopper) exercises have been proposed as effective interventions for low back pain . Furthermore, isometric abdominal exercises that activate transversus abdominis (TrA) promote local dynamic spine stability . Yet the effect of such exercise on IVD geometry is unknown. Furthermore, it is reported that the activation of trunk muscles, when supporting loads, can reduce active vertebral compliance .
Thus, performance of lateral stabilization, trunk rotation and isometric abdominal exercises during concurrent axial loading induced by AG is a novel candidate approach to address μg—induced back pain and vertebral column dysfunction. However, whether such exercises generate IVD height compression and vertebral compliance modulation consistent with comparable exercise when upright in 1 g is unknown.
The aim of the study was to determine the effect of lateral stabilization, trunk rotation and isometric abdominal exercise upon lumbar IVD height, and both passive and active vertebral compliance when performed supine on a SAHC with 1 g at the CoM, compared to that generated with equivalent upright exercise in 1 g.
12 (8 male) healthy subjects (33.8 ± 7 years, 178.4 ± 8.2 cm, 72.1 ± 9.6 kg) gave written informed consent to participate in the study approved by the North Rhine ethical committee (Number: 6000223393) and registered on 29/09/2020 in the German Clinical Trials Register (DRKS00021750). Prior to inclusion in the study, all subjects completed a centrifuge medical screening which included blood tests, urine analysis, medical history, and both a resting and treadmill-based stress test ECG. All subjects were recreationally active, including performance of sports-based physical activity at least twice per week.
The study was performed at the short-arm human centrifuge (SAHC) within the: Envihab facility at the German Aerospace Center (DLR) in Cologne (Germany). SAHC is designed for a maximum radial acceleration of 6 g at outer perimeter (i.e., at the feet). During the ramp up/down phases (de)acceleration did not exceed 5°s−2 to minimize the risk of vestibular-induced tumbling sensations. On the centrifuge, participants were secured in a supine position on a horizontal sledge system against a fixed footplate and were instructed to avoid unnecessary head movements during centrifugation to minimize the provocation of disorientation/motion sickness symptoms.
Subjects attended the facility on two occasions, on non-sequential days following the initial medical screening. Each session included performance of three sets of upper body exercise trunk exercises: lateral stabilization (contralateral), trunk rotation (wood chopper) and abdominal isometric when standing upright (UPRIGHT) (Figs. 1, 2a), and during being spun when supine on the SAHC at an angular velocity sufficient to generate 1 g at that individual’s CoM (SAHC) (Fig. 2b) in a randomized order. The SAHC condition consisted of 2 separate centrifuge runs, one clockwise (CW), and the other counter-clockwise (CCW) which were also randomised, although the order of the exercises within each condition was consistent.
In each condition three sets of 20, contralateral exercises (10 each side) were performed, with the arms stretched out holding TRX-bands (TRX Training, USA) while standing one-legged on a balance air pillows (Sissel, Germany), alternating the support leg after each five-second hold. Three sets of 40 (20 each side) wood chopper exercises (involving upper body rotation) with resistance provided by holding resistance bands (TheraBand® 3–4.3 lbs, TheraBand, USA) on each side were also performed. Finally, three sets of 20 abdominal isometric exercises involving a ‘push-down’ movement holding TRX-bands with both hands in front of the abdomen were performed, with each set separated by 60 s of rest.
For the SAHC session, having been familiarised, subjects were instrumented, and lay supine secured (with a hip safety belt) on a sledge, which allowed motion along the SAHC radius with minimal friction. Each subject’s head was orientated towards the centre of rotation with their feet placed on force plates mounted on the end of the centrifuge arm. Subjects lay supine for 5 min (PRE SAHC) on the stationary SAHC, before being spun for 10 min (with 30 s ramp up/down phases) separated by a 15-min break between the two SAHC runs.
Participants were asked to report any back pain, or discomfort in either condition.
Lumbar IVD height and vertebral compliance (when passive (supine) and active (upright)) were evaluated prior to SAHC (PRE SAHC) and following the SPIN 1 (Clockwise; CW). Vertebral compliance was recorded after SPIN 2 (Counter-clockwise; CCW) (POST SAHC) because participants were secured with a hip safety belt and thus were unable to turn over between runs, in addition, to before (PRE UPRIGHT), and after upright trunk exercise performance (POST UPRIGHT).
Lumbar IVD height from L1 to S1 (L1–L2, L2–L3, L3–L4, L4–L5, L5–S1) was assessed via portable ultrasound (Lumify, Philips, Netherlands) with a curvilinear array probe (5–15 MHz) connected to a Galaxy S2 tablet (Samsung, South Korea) when lay prone on a clinical couch. At least two images per level were acquired: one high gain and one low gain allowing estimation of respective anterior IVD height (long axis) (Fig. 3).
Vertebral compliance from C1–L5 was assessed in active (when upright) and passive (prone) conditions with a handheld differential vertebral compliance transducer (PulStar, Sense Technology Inc., USA) manually placed and held perpendicularly upon each vertebral spinous process. To trigger the vertebral compliance measurement, a preload of (18 N)  was applied to compress the soft tissue components between the transducer head and the target spinous process [49, 50]. The triggered impulse propagation properties reflect vertebral compliance  captured via dedicated software (PulStarFRAS, Sense Technology Inc., USA). Resultant vertebral compliance (C1 to L5) is reported to possess good- test-rest reliability even with trained novice examiners , with excellent reliability across the spine . Assessment at each spinous process was performed twice and averaged .
All data was normally distributed (Shapiro Wilk’s test). The effect of upright trunk exercise performance upon IVD height (PRE UPRIGHT vs. POST UPRIGHT) in 1 g was evaluated with paired t-tests. The effect trunk exercise upon IVD height during 1 g at CoM generated by SAHC was evaluated by a one-way ANOVA (PRE SAHC, POST SPIN 1 and POST SPIN 2). As no specific effect of SPIN was evident, the mean effect of trunk exercise during SAHC with 1 g at the CoM (ΔPOST SAHC − PRE SAHC) was compared with that generated when performed upright in 1 g (ΔPOST UPRIGHT − PRE UPRIGHT) via paired t-tests.
Passive and active vertebral compliance were compared in the UPRIGHT and SAHC conditions by paired t-tests. The effect of trunk exercise performance upon active and passive vertebral compliance when upright (PRE UPRIGHT vs. POST UPRIGHT) and on the SAHC (PRE SAHC vs POST SPIN 2) was compared across the entire column and each spinal segment (cervical, thoracic and lumbar) by paired t-tests. As there was no additional effect of Spin 2 the overall effect was calculated by deltas (Δ) (POST–PRE). Changes in passive and active vertebral compliance were compared between UPRIGHT and SAHC with paired t-tests.
Data are reported as mean ± standard error of the mean (SEM). All statistical tests were conducted using IBM SPSS version 21 (IBM Corp., USA). P < 0.05 was assumed to indicate statistical significance with Hedge’s g effect sizes reported to further contextualise the data. Hedge’s g can be used for ‘paired’ effect size calculations when the sample sizes are low, with 0.2, 0.5 and 0.8 being defined as small, medium and large, respectively (based on 1 indicating a group difference equal to 1 standard deviation of the mean) .
All 3 trunk exercises were well tolerated by the subjects in both the UPRIGHT and SAHC 1 g at CoM conditions. No participant reported back pain, or discomfort in either condition. One participant demonstrated pre-syncopal symptoms during SAHC that were mitigated by performance of calf-raises for 1 min under the direction of the supervising physician. No centrifuge run or exercise session was terminated.
IVD image quality was satisfactory except for the level L1–L2, and thus is not reported. No significant difference in IVD height was observed across levels L2 to S1 following trunk muscle exercise performed upright in 1 g (UPRIGHT), although there was a trend (p = 0.058) for L2–L3 height reductions with a ‘large’ hedge’s g (1.39) effect size (Table 1).
No effect of trunk exercise performance during SAHC (with 1 g at the CoM) was observed across L2 to S1 IVD height (Table 2). Thus, the second spin had no additional demonstrable effect.
No significant differences in IVD height changes induced by trunk exercise when upright (ΔPOST UPRIGHT − PRE UPRIGHT) vs. SAHC (ΔPOST SAHC − PRE SAHC) were observed (Table 3). However, a greater reduction in L2–L3 IVD height UPRIGHT compared to SAHC had a ‘large’ Hedge’s g (0.73) effect size.
Active vertebral compliance (Newtons) was significantly greater than passive vertebral compliance (with ‘large’ Hedge’s g effect sizes) in each spinal segment (cervical, thoracic and lumbar) and across the entire column prior to both conditions (Table 4).
Trunk muscle exercise during UPRIGHT and SAHC failed to induce significant reductions in passive vertebral compliance in the entire column, cervical, thoracic, or lumbar regions (Table 5). However, UPRIGHT trunk exercise induced reduced passive vertebral compliance with ‘large’ Hedge’s g effect sizes in all regions (and entire column), except for the lumbar region.
UPRIGHT trunk muscle exercise induced significant reductions (with ‘medium’ Hedge’s g effect sizes) in thoracic, but not cervical, lumbar, or entire column active vertebral compliance (Table 6). Similarly, significant reductions in thoracic active vertebral compliance were induced (with ‘large’ Hedge’s g effect sizes) by trunk muscle exercise during SAHC, but not in the cervical, lumbar, or entire column.
No significant differences (or strong Hedge’s g) were observed Δ (POST–PRE) between UPRIGHT and SAHC in passive or active vertebral compliance over the entire column, cervical, thoracic or lumbar segments.
The present study sought to determine the effect of lateral stabilization, trunk rotation and isometric abdominal exercises upon lumbar IVD height, and both passive and active vertebral compliance when performed supine on a SAHC with 1 g at the CoM, compared to that generated with equivalent upright exercise in 1 g.
The main findings of the study were that trunk (lateral stabilization, trunk rotation and isometric abdominal) exercises were feasible and tolerable but had no significant effect upon IVD height (L2–S1) when performed upright or supine on the SAHC with 1 g at the CoM. However, a ‘large’ hedge’s g effect size was observed for L2–L3 compression following UPRIGHT trunk exercise. Active vertebral compliance was significantly greater than passive across the entire column and in each spinal (cervical, thoracic and lumbar) segment prior to both UPRIGHT and SAHC trunk muscle exercise. Trunk muscle exercise failed to induce significant reduction of passive vertebral compliance when performed UPRIGHT, although ‘large’ Hedge’s g effect sizes were observed in all but the lumbar region. UPRIGHT and SAHC trunk muscle exercise induced significant reductions in thoracic, but not cervical, lumbar, or entire column active vertebral compliance with no differences between conditions.
No reports of discomfort, pain or motion sickness were observed in either condition, suggesting that the performance of lateral stabilization, trunk rotation and isometric abdominal exercises is compatible with SAHC with 1 g at the CoM.
Effects on intervertebral disc height
Trunk (lateral stabilization, trunk rotation and isometric abdominal) exercises had no effect upon IVD height (L2–S1) when performed upright, or supine on the SAHC with 1 g at the CoM. However, following UPRIGHT trunk exercise reduction of L2–L3 height had a ‘large’ hedge’s g effect size. In addition, a ‘large’ hedge’s g effect size was reported for L2–L3 IVD height reductions POST SAHC compared to UPRIGHT. This suggests that the lower lumbar region appears most sensitive and that loading during SAHC was less effective than UPRIGHT.
Interestingly, IVD compression—in particular lower lumbar—has been observed following re-orientation , diurnal loading on Earth  and exercise-induced loading [14, 55]. However, this data was acquired with MRI, which is more sensitive and less subject to investigator error than ultrasound. Our data was captured with ultrasound as MRI is currently not compatible with spaceflight. Whilst this study suggests functionally significant IVD compression was not induced, we have previously observed significant disc compression following squatting during SAHC with 1 g, and to a greater extent 1.5 g at the CoM [unpublished observations 44]. Thus, follow up studies with MRI are warranted.
The magnitude of IVD compression may depend on the muscle volume pressure exerted on the vertebral column . For example, an axial load ≥ 45% of body weight can lead to spinal motor control changes capable of modulating lumbar geometry . However, the muscle volume pressure exerted on the vertebral column associated with our trunk muscle exercise is presumably low and broadly distributed . Indeed, IVD compression has been shown to depend upon loading characteristics including direction, frequency magnitude and duration  with axial loading and exercise shown to provide compression forces that significantly differ between segments and vertebra .
Interestingly, we failed to observed compression in the larger lower IVDs (e.g., L5–S1) which are considered more sensitive to acute (gravitational) loading [unpublished observation 44, 58]. This is expressed in the L5–S1 disc possessing the lowest proteoglycan content, and thus lowest swelling pressure . Indeed, posture has been demonstrated to possess a dramatic effect on IVD pressures  with Wilke et al. reporting IVD pressures of 0.1 Mpa when lying prone, and 0.5 when standing . Such measures may inform modelling of potential effects upon IVD hydration and/or protein content.
Intervertebral aging is associated by dehydration and protein depletion [62,63,64] and thus an increased risk of IVD herniation similar to chronic spinal unloading [65, 66]. In fact, whilst long term HDBR has been shown to increase spinal length and IVD area, with reduced IVD angles, 30 min daily passive SAHC with 1 g at the CoM had no significant effect , similar to other musculoskeletal parameters [39, 40]. Whether trunk muscle exercise is more effective is unknown, however core-strengthening exercise has been shown to remodel IVD content, with repeated loading, such as that experienced by athletes associated with increased glycosaminoglycan content  in contrast to reduced content observed in individuals with IVD pathology on Earth  and in space .
Observed IVD compression was minor, but this coupled with changes in spinal column curvature  may have induced changes in stature. Unfortunately, stature could not be measured accurately on the SAHC. However, whilst SAHC at 1 g at the CoM is potentially compatible with exploration missions  it appears insufficient to mitigate extra-vehicular activity (EVA) suit donning, and Soyuz Kazbek seat pan fit issues  associated with μg-induced stature increments .
Effects on vertebral compliance
Active vertebral compliance was significantly greater than passive vertebral compliance across the entire column and in each spinal (cervical, thoracic and lumbar) segment prior to both UPRIGHT and SAHC trunk muscle exercise. This finding is consistent with previous reports when moving from prone to upright  as biomechanical changes including increased trunk muscle tensions and IVD pressures lead to elevated spinal stiffness .
In our study, trunk muscle exercise failed to induce significant reduction of passive vertebral compliance when performed UPRIGHT. However, ‘large’ Hedge’s g were observed across the entire column, the cervical and thoracic regions, but not lumbar. No such effects were observed during SAHC with 1 g at the CoM suggesting that whilst a greater number of subjects may have yielded significant reductions when UPRIGHT, no such effect is likely with 1 g SAHC. Differences in spinal control are evident in vitro  compared with in vivo . In vitro studies test passive structural elements such as connective tissue compliance tension, but neglect muscle activity—a critical contributor to net vertebral stabilisation . Therefore, passive vertebral compliance tending not to reduce as markedly as active vertebral compliance suggests that evaluation of the dynamics of trunk muscle contributions must be considered .
UPRIGHT and SAHC trunk muscle exercise induced significant acute reduction in thoracic, but not cervical, lumbar, or entire column active vertebral compliance, with no differences between conditions. In fact, reductions in active vertebral compliance are consistent with those reported when donning a backpack  or via axial loading , and during a recent parabolic flight where vertebral compliance reductions were observed during hypergravity (~ 1.8 g) when standing ‘upright’ . Our set of exercises were determined to target activation of vertebral stabilizers , therefore their activation is likely to redistribute load , potentially decreasing vertebral stiffness . However, this hypothesis needs further research as a significant inter-subject variability in vertebral compliance measures has been observed , a potential confound given the relatively low sample size of the current study.
Cyclic flexion–extension in lumbar viscoelastic tissues also induces vertebral compliance reduction . However, the failure to observe significant effects by lateral stabilization, trunk rotation and isometric abdominal exercises may be due to the fact that they predominantly recruit muscles operating upon the thoracic vertebrae. Indeed, further evaluation of the specific effect of candidate exercises is warranted to inform definition of exercise prescriptions targeted at ameliorating acute vertebral control issues  and impaired spinal kinematics —at least of the thoracic vertebrae—with, and without SAHC.
This study, the first of its kind demonstrates that trunk (lateral stabilization, trunk rotation and isometric abdominal) exercises were feasible and tolerable but had no significant effect upon IVD height (L2–S1) when performed upright or supine on the SAHC with 1 g at the CoM identifiable by ultrasound. However, ‘large’ hedge’s g effect sizes were observed for UPRIGHT induced L2–L3 reductions. Active vertebral compliance was significantly greater than passive across the entire column and in each spinal (cervical, thoracic and lumbar) segment prior to both UPRIGHT and SAHC trunk muscle exercise. Trunk muscle exercise failed to induce significant reduction of passive vertebral compliance when performed on the SAHC and UPRIGHT, although ‘large’ Hedge’s g effect sizes were observed in all but the lumbar region for UPRIGHT. UPRIGHT and SAHC trunk muscle exercise induced significant reductions in thoracic, but not cervical, lumbar, or entire column active vertebral compliance with no differences between conditions. Thus, whilst trunk muscle exercise appears to have minor effect upon IVD height, it may be a candidate approach to mitigate—particularly active—vertebral stability on Earth, and in μg via concurrent SAHC. However, significant variability suggests larger studies including optimization of trunk exercise and SAHC prescription with MRI are warranted—ideally following protracted unloading.
Availability of data and materials
The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.
Advanced Resistive Exercise Device
Activate transversus abdominis
German Aerospace Center
Centre of mass
Short-arm human centrifugation
Short-duration head down bed rest
Brown JW. Crew Height Measurements, the Apollo-Soyuz Test Project Medical Report. Washington, DC: NASA. NASA SP-411; 1977.
Pool-Goudzwaard AL, Belavý DL, Hides JA, et al. Low back pain in microgravity and bed rest studies. Aerosp Med Human Perform. 2015;86:541–7.
Sayson JV, Hargens AR. Pathophysiology of low back pain during exposure to microgravity. Aviat Space Environ Med. 2008;79:365–73.
Belavy DL, Adams M, Brisby H, et al. Disc herniations in astronauts: what causes them, and what does it tell us about herniation on earth? Eur Spine J. 2016;25:144–54.
Chang DG, Healey RM, Snyder AJ, et al. Lumbar spine paraspinal muscle and intervertebral disc height changes in astronauts after long-duration spaceflight on the International Space Station. Spine (Phila Pa 1976). 2016;41:1917–24.
McNamara KP, Greene KA, Moore AM, et al. Lumbopelvic muscle changes following long-duration spaceflight. Front Physiol. 2019;10:627.
Andreoni G, Rigotti C, Baroni G, et al. Quantitative analysis of neutral body posture in prolonged microgravity. Gait Posture. 2000;12:235–42.
Crevecoeur F, McIntyre J, Thonnard JL, et al. Movement stability under uncertain internal models of dynamics. J Neurophysiol. 2010;104:1301–13.
Nicogossian AE, Williams RS, Huntoon CL, et al. Space physiology and medicine: from evidence to practice. 4th ed. New York: Springer; 2016. https://doi.org/10.1007/978-1-4939-6652-3.
Green DA, Scott JPR. Spinal health during unloading and reloading associated with spaceflight. Front Physiol. 2018;8:1126.
Marshburn TH, Hadfield CA, Sargsyan AE, et al. New heights in ultrasound: first report of spinal ultrasound from the international space station. J Emerg Med. 2014;46:61–70.
Garcia KM, Harrison MF, Sargsyan AE, et al. Real-time ultrasound assessment of astronaut spinal anatomy and disorders on the international space station. J Ultrasound Med. 2018;37:987–99.
Ledsome JR, Lessoway V, Susak LE, et al. Diurnal changes in lumbar intervertebral distance, measured using ultrasound. Spine (Phila Pa 1976). 1996;21:1671–5.
Kingsley MI, D’Silva LA, Jennings C, et al. Moderate-intensity running causes intervertebral disc compression in young adults. Med Sci Sports Exerc. 2012;44:2199–204.
Belavý DL, Armbrecht G, Felsenberg D. Incomplete recovery of lumbar intervertebral discs 2 years after 60-day bed rest. Spine (Phila Pa 1976). 2011;37:1245–51.
Häusler M, Hofstetter L, Schweinhardt P, et al. Influence of body position and axial load on spinal stiffness in healthy young adults. Eur Spine J. 2020;29:455–61.
Swanenburg J, Langenfeld A, Easthope CA, et al. Microgravity and hypergravity induced by parabolic flight differently affect lumbar spinal stiffness. Front Physiol. 2020;11:562557. https://doi.org/10.3389/fphys.2020.562557.
Glaus LS, Hofstetter L, Guekos A, et al. In vivo measurements of spinal stiffness according to a stepwise increase of axial load. Eur J Appl Physiol. 2021;121:2277–83.
Stokes IAF, Gardner-Morse M. Spinal stiffness increases with axial load: another stabilizing consequence of muscle action. J Electromyogr Kinesiol. 2003;13:397–402.
Petersen N, Jaekel P, Rosenberger A, et al. Exercise in space: the European Space Agency approach to in-flight exercise countermeasures for long-duration missions on ISS. Extreme Physiol Med. 2016;5:9. https://doi.org/10.1186/s13728-016-0050-4.
Belavý DL, Albracht K, Bruggemann GP, et al. Can exercise positively influence the intervertebral disc? Sports Med. 2016;46:473–85.
Scott JPR, Kramer A, Petersen N, et al. The role of long-term head-down bed rest in understanding inter-individual variation in response to the spaceflight environment: a perspective review. Front Physiol. 2021;12:614619. https://doi.org/10.3389/fphys.2021.614619.
Lang T, van Loon JJWA, Bloomfield S, et al. Towards human exploration of space: the THESEUS review series on muscle and bone research priorities. NPJ Microgravity. 2017;3:8. https://doi.org/10.1038/s41526-017-0013-0.
Demertzi A, van Ombergen A, Tomilovskaya E, et al. Cortical reorganization in an astronaut’s brain after long-duration spaceflight. Brain Struct Funct. 2016;221:2873–6.
Gallo C, Ridolfi L, Scarsoglio S. Cardiovascular deconditioning during long-term spaceflight through multiscale modeling. NPJ Microgravity. 2020;6:27. https://doi.org/10.1038/s41526-020-00117-5.
Hides JA, Lambrecht G, Sexton CT, et al. The effects of exposure to microgravity and reconditioning of the lumbar multifidus and anterolateral abdominal muscles: implications for people with LBP. Spine J. 2021;21:477–91.
Bailey JF, Miller SL, Khieu K, et al. From the international space station to the clinic: how prolonged unloading may disrupt lumbar spine stability. Spine J. 2018;18:7–14.
Scott JPR, Weber T, Green DA. Introduction to the frontiers research topic: optimization of exercise countermeasures for human space flight—lessons from terrestrial physiology and operational considerations. Front Physiol. 2019;10:173. https://doi.org/10.3389/fphys.2019.00173.
Rathinam C, Bridges S, Spokes G, et al. Effects of lycra body suit orthosis on a child with developmental coordination disorder: a case study. J Prosthet Orthot. 2013;25:58–61.
Waldie JM, Newman DJ. A gravity loading countermeasure skinsuit. Acta Astronaut. 2011;68:722–30.
Carvil PA, Attias J, Evetts SN, et al. The effect of the gravity loading countermeasure skinsuit upon movement and strength. J Strength Cond Res. 2017;31:154–61.
Stabler RA, Rosado H, Doyle R, et al. Impact of the Mk VI SkinSuit on skin microbiota of terrestrial volunteers and an International Space Station-bound astronaut. NPJ Microgravity. 2017;3:23. https://doi.org/10.1038/S41526-017-0029-5.
Carvil PA, Jones M, Home D, Ayer R, Osbourne N, Breen A et al. The effect of 4-hour partial axial reloading via the Mk VI SkinSuit upon recumbent lumbar geometry and kinematics after 8-hour hyperbuoyancy flotation. In: 2nd human physiology workshop (Cologne)
Clément G, le Traon AP. Centrifugation as a countermeasure during actual and simulated microgravity: a review. Eur J Appl Physiol. 2004;92:235–48.
Iwasaki KI, Shiozawa T, Kamiya A, et al. Hypergravity exercise against bed rest induced changes in cardiac autonomic control. Eur J Appl Physiol. 2005;94:285–91.
Stenger MB, Evans JM, Patwardhan AR, et al. Artificial gravity training improves orthostatic tolerance in ambulatory men and women. Acta Astronaut. 2007;60:267–72.
Frett T, Green DA, Mulder E, et al. Tolerability of daily intermittent or continuous short-arm centrifugation during 60-day 6° head down bed rest (AGBRESA study). PLoS ONE. 2020;15:e0239228. https://doi.org/10.1371/journal.pone.0239228.
Kramer A, Kümmel J, Dreiner M, et al. Adaptability of a jump movement pattern to a non-constant force field elicited via centrifugation. PLoS ONE. 2020;15:e0230854. https://doi.org/10.1371/journal.pone.0230854.
Attias J, Grassi A, Bosutti A, et al. Head-down tilt bed rest with or without artificial gravity is not associated with motor unit remodeling. Eur J Appl Physiol. 2020;120:2407–15.
Hoffmann F, Rabineau J, Mehrkens D, et al. Cardiac adaptations to 60 day head-down-tilt bed rest deconditioning. Findings from the AGBRESA study. ESC Heart Fail. 2021;8:729–44.
Bertolini G, Straumann D. Moving in a moving world: A review on vestibular motion sickness. Front Neurol. 2016;7:14. https://doi.org/10.3389/fneur.2016.00014.
Goswami N, Evans J, Schneider S, et al. Effects of individualized centrifugation training on orthostatic tolerance in men and women. PLoS ONE. 2015;10:e0125780. https://doi.org/10.1371/journal.pone.0125780.
Frett T, Green DA, Arz M, et al. Motion sickness symptoms during jumping exercise on a short-arm centrifuge. PLoS ONE. 2020;15:e0234361. https://doi.org/10.1371/journal.pone.0234361.
Edinborough L, CP, & GDA. Effect of squat exercise upon lumbar and cervical IVD with 1g and 1.5g at the CoM. (in review).
Saragiotto BT, Maher CG, Yamato TP, et al. Motor control exercise for nonspecific low back pain. Spine (Phila Pa 1976). 2016;41:1284–95.
Coulombe BJ, Games KE, Neil ER, et al. Core stability exercise versus general exercise for chronic low back pain. J Athl Train. 2017;52:71–2.
Owen PJ, Miller CT, Mundell NL, et al. Which specific modes of exercise training are most effective for treating low back pain? Network meta-analysis. Br J Sports Med. 2020;54:1279–87.
Southwell DJ, Hills NF, McLean L, et al. The acute effects of targeted abdominal muscle activation training on spine stability and neuromuscular control. J NeuroEng Rehabil. 2016;13:1–8. https://doi.org/10.1186/s12984-016-0126-9.
Leach RA, Parker PL, Veal PS. PulStar differential compliance spinal instrument: a randomized interexaminer and intraexaminer reliability study. J Manip Physiol Ther. 2003;26:493–501.
Hofstetter L, Häusler M, Wirth B, et al. Instrumented measurement of spinal stiffness: a systematic literature review of reliability. J Manip Physiol Ther. 2018;41:704–11.
Girod B, Rabenstein R, Stenger A. Einführung in die Systemtheorie. Berlin: Springer; 1997. https://doi.org/10.1007/978-3-663-09883-6.
Hofstetter L, Häusler M, Schweinhardt P, et al. Influence of axial load and a 45-degree flexion head position on cervical spinal stiffness in healthy young adults. Front Physiol. 2021;12:2381.
Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. The Lancet. 1986;327:307–10.
Cohen J. Statistical power analysis for the behavioral sciences. New York: Routledge; 1988. https://doi.org/10.4324/9780203771587.
Reilly T, Freeman KA. Effects of loading on spinal shrinkage in males of different age groups. Appl Ergon. 2006;37:305–10.
Kang S, Chang MC, Kim H, Kim J, Jang Y, Park D, Hwang JM. The effects of paraspinal muscle volume on physiological load on the lumbar vertebral column: a finite-element study. Spine. 2021;46(19):E1015–21. https://doi.org/10.1097/BRS.0000000000004014.
Harper KD, Phillips D, Lopez JM, et al. Acute traumatic thoracolumbar paraspinal compartment syndrome: case report. J Neurosurg Spine. 2018;30:140–5.
Shymon S, Hargens AR, Minkoff LA, et al. Body posture and backpack loading: an upright magnetic resonance imaging study of the adult lumbar spine. Eur Spine J. 2014;23:1407–13.
Urban JP, McMullin JF. Swelling pressure of the lumbar intervertebral discs: influence of age, spinal level, composition, and degeneration. Spine (Phila Pa 1976). 1988;13:179–81.
Gooyers CE, McMillan RD, Howarth SJ, et al. The impact of posture and prolonged cyclic compressive loading on vertebral joint mechanics. Spine (Phila Pa 1976). 2012;37:E1023-9. https://doi.org/10.1097/BRS.0b013e318256f9e6.
Wilke HJ, Neef P, Caimi M, et al. New in vivo measurements of pressures in the intervertebral disc in daily life. Spine (Phila Pa 1976). 1999;24:755–62.
Roughley PJ, Alini M, Antoniou J. The role of proteoglycans in aging, degeneration and repair of the intervertebral disc. Biochem Soc Trans. 2002;30:869–74.
Fontes RBV, Baptista JS, Rabbani SR, et al. Normal aging in human lumbar discs: an ultrastructural comparison. PLoS ONE. 2019;14:e0218121. https://doi.org/10.1371/journal.pone.0218121.
Vo NV, Hartman RA, Patil PR, et al. Molecular mechanisms of biological aging in intervertebral discs. J Orthop Res. 2016;34:1289.
Wade KR, Robertson PA, Thambyah A, et al. How healthy discs herniate: a biomechanical and microstructural study investigating the combined effects of compression rate and flexion. Spine (Phila Pa 1976). 2014;39:1018–28.
Murray KJ, le Grande MR, OrtegaDeMues A, et al. Characterisation of the correlation between standing lordosis and degenerative joint disease in the lower lumbar spine in women and men: a radiographic study. BMC Musculoskelet Disord. 2017;18:330. https://doi.org/10.1186/S12891-017-1696-9.
de Martino E, Hides J, Elliott JM, et al. Lumbar muscle atrophy and increased relative intramuscular lipid concentration are not mitigated by daily artificial gravity after 60-day head-down tilt bedrest. J Appl Physiol. 2021. https://doi.org/10.1152/japplphysiol.00990.2020.
Frenken M, Schleich C, Radke KL, Müller-Lutz A, Benedikter C, Franz A, Antoch G, Bittersohl B, Abrar DB, Nebelung S. Imaging of exercise-induced spinal remodeling in elite rowers. J Sci Med Sport. 2021. https://doi.org/10.1016/J.JSAMS.2021.07.015.
Schleich C, Müller-Lutz A, Eichner M, Schmitt B, Matuschke F, Bittersohl B, Zilkens C, Wittsack HJ, Antoch G, Miese F. Glycosaminoglycan chemical exchange saturation transfer of lumbar intervertebral discs in healthy volunteers. Spine. 2016;41(2):146–52. https://doi.org/10.1097/brs.0000000000001144.
Chan ST, Fung PK, Ng NY, Ngan TL, Chong MY, Tang CN, He JF, Zheng YP. Dynamic changes of elasticity, cross-sectional area, and fat infiltration of multifidus at different postures in men with chronic low back pain. Spine J: Off J N Am Spine Soc. 2012;12(5):381–8. https://doi.org/10.1016/j.spinee.2011.12.004.
Creze M, Bedretdinova D, Soubeyrand M, Rocher L, Gennisson JL, Gagey O, Maître X, Bellin MF. Posture-related stiffness mapping of paraspinal muscles. J Anat. 2019;234(6):787–99. https://doi.org/10.1111/joa.12978.
Frett T, Lecheler L, Speer M, Marcos D, Pesta D, Tegtbur U, Jordan J, Green DA. Comparison of trunk muscle exercises in supine position during short arm centrifugation with 1 g at centre of mass and upright in 1 g centrifugation with 1 g at centre of mass and upright in 1 g. Front Physiol. 2022. https://doi.org/10.3389/fphys.2022.955312.
Bergmark A. Stability of the lumbar spine. A study in mechanical engineering. Acta Orthop Scand Suppl. 1989;230:1–54.
Swanenburg J, Meier ML, Langenfeld A, et al. Spinal Stiffness in prone and upright postures during 0–1.8 g induced by parabolic flight. Aerosp Med Hum Perform. 2018;89:563–7.
Olson MW, Li L, Solomonow M. Interaction of viscoelastic tissue compliance with lumbar muscles during passive cyclic flexion-extension. J Electromyogr Kinesiol: Off J Int Soc Electrophysiol Kinesiol. 2009;19(1):30–8. https://doi.org/10.1016/j.jelekin.2007.06.011.
The authors wish to thank all subjects who participated in this study. We also would like to appreciate the Envihab facility at the German Aerospace Center (DLR) in Cologne (Germany) for their support.
Open Access funding enabled and organized by University of Zurich. This study was financed by DLR internal funding. The work of David Marcos was performed with the support of DAAD research grants with contract personal number 91744920.
Ethic approval and consent to participate
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Prior to participating in the study, all participants were informed of the study purpose and details of the study procedure and were requested to give their informed consent was obtained from all the individual participants. The study approved by the North Rhine ethical committee (Number: 6000223393) and registered on 29/09/2020 in the German Clinical Trials Register (DRKS00021750).
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The authors declare no competing interests.
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Marcos-Lorenzo, D., Frett, T., Gil-Martinez, A. et al. Effect of trunk exercise upon lumbar IVD height and vertebral compliance when performed supine with 1 g at the CoM compared to upright in 1 g. BMC Sports Sci Med Rehabil 14, 177 (2022). https://doi.org/10.1186/s13102-022-00575-2
- Artificial gravity