Cardiorespiratory Responses Research Articles

Cardiorespiratory Response to Six-Minute Step Test in Post COVID-19 Patients-A Cross Sectional Study.

New coronavirus disease 2019 (COVID-19) can cause persistent symptoms and physical weakness that can lead to a limitation in activities of daily living (ADL). There is a lack of evidence about the performance in the six-minute step test (6MST) of post-COVID-19 patients and healthy subjects. The aim of this study is to investigate the cardiorespiratory response induced by the 6MST in post-COVID-19 patients and compare it with the response of the six-minute walk test (6MWT). This cross-sectional study was conducted on 34 post-COVID-19 patients and 33 healthy subjects. The assessment was performed at one month from a non-severe SARS-CoV-2 infection. Both groups were assessed by using the 6MST, 6MWT, and the pulmonary function test (PFT). Post COVID functional status (PCFS) scale was used for the post-COVID-19 group to assess functional status. Physiological responses; heart rate (HR), respiratory rate (RR), oxygen saturation (SpO2), blood pressure (BP), and Borg scale for fatigue and dyspnea were recorded before and after the 6MST and 6MWT. the performance of the post-COVID-19 group was worse than the healthy group in both tests. In 6MWT, the distance walked by the post-COVID-19 group (423 ± 7) was 94 m less than the healthy group, and the number of climbed steps in the 6MST (121 ± 4) was 34 steps less than the healthy group. Both results were statistically significant (p < 0.001). There was a moderate positive correlation between the 6MST and 6MWT in walked distance versus steps number (r = 0.5, p < 0.001). In addition, there was a moderate correlation between the two tests in the post (HR, RR, SpO2, systolic blood pressure SBP, diastolic blood pressure DBP, dyspnea, and fatigue) with p < 0.001. Six-minute step tests produced similar cardiorespiratory responses when compared to a 6MWT. The 6MST can be used as an assessment tool for COVID-19 patients to evaluate their functional capacity and ADL.

Axial reloading during body weight unloading: Relationship between g-level and cardiorespiratory responses to running – A case study

ObjectiveProlonged microgravity exposure induces physiological de-conditioning that is partially mitigated by aerobic exercise. De-conditioning is also anticipated during partial gravity habitation (e.g., Moon or Mars). However, the relationship between gravity, resultant running speed, associated biomechanics, and the cardiorespiratory response is unknown. Thus, this case study evaluated responses to self-selected running across a continuum of simulated gravity levels generated by bodyweight unloading and axial loading via the Mk III Gravity Loading Countermeasure SkinSuit (GLCS). MethodsA healthy male ran at a self-selected speed for 5 min at six simulated gravity (Gz) levels. Bodyweight suspension unloaded the subject's mass to simulate Martian (0.38Gz) and Lunar (0.16Gz) gravity, whilst the GLCS reloaded the subject by 0.8Gz, thereby simulating 1.8Gz and 0.96Gz – comparable to 1Gz. Gait kinematics, heart rate (HR), respiratory variables, subjective ratings were evaluated in the final minute of each run and evaluated across conditions. ResultsCardiorespiratory, biomechanical and subjective responses were broadly similar in 1Gz and 0.96Gz (GLCS + Lunar). Positive linear associations were observed between Gz and minute ventilation (VE) oxygen consumption (VO2) and cost of transport responses to self-selected running, where HR responses correlated with self-selected running speed only. ConclusionRespiratory and biomechanical responses (but not HR) to self-selected running appear related to simulated Gz. Significance: Mk III GLCS is able to induce broadly G-equivalent biomechanical and cardiorespiratory responses, and thus may be a tool to facilitate g-dependence research and hypogravity exercise.

Ventilatory Limitation in Patients with HFpEF and Obesity: The Balance Between Increased Ventilatory Demand vs. Reduced Ventilatory Capacity

Study Objective: Patients with heart failure with preserved ejection fraction (HFpEF) have an increased ventilatory demand during exertion. Whether ventilatory capacity can meet this increased demand is unknown, especially in those with obesity. Hypothesis: We hypothesized that ventilatory capacity would be reduced in patients with HFpEF due to age- and obesity-related mechanical ventilatory constraints. Methodology: Body composition (DEXA) and pulmonary function were measured in 20 patients with invasively confirmed HFpEF (69±6yr; 9M/11W). Cardiorespiratory responses, breathing mechanics, and arterial blood gases were measured at rest, during exercise at 20 W, and at peak exercise. Based upon inspection of resting forced vital capacity (FVC, L) values, the patients were grouped into those with an FVC&lt;3L (n=12; 2M/10W) and those with an FVC&gt;3.8L (n=8; 7M/1W). Differences between the two groups were compared using independent t-tests. Comparisons were not made between conditions (rest, 20W, &amp; peak exercise). Results: Percent body fat was greater in the FVC&lt;3L group (51% vs. 38%, p&lt;0.01). Ventilatory demand (V̇ E /V̇CO 2 ) was equally elevated in both groups at rest and during exercise. FVC was 2 L less in the FVC&lt;3L group (79±14 vs. 100±13 %predicted) and maximal voluntary ventilation was approximately 50 L/min less (p&lt;0.01). All lung volume subdivisions (L) were significantly lower in the FVC&lt;3L group at rest and during exercise (p&lt;0.05). End expiratory lung volume (L) was higher during exercise in both groups as many of the patients had expiratory flow limitation at rest and during exercise (&gt;50% V T at peak exercise). End inspiratory lung volume (L) approached 90% of total lung capacity in both groups, thus V T (%FVC) expansion was limited in both groups. The FVC&lt;3L group was not able to increase V̇ E (L/min) enough to lower arterial CO 2 at peak exercise as much as the FVC&gt;3.8L group (40±4 vs 35±3; p&lt;0.05). Peak V̇O 2 (%predicted) was approximately 22% less (p&lt;0.05) in the FVC&lt;3L group. Ratings of perceived breathlessness and unpleasantness were higher in the FVC&lt;3L group at 20 W (p&lt;0.05). Conclusion: Ventilatory capacity is limited in patients with HFpEF and obesity; this is particularly true for patients who have a small or reduced FVC. We propose that quantifying ventilatory limitations in patients with HFpEF is critical to establishing whether they can meet the challenges of an elevated ventilatory demand and whether these limitations may play a role in provoking exertional dyspnea and exercise intolerance. This research was supported by the National Institutes of Health (1P01HL137630), King Foundation, Cain Foundation, and Texas Health Presbyterian Hospital Dallas. B.N. Balmain is supported by an American Heart Association Fellowship (grant number: 826064). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The effect of acute oral pyridoxine supplementation on peripheral chemoreflex sensitivity in human hypertension

ATP has been identified as an important signalling molecule in the carotid body. Animal models of hypertension have uncovered that ATP transmission via purinergic (P2) receptors increases carotid body tonicity and sensitivity, which drives sympathetic outflow and elevates blood pressure. A naturally occurring metabolite of pyridoxine (Vitamin B6), namely pyridoxal-5-phosphate, is a non-selective P2X receptor antagonist. In this study we tested the hypothesis that oral administration of pyridoxine reduces peripheral chemoreflex sensitivity and blood pressure in human hypertension. 14 treated hypertensive patients (4 men, 71±5 yr, 27±6 kg·m -2 , 156±19/83±8 mmHg) completed a double-blind placebo-controlled crossover study with either oral pyridoxine (600 mg) or placebo. Two-hours later, minute ventilation (V̇ E ), end-tidal partial pressures of oxygen and carbon dioxide (P ET O 2 and P ET CO 2 ), mean arterial pressure (MAP), and heart rate (HR) were recorded during an isocapnic hypoxic rebreathing protocol (target P ET O 2 45mmHg). Cardiorespiratory responses were taken as the change from baseline to peak rebreathing (final 15s). Arterial oxygen saturation (S a O 2 ) was calculated from P ET O 2 using the Severinghaus equation, and peripheral chemoreflex sensitivity taken as ΔV̇ E divided by ΔS a O 2 . Baseline V̇ E (13.02±3.26 vs. 12.68±4.13 L·min -1 , P=0.616), MAP (109±11 vs. 104±10 mmHg, P=0.058), and HR (63±11 vs. 62±8 BPM, P=0.463), were not different between pyridoxine and placebo conditions, respectively. The ΔV̇ E response to isocapnic hypoxia tended to be blunted with pyridoxine compared to placebo (6.88±3.94 vs. 9.87±7.69 L·min -1 ; P=0.188), but this did not reach statistical significance. Similarly, peripheral chemoreflex sensitivity was not different with pyridoxine compared to placebo (-0.46±0.31 vs. -0.64±0.49 L·min -1 ·% -1 , P=0.148). However, individuals with a higher peripheral chemoreflex sensitivity in the placebo condition, displayed a more marked reduction in peripheral chemoreflex sensitivity following pyridoxine (R 2 =0.63, P=0.005). While HR and MAP increased during isocapnic hypoxia (both P&lt;0.001), the magnitude of this response did not differ with pyridoxine or placebo administration. In this preliminary study, oral pyridoxine lowered neither blood pressure nor peripheral chemoreflex sensitivity in human hypertension. However, oral pyridoxine did lower peripheral chemoreflex sensitivity in those hypertension patients in whom baseline peripheral chemoreflex sensitivity (i.e., placebo condition) was highest. It is possible that oral pyridoxine supplementation may be beneficial for those hypertensive patients who exhibit overactivation of their peripheral chemoreflex. Health Research Council of New Zealand (Ref# 19/687), the University of Auckland Faculty Research Development Fund, and the New Zealand Lottery Grants Board (R-LHR-2021-153114). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Chronic Vagotomy Alters Glutamate Transmission in the Nucleus Tractus Solitarii (nTS)

The nTS is the first site of integration and processing of sensory afferent information and is one of the crucial brainstem nuclei involved in cardiorespiratory reflexes. This nucleus receives afferent information from many visceral structures in the thorax and abdomen via the peripheral branches of the vagus nerve. Vagal afferents release glutamate (Glu) which initiates signaling processes that leads to chemo- and baroreflex-mediated changes in sympathetic and phrenic nerve activity. Previous studies by us have shown that decreasing afferent input via unilateral vagotomy augmented nTS astrocyte complexity. Astrocytes contribute to regulation of Glu concentration by removing Glu from the synaptic cleft via excitatory amino acid transporters (EAATs). We hypothesized that vagotomy attenuates Glu signaling in the nTS due to increased Glu uptake by greater EAAT expression or function. Surgical transection or sham surgery of the right cervical vagus nerve caudal to the nodose ganglion was performed in male Sprague-Dawley rats. One week after surgery, mean arterial pressure (MAP), heart rate (HR), and splanchnic sympathetic and phrenic nerve activity (SSNA and PhrNA) were recorded in anesthetized and ventilated rats. Intact vagus nerves and the right phrenic nerve were acutely transected. Nanoinjections of Glu (30 nl, 1-10 mM) into the nTS decreased MAP, HR, SSNA and PhNA in both sham and vagotomy groups. Vagotomy blunted the HR, SSNA and PhrNA responses, indicating that Glu signaling was attenuated. To determine if increased EAAT function contributed to blunted Glu responses, the EAAT blocker TFB-TBOA (10nM, 60nl) was nanoinjected into the nTS. EAAT blockade mimicked the effect of Glu, producing similar depressor, bradycardic, and apneic responses in both groups. TBOA also enhanced the cardiorespiratory responses to Glu injection in both groups. EAAT blockade did not restore Glu responses in the vagotomy group compared to sham. Taken together, these data suggest that increased EAAT function did not account for the attenuated Glu signaling in the nTS. Further studies are needed to uncover the mechanisms by which vagotomy affects Glu signaling in the nTS. NIH R01 HL098602 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Exploring the Effect of Yoga on Exercise Endurance As Assessed by Cardiorespiratory Efficiency Tests in Exercise Physiology Laboratory: A Pilot Study.

Background Today's world of cut-throat competition is boggling with stress as the most common problem among the modern generation, and reduction in stress demands a radical solution. Yoga comes as a rescuer that focuses on improving one's physical and spiritual well-being. It can increase one's strength and flexibility. Yoga practitioners have asserted the effect of physical exercise involved in it on balancing physical and spiritual health for decades, but only recently has there been a move to substantiate these claims through research. This study aimed at assessing the effect of yogic practice on exercise endurance and physical fitness as assessed by important physical fitness parameters through cardiorespiratory efficiency tests in an Exercise Physiology Laboratory. Methodology A total of 60 Bachelor of Medicine, Bachelor of Surgery (MBBS) studentsfrom a rural medical college in central India were recruited for the study.Thirty MBBS students who had undergone yogic training for six months comprised the trained or the case group, and another group of 30 students comprising the untrained group were recruited for the study from different levels of the course within the age group of 17-25 years. Body mass index (BMI) and body surface area (BSA) were calculated. Resting pulse rate and blood pressure, resting respiratory rate, maximal oxygen consumption (VO2max), physical fitness index (PFI), breath holding time (BHT), and 40 mm Hg endurance test time was measured. Results The mean PFI (%) in males was 88.82±5.56 and 96.05±7.44, and that in females was 82.06±8.95 and 96.55±6.47 in the control and case groups, respectively. The mean 40 mm Hg endurance test (in seconds) in males was 36.47±8.45 and 48.88±8.64 and in females was 29.79±10.30 and 38.4±10.69 in the control and test groups, respectively. The mean BHT (in seconds) in males was 44.80±14.18 and 58.91±12.35, and that in females was 42.29±15.37 and 54.60±13.36 as in controland case groups, respectively. The VO2max evaluated by the modified Harvard step test was 2.41±0.58 L/min in control males and 3.6±0.90 L/min in the case group of males, and it was 2.14±0.49 L/min in the control group of females, and 3.76±0.69 L/min in case group of females. Conclusion By studying the dynamics of the various cardiorespiratory responses, we have determined the values of fitness parameters in the case group. It was found that the yoga group had statistically significantly higher VO2 max per minute and better PFI, BHT, and 40 mm Hg endurance values (p<0.05).

Physiological Responses of Anemic Women to Exercise under Hypoxic Conditions

When combining two conditions of reduced oxygen availability, anemia and hypoxia, human physiological responses are highly challenged to maintain arterial oxygen delivery, especially during whole-body exercise. The aim of this study was to compare the cardiorespiratory responses of mildly anemic women with those of healthy controls, while cycling in normobaric hypoxia. Two groups of young females were matched for age, weight, height, and involvement in physical activity, one with normal hemoglobin, hematocrit, and ferritin levels and another suffering from mild iron deficiency anemia (10 &lt; (Hb) &lt; 12 g/dL, 34 &lt; Hct &lt; 37%, ferritin &lt; 15 μg/L). They cycled to exhaustion under normoxia and hypoxia (FIO2 0.21 and 0.14), and their physiological responses were compared at 40, 80, and 100% VO2max of the specific condition. The two groups differed (p &lt; 0.05) mainly at the higher exercise intensities; the anemic participants exhibited similar heart rate but lower oxygen pulse than their control counterparts, as well as a larger drop in maximal oxygen uptake. However, they sustained maximal effort by employing the anaerobic metabolism to a larger extent, which stimulated a greater ventilatory response. It appears that iron deficiency anemia of mild severity, which is commonly observed in young athletic females, impacts physiological responses during whole-body exercise in the presence of moderate hypoxia.

Venous capacity and compliance in hypertensive adults: influence of hypoxia and hyperoxia.

In hypertension, the cardiorespiratory responses to peripheral chemoreflex activation (hypoxia) and inactivation (hyperoxia) are reportedly augmented, but the impact on peripheral venous function is unknown. We tested the hypothesis that in hypertensives, both hypoxia and hyperoxia evoke more pronounced changes in lower limb venous capacity and compliance, than in age-matched normotensives. In 10 hypertensive [HTN: 7 women; age: 71.7 ± 3.7 yr, mean blood pressure (BP): 101 ± 10 mmHg, mean ± SD] and 11 normotensive (NT: 6 women; age: 67.7 ± 8.0 yr, mean BP 89 ± 11 mmHg) participants, great saphenous vein cross-sectional area (GSV CSA; Doppler ultrasound) was measured during a standard 60 mmHg thigh cuff inflation-deflation protocol. Separate conditions of room air, hypoxia [fraction of inspired oxygen ([Formula: see text]): 0.10] and hyperoxia ([Formula: see text]: 0.50) were tested. In HTN, GSV CSA was decreased in hypoxia (5.6 ± 3.7 mm2, P = 0.041) compared with room air (7.3 ± 6.9 mm2), whereas no change was observed with hyperoxia (8.0 ± 9.1 mm2, P = 0.988). In NT, no differences in GSV CSA were observed between any condition (P = 0.299). Hypoxia enhanced GSV compliance in HTN (-0.0125 ± 0.0129 vs. -0.0288 ± 0.0090 mm2·100 mm2·mmHg-1, room air vs. hypoxia, respectively; P = 0.004), but it was unchanged in NT (-0.0139 ± 0.0121 vs. -0.0093 ± 0.0066 mm2·100 mm2·mmHg-1, room air vs. hypoxia, respectively; P < 0.541). Venous compliance was unaltered with hyperoxia in both groups (P < 0.05). In summary, compared with NT, hypoxia elicits a decrease in GSV CSA and enhanced GSV compliance in HTN, indicating enhanced venomotor responsiveness to hypoxia.NEW & NOTEWORTHY Hypertension remains a significant global health problem. Although hypertension research and therapies are keenly focused on the heart and arterial circulation, the venous circulation has been neglected comparatively. We determined whether hypoxia, known to cause peripheral chemoreflex activation, evoked more pronounced changes in lower limb venous capacity and compliance in hypertensives (HTN) than in age-matched normotensives (NT). We found that hypoxia reduced venous capacity in the great saphenous vein in HTN and increased its compliance twofold. However, hypoxia did not affect venous function in NT. Our data indicate the venomotor response to hypoxia is enhanced in hypertension, and this may contribute to the hypertensive state.

Acute Cardiovascular and Cardiorespiratory Effects of JWH-018 in Awake and Freely Moving Mice: Mechanism of Action and Possible Antidotal Interventions?

JWH-018 is the most known compound among synthetic cannabinoids (SCs) used for their psychoactive effects. SCs-based products are responsible for several intoxications in humans. Cardiac toxicity is among the main side effects observed in emergency departments: SCs intake induces harmful effects such as hypertension, tachycardia, chest pain, arrhythmias, myocardial infarction, breathing impairment, and dyspnea. This study aims to investigate how cardio-respiratory and vascular JWH-018 (6 mg/kg) responses can be modulated by antidotes already in clinical use. The tested antidotes are amiodarone (5 mg/kg), atropine (5 mg/kg), nifedipine (1 mg/kg), and propranolol (2 mg/kg). The detection of heart rate, breath rate, arterial oxygen saturation (SpO2), and pulse distention are provided by a non-invasive apparatus (Mouse Ox Plus) in awake and freely moving CD-1 male mice. Tachyarrhythmia events are also evaluated. Results show that while all tested antidotes reduce tachycardia and tachyarrhythmic events and improve breathing functions, only atropine completely reverts the heart rate and pulse distension. These data may suggest that cardiorespiratory mechanisms of JWH-018-induced tachyarrhythmia involve sympathetic, cholinergic, and ion channel modulation. Current findings also provide valuable impetus to identify potential antidotal intervention to support physicians in the treatment of intoxicated patients in emergency clinical settings.

Time-of-Day Effects of Exercise on Cardiorespiratory Responses and Endurance Performance-A Systematic Review and Meta-Analysis.

Kang, J, Ratamess, NA, Faigenbaum, AD, Bush, JA, Finnerty, C, DiFiore, M, Garcia, A, and Beller, N. Time-of-day effects of exercise on cardiorespiratory responses and endurance performance-A systematic review and meta-analysis. J Strength Cond Res XX(X): 000-000, 2022-The time-of-day effect of exercise on human function remains largely equivocal. Hence, this study aimed to further analyze the existing evidence concerning diurnal variations in cardiorespiratory responses and endurance performance using a meta-analytic approach. Literature search was conducted through databases, including PubMed, CINAHL, and Google Scholar. Article selection was made based on inclusion criteria concerning subjects' characteristics, exercise protocols, times of testing, and targeted dependent variables. Results on oxygen uptake (V̇o2), heart rate (HR), respiratory exchange ratio, and endurance performance in the morning (AM) and late afternoon or evening (PM) were extracted from the chosen studies. Meta-analysis was conducted with the random-effects model. Thirty-one original research studies that met the inclusion criteria were selected. Meta-analysis revealed higher resting V̇o2 (Hedges' g = -0.574; p = 0.040) and resting HR (Hedges' g = -1.058; p = 0.002) in PM than in AM. During exercise, although V̇o2 remained indifferent between AM and PM, HR was higher in PM at submaximal (Hedges' g = -0.199; p = 0.046) and maximal (Hedges' g = -0.298; p = 0.001) levels. Endurance performance as measured by time-to-exhaustion or the total work accomplished was higher in PM than in AM (Hedges' g = -0.654; p = 0.001). Diurnal variations in V̇o2 appear less detectable during aerobic exercise. The finding that exercising HR and endurance performance were greater in PM than in AM emphasizes the need to consider the effect of circadian rhythm when evaluating athletic performance or using HR as a criterion to assess fitness or monitor training.

Which field test should be used to compare the functional exercise capacities of patients with type 2 diabetes mellitus with and without diabetic peripheral neuropathy? Cross-sectional study

BackgroundThe 6-minute step test (6MST) has begun to be used as a simple and effective alternative for assessing functional exercise capacity. There is no study using 6MSTs to evaluate the exercise capacities of patients with type 2 diabetes mellitus (DM) with and without diabetic peripheral neuropathy (DPN). ObjectiveTo compare the cardiorespiratory responses of the 6-minute walk test (MWT) and the 6MST exercise tests and to analyze the usability of the 6MST in Type 2 DM patients with and without neuropathy. Methods32 non-neuropathic Type 2 DM, 32 neuropathic Type 2 DM patients, and 30 healthy volunteers were included in this cross-sectional study. Functional exercise capacity was evaluated with the 6MWT and the 6MST. The 30-second sit-stand test (30s STS) was used to evaluate general lower extremity muscle strength and function. ResultsThere was a significant difference in the results of 6MWT (m), 6MST (number of steps), and 30s STS of the three groups (p<0.05). The 6MST results of patients with neuropathic Type 2 DM were significantly lower than those of non-neuropathic diabetics and those who were healthy (number of steps; 114.07±25.57 vs. 133.48±33.57 vs. 160.35±28.52, respectively) (p=0.001). The change in cardiorespiratory response in systolic blood pressure, heart rate, perceived dyspnea, and leg fatigue severity was significantly higher at 6MST than 6MWT in the three groups (p<0.05). 6MST was correlated with 6MWT (r=0.679, p=0.001), and 30s STS (r=0.589, p=0.001) in patients with Type 2 DM. ConclusionsCardiorespiratory responses increased more in 6MST compared to 6MWT. In patients with Type 2DM, 6MWT and 6MST were moderately correlated with each other. 6MST is an effective and safe assessment method that may better reveal the differences in functional exercise capacity between neuropathic and non-neuropathic individuals in clinics.

Effects of exercise training parameters on cardiorespiratory fitness of individuals with type 2 diabetes mellitus: a systematic review and meta-analysis.

To assess the effects of exercise training parameters on cardiorespiratory fitness of individuals with type 2 diabetes mellitus (T2DM). This systematic review was registered on PROSPERO (CRD42020210470). Searches were performed on PubMed, PEDro EMBASE, MEDLINE (Ovid), LILACS, PsycINFO, SCIELO, CINAHL, and Cochrane Library. The primary outcome was cardiorespiratory fitness, defined as maximal oxygen uptake (VO2max) during a maximal or submaximal exercise test. Two independent reviewers extracted data and assessed the risk of bias. Data were pooled using a random effects model and expressed as mean difference (MD) and 95% confidence interval (95%CI). Heterogeneity (I2) was assessed using Cochran's Q test. The risk of bias and quality of evidence was assessed using the Cochrane risk of bias tool and GRADE. Twenty-two studies comparing exercise and control groups were included. The risk of bias indicated some concerns in most studies, and the quality of evidence was rated very low. Interventions with moderate (MD = 1.91, 95%CI = .58 to 3.34) and progressive exercise intensity (MD = 2.70, 95%CI = 2.43 to 2.96) and volume (MD = 1.72, 95%CI = .59 to 2.85) showed greater improvements in VO2max. Protocols that progressively increased exercise training parameters improved the cardiorespiratory fitness response. Progressive exercise might be more suitable for individuals with T2DM. Our conclusion may be limited due to the very low quality of evidence. The online version contains supplementary material available at 10.1007/s40200-023-01205-5.

Short-Term Effect of Bariatric Surgery on Cardiorespiratory Response at Submaximal, Ventilatory Threshold, and Maximal Exercise in Women with Severe Obesity.

People with obesity have varying degrees of cardiovascular, pulmonary, and musculoskeletal dysfunction that affect aerobic exercise testing variables. Short time after bariatric surgery, these dysfunctions could affect both peak oxygen consumption ([Formula: see text] O2 peak), the gold standard for assessing cardiorespiratory fitness (CRF) and aerobic capacity evaluated with ventilatory threshold (VT1). The purpose of this study was to evaluate the short-term effect of bariatric surgery, i.e. before the resumption of physical activity, on submaximal, at VT1 and maximal cardiorespiratory responses in middle-aged women with severe obesity. Thirteen middle-aged women with severe obesity (age: 36.7 ± 2.3years; weight: 110.5 ± 3.6kg, BMI: 41.8 ± 1.1kg/m2) awaiting bariatric surgery participated in the study. Four weeks before and 6 to 8weeks after surgery, body composition was determined by bioelectrical impedance. The participants performed an incremental cycling test to [Formula: see text] O2 peak. After bariatric surgery, all body composition parameters were reduced, absolute [Formula: see text] O2 peak and peak workload decline with a lower VT1. Relative [Formula: see text] O2 at peak and at VT1 (ml/min/kg or ml/min/kg of FFM) remained unchanged. Ventilation was lower after bariatric surgery during exercise with no change in cardiac response. Our results showed that weight loss alone at short-term after bariatric surgery decreased CRF as seen by a decrease in absolute [Formula: see text] O2 peak, and peak workload with lower VT1, whereas relative [Formula: see text] O2 (ml/min/kg or ml/min/kg of FFM) during exercise remained unchanged in women with obesity. Rapid FFM loss affects cardiorespiratory responses at submaximal and maximal.

Which field test should be used to compare the functional exercise capacities of patients with type 2 diabetes mellitus with and without diabetic peripheral neuropathy? Cross-sectional study

BackgroundThe 6-minute step test (6MST) has begun to be used as a simple and effective alternative for assessing functional exercise capacity. There is no study using 6MSTs to evaluate the exercise capacities of patients with type 2 diabetes mellitus (DM) with and without diabetic peripheral neuropathy (DPN). ObjectiveTo compare the cardiorespiratory responses of the 6-minute walk test (MWT) and the 6MST exercise tests and to analyze the usability of the 6MST in Type 2 DM patients with and without neuropathy. Methods32 non-neuropathic Type 2 DM, 32 neuropathic Type 2 DM patients, and 30 healthy volunteers were included in this cross-sectional study. Functional exercise capacity was evaluated with the 6MWT and the 6MST. The 30-second sit-stand test (30s STS) was used to evaluate general lower extremity muscle strength and function. ResultsThere was a significant difference in the results of 6MWT (m), 6MST (number of steps), and 30s STS of the three groups (p<0.05). The 6MST results of patients with neuropathic Type 2 DM were significantly lower than those of non-neuropathic diabetics and those who were healthy (number of steps; 114.07±25.57 vs. 133.48±33.57 vs. 160.35±28.52, respectively) (p=0.001). The change in cardiorespiratory response in systolic blood pressure, heart rate, perceived dyspnea, and leg fatigue severity was significantly higher at 6MST than 6MWT in the three groups (p<0.05). 6MST was correlated with 6MWT (r=0.679, p=0.001), and 30s STS (r=0.589, p=0.001) in patients with Type 2 DM. ConclusionsCardiorespiratory responses increased more in 6MST compared to 6MWT. In patients with Type 2DM, 6MWT and 6MST were moderately correlated with each other. 6MST is an effective and safe assessment method that may better reveal the differences in functional exercise capacity between neuropathic and non-neuropathic individuals in clinics.

Cardio-Respiratory and Muscle Oxygenation Responses to Submaximal and Maximal Exercise in Normobaric Hypoxia: Comparison between Children and Adults.

As differential physiological responses to hypoxic exercise between adults and children remain poorly understood, we aimed to comprehensively characterise cardiorespiratory and muscle oxygenation responses to submaximal and maximal exercise in normobaric hypoxia between the two groups. Following familiarisation, fifteen children (Age = 9 ± 1 years) and fifteen adults (Age = 22 ± 2 years) completed two graded cycling exercise sessions to exhaustion in a randomized and single-blind manner in normoxia (NOR; FiO2 = 20.9) and normobaric hypoxia (HYP; FiO2 = 13.0) exercises conditions. Age-specific workload increments were 25 W·3 min-1 for children and 40 W·3 min-1 for adults. Gas exchange and vastus lateralis oxygenation parameters were measured continuously via metabolic cart and near-infrared spectroscopy, respectively. Hypoxia provoked significant decreases in maximal power output PMAX (children = 29%; adults 16% (F = 39.3; p < 0.01)) and power output at the gas exchange threshold (children = 10%; adults:18% (F = 8.08; p = 0.01)) in both groups. Comparable changes were noted in most respiratory and gas exchange parameters at similar power outputs between groups. Children, however, demonstrated, lower PETCO2 throughout the test at similar power outputs and during the maintenance of V˙CO2 at the maximal power output. These data indicate that, while most cardiorespiratory responses to acute hypoxic exercise are comparable between children and adults, there exist age-related differential responses in select respiratory and muscle oxygenation parameters.

Assessment of exercise capacity using field walking tests in patients after the Fontan procedure: A case–control study

BackgroundDespite the frequent use of the 6-minute walk test (6MWT), exercise capacity has not been assessed with the incremental shuttle walk test (ISWT) in patients who have undergone the Fontan procedure. It is unclear whether these tests cause clinically relevant cardiorespiratory responses in these patients. ObjectivesWe aimed to assess cardiorespiratory responses to the 6MWT and ISWT in Fontan patients, compare the responses with those in the controls, and examine the agreement between the two field tests. MethodsSubmaximal exercise capacity was assessed using the 6MWT, maximal exercise capacity using the ISWT, quadriceps isometric muscle strength with a hand dynamometer, and body composition using a bioelectrical impedance device. ResultsTwenty-one Fontan patients (16.42±6.63 years, 5F/16M) and 21 controls (16.57±4.30 years, 7F/14M) were included. While body composition was similar between the groups (p>0.05), quadriceps isometric muscle strength and 6MWT and ISWT distance were lower in the Fontan patients than in the controls (p<0.05). In both the 6MWT and ISWT, pre- and post-test heart rate (HR), oxygen saturation (SpO2), dyspnea, and leg fatigue differed significantly between the Fontan patients and the controls (p<0.05). In addition, the ISWT resulted in a more significant change in HR, SpO2, and leg fatigue than the 6MWT in the Fontan patients (p<0.05). Bland–Altman plots for the 6MWT vs. the ISWT indicated agreement between the two tests. ConclusionThere were remarkable changes in HR, SpO2, dyspnea, and leg fatigue in both tests. With similar safety to the 6MWT but with more caution applied for adverse events, the ISWT can also be performed as a field test to evaluate exercise capacity and identify more pronounced exercise-induced responses (especially oxygen desaturation) in Fontan patients.

The effect of transcutaneous electrical stimulation of the submental area on the cardiorespiratory response in normal and awake subjects.

Background: Electrical stimulation has recently been introduced to treat patients with Obstructive sleep apnoea There are, however, few data on the effects of transcutaneous submental electrical stimulation (TES) on the cardiovascular system. We studied the effect of TES on cardiorespiratory variables in healthy volunteers during head-down-tilt (HDT) induced baroreceptor loading. Method: Cardiorespiratory parameters (blood pressure, heart rate, respiratory rate, tidal volume, airflow/minute ventilation, oxygen saturation, and end-tidal CO2/O2 concentration) were recorded seated, supine, and during head-down-tilt (50) under normoxic, hypercapnic (FiCO2 5%) and poikilocapnic hypoxic (FiO2 12%) conditions. Blood pressure (BP) was measured non-invasively and continuously (Finapres). Gas conditions were applied in random order. All participants were studied twice on different days, once without and once with TES. Results: We studied 13 healthy subjects (age 29 (12) years, six female, body mass index (BMI) 23.23 (1.6) kg·m-2). A three-way ANOVA indicated that BP decreased significantly with TES (systolic: p = 4.93E-06, diastolic: p = 3.48E-09, mean: p = 3.88E-08). Change in gas condition (systolic: p = 0.0402, diastolic: p = 0.0033, mean: p = 0.0034) and different postures (systolic: 8.49E-08, diastolic: p = 6.91E-04, mean: p = 5.47E-05) similarly impacted on BP control. When tested for interaction, there were no significant associations between the three different factors electrical stimulation, gas condition, or posture, except for an effect on minute ventilation (gas condition/posture p = 0.0369). Conclusion: Transcutaneous electrical stimulation has a substantial impact on the blood pressure. Similarly, postural changes and variations in inspired gas impact on blood pressure control. Finally, there was an interaction between posture and inspired gases that affects minute ventilation. These observations have implications on our understanding of integrated cardiorespiratory control, and may prove beneficial for patients with SDB who are assessed for treatment with electrical stimulation.

The effect of robot-assisted walking in different modalities on cardiorespiratory responses and energy consumption in patients with subacute stroke

ABSTRACT Objectives The aim of our study was to evaluate the effect of robot-assisted walking in different modalities on cardiorespiratory responses and energy consumption in subacute stroke patients. Methods Our study consisted of 16 individuals between the ages of 18–65 years. Individuals diagnosed with hemiplegia after unilateral ischemic or haemorrhagic stroke constitute the stroke group. Eight subacute stroke individuals were included in the experimental group, and eight healthy individuals were included in the control group. Each participant tested on the Lokomat in three consecutive days in random sequence, with three tests: the first test: 100% guiding strength (GF)and 100% body weight support (BWS); the second test 80% GF, 50% BWS; the third test 60% GF, 30% BWS was achieved. Gas analyzer (Cosmed, Quark CPET, Italy) measurements were made with the help of a mask to evaluate the cardiorespiratory responses of the participants during all tests. Results In the comparison of the three test results of the two groups separately, the stroke group’s oxygen consumption (VO2), carbon dioxide production (VCO2), tidal volume (VT), pulse reserve (HRR), calories burned per hour (EEh), Borg dyspnea values, control group’s VO2, VCO2, VE, HR, HRR, and EEh, Borg values were statistically significantly different (p < 0.005). It was seen that the third test results were significantly greater than the first and second test results (p < 0.005). Discussion By decreasing GF and BWS values during robot-assisted walking, adequate cardio-metabolic and energy response in both subacute stroke patients and healthy individuals could be achieved. These results show us that it is important to consider the cardiorespiratory function of the patient when choosing training protocols.

Functional capacity testing in patients with pulmonary hypertension (PH) using the one-minute sit-to-stand test (1-min STST).

The one-minute sit-to-stand-test (1-min STST) is a quick, space saving test to evaluate functional capacity. Exercise testing plays an important role in the long-term follow-up of pulmonary hypertension (PH) patients and is currently evaluated using the six-minute-walk-test (6MWT). The aim of the study was to assess the convergent validity of the 1-min STST in patients with PH and its association with markers of PH severity. We evaluated 106 PH patients with the 1-min-STST and 6MWT and measured cardiorespiratory parameters (heart rate, blood pressure, oxygen saturation) before and after test conduction. N-terminal pro brain-type natriuretic peptide (NT-proBNP), WHO functional class (WHO-FC) and mean pulmonary artery pressure (mPAP) were defined as markers of PH severity. Strong correlation was found between performances of 1-min STST and 6MWT (r = .711, p < .001), indicating convergent validity. Both tests were inversely associated with NT-proBNP (STST: r = -.405, p < .001; 6MWT: r = -.358, p < .001), WHO-FC (STST: r = -.591, p < .001; 6MWT: r = -.643, p < .001) and mPAP (STST: r = -.280, p < .001; 6MWT: r = -.250, p < .001). Significant changes in cardiorespiratory parameters were observed in both tests (all p < 0.001). Further the post-exercise cardiorespiratory parameters correlated strongly between the 1-min STST and 6MWT (all r ≥ .651, all p < .001). The 1-min STST demonstrated good convergent validity with the 6MWT and was associated with markers of PH severity. Furthermore, both exercise tests caused similar cardiorespiratory responses.

Hip Hop Party Dance: Cardiorespiratory Profile and Responses to a Predefined Sequence.

Hip hop is a popular dance genre practiced worldwide that has gained popularity since the 1970s. Despite this, studies related to the area and its physiological demands are still scarce. The purpose of this study was to report the cardiorespiratory profile of a group of male and female hip hop dancers to determine the zones of intensity of a predefined hip hop party dance sequence. Eight Brazilian professional hip hop dancers, four women and four men, mean age 22 ± 2.3 years, participated in the study. Using a portable gas analyser (Cosmed K5) their cardiorespiratory variables were measured at two different times: first, during a maximal treadmill test and later during a predefined hip hop party dance sequence. Descriptive statistics (mean and standard deviation) were used for calculating the dependent variables: oxygen consumption (VO2), heart rate (HR), and the intensity zones for the predefined hip hop sequence. Data normality was verified using the Shapiro-Wilk test. The Mann-Whitney U-test was performed to check any sex-related difference (p < 0.01). No statistical difference between male and female dancers was found in the cardiorespiratory profile and responses to the predefined hip hop party dance sequence. On the treadmill, the participants' VO2peak was 57.3 ± 12.7 ml·kg-1·min-1, and HRmax was 190.0 ± 9.1 b·min-1. The predefined hip hop party dance sequence was mainly (61%) performed in the moderate aerobic zone. However, when the dancers jumped, the intensity of the sequence increased. This information could be used to develop a specific supplementary training protocols for hip hop dancers to improve their physiological fitness parameters and reduce the incidence of injury.