Cardiovascular Responses to Skeletal Muscle Stretching: “Stretching” the Truth or a New Exercise Paradigm for Cardiovascular Medicine?

Muscular Performance and Blood Pressure After Different Pre-Strength Training Strategies in Recreationally Strength-Trained Women: Cross-Over Trial

BACKGROUND

This study aimed to investigate the acute effects of different pre-ST strategies on muscular performance and blood pressure (BP) responses in recreationally strength-trained women.

METHODS

Twelve overweight women with normal BP were recruited and performed six experimental protocols in a randomized order: (1) control protocol (CC), where BP was assessed without exercises performed; (2) ST; (3) foam rolling warm-up followed by ST (FR + ST); (4) specific warm-up followed by ST (SW + ST); (5) aerobic exercise followed by ST (AE + ST); and (6) stretching exercises followed by ST (SE + ST). ST consisted of three sets at 80% of 10 repetition maximum with a self-suggested rest interval between sets for bench press, back squat, bench press 45°, front squat, lat pull-down, leg press, shoulder press, and leg extension.

RESULTS

All experimental protocol had a lower total training volume, fatigue index, and repetitions performance in relation to ST (p < 0.05). No significant reduction was observed in systolic and diastolic BP for any protocol or exercise, although the effect size magnitudes ranged from trivial to large. Decreases in maximum repetitions, resistance to fatigue, and total training volume were performed before ST as warm-up strategies. However, these strategies indicated a clinical reduction in BP with a large and meaningful magnitude (effect size) in recreationally strength-trained women with normal to elevated BP.

CONCLUSIONS

The results of this investigation may help to influence decision-making by practitioners who desire to elicit a post-exercise hypotension response in both subjects with normal BP and hypertension.

Acute self-myofascial release modulates cardiac autonomic function and hemodynamic parameters at rest and reduces cardiovascular stress reaction

PURPOSE

Self-myofascial release (SMR) is a form of self-massage aiming to release tension, improve blood flow, and alleviate muscle soreness. This study aimed to determine whether a single session of SMR could impact cardiovascular parameters at rest and during a cold pressor test (CPT).

METHODS

Twenty male participants (aged 26 ± 2 years) underwent a 20-min SMR and a 20-min seated control condition (CON) on two separate test days in a randomized order. Peripheral and central blood pressure (BP), total peripheral resistance (TPR), pulse wave velocity (PWV), heart rate (HR), root mean square of successive RR interval differences (RMSSD), and the quotient of low-frequency power and high-frequency power (LF/HF) were measured both at rest and during a CPT before (t0), 2 min (t1), and 20 min (t2) after the SMR and CON.

RESULTS

Time × condition interactions could be detected for peripheral and central diastolic BP, TPR, HR, and RMSSD. Following the SMR, peripheral diastolic BP, central diastolic BP, TPR, and RMSSD were reduced, while HR was increased compared to the CON. Regarding the CPT time × condition interactions could be detected for peripheral, and central diastolic BP, with lower values after SMR.

CONCLUSION

The results of the present study suggest that a single bout of SMR confers favorable cardiovascular benefits in healthy normotensive individuals. Furthermore, SMR can attenuate the hemodynamic reactivity to a stress test. Future research should address whether regular SMR leads to chronic adaptations similar to regular, moderate aerobic exercise, massage therapy, and static stretching.

The Effects of Stretching Exercise on Levels of Blood Glucose: A Systematic Review with Meta-Analysis

BACKGROUND

Physical activity plays an important role in the management of blood glucose levels. However, compelling evidence exists only for aerobic and resistance training. In this review, we aimed to identify the potential effects of stretching exercises on blood glucose levels.

METHODS

A systematic literature search was performed using the following databases: Scopus, NLM PubMed, and Web of Science. Studies regarding the effects of stretching exercise in humans on blood glucose or any related variable were included. Further inclusion criteria were: (1) original articles (published from database inception to October 2022), (2) applying stretching as a unique exercise modality, (3) having either longitudinal or acute interventions, (4) including healthy and pathological populations, and (5) having within each study a pre- and post-intervention measure. Quality assessment of the studies was conducted using the Downs and Black checklist.

RESULTS

A total of 13 articles were included. The quality assessment revealed an overall moderate quality of the included records. Ten articles included patients with type 2 diabetes (T2D), whereas the remaining three included at-risk populations. A total of 731 people with a mean age of 56.7 ± 6.1 years old were analysed. Fasting blood glucose, 2 h post-oral glucose uptake, post-stretching intervention blood glucose levels, and HbA1c were identified as variables related to blood glucose within the studies. After the stretching interventions, a significant reduction was observed in either blood glucose (ES = - 0.79; p = 0.0174) or HbA1c (ES = - 1.11; p =  < 0.0001). Meta-analytic results highlighted greater effects in T2D patients (ES = - 1.15; p = 0.02) and for studies applying stretching as an exercise intervention (ES = - 1.27; p = 0.006) rather than considering stretching as a control exercise modality.

CONCLUSION

The results of this systematic review highlight the potential of stretching exercises to reduce blood glucose levels. In particular, if stretching is applied as a specific form of exercise intervention in patients with T2D greater effects are observed. However, further studies with more solid research designs are required, therefore, caution is needed before prescribing stretching as an exercise intervention for glycaemic management.

Enhance range-of-motion and hypotensive effect in elderly submitted to three manual therapy techniques: Cross-over study

The present study has two objectives: 1) to verify the effect of Maitland mobilization, manual massage (MM), and static stretching (SS) on the acute range-of-motion (ROM) responses, over 30 min, in the elderly; 2) to verify the effect of Maitland's mobilization, MM, and SS on blood pressure (BP) responses, over 60 min, in the elderly. Sixteen inactive elderly men were recruited. After familiarization, all subjects performed the experimental conditions throughout four remaining sessions. Each session included two baselines ROM measures in randomized order. After baseline, participants completed the control group, Maitland, MM, and SS conditions and retesting immediately (Post-0) e again throughout 30-min following intervention. All conditions increased ankle, hip, and shoulder ROM for at least 10-min post-intervention. Systolic BP hypotensive effects were found for all experimental protocols when compared to baseline values. In conclusion, it was observed that Maitland, MM, and SS conditions enhance ROM and promote hypotensive effect post-intervention. These results have a practical prescription and rehabilitation implications and may be used in the elderly population, since a movement limitation can be treated by global interventions in a non-limited, as well as promoting cardiovascular protection through the hypotensive effects in the same experimental session.

Fourteen weeks of multicomponent training associated with flexibility training modifies postural alignment, joint range of motion and modulates blood pressure in physically inactive older women: a randomized clinical trial

Background: Body relaxation and pain reduction are some of the reported benefits of flexibility training (through active stretching exercises), however their effects on posture and blood circulation are uncertain. We aimed to investigate the effects of flexibility training (through active stretching exercises) in combination with multicomponent training (MT) on blood pressure (BP), and the correlation with changes in body alignment and flexibility in physically inactive women. Methods: Women aged 60-70 years were into three groups: multicomponent training group (MT), multicomponent training plus flexibility training group (FT), and control group (CG). After randomization, the resting blood pressure was measured and the participants were reallocated into subgroups according to pressure values >130/80 mmHg (This classification is according to the American Heart Association (AHA), resulting in the subgroups: flexibility training (FT); flexibility training for hypertensive patients (FTSAH); multicomponent training (MT); multicomponent training for hypertensive patients (MTSAH); control group (CG); control group of hypertensive patients (CGSAH). The interventions lasted 14 weeks. Systolic (sBP) and diastolic (dBP) BP, range of motion (flexion and extension), and postural analysis by asymmetry in the frontal plane and asymmetry in the sagittal plane, displacement and the flexibility test were collected before (Pre) and after training (Post). In total, 141 women participated in the study (without SAH: FT = 23, MT = 20, and CG = 21; with SAH: FTSAH = 28, MTSAH = 23, and CGSAH = 26). Results: Systolic blood pressure, in the pre and post moments were: FT (116 ± 6.7 vs. 114 ± 4.7); FTSAH (144 ± 16.5 vs. 121 ± 10.1); MT: (120 ± 6.8 vs. 121 ± 7.3); MTSAH: (137 ± 10.6 vs. 126 ± 13.0); CG: (122 ± 5.3 vs. 133 ± 19.2); and CGSAH: (140 ± 9.7 vs. 143 ± 26.2), presenting an F value (p-value - group x time) of 12.00 (<0.001), with improvement in the groups who trained. The diastolic blood pressure in the pre and post moments were: FT (71 ± 4.7 vs. 74 ± 6.8); FTSAH (88 ± 9.6 vs. 70 ± 12.0); MT: (74 ± 4.5 vs. 77 ± 11.7); MTSAH: (76 ± 10.4 vs. 76 ± 10.2); CG: (69 ± 7.11 vs. 82 ± 11.4); and CGSAH: (76 ± 13.4 vs. 86.6 ± 7.7), presenting an F value (p-value - group x time) of 8.00 (p < 0.001), with improvement in the groups who trained. In the Elastic Net Regression, sBP was influenced by height (β: -0.044); hip flexion (β: 0.071); Shoulder extension (β: 0.104); low back flexion (β: 0.119) and dBP (β: 0.115). In the Elastic Net Regression, dBP was influenced by asymmetry in the sagittal plane variables (0.040); asymmetry in the frontal plane (β: 0.007); knee flexion (β: -0.398); BM (β: 0.007); Shoulder flexion (β: -0.142); Hip flexion (β: -0.004); sBP (β: 0.155) and Ankle Flexion (β: -0.001). Conclusion: The displacement of the asymmetry in the frontal plane and asymmetry in the sagittal plane, and the increase in the flexion position in the hip, lumbar, head, and knee regions, influenced the highest-pressure levels. Multicomponent training associated with flexibility training promoted improvement in body alignment, COM, and joint angles, and decreased blood pressure.

Health policy considerations for combining exercise prescription into noncommunicable diseases treatment: a narrative literature review

Objectives

In this review, we aim to highlight the evidence base for the benefits of exercise in relation to the treatment of noncommunicable diseases (NCDs), draw on the Health Triangular Policy Framework to outline the principal facilitators and barriers for implementing exercise in health policy, and make concrete suggestions for action.

Methods

Literature review and framework analysis were conducted to deal with the research questions.

Results

Exercise prescription is a safe solution for noncommunicable diseases prevention and treatment that enables physicians to provide and instruct patients how to apply exercise as an important aspect of disease treatment and management. Combining exercise prescription within routine care, in inpatient and outpatient settings, will improve patients' life quality and fitness levels.

Conclusion

Inserting exercise prescription into the healthcare system would improve population health status and healthy lifestyles. The suggestions outlined in this study need combined efforts from the medical profession, governments, and policymakers to facilitate practice into reality in the healthcare arena.

Preexercise intermittent passive stretching and vascular function after treadmill exercise

Acute aerobic exercise stress is associated with decreased endothelial function that may increase the likelihood of an acute cardiovascular event. Passive stretch (PS) elicits improvements in vascular function, but whether PS can be performed before exercise to prevent declines in vascular function remains unknown. This strategy could be directly applicable in populations that may not be able to perform dynamic exercise. We hypothesized that preexercise PS would provide better vascular resilience after treadmill exercise. Sixteen healthy college-aged males and females participated in a single laboratory visit and underwent testing to assess micro- and macrovascular function. Participants were randomized into either PS group or sham control group. Intermittent calf PS was performed by having the foot in a splinting device for a 5-min stretch and 5-min relaxation, repeated four times. Then, a staged V̇o2 peak test was performed and 65% V̇o2 peak calculated for subjects to run at for 30 min. Near-infrared spectroscopy-derived microvascular responsiveness was preserved with the PS group [(pre: 0.53 ± 0.009%/s) (post: 0.56 ± 0.012%/s; P = 0.55)]. However, there was a significant reduction in the sham control group [(pre: 0.67 ± 0.010%/s) (post: 0.51 ± 0.007%/s; P = 0.05)] after treadmill exercise. Flow-mediated vasodilation (FMD) of the popliteal artery showed similar responses. In the PS group, FMD [(pre: 7.23 ± 0.74%) (post: 5.86 ± 1.01%; P = 0.27)] did not significantly decline after exercise. In the sham control group, FMD [(pre: 8.69 ± 0.72%) (post: 5.24 ± 1.24%; P < 0.001)] was significantly reduced after treadmill exercise. Vascular function may be more resilient if intermittent PS is performed before moderate-intensity exercise and, importantly, can be performed by most individuals.NEW & NOTEWORTHY We demonstrate for the first time that popliteal artery and gastrocnemius microvascular responsiveness after acute aerobic exercise are reduced. The decline in vascular function was mitigated in those who performed intermittent passive stretching before the exercise bouts. Collectively, these findings suggest that intermittent passive stretching is a novel method to increase vascular resiliency before aerobic activity.

Cross-sectional and longitudinal associations between body flexibility and sarcopenia

BACKGROUND

The associations between body flexibility and sarcopenia were not well understood. This study aimed to explore the cross-sectional and longitudinal associations of flexibility with sarcopenia.

METHODS

Our study selected participants aged 50-80 from the WELL-China cohort and the Lanxi cohort. Participants from the urban area of the Lanxi cohort were followed up 4 years later. Body flexibility was measured by the sit-and-reach test. Muscle mass was evaluated by dual-energy X-ray absorptiometry. Muscle strength was evaluated using handgrip strength. Sarcopenia was defined as having both low muscle mass and low muscle strength. We used multivariable logistic regressions to assess the cross-sectional associations of body flexibility with low muscle mass, low muscle strength and sarcopenia. We also used multivariable logistic regressions to explore the associations of baseline flexibility and 4-year changes in flexibility with incident low muscle mass, low muscle strength and sarcopenia.

RESULTS

A total of 9453 participants were enrolled in the cross-sectional study, and 1233 participants were included in the longitudinal analyses. In the cross-sectional analyses, compared with low body flexibility, high body flexibility was inversely associated with low muscle mass (odds ratio [OR], 0.58; 95% confidence interval [CI], 0.50-0.68; P < 0.001), low muscle strength (OR, 0.62; 95% CI, 0.55-0.69; P < 0.001) and sarcopenia (OR, 0.52; 95% CI, 0.41-0.65; P < 0.001), and these associations did not differ in different age groups, sex or physical activity levels. In the longitudinal analyses, compared with participants with low body flexibility, participants with high body flexibility had lower risk of the incident low muscle strength (OR, 0.53; 95% CI, 0.38-0.74; P < 0.001) and sarcopenia (OR, 0.36; 95% CI, 0.21-0.61; P < 0.001), but not incident low muscle mass (OR, 0.59; 95% CI, 0.33-1.06; P = 0.076). Every 1-cm increase in flexibility during 4 years was associated with reduced risk of incident low muscle mass (OR, 0.96; 95% CI, 0.93-1.00; P = 0.025), low muscle strength (OR, 0.96; 95% CI, 0.94-0.98; P = 0.002) and sarcopenia (OR, 0.96; 95% CI, 0.93-0.99; P = 0.007).

CONCLUSIONS

High flexibility was associated with reduced risk of incident low muscle strength and sarcopenia. Increases in flexibility were associated with reduced risk of incident low muscle mass, low muscle strength and sarcopenia. Flexibility exercises and monitoring the dynamic change of flexibility might be helpful in preventing sarcopenia among adults aged 50 years or over.

Physical Exercise Effects on Cardiovascular Autonomic Modulation in Postmenopausal Women-A Systematic Review and Meta-Analysis

BACKGROUND

The cardioprotective effect of physical exercise has been demonstrated in several studies. However, no systematic or updated analysis has described the effects of physical exercise on cardiovascular autonomic modulation in postmenopausal women.

AIM

to describe the effects of physical exercise on cardiovascular autonomic modulation in postmenopausal women.

METHODS

The Scopus, PubMed, and Embase databases were searched for randomized clinical trials published between January 2011 and December 2021, and regarding the effects of physical exercise on cardiovascular autonomic modulation in postmenopausal women. Two independent authors processed the citations. The methodological quality was evaluated using the PEDRo scale.

RESULTS

Of the 91 studies identified, only 8 met the inclusion criteria, of which 7 had fair or poor methodological quality. The analyzed studies investigated the effects of functional training, whole-body vibration, muscular resistance, stretching, and aerobic exercises performed at home or at the gym. The majority of these exercise modalities showed improvements in heart-rate variability (HRV) indices and in the low-frequency band of blood pressure variability. The meta-analysis shows that exercise increased the standard deviation of instantaneous beat-to-beat variability (SD1) (mean difference (MD) = 3.99; 95% confidence interval (CI) = 1.22 to 6.77, n = 46; I²: 0%) and the standard deviation of long-term variability (SD2) (MD = 11.37; 95% CI = 2.99 to 19.75; n = 46; I²: 0%).

CONCLUSIONS

Aerobic exercise and some nonconventional training modalities may have beneficial effects on cardiovascular autonomic modulation in postmenopausal women. More high-quality studies are still needed to further confirm their efficacy and safety.

Effects of nociceptive and mechanosensitive afferents sensitization on central and peripheral hemodynamics following exercise-induced muscle damage

This study aims to test the separated and combined effects of mechanoreflex activation and nociception through exercise-induced muscle damage (EIMD) on central and peripheral hemodynamics before and during single passive leg movement (sPLM). Eight healthy young males undertook four experimental sessions, in which a sPLM was performed on the dominant limb while in each specific session the contralateral was: 1) in a resting condition (CTRL), 2) stretched (ST), 3) resting after EIMD called delayed onset muscle soreness (DOMS) condition, or 4) stretched after EIMD (DOMS + ST). EIMD was used to induce DOMS in the following 24-48 h. Femoral blood flow (FBF) was assessed using Doppler ultrasound whereas central hemodynamics were assessed via finger photoplethysmography. Leg vascular conductance (LVC) was calculated as FBF/mean arterial pressure (MAP). RR-intervals were analyzed in the time (root mean squared of successive intervals; RMSSD) and frequency domain [low frequency (LF)/high frequency (HF)]. Blood samples were collected before each condition and gene expression analysis showed increased fold changes for P2X4 and IL1β in DOMS and DOMS + ST compared with baseline. Resting FBF and LVC were decreased only in the DOMS + ST condition (-26 mL/min and -50 mL/mmHg/min respectively) with decreased RMSSD and increased LF/HF ratio. MAP, HR, CO, and SV were increased in ST and DOMS + ST compared with CTRL. Marked decreases of Δpeaks and AUC were observed for FBF (Δ: -146 mL/min and -265 mL respectively) and LVC (Δ: -8.66 mL/mmHg/min and ±1.7 mL/mmHg/min respectively) all P < 0.05. These results suggest that the combination of mechanoreflex and nociception resulted in decreased vagal tone and concomitant rise in sympathetic drive that led to increases in resting central hemodynamics with reduced limb blood flow before and during sPLM.NEW & NOTEWORTHY Exercise-induced muscle damage (EIMD) is a well-known model to study mechanical hyperalgesia and muscle peripheral nerve sensitizations. The combination of static stretching protocol on the damaged limb extensively increases resting central hemodynamics with reduction in resting limb blood flow and passive leg movement-induced hyperemia. The mechanism underlining these results may be linked to reduction of vagal tone with concomitant increase in sympathetic activity following mechano- and nociceptive activation.

Effects of Manual Therapies and Resistance Exercise on Postexercise Hypotension in Women With Normal Blood Pressure

ABSTRACT

Monteiro, ER, Pescatello, LS, Winchester, JB, Corrêa Neto, VG, Brown, AF, Budde, H, Marchetti, PH, Silva, JG, Vianna, JM, and Novaes, JdS. Effects of manual therapies and resistance exercise on postexercise hypotension in women with normal blood pressure. J Strength Cond Res 36(4): 948-954, 2022-The purpose of this investigation was to examine the acute effects of resistance exercise (RE) and different manual therapies (static stretching and manual massage [MM]) performed separately or combined on blood pressure (BP) responses during recovery in women with normal BP. Sixteen recreationally strength-trained women (age: 25.1 ± 2.9 years; height: 158.9 ± 4.1 cm; body mass: 59.5 ± 4.9 kg; body mass index: 23.5 ± 1.9 kg·m-2; baseline systolic BP median: 128 mm Hg; and baseline diastolic BP median: 78 mm Hg) were recruited. All subjects performed 6 experiments in a randomized order: (a) rest control (CON), (b) RE only (RE), (c) static-stretching exercise only (SS), (d) MM only, (e) RE immediately followed by SS (RE + SS), and (f) RE immediately followed by MM (RE + MM). RE consisted of 3 sets of bilateral bench press, back squat, front pull-down, and leg press exercises at 80% of 10RM. Static stretching and MM were applied unilaterally in 2 sets of 120 seconds to each of the quadriceps, hamstring, and calf regions. Systolic (SBP) and diastolic BP were measured before (rest) and every 10 minutes for 60 minutes following (Post 10-60) each intervention. There were significant intragroup differences for RE in Post-50 (p = 0.038; d = -2.24; ∆ = -4.0 mm Hg). Similarly, SBP intragroup differences were found for the SS protocol in Post-50 (p = 0.021; d = -2.67; ∆ = -5.0 mm Hg) and Post-60 (p = 0.008; d = -2.88; ∆ = -5.0 mm Hg). Still, SBP intragroup differences were found for the MM protocol in Post-50 (p = 0.011; d = -2.61; ∆ = -4.0 mm Hg) and Post-60 (p = 0.011; d = -2.74; ∆ = -4.0 mm Hg). Finally, a single SBP intragroup difference was found for the RE + SS protocol in Post-60 (p = 0.024; d = -3.12; ∆ = -5.0 mm Hg). Practitioners should be aware that SS and MM have the potential to influence BP responses in addition to RE or by themselves and therefore should be taken into consideration for persons who are hypertensive or hypotensive.

The Protective Role of Physical Fitness on Cardiometabolic Risk During Pregnancy: The GESTAtion and FITness Project

Physical fitness (PF) is a cornerstone of metabolic health. However, its role in maternal-fetal metabolism during pregnancy is poorly understood. The present work investigates: (i) the association of PF with maternal and fetal cardiometabolic markers, and with clustered cardiometabolic risk during pregnancy, and (ii) whether being fit counteracts cardiometabolic abnormalities associated with overweight/obesity. Several PF components (flexibility, lower and upper body strength, and cardiorespiratory fitness [CRF]) were objectively assessed in 151 pregnant women at gestational weeks 16 and 33, and an overall PF cluster score calculated. At the same times, maternal glycemic and lipid markers, cortisol, and C-reactive protein were assessed with standard biochemical methods, along with blood pressure and a proxy for insulin resistance, and a cardiometabolic risk cluster score determined. These analytes were also measured in maternal and umbilical cord arterial and venous blood collected at delivery. PF was found to be associated with several maternal and a small number of fetal cardiometabolic markers (p < .05). Lower and upper body muscle strength, CRF, overall PF (week 16), and CRF changes (weeks 16-33) were inversely associated with clustered cardiometabolic risk (p < .05). Normal weight fit women had lower values for insulin level, insulin resistance, triglycerides, low-density lipoprotein cholesterol, C-reactive protein, and diastolic blood pressure than did overweight/obese unfit women at week 16 (p < .05). In conclusion, greater PF, especially muscle strength and CRF in early-middle pregnancy, appears to be associated with a better metabolic phenotype, and may protect against maternal cardiometabolic risk. "Keep yourself fit and normal weight before and during early pregnancy" should be a key public health message.

Gym and home-based combined training in men with primary hypertension: are they equally effective on functional fitness profile, body composition components, and biochemical parameters of hypertension?

OBJECTIVE

This study aimed to compare the effects of 10 weeks of gym versus home-based combined training on the functional fitness, body composition, and biochemical parameters of hypertension in primary hypertensive men.

METHODS

Forty-six patients (age 48 ± 9 years, BMI 30 ± 4 kg/m²) assigned into three groups: a gym-based combined training (GBCTr: n = 16; resistance at 60-80% of 1RM, using pin-loaded resistance equipment, aerobic at 40-60% HRR, and stretching), home-based combined training (HBCTr: n = 15; resistance at 12-15 RPE, using an elastic exercise band, aerobic at 40-60% HRR, and stretching), and control (CTR, n = 15).

RESULTS

Following GBCTr and HBCTr, the functional aerobic capacity (P = .005 and P = .004, respectively), flexibility (P = .01 and P = .004, respectively), and lower limb muscle strength (P = .01 and P = .02, respectively) was increased significantly compared with the CTR group. The body weight (P = .02), body mass index (P = .008), hip circumference (P = .02), and nitric oxide level in GBCTr and HBCTr group (P = .002 and P = .02, respectively) was decreased significantly compared with the CTR group. No significant changes found in the plasma levels of NADPH oxidase 5, thioredoxin-2, thioredoxin reductase-2, and resting blood pressure after GBCTr and HBCTr compared with the CTR group.

CONCLUSION

These results suggest that in hypertensive men, HBCTr equally to GBCTr improved functional fitness and body composition remarkably without necessarily reducing resting blood pressure. Therefore, they can be advisable substitutes for gaining health benefits.

Neuromuscular Correlates of the Contralateral Stretch-induced Strength Loss

PURPOSE

The current study investigated the effects of unilateral passive stretching on the neuromuscular mechanisms involved in the force-generating capacity of the contralateral muscle.

METHODS

Twenty-six healthy men underwent unilateral passive stretching of the plantarflexors (5 × 45 s on + 15 s off; total stretching time, 225 s). Before and after the stretching protocol, contralateral ankle range of motion, maximum voluntary contraction (MVC) of the plantarflexors, and surface electromyographic root-mean-square (sEMG RMS) of the soleus and the gastrocnemii muscles were determined. Concurrently, V-wave, maximum and superimposed H-reflex, and M-wave were elicited via nerve stimulation to estimate the supraspinal, spinal, and peripheral mechanisms, respectively. sEMG RMS, V-wave, and H-reflex were normalized to the M-wave.

RESULTS

After passive stretching, contralateral ankle range of motion was increased (+8% [1%/15%], effect size [ES] = 0.43 [0.02/0.84], P < 0.001), MVC of the plantarflexors was decreased (-9% [-21%/-2%], ES = -0.96 [-1.53/-0.38], P < 0.001), and the sEMG RMS/M-wave of the soleus and the gastrocnemii muscles was decreased (≈-9%, ES ≈ -0.33, P < 0.05). Concurrently, the V-wave/M-wave superimposed was decreased in all muscles (≈-13%, ES = -0.81 to -0.52, P < 0.05). No change in H-reflex/M-wave and M-wave was observed under both maximum and superimposed condition. The decrease in the MVC and the sEMG RMS of the contralateral muscle was accompanied by a decrease in the V-wave/M-wave but not the H-reflex/M-wave ratios and the M-wave.

CONCLUSIONS

The present outcomes suggest that only supraspinal mechanisms might be involved in the contralateral decrease in the maximum force-generating capacity.

Changes in the Allostatic Response to Whole-Body Cryotherapy and Static-Stretching Exercises in Chronic Fatigue Syndrome Patients vs. Healthy Individuals

This study represents a comparison of the functional interrelation of fatigue and cognitive, cardiovascular and autonomic nervous systems in a group of Chronic Fatigue Syndrome (CFS) patients compared with those in healthy individuals at different stages of analysis: at baseline and after changes induced by whole-body cryotherapy (WBC) combined with a static-stretching (SS) program. The study included 32 patients (Fukuda criteria) and 18 healthy controls. Fatigue, cognitive, cardiovascular and autonomic function and arterial stiffness were measured before and after 10 sessions of WBC with SS. In the patients, a disturbance in homeostasis was observed. The network relationship based on differences before and after intervention showed comparatively higher stress and eccentricity in the CFS group: 50.9 ± 56.1 vs. 6.35 ± 8.72, p = 0.002, r = 0.28; and 4.8 ± 0.7 vs. 2.4 ± 1, p < 0.001, r = 0.46, respectively. Before and after intervention, in the CFS group increased fatigue was related to baroreceptor function, and baroreceptor function was in turn related to aortic stiffness, but no such relationships were observed in the control group. Differences in the network structure underlying the interrelation among the four measured criteria were observed in both groups, before the intervention and after ten sessions of whole cryotherapy with a static stretching exercise.

Peripheral Nerve Responses to Muscle Stretching: A Systematic Review

Stretching is commonly used to increase range of motion and flexibility. Therefore, investigations are usually oriented towards the muscle-tendon unit. Limited evidence exists regarding potential effects of stretching on peripheral nerves which lie within muscles. The objective of this investigation will be to elucidate the responses of peripheral nerves to stretching. A literature search was performed using the following databases: Scopus, NLM Pubmed and ScienceDirect. Studies regarding the effects of stretching protocols on responses of peripheral nerves were retrieved for investigation. The NHLBI tool was used for quality assessment. Outcomes included nerve stiffness, nerve displacement, pain pressure thresholds and resistive torque. A total of 10 studies were considered eligible and were included in this investigation. The quality assessment of the studies revealed an overall "fair to good" methodological quality across the included studies. All studies except for one involved healthy participants. High heterogeneity of stretching protocols was retrieved. As a consequence of stretching, nerve stiffness (-15.6%) and pain pressure thresholds (-1.9kg) increased. Nerve displacements on each movement plane for all the considered nerves and nerve deformation were also frequently observed. Peripheral nerve responses to muscle stretching include decreased nerve stiffness and increased pain pressure thresholds. Nerve displacement also frequently occurs. It is still unclear if reduced nerve displacement may lead to clinical outcomes. There is a lack of longitudinal studies regarding peripheral nerve adaptations to stretching.

Effects of Acute Stretching Exercise and Training on Heart Rate Variability: A Review

ABSTRACT

Wong, A and Figueroa, A. Effects of acute stretching exercise and training on heart rate variability: A review. J Strength Cond Res 35(5): 1459-1466, 2021-Stretching (ST), an exercise modality widely used for flexibility improvement, has been recently proposed as an effective adjunct therapy for declines in cardiovascular health, warranting research into the effects of ST exercise on cardiac autonomic function (CAF). Heart rate (HR) variability (HRV) is a reliable measure of CAF, mainly the sympathetic and parasympathetic modulations of HR. A low HRV has been associated to increased risk of cardiovascular events and mortality. Exercise interventions that enhance HRV are therefore seen as beneficial to cardiovascular health and are sought after. In this review, we discuss the effect of ST both acute and training on HRV. Stretching training seems to be a useful therapeutic intervention to improve CAF in different populations. Although the mechanisms by which ST training improves CAF are not yet well understood; increases in baroreflex sensitivity, relaxation, and nitric oxide bioavailability seem to play an important role.

The Case for Retiring Flexibility as a Major Component of Physical Fitness

Flexibility refers to the intrinsic properties of body tissues that determine maximal joint range of motion without causing injury. For many years, flexibility has been classified by the American College of Sports Medicine as a major component of physical fitness. The notion flexibility is important for fitness has also led to the idea static stretching should be prescribed to improve flexibility. The current paper proposes flexibility be retired as a major component of physical fitness, and consequently, stretching be de-emphasized as a standard component of exercise prescriptions for most populations. First, I show flexibility has little predictive or concurrent validity with health and performance outcomes (e.g., mortality, falls, occupational performance) in apparently healthy individuals, particularly when viewed in light of the other major components of fitness (i.e., body composition, cardiovascular endurance, muscle endurance, muscle strength). Second, I explain that if flexibility requires improvement, this does not necessitate a prescription of stretching in most populations. Flexibility can be maintained or improved by exercise modalities that cause more robust health benefits than stretching (e.g., resistance training). Retirement of flexibility as a major component of physical fitness will simplify fitness batteries; save time and resources dedicated to flexibility instruction, measurement, and evaluation; and prevent erroneous conclusions about fitness status when interpreting flexibility scores. De-emphasis of stretching in exercise prescriptions will ensure stretching does not negatively impact other exercise and does not take away from time that could be allocated to training activities that have more robust health and performance benefits.

Ideal cardiovascular health in women with systemic lupus erythematosus: Association with arterial stiffness, inflammation, and fitness

BACKGROUND

Systemic Lupus Erythematosus (SLE) is closely related to cardiovascular morbidity and mortality. We aimed to examine the association of ideal cardiovascular health (ICH) with arterial stiffness, inflammation, and physical fitness in women with SLE.

METHODS

This cross-sectional study included 76 women with SLE (age 43.4±13.8 years old). Ideal levels of 7 health metrics (smoking, body mass index, physical activity, healthy diet, blood pressure, cholesterol, and glucose) were used to define the ICH score (ranging from 0 to 7 ideal metrics) and the ICH status ( defined as presenting ≥4 ideal metrics). Arterial stiffness was measured through pulse wave velocity (PWV) and inflammation through serum high sensitivity C-reactive protein (hs-CRP). Cardiorespiratory fitness (CRF) was measured by 6-min walk test (6MWT), and Siconolfi step test and muscular strength by handgrip strength and 30-s chair stand, and range of motion (ROM) by the back-scratch test.

RESULTS

Higher ICH score was associated with lower PWV (β = -0.122, p = 0.002), lower hs-CRP (β = -0.234, p = 0.056), higher CRF [6MWT (β = 0.263, p = 0.041); Siconolfi step test (β = 0.330, p < 0.001)], higher ROM (β = 0.278, p = 0.013) and higher relative handgrip strength (β = 0.248, p = 0.024). Women with ICH status presented lower PWV (mean difference 0.40 m/s, 95% CI 0.17 to 0.63, p = 0.001), and higher CRF [assessed by 6MWT (mean difference 43.9 m, 95% CI 5.0 to 82.7, p = 0.028)], than women with non-ICH status. Sensitivity analyses using ICH score ranging 0-14 and considering ICH status with ≥5 metrics revealed consistent results.

CONCLUSION

ICH is associated with lower arterial stiffness, lower inflammation, and higher fitness in women with SLE. Although these results extend current knowledge about the potential role of ICH for primordial prevention of CVD in SLE, they are yet to be confirmed in future prospective research .

Cardiovascular Responses to Muscle Stretching: A Systematic Review and Meta-analysis

The aim of this study will be to review the current body of literature to understand the effects of stretching on the responses of the cardiovascular system. A literature search was performed using the following databases: Scopus, NLM Pubmed and ScienceDirect. Studies regarding the effects of stretching on responses of the cardiovascular system were investigated. Outcomes regarded heart rate(HR), blood pressure, pulse wave velocity (PWV of which baPWV for brachial-ankle and cfPWV for carotid-femoral waveforms), heart rate variability and endothelial vascular function. Subsequently, the effects of each outcome were quantitatively synthetized using meta-analytic synthesis with random-effect models. A total of 16 studies were considered eligible and included in the quantitative synthesis. Groups were also stratified according to cross-sectional or longitudinal stretching interventions. Quality assessment through the NHLBI tools observed a "fair-to-good" quality of the studies. The meta-analytic synthesis showed a significant effect of d=0.38 concerning HR, d=2.04 regarding baPWV and d=0.46 for cfPWV. Stretching significantly reduces arterial stiffness and HR. The qualitative description of the studies was also supported by the meta-analytic synthesis. No adverse effects were reported, after stretching, in patients affected by cardiovascular disease on blood pressure. There is a lack of studies regarding vascular adaptations to stretching.

Neuromuscular versus Mechanical Stretch-induced Changes in Contralateral 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 time delay (Δt) EMG-MMG and Δt MMG-F was calculated.

RESULTS

In CM at POST, the decrease in MVC (-11%; 95% confidence interval [CI], -13 to -9; effect size [ES], -2.27) was accompanied by a fall in VA (-7%; 95% CI, -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%; 95% CI, -24 to -18; ES, -3.08), pF (-25%; 95% CI, -28 to -22; ES, -4.90), VA (-10%; 95% CI, -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.

Passive muscle stretching reduces estimates of persistent inward current strength in soleus motor units

Prolonged (≥60 s) passive muscle stretching acutely reduces maximal force production at least partly through a suppression of efferent neural drive. The origin of this neural suppression has not been determined; however, some evidence suggests that reductions in the amplitude of persistent inward currents (PICs) in the motoneurons may be important. The aim of the present study was to determine whether acute passive (static) muscle stretching affects PIC strength in gastrocnemius medialis (GM) and soleus (SOL) motor units. We calculated the difference in instantaneous discharge rates at recruitment and de-recruitment (ΔF) for pairs of motor units in GM and SOL during triangular isometric plantar flexor contractions (20% maximum) both before and immediately after a 5 min control period and immediately after five 1 min passive plantar flexor stretches. After stretching, there was a significant reduction in SOL ΔF (-25.6%; 95% confidence interval, CI=-45.1% to -9.1%, P=0.002) but not GM ΔF These data suggest passive muscle stretching can reduce the intrinsic excitability, via PICs, of SOL motor units. These findings (1) suggest that PIC strength might be reduced after passive stretching, (2) are consistent with previously established post-stretch decreases in SOL but not GM EMG amplitude during contraction, and (3) indicate that reductions in PIC strength could underpin the stretch-induced force loss.

Additional Improvement of Respiratory Technique on Vascular Function in Hypertensive Postmenopausal Women Following Yoga or Stretching Video Classes: The YOGINI Study

Background: Hypertension remains highly prevalent in postmenopausal women, along with vascular dysfunction and increased oxidative stress. In such context, regular exercises, yoga practice, and slow breathing have been recommended to treat hypertension. However, the effects of the multiple components of yoga, including the respiratory techniques involved in the practice, on hypertension and on vascular and endothelial function have never been evaluated.

Objective: This study aimed to investigate the additional effects of respiratory technique on vascular function and oxidative stress profile in hypertensive postmenopausal women (HPMWs) following yoga or stretching video classes.

Study Design: Hypertensive postmenopausal women were recruited and randomized for 12 weeks, twice a week, of supervised yoga or stretching video classes of 75 min for 12 weeks associated or not with respiratory technique. Baseline and post-intervention measurements included pulse wave velocity (PWV), flow-mediated dilation (FMD), and oxidative stress parameters. Hypertensive postmenopausal women (59 ± 0.7 years) who ended the protocol were distributed into three groups: (1) control group (yoga or stretching, C, n = 14); (2) yoga + respiratory technique (Y+, n = 10); (3) stretching + respiratory technique (S+, n = 9).

Results: Diastolic blood pressure and FMD [baseline: C: 6.94 ± 1.97%, Y+: 7.05 ± 1.65%, and S+: 3.54 ± 2.01% vs. post: C: 16.59 ± 3.46% (p = 0.006), Y+: 13.72 ± 2.81% (p = 0.005), and S+: 11.79 ± 0.99% (p = 0.0001)] have significantly increased in all groups when baseline and post-practice values were compared. However, resting heart rate and PWV [baseline: Y+: 10.44 ± 3.69 and S+: 9.50 ± 0.53 m/s vs. post: Y+: 9.45 ± 0.39 (p = 0.003) and S+: 8.02 ± 0.47 m/s (p = 0.003)] decreased significantly only in the Y+ and S+ groups (baseline vs. post). Systemic antioxidant enzyme activities (superoxide dismutase and catalase) increased in all groups, and hydrogen peroxide and lipoperoxidation reduced in Y+ and S+ (baseline vs. post).

Conclusions: Twelve weeks of yoga or stretching video classes promoted positive changes in several outcomes generally regarded as cardiovascular risk factors in HPMWs, and these changes were even more pronounced by the association with respiratory technique.

Doctor, ask your perimenopausal patient about her physical fitness; association of self-reported physical fitness with cardiometabolic and mental health in perimenopausal women: the FLAMENCO project

OBJECTIVE

The aim of this study was to explore the association of self-reported physical fitness (PF) and its components with cardiometabolic and mental health in perimenopausal women.

METHODS

These cross-sectional analyses included 191 participants (53 ± 4 y old) from the FLAMENCO project. Self-reported PF was assessed with the International Fitness Scale (IFIS). Body mass index (BMI), fat mass (FM), waist circumference (WC), systolic and diastolic blood pressure (DBP), high-density lipoprotein cholesterol (HDL-C), triglycerides, C-reactive protein (CRP), and glucose were measured. The Beck's Depression Inventory, State-Trait Anxiety Inventory, Pittsburgh Sleep Quality Index, Life Orientation Test Revised, and Positive and Negative Affect Schedule were used to assess mental health.

RESULTS

After adjusting for potential confounders, greater overall PF was associated with lower BMI, FM, WC (P < 0.001), DBP and CRP, and higher HDL-C (P < 0.05). Cardiorespiratory fitness (CRF), speed-agility, and flexibility were associated with lower BMI, WC, and FM (P < 0.001), and muscle strength (MS) with lower WC and FM (P < 0.05). In addition, CRF, MS, and speed-agility were associated with lower CRP (P < 0.01), and flexibility with enhanced triglycerides and HDL-C (P < 0.05). Overall PF and all its components were associated with lower depression, anxiety, and negative affect (P≤0.01), and greater positive affect (P≤0.05). Overall PF and MS were associated with better sleep quality (P < 0.05), and CRF, MS, and speed-agility with greater optimism (P≤0.05). Finally, overall PF showed evidence of significant association with less pharmaceutical expenditure (B = -7.2, β=-0.145, P = 0.08).

CONCLUSIONS

Self-reported PF was associated with better cardiometabolic and mental health in perimenopausal women. The IFIS might be proposed as an inexpensive, quick, and easy tool in clinical settings.

Evidence for improved systemic and local vascular function after long-term passive static stretching training of the musculoskeletal system

KEY POINTS

Vascular function and arterial stiffness are important markers of cardiovascular health and cardiovascular co-morbidity. Transitional phases of hypoemia and hypermia, with consequent fluctuations in shear rate, occuring during repetitive passive stretching adminstration (passive stretching training) may constitute an effective stimulus to induce an amelioration in vascular function, arterial stiffness and vascular remodelling by improving central and local blood flow control mechanisms. Vascular function, arterial stiffness and vascular remodelling were evaluated before and after 12 weeks of passive stretching training and after 6 weeks from training cessation, in the femoral, popliteal (treated with stretching), and brachial arteries (untreated) of both sides. After passive stretching training, vascular function and arterial remodelling improved, and arterial stiffness decreased in all the arteries, suggesting modifications of both central and local blood flow control mechanisms. Passive stretching-induced improvements related to central mechanisms seemed to have a short duration, as they returned to pre-training baseline within 6 weeks from training cessation, whereas those more related to a local mechanism persisted in the follow-up.

ABSTRACT

Acute passive stretching (PS) effects on blood flow ( Q ̇ ), shear rate ( Y ̇ ), and vascular function in the feeding arteries of the stretched muscle have been extensively investigated; however, few data are available on vascular adjustments induced by long-term PS training. We investigated the effects of PS training on vascular function and stiffness of the involved (femoral and popliteal) and uninvolved (brachial) arteries. Our hypothesis was that PS-induced changes in Q ̇ and Y ̇ would improve central and local mechanisms of Q ̇ control. Thirty-nine participants were randomly assigned to bilateral PS (n = 14), monolateral PS (n = 13) or no PS training (n = 12). Vascular function was measured before and after 12 weeks of knee extensor and plantar flexor muscles' PS training by single passive limb movement and flow-mediated dilatation (FMD). Central (carotid-femoral artery PWV, PWV_CF ) and peripheral (carotid-radial artery PWV, PWV_CR ) arterial stiffness was measured by pulse-wave velocity (PWV), together with systolic (SBP) and diastolic (DBP) blood pressure. After PS training, increases of 30%, 25% and 8% (P < 0.05) in femoral Δ Q ̇ , popliteal and brachial artery FMD%, respectively, occurred in both PS training groups. A decrease in PWV_CF , PWV_CR , SBP and DBP (-25%, -17%, -4% and -8%, respectively; P < 0.05) was noted. No changes occurred in controls. Vascular function improved and arterial stiffness reduced in the arteries involved and uninvolved with PS training, suggesting modifications in both central and local Q ̇ control mechanisms. PS-induced improvements had a short duration in some of vascular function parameters, as they returned to baseline within 6 weeks of PS training cessation.

Heart and musculoskeletal hemodynamic responses to repetitive bouts of quadriceps static stretching

The role of sympathetic and parasympathetic activity in relation to the repetitive exposure to static stretching (SS) on heart and musculoskeletal hemodynamics in stretched and resting muscles is still a matter of debate. The aim of the study was to determine cardiac and musculoskeletal hemodynamics to repetitive bouts of unilateral SS. Sympathetic and parasympathetic activity contribution to the central hemodynamics and local difference in circulation of stretched and resting muscles were also investigated. In eight participants, heart rate (HR), cardiac output (CO), mean arterial pressure (MAP), HR variability (HRV), blood pressure variability (BPV), and blood flow in passively stretched limb (SL) and control (CL, resting limb) were measured during five bouts of unilateral SS (45 s of knee flexion and 15 s of knee extension). SS increased sympathetic (~20%) and decreased parasympathetic activity (~30%) with a prevalence of parasympathetic withdrawal. During SS, HR, CO, and MAP increased by ~18 beats/min, ~0.29 l/min, ~12 mmHg, respectively. Peak blood flow in response to the first stretching maneuver increased significantly (+377 ± 95 ml/min) in the SL and reduced significantly (-57 ± 48 ml/min) in the CL. This between-limb difference in local circulation response to SS disappeared after the second SS bout. These results indicate that heart hemodynamic responses to SS are primarily influenced by the parasympathetic withdrawal rather than by the increase in sympathetic activity. The balance between neural and local factors contributing to blood flow regulation was affected by the level of SS exposure, likely associated with differences in the bioavailability of local vasoactive factors throughout the stretching bouts.NEW & NOTEWORTHY Repetitive exposure to static stretching (SS) on heart and musculoskeletal hemodynamics in stretched and remote muscles may be influenced by neural and local factors. We documented that SS-induced heart hemodynamic responses are primarily influenced by parasympathetic withdrawal. The balance between neural and local factors contributing to the regulation of musculoskeletal hemodynamics is dependent on SS exposure possibly because of different local vasoactive factor bioavailability during the subsequent stretching bouts.

Physical Fitness and Body Composition in Women with Systemic Lupus Erythematosus

Background and objectives: Higher physical fitness is associated with a more favorable weight and body composition in the general population, although this association has not been studied in patients with systemic lupus erythematosus (SLE). The aim of the present study was to examine the association of different components of physical fitness with body composition in women with SLE with mild disease activity. Materials and Methods: This cross-sectional study included 77 women with SLE (43.2 ± 13.8 years old) and clinical stability during the previous 6 months. Body composition (including body mass index (BMI), fat mass index (FMI), waist circumference, waist-to-height ratio and waist-to-hip ratio) was assessed using a stadiometer, an anthropometric tape, and a bioimpedance device. Physical fitness included cardiorespiratory fitness (Siconolfi step test and 6 min walk test), muscular strength (handgrip strength test as upper body measure and 30 s chair stand as lower body measure), and flexibility (back-scratch test). Participants with a fitness level equal or above the median of the study sample were categorized as "fit" and those below the median were categorized as "unfit". Linear regression assessed the association of physical fitness with body composition parameters. Results: Cardiorespiratory fitness and upper body muscular strength were negatively associated with BMI, FMI, waist circumference, and waist-to-height ratio (all, p < 0.05). Lower body muscular strength and flexibility were negatively related to FMI, waist circumference, waist-to-height ratio, and waist-to-hip ratio (all, p < 0.05). These relationships were still significant after controlling for age, disease duration, accrual damage, and SLE activity. Overall, fit patients presented significantly lower values in all body composition parameters compared to unfit patients (all, p < 0.05). Conclusions: The main findings of the present study suggest that physical fitness is inversely associated with body composition in women with SLE. Given the cross-sectional nature of this study, future clinical trials should study the causal pathways underlying these relationships.

Mechanistic insights into the modulatory role of the mechanoreflex on central hemodynamics using passive leg movement in humans

The aim of this study was to examine the independent contributions of joint range of motion (ROM), muscle fascicle length (MFL), and joint angular velocity on mechanoreceptor-mediated central cardiovascular dynamics using passive leg movement (PLM) in humans. Twelve healthy men (age: 23 ± 2 yr, body mass index: 23.7 kg/m2) performed continuous PLM at various randomized joint angle ROMs (0°-50° vs. 50°-100° vs. 0°-100°) and joint angular velocities ("fast": 200°/s vs. "slow": 100°/s). Measures of heart rate (HR), cardiac output (CO), and mean arterial pressure (MAP) were recorded during baseline and during 60 s of PLM. MFL was calculated from muscle architectural measurements of fascicle pennation angle and tissue thickness (Doppler ultrasound). Percent change in MFL increased across the transition of PLM from 0° to 50° (15 ± 3%; P < 0.05) and from 0° to 100° knee flexion (27 ± 4%; P < 0.05). The average peak percent change in HR (increased, approx. +5 ± 2%; P < 0.05), CO (increased, approx. +5 ± 3%; P < 0.05), and MAP (decreased, approx. -2 ± 2%; P < 0.05) were similar between fast versus slow angular velocities when compared against shorter absolute joint ROMs (i.e., 0°-50° and 50°-100°). However, the condition that exhibited the greatest angular velocity in combination with ROM (0°-100° at 200°/s) elicited the greatest increases in HR (+13 ± 2%; P < 0.05) and CO (+12 ± 2%; P < 0.05) compared with all conditions. Additionally, there was a significant relationship between MFL and HR within 0°-100° at 200°/s condition ( r2 = 0.59; P < 0.05). These findings suggest that increasing MFL and joint ROM in combination with increased angular velocity via PLM are important components that activate mechanoreflex-mediated cardioacceleration and increased CO. NEW & NOTEWORTHY The mechanoreflex is an important autonomic feedback mechanism that serves to optimize skeletal muscle perfusion during exercise. The present study sought to explore the mechanistic contributions that initiate the mechanoreflex using passive leg movement (PLM). The novel findings show that progressively increasing joint angle range of motion and muscle fascicle length via PLM, in combination with increased angular velocity, are important components that activate mechanoreflex-mediated cardioacceleration and increase cardiac output in humans.

Association between Resting Heart Rate and Health-Related Physical Fitness in Brazilian Adolescents

The aim of this study was to identify the relationship between health-related physical fitness components (aerobic fitness, muscle strength, flexibility, and body fat) and resting heart rate (RHR) in Brazilian adolescents. The study included 695 schoolchildren (14-19 years) from public schools of the city of São José, Brazil. RHR was evaluated using an automated oscillometric sphygmomanometer. Aerobic fitness was assessed by the modified Canadian Aerobic Fitness Test; muscle strength was measured by handgrip dynamometer; flexibility was assessed by the sit-and-reach test; and body fat was assessed indirectly by sum of two skinfold thicknesses (triceps and subscapular). Sociodemographic variables, habitual physical activity, sexual maturation, and body mass index were the covariates. Cardiorespiratory fitness (β = -0.11; 95%CI: -0.14, -0.08) and handgrip strength (β = -0.10; 95%CI: -0.18, -0.01) were inversely associated with RHR in boys. For girls, cardiorespiratory fitness (β = -0.09; 95%CI: -0.12, -0.06) was inversely associated with RHR. In both sexes, body fat (β = 0.50; 95%CI: 0.25, 0.75 for boys; β = 0.17; 95%CI: 0.36, 2.72 for girls) was directly associated with RHR. The RHR is measured more easily than the physical fitness tests, so it is recommended to assess adolescent's heath in large surveillance systems.

Association of objectively measured physical activity and sedentary time with arterial stiffness in women with systemic lupus erythematosus with mild disease activity

OBJECTIVES

To examine the association of objectively measured physical activity (PA) intensity levels and sedentary time with arterial stiffness in women with systemic lupus erythematosus (SLE) with mild disease activity and to analyze whether participants meeting the international PA guidelines have lower arterial stiffness than those not meeting the PA guidelines.

METHODS

The study comprised 47 women with SLE (average age 41.2 [standard deviation 13.9]) years, with clinical and treatment stability during the 6 months prior to the study. PA intensity levels and sedentary time were objectively measured with triaxial accelerometry. Arterial stiffness was assessed through pulse wave velocity, evaluated by Mobil-O-Graph® 24h pulse wave analysis monitor.

RESULTS

The average time in moderate to vigorous PA in bouts of ≥10 consecutive minutes was 135.1±151.8 minutes per week. There was no association of PA intensity levels and sedentary time with arterial stiffness, either in crude analyses or after adjusting for potential confounders. Participants who met the international PA guidelines did not show lower pulse wave velocity than those not meeting them (b = -0.169; 95% CI: -0.480 to 0.143; P = 0.280).

CONCLUSIONS

Our results suggest that PA intensity levels and sedentary time are not associated with arterial stiffness in patients with SLE. Further analyses revealed that patients with SLE meeting international PA guidelines did not present lower arterial stiffness than those not meeting the PA guidelines. Future prospective research is needed to better understand the association of PA and sedentary time with arterial stiffness in patients with SLE.