Min Of Recovery Research Articles

Oxyhemoglobin Concentration and Oxygen Uptake Signal During Recovery From Exhaustive Exercise in Healthy Subjects-Relationship With Aerobic Capacity.

This proof of concept study is dedicated to the quantification of the short-term recovery phase of the muscle oxygenation and whole-body oxygen uptake kinetics following an exhaustive cycling protocol. Data of 15 healthy young participants (age 26.1 ± 2.8 years, peak oxygen uptake 54.1 ± 5.1 mL∗min-1∗kg-1) were recorded during 5 min cool down-cycling with a power output of 50 W on an electro-magnetically braked cycle ergometer. The oxygen uptake (VO2) signal during recovery was modeled by exponential function. Using the model parameters, the time (T1/2) needed to return VO2 to 50% of VO2peak was determined. The Hill’s model was used to analyze the kinetics of oxyhemoglobin concentration (Sm, %), non-invasively recorded by near-infrared spectroscopy (NIRS) over the M. vastus lateralis. Analysis of the Pearson correlation results in statistically significant negative relationships between T1/2 and relative VO2peak (r = −0.7). Relevant significant correlations were determined between constant defining the slope of VO2 decrease (parameter B) and the duration of the anaerobic phase (r = −0.59), as well as between Hill’s coefficient and average median Smmax for the final 2 min of recovery. The high correlation between traditional variables commonly used to represent the cardio-metabolic capacity and the parameters of fits from exponential and Hill models attests the validity of our approach. Thus, proposed descriptors, derived from non-invasive NIRS monitoring during recovery, seem to reflect aerobic capacity. However, the practical usefulness of such modeling for clinical or other vulnerable populations has to be explored in studies using alternative testing protocols.

Comparison of sprint interval and continuous endurance training on oxidative stress and antioxidant adaptations in young healthy adults

Background: Different intensities of exercise induce varying levels of reactive oxygen species, causing oxidative stress. However, regular physical training enhances the antioxidant system and protects tissues by oxidative stress. This study aimed to investigate the difference in markers between time-efficient low-volume high intensity interval (sprint interval training: SIT) and traditional high-volume low-intensity methods (continuous endurance training: CET) regarding oxidative stress and antioxidant levels. Material and methods: Fifteen male volunteers were divided into two groups according to their VO2max levels. The SIT program consisted of 4–6 Wingate all-out sprints with a 4.5 min recovery, while CET consisted of 30–50 min cycling at 60% VO2max for seven weeks. Total oxidant status (TOS), total antioxidant status (TAS), plasma malondialdehyde (MDA) and glutathione peroxidase (GSH-Px) levels were examined in pre and post-intervention. Results: Increases in GSH-Px (30% vs. 55%), TOS (33% vs. 18%) and a significant decrease in MDA (8.6%, p<0.003; 6.8%, p<0.016) in CET and SIT were observed, respectively. By contrast, TAS decreased (62%) after CET and increased (17%) after SIT. No significant differences in these parameters were reported after the training period between SIT and CET groups. Conclusions: SIT was suggested as a safe exercise model to improve general health and the performance of traditional CET.

Rice Husk-Derived Cellulose Nanofibers: A Potential Sensor for Water-Soluble Gases.

Cellulose and its derivatives have evoked much attention in sensor technology as host-matrices for conducting materials because of their versatility, renewability, and biocompatibility. However, only a few studies have dealt with the potential utilization of cellulose as a sensing material without a composite structure. In this study, cellulose nanofibers (CNF) and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibers (TOCNF) extracted from rice husks by using ultrasonic-assisted methods are introduced as a potential gas sensing material with highly sensitive performance. To fabricate nanocellulose-based films, CNF, TOCNF, and TOCNF with glycerol (TOCNF/G) were dispersed in water and applied on polyimide substrate with digital electrodes to form self-standing thin films by a drop-casting method. A transparent coating layer on the surface of the plate after drying is used for the detection of water-soluble gases such as acetone, ammonia, methane, and hydrogen sulfide gases at room temperature at 52% relative humidity. The sensor prototypes exhibited high sensitivity, and the detection limit was between 1 ppm and 5 ppm, with less than 10 min response and recovery time. The results indicate that both the CNF- and the TOCNF-coated sensors show good sensitivity toward ammonia and acetone, compared to other gases. A TOCNF/G-coated sensor exhibited minimum time in regard to response/recovery time, compared to a CNF-coated sensor. In this study, nanocellulose-based sensors were successfully fabricated using a low-cost process and a bio-based platform. They showed good sensitivity for the detection of various gases under ambient conditions. Therefore, our study results should further propel in-depth research regarding various applications of cellulose-based sensors in the future.

Urban mining in buildings for a circular economy: Planning, process and feasibility prospects

The construction industry remains under immense pressure to reduce its material and climate related impacts. Increasing material demand and reduced building lifetimes have therefore motivated efforts for urban mining in buildings. Even though urban mining has been projected as a crucial measure for improving resource efficiency, its adoption as a practice in the construction industry remains at a very symbolic stage. Upscaling secondary resource recovery and reuse in the construction sector requires further efforts to understand urban mining feasibility from the perspective of project timelines, salvage time, skills and costs. Hence, this study develops an empirical research approach to measure urban mining feasibility and applies it to demolition-ready urban residential buildings stock in Singapore with semi-skilled construction workers. It develops indicators for urban mining feasibility based on planning stages, process change, behavioural practices and reuse-driven economic considerations. Based on urban mining of over 350 building components from 34 categories, results show an average of 1 to 12 min recovery time with an estimated urban mining cost from S$0.8 to S$9 per building component. Further, regulatory requirements for demolition permits can provide sufficient time for urban mining without affecting project timelines. Even though the mining skills of workers seem important, results highlights significant improvement in mining skills based on repeated salvage of specific building components. Results also provide robust evidence of reuse-driven urban mining feasibility in the case under study with significant prospects for embodied carbon savings. Overall, urban mining of buildings can contribute to net-zero targets and climate mitigation efforts with greater multi-stakeholder involvement and market push for reuse in the construction sector.

Measures of excess dot{mathrm{V}} CO2 and recovery dot{mathrm{V}} CO2 as indices of performance fatigability during exercise: a pilot study

BackgroundThe severity of performance fatigability and the capacity to recover from activity are profoundly influenced by skeletal muscle energetics, specifically the ability to buffer fatigue-inducing ions produced from anaerobic metabolism. Mechanisms responsible for buffering these ions result in the production of excess carbon dioxide (CO2) that can be measured as expired CO2 ( dot{mathrm{V}} CO2) during cardiopulmonary exercise testing (CPET). The primary objective of this study was to assess the feasibility of select assessment procedures for use in planning and carrying out interventional studies, which are larger interventional studies investigating the relationships between CO2 expiration, measured during and after both CPET and submaximal exercise testing, and performance fatigability.MethodsCross-sectional, pilot study design. Seven healthy subjects (30.7±5.1 years; 5 females) completed a peak CPET and constant work-rate test (CWRT) on separate days, each followed by a 10-min recovery then 10-min walk test. Oxygen consumption ( dot{mathrm{V}} O2) and dot{mathrm{V}} CO2 on- and off-kinetics (transition constant and oxidative response index), excess- dot{mathrm{V}} CO2, and performance fatigability severity scores (PFSS) were measured. Data were analyzed using regression analyses.ResultsAll subjects that met the inclusion/exclusion criteria and consented to participate in the study completed all exercise testing sessions with no adverse events. All testing procedures were carried out successfully and outcome measures were obtained, as intended, without adverse events. Excess- dot{mathrm{V}} CO2 accounted for 61% of the variability in performance fatigability as measured by dot{mathrm{V}} O2 on-kinetic ORI (ml/s) (R2=0.614; y = 8.474x − 4.379, 95% CI [0.748, 16.200]) and 62% of the variability as measured by PFSS (R2=0.619; y = − 0.096x + 1.267, 95% CI [−0.183, −0.009]). During CPET, dot{mathrm{V}} CO2 -off ORI accounted for 70% (R2=0.695; y = 1.390x − 11.984, 95% CI [0.331, 2.449]) and dot{mathrm{V}} CO2 -off Kt for 73% of the variability in performance fatigability measured by dot{mathrm{V}} O2 on-kinetic ORI (ml/s) (R2=0.730; y = 1.818x − 13.639, 95% CI [0.548, 3.087]).ConclusionThe findings of this study suggest that utilizing dot{mathrm{V}} CO2 measures may be a viable and useful addition or alternative to dot{mathrm{V}} O2 measures, warranting further study. While the current protocol appeared to be satisfactory, for obtaining select cardiopulmonary and performance fatigability measures as intended, modifications to the current protocol to consider in subsequent, larger studies may include use of an alternate mode or measure to enable control of work rate constancy during performance fatigability testing following initial CPET.

47-OR: Acute Fluctuations in Plasma Glucose Affect Echocardiographic-Derived Measures of Systolic Function in Patients with Type 1 Diabetes

Insulin treatment in patients with type 1 diabetes (T1D) causes rapid and large fluctuations in plasma glucose (PG) concentrations, and patients with T1D and poor glycemic control have an increased risk of cardiovascular disease including heart failure. We evaluated echocardiographic changes in cardiac function during experimental hypoglycemia and rebound hyperglycemia in patients with T1D. Patients with T1D (age 52.8±11.4 years, HbA1c 7.5±0.8% [57.6±8.9 mmol/mol], BMI 25.7±3.1 kg/m2) underwent two clamp days in random order. Both clamp days included three steady-state phases: 1) a 45-min hyperinsulinemic euglycemic phase (PG=6 mmol/L); 2) a 60-min hyperinsulinemic hypoglycemic phase (PG=2.5 mmol/L), and 3) a 60-min recovery phase in either hyperglycemia or euglycaemia (Clamp A: PG: 20 mmol/L; Clamp B: PG: 6 mmol/L). Cardiac function was evaluated with echocardiography at each phase by a blinded observer. Acute hypoglycemia increased left ventricular ejection fraction (LVEF) (absolute change, Clamp A: 6.5% [5.0;8.1], P=0.0001; Clamp B: 6.2% [4.6;7.9], P<0.0001) and global longitudinal strain (GLS) (absolute change, Clamp A: -3.1% (-4.5;-1.6), P<0.001; Clamp B: -3.5% (-4.6;-2.3), P<0.0001) from baseline. In Clamp A during hyperglycemia, LVEF and GLS were increased compared to baseline euglycemia (5.0% [3.2;6.8] (P<0.0001) and 2.1% [-3.7;-0.6] (P<0.01), respectively). An increase in LVEF was also observed in the recovery phase in Clamp B despite normalization of PG for 60 min (2.1% [0.5;3.8], P<0.05). In the recovery phase, LVEF was greater during hyperglycemia in Clamp A (2.9% [1.0;4.7], P<0.01) compared to euglycaemia in Clamp B. In conclusion, our findings suggest that acute fluctuations in PG affect echocardiographic-derived measures of systolic function in patients with T1D. Disclosure C. R. Andreasen: None. F. K. Knop: Advisory Panel; Self; MSD Corporation, Novo Nordisk A/S, Sanofi, Consultant; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company, Novo Nordisk A/S, Pharmacosmos, Zealand Pharma A/S, Research Support; Self; Novo Nordisk A/S, Zealand Pharma A/S, Speaker’s Bureau; Self; AstraZeneca, Bayer AG, Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company, MSD Corporation, Novo Nordisk A/S. T. Vilsbøll: Consultant; Self; Amgen Inc., AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Bristol-Myers Squibb Company, Gilead Sciences, Inc., Lilly Diabetes, Merck Sharp & Dohme Corp., Mundipharma International, Novo Nordisk, Sanofi, Sun Pharmaceutical Industries Ltd. A. Andersen: None. P. G. Hagelqvist: None. K. U. Abelin: None. J. V. Lauritsen: None. P. G. Jørgensen: Speaker’s Bureau; Self; AstraZeneca. S. Engberg: None. J. J. Holst: Consultant; Self; Novo Nordisk, Other Relationship; Self; Antag Therapeutics, Bainan Biotech, MSD Corporation, Novo Nordisk, Other Relationship; Spouse/Partner; Antag Therapeutics, Bainan Biotech, Synklino ApS. U. Pedersen-bjergaard: Advisory Panel; Self; Novo Nordisk A/S, Sanofi-Aventis, Consultant; Self; Abbott, Speaker’s Bureau; Self; Novo Nordisk A/S. Funding Novo Nordisk Foundation (NNF17SA0031406)

Effect of Pre-Exercise Heat Pack Treatment on Markers of Muscle Damage After Resistance Exercise

PURPOSE: This study aimed to investigate the effect of pre-exercise heat pack treatment on muscle activity and markers of muscle damage after exercise-induced damage.METHODS: Ten healthy male university students were tested for 3 weeks. They were exposed to three conditions (non-warm-up exercise, warm-up exercise, and heat pack treatment) before exercise. The experiment was conducted at 1-week intervals for every participant. The warm-up exercise was performed by combining a modified active warm-up with a cycle ergometer and an isokinetic dynamometer. The main exercise, which modified the exercise-induced muscle damage protocol, was conducted by flexing and extending the knee joint using an isokinetic dynamometer. The heat pack treatment before the exercise involved moist heat application for 20 min.RESULTS: The changes in blood muscle fatigue markers and blood muscle damage markers were not significantly different between the groups (α>.05). However, significant differences were observed in the time immediately after exercise, 10-min recovery, 30-min recovery, and 60-min recovery (<i>p</i><.05). A statistically significant difference was observed in the change in pain in the heat pack treatment group (<i>p</i><.05).CONCLUSIONS: Heat pack treatment for 20 min before exercise did not minimize the muscle damage markers and fatigue markers following exercise-induced damage, but reduced immediate muscle soreness. Use of heat pack treatment was associated with a change in muscle activity and improvement in certain aspects of muscle soreness.

Does a short intervention with vibration foam roller recover lifeguards better after a water rescue? A pilot study.

The aim of this study was to analyze the effects of a recovery program based on foam roller with and without vibration on blood lactate clearance and perceived fatigue after a water rescue. A quasi-experimental crossover design was carried out to compare passive (PR) recovery and a short protocol of foam roller (FR) and vibration foam roller (VFR) recovery after a 100 m water rescue in 7 volunteer lifeguards. Blood lactate and perceived exertion were measured before and after the rescue, and also after the 5-min recovery intervention. Blood lactate levels decrease significantly with foam roller (p = 0.013; effect size = 0.97) and vibration foam roller recovery (p < 0.001; effect size = 1.62). Passive recovery did not show significant differences clearing out blood lactate. Fatigue perceived decrease significantly with all the recovery methods, but foam roller has higher effects on the global fatigue and VFR on the legs. FR and VFR clear out more blood lactate and decrease fatigue more than PR, with the subsequently increase of the physical conditioning to perform another effort.

Voluntary Cooling during Exercise Is Augmented in People with Multiple Sclerosis Who Experience Heat Sensitivity.

We tested the hypothesis that people with multiple sclerosis (MS) who experience heat sensitivity voluntarily engage in cool-seeking behavior during exercise to a greater extent than healthy controls. In a 27.0°C ± 0.2°C, 41% ± 2% RH environment, seven participants with relapsing-remitting MS who exhibited heat sensitivity and seven healthy controls completed two randomized trials cycling for 40 min (EX) at 3.5 W·kg-1 metabolic heat production, followed by 30 min recovery (REC). In one trial, participants were restricted from engaging in cooling (CON). In the other trial, participants voluntarily pressed a button to receive 2 min of ~2°C water perfusing a top (COOL). Mean skin and core temperatures and mean skin wettedness were recorded continuously. Total time in cooling provided an index of cool-seeking behavior. RPE, total symptom scores (MS only), and subjective fatigue (MS only) were recorded every 10 min. Core temperature (+0.5°C ± 0.1°C) and skin wettedness (+0.53 ± 0.02 a.u.) increased but were not different between groups or trials at end exercise (P = 0.196) or end recovery (P = 0.342). Mean skin temperature was reduced in COOL compared with CON at end exercise (P ≤ 0.002), with no differences between groups (P ≥ 0.532). MS spent more total time in cooling during EX (MS, 13 ± 3 min; healthy, 7 ± 4 min; P < 0.001) but not REC (MS, 2 ± 1 min; healthy, 0 ± 1 min; P = 0.496). RPE was greater at end exercise in MS (P = 0.001). Total symptom scores increased during exercise (P = 0.005) but was not different between trials (P = 0.321), whereas subjective fatigue was not attenuated in the cooling trial (P = 0.065). Voluntary cooling is augmented in MS but does not consistently mitigate perceptions of heat-related symptoms or subjective fatigue.

High-intensity Intermittent Training Enhances Spatial Memory and Hippocampal Neurogenesis Associated with BDNF Signaling in Rats.

High-intensity intermittent (or interval) training (HIIT) has started to gain popularity as a time-effective approach to providing beneficial effects to the brain and to peripheral organs. However, it still remains uncertain whether HIIT enhances hippocampal functions in terms of neurogenesis and spatial memory due to unconsidered HIIT protocol for rodents. Here, we established the HIIT regimen for rats with reference to human study. Adult male Wistar rats were assigned randomly to Control, moderate-intensity continuous training (MICT; 20m/min, 30min/day, 5 times/week), and HIIT (60m/min, 10 30-s bouts of exercise, interspaced with 2.5min of recovery, 5 times/week) groups. The ratios of exercise time and volume between MICT and HIIT were set as 6:1 and 2:1-4:1, respectively. After 4weeks of training, all-out time in the incremental exercise test was prolonged for exercise training. In skeletal muscle, the plantaris citrate synthase activity significantly increased only in the HIIT group. Simultaneously, both HIIT and MICT led to enhanced spatial memory and adult hippocampal neurogenesis (AHN) as well as enhanced protein levels of hippocampal brain-derived neurotrophic factor (BDNF) signaling. Collectively, we suggest that HIIT could be a time-efficient exercise protocol that enhances hippocampal memory and neurogenesis in rats and is associated with hippocampal BDNF signaling.

Age and Parity Effects in the Hypothalamic Pituitary Adrenal Axis’ Response to Multimodal Stress in Female Mice

The hypothalamic pituitary adrenal (HPA) axis responds to environmental perturbations to maintain homeostasis. Pregnancy demands extensive modifications in HPA axis function to prepare for increased energy and metabolic demands required to meet the needs of mother and offspring. Short-term effects of pregnancy on the HPA axis have been shown, but data is lacking regarding the long-term effects in middle-aged female mice no longer breeding. Since changes of the HPA axis are further found with age, in this study, we examined both parity- and age-related interactions on the HPA axis in female mice. Wildtype C57bl/6N females were divided into nulliparous young (NY) (3-6 mo) and nulliparous middle-aged (NM) or multiparous retired-breeder middle-aged (RBM) (8-10 mo) groups. RBM mice were killed at least 4 weeks after their last litter was weaned. Control mice were euthanized directly out of the home cage and experimental groups were euthanized at 0 min, 30 min, or 90 min recovery (n=8-10/ group) after 2h of multi-modal stress (MMS; restraint, noise, shaker, light). (Paraventricular nucleus of the hypothalamus (PVN) neuronal activity was quantified by c-FOS immunoreactivity (-ir), and plasma corticosterone (CORT) levels were measured by radioimmunoassay. Corticotropin releasing hormone (CRH) mRNA was assayed by in situ hybridization. Two-way ANOVA showed effects of age (p<0.0248), parity (p<0.0021), time (p<0.0001), and interaction (p<0.0009) on CORT levels. Specifically, basal CORT levels were reduced in NM/RBM versus NY mice. In all groups, CORT levels were significantly elevated by MMS. There was no difference between CORT levels immediately after MMS in NY or NM groups, but CORT levels after 30- and 90- min recovery from MMS remained elevated in NM, indicating reduced negative feedback with age. Additionally, RBM plasma CORT was further reduced in all time groups versus NM, accompanied by a return to baseline CORT after 90 min recovery, suggesting a parity-dependent effect on the HPA axis. Changes in CORT levels were correlated with c-FOS-ir. MMS increased PVN c-FOS-ir in all groups compared to controls and c-FOS-ir in NM was significantly greater than PVN c-FOS of RBM. Further, while c-FOS-ir in the NY females was reduced to baseline 30 min after MMS, the return to baseline was more gradual in NM. No effect of parity or age was seen in Crh mRNA. Collectively, our findings show that activation of the HPA axis in females involves interactions between age- and parity- dependent function. Our findings further show activation and inhibition of the HPA axis in females involving long-term changes that occur after pregnancy, which may increase risk for stress- or postpartum- related disorders. Supported by NIDDK 1-R01 DK105826

Acute and residual neuromuscular effects of displacement in indirect vibratory stimulation

The aim of this study was to evaluate the effect of indirect vibratory stimulation on different magnitudes of displacement on acute and residual neuromuscular responses. Fifteen healthy volunteers were randomly submitted to 3 experimental sessions, with intervals of 5 to 7 days (5 maximal voluntary contractions - MVC, 12 s of duration each and 5 min of recovery) between sessions. To determine the residual responses, the volunteers performed a MVC before and after each treatment for 12 s, with a 5-minute recovery. The experimental sessions were composed of isometric actions without vibrations (CONTROL) and two sessions of isometric actions with the addition of vibrations at 20 Hz and 3 mm (Sinusoidal Vibration A) and 5 mm (Sinusoidal Vibration B). Before and after each of the experimental sessions, an isometric evaluation without vibrations was performed. For the acute effect, it was verified that the addition of vibrations induced a facilitatory effect on the explosive strength variables (p < .05), independent of the type of studied displacement in relation to the control treatment. In short, it was verified that the addition of vibration induced an acute facilitating effect on the explosive strength. However, the induced effect was not persistent (residual effect) for the explosive strength.

Resting electrocardiographic differences in ventricular repolarization between children and young adults with congenital heart disease and those with a structurally normal heart are diminished by exercise.

Exercise-induced repolarization changes have not been systematically evaluated in children and young adults with congenital heart disease (CHD). We carried out this study to assess the QTc responses during exercise in children and young adults (≤ 21 years) with CHD with comparison to those with structurally normal hearts. Baseline QRS duration, calculated baseline QTc, QTc at 4 min of recovery and delta QTc was measured in 360 exercise stress tests which were performed in 360 subjects (137 stress tests in patients with CHD [CHD group] and 223 stress tests in patients with structurally normal hearts). The effects of presence of CHD and potential confounders on primary outcome measure, change in QTc (delta QTc), and secondary outcome measures (QTc at baseline and QTc at 4 min of recovery) were determined using multiple linear regression analyses. The baseline QTc and the QTc at 4 min of recovery in the CHD group was longer than patients with structurally normal hearts (respective p values=.00 and .001). No significant difference was noted in delta QTc between the CHD and structurally normal heart groups. While patients with CHD had a longer QRS duration and QTc interval at baseline than those with structurally normal hearts, these differences did not persist or augment with exercise.

The Animal Health Trust (1942–2020)

The significance of cardiac arrhythmias and their possible association with upper airway obstruction are frequently considered in the clinical investigation of poor performance. The specific aims of this retrospective study of a group of poorly performing Standardbred and Norwegian–Swedish Coldblooded trotters were to: (1) describe the overall frequency and frequency distributions of arrhythmias; (2) describe arrhythmia characteristics including percent prematurity, relative recovery cycle lengths and QRS morphology; (3) describe variability of normal RR intervals; and (4) explore possible associations between upper airway abnormalities and arrhythmia categories during peak exercise and recovery.The records of 103 trotters presented to the Norwegian University of Life Sciences for high-speed treadmill testing were reviewed. The occurrence of at least one arrhythmic event was high (77–78%) when considering all exercise periods and 6–10% prematurity criteria. Triplets, salvos, and/or paroxysmal tachyarrhythmias occurred in 8% of horses during peak exercise. Complex ventricular arrhythmias occurred in 15% of horses in the first 2 min of recovery. Evaluation of QRS morphology and return cycle lengths demonstrated areas of overlap in characteristics typically attributed to either supraventricular or ventricular arrhythmias. There was no association between airway diagnosis and arrhythmias during any exercise period. The maximum average HR during peak exercise was an excellent predicter for complex ventricular arrhythmias during recovery. Because perfect categorization of arrhythmias is not possible, future studies should report descriptive arrhythmia information. Prospective studies that evaluate various degrees of upper airway obstruction and the effect on known initiators of arrhythmogenesis are needed.

Spectral analysis of blood flow oscillations to assess the plantar skin blood flow regulation in response to preconditioning local vibrations.

Local vibration has shown promise in improving skin blood flow and wound healing. However, the underlying mechanism of local vibration as a preconditioning intervention to alter plantar skin blood flow after walking is unclear. The objective was to use wavelet analysis of skin blood flow oscillations to investigate the effect of preconditioning local vibration on plantar tissues after walking. A double-blind, repeated measures design was tested in 10 healthy participants. The protocol included 10-min baseline, 10-min local vibrations (100 Hz or sham), 10-min walking, and 10-min recovery periods. Skin blood flow was measured over the first metatarsal head of the right foot during the baseline and recovery periods. Wavelet amplitudes after walking were expressed as the ratio of the wavelet amplitude before walking. The results showed the significant difference in the metabolic (vibration 10.06 ±1.97, sham 5.78 ±1.53, p <0.01) and neurogenic (vibration 7.45 ±1.54, sham 4.78 ±1.22, p <0.01) controls. There were no significant differences in the myogenic, respiratory and cardiac controls between the preconditioning local vibration and sham conditions. Our results showed that preconditioning local vibration altered the normalization rates of plantar skin blood flow after walking by stimulating the metabolic and neurogenic controls.

Wearing compression tights post-exercise enhances recovery hemodynamics and subsequent cycling performance.

To investigate sports compression garment (CG)-induced recovery hemodynamics and their potential impact on subsequent cycling performance. In a randomized crossover design, 13 physically active men (20.9 ± 1.4years; 65.9 ± 7.8kg; 173.3 ± 4.8cm; peak power output 254.2 ± 27.2W) underwent 2 experimental trials. During each experimental trial, the subjects performed 20-min fatiguing preload cycling followed by 60-min passive recovery wearing either a sports CG (28.6 ± 9.4mmHg) or gymnastic pants (CON). A 5-min all-out cycling performance test was subsequently conducted and power output and cadence were recorded. Cardiac output (CO) and stroke volume (SV) were measured using Doppler ultrasound (USCOM®). Heart rate (HR), blood lactate [BLa-], ratings of perceived exertion (RPE), leg muscle soreness (LMS), mean arterial pressure (MAP) and systemic vascular resistance (SVR) were monitored at 5, 15, 30, 45, 60min during passive recovery. During the subsequent 5-min all-out cycling performance test, power output (215.2 ± 24.0 vs. 210.8 ± 21.5W, CG vs. CON) and cadence (72.5 ± 3.8 vs. 71.2 ± 4.8rpm, CG vs. CON) were higher in CG than CON (P < 0.05). SV was higher at 15, 30 and 45min (P < 0.05), CO was higher at 5 and 45min (P < 0.05), HR was lower at 15 and 30min (P < 0.05) and [BLa-] was lower at 5 and 15min (P < 0.05) during passive recovery, while LMS was lower at all time-points (P < 0.05) compared with CON. Sports CG improves subsequent cycling performance by enhancing hemodynamic responses and attenuating perceived muscle soreness during passive recovery in physically active men.

Evaluating cannabidiol (CBD) expectancy effects on acute stress and anxiety in healthy adults: a randomized crossover study

RationaleCannabidiol (CBD) has been reported to attenuate stress and anxiety, but little is known about the extent to which such effects result from pharmacological versus expectancy factors.ObjectivesWe evaluated whether CBD expectancy alone could influence stress, anxiety, and mood, and the extent to which beliefs regarding CBD effects predicted these responses.MethodsIn this randomized crossover study, 43 health adults (23 women) attended two experimental laboratory sessions, where they self-administered CBD-free hempseed oil sublingually. During one session, they were (incorrectly) informed that the oil contained CBD and in the other session, that the oil was CBD-free. Following administration, participants engaged in the Maastricht Acute Stress Test (MAST). Heart rate variability (HRV) was assessed continuously, and subjective state was assessed at baseline, 90-min following oil administration, immediately following the MAST, and after a 10-min recovery period.ResultsThe CBD expectancy condition was associated with increased sedation as well as with changes in HRV that were consistent with heightened anticipatory stress regulation. Overall, there were no systematic changes in subjective stress, or anxiety, according to expectancy condition. However, participants who endorsed strong a priori beliefs that CBD has anxiolytic properties reported significantly diminished anxiety in the CBD expectancy condition.ConclusionsCBD expectancy alone impacted several subjective and physiological responses. Additionally, expectancy-related factors were implicated in anxiolytic effects of CBD for those who believed it was helpful for such purposes, emphasizing the need to measure and control for CBD-related expectancies in clinical research that involves the administration of CBD.

Post-exercise cardiac autonomic and cardiovascular responses to heart rate-matched and work rate-matched hypoxic exercise

PurposeThis study investigated the effect of performing hypoxic exercise at the same heart rate (HR) or work rate (WR) as normoxic exercise on post-exercise autonomic and cardiovascular responses.MethodsThirteen men performed three interval-type exercise sessions (5 × 5-min; 1-min recovery): normoxic exercise at 80% of the WR at the first ventilatory threshold (N), hypoxic exercise (FiO2 = 14.2%) at the same WR as N (H-WR) and hypoxic exercise at the same HR as N (H-HR). Autonomic and cardiovascular assessments were conducted before and after exercise, both at rest and during active squat–stand manoeuvres (SS).ResultsCompared to N, H-WR elicited a higher HR response (≈ 83% vs ≈ 75%HRmax, p < 0.001) and H-HR a reduced exercise WR (− 21.1 ± 9.3%, p < 0.001). Cardiac parasympathetic indices were reduced 15 min after exercise and recovered within 60 min in N and H-HR, but not after H-WR (p < 0.05). H-WR altered cardiac baroreflex sensitivity (cBRS) both at rest and during SS (specifically in the control of blood pressure fall during standing phases) in the first 60 min after the exercise bout (p < 0.05). Post-exercise hypotension (PEH) did not occur in H-HR (p > 0.05) but lasted longer in H-WR than in N (p < 0.05).ConclusionsModerate HR-matched hypoxic exercise mimicked post-exercise autonomic responses of normoxic exercise without resulting in significant PEH. This may relate to the reduced WR and the limited associated mechanical/metabolic strain. Conversely, WR-matched hypoxic exercise impacted upon post-exercise autonomic and cardiovascular responses, delaying cardiac autonomic recovery, temporarily decreasing cBRS and evoking prolonged PEH.

Cardiorespiratory responses to acute bouts of high-intensity functional training and traditional exercise in physically active adults.

High-intensity functional training is a popular form of exercise, but little is known about how it compares to more traditional exercise patterns. Thirty healthy, physically active adults (15 males, 15 females) performed a high-intensity functional training workout (HIFT) and a traditional workout (TRAD). Cardiorespiratory responses were measured during and for 15 min after each workout. Peak heart rate (males: 187±7 vs. 171±10 bpm, P<0.001; females: 191±9 vs. 175±6 bpm, P<0.001), peak VO<inf>2</inf> (males: 3.80±0.58 vs. 3.26±0.60 L/min, P<0.001; females: 2.65±0.26 vs. 2.36±0.21, P<0.001), and average 15 min recovery VO<inf>2</inf> (males: 1.15±0.20 vs. 0.99±0.17 L/min, P<0.001; females: 0.77±0.10 vs. 0.71±0.07 L/min, P=0.019) were significantly higher in HIFT vs. TRAD. Aerobic energy expenditure was significantly higher in HIFT compared to TRAD in males (9.01±1.43 vs. 8.53±1.38 kcal/min, P=0.002) but was not significantly different between the two workouts in females (6.04±0.53 vs. 5.97±0.50 kcal/min, P=0.395). Postexercise systolic blood pressure (SBP) was significantly higher than pre-exercise SBP following both HIFT (males: 124±13 mmHg pre to 154±28 mmHg post, P<0.001; females: 110±7 mmHg pre to 140±15 mmHg post, P<0.001) and TRAD (males: 124±13 mmHg pre to 142±16 mmHg post, P=0.002; females: 112±8 mmHg pre to 123±10 mmHg post, P=0.002), however, HIFT led to a greater increase compared to TRAD in females (P=0.001). Postexercise diastolic blood pressure (DBP) was significantly lower than pre-exercise DBP following both HIFT (males: 77±9 mmHg pre to 64±6 mmHg post, P<0.001; females: 71±8 mmHg pre to 64±7 mmHg post, P=0.011) and TRAD (males: 82±7 mmHg pre to 72±7 mmHg post, P<0.001; females: 73±8 mmHg pre to 65±8 mmHg post, P<0.001). Mean arterial blood pressure was unchanged following both workouts. High-intensity functional training may be an effective form of exercise for caloric expenditure and may elicit greater cardiorespiratory stress than traditional exercise.

Effects of post-exercise sodium bicarbonate ingestion on acid-base balance recovery and time-to-exhaustion running performance: a randomised crossover trial in recreational athletes.

This study investigated the effect of post-exercise sodium bicarbonate (NaHCO3) ingestion on acid-base balance recovery and time-to-exhaustion (TTE) running performance. Eleven male runners (stature, 1.80± 0.05m; body mass, 74.4± 6.5kg; maximal oxygen consumption, 51.7± 5.4mL·kg-1·min-1) participated in this randomised, single-blind, counterbalanced and crossover design study. Maximal running velocity (v-V̇O2max) was identified from a graded exercise test. During experimental trials, participants repeated 100% v-V̇O2max TTE protocols (TTE1, TTE2) separated by 40min following the ingestion of either 0.3g·kg-1 body mass NaHCO3 (SB) or 0.03g·kg-1 body mass sodium chloride (PLA) at the start of TTE1 recovery. Acid-base balance (blood pH and bicarbonate, HCO3-) data were studied at baseline, post-TTE1, after 35min recovery and post-TTE2. Blood pH and HCO3- concentration were unchanged at 35 min recovery (p> 0.05), but HCO3- concentration was elevated post-TTE2 for SB vs. PLA (+2.6 mmol·L-1; p= 0.005; g= 0.99). No significant differences were observed for TTE2 performance (p> 0.05), although a moderate effect size was present for SB vs. PLA (+14.3s; g= 0.56). Post-exercise NaHCO3 ingestion is not an effective strategy for accelerating the restoration of acid-base balance or improving subsequent TTE performance when limited recovery is available. Novelty: Post-exercise sodium bicarbonate ingestion did not accelerate the restoration of blood pH or bicarbonate after 35min. Performance enhancing effects of sodium bicarbonate ingestion may display a high degree of inter-individual variation. Small-to-moderate changes in performance were likely due to greater up-regulation of glycolytic activation during exercise.