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Background: Beneficial effects of whole-body vibration (WBV) on brain and musculoskeletal health in mice have been demonstrated, but underlying mechanisms remain relatively unrevealed. WBV improves attention and memory performance in mice, putatively through stimulation of the cholinergic system. Here, we investigated the effects of WBV on the septo-hippocampal cholinergic system. Methods: Young C57BL/6 mice (8 weeks old) were subjected to 10 min WBV/day (mechanical vibration: 30 Hz; ~0.1-µm peak-to-peak displacement), 5X/week for 5 weeks. In Experiment 1, choline acetyltransferase (ChAT)-immunoreactivity in the septum and hippocampus was analyzed either 2 or 24 h after the last WBV session. Pseudo-WBV-treated mice (same handling procedure as WBV, but no vibrations) served as controls. In Experiment 2, the longitudinal profile of ChAT-immunoreactivity was analyzed in the hippocampus after 1, 2, 3, 4, or 5 weeks of WBV. In addition, synaptophysin immunostaining was performed at either 2 and 5 weeks of WBV. Mice housed 1/cage during the entire experiment served as controls. The balance-beam test was used to monitor the functional impact of WBV. In Experiment 3, a Y-maze reference-memory test was performed after 5 weeks of WBV to obtain a functional cognitive outcome measure of WBV. Pseudo-WBV treated mice served as controls. Results: In Experiment 1, ChAT-immunoreactivity was significantly enhanced after the last WBV session of the 5-week period. This was found in the septum, Cornu Ammonis 1 (CA1), CA3, and dentate gyrus, and was dependent on layer and time-point (2 or 24 h). Experiment 2 revealed that, ChAT-immunoreactivity was lower after 2 weeks of WBV, whereas it was significantly higher after 5 weeks (similar to in Experiment 1). Immunostaining for synaptophysin, a marker for synaptic density, was also significantly higher after 5 weeks of WBV, but not significantly lower after 2 weeks, as was ChAT. WBV-treated groups performed significantly better than did controls on the balance beam from week 3 onwards. Experiment 3 showed that WBV-treated mice had better spatial-reference memory performance in the Y-maze test than did pseudo-WBV controls. Conclusions: Our results indicate that WBV stimulates the septo-hippocampal cholinergic system in a gradual and dynamic way that may contribute to improved spatial-memory performance. This finding suggests that WBV, by upregulation of the septo-hippocampal cholinergic system, may be considered a valuable therapeutic strategy to enhance brain functions in aging, neurodegenerative, and other brain diseases. [ABSTRACT FROM AUTHOR]

Whole-body vibration (WBV) therapy is a way of passive exercise in which subjects are exposed to mild and well-controlled mechanical vibrations through a vibrating platform. For a long time, studies have focused on the effects and applications of WBV to enhance musculoskeletal performance in athletes and patients suffering from musculoskeletal disorders. Recent evidence points toward the positive effect of WBV on the brain and its therapeutic potential in brain disorders. Research being done in the field gradually reveals cellular and molecular mechanisms underlying WBV affecting the body and brain. Particularly, the influence of WBV on immune and brain function is a growing field that warrants an up-to-date and integrated review. Immune function is closely intertwined with brain functioning and plays a significant role in various brain disorders. Dysregulation of the immune response is linked to conditions such as neuroinflammation, neurodegenerative diseases, and mood disorders, highlighting the crucial connection between the immune system and the brain. This review aims to explore the impact of WBV on the cellular and molecular pathways involved in immune and brain functions. Understanding the effects of WBV at a cellular and molecular level will aid in optimizing WBV protocols to improve its therapeutic potential for brain disorders. [ABSTRACT FROM AUTHOR]

Whole-body vibration (WBV) therapy is a way of passive exercise in which subjects are exposed to mild and well-controlled mechanical vibrations through a vibrating platform. For a long time, studies have focused on the effects and applications of WBV to enhance musculoskeletal performance in athletes and patients suffering from musculoskeletal disorders. Recent evidence points toward the positive effect of WBV on the brain and its therapeutic potential in brain disorders. Research being done in the field gradually reveals cellular and molecular mechanisms underlying WBV affecting the body and brain. Particularly, the influence of WBV on immune and brain function is a growing field that warrants an up-to-date and integrated review. Immune function is closely intertwined with brain functioning and plays a significant role in various brain disorders. Dysregulation of the immune response is linked to conditions such as neuroinflammation, neurodegenerative diseases, and mood disorders, highlighting the crucial connection between the immune system and the brain. This review aims to explore the impact of WBV on the cellular and molecular pathways involved in immune and brain functions. Understanding the effects of WBV at a cellular and molecular level will aid in optimizing WBV protocols to improve its therapeutic potential for brain disorders.

Background: Beneficial effects of whole-body vibration (WBV) on brain and musculoskeletal health in mice have been demonstrated, but underlying mechanisms remain relatively unrevealed. WBV improves attention and memory performance in mice, putatively through stimulation of the cholinergic system. Here, we investigated the effects of WBV on the septo-hippocampal cholinergic system. Methods: Young C57BL/6 mice (8 weeks old) were subjected to 10 min WBV/day (mechanical vibration: 30 Hz; ~0.1-μm peak-to-peak displacement), 5X/week for 5 weeks. In Experiment 1, choline acetyltransferase (ChAT)-immunoreactivity in the septum and hippocampus was analyzed either 2 or 24 h after the last WBV session. Pseudo-WBV-treated mice (same handling procedure as WBV, but no vibrations) served as controls. In Experiment 2, the longitudinal profile of ChAT-immunoreactivity was analyzed in the hippocampus after 1, 2, 3, 4, or 5 weeks of WBV. In addition, synaptophysin immunostaining was performed at either 2 and 5 weeks of WBV. Mice housed 1/cage during the entire experiment served as controls. The balance-beam test was used to monitor the functional impact of WBV. In Experiment 3, a Y-maze reference-memory test was performed after 5 weeks of WBV to obtain a functional cognitive outcome measure of WBV. Pseudo-WBV treated mice served as controls. Results: In Experiment 1, ChAT-immunoreactivity was significantly enhanced after the last WBV session of the 5-week period. This was found in the septum, Cornu Ammonis 1 (CA1), CA3, and dentate gyrus, and was dependent on layer and time-point (2 or 24 h). Experiment 2 revealed that, ChAT-immunoreactivity was lower after 2 weeks of WBV, whereas it was significantly higher after 5 weeks (similar to in Experiment 1). Immunostaining for synaptophysin, a marker for synaptic density, was also significantly higher after 5 weeks of WBV, but not significantly lower after 2 weeks, as was ChAT. WBV-treated groups performed significantly better than did controls on the balance beam from week 3 onwards. Experiment 3 showed that WBV-treated mice had better spatial-reference memory performance in the Y-maze test than did pseudo-WBV controls. Conclusions: Our results indicate that WBV stimulates the septo-hippocampal cholinergic system in a gradual and dynamic way that may contribute to improved spatial-memory performance. This finding suggests that WBV, by upregulation of the septo-hippocampal cholinergic system, may be considered a valuable therapeutic strategy to enhance brain functions in aging, neurodegenerative, and other brain diseases.

Background: Postmenopausal women are more prone to develop muscle weakness, which is strongly associated with impairment of mitochondrial function in skeletal muscle. This study aimed to examine the impact of a passive exercise modality, whole-body vibration training (WBVT), on muscle mitochondrial function in ovariectomized (OVX) mice, in comparison with 17β-estradiol (E2) replacement. Methods: Female C57BL/6J mice were assigned to four groups: sham operation control group (Sham), ovariectomized group (OVX), OVX with E2 supplement group (OVX+E), and OVX with WBVT group (OVX+W). The estrous cycle, body weight, body composition, and muscle strength of the mice were monitored after the operation. Serum E2 level was assessed by enzyme-linked immunosorbent assay (ELISA). The ATP levels were determined using a luciferase-catalyzed bioluminescence assay. The activity of mitochondrial respiration chain complexes was evaluated using high-resolution respirometry (O2K). Expression levels of oxidative phosphorylation (OXPHOS), peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), and mitochondrial transcription factor A (TFAM) were detected using western blotting. Results: We observed decreased muscle strength and impaired mitochondrial function in the skeletal muscle of OVX mice. The vibration training alleviated these impairments as much as the E2 supplement. In addition, the vibration training was superior to the ovariectomy and the estradiol replacement regarding the protein expression of PGC-1α and TFAM. Conclusion: WBVT improves the OVX-induced decline in muscle strength and impairment of mitochondrial function in the skeletal muscle. This passive exercise strategy may be useful as an alternative to E2 replacement for preventing menopausal muscular weakness. Further studies are needed to understand the effects of WBVT on various physiological systems, and precautions should be taken when implementing it in patient treatment. [ABSTRACT FROM AUTHOR]

Whole body vibration (WBV) is a form of passive exercise that offers an alternative physical training to aged individuals with limitations in their physical and mental capabilities. The aim of the present study was to explore the therapeutic potential of five weeks of WBV on anxiety-like behaviors as well as learning and memory abilities in senescent thirty months old rats. Animals were exposed to 5 min vibration twice per day, five times per week during the five consecutive weeks. Pseudo WBV treated animals served as controls. After five weeks of WBV treatment, animals were tested for anxiety-like behavior by the open field test and for spatial and object memory functions by the novel and spatial object recognition tests, respectively. As a result, anxiety-like and exploratory behaviors were significantly improved in the WBV treated group compared to the pseudo WBV group. Furthermore, WBV treatment increased discrimination performance in both spatial and object memory function testing. These results indicate that WBV treatment in thirty months old rats seems to have comparable beneficial effects on age-related emotional and cognitive performance as what has been reported in younger age groups.

Abstract Background Alzheimer’s disease (AD) is the core cause of dementia in elderly populations. One of the main hallmarks of AD is extracellular amyloid beta (Aβ) accumulation (APP-pathology) associated with glial-mediated neuroinflammation. Whole-Body Vibration (WBV) is a passive form of exercise, but its effects on AD pathology are still unknown. Methods Five months old male J20 mice (n = 26) and their wild type (WT) littermates (n = 24) were used to investigate the effect of WBV on amyloid pathology and the healthy brain. Both J20 and WT mice underwent WBV on a vibration platform or pseudo vibration treatment. The vibration intervention consisted of 2 WBV sessions of 10 min per day, five days per week for five consecutive weeks. After five weeks of WBV, the balance beam test was used to assess motor performance. Brain tissue was collected to quantify Aβ deposition and immunomarkers of astrocytes and microglia. Results J20 mice have a limited number of plaques at this relatively young age. Amyloid plaque load was not affected by WBV. Microglia activation based on IBA1-immunostaining was significantly increased in the J20 animals compared to the WT littermates, whereas CD68 expression was not significantly altered. WBV treatment was effective to ameliorate microglia activation based on morphology in both J20 and WT animals in the Dentate Gyrus, but not so in the other subregions. Furthermore, GFAP expression based on coverage was reduced in J20 pseudo-treated mice compared to the WT littermates and it was significantly reserved in the J20 WBV vs. pseudo-treated animals. Further, only for the WT animals a tendency of improved motor performance was observed in the WBV group compared to the pseudo vibration group. Conclusion In accordance with the literature, we detected an early plaque load, reduced GFAP expression and increased microglia activity in J20 mice at the age of ~ 6 months. Our findings indicate that WBV has beneficial effects on the early progression of brain pathology. WBV restored, above all, the morphology of GFAP positive astrocytes to the WT level that could be considered the non-pathological and hence “healthy” level. Next experiments need to be performed to determine whether WBV is also affective in J20 mice of older age or other AD mouse models.

Background: Alzheimer's disease (AD) is the core cause of dementia in elderly populations. One of the main hallmarks of AD is extracellular amyloid beta (Aβ) accumulation (APP-pathology) associated with glial-mediated neuroinflammation. Whole-Body Vibration (WBV) is a passive form of exercise, but its effects on AD pathology are still unknown. Methods: Five months old male J20 mice (n = 26) and their wild type (WT) littermates (n = 24) were used to investigate the effect of WBV on amyloid pathology and the healthy brain. Both J20 and WT mice underwent WBV on a vibration platform or pseudo vibration treatment. The vibration intervention consisted of 2 WBV sessions of 10 min per day, five days per week for five consecutive weeks. After five weeks of WBV, the balance beam test was used to assess motor performance. Brain tissue was collected to quantify Aβ deposition and immunomarkers of astrocytes and microglia. Results: J20 mice have a limited number of plaques at this relatively young age. Amyloid plaque load was not affected by WBV. Microglia activation based on IBA1-immunostaining was significantly increased in the J20 animals compared to the WT littermates, whereas CD68 expression was not significantly altered. WBV treatment was effective to ameliorate microglia activation based on morphology in both J20 and WT animals in the Dentate Gyrus, but not so in the other subregions. Furthermore, GFAP expression based on coverage was reduced in J20 pseudo-treated mice compared to the WT littermates and it was significantly reserved in the J20 WBV vs. pseudo-treated animals. Further, only for the WT animals a tendency of improved motor performance was observed in the WBV group compared to the pseudo vibration group. Conclusion: In accordance with the literature, we detected an early plaque load, reduced GFAP expression and increased microglia activity in J20 mice at the age of ~ 6 months. Our findings indicate that WBV has beneficial effects on the early progression of brain pathology. WBV restored, above all, the morphology of GFAP positive astrocytes to the WT level that could be considered the non-pathological and hence "healthy" level. Next experiments need to be performed to determine whether WBV is also affective in J20 mice of older age or other AD mouse models. [ABSTRACT FROM AUTHOR]

Introduction: Mechanically ventilated critically ill subjects are often given strict bed rest and sometimes completely immobilized because of the severity of their illness and the administration of drugs such as sedatives. Active mobilization is not possible in subjects under deep sedation and unable to follow commands. In this scenario, passive therapy is an interesting alternative. Objective: This study aimed to evaluate the effectiveness of passive exercises on arterial blood gases in mechanically ventilated subjects from intensive care units. Methods: Five mechanically ventilated subjects participated in the study. The subjects were assigned to one study group, which received passive exercises for one daily session, including ten repetitions in three series per articulation. Arterial Blood Gases were assessed by arterial blood sample analysis with the Stat Profile Prime Plus device. Results: The results revealed a marked improvement in arterial blood gas exchange as compared to baseline reflecting an increase in FIO2- the inspiratory fraction of oxygen, pO2- partial pressure of oxygen, and pO2/FIO2- the ratio between the partial pressure of oxygen and the inspiratory fraction of oxygen and a decrease in CO2- carbon dioxide. Conclusions: The passive exercise showed a slight trend of beneficial changes at the cellular level in mechanically ventilated subjects since the first day after admission, which may indicate a reduction in the inspiratory fraction of oxygen and at the end, extubation of subjects. [ABSTRACT FROM AUTHOR]

Purpose: The enhanced external counterpulsation (EECP), a kind of passive exercise, is a novel non-invasive therapy used to improve peripheral perfusion in patients with coronary artery disease (CAD). However, whether frequency-domain characteristics of peripheral hemodynamics may benefit from passive exercise needs to be verified.Methods: We recruited 21 patients with CAD and 21 healthy controls in this study. Ultrasonic blood flow velocity spectrum in left carotid (LC) and right carotid (RC) common arteries, and right brachial (RB) and right femoral (RF) arteries was monitored using an ultrasonic Doppler. Frequency-domain characteristics before, during, and after passive exercise were extracted from ultrasonic spectrum images. The first and second peak amplitudes/frequencies (y1, y2, x1, x2) and power spectral energy ratio (PSER) in the 0–2.05 Hz/0.87 Hz (p5, p6) were calculated by fast Fourier transform and power spectrum density analysis.Results: For the amplitude and frequency characteristics of the spectrum, y1 in the LC of patients with CAD was significantly decreased during exercise (p = 0.036), whereas, y2 was significantly decreased immediately after passive exercise (p = 0.038). Besides those, y1 only in the RC and RB of controls was significantly decreased during exercise. Immediately after exercise, y2 in the LC of control was significantly lower than at the baseline (p = 0.014). For the energy ratio characteristics of the spectrum, there was an opposite response in the two groups that p6 was significantly reduced and elevated in the LC of controls and in the RB of patients with CAD during exercise (both p < 0.05).Conclusions: Passive exercise reduces amplitude and frequency characteristics of carotid arteries, while there was an opposite response of energy ratio characteristics in the LC and RB arteries to passive exercise between CAD patients and controls. Additionally, energy ratio characteristics of spectrum in the brachial artery were markedly elevated in CAD patients during passive exercise. Moreover, passive exercise only reduces amplitude characteristics of LC artery in the control group.

Background: In-bed passive cycling is considered a safe and feasible early mobilization technique in intensive care unit (ICU) patients who are unable to exercise actively. However, the impact of varying intensity of passive cycling on perfusion and function of ischemia-prone organs is unknown. In this study, we assessed the impact of a graded passive cycling protocol on hemodynamics, cerebral blood flow, and cardiac function in a cohort of septic ICU patients.Methods: In consecutive patients presenting with sepsis, we measured global hemodynamic indices, middle cerebral artery velocity (MCAv), and cardiac function in response to a graded increase in passive cycling cadence. Using 5-min stages, we increased cadence from 5 to 55 RPM in increments of 10 RPM, preceded and followed by 5 min baseline and recovery periods at 0 RPM. The mean values obtained during the last 2 min of each stage were compared within and between subjects for all metrics using repeated-measures ANOVA.Results: Ten septic patients (six males) completed the protocol. Across patients, there was a 5.2% reduction in MCAv from baseline at cycling cadences of 25–45 RPM with a dose-dependent decrease of MCAv of > 10% in four of the 10 patients enrolled. There was a 16% increase in total peripheral resistance from baseline at peak cadence of 55 RPMs and no changes in any other measured hemodynamic parameters. Patient responses to passive cycling varied between patients in terms of magnitude, direction of change, and the cycling cadence at which these changes occurred.Conclusions: In septic patients, graded passive cycling is associated with dose-dependent decreases in cerebral blood flow, increases in total peripheral resistance, and either improvement or worsening of left ventricular function. The magnitude and cadence threshold of these responses vary between patients. Future studies should establish whether these changes are associated with clinical outcomes, including cognitive impairment, vasopressor use, and functional outcomes.

Purpose: Passive in-bed cycling (PC) can provide the benefits of early mobilization to critically ill patients who are unable to exercise actively. However, the effect of PC on global hemodynamics and perfusion of ischemia-prone organs, such as the brain and the heart, is unknown. Therefore, prior to studying the effects of PC in hemodynamically fragile critically ill patients, we characterized hemodynamic, brain blood flow, and cardiac function responses to a graded increase in PC cadence in a cohort of healthy subjects.Methods: We measured global hemodynamic indices, middle cerebral artery velocity (MCAv), and cardiac function in response to a graded increase in PC cadence. Using 5 min stages, we increased cadence from 5 to 55 RPM in increments of 10 RPM, preceded and followed by 5 min baseline and recovery periods at 0 RPM. The mean values obtained during the last 2 min of each stage were compared within and between subjects for all metrics using repeated measures ANOVA.Results: 11 healthy subjects (6 females) completed the protocol. Between subjects, there was no change in MCAv, cardiac function or hemodynamics with the graded increase in cadence with one exception. There was a 7% increase in mean arterial pressure (MAP) from baseline to 55RPM, that persisted through the recovery period. Across subjects, responses were heterogeneous, with some experiencing reduction in cardiac index, cerebral blood flow (CBF) and cardiac function, especially at higher cadence.Conclusions: In healthy adults, increasing PC cadence increased MAP in all subjects, while cardiac index, CBF, and cardiac function responses varied between subjects. Application of PC to critically ill patients must therefore consider individual variation in responses and tailor the PC to the patient. It is essential to further characterize these responses to PC in the critically ill prior to wide-scale clinical implementation.

Whole body vibration (WBV) is a form of passive exercise that offers an alternative physical training to aged individuals with limitations in their physical and mental capabilities. The aim of the present study was to explore the therapeutic potential of five weeks of WBV on anxiety-like behaviors as well as learning and memory abilities in senescent thirty months old rats. Animals were exposed to 5 min vibration twice per day, five times per week during the five consecutive weeks. Pseudo WBV treated animals served as controls. After five weeks of WBV treatment, animals were tested for anxiety-like behavior by the open field test and for spatial and object memory functions by the novel and spatial object recognition tests, respectively. As a result, anxiety-like and exploratory behaviors were significantly improved in the WBV treated group compared to the pseudo WBV group. Furthermore, WBV treatment increased discrimination performance in both spatial and object memory function testing. These results indicate that WBV treatment in thirty months old rats seems to have comparable beneficial effects on age-related emotional and cognitive performance as what has been reported in younger age groups., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

[Purpose] This study aimed to investigate cardiovascular responses, including heart rate (HR) and heart rate variability (HRV), to various hyperlactatemia-passive exercise interactions. [Participants and Methods] Nine healthy male participants performed upper limb passive cycling movement, and their HR and HRV were assessed while their blood lactate levels were manipulated by sustained handgrip exercise at control, 15% maximum voluntary contraction (MVC), and 30% MVC, followed by postexercise circulatory occlusion. [Results] HR and root mean squared standard difference (rMSSD) of HRV response remained constant at all blood lactate levels during passive exercise (HR: control, 75.8 ± 3.4 bpm; 15% MVC, 76.9 ± 2.7 bpm; and 30% MVC, 77.0 ± 3.7 bpm; rMSSD: control, 33.2 ± 6.9 ms; 15% MVC, 36.3 ± 7.3 ms; and 30% MVC, 37.3 ± 8.9 ms). [Conclusion] Manipulating metaboreflex activation did not significantly alter HR or HRV during passive exercise. These results suggest that, in healthy participants, the interactions between mechanical and metabolic stimuli do not affect HR and HRV responses, implying that passive exercise may be safely implemented., Competing Interests: None., (2024©by the Society of Physical Therapy Science. Published by IPEC Inc.)

Background: Postmenopausal women are more prone to develop muscle weakness, which is strongly associated with impairment of mitochondrial function in skeletal muscle. This study aimed to examine the impact of a passive exercise modality, whole-body vibration training (WBVT), on muscle mitochondrial function in ovariectomized (OVX) mice, in comparison with 17β-estradiol (E 2 ) replacement., Methods: Female C57BL/6J mice were assigned to four groups: sham operation control group (Sham), ovariectomized group (OVX), OVX with E 2 supplement group (OVX+E), and OVX with WBVT group (OVX+W). The estrous cycle, body weight, body composition, and muscle strength of the mice were monitored after the operation. Serum E 2 level was assessed by enzyme-linked immunosorbent assay (ELISA). The ATP levels were determined using a luciferase-catalyzed bioluminescence assay. The activity of mitochondrial respiration chain complexes was evaluated using high-resolution respirometry (O2K). Expression levels of oxidative phosphorylation (OXPHOS), peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), and mitochondrial transcription factor A (TFAM) were detected using western blotting., Results: We observed decreased muscle strength and impaired mitochondrial function in the skeletal muscle of OVX mice. The vibration training alleviated these impairments as much as the E 2 supplement. In addition, the vibration training was superior to the ovariectomy and the estradiol replacement regarding the protein expression of PGC-1α and TFAM., Conclusion: WBVT improves the OVX-induced decline in muscle strength and impairment of mitochondrial function in the skeletal muscle. This passive exercise strategy may be useful as an alternative to E 2 replacement for preventing menopausal muscular weakness. Further studies are needed to understand the effects of WBVT on various physiological systems, and precautions should be taken when implementing it in patient treatment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Hu, Fang, Tian, Wang, Tian, Yu, Li, Yang and Shi.)

Females generally have smaller blood pressure (BP) responses to isolated muscle mechanoreflex and metaboreflex activation compared with males, which may explain sex differences in BP responses to voluntary exercise. The mechanoreflex may be sensitized during exercise, but whether mechanoreflex-metaboreflex interactions differ by sex or variations in sex hormones remains unknown. Thirty-one young healthy subjects (females, n = 16) performed unilateral passive cycling (mechanoreflex), active cycling (40% peak Watts), postexercise circulatory occlusion (PECO; metaboreflex), and passive cycling combined with PECO (combined mechanoreflex and metaboreflex activation). Beat-to-beat BP, heart rate, inactive leg vascular conductance, and active leg muscle oxygenation were measured. Ten females underwent exploratory testing during low- and high-hormone phases of their self-reported menstrual cycle or oral contraceptive use. Systolic BP and heart rate responses did not differ between sexes during active cycling [Δ30 ± 9 vs. 29 ± 11 mmHg (males vs. females), P = 0.9; Δ33 ± 8 vs. 35 ± 6 beats/min, P = 0.4] or passive cycling with PECO (Δ26 ± 11 vs. 21 ± 10 mmHg, P = 0.3; Δ14 ± 7 vs. 18 ± 15 beats/min, P = 0.3). Passive cycling with PECO revealed additive, not synergistic, effects for systolic BP [males: Δ23 ± 14 vs. 26 ± 11 mmHg (sum of isolated passive cycling and PECO vs. combined activation); females: Δ26 ± 11 vs. 21 ± 12 mmHg, interaction P = 0.05]. Results were consistent in subset analyses with sex differences in active cycling BP ( P > 0.1) and exploratory analyses of hormone phase ( P > 0.4). Despite a lack of statistical equivalence, no differences in cardiovascular responses were found during combined mechanoreflex-metaboreflex activation between sexes or hormone levels. These results provide preliminary data regarding the involvement of muscle mechanoreflex-metaboreflex interactions in mediating sex differences in voluntary exercise BP responses. NEW & NOTEWORTHY The muscle mechanoreflex may be sensitized by metabolites during exercise. We show that cardiovascular responses to combined mechanoreflex (passive cycling) and metaboreflex (postexercise circulatory occlusion) activation are primarily additive and do not differ between males and females, or across variations in sex hormones in females. Our findings provide new insight into the contributions of muscle mechanoreflex-metaboreflex interactions as a cause for prior reports that females have smaller blood pressure responses to voluntary exercise.

Astronauts are severely affected by spaceflight-induced bone loss. Mechanical stimulation through exercise inhibits bone resorption and improves bone formation. Exercise and vibration can prevent the degeneration of the musculoskeletal system in tail-suspended rats, and long-term exercise stress will affect endocrine and immune systems that are prone to fatigue. However, the mechanisms through which exercise and vibration affect the endocrine system remain unknown. This study mainly aimed to investigate the changes in the contents of endocrine axis-related hormones and the effects of local vibration and passive exercise on hypothalamic-pituitary-adrenal (HPA) axis-related hormones in tail-suspended rats. A total of 32 Sprague-Dawley rats were randomly distributed into four groups (n = 8 per group): tail suspension (TS), TS + 35Hz vibration, TS + passive exercise, and control. The rats were placed on a passive exercise and local vibration regimen for 21 days. On day 22 of the experiment, the contents of corticotrophin-releasing hormone, adrenocorticotropic hormone, cortisol, and 5-hydroxytryptamine in the rats were quantified with kits in accordance with the manufacturer’s instructions. Histomorphometry was applied to evaluate histological changes in the hypothalamus. Results showed that 35Hz local vibration cannot cause rats to remain in a stressed state and that it might not inhibit the function of the HPA axis. Therefore, we speculate that this local vibration intensity can protect the function of the HPA axis and helps tail-suspended rats to transition from stressed to adaptive state. [ABSTRACT FROM AUTHOR]

The contribution of central command to the peripheral vasoconstrictor response during exercise has been investigated using primarily handgrip exercise. The purpose of the present study was to compare muscle sympathetic nerve activity (MSNA) responses during passive (involuntary) and active (voluntary) zero-load cycling to gain insights into the effects of central command on sympathetic outflow during dynamic exercise. Hemodynamic measurements and contralateral leg MSNA (microneurography) data were collected in 18 young healthy participants at rest and during 2 min of passive and active zero-load one-legged cycling. Arterial baroreflex control of MSNA burst occurrence and burst area were calculated separately in the time domain. Blood pressure and stroke volume increased during exercise (P < 0.0001) but were not different between passive and active cycling (P > 0.05). In contrast, heart rate, cardiac output, and total vascular conductance were greater during the first and second minute of active cycling (P < 0.001). MSNA burst frequency and incidence decreased during passive and active cycling (P < 0.0001), but no differences were detected between exercise modes (P > 0.05). Reductions in total MSNA were attenuated during the first (P < 0.0001) and second (P = 0.0004) minute of active compared with passive cycling, in concert with increased MSNA burst amplitude (P = 0.02 and P = 0.005, respectively). The sensitivity of arterial baroreflex control of MSNA burst occurrence was lower during active than passive cycling (P = 0.01), while control of MSNA burst strength was unchanged (P > 0.05). These results suggest that central feedforward mechanisms are involved primarily in modulating the strength, but not the occurrence, of a sympathetic burst during lowintensity dynamic leg exercise. [ABSTRACT FROM AUTHOR]

Spaceflight induced bone loss is seriously affecting astronauts. Mechanical stimulation from exercise has been shown to restrain bone resorption as well as improve bone formation. Current exercise countermeasures in space cannot prevent it completely. Active exercise may convert to passive exercise in some ways because of the loss of gravity stimulus and inertia of exercise equipment. The aim of this study was to compare the efficacy of passive exercise or/and local vibration on counteracting the deterioration of the musculoskeletal system, including bone, muscle and tendons in tail-suspended rats. We hypothesized that local vibration could enhance the efficacy of passive exercise on countering bone loss. 40 Sprague Dawley rats were randomly distributed into five groups (n = 8, each): tail-suspension (TS), TS+35 Hz vibration (TSV), TS + passive exercise (TSP), TS + passive exercise coupled with 35 Hz vibration (TSPV) and control (CON). Passive exercise or/and local vibration was performed for 21 days. On day 0 and 21, bone mineral density (BMD) was observed by dual energy X-ray absorptiometry (DXA), and trabecular microstructure was evaluated by microcomputer tomography (μCT) analysis in vivo. Mechanical properties of tibia and tendon were determined by a mechanical testing system. Soleus and bone ash weight was tested by an electronic balance. Results showed that the passive exercise could not prevent the decrease of trabecular BMD, microstructure and bone ash weight induced by TS, whereas vibration and passive exercise coupled with local vibration (PV) could. Biomechanical properties of the tibia and tendon in TSPV group significantly increased compared with TS group. In summary, PV in this study was the best method in preventing weightlessness-induced bone loss. Consistent with our hypothesis, local vibration partly enhanced the effect of passive exercise. Furthermore, this study will be useful in improving countermeasure for astronauts, but also for the rehabilitation of disused or aged osteoporosis. [ABSTRACT FROM AUTHOR]

Background: Physiotherapy is an important part of treatment after severe brain injuries and stroke, but its effect on intracranial and systemic hemodynamics is minimally investigated. Therefore, the aim of this study was to assess the effects of an early bedside cycle exercise on intracranial and systemic hemodynamics in critically ill patients when admitted to a neurointensive care unit (NICU).Methods: Twenty critically ill patients suffering from brain injuries or stroke were included in this study performed in the NICU at Sahlgrenska University Hospital. One early implemented exercise session was performed using a bedside cycle ergometer for 20 min. Intracranial and hemodynamic variables were measured two times before, three times during, and two times after the bedside cycling exercise. Analyzed variables were intracranial pressure (ICP), cerebral perfusion pressure (CPP), mean arterial blood pressure (MAP), heart rate (HR), peripheral oxygen saturation (SpO2), cardiac output (CO), stroke volume (SV), and stroke volume variation (SVV). The cycling intervention was conducted within 7 ± 5 days after admission to the NICU.Results: Cycle exercise increased MAP (p = 0.029) and SV (p = 0.003) significantly. After exercise CO, SV, MAP, and CPP decreased significantly, while no changes in HR, SVV, SpO2, or ICP were noted when compared to values obtained during exercise. There were no differences in data obtained before versus after exercise.Conclusion: Early implemented exercise with a bedside cycle ergometer, for patients with severe brain injuries or stroke when admitted to a NICU, is considered to be a clinically safe procedure. [ABSTRACT FROM AUTHOR]

To overcome the shortcomings of traditional manual motion device for laboratory animals, a passive training device for laboratory animals is made. It uses cylindrical metal screen cage as main part, micro motor reducer as power device; a controller controls motor speed and rotation direction, and transforms electrical energy into mechanical energy ; timer is used to as record and fix movement time . The speed of the intelligent electric rotating cage can be controlled gradually in 4-6 rpm to overcome the shortcomings of the traditional manual rotating cage, such as time-consuming, energy-consuming, uneven rotating speed and uneven motion intensity. By putting rats in the intelligent electric rotating cage to rotate, the results show that rats can move at a uniform speed in the cage device. When the amount of movement reaches the goal, the rats can stop automatically. The passive motion and the amount of movement of the experimental animals in the rotating cage can be recorded completely. Through the manufacture and application of the device, it is proved that the intelligent experimental animal motion rotating cage device can better satisfy the experimental movement. Research requirements of physical movement. [ABSTRACT FROM AUTHOR]

Background The complex pathophysiology of heart failure (HF) creates a challenging paradigm to differentiate the role of central and peripheral hemodynamic dysfunction during conventional exercise. Adopting a novel reductionist approach with potential clinical relevance, we studied the central and peripheral contributors to both continuous and single passive leg movement (PLM)-induced hyperemia in 14 HF patients with reduced ejection fraction (HFrEF) and 13 controls. Methods Heart rate (HR), stroke volume (SV), cardiac output (CO), mean arterial pressure (MAP), and femoral artery blood flow (FBF) were recorded during PLM. Results The FBF response (area under the curve; AUC) to 60 s of continuous PLM was attenuated in the HFrEF (25 ± 15 ml AUC) compared to controls (199 ± 34 ml AUC) as were peak changes from baseline for FBF, leg vascular conductance (LVC), CO, and HR. During single PLM, increases in CO and HR were smaller and no longer different between groups, supporting the use of this modality to assess groups with disparate central hemodynamics. Interestingly, single PLM-induced hyperemia, likely predominantly driven by flow-mediated vasodilation due to minimal vessel deformation, was essentially nonexistent in the HFrEF (- 9 ± 10 ml AUC) in contrast to the controls (43 ± 25 ml AUC). Conclusions These data fail to support a HFrEF-associated exaggeration in the mechanoreceptor driven component of the exercise pressor response. In fact, by exhibiting limited central hemodynamic responses compared to the controls, the observed attenuation in movement-induced FBF in HFrEF appears largely due to peripheral vascular dysfunction, particularly flow-mediated vasodilation. [ABSTRACT FROM AUTHOR]

Passive range of motion exercise is a very common physical therapy treatment for patients admitted to an intensive care unit. However is the knowledge scarce regarding its impact on blood circulation in the extremities. The objective of this study was therefore to investigate the effect of passive range of motion on arterial peripheral leg blood flow velocity (BFV) and vascular resistance. A cross-sectional consecutive study of twelve patients admitted to an intensive care unit and twelve healthy age- and gender-matched controls was conducted. Passive range of motion was performed in one leg by a physical therapist. Blood flow velocities and resistance index in the common femoral artery (CFA), blood pressure and heart rate were measured before, directly after and at rest after passive range of motion. No changes were seen in BFV or resistance index in the patient group or the control group. No changes were found in blood pressure or heart rate in the patient group. In the control group, changes were found in systolic and mean blood pressure, with a higher pressure before passive range of motion. The controls had lower BFV and higher resistance index than the patients when comparing the groups. The conclusion of this study including twelve patients is that passive range of motion does not alter BFV or resistance index in the CFA in comatose and/or sedated critically ill patients. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the cardiocirculatory response during passive walking-like leg movement in the standing posture (PWM) PWM in healthy young men. It states that subjects were grouped in a sitting and quiet standing positions to determine baseline levels. Results show that systolic arterial blood pressure (SAP) reduces during the sitting baseline period. It is inferred that PWM is effective for inhibiting cardiocirculatory responses to orthostatic stress.

The effects of cardiopulmonary baroreceptors and muscle mechanoreceptors stimulation on cardiac baroreflex sensitivity (BRS), and heart rate variability (HRV) were evaluated by measuring continuously and non-invasively systolic blood pressure (SBP) and pulse interval (PI) during upright and supine passive cycling. BRS and HRV were evaluated with the cross-correlation method ( xBRS) and in the frequency domain, respectively. At rest, the shift from upright to supine posture enhanced xBRS from 16.4±12.1 to 23.4±12.9 ms/mmHg, and the high frequency (HF, 0.15–0.4 Hz) power of HRV from 48.9±18.6 to 55.1±14.7 normalized units (NU), while it attenuated the low-frequency (LF, 0.04–0.15 Hz) power from 51.1±18.6 to 44.9±14.7 NU ( P<0.05), respectively. During both upright and supine passive exercise, xBRS and the HF power were attenuated (10.0±8.0 and 12.5±9.0 ms/mmHg; 41.1±21.2 and 41.5±12.7 NU, respectively; P<0.05) and the LF power increased (58.8±21.2 and 58.5±12.7 NU, P<0.05), compared with rest. The effect of mechanoreflex activation overrides that of the cardiopulmonary baroreceptors loading resulting in decreased cardiac vagal outflow and reduced BRS during supine passive exercise. [ABSTRACT FROM AUTHOR]

We report a case of an individual with cervical spinal cord injury who showed a unique blood pressure response during passive standing and passive walking-like leg movement, i.e., hypertension with standing and hypotension with leg movement. [ABSTRACT FROM AUTHOR]

Abstract: Passive limb movement (PLM) in humans induces a phasic hyperpnea, but the underlying physiological mechanisms remain unclear. We asked whether PLM in anesthetized rats would produce a similar phasic hyperpnea associated with an augmented ventilatory response to CO2 that is dependent on sciatic afferents. The animals underwent 5min threshold PLM, 3min hypercapnia (5% CO2), and their combination (CO2 exposure at the end of 2nd min of 5-min PLM) before and after bilateral transection of the sciatic nerves. We found that a threshold PLM evoked a phasic hyperpnea, similar to that denoted in humans, and an augmented response to CO2. Both responses were greatly diminished by sciatic nerve transection. Moreover, similar responses were also evoked by electrically stimulating the central end of the transected sciatic nerve. Our findings suggest an ability of the sciatic afferents to augment the response to CO2 that likely contributes to the PLM-induced hyperpnea. [Copyright &y& Elsevier]

The primary aim of the study was to examine substrate metabolism during combined passive and active exercise in individuals with spinal cord injury (SCI). Nine men and women with SCI (mean age 40.6 +/- 3.4 years) completed two trials of submaximal exercise 1 week apart. Two maintained a complete injury and seven had an incomplete injury. Level of injury ranged from thoracic (T4-T6 and T10) to cervical (four C5-C6 and three C6-C7 injuries). During two bouts separated by 1 week, subjects completed two 30 min sessions of active lower-body and passive upper-body exercise, during which heart rate (HR) and gas exchange data were continuously assessed. One-way analysis of variance with repeated measures was used to examine differences in all variables over time. Results demonstrated significant increases (P < 0.05) in HR and oxygen uptake (VO(2)) from rest to exercise. Respiratory exchange ratio (RER) significantly increased (P < 0.05) during exercise from 0.85 +/- 0.02 at rest to 0.95 +/- 0.01 at the highest cadence, reflecting increasing reliance on carbohydrate from 50.0 to 83.0% of energy metabolism. Data demonstrate a large reliance on carbohydrate utilization during 30 min of exercise in persons with SCI, with reduced contribution of lipid as exercise intensity was increased. Strategies to reduce carbohydrate utilization and increase lipid oxidation in this population should be addressed. [ABSTRACT FROM AUTHOR]

To examine blood pressure responses during passive walking-like exercise in the standing posture (PWE) in spinal cord-injured (SCI) humans. Twelve motor-complete SCI individuals (cervical level 6 to thoracic level 12, ASIA grade: A or B) and twelve able-bodied controls (CON) participated in this study. SCI individuals were divided into a group with injury level at or above thoracic (T) 6 (HSCI, n = 7) and a group with injury level at or below T10 (LSCI, n = 5). Subjects carried out 6-minute quiet standing and then 12-minute PWE at 1 Hz using a gait training apparatus that enables subjects to stand and move their legs passively. Mean arterial blood pressures (MAPs) at standing in HSCI, LSCI and CON were 69 ± 5, 83 ± 4 and 93 ± 2 mmHg, respectively. MAP changed significantly during PWE only in HSCI and CON, increasing to 88 ± 4 ( P < 0.001) and 98 ± 1 mmHg ( P < 0.01), respectively. The former group showed a larger increase in MAP ( P < 0.001). Spinal sympathetic reflexes can be induced in a region isolated from the brainstem in response to a stimulus originating below the level of the spinal cord injury, and the magnitude of increase in blood pressure is greater in SCI individuals with lesion level at or above T6 due to loss of supraspinal control of the major sympathetic outflow. This central mechanism may be one of the reasons why greater pressor response to PWE was observed in HSCI. [ABSTRACT FROM AUTHOR]