Submaximal, Low-Dose Eccentric vs Traditional Cycling Exercise: Reduced Oxygen Uptake and Pulmonary Artery Pressure Assessed by Echocardiography in Healthy Middle-aged Adults. A Randomized Controlled, Crossover Trial.

Objective: To investigate the ventilatory and circulatory differences between eccentric (ECC) and concentric (CON) cycling exercise at submaximal, low-dose intensity from onset to end-exercise in healthy middle-aged participants. Design: Randomized controlled crossover trial. Setting: The participants underwent 1 ECC and 1 CON test according to stepwise incremental exercise protocols at identical, submaximal intensities. Breath-by-breath analyses of ventilatory gas exchange and echocardiography were used to assess cardiopulmonary function during exercise. Participants: 24 healthy middle-aged, untrained participants (14 women, 10 men, 50±14 years) were included. Interventions: 1 ECC and 1 CON test at submaximal intensities. Main Outcome Measure: The main outcome was oxygen uptake (V'O2). Results: The V'O2 increase was reduced by -422 mL/min (-52%, 95% confidence interval: -513 to -292, P<.001) during ECC, as well as the ventilatory drive. Echocardiographic parameters, heart rate (-14%), cardiac output (-21%), stroke volume (-15%), and pulmonary artery pressure by tricuspid regurgitation pressure gradient (TRPG) (-26%) were also significantly reduced during ECC compared with CON at identical intensities. Participants reported significantly less dyspnea and unchanged perceived leg fatigue in ECC. Conclusion: ECC was well tolerated, and significant reductions were observed in V'O2, ventilation, and right ventricular load compared with CON, even at low intensity levels. This study, conducted on healthy middle-aged participants, did not raise concerns that would hinder further investigation of the effects of ECC in patients with severely limited cardiopulmonary disease, and it calls for further research on this topic.

Acute performance fatigability following continuous versus intermittent cycling protocols is not proportional to total work done.

Classical training theory postulates that performance fatigability following a training session should be proportional to the total work done (TWD); however, this notion has been questioned. This study investigated indices of performance and perceived fatigability after primary sessions of high-intensity interval training (HIIT) and constant work rate (CWR) cycling, each followed by a cycling time-to-task failure (TTF) bout. On separate days, 16 participants completed an incremental cycling test, and, in a randomized order, (i) a TTF trial at 80% of peak power output (PPO), (ii) an HIIT session, and (iii) a CWR session, both of which were immediately followed by a TTF trial at 80% PPO. Central and peripheral aspects of performance fatigability were measured using interpolated twitch technique, and perceptual measures were assessed prior to and following the HIIT and CWR trials, and again following the TTF trial. Despite TWD being less following HIIT (P = 0.029), subsequent TTF trial was an average of 125 s shorter following HIIT versus CWR (P < 0.001), and this was accompanied by greater impairments in voluntary and electrically evoked forces (P < 0.001), as well as exacerbated perceptual measures (P < 0.001); however, there were no differences in any fatigue measure following the TTF trial (P ≥ 0.149). There were strong correlations between the decline in TTF and indices of peripheral (r = 0.70) and perceived fatigability (r ≥ 0.80) measured at the end of HIIT and CWR. These results underscore the dissociation between TWD and performance fatigability and highlight the importance of peripheral components of fatigability in limiting endurance performance during high-intensity cycling exercise.

Effect of Adding Early Bedside Cycling to Inpatient Cardiac Rehabilitation on Physical Function and Length of Stay After Heart Valve Surgery: A Randomized Controlled Trial.

OBJECTIVE: To assess whether adding bedside cycling to inpatient cardiac rehabilitation (CR) early after heart valve surgery could lead to better physical function and shorter length of hospital stays. DESIGN: This is a single-centered, randomized, controlled, parallel-group intervention study. SETTINGS: This study was conducted at the National Heart Institute from December 2022 to June 2023. PARTICIPANTS: Thirty-one patients following heart valve surgery completed this study after being randomized into 2 groups: an intervention group (n1=16) and an active control group (n2=15). Eligibility criteria were heart valve surgery with median sternotomy, clinical stability, and age from 20 to 40 years. INTERVENTIONS: The intervention group received early bedside cycling for the lower limbs, using a mini bike, in addition to an inpatient CR program, and the control group received the inpatient CR program alone. MAIN OUTCOME MEASURE: The primary outcome was the physical functional capacity assessed by the 6-minute walk distance (6MWD). The secondary outcomes were the Barthel Index (BI), the forced vital capacity (FVC), the length of intensive care unit (ICU) stay, the total length of hospital stay, and the physical component summary (PCS) of the 12-item Short Form (SF-12) Health Survey. RESULTS: Compared with the control group, the intervention group showed significantly greater 6MWD (P<.001), BI score (P<.001), and FVC (P=.006) at hospital discharge, and shorter ICU stay (P=.002) and total hospital stay (P=.015). At 1-month follow-up, the intervention group showed a non-significantly higher PCS mean score than the control group (P=.057). CONCLUSION: Adding early bedside cycling to a usual inpatient CR program after heart valve surgery could induce significantly greater short-term physical functional capacity as assessed by the 6MWD, better activities of daily living as evaluated by the BI, higher pulmonary function as measured by the FVC, and shorter lengths of ICU and total hospital stays than the usual inpatient CR program alone.

Relationship between aerobic fitness and lower limb skin temperature during cycling exercise testing among well-trained athletes and nonathletes: a cross-sectional study.

Background: During prolonged physical exercise, the skin plays an important role in thermoregulation by dissipating heat to maintain core temperature. Moreover, thermal variation may be influenced by the physical fitness level of an individual. The aim of the present study was to determine the relationship between aerobic fitness and lower limb skin temperature during graded cycling exercise testing in well-trained athletes and nonathletes. Methods: Twelve trained athletes (mean ± SD maximal oxygen consumption [VO2max], 52.44 ± 4.5 ml/kg/min) and 12 nonathletes (VO2max, 36.95 ± 4.9 ml/kg/min) participated in this study. The regional skin temperature over the lower limbs was monitored continuously during incremental exercise testing using a thermal camera, and cardio-respiratory parameters were assessed and recorded using a metabolic analyzer (K5, COSMED, Rome, Italy). Results: The mean skin temperature of athletes at a high intensity of exercise was 27.23 ± 0.3 °C while that of nonathletes was 29.03 ± 0.44 °C, a difference that was statistically significant (p < 0.05). A negative correlation was observed between skin temperature and cardiovascular parameters (VO2max and heart rate) in athletes, while no such correlation was found among nonathletes. Conclusion: The present study demonstrated a negative correlation between oxygen consumption and lower limb skin temperature in athletes, while the correlation was poor in nonathletes. This suggests that physical fitness level may influence the pattern of alterations in lower limb skin temperature, which supports the hypothesis that athletes exhibit better heat dissipation mechanisms than nonathletes.

Relationship Between Muscle Deoxygenation and Cardiac Output in Subjects Without Attenuation of Deoxygenation Hemoglobin Concentration Near the End of Ramp Cycling Exercise: A Longitudinal Study.

The aim of this study was to investigate the longitudinal relationship between the slopes of systemic and quadriceps muscle O2 dynamics in subjects without attenuation point in deoxygenated hemoglobin concentration at vastus lateralis (APdeoxy-Hb@VL) during high-intensity cycling. Seven young men without APdeoxy-Hb@VL performed ramp cycling exercise until exhaustion before and after 8 weeks, while continuing recreational physical activities throughout that period. Muscle O2 saturation (SmO2) and deoxy-Hb were monitored at the vastus lateralis (VL) and rectus femoris (RF) by near infrared spectroscopy oximetry during exercise. Cardiac output (CO) was also continuously assessed. During high-intensity exercise, at VL, a significantly steeper slope of deoxy-Hb was found after 8 weeks compared with before, while the slopes of deoxy-Hb at RF were not significantly changed. Though a decrease in the slope of CO after 8 weeks did not reach significance (p = 0.12), the change in the slope of CO was significantly related to the change in the slopes of deoxy-Hb at VL (rs = -0.89, p < 0.01) and RF (rs = -0.86, p < 0.05). Our data reinforces the idea that, in subjects without APdeoxy-Hb@VL, the slope of muscle deoxygenation at VL during high-intensity cycling exercise may partly be explained by systemic O2 supply, rather than O2 balance in other thigh muscles.

Prefrontal oxygenation is quantified with time-resolved near-infrared spectroscopy: effect of sex on baseline oxygenation and the response during exercise.

With the use of time-resolved near-infrared spectroscopy that enables quantitative analysis of optical properties and oxygenation in cerebral tissues and thereby subject-to-subject comparisons in the variables, this study examined the influence of sex on baseline optical properties and oxygenation in the prefrontal cortex (PFC) and the responses during cycling exercise. Absolute levels of oxygenated- and deoxygenated-hemoglobin concentration (Oxy-Hb and Deoxy-Hb) in bilateral PFC were measured at rest and during unilateral cycling at low and moderate intensity in young participants (8 women and 10 men). Unilateral cycling was utilized to evaluate no lateralization of the prefrontal oxygenation responses during exercise. Baseline optical properties of bilateral PFC, defined optical path length and reduced scattering coefficient, and their responses during cycling were not different between the sexes. Baseline absolute Oxy-Hb of bilateral PFC was significantly lower in women (37 ± 3 µM) than in men (47 ± 7 µM), whereas absolute Deoxy-Hb revealed no sex-related difference. The absolute Oxy-Hb levels in bilateral PFC during low- and moderate-intensity cycling were also lower in women. However, no sex difference was observed when using changes against the baseline levels to normalize baseline differences. No laterality-related differences were observed in the changes in prefrontal Oxy-Hb and Deoxy-Hb during unilateral cycling. Ascertaining no sex-related difference in optical properties of the PFC, the current findings suggest that baseline absolute level of oxygenation in the PFC is lower in women than in men, likely due to lower oxygen supply rather than higher oxygen utilization, and that prefrontal oxygenation responds similarly during exercise independently of sex.

Development and Evaluation of Wireless Interfaces to Monitor and Control Cycling Exercise During Home Telerehabilitation.

Purpose: This paper focuses on developing and testing three versions of interactive bike (iBikE) interfaces for remote monitoring and control of cycling exercise sessions to promote upper and lower limb rehabilitation. Methods: Two versions of the system, which consisted of a portable bike and a tablet PC, were designed to communicate through either Bluetooth low energy (BLE) or Wi-Fi interfaces for real-time monitoring of exercise progress by both the users and their clinical team. The third version of the iBikE system consisted of a motorized bike and a tablet PC. It utilized conventional Bluetooth to implement remote control of the motorized bike's speed during an exercise session as well as to provide real-time visualization of the exercise progress. We developed three customized tablet PC apps with similar user interfaces but different communication protocols for all the platforms to provide a graphical representation of exercise progress. The same microcontroller unit (MCU), ESP-32, was used in all the systems. Results: Each system was tested in 1-minute exercise sessions at various speeds. To evaluate the accuracy of the measured data, in addition to reading speed values from the iBikE app, the cycling speed of the bikes was measured continuously using a tachometer. The mean differences of averaged RPMs for both data sets were calculated. The calculated values were 0.38 ± 0.03, 0.25 ± 0.27, and 6.7 ± 3.3 for the BLE system, the Wi-Fi system, and the conventional Bluetooth system, respectively. Conclusion: All interfaces provided sufficient accuracy for use in telerehabilitation.

Comparative Analysis of Heart Rate Variability Parameters between Surya Namaskar and Stationary Bike Exercise Groups.

Background: Yoga practice has multiple health benefits. Surya Namaskar (SN) also known as sun salutation presents mental and physical health benefits equivalent to physical exercise. It consists of a sequence of 12 Hatha yoga postures with coordinated breathing. Aims: This study evaluated the effect of SN against mild intensity stationary cycling exercise (SCE) on parameters of heart rate variability (HRV). Methodology: This study was conducted in the department of physiology of a nationally important institute after obtaining ethics approval. A total of 40 healthy participants (males aged 46 ± 2.3 years) were enrolled in the study and divided into two groups, namely SN group and exercise group (SG and EG). The allocation on the group was based on subjects' choice and interest in performing SN or SCE. Baseline HRV, anthropometric measurement, and blood pressure were assessed. SG was subjected to 14 rounds of SN in about 20 min and EG to a 20-min mild-intensity stationary cycling session (30%-50% maximal heart rate). Assessments were conducted preexercise and postexercise recovery. HRV was assessed with the NeuralChek device. Results: SN led to increased SDNN, pNN50, RMSSD, and total power, indicating improved autonomic balance, cardiovascular health, and parasympathetic dominance. Conversely, SCE decreased SDNN, pNN50, and RMSSD, suggesting immediate postexercise sympathetic dominance. Spectral analysis of HRV highlighted autonomic balance differences, with SN increasing low frequency (LF%) reflecting both sympathetic and parasympathetic dominance, whereas exercise reduced LF% due to sympathetic activation. Minimal changes were observed in high-frequency percentage. SN combines flexibility, strength, and balance, providing a balanced physical activity. This balance results in a mixed autonomic response, with sympathetic activity for the physical effort and parasympathetic activity for the relaxation components. Conclusions: SN positively impacted HRV, promoting parasympathetic dominance and cardiovascular health, whereas exercise induced sympathetic activation with potential recovery benefits. Monitoring HRV offers insights into cardiovascular fitness and well-being. The study underscores the merits of incorporating yoga such as SN into daily activity routines.

Surface electromyographic activity of the erector spinae and multifidus during arm- and leg-ergometer exercises in young healthy men.

Objectives: Ergometer exercise was considered a new loading method that can be used for participants who are unable to assume the core strengthening exercise posture commonly used to strengthen the erector spinae and multifidus. This study aimed to investigate with healthy participants whether arm and leg ergometers could be used for core strengthening exercises and whether different exercise sites would affect the results. Methods: The study was conducted with 15 healthy adult male participants aged 20-35 years. The intervention consisted of arm- and leg-ergometer exercises performed by the participants. The exercise protocol consisted of three 1-min sessions (rest, 50W, and 100 W), which were measured consecutively. Surface electromyography (sEMG) was measured during the sessions. Maximal voluntary contraction (MVC) of the erector spinae and multifidus was also measured, during which sEMG was measured. The sEMG during ergometer exercise was calculated as a percentage of the MVC (calculated as % MVC). The root mean square (RMS) was recorded from the sEMG activity. Muscle activity of the erector spinae and multifidus was compared between ergometer exercises and between intensity levels. Heart rate (HR) was recorded by electrocardiogram. Results: In the arm-ergometer exercise, the % MVC values of the erector spinae were 6.3 ± 3.1, 10.9 ± 5.4, and 16.9 ± 8.3% at rest, 50 W, and 100 W conditions, respectively. The multifidus was 4.6 ± 2.9, 9.2 ± 5.6, and 12.6 ± 7.6% at rest, 50 W, and 100 W conditions, respectively. The respective % MVC values during the leg-ergometer exercise were 3.8 ± 1.7, 7.2 ± 3.8, and 10.4 ± 4.0% at rest, 50 W, and 100 W conditions, respectively. Leg-ergometer exercises were 2.6 ± 2.1, 6.9 ± 5.7, and 10.3 ± 6.8% at rest, 50 W, and 100 W conditions, respectively. The activities of the two muscles increased at comparable levels with increased workload in both types of exercises (p < 0.01, each). HR increased with the increased workload and the increase was larger during arm-than leg-ergometer exercises. Conclusion: These results demonstrate that both arm- and leg-ergometer exercises are potentially alternative methods for erector spinae and multifidus training for healthy participants. Further research is needed to target elderly.

Adding Vibration During Varied-Intensity Work Intervals Increases Time Spent Near Maximal Oxygen Uptake in Well-Trained Cyclists.

PURPOSE: Previous research suggests that the percentage of maximal oxygen uptake attained and the time it is sustained close to maximal oxygen uptake (eg, >90%) can serve as a good criterion to judge the effectiveness of a training stimulus. The aim of this study was to investigate the acute effects of adding vibration during varied high-intensity interval training (HIIT) sessions on physiological and neuromuscular responses. METHODS: Twelve well-trained cyclists completed a counterbalanced crossover protocol, wherein 2 identical varied HIIT cycling sessions were performed with and without intermittent vibration to the lower-intensity workloads of the work intervals (6 × 5-min work intervals and 2.5-min active recovery). Each 5-minute work interval consisted of 3 blocks of 40 seconds performed at 100% of maximal aerobic power interspersed with 60-second workload performed at a lower power output, equal to the lactate threshold plus 20% of the difference between lactate threshold and maximal aerobic power. Oxygen uptake and electromyographic activity of lower and upper limbs were recorded during all 5-minute work intervals. RESULTS: Adding vibration induced a longer time ≥90% maximal oxygen uptake (11.14 [7.63] vs 8.82 [6.90] min, d = 0.64, P = .048) and an increase in electromyographic activity of lower and upper limbs during the lower-intensity workloads by 20% (16%) and 34% (43%) (d = 1.09 and 0.83; P = .03 and .015), respectively. CONCLUSION: Adding vibration during a varied HIIT session increases the physiological demand of the cardiovascular and neuromuscular systems, indicating that this approach can be used to optimize the training stimulus of well-trained cyclists.

ECG Approximate Entropy in the Elderly during Cycling Exercise.

Approximate entropy (ApEn) is used as a nonlinear measure of heart-rate variability (HRV) in the analysis of ECG time-series recordings. Previous studies have reported that HRV can differentiate between frail and pre-frail people. In this study, EEGs and ECGs were recorded from 38 elderly adults while performing a three-stage cycling routine. Before and after cycling stages, 5-min resting-state EEGs (rs-EEGs) and ECGs were also recorded under the eyes-open condition. Applying the K-mean classifier to pre-exercise rs-ECG ApEn values and body weights revealed nine females with EEG power which was far higher than that of the other subjects in all cycling stages. The breathing of those females was more rapid than that of other subjects and their average heart rate was faster. Those females also presented higher degrees of asymmetry in the alpha and theta bands (stronger power levels in the right frontal electrode), indicating stressful responses during the experiment. It appears that EEG delta activity could be used in conjunction with a very low ECG frequency power as a predictor of bursts in the heart rate to facilitate the monitoring of elderly adults at risk of heart failure. A resting ECG ApEn index in conjunction with the subject's weight or BMI is recommended for screening high-risk candidates prior to exercise interventions.

Neuromuscular Fatigue Responses of Endurance- and Strength-Trained Athletes during Incremental Cycling Exercise.

This study explored the development of neuromuscular fatigue responses during progressive cycling exercise. The sample comprised 32 participants aged 22.0 ± 0.54 years who were assigned into three groups: endurance-trained group (END, triathletes, n = 10), strength-trained group (STR, bodybuilders, n = 10) and control group (CG, recreationally active students, n = 12). The incremental cycling exercise was performed using a progressive protocol starting with a 3 min resting measurement and then 50 W workload with subsequent constant increments of 50 W every 3 min until 200 W. Surface electromyography (SEMG) of rectus femoris muscles was recorded during the final 30 s of each of the four workloads. During the final 15 s of each workload, participants rated their overall perception of effort using the 20-point rating of the perceived exertion (RPE) scale. Post hoc Tukey's HSD testing showed significant differences between the END and STR groups in median frequency and mean power frequency across all workloads (p < 0.001 and p < 0.01, respectively). Athletes from the END group had significantly lower electromyogram amplitude responses than those from the STR (p = 0.0093) and CG groups (p = 0.0006). Increasing RPE points from 50 to 200 W were significantly higher in the STR than in the END group (p < 0.001). In conclusion, there is a significant variation in the neuromuscular fatigue profiles between athletes with different training backgrounds when a cycling exercise is applied. The approximately linear trends of the SEMG and RPE values of both groups of athletes with increasing workload support the increased skeletal muscle recruitment with perceived exertion or fatiguing effect.

Venous volume and compliance in the calf and forearm does not change after acute endurance exercise performed at continuous or interval workloads.

Short-term endurance exercise training for 6-8 weeks leads to increases in venous volume and compliance in the limbs. However, it is not known whether these venous vascular properties are improved by acute endurance exercise. We examined the effects of acute endurance exercise involving continuous or interval workloads on venous volume and compliance in the exercising (calf) and non-exercising (forearm) limbs. Sixteen healthy young volunteers performed cycling exercise involving a continuous workload of 60% heart rate (HR) reserve or an interval workload of 40% HRreserve and 80% HRreserve, alternating every 2 min, for a total of 32 min each. Before and 60 min after acute cycling exercise, venous volume in the calf and forearm was measured by venous occlusion plethysmography during a cuff-deflation protocol with a venous collecting cuff wrapped to the thigh and upper arm and strain gauges attached to the calf and forearm. The cuff pressure was maintained at 60 mmHg for 8 min and was then deflated to 0 mmHg at a rate of 1 mmHg/s. Venous compliance was calculated as the numerical derivative of the cuff pressure-limb venous volume curve. In both the calf and forearm, the cuff pressure-venous volume curve and the cuff pressure-venous compliance relationship did not differ between before and 60 min after exercise involving continuous or interval workloads. These results suggest that acute exercise does not improve venous volume and compliance in both the exercising and non-exercising limbs.

Transient speeding of V̇O2 kinetics following acute sessions of sprint interval training: Similar exercise dose but different outcomes in older and young adults.

An acute session of sprint interval training (SIT) is a potent stimulus for the metabolic and cardiovascular systems. However, the feasibility of SIT in older adults and its effectiveness to acutely improve aerobic function by transiently accelerating the rate of adjustment of oxidative phosphorylation quantified by V̇O2 kinetics (τV̇O2) are unknown. This study evaluated the time course of changes of τV̇O2 in response to different doses of SIT in older inactive adults compared to their young counterparts. Eight older (age: 67 ± 3 years) and eight young (age: 30 ± 3 years) adults completed three separate SIT sessions consisting of either one (SIT1), three (SIT3), or five (SIT5) consecutive bouts of SIT. Each SIT intervention was interspersed by a two-week recovery phase. The bike resistance during the sprints was set at 0.065 kg·kg-1 body mass for older and 0.075 kg·kg-1 body mass for young adults. Moderate-intensity step-transitions were performed to assess τV̇O2 before (PRE) and one (1d), two (2d) and three (3d) days post each SIT intervention. Older adults attained lower peak power outputs, average power output, and blood lactate concentrations across all sprints of each SIT intervention compared to young (P < 0.01). Following SIT1, τV̇O2 was faster at 1d (-13.6%; P = 0.008) and 2d (-12.7%; P = 0.017) and returned to values similar to PRE at 3d (+0.4%; P > 0.05) in both older and young. Following SIT3, τV̇O2 was faster at 1d (-20.6%; P < 0.001), 2d (-18.5%; P = 0.011), and 3d (-14.5%; P = 0.045) compared to PRE in both older and young. Following SIT5, τV̇O2 became faster in older (at 1d, 2d, and 3d; ~25%; P < 0.05) but remained unchanged in young with respect to PRE (P > 0.05). These findings indicate that SIT has the potency to acutely improve aerobic function by speeding the rate of adjustment of oxidative phosphorylation. However, only older adults were able to maintain these beneficial effects when the volume of SIT was maximized (SIT5). Future studies are warranted to evaluate the long-term feasibility of SIT in older adults.

Effects of Lower Limb Cycling Training on Different Components of Force and Fatigue in Individuals With Parkinson's Disease.

The strength of lower extremity is important for individuals to maintain balance and ambulation functions. The previous studies showed that individuals with Parkinson's disease suffered from fatigue and strength loss of central origin. The purpose of this study was to investigate the effect of lower extremities' cycling training on different components of force and fatigue in individuals with Parkinson's disease. Twenty-four individuals (13 males, 11 females, mean age: 60.58 ± 8.21 years) diagnosed with idiopathic Parkinson's disease were randomized into training and control groups. The maximum voluntary contraction (MVC) force, voluntary activation level (VA), and twitch force of knee extensors were measured using a custom-made system with surface electrical stimulation. The general, central, and peripheral fatigue indexes (GFI, CFI, and PFI) were calculated after a fatiguing cycling protocol. Subjects received 8 weeks of low resistance cycling training (training group) or self-stretching (control group) programs. Results showed that MVC, VA, and twitch force improved (p < 0.05) only in the training group. Compared to the baseline, central fatigue significantly improved in the training group, whereas peripheral fatigue showed no significant difference in two groups. The cycling training was beneficial for individuals with Parkinson's disease not only in muscle strengthening but also in central fatigue alleviation. Further in-depth investigation is required to confirm the effect of training and its mechanism on central fatigue.

Optimization of pulmonary function, functional capacity, and quality of life in adolescents with thoracic burns after a 2-month arm cycling exercise programme: A randomized controlled study.

BACKGROUND: Burns to the thorax are at high risk for long-term pulmonary complications due to chest muscle contractures and chronic inflammation in both adolescents and young adults. Few studies have investigated the effects of arm cycling exercise in those individuals. For that reason, this study examined pulmonary function, functional capacity, and quality of life (QOL) in adolescents with thoracic burns subsequent to 2-month arm cycling exercise programme. METHODS: A single-blinded, two-month randomized prospective controlled study was carried out between July 2019 and March 2020 on thirty adolescents with chest burns aged 11-17 years. They were randomized into two equal groups (n = 15), traditional physiotherapy programme (control group), and arm cycling exercise plus traditonal physiotherapy (arm cycling exercise group) for 2 consecutive months. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), six-minute walk test (6MWT), and Pediatric Quality of Life Inventory (PedsQL) were measured in both groups at baseline and after 2-month after intervention. RESULTS: No statistical significance was detected at baseline between control and arm cycling exercise groups (FVC, p = 0.903, FEV1, p = 0.835, 6MWT, p = 0.817, and PedsQL, p = 0.612). 2 months after intervention showed statistical improvements in the arm cycling exercise group in all measures (FVC, p = 0.001, FEV1, p < 0.0001, 6MWT, p = 0.001, and PedsQL, p = 0.001) however, the control group showed statistical improvements in FVC, p = 0.044 and FEV1, p = 0.024 with non-statistically significant changes in 6MWT, p = 0.145 and PedsQL, p = 0.067. The arm cycling exercise group showed greater improvements than control group in the outcome measures (FVC, p = 0.034, FEV1, p < 0.017, 6MWT, p = 0.037, and PedsQL, p = 0.021). CONCLUSIONS: This prospective study clearly demonstrated positive and beneficial influences of two-month arm cycling exercise in the optimization of pulmonary functions, functional performance, and QOL in adolescents suffering from chest burns and thereby eliminating post-burn complications.

Physiological responses, self-reported health effects, and cognitive performance during exposure to carbon dioxide at 20 000 ppm.

In this study, 24 subjects (20-58 years) were exposed to carbon dioxide (CO2 ) at 770 ppm and 20 000 ppm in an exposure laboratory for 4-h, including 2 × 15 min of cycling to investigate the effects on acid-base balance, physiological responses, cognitive performance and acute health. Capillary blood analysis, heart rate, respiratory rate, divided attention, flexibility, and sustained attention from the Test Battery for Attentional Performance (TAP), critical flicker fusion frequency (CFF), and self-reported symptoms were measured before, during, and after the 4-h exposure. Blood pH decreased and partial pressure of carbon dioxide (pCO2 ) increased significantly when exposed to 20 000 ppm CO2 compared to 770 ppm. However, the values remained within the normal range. In addition, respiratory rate increased slightly but significantly at 20 000 ppm CO2 . No significant changes in heart rate, CFF, task performance or acute health were found. In sum, the findings suggest that the observed changes in acid-base balance and ventilation can be classified as physiological adaptation responses. Impairment of cognitive performance is not expected from exposure to 20 000 ppm CO2 , neither as direct effect on central nervous system function nor as a distraction related to perception of health effects.

Heart rate variability kinetics during different intensity domains of cycling exercise in healthy subjects.

The purpose of this study was to verify the heart rate variability (HRV) and heart rate (HR) kinetics during the fundamental phase in different intensity domains of cycling exercise. Fourteen males performed five exercise sessions: (1) maximal incremental cycling test; (2) two rest-to-exercise transitions for each intensity domain, that is, heavy (Δ30) and severe (Δ60) domains. HRV markers (SD1 and SD2) and HR kinetics in the fundamental phase were analyzed by first-order exponential fitting. There were no significant differences in amplitude values between SD1Δ30 (8.98 ± 3.52 ms) and SD1Δ60 (9.44 ± 3.24 ms) and SD2Δ30 (24.93 ± 9.16 ms) and SD2Δ60 (25.98 ± 7.29 ms). Significant difference was observed between HRΔ30 (52 ± 7 bpm) and HRΔ60 (63 ± 8 bpm). The time constant (τ) values were significantly different between SD1Δ30 (17.61 ± 6.26 s) and SD1Δ60 (13.86 ± 5.90 s), but not between SD2Δ30 (20.06 ± 3.73 s) and SD2Δ60 (19.47 ± 6.03 s) or HRΔ30 (56.75 ± 18.22 s) and HRΔ60 (58.49 ± 15.61 s). However, the τ values for HRΔ30 were higher and significantly different in relation to SD1Δ30 and SD2Δ30, as well as for HRΔ60 in relation to SD1Δ60 and SD2Δ60. The kinetics of the autonomic variable (SD1 marker) was accelerated by the increased intensity. Moreover, significant differences were found for the τ values, with faster HRV markers than HR, in both intensities of Δ30 and Δ60, which suggests that these variables indicate distinct and specific cardiac autonomic response times during different intensity domains in cycling.HIGHLIGHTSThe application of HRV to optimize exercise prescription at different effort intensities is extremely important to obtain assertive and effective results.Analysis of the kinetic responses of HRV is a useful tool for the evaluation of exercise performance and health status.A faster kinetics was found for HRV markers in comparison to HR, for both intensities analysed, which suggests that these variables indicate distinct and specific cardiac autonomic response times during different intensity domains in cycling.

Effects of Blood Flow Restriction on O2 Muscle Extraction and O2 Pulmonary Uptake Kinetics During Heavy Exercise.

This study aimed to determine the effects of three levels of blood flow restriction (BFR) on V ˙ O 2 and O 2 extraction kinetics during heavy cycling exercise transitions. Twelve healthy trained males completed two bouts of 10 min heavy intensity exercise without BFR (CON), with 40% or 50% BFR (BFR40 and BFR50, respectively). V ˙ O 2 and tissue saturation index (TSI) were continuously measured and modelled using multiexponential functions. The time constant of the V ˙ O 2 primary phase was significantly slowed in BFR40 (26.4 ± 2.0s; p < 0.001) and BFR50 (27.1 ± 2.1s; p = 0.001) compared to CON (19.0 ± 1.1s). The amplitude of the V ˙ O 2 slow component was significantly increased (p < 0.001) with BFR in a pressure-dependent manner 3.6 ± 0.7, 6.7 ± 0.9 and 9.7 ± 1.0 ml·min-1·kg-1 for CON, BFR40, and BFR50, respectively. While no acceleration of the primary component of the TSI kinetics was observed, there was an increase (p < 0.001) of the phase 3 amplitude with BFR (CON -0.8 ± 0.3% VS BFR40 -2.9 ± 0.9%, CON VS BFR50 -2.8 ± 0.8%). It may be speculated that BFR applied during cycling exercise in the heavy intensity domain shifted the working muscles to an O 2 dependent situation. The acceleration of the extraction kinetics could have reached a plateau, hence not permitting compensation for the slowdown of the blood flow kinetics, and slowing V ˙ O 2 kinetics.

Does Attentional Focus Influence Psychophysiological Responses to an Acute Bout of Exercise? Evidence From an Experimental Study Using a Repeated-Measures Design.

Attentional focus during aerobic exercise has been studied in the context of sports performance, injury prevention and affective experience. Previous research suggests that an additional mental task parallel to the physical activity might influence exercise experience and performance. It has been tested if attentional focus influences cardiovascular activity, positive/negative affect, and subjective exertion during a cycling exercise. Data from N = 30 female participants has been collected using a repeated measures design, with the following experimental manipulations: (A) an internal attention focus (i.e., paying attention to force production of the quadriceps muscles), (B) an external attention focus (i.e., paying attention to changes in brightness in the cycling track simulation), and as control conditions, (C) exercise without attention focus (i.e., no specific instruction was given) and (D) no exercise, no attention focus. Subjective affect and subjective exertion were assessed, and changes in cardiovascular activity were recorded via mobile impedance cardiography (ICG) at rest, during and after the exercise, including HR, HRV (RMSSD, HF), PEP, CO, SV, LVET, and RSA. Exercise was associated with adaptations in cardiovascular activity, positive/negative affect, and subjective exertion. However, this did not interact with attentional focus. The original hypothesis could not be supported: instructed attentional focus does not influence affect, exertion, or cardiovascular activity during a cycling exercise. Therefore, attentional focusing during exercise does not appear to put notable additional mental demands on the physically active participant. Nonetheless, impedance cardiography delivered reliable measurements even during the cycling exercise.