Vascular Function Improvements After Chronic Passive Stretching

NCT ID: NCT04271241

Last Updated: 2020-02-17

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 39 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2019-01-07
• Study Completion Date: 2020-02-07

Brief Summary

Acutely, during different bouts of passive stretching (PS), blood flow (Q ̇) and shear rate ( ) in the feeding artery of the stretched muscles increases during the first two elongations and then it reduces during the following bouts. This hyperemic response during the first two elongations is mediated by the local release of vasoactive molecules (e.g. nitric oxide, NO). This phenomenon disappears during the following elongations due to the NO and other vasoactive molecule depletion. The relaxation phase between stretching bouts, instead, is always characterized by hyperemia as results of stretch-induced peripheral resistances decrease. Whether chronic PS administration may influence vascular function is still a matter of investigation. The hypothesis is that repetitive PS-induced Q ̇ and changes may be an enough stimulus to provoke increments in NO bioavailability, thus improving vasomotor response.

Detailed Description

Vasomotor response is an important marker of cardiovascular health and has been related to cardiovascular co-morbidity. An alteration of vasomotor response, indeed, often precedes an increase in arterial stiffness. By improving and/or maintaining this vascular function, therefore, plays a pivotal role in the prevention of cardiovascular disease. The overall control of the vasomotor response and, in turn, of blood flow distribution in the human body is regulated by two main mechanisms: a systemic control given by the sympathetic nervous system that acts on the arterial smooth muscle fibers causing vasoconstriction, and a local action of vasoactive molecules released by the endothelial cells, such as nitric oxide (NO), leading to vasodilation.

Recent studies report that acute passive stretching (PS), a well-established practice in rehabilitation and sport environments to increase range of motion, may influence the vasomotor response. Specifically, PS provokes two conflicting events: (i) a vasoconstriction with blood flow reduction in the feeding artery of the stretched muscle, triggered by the systemic increase in sympathetic neural tone due to the PS-induced stress on the muscle mechano- and metaboreceptors, and (ii) a vasodilation and subsequent increase in blood flow in the feeding artery due to the prevalence of local vasoactive factors release as a result of the stretch-induced stress applied to the vessel wall, which overwhelms the systemic sympathetic activation. Interestingly, throughout several stretch-shortening cycles, the first acute hyperemic response to stretch described above seems to progressively attenuate until its disappearance during the subsequent stretching cycles, possibly due to NO and other vasoactive molecules depletion.

The shortening phase in between two stretch bouts, instead, is always characterized by hyperemia due to a reduction in the peripheral vascular resistance after the stretch-induced vessels deformation. Possible explanation of these phenomena involves the shear rate, which is the frictional or drag force acting on the inner lumen of the vessels that can trigger a chain of reactions, possibly leading to higher endothelial NO-synthase activity. Continuous and repetitive increases in shear rate induced by PS have been observed to act as vascular training to modulate endothelium remodeling and to improve vasomotor response.

Interestingly, during an acute PS administration, a reduction in blood flow during stretching was described in the contralateral, no-stretched limb. Such a reduction was promptly recovered during the shortening phase. The authors suggested that this occurrence was induced by a systemic sympathetic-mediated vasoconstriction, which was activated by the stretch-induced mechanoreflex.

However, whether chronic PS administration may also affect the vasomotor response in the feeding artery of the contralateral muscle, which was not directly involved in the stretching maneuver, is still an open question.

Together with the changes in local control mechanisms, also possible PS-induced changes in the systemic autonomic control of blood flow has been reported (i.e., reduction in blood pressure and aortic wave reflection magnitude, although its effectiveness remains a matter of debate With this in mind, this study aimed to investigate the effect of PS on the vasomotor response and the stiffness of the arteries directly involved (i.e., femoral and popliteal arteries) and not directly involved (i.e., contralateral femoral and popliteal arteries and brachial artery) with the maneuver applied on the plantar flexors, knee extensor and hip flexor muscles. To this purpose, vasomotor response and arterial stiffness were assessed by Doppler ultrasounds and applanation tonometry, respectively, before and after 12 weeks of PS administration. Hypothesis has been made that repetitive PS bouts, with consequent changes in blood flow and shear rate, may be an effective stimulus to (i) enhance local vasoactive molecules bioavailability in the arteries involved with PS; and (ii) induce a systemic re-modulation of the sympathetic autonomic activity, thus improving arterial compliance and vasomotor response even in those districts not directly involved with PS.

Conditions

Vasodilation; Vasoconstriction; Stretch; Sympathetic; Imbalance

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: SINGLE

Study Groups

Control (Ctrl)

Ctrl group di not undergo any training

Group Type: NO_INTERVENTION

No interventions assigned to this group

PS bilateral limbs (PSBil)

PSBil underwent 12 weeks of passive stretching on both the lower limbs

Group Type: EXPERIMENTAL

Passive stretching (PS) training

Intervention Type: OTHER

PSBil and PSMono underwent 12 weeks of PS training, 3 sessions per week (36 sessions in total). In PSBil, each session lasted 40 min and included two maneuvers for both the knee extensor and plantar flexor muscles with the following protocol: 45 s elongation and 15 s recovery in the resting position, all the cycle repeated for five times 7. In PSMono, exercises were performed only on the right limb and each session had a duration of 20 min. Ctrl did not underwent any PS exercise throughout the study. To promote participants' compliance, daily classes were held at different day time (morning and afternoon) at the University Sports Centre gym. Each class was supervised by an expert operator, which monitored the attendance, the correct exercise execution and the intensity exerted during the exercise (80% of the point of discomfort). The participants not attending at least the 80% of classes were excluded from the study, and a new participant was recruited to substitute the drop out.

PS monolateral limb, stretched limb (PSMonoSL)

PSMonoSL underwent 12 weeks of passive stretching on just one lower limb (SL). Outcomes form this group were obtained from the stretched

Group Type: EXPERIMENTAL

Passive stretching (PS) training

Intervention Type: OTHER

PSBil and PSMono underwent 12 weeks of PS training, 3 sessions per week (36 sessions in total). In PSBil, each session lasted 40 min and included two maneuvers for both the knee extensor and plantar flexor muscles with the following protocol: 45 s elongation and 15 s recovery in the resting position, all the cycle repeated for five times 7. In PSMono, exercises were performed only on the right limb and each session had a duration of 20 min. Ctrl did not underwent any PS exercise throughout the study. To promote participants' compliance, daily classes were held at different day time (morning and afternoon) at the University Sports Centre gym. Each class was supervised by an expert operator, which monitored the attendance, the correct exercise execution and the intensity exerted during the exercise (80% of the point of discomfort). The participants not attending at least the 80% of classes were excluded from the study, and a new participant was recruited to substitute the drop out.

PS monolateral limb, contralateral limb PSMonoCL

PSMonoCL involved the same participants as in PSMonoSL. Outcomes form this group were obtained from the contralateral not stretched limb (CL). Data from this limb helped in identify possible PS-induced crossover effects in the vasomotor response.

Group Type: EXPERIMENTAL

Passive stretching (PS) training

Intervention Type: OTHER

PSBil and PSMono underwent 12 weeks of PS training, 3 sessions per week (36 sessions in total). In PSBil, each session lasted 40 min and included two maneuvers for both the knee extensor and plantar flexor muscles with the following protocol: 45 s elongation and 15 s recovery in the resting position, all the cycle repeated for five times 7. In PSMono, exercises were performed only on the right limb and each session had a duration of 20 min. Ctrl did not underwent any PS exercise throughout the study. To promote participants' compliance, daily classes were held at different day time (morning and afternoon) at the University Sports Centre gym. Each class was supervised by an expert operator, which monitored the attendance, the correct exercise execution and the intensity exerted during the exercise (80% of the point of discomfort). The participants not attending at least the 80% of classes were excluded from the study, and a new participant was recruited to substitute the drop out.

Interventions

Passive stretching (PS) training

PSBil and PSMono underwent 12 weeks of PS training, 3 sessions per week (36 sessions in total). In PSBil, each session lasted 40 min and included two maneuvers for both the knee extensor and plantar flexor muscles with the following protocol: 45 s elongation and 15 s recovery in the resting position, all the cycle repeated for five times 7. In PSMono, exercises were performed only on the right limb and each session had a duration of 20 min. Ctrl did not underwent any PS exercise throughout the study. To promote participants' compliance, daily classes were held at different day time (morning and afternoon) at the University Sports Centre gym. Each class was supervised by an expert operator, which monitored the attendance, the correct exercise execution and the intensity exerted during the exercise (80% of the point of discomfort). The participants not attending at least the 80% of classes were excluded from the study, and a new participant was recruited to substitute the drop out.

Intervention Type: OTHER

Eligibility Criteria

Inclusion Criteria

• None

Exclusion Criteria

• presence of neurological, vascular and musculoskeletal impairments at the lower and upper limbs level;
• being on pharmacological therapy related to either neural and/or vascular response, including hormonal contraceptives and oral supplements;
• being a current or former smoker;
• having an irregular menstrual cycle (26 to 35 days) up to three months before the beginning of the study,
• presenting contraindication for joint mobilization;
• being regularly involved in PS program.

• Minimum Eligible Age: 18 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

University of Milan

OTHER

Sponsor Role: lead

Responsible Party

Emilano Cè

Associate Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Emiliano Cè, PhD

Role: PRINCIPAL_INVESTIGATOR

University of Milan

Locations

Department of Biomedical Science for Health

Milan, , Italy

Countries

Italy

Other Identifiers

Stretching vasomotor response

Identifier Type: -

Identifier Source: org_study_id