Respiratory muscle training positively affects vasomotor response in young healthy women

Vasomotor response is related to the capacity of the vessel to maintain vascular tone within a narrow range. Two main control mechanisms are involved: the autonomic control of the sympathetic neural drive (global control) and the endothelial smooth cells capacity to respond to mechanical stress by releasing vasoactive factors (peripheral control). The aim of this study was to evaluate the effects of respiratory muscle training (RMT) on vasomotor response, assessed by flow-mediated dilation (FMD) and heart rate variability, in young healthy females. The hypothesis was that RMT could enhance the balance between sympa- thetic and parasympathetic neural drive and reduce vessel shear stress. Thus, twenty-four women were randomly assigned to either RMT or SHAM group. Maximal inspiratory mouth pressure and maximum voluntary ventilation were utilized to assess the effectiveness of the RMT program, which consisted of three sessions of isocapnic hyperventilation/ week for eight weeks, (twenty-four training sessions). Heart rate variability assessed autonomic bal- ance, a global factor regulating the vasomotor response. Endothelial function was deter- mined by measuring brachial artery vasodilation normalized by shear rate (%FMD/SR). After RMT, but not SHAM, maximal inspiratory mouth pressure and maximum voluntary ventilation increased significantly (+31% and +16%, respectively). Changes in heart rate variability were negligible in both groups. Only RMT exhibited a significant increase in % FMD/SR (+45%; p\u3c0.05). These data suggest a positive effect of RMT on vasomotor response that may be due to a reduction in arterial shear stress, and not through modulation of sympatho-vagal balance

Central and peripheral responses to static and dynamic stretch of skeletal muscle: mechano- and metaboreflex implications

Passive static stretching (SS), circulatory cuff occlusion (CCO), and the combination of both (SS + CCO) have been used to investigate the mechano- and metaboreflex, respectively. However, the effects of dynamic stretching (DS) alone or in combination with CCO (DS + CCO) on the same reflexes have never been explored. The aim of the study was to compare central and peripheral hemodynamic responses to DS, SS, DS + CCO, and SS + CCO. In 10 participants, femoral blood flow (FBF), heart rate (HR), cardiac output (CO), and mean arterial pressure (MAP) were assessed during DS and SS of the quadriceps muscle with and without CCO. Blood lactate concentration [La(-)] in the lower limb undergoing CCO was also measured. FBF increased significantly in DS and SS by 365 \ub1 98 and 377 \ub1 102 ml/min, respectively. Compared with baseline, hyperemia was negligible during DS + CCO and SS + CCO (+11 \ub1 98 and +5 \ub1 87 ml/min, respectively). DS generated a significant, sustained increase in HR and CO ( 3c40s), while SS induced a blunted and delayed cardioacceleration ( 3c20 s). After CCO, [La(-)] in the lower limb increased by 135%. Changes in HR and CO during DS + CCO and SS + CCO were similar to DS and SS alone. MAP decreased significantly by 3c5% during DS and SS, did not change in DS + CCO, and increased by 4% in SS + CCO. The present data indicate a reduced mechanoreflex response to SS compared with DS (i.e., different HR and CO changes). SS evoked a hyperemia similar to DS. The similar central hemodynamics recorded during stretching and [La(-)] accumulation suggest a marginal interaction between mechano- and metaboreflex

Respiratory muscle training positively affects vasomotor response in young healthy women.

Vasomotor response is related to the capacity of the vessel to maintain vascular tone within a narrow range. Two main control mechanisms are involved: the autonomic control of the sympathetic neural drive (global control) and the endothelial smooth cells capacity to respond to mechanical stress by releasing vasoactive factors (peripheral control). The aim of this study was to evaluate the effects of respiratory muscle training (RMT) on vasomotor response, assessed by flow-mediated dilation (FMD) and heart rate variability, in young healthy females. The hypothesis was that RMT could enhance the balance between sympathetic and parasympathetic neural drive and reduce vessel shear stress. Thus, twenty-four women were randomly assigned to either RMT or SHAM group. Maximal inspiratory mouth pressure and maximum voluntary ventilation were utilized to assess the effectiveness of the RMT program, which consisted of three sessions of isocapnic hyperventilation/ week for eight weeks, (twenty-four training sessions). Heart rate variability assessed autonomic balance, a global factor regulating the vasomotor response. Endothelial function was determined by measuring brachial artery vasodilation normalized by shear rate (%FMD/SR). After RMT, but not SHAM, maximal inspiratory mouth pressure and maximum voluntary ventilation increased significantly (+31% and +16%, respectively). Changes in heart rate variability were negligible in both groups. Only RMT exhibited a significant increase in %FMD/SR (+45%; p<0.05). These data suggest a positive effect of RMT on vasomotor response that may be due to a reduction in arterial shear stress, and not through modulation of sympatho-vagal balance

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-week 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 (sPLM) 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 &lt; 0.001) and + 20(2)%, (effect size: 2.43, P &lt; 0.001), respectively, albeit with a greater extent in SLKE [post-SLKE vs. post-PST: +56(8)%, (effect size: 2.92, P &lt; 0.001)]. Interestingly, the %FMD (standing for the systemic effect) increased after SLKE and PST by +12(2)% (effect size: 0.68, P &lt; 0.001) and + 11(1)% (effect size: 0.83, P &lt; 0.001), respectively, without any between-groups difference (P &gt; 0.05). No changes occurred in control. Conclusion: The present findings revealed that both active and passive training modalities induced similar improvements in the brachial artery dilatation capacity, while 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

Fall-risk factors in hospitalized elderly: the role of adapted physical activity

Purpose: Falls are common events in institutionalized elderly. Recent evidence suggests that several risk factors (FRFs) may be related to these falls. The aim of this study was to elucidate if some demographic and clinical factors are associated with the risk of falls in institutionalized elderly. The role of adapted physical activity (APA) in the risk of falls was also assessed. Methods: With a Kaplan\u2013Meier statistical model, the mean survivor time (MST) to a fall event was recorded for 6 months in 128 new-admitted patients to nursing home. Demographic factors such as sex, age, stature, body mass or other FRFs such as fall recidivism, gait and balance performance, cognitive impairment, activity of daily living (ADL) levels, Parkinson\u2019s disease, utilization of gait assistant devices, and the employment of a program of APA were considered potential co-variants. Results: Thirty patients experienced a fall during the observation period (6 months) with an overall MST of 154.8 \ub1 4.6 (range 2\u2013167) days. Moreover, history of previous fallen, reduced gait capacity, poor cognitive function, limited performance in the ADL, and Parkinson\u2019s disease were associated with a reduced MST to a fall event. While at contrary, the employment of the APA significantly reduced the fall-risk. Conclusions: Our results suggest the effectiveness of an APA program for the prevention of falling in institutionalized elderly. Moreover, new-admitted patients to nursing homes with a history of previous fallen, reduced gait capacity, poor cognitive function, limited performance in the ADL, and Parkinson\u2019s disease are associated with an increased risk of fallen. \ua9 2016, Springer-Verlag Italia

Neuromuscular versus mechanical stretch-induced changes in contra- versus ipsilateral muscle

PURPOSE: Whether or not the homologous contralateral muscle (CM) undergoes stretch-induced force reduction as the stretched muscle (SM) is still unclear. The neuromuscular and mechanical factors underlying the force reduction in CM and SM were investigated. METHODS: Twenty-one participants underwent unilateral knee-extensors passive stretching. In both CM and SM, before, immediately after (POST), 5 (POST5) and 10 min (POST10) after passive stretching, maximum voluntary contraction (MVC), peak force (pF) and voluntary activation (VA) were measured. During MVC, the electromyographic and mechanomyographic root mean square (EMG RMS and MMG RMS, respectively) was calculated in rectus femoris, vastus lateralis and vastus medialis, together with M-wave. The total electromechanical delay (EMD), divided in Δt EMG-MMG and Δt MMG-F was calculated. RESULTS: In CM at POST, the decrease in MVC [-11%, CI95% -13 to -9, effect size(ES): -2.27] was accompanied by a fall in VA (-7%, -9 to -4, ES: -2.29), EMG RMS (range -22 to -11%, ES: -3.92 to -2.25), MMG RMS (range -10 to -8%, ES: -0.52 to -0.39) and an increase in Δt EMG-MMG (≈+10%, ES: 0.73 to 0.93). All changes returned to baseline at POST5. In SM, decrease in MVC (-19%, -24 to -18, ES: -3.08), pF (-25%, -28 to -22, ES: -4.90), VA (-10%, -11 to -9, ES: -5.71), EMG RMS (≈-33%, ES: -5.23 to -3.22) and rise in MMG RMS (range +25 to +32%, ES: 4.21 to 4.98) and EMD (≈+28%, ES: 1.59 to 1.77) were observed at POST and persisted at POST10. No change in M-wave occurred. CONCLUSIONS: The contralateral central motor drive stretch-induced inhibition seems to account for the force reduction in CM. In SM, both central inhibition and mechanical factors concurred

Acute effects of static stretching on skeletal muscle relaxation at different ankle joint angles

Purpose: By combining electromyographic (EMG), mechanomyographic (MMG) and force analysis, the electromechanical delay during muscle relaxation (R-DelayTOT) was partitioned into electrochemical and mechanical components. The study aimed to evaluate the effects of changes in joint angle on R-DelayTOT components during relaxation after electrically evoked contractions before and after static stretching (SS) administration. Methods: Nineteen male participants (age 24 \ub1 3 years; body mass 76.4 \ub1 8.9 kg; stature 1.78 \ub1 0.09 m; mean \ub1 SD) were evaluated. Passive torque (Tpass) of the plantarflexor muscles was measured at 0\ub0, 10\ub0, and 20\ub0 of dorsiflexion to determine joint stiffness. The maximum electrically evoked torque (pT) was also recorded at each angle. During pT, force, EMG and MMG signals were detected for offline calculations of R-DelayTOT and its electrochemical and mechanical components. The same procedures were repeated after SS. Results: With increase in dorsiflexion angle, joint stiffness increased while R-DelayTOT and its mainly mechanical components decreased (from 128 to 20 %, P &lt; 0.05). After SS, joint stiffness decreased (from 16 to 20 %, P &lt; 0.05), while R-DelayTOT and its mainly mechanical components lengthened (from 8 to 28.5 %, P &lt; 0.05). Moreover, post-SS R-DelayTOT and its components decreased with the increase in joint angle (from 1213 to 31 %, P &lt; 0.05). Conclusion: The reduction in R-DelayTOT with increase in joint angle could be ascribed to the increase in joint stiffness, and not to alterations of the electrochemical processes during relaxation. SS lengthened R-DelayTOT and its components with a concomitant decrease in joint stiffness. Nevertheless, the reduction of the R-DelayTOT mainly mechanical components seen with dorsiflexion was similar to that before SS. \ua9 2016, Springer-Verlag Italia