Physiological Impact and Clinical Relevance of Passive Exercise/Movement

Cortical response characteristics of passive, active, and resistance movements: a multi-channel fNRIS study

Objective

This study aimed to explore the impact of exercise training modes on sensory and motor-related cortex excitability using functional near-infrared spectroscopy technology (fNIRS) and reveal specific cortical effects.

Materials and methods

Twenty participants with no known health conditions took part in a study involving passive, active, and resistance tasks facilitated by an upper-limb robot, using a block design. The participants wore functional near-infrared spectroscopy (fNIRS) devices throughout the experiment to monitor changes in cortical blood oxygen levels during the tasks. The fNIRS optode coverage primarily targeted key areas of the brain cortex, including the primary motor cortex (M1), primary somatosensory cortex (S1), supplementary motor area (SMA), and premotor cortex (PMC) on both hemispheres. The study evaluated cortical activation areas, intensity, and lateralization values.

Results

Passive movement primarily activates M1 and part of S1, while active movement mainly activates contralateral M1 and S1. Resistance training activates brain regions in both hemispheres, including contralateral M1, S1, SMA, and PMC, as well as ipsilateral M1, S1, SMA, and PMC. Resistance movement also activates the ipsilateral sensorimotor cortex (S1, SMA, PMC) more than active or passive movement. Active movement has higher contralateral activation in M1 compared to passive movement. Resistance and active movements increase brain activity more than passive movement. Different movements activate various cortical areas equally on both sides, but lateralization differs. The correlation between lateralization of brain regions is significant in the right cortex but not in the left cortex during three movement patterns.

Conclusion

All types of exercise boost motor cortex excitability, but resistance exercise activates both sides of the motor cortex more extensively. The PMC is crucial for intense workouts. The right cortex shows better coordination during motor tasks than the left. fNIRS findings can help determine the length of treatment sessions.

Sitting leg vasculopathy: potential adaptations beyond the endothelium

Increased sitting time, the most common form of sedentary behavior, is an independent risk factor for all-cause and cardiovascular disease mortality; however, the mechanisms linking sitting to cardiovascular risk remain largely elusive. Studies over the last decade have led to the concept that excessive time spent in the sitting position and the ensuing reduction in leg blood flow-induced shear stress cause endothelial dysfunction. This conclusion has been mainly supported by studies using flow-mediated dilation in the lower extremities as the measured outcome. In this review, we summarize evidence from classic studies and more recent ones that collectively support the notion that prolonged sitting-induced leg vascular dysfunction is likely also attributable to changes occurring in vascular smooth muscle cells (VSMCs). Indeed, we provide evidence that prolonged constriction of resistance arteries can lead to modifications in the structural characteristics of the vascular wall, including polymerization of actin filaments in VSMCs and inward remodeling, and that these changes manifest in a time frame that is consistent with the vascular changes observed with prolonged sitting. We expect this review will stimulate future studies with a focus on VSMC cytoskeletal remodeling as a potential target to prevent the detrimental vascular ramifications of too much sitting.

Harnessing Passive Pulsatile Shear Stress for Alzheimer's Disease Prevention and Intervention

 Alzheimer's disease (AD) affects more than 40 million people worldwide and is the leading cause of dementia. This disease is a challenge for both patients and caregivers and puts a significant strain on the global healthcare system. To address this issue, the Lancet Commission recommends focusing on reducing modifiable lifestyle risk factors such as hypertension, diabetes, and physical inactivity. Passive pulsatile shear stress (PPSS) interventions, which use devices like whole-body periodic acceleration, periodic acceleration along the Z-axis (pGz), and the Jogging Device, have shown significant systemic and cellular effects in preclinical and clinical models which address these modifiable risks factors. Based on this, we propose that PPSS could be a potential non-pharmacological and non-invasive preventive or therapeutic strategy for AD. We perform a comprehensive review of the biological basis based on all publications of PPSS using these devices and demonstrate their effects on the various aspects of AD. We draw from this comprehensive analysis to support our hypothesis. We then delve into the possible application of PPSS as an innovative intervention. We discuss how PPSS holds promise in ameliorating hypertension and diabetes while mitigating physical inactivity, potentially offering a holistic approach to AD prevention and management.

Acute orthostatic responses during early mobilisation of patients with acquired brain injury - Innowalk pro versus standing frame

Introduction

Early mobilisation is paramount in the rehabilitation of patients with acquired brain injuries. However, the effectiveness of mobilisation to standing combined with passive leg movement in mitigating orthostatic intolerance remains uncertain. Hence, we investigated whether participants exhibited better tolerance standing in a motorized standing device with passive leg movements, Innowalk Pro, compared to a traditional standing frame.

Methods

17 patients with acquired brain injury (<1 year post-injury) performed two sessions in each standing device on four separate days. Maximum standing time was 30 min, less when symptoms of syncope or volitional exhaustion occurred. Besides total standing time, electromyography of thigh muscles, and changes in mean arterial pressure and heart rate were monitored at rest and during standing.

Results

No significant differences were found in standing time, changes in mean arterial pressure or heart rate between standing in Innowalk Pro and the standing frame. However, participants had significantly more thigh muscle activation (p = 0.006) when standing in Innowalk Pro.

Conclusions

Mobilising participants with a subacute acquired brain injury in a standing frame with motorised passive movements of the lower limbs did, despite higher thigh muscle activation, not lead to better orthostatic tolerance or prolonged standing time compared to a traditional standing frame.

Cardiovascular responses to combined mechanoreflex and metaboreflex activation in healthy adults: effects of sex and low- versus high-hormone phases in females

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.

Pharmacological modulation of adrenergic tone alters the vasodilatory response to passive leg movement in young but not in old adults

The age-related increase in α-adrenergic tone may contribute to decreased leg vascular conductance (LVC) both at rest and during exercise in the old. However, the effect on passive leg movement (PLM)-induced LVC, a measure of vascular function, which is markedly attenuated in this population, is unknown. Thus, in eight young (25 ± 5 yr) and seven old (65 ± 7 yr) subjects, this investigation examined the impact of systemic β-adrenergic blockade (propanalol, PROP) alone, and PROP combined with either α1-adrenergic stimulation (phenylephrine, PE) or α-adrenergic inhibition (phentolamine, PHEN), on PLM-induced vasodilation. LVC, calculated from femoral artery blood flow and pressure, was determined and PLM-induced Δ peak (LVCΔpeak) and total vasodilation (LVCAUC, area under curve) were documented. PROP decreased LVCΔpeak (PROP: 4.8 ± 1.8, Saline: 7.7 ± 2.7 mL·mmHg-1, P < 0.001) and LVCAUC (PROP: 1.1 ± 0.7, Saline: 2.4 ± 1.6 mL·mmHg-1, P = 0.002) in the young, but not in the old (LVCΔpeak, P = 0.931; LVCAUC, P = 0.999). PE reduced baseline LVC (PE: 1.6 ± 0.4, PROP: 2.3 ± 0.4 mL·min-1·mmHg-1, P < 0.01), LVCΔpeak (PE: 3.2 ± 1.3, PROP: 4.8 ± 1.8 mL·min-1·mmHg-1, P = 0.004), and LVCAUC (PE: 0.5 ± 0.4, PROP: 1.1 ± 0.7 mL·mmHg-1, P = 0.011) in the young, but not in the old (baseline LVC, P = 0.199; LVCΔpeak, P = 0.904; LVCAUC, P = 0.823). PHEN increased LVC at rest and throughout PLM in both groups (drug effect: P < 0.05), however LVCΔpeak was only improved in the young (PHEN: 6.4 ± 3.1, PROP: 4.4 ± 1.5 mL·min-1·mmHg-1, P = 0.004), and not in the old (P = 0.904). Furthermore, the magnitude of α-adrenergic modulation (PHEN - PE) of LVCΔpeak was greater in the young compared with the old (Young: 3.35 ± 2.32, Old: 0.40 ± 1.59 mL·min-1·mmHg-1, P = 0.019). Therefore, elevated α-adrenergic tone does not appear to contribute to the attenuated vascular function with age identified by PLM.NEW & NOTEWORTHY Stimulation of α1-adrenergic receptors eliminated age-related differences in passive leg movement (PLM) by decreasing PLM-induced vasodilation in the young. Systemic β-blockade attenuated the central hemodynamic component of the PLM response in young individuals. Inhibition of α-adrenergic receptors did not improve the PLM response in older individuals, though withdrawal of α-adrenergic modulation augmented baseline and maximal vasodilation in both groups. Accordingly, α-adrenergic signaling plays a role in modulating the PLM vasodilatory response in young but not in old adults, and elevated α-adrenergic tone does not appear to contribute to the attenuated vascular function with age identified by PLM.

Cerebral blood flow and immediate and sustained executive function benefits following single bouts of passive and active exercise

Passive exercise occurs when an individual's limbs are moved via an external force and is a modality that increases cerebral blood flow (CBF) and provides an immediate postexercise executive function (EF) benefit. To our knowledge, no work has examined for how long passive exercise benefits EF. Here, healthy young adults (N = 22; 7 female) used a cycle ergometer to complete three 20-min conditions: passive exercise (via mechanically driven flywheel), a traditional light intensity (37 W) "active" exercise condition (i.e., via volitional pedalling) and a non-exercise control condition. An estimate of CBF was obtained via transcranial Doppler ultrasound measurement of middle cerebral artery blood velocity (MCAv) and antisaccades (i.e., saccade mirror-symmetrical to a target) were completed prior to and immediately, 30- and 60-min following each condition to assess EF. Passive and active exercise increased MCAv; however, the increase was larger in the latter condition. In terms of antisaccades, passive and active exercise provided an immediate postexercise reaction time benefit. At the 30-min assessment, the benefit was observed for active but not passive exercise and neither produced a benefit at the 60-min assessment. Thus, passive exercise provided an evanescent EF "boost" and is a finding that may reflect a smaller cortical hemodynamic response.

A Nonrandomized Trial of the Effects of Passive Simulated Jogging on Short-Term Heart Rate Variability in Type 2 Diabetic Subjects

Background

Diabetes mellitus has reached global epidemic proportions, with type 2 diabetes (T2DM) comprising more than 90% of all subjects with diabetes. Cardiovascular autonomic neuropathy (CAN) frequently occurs in T2DM. Heart rate variability (HRV) reflects a neural balance between the sympathetic and parasympathetic autonomic nervous systems (ANS) and a marker of CAN. Reduced HRV has been shown in T2DM and improved by physical activity and exercise. External addition of pulses to the circulation, as accomplished by a passive simulated jogging device (JD), restores HRV in nondiseased sedentary subjects after a single session. We hypothesized that application of JD for a longer period (7 days) might improve HRV in T2DM participants.

Methods

We performed a nonrandomized study on ten T2DM subjects (age range 44-73 yrs) who were recruited and asked to use a physical activity intervention, a passive simulated jogging device (JD) for 7 days. JD moves the feet in a repetitive and alternating manner; the upward movement of the pedal is followed by a downward movement of the forefoot tapping against a semirigid bumper to simulate the tapping of feet against the ground during jogging. Heart rate variability (HRV) analysis was performed using an electrocardiogram in each subject in seated posture on day 1 (baseline, BL), after seven days of JD (JD7), and seven days after discontinuation of JD (Post-JD). Time domain variables were computed, viz., standard deviation of all normal RR intervals (SDNN), standard deviation of the delta of all RR intervals (SDΔNN), and the square root of the mean of the sum of the squares of differences between adjacent RR intervals (RMSSD). Frequency domain measures were determined using a standard Fast Fourier spectral analysis, as well as the parameters of the Poincaré plots (SD1 and SD2).

Results

Seven days of JD significantly increased SDNN, SDΔNN, RMSSD, and both SD1 and SD2 from baseline values. The latter parameters remained increased Post-JD. JD did not modify the frequency domain measures of HRV.

Conclusion

A passive simulated jogging device increased the time domain and Poincaré variables of HRV in T2DM. This intervention provided effortless physical activity as a novel method to harness the beneficial effects of passive physical activity for improving HRV in T2DM subjects.

Non-Invasive Pulsatile Shear Stress Modifies Endothelial Activation; A Narrative Review

The monolayer of cells that line both the heart and the entire vasculature is the endothelial cell (EC). These cells respond to external and internal signals, producing a wide array of primary or secondary messengers involved in coagulation, vascular tone, inflammation, and cell-to-cell signaling. Endothelial cell activation is the process by which EC changes from a quiescent cell phenotype, which maintains cellular integrity, antithrombotic, and anti-inflammatory properties, to a phenotype that is prothrombotic, pro-inflammatory, and permeable, in addition to repair and leukocyte trafficking at the site of injury or infection. Pathological activation of EC leads to increased vascular permeability, thrombosis, and an uncontrolled inflammatory response that leads to endothelial dysfunction. This pathological activation can be observed during ischemia reperfusion injury (IRI) and sepsis. Shear stress (SS) and pulsatile shear stress (PSS) are produced by mechanical frictional forces of blood flow and contraction of the heart, respectively, and are well-known mechanical signals that affect EC function, morphology, and gene expression. PSS promotes EC homeostasis and cardiovascular health. The archetype of inducing PSS is exercise (i.e., jogging, which introduces pulsations to the body as a function of the foot striking the pavement), or mechanical devices which induce external pulsations to the body (Enhanced External Pulsation (EECP), Whole-body vibration (WBV), and Whole-body periodic acceleration (WBPA aka pGz)). The purpose of this narrative review is to focus on the aforementioned noninvasive methods to increase PSS, review how each of these modify specific diseases that have been shown to induce endothelial activation and microcirculatory dysfunction (Ischemia reperfusion injury-myocardial infarction and cardiac arrest and resuscitation), sepsis, and lipopolysaccharide-induced sepsis syndrome (LPS)), and review current evidence and insight into how each may modify endothelial activation and how these may be beneficial in the acute and chronic setting of endothelial activation and microvascular dysfunction.

Hemodynamic analysis of intermittent pneumatic compression combined with hyperthermia after total hip arthroplasty: an experiment on male rabbits

OBJECTIVE

To investigate the effect of intermittent pneumatic compression combined with hyperthermia (IPCH) on the hemodynamic changes in lower limbs of male rabbits and to clarify whether its efficacy is superior to that of intermittent pneumatic compression (IPC) or hyperthermia (HT) alone.

METHODS

Thirty male adult New Zealand white rabbits with a body mass of 2.6±0.3 kg were obtained to establish a model of postoperative hypercoagulable state by simulating left hip surgery. Then they were randomly divided into HT group, IPC group, and IPCH group. Relevant hemodynamic parameters were examined by color Doppler ultrasound before and after treatment. A femoral vein finite element model was established according to fluid mechanics to analyze the blood flow velocity distribution vector, total deformation, equivalent stress of the femoral vein and venous valve.

RESULTS

The heart rate, blood flow per minute, and mean and peak blood velocity of the femoral vein in IPCH group were significantly higher than those in HT and IPC groups (P<0.05). There was no significant difference in venous diameter (P>0.05). The blood flow velocity distribution vector, the total deformation of femoral vein, and the equivalent stress between femoral vein and venous valve in the IPCH group were higher than those in HT and IPC groups, but the total deformation of venous valve was smaller in IPCH group.

CONCLUSIONS

IPCH superimposes the effects of IPC and HT, and can more effectively promote changes in local blood circulation to prevent deep vein thrombosis.

Does Parkinson's disease affect peripheral circulation and vascular function in physically active patients?

Previous studies demonstrated that aging, neurodegeneration, and the level of physical activity are associated with vascular alterations. However, in Parkinson's disease (PD) only cerebral vascular function has been investigated; instead, the contribution of PD on systemic vascular function and skeletal muscle circulation remains a matter of debate. In this study, the hyperemic response during the single passive leg movement test (sPLM), largely nitric oxide dependent, was examined at the level of the common femoral artery with an ultrasound Doppler system to assess systemic vascular function in 10 subjects with PD (PDG), compared with 10 aged-sex and physically active matched healthy elderly (EHG), and 10 physically active young healthy individuals (YHG). Interestingly, femoral blood flow at rest, normalized for the thigh volume, was similar in PDG (64±15 mL min^-1 L^-1), EHG (44±8 mL min^-1 L^-1) and YHG (58±11 mL min^-1 L^-1, all p > 0.05). The sPLM-induced hyperemic response appeared markedly lower in PDG and EHG compared to YHG (8.3±0.1 vs 9.8±0.8 vs 17.3±3.0 mL min^-1 L^-1; p < 0.05) but the difference between PDG and EHG was negligible (p > 0.05). The results of our study indicate that peripheral circulation and vascular function are not reduced in physically active patients with PD, suggesting that these vascular changes could resemble the physiological adjustments of aging, without any impact from the disease.

Long-Term Passive Leg Stretch Improves Systemic Vascular Responsiveness as Much as Single-Leg Exercise Training

PURPOSE

The current study compared the local and systemic vascular responsiveness after small muscle mass endurance training or passive stretching training (PST).

METHODS

Thirty-six sex-matched healthy participants underwent 8-wk single-leg knee extension (SLKE) (n = 12) training or PST (n = 12), or no intervention (control, n = 12). Before and after the intervention, local and systemic vascular responsiveness was assessed by Doppler ultrasound at the femoral (local effect) and brachial artery (systemic effect) during single passive leg movement and brachial flow-mediated dilation (FMD) test, respectively.

RESULTS

After training, delta femoral blood flow (representing the local vascular responsiveness) increased after SLKE and PST by +54 (7)% (effect size, 2.72; P < 0.001) and +20 (2)% (effect size, 2.43; P < 0.001), respectively, albeit with a greater extent in SLKE (post-SLKE vs post-PST: +56 [8]% [effect size, 2.92; P < 0.001]). Interestingly, the %FMD (standing for the systemic effect) increased after SLKE and PST by +12 (2)% (effect size, 0.68; P < 0.001) and +11 (1)% (effect size, 0.83; P < 0.001), respectively, without any between-groups difference (P > 0.05). No changes occurred in control.

CONCLUSIONS

The present findings revealed that both active and passive training modalities induced similar improvements in the brachial artery dilatation capacity, whereas the former was more effective in improving femoral artery blood flow. Passive stretching could be used in people with limited mobility to improve vascular responsiveness both at the local and systemic level and in this latter case has similar effects as small muscle mass endurance training.

Cardiovasomobility: an integrative understanding of how disuse impacts cardiovascular and skeletal muscle health

Cardiovasomobility is a novel concept that encompasses the integration of cardiovascular and skeletal muscle function in health and disease with critical modification by physical activity, or lack thereof. Compelling evidence indicates that physical activity improves health while a sedentary, or inactive, lifestyle accelerates cardiovascular and skeletal muscle dysfunction and hastens disease progression. Identifying causative factors for vascular and skeletal muscle dysfunction, especially in humans, has proven difficult due to the limitations associated with cross-sectional investigations. Therefore, experimental models of physical inactivity and disuse, which mimic hospitalization, injury, and illness, provide important insight into the mechanisms and consequences of vascular and skeletal muscle dysfunction. This review provides an overview of the experimental models of disuse and inactivity and focuses on the integrated responses of the vasculature and skeletal muscle in response to disuse/inactivity. The time course and magnitude of dysfunction evoked by various models of disuse/inactivity are discussed in detail, and evidence in support of the critical roles of mitochondrial function and oxidative stress are presented. Lastly, strategies aimed at preserving vascular and skeletal muscle dysfunction during disuse/inactivity are reviewed. Within the context of cardiovasomobility, experimental manipulation of physical activity provides valuable insight into the mechanisms responsible for vascular and skeletal muscle dysfunction that limit mobility, degrade quality of life, and hasten the onset of disease.

The Effects of Passive Simulated Jogging on Parameters of Explosive Handgrip in Nondiabetics and Type 2 Diabetics: A Single Arm Study

Aims

Type 2 diabetes (T2D) is associated with sarcopenia and decreased muscle strength. Explosive and isometric voluntary handgrip strengths (EHGS and HGS) are frequently utilized methods to ascertain health status and a marker of overall muscle strength. We have previously shown that a portable, motorized device, which produces effortless, rapid stepping in place (passive simulated jogging device (JD)), improves glucose homeostasis. This study quantitatively evaluated the effects of JD in modifying parameters of the modified EHGS curve in T2D and nondiabetic (ND) subjects.

Methods

Twenty-one adult participants (11 ND and 10 T2D) (mean age: 41.3 ± 13.5 yr) performed a modified explosive handgrip strength (EHGS) test on study day 1 followed by daily use of JD (90 min per day) for 7 days. The EHGS was repeated after 3 and 7 days' use of JD (JD3 and JD7) and 3 days after completion of JD (Carryover). EHGS curves were analyzed for the following: maximal peak force value (MAX); rate of force development at 25%,75%, and 90% of maximum force; and maximum force (RFD_25%, RFD_75%, RFD_90%, and RFD_max); time to 90%, 75%, and 25% of maximal force (t₉₀, t₇₅, t₂₅) and time to maximal force (t_max); and the integrated area under the curve for force vs. time until task failure (iAUC_TF); and fatigue resistance times at 50% and 25% of maximal force (FR₅₀ and FR25) and fatigue resistance time to task failure (FR_TF).

Results

At baseline, T2D had lower MAX compared to ND. There were no differences at baseline for force development time or fatigue resistance time between T2D and ND. In both T2D and ND, 7 days of JD increased FR₂₅ and FR_TF and iAUC_TF compared to baseline.

Conclusion

JD for at least 7 days prior to EHGS increased time to task failure (fatigue resistance) and iAUC_TF of the force-time curve. JD is a reasonable intervention to decrease sedentary behavior and improve muscle fatigue resistance under various clinical and nonclinical scenarios. This trial is registered with NCT03550105 (08-06-2018).

Patterns of vascular response immediately after passive mobilization in patients with sepsis: an observational transversal study

Sepsis is a serious organ dysfunction leading to endothelial damage in critical patients. Physiologically, there is an augment of vascular diameter in response to increased vascular blood flow and shear stress stimulus. However, the pattern of vascular response in face of passive mobilization (PM), an early mobilization physical strategy, has not yet been explored in patients with sepsis. To explore patterns of vascular response to PM and associations with clinical and cardiovascular profile in patients with sepsis. Cross-sectional, single-arm study. Thirty-two patients diagnosed with sepsis were enrolled. Vascular response was assessed by flow-mediated dilation (FMD) using brachial artery ultrasound, before and after PM. The PM (to assess the response pattern) and SR (shear rate) were also calculated. PM protocol consisted of knees, hips, wrists, elbows, shoulders, dorsiflexion/plantar flexion movements 3 × 10 repetitions each (15 min). Arterial stiffness was assessed by Sphygmocor®, by analyzing the morphology and pulse wave velocity. Cardiac autonomic modulation (CAM) was assessed by analyzing heart rate variability indexes (mean HR, RMSSD, LF, HF, ApEn, SampEn, DFA). Different vascular responses were observed after PM: (1) increased vascular diameter (responders) (n = 13, %FMD = 11.89 ± 5.64) and (2) reduced vascular diameter (non-responders) (n = 19, %FMD= -7.42 ± 6.44). Responders presented a higher non-linear DFA2 index (p = 0.02). There was a positive association between FMD and DFA (r = 0.529; p = 0.03); FMD and SampEn (r = 0.633; p < 0.01). A negative association was identified between FMD and LF (Hz) (r= -0.680; p < 0.01) and IL-6 (r= -0.469; p = 0.037) and SR and CRP (r= -0.427; p = 0.03).

SPORTS METABOLISM IN IMPROVING NATIONAL FITNESS

ABSTRACT Introduction: Exercise can invigorate the body's metabolism. There are very few people who know how sports promote people's physical and mental health. How to lead people to participate in physical exercise through sports is a question worth considering. Objective: We explore the effects of sports on human metabolism. Methods: The article analyzes athletes’ physical and chemical indicators before and after exercise and during the recovery period. The indicators cover blood routine, urine routine, and blood testosterone content. Results: The blood and urine routines of athletes before and after training are different (P<0.05). After an expressive number of exercises, the urine testosterone content will be different due to the difference in genders (P<0.05). Conclusions: Physical exercise has a very significant impact on human metabolism. The body's hormone levels and metabolism are related to the amount of exercise. Level of evidence II; Therapeutic studies - investigation of treatment results.

Impact of acute antioxidant supplementation on vascular function and autonomic nervous system modulation in young adults with PTSD

Posttraumatic stress disorder (PTSD) has been associated with an increase in risk of cardiovascular disease (CVD). The goal of this study was to determine if peripheral vascular dysfunction, a precursor to CVD, was present in young adults with PTSD, and if an acute antioxidant (AO) supplementation could modify this potential PTSD-induced vascular dysfunction. Thirteen individuals with PTSD were recruited for this investigation and were compared with 35 age- and sex-matched controls (CTRL). The PTSD group participated in two visits, consuming either a placebo (PTSD-PL) or antioxidants (PTSD-AO; vitamins C and E; α-lipoic acid) before their visits, whereas the CTRL subjects only participated in one visit. Upper and lower limb vascular functions were assessed via flow-mediated dilation and passive leg movement technique. Heart rate variability was utilized to assess autonomic nervous system modulation. The PTSD-PL condition, when compared with the CTRL group, reported lower arm and leg microvascular function as well as sympathetic nervous system (SNS) predominance. After acute AO supplementation, arm, but not leg, microvascular function was improved and SNS predominance was lowered to which the prior difference between PTSD group and CTRL was no longer significant. Young individuals with PTSD demonstrated lower arm and leg microvascular function as well as greater SNS predominance when compared with age- and sex-matched controls. Furthermore, this lower vascular/autonomic function was augmented by an acute AO supplementation to the level of the healthy controls, potentially implicating oxidative stress as a contributor to this blunted vascular/autonomic function.

Impact of presymptomatic COVID-19 on vascular and skeletal muscle function: a case study

The impact of COVID-19 has been largely described after symptom development. Although the SARS-CoV-2 virus elevates heart rate (HR) prior to symptom onset, whether this virus evokes other presymptomatic alterations is unknown. This case study details the presymptomatic impact of COVID-19 on vascular and skeletal muscle function in a young woman [24 yr, 173.5 cm, 89 kg, body mass index (BMI): 29.6 kg·m^-2]. Vascular and skeletal muscle function were assessed as part of a separate study with the first and second visits separated by 2 wk. On the evening following the second visit, the participant developed a fever and a rapid antigen test confirmed a positive COVID-19 diagnosis. Compared with the first visit, the participant presented with a markedly elevated HR (∼30 beats/min) and a lower mean blood pressure (∼8 mmHg) at the second visit. Vascular function measured by brachial artery flow-mediated dilation, reactive hyperemia, and passive leg movement were all noticeably attenuated (25%-65%) as was leg blood flow during knee extension exercise. Muscle strength was diminished as was ADP-stimulated respiration (30%), assessed in vitro, whereas there was a 25% increase in the apparent Km. Lastly, an elevation in IL-10 was observed prior to symptom onset. Notably, 2.5 mo after diagnosis symptoms of fatigue and cough were still present. Together, these findings provide unique insight into the physiological responses immediately prior to onset of COVID-19 symptoms; they suggest that SARS-CoV-2 negatively impacts vascular and skeletal muscle function prior to the onset of common symptoms and may set the stage for the widespread sequelae observed following COVID-19 diagnosis.NEW & NOTEWORTHY This unique case study details the impact of SARS-CoV-2 infection on vascular and skeletal muscle function in a young predominantly presymptomatic woman. Prior to COVID-19 diagnosis, substantial reductions in vascular, skeletal muscle, and mitochondrial function were observed along with an elevation in IL-10. This integrative case study indicates that the presymptomatic impact of COVID-19 is widespread and may help elucidate the acute and long-term sequelae of this disease.

Repeated passive mobilization to stimulate vascular function in individuals of advanced age who are chronically bedridden. A randomized controlled trial

BACKGROUND

Vascular dysfunction and associated disorders are major side effects of chronic bed rest, yet passive mobilization as a potential treatment has only been theorized so far. This study investigated the effects of passive mobilization treatment on vascular function in older, chronically bedridden people.

METHODS

The study sample was 45 chronically bedridden people of advanced age (mean age 87 years; 56% female; mean bed rest 4 years) randomly assigned to a treatment (n=23) or a control group (CTRL, n=22). The treatment group received passive mobilization twice daily (30 min, 5 times/week) for 4 weeks. A kinesiologist performed passive mobilization by passive knee flexion/extension at 1 Hz in one leg (treated leg, T-leg vs ctrl-leg). The CTRL group received routine treatment. The primary outcome was changes in peak blood flow (∆Peak) as measured with the single passive leg movement test (sPLM) at the common femoral artery.

RESULTS

∆Peak was increased in both legs in the Treatment group (+90.9 ml/min, p<0.001, in T-leg and +25.7 ml/min, p=0.039 in ctrl-leg). No difference in peak blood flow after routine treatment was found in the CTRL group.

CONCLUSION

Improvement in vascular function after 4 weeks of passive mobilization was recorded in the treatment group. Passive mobilization may be advantageously included in standard clinical practice as an effective strategy to treat vascular dysfunction in persons with severely limited mobility.

The Endothelium as a Therapeutic Target in Diabetes: A Narrative Review and Perspective

Diabetes has reached worldwide epidemic proportions, and threatens to be a significant economic burden to both patients and healthcare systems, and an important driver of cardiovascular mortality and morbidity. Improvement in lifestyle interventions (which includes increase in physical activity via exercise) can reduce diabetes and cardiovascular disease mortality and morbidity. Encouraging a population to increase physical activity and exercise is not a simple feat particularly in individuals with co-morbidities (obesity, heart disease, stroke, peripheral vascular disease, and those with cognitive and physical limitations). Translation of the physiological benefits of exercise within that vulnerable population would be an important step for improving physical activity goals and a stopgap measure to exercise. In large part many of the beneficial effects of exercise are due to the introduction of pulsatile shear stress (PSS) to the vascular endothelium. PSS is a well-known stimulus for endothelial homeostasis, and induction of a myriad of pathways which include vasoreactivity, paracrine/endocrine function, fibrinolysis, inflammation, barrier function, and vessel growth and formation. The endothelial cell mediates the balance between vasoconstriction and relaxation via the major vasodilator endothelial derived nitric oxide (eNO). eNO is critical for vasorelaxation, increasing blood flow, and an important signaling molecule that downregulates the inflammatory cascade. A salient feature of diabetes, is endothelial dysfunction which is characterized by a reduction of the bioavailability of vasodilators, particularly nitric oxide (NO). Cellular derangements in diabetes are also related to dysregulation in Ca²⁺ handling with increased intracellular Ca²⁺overload, and oxidative stress. PSS increases eNO bioavailability, reduces inflammatory phenotype, decreases intracellular Ca²⁺ overload, and increases antioxidant capacity. This narrative review and perspective will outline four methods to non-invasively increase PSS; Exercise (the prototype for increasing PSS), Enhanced External Counterpulsation (EECP), Whole Body Vibration (WBV), Passive Simulated Jogging and its predicate device Whole Body Periodic Acceleration, and will discuss current knowledge on their use in diabetes.

The role of the endothelium in the hyperemic response to passive leg movement: looking beyond nitric oxide

Passive leg movement (PLM) evokes a robust and predominantly nitric oxide (NO)-mediated increase in blood flow that declines with age and disease. Consequently, PLM is becoming increasingly accepted as a sensitive assessment of endothelium-mediated vascular function. However, a substantial PLM-induced hyperemic response is still evoked despite nitric oxide synthase (NOS) inhibition. Therefore, in nine young healthy men (25 ± 4 yr), this investigation aimed to determine whether the combination of two potent endothelium-dependent vasodilators, specifically prostaglandin (PG) and endothelium-derived hyperpolarizing factor (EDHF), account for the remaining hyperemic response to the two variants of PLM, PLM (60 movements) and single PLM (sPLM, 1 movement), when NOS is inhibited. The leg blood flow (LBF, Doppler ultrasound) response to PLM and sPLM following the intra-arterial infusion of N^G-monomethyl-l-arginine (l-NMMA), to inhibit NOS, was compared to the combined inhibition of NOS, cyclooxygenase (COX), and cytochrome P-450 (CYP450) by l-NMMA, ketorolac tromethamine (KET), and fluconazole (FLUC), respectively. NOS inhibition attenuated the overall LBF [area under the curve (LBF_AUC)] response to both PLM (control: 456 ± 194, l-NMMA: 168 ± 127 mL, P < 0.01) and sPLM (control: 185 ± 171, l-NMMA: 62 ± 31 mL, P = 0.03). The combined inhibition of NOS, COX, and CYP450 (i.e., l-NMMA+KET+FLUC) did not further attenuate the hyperemic responses to PLM (LBF_AUC: 271 ± 97 mL, P > 0.05) or sPLM (LBF_AUC: 72 ± 45 mL, P > 0.05). Therefore, PG and EDHF do not collectively contribute to the non-NOS-derived NO-mediated, endothelium-dependent hyperemic response to either PLM or sPLM in healthy young men. These findings add to the mounting evidence and understanding of the vasodilatory pathways assessed by the PLM and sPLM vascular function tests.NEW & NOTEWORTHY Passive leg movement (PLM) evokes a highly nitric oxide (NO)-mediated hyperemic response and may provide a novel evaluation of vascular function. The contributions of endothelium-dependent vasodilatory pathways, beyond NO and including prostaglandins and endothelium-derived hyperpolarizing factor, to the PLM-induced hyperemic response to PLM have not been evaluated. With intra-arterial drug infusion, the combined inhibition of nitric oxide synthase (NOS), cyclooxygenase, and cytochrome P-450 (CYP450) pathways did not further diminish the hyperemic response to PLM compared with NOS inhibition alone.

Vascular dysfunction and oxidative stress caused by acute formaldehyde exposure in female adults

Formaldehyde (FA) is a common, volatile organic compound used in organic preservation with known health effects of eye, nose, and throat irritation linked to oxidative stress and inflammation. Indeed, long-term FA exposure may provoke skin disorders, cancer, and cardiovascular disease. However, the effects of short-term FA exposure on the vasculature have yet to be investigated. We sought to investigate the impact of an acute FA exposure on 1) macrovascular function in the arm (brachial artery flow-mediated dilation, FMD), 2) microvascular function in the arm (brachial artery reactive hyperemia, RH) and leg (common femoral artery, supine passive limb movement, PLM), and 3) circulating markers of oxidative stress (xanthine oxidase, XO; protein carbonyl, PC; and malondialdehyde, MDA) and inflammation (C-reactive protein, CRP). Ten (n = 10) healthy females (23 ± 1 yr) were studied before and immediately after a 90-min FA exposure [(FA): 197 ± 79 ppb] in cadaver dissection laboratories. Brachial artery FMD% decreased following FA exposure (Pre-FA Exp: 9.41 ± 4.21%, Post-FA Exp: 6.74 ± 2.57%; P = 0.043), and FMD/shear decreased following FA exposure (Pre-FA Exp: 0.13 ± 0.07 AU, Post-FA Exp: 0.07 ± 0.03 AU; P = 0.016). The area under the curve for brachial artery RH (Pre-FA Exp: 481 ± 191 ml, Post-FA Exp: 499 ± 165 ml) and common femoral artery PLM (Pre-FA Exp: 139 ± 95 ml, Post-FA Exp: 129 ± 64 ml) were unchanged by FA exposure (P > 0.05). Circulating MDA increased (Pre-FA Exp: 4.8 ± 1.3 µM, Post-FA Exp: 6.3 ± 2.2 µM; P = 0.047) while XO, PC, and CRP were unchanged by FA exposure (P > 0.05). These initial data suggest a short FA exposure can adversely alter vascular function and oxidative stress, influencing cardiovascular health.NEW & NOTEWORTHY This study was the first to investigate the implications of acute formaldehyde (FA) exposure on adult female vascular function in the arms and legs. The main findings of this study were a decrease in conduit vessel function without any alteration to microvascular function following a 90-min FA exposure. Additionally, the oxidative stress marker malondialdehyde increased after FA exposure. Taken together, these results suggest acute FA exposure have deleterious implications for the vasculature and redox balance.Listen to this article's corresponding podcast at https://ajpheart.podbean.com/e/formaldehyde-exposure-decreases-vascular-function/.

Acute effect of passive cycling exercise on serum levels of interleukin-8 and interleukin-10 in mechanically ventilated critically ill patients

Background/aims

A growing body of evidence has demonstrated that early mobilisation is beneficial for patients in the intensive care unit. The aim of this prospective study was to investigate the acute effect of an early passive cycling exercise session on serum interleukin-8 and interleukin-10 levels in critically ill patients.

Methods

A total of 11 haemodynamically stable and deeply sedated (Richmond Agitation and Sedation Scale-4) adult patients within the first 48 hours of mechanical ventilation received a single 20-minute session of passive cycle ergometer. Serum interleukin-8 and interleukin-10 levels were measured at baseline, immediately after the intervention and 60 minutes after the intervention.

Findings

Interleukin-8 levels decreased significantly 60 minutes after the passive cycle ergometer session compared to baseline (P=0.001). The serum levels of interleukin-10 increased immediately after the end of the 20 minutes and at 60 minutes after the intervention (P<0.001).

Conclusions

A single 20-minute session of passive cycle ergometer seems to have a positive effect on the inflammatory response in critically ill patients.

The Effect of Muscle Exercise on Perforators Flow: A Prospective Cohort Study

Background and objectives: The metabolic response after exercise causes a significant increase in the muscle blood flow. While these effects are demonstrated for intra-muscular vessels, there is no evidence about the inter-muscular vessels, such as the septocutaneous perforators supplying the skin after they branch out from the deep source artery. The aim of our prospective study was to quantify the changes in the anterior tibial artery perforators arterial blood flow after mild isotonic exercise in a young and healthy population. Material and Methods: We performed a prospective analysis of 34 patients who were admitted to the Plastic Surgery Department from December 2019 to April 2020. Flow velocities of two previously identified anterior tibial artery perforators were recorded both before and after 10 complete flexion-extensions of the foot. The time to revert to basal flow was measured. We further classified the overmentioned patients based on their level of physical activity. Results: We registered a significant increase in systolic, diastolic and mean blood flow velocities both in proximal and distal anterior tibial artery perforators after exercise. Fitter patients exhibited a higher increase in proximal leg perforators than those who did less than three aerobic workouts a week. The time to return to basal flow ranged from 60 to 90 s. Conclusions: This was the first study to describe the effect of muscular activity on perforators blood flow. Even mild exercise significantly increases the perforator flow. Waiting at least two minutes at rest before performing the Doppler study, thus avoiding involved muscle activation, can notably improve the reliability of the pre-operative planning.

The Vascular Side of Chronic Bed Rest: When a Therapeutic Approach Becomes Deleterious

The interplay between chronic constraint and advanced aging on blood flow, shear-rate, vascular function, nitric oxide (NO)-bioavailability, microcirculation, and vascular inflammation factors is still a matter of debate. Ninety-eight individuals (Young, n = 28, 23 ± 3 yrs; Old, n = 36, 85 ± 7 yrs; Bedridden, n = 34, 88 ± 6 yrs) were included in the study. The bedridden group included old individuals chronically confined to bed (3.8 ± 2.3 yrs). A blood sample was collected and analyzed for plasma nitrate, and vascular inflammatory markers. Hyperemic response (∆peak) during the single passive leg movement (sPLM) test was used to measure vascular function. Skeletal muscle total hemoglobin was measured at the vastus lateralis during the sPLM test, by means of near infrared spectroscopy (NIRS). Bedridden subjects revealed a depletion of plasma nitrates compared with Old (−23.8%) and Young (−31.1%). Blood flow was lower in the Bedridden in comparison to Old (−20.1%) and Young (−31.7%). Bedridden presented lower sPLM ∆peak compared Old (−72.5%) and the Young (−83.3%). ∆peak of NIRS total hemoglobin was lower in the Bedridden compared to that in the Young (−133%). All vascular inflammatory markers except IL-6 were significantly worse in the Bedridden compared to Old and Young. No differences were found between the Old and Young in inflammatory markers. Results of this study confirm that chronic physical constraint induces an exacerbation of vascular disfunction and differential regulation of vascular-related inflammatory markers. The mechanisms involved in these negative adaptations seems to be associated with endothelial dysfunction and consequent diminished NO-bioavailability likely caused by the reduced shear-rate consequential to long-term reduction of physical activity.

Vascular function is related to blood flow during high-intensity, but not low-intensity, knee extension exercise

While vascular function, assessed as the ability of the vasculature to dilate in response to a stimulus, is related to cardiovascular health, its relationship to exercise hyperemia is unclear. This study sought to determine if blood flow during submaximal and maximal exercise is related to vascular function. Nineteen healthy adults completed multiple assessments of vascular function specific to the leg, including passive leg movement (PLM), rapid onset vasodilation (ROV), reactive hyperemia (RH), and flow-mediated dilation (FMD). On a separate day, exercise blood flow (Doppler ultrasound) was assessed in the same leg during various intensities of single-leg, knee-extension (KE) exercise. Vascular function, determined by PLM, ROV, and RH, was related to exercise blood flow at high intensities, including maximum work rate (WRmax) ( r = 0.58–0.77, P < 0.001), but not low intensities, like ~21% WRmax ( r = 0.12–0.34, P = 0.12–0.62). Relationships between multiple indices of vascular function and peak exercise blood flow persisted when controlling for quadriceps mass and exercise work rate ( P < 0.05), indicating vascular function is independently related to the blood flow response to intense exercise. When divided into two groups based upon the magnitude of the PLM response, subjects with a lower PLM response exhibited lower exercise flow at several absolute work rates, as well as lower peak flow ( P < 0.05). In conclusion, leg flow during dynamic exercise is independently correlated with multiple different indices of microvascular function. Thus microvascular function appears to modulate the hyperemic response to high-intensity, but not low-intensity, exercise.

NEW & NOTEWORTHY While substantial evidence indicates that individuals with lower vascular function are at greater risk for cardiovascular disease, with many redundant vasodilator pathways present during exercise, it has been unclear if low vascular function actually impacts blood flow during exercise. This study provides evidence that vascular function, assessed by multiple noninvasive methods, is related to the blood flow response to high-intensity leg exercise in healthy young adults. Importantly, healthy young adults with lower levels of vascular function, particularly microvascular function, exhibit lower blood flow during high-intensity, and maximal knee extension exercise. Thus it appears that in addition to increasing one’s risk of cardiovascular disease, lower vascular function is also related to a blunted blood flow response during high-intensity exercise.

Assessment of resistance vessel function in human skeletal muscle: guidelines for experimental design, Doppler ultrasound, and pharmacology

The introduction of duplex Doppler ultrasound almost half a century ago signified a revolutionary advance in the ability to assess limb blood flow in humans. It is now widely used to assess blood flow under a variety of experimental conditions to study skeletal muscle resistance vessel function. Despite its pervasive adoption, there is substantial variability between studies in relation to experimental protocols, procedures for data analysis, and interpretation of findings. This guideline results from a collegial discussion among physiologists and pharmacologists, with the goal of providing general as well as specific recommendations regarding the conduct of human studies involving Doppler ultrasound-based measures of resistance vessel function in skeletal muscle. Indeed, the focus is on methods used to assess resistance vessel function and not upstream conduit artery function (i.e., macrovasculature), which has been expertly reviewed elsewhere. In particular, we address topics related to experimental design, data collection, and signal processing as well as review common procedures used to assess resistance vessel function, including postocclusive reactive hyperemia, passive limb movement, acute single limb exercise, and pharmacological interventions.