Comparison of trunk muscle exercises in supine position during short arm centrifugation with 1 g at centre of mass and upright in 1 g

Abstract

Spaceflight is associated with reduced antigravitational muscle activity, which results in trunk muscle atrophy and may contribute to post-flight postural and spinal instability. Exercise in artificial gravity (AG) performed via short-arm human centrifugation (SAHC) is a promising multi-organ countermeasure, especially to mitigate microgravity-induced postural muscle atrophy. Here, we compared trunk muscular activity (mm. rectus abdominis, ext. obliques and multifidi), cardiovascular response and tolerability of trunk muscle exercises performed during centrifugation with 1 g at individual center of mass on a SAHC against standard upright exercising. We recorded heart rate, blood pressure, surface trunk muscle activity, motion sickness and rating of perceived exertion (BORG) of 12 participants (8 male/4 female, 34 ± 7 years, 178.4 ± 8.2 cm, 72.1 ± 9.6 kg). Heart rate was significantly increased (p < 0.001) during exercises without differences in conditions. Systolic blood pressure was higher (p < 0.001) during centrifugation with a delayed rise during exercises in upright condition. Diastolic blood pressure was lower in upright (p = 0.018) compared to counter-clockwise but not to clockwise centrifugation. Target muscle activation were comparable between conditions, although activity of multifidi was lower (clockwise: p = 0.003, counter-clockwise: p < 0.001) and rectus abdominis were higher (clockwise: p = 0.0023, counter-clockwise: < 0.001) during centrifugation in one exercise type. No sessions were terminated, BORG scoring reflected a relevant training intensity and no significant increase in motion sickness was reported during centrifugation. Thus, exercising trunk muscles during centrifugation generates comparable targeted muscular and heart rate response and appears to be well tolerated. Differences in blood pressure were relatively minor and not indicative of haemodynamic challenge. SAHC-based muscle training is a candidate to reduce microgravity-induced inter-vertebral disc pathology and trunk muscle atrophy. However, further optimization is required prior to performance of a training study for individuals with trunk muscle atrophy/dysfunction.

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

“…In fact, reductions in active vertebral compliance are consistent with those reported when donning a backpack [16] or via axial loading [18], and during a recent parabolic flight where vertebral compliance reductions were observed during hypergravity (~ 1.8 g) when standing 'upright' [17]. Our set of exercises were determined to target activation of vertebral stabilizers [72], therefore their activation is likely to redistribute load [73], potentially decreasing vertebral stiffness [74]. However, this hypothesis needs further research as a significant inter-subject variability in vertebral compliance measures has been observed [50], a Marcos-Lorenzo et al BMC Sports Science, Medicine and Rehabilitation (2022) 14:177 potential confound given the relatively low sample size of the current study.…”

Effects of a microgravity SkinSuit on lumbar geometry and kinematics

“…Twenty-two males were recruited to the study. Two withdrew before the second imaging session, both due to unrelated health problems, leaving twenty participants (mean age 25.5, range 21-36, mean BMI 23.7, range [19][20][21][22][23][24][25][26][27][28][29] who completed all parts of the study. No adverse effects were reported, and all participants reported feeling comfortable in the Skin-Suit.…”

“…Furthermore, without knowledge of the underlying pathophysiology, determination and/or development of candidate countermeasures is difficult. However, artificial gravity via short-arm centrifugation [20], and more recently exercise during centrifugation [21] in addition to donning axial loading garments such as SkinSuits [22,23] have been suggested to promote spinal control [24] whilst exercises performed in the ISS [25][26][27] and sometimes incorporating an axial compression harness [25] may generate transient loading [4]. Of these, axial loading SkinSuits appear to be the most easily implementable for ISS missions and beyond [28] where operational constraints will be more severe [29].…”

Centrifugal rowing as a strategy to mitigate cardiovascular and muscular deconditioning in prolonged immobilization and spaceflight – a pilot trial

“…However, head movement during short arm centrifugation is associated with disorientation and motion sickness (16) and orthostatic intolerance can occur (17). Nevertheless, with moderate gravity load (e.g., 1g at center of mass) and congruent head and body motion, moderate movement during concurrent plyometric exercises (18) and trunk exercise (19,20) is well-tolerated. Hemodynamic responses to these exercises seem largely similar to those on Earth, albeit at relatively low intensities.…”