Daily Passive Muscle Stretching Improves Flow-Mediated Dilation of Popliteal Artery and 6-minute Walk Test in Elderly Patients with Stable Symptomatic Peripheral Artery Disease

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.

Impact of Exercise on Vascular Function in Middle-Aged and Older Adults: A Scoping Review

There is a substantial literature gap related to the vascular response to different types of exercise training in middle-aged and older populations. Thus, this scoping review aimed to examine the outcomes of controlled trials testing the long-term effects of exercise interventions on vascular function-related outcomes in middle-aged and older populations. The literature search was conducted following PRISMA guidelines. Data sources: five databases were used (EBSCO, MEDLINE, Web of Science, Science Direct, and Google Scholar). Eligibility criteria: controlled trials, published in the last 10 years, in English, containing well-described exercise interventions, reporting vascular quantitative effects of exercise in middle-aged and older people. A total of 62 publications were included. The studies included distinct types and intensities of exercise and were heterogeneous in volume and frequency. The assessed vascular outcomes also presented considerable variability. Overall, most studies reported positive effects of exercise on vascular function outcomes, regardless of exercise characteristics. Different exercise interventions can be applied to improve vascular function in middle-aged and older adults. Studies on combined and stretching exercises reported encouraging results in improving vascular function. Stretching exercises rise as an effective alternative in promoting vascular function among older adults, while combined exercise delivered promising vascular benefits in both populations.

Microvascular Adaptations to Muscle Stretch: Findings From Animals and the Elderly

Microcirculation in skeletal muscle is disturbed with advancing aging, causing limited capillary blood flow and exercise incapacity. Muscle stretch has been widely performed in physical therapy, sports medicine, and health promotion. However, the effect of stretch on microvascular reactivity and muscle blood flow remains unknown. This review focuses on stretch-induced microvascular adaptations based on evidence from cultured cells, small animals, and human studies. Vascular endothelium senses and responds to mechanical stimuli including stretch. This endothelial mechanotransduction potentially plays a vital role in the stretch-induced microvascular adaptation alongside hypoxia. Aging impairs microvascular endothelial function, but muscle stretch has the potential to restore it. Muscle stretch may be an alternative to improve vascular function and enhance exercising blood flow, especially for those who have difficulties in participating in exercise due to medical, functional, or psychological reasons.

Regular exercise ball training reduces arterial stiffness in sedentary middle-aged males

[Purpose] Reports suggest that static stretching, which improves body flexibility, could reduce arterial stiffness. Regular training using an exercise ball would increase flexibility in a different manner, compared to that from static stretching; however, it remains unclear whether such exercise can reduce arterial stiffness. This study aimed to clarify the effect of exercise ball training on arterial stiffness in sedentary middle-aged participants. [Participants and Methods] Fifteen healthy middle-aged males (age, 52 ± 12 years) were divided into a control group (n=7, CON) and an intervention group (n=8, INT). The CON group did not alter physical activity levels throughout the study period, while the INT group participated in supervised training sessions using an exercise ball for 20-30 min, 5 days/week, for a duration of 4 weeks. [Results] Exercise ball training significantly increased the sit-and-reach test score (CON, -3.8 ± 11.1% vs. INT, 33.8 ± 47.5%) and reduced cardio-ankle vascular index (CON, -0.8 ± 4.1% vs. INT, -5.7 ± 4.1%) and heart-ankle pulse wave velocity (CON, 1.6 ± 4.5% vs. INT, -4.2 ± 4.6%), as an index of arterial stiffness. [Conclusion] Four weeks of supervised training using an exercise ball as well as regular static stretching would increase body flexibility and reduce systemic arterial stiffness among sedentary middle-aged males.

Supervised Exercise Therapy Using Mobile Health Technology in Patients With Peripheral Arterial Disease: Pilot Randomized Controlled Trial

Background

Mobile health interventions are intended to support complex health care needs in chronic diseases digitally, but they are mainly targeted at general health improvement and neglect disease-specific requirements. Therefore, we designed TrackPAD, a smartphone app to support supervised exercise training in patients with peripheral arterial disease.

Objective

This pilot study aimed to evaluate changes in the 6-minute walking distance (meters) as a primary outcome measure. The secondary outcome measures included changes in physical activity and assessing the patients’ peripheral arterial disease–related quality of life.

Methods

This was a pilot two-arm, single-blinded, randomized controlled trial. Patients with symptomatic PAD (Fontaine stage IIa/b) and access to smartphones were eligible. Eligible participants were randomly assigned to the study, with the control group stratified by the distance covered in the 6-minute walking test using the TENALEA software. Participants randomized to the intervention group received usual care and the mobile intervention (TrackPAD) for the follow-up period of 3 months, whereas participants randomized to the control group received routine care only. TrackPAD records the frequency and duration of training sessions and pain levels using manual user input. Clinical outcome data were collected at the baseline and after 3 months via validated tools (the 6-minute walk test and self-reported quality of life). The usability and quality of the app were determined using the Mobile Application Rating Scale user version.

Results

The intervention group (n=19) increased their mean 6-minute walking distance (83 meters, SD 72.2), while the control group (n=20) decreased their mean distance after 3 months of follow-up (–38.8 meters, SD 53.7; P=.01). The peripheral arterial disease–related quality of life increased significantly in terms of “symptom perception” and “limitations in physical functioning.” Users’ feedback showed increased motivation and a changed attitude toward performing supervised exercise training.

Conclusions

Besides the rating providing a valuable support tool for the user group, the mobile intervention TrackPAD was linked to a change in prognosis-relevant outcome measures combined with enhanced coping with the disease. The influence of mobile interventions on long-term prognosis must be evaluated in the future.

Trial Registration

ClinicalTrials.gov NCT04947228; https://clinicaltrials.gov/ct2/show/NCT04947228

Is Stretching Exercise An Adequate Control Group in Clinical Trials Aimed at Improving Physical Fitness and Function of Older Adults? A Systematic Review and Meta-Analysis

This study aimed to determine if stretching exercise can be implemented as an adequate control therapy in exercise randomized controlled trials aimed at improving physical fitness and physical function in older adults. Five electronic databases were systematically searched for randomized controlled trials focused in the physical fitness and function of older adults using stretching exercise as control group. The methodological quality was assessed and a meta-analysis was carried out. Sixteen studies were included, 13 in the meta-analysis. The methodological quality ranged from fair to good. The meta-analysis only in the controls resulted in significant improvements in different functional parameters related to walking, balance, knee flexion strength, or global physical function. The interventions, compared with the controls, significantly improved balance and knee strength parameters. Stretching exercise as control therapy in older people can lead to beneficial effects and could influence the interpretation of the effect size in the intervention groups.

Effects of stretching exercises on human gait: a systematic review and meta-analysis

Background: Stretching is commonly used in physical therapy as a rehabilitation tool to improve range of motion and motor function. However, is stretching an efficient method to improve gait, and if so, for which patient category? Methods: A systematic review of randomized and non-randomized controlled trials with meta-analysis was conducted using relevant databases. Every patient category and every type of stretching programs were included without multicomponent programs. Data were meta-analysed where possible. Estimates of effect sizes (reported as standard mean difference (SMD)) with their respective 95% confidence interval (95% CI) were reported for each outcome. The PEDro scale was used for the quality assessment. Results: Twelve studies were included in the analysis. Stretching improved gait performance as assessed by walking speed and stride length only in a study with a frail elderly population, with small effect sizes (both SMD= 0.49; 95% CI: 0.03, 0.96; PEDro score: 3/10). The total distance and the continuous walking distance of the six-minute walking test were also improved only in a study in an elderly population who had symptomatic peripheral artery disease, with large effect sizes (SMD= 1.56; 95% CI: 0.66, 2.45 and SMD= 3.05; 95% CI: 1.86, 4.23, respectively; PEDro score: 5/10). The results were conflicting in healthy older adults or no benefit was found for most of the performance, spatiotemporal, kinetic and angular related variables. Only one study (PEDro score: 6/10) showed improvements in stance phase duration (SMD=-1.92; 95% CI: -3.04, -0.81), swing phase duration (SMD=1.92; 95 CI: 0.81, 3.04), double support phase duration (SMD= -1.69; 95% CI: -2.76, -0.62) and step length (SMD=1.37; 95% CI: 0.36, 2.38) with large effect sizes. Conclusions: There is no strong evidence supporting the beneficial effect of using stretching to improve gait. Further randomized controlled trials are needed to understand the impact of stretching on human gait.

Effects of stretching exercises on human gait: a systematic review and meta-analysis

Background: Stretching is commonly used in physical therapy as a rehabilitation tool to improve range of motion and motor function. However, is stretching an efficient method to improve gait, and if so, for which patient category? Methods: A systematic review of randomized and non-randomized controlled trials with meta-analysis was conducted using relevant databases. Every patient category and every type of stretching programs were included without multicomponent programs. Data were meta-analysed where possible. Estimates of effect sizes (reported as standard mean difference (SMD)) with their respective 95% confidence interval (95% CI) were reported for each outcome. The PEDro scale was used for the quality assessment. Results: Twelve studies were included in the analysis. Stretching improved gait performance as assessed by walking speed and stride length only in a study with a frail elderly population, with small effect sizes (both SMD= 0.49; 95% CI: 0.03, 0.96; PEDro score: 3/10). The total distance and the continuous walking distance of the six-minute walking test were also improved only in a study in an elderly population who had symptomatic peripheral artery disease, with large effect sizes (SMD= 1.56; 95% CI: 0.66, 2.45 and SMD= 3.05; 95% CI: 1.86, 4.23, respectively; PEDro score: 5/10). The results were conflicting in healthy older adults or no benefit was found for most of the performance, spatiotemporal, kinetic and angular related variables. Only one study (PEDro score: 6/10) showed improvements in stance phase duration (SMD=-1.92; 95% CI: -3.04, -0.81), swing phase duration (SMD=1.92; 95 CI: 0.81, 3.04), double support phase duration (SMD= -1.69; 95% CI: -2.76, -0.62) and step length (SMD=1.37; 95% CI: 0.36, 2.38) with large effect sizes. Conclusions: There is no strong evidence supporting the beneficial effect of using stretching to improve gait. Further randomized controlled trials are needed to understand the impact of stretching on human gait.

The Efficacy of Stretching Exercises on Arterial Stiffness in Middle-Aged and Older Adults: A Meta-Analysis of Randomized and Non-Randomized Controlled Trials

Background: Aerobic exercise is known to reduce arterial stiffness; however, high-intensity resistance exercise is associated with increased arterial stiffness. Stretching exercises are another exercise modality, and their effect on arterial stiffness remains unclear. The purpose of this study was to determine whether stretching exercises reduce arterial stiffness in middle-aged and older adults, performing the first meta-analysis of currently available studies. Methods: We searched the literature for randomized controlled trials (RCTs) and non-RCTs published up to January 2020 describing middle-aged and older adults who participated in a stretching intervention vs. controls without exercise training. The primary and secondary outcomes were changes in arterial stiffness and vascular endothelial function and hemodynamic status. Pooled mean differences (MDs) and standard MDs (SMDs) with 95% confidence intervals (CIs) between the intervention and control groups were calculated using a random effects model. Results: We identified 69 trials and, after an assessment of relevance, eight trials, including a combined total of 213 subjects, were analyzed. Muscle stretching exercises were shown to significantly reduce arterial stiffness and improve vascular endothelial function (SMD: −1.00, 95% CI: −1.57 to −0.44, p = 0.0004; SMD: 1.15, 95% CI: 0.26 to 2.03, p = 0.01, respectively). Resting heart rate (HR) and diastolic blood pressure (DBP) decreased significantly after stretching exercise intervention (MD: −0.95 beats/min, 95% CI: −1.67 to −0.23 beats/min, p = 0.009; MD: −2.72 mm Hg, 95% CI: −4.01 to −1.43 mm Hg, p < 0.0001, respectively) Conclusions: Our analyses suggest that stretching exercises reduce arterial stiffness, HR, and DBP, and improve vascular endothelial function in middle-aged and older adults.

Acute mitochondrial antioxidant intake improves endothelial function, antioxidant enzyme activity, and exercise tolerance in patients with peripheral artery disease

The results of this study reveal for the first time that acute oral intake of mitochondrial-targeted antioxidant (MitoQ, 80 mg) is effective for improving vascular endothelial function and superoxide dismutase in patients with peripheral artery disease (PAD). Acute MitoQ intake is also effective for improving maximal walking capacity and delaying the onset of claudication in patients with PAD. These findings suggest that the acute oral intake of MitoQ-mediated improvements in vascular mitochondria play a pivotal role for improving endothelial function, the redox environment, and skeletal muscle performance in PAD.