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BACKGROUND: Bilateral strength asymmetry and fatigue predispose athletes to various injuries and conventional methods appear to be poor predictors of lower extremity muscular performance under NF conditions. OBJECTIVE: The purpose of the study was to compare the conventional Hcon/Qcon (HQR) ratio and the dynamic control ratio (DCR: Hecc/Qcon) under non-fatiguing (NF) and fatiguing (F) conditions and verify the effects of heavy-intensity constant running and cycling exercise on the isokinetic performance. METHODS: Twenty healthy male participants performed running and cycling VO2max at work-rate associated with the achievement of VO2max (TTE). Isokinetic muscle strength performance was tested at 60 and 180∘/s before and after these sessions with 48-hour intervals. Quadriceps (QFR) and hamstring (HFR) muscle fatigue rates were also calculated during these sessions. Blood lactate concentration was measured before and two-minutes after running and cycling TTE. RESULTS: No between-condition differences were found for the HQR while the DCR decreased significantly at 180∘/s following cycling and running sessions (p< 0.05). Cycling TTE was positively correlated with in dominant (r= 0.535, p= 0.015) and non-dominant (r= 0.446, p= 0.048) QFR. Positive correlations were also found between running TTE and dominant (r= 0.500, p= 0.25) and non-dominant (r= 0.465, p= 0.039) HFR. CONCLUSIONS: The DCR obtained at fast angular velocities following a strenuous exercise seems to be the best indicator of muscle performance while its assessment under F conditions reveals higher ratios compared to NF conditions and conventional methods.

The aim of this study was to compare the exercise demands between two intermittent small-sided games (SSGs) and their temporal changes throughout SSGs repetitions, while controlling for total exercise duration. Exercise demands were recorded using wearable 10-Hz global positioning system technology with a 100-Hz accelerometer embedded and heart rate (HR) monitors in eight U17 male professional football players (age = 16.3 ± 0.5 years old) during two 18-min 4v4 plus goalkeepers SSGs based on long bouts (LB; 3 × 6 min) and short bouts (SB; 6 × 3 min) separated for 2-min rest. Total duration was 18 min, pitch dimensions were (length × width) 24 × 17 m and relative space per players was 51 m2. During LB, higher total distance, accelerations > 2 m s−2, decelerations 1.2 m s−2) and Dec2 decreased from the 1st toward 3rd bout (ES = 0.6–1.5). During SB, HRpeak and HRmean increased in the 2nd and 3rd (ES = 1.7–3.2) and then decreased in the 4th, 5th and 6th bout (ES = 0.7–3.5). The LB-based SSGs seem to produce greater physical and physiological demands than SB. However, SB induced greater fluctuations in HR while ensuring work rate maintenance across bouts.

The current study aimed to compare time spent above 90% V̇O2max (tV̇O2max) during 3 work-matched interval training protocols comprising 8×60-second exercise efforts with decreasing, increasing, or constant work rate distribution within each exercise interval. Ten healthy male subjects (age: 27.6±5.0 years; V̇O2max: 3.82±0.52 L•min–1) performed an incremental test to determine V̇O2max and peak power output (P max). During visits 2, 3, and 4, three work-matched interval training sessions comprising 8×60 s efforts: 60 s active recovery with the power output held constant (100%Pmax; ITCON), decreasing (from 110 to 90%Pmax; ITDEC), or increasing (from 90 to 110%Pmax; ITINC) linearly throughout each work interval. Time sustained above 90% of V̇O2max (tV̇O2max) or HRmax (tHRmax), blood lactate concentrations (BLC) and rating of perceived exertion (RPE) were measured. The tV̇O2max (ITCON: 274±132; ITDEC: 313±102; ITINC: 310±113 s, P=0.37), tHRmax (ITCON: 396±180; ITDEC: 441±207; ITINC: 390±212 s, P=0.47), BLC (P=0.73), and final RPE (P=0.75) were similar among protocols. In conclusion, work-matched interval training induced similar time near V̇O2max and associated physiological responses regardless of work rate manipulation.

[EN] Background: Frequently used reference values for clinical exercise testing have been derived from non-random samples and some with poorly defined maximal criteria. Our objective was to obtain population based reference values for peak oxygen uptake ( ̇VO2 ) and work rate (WR) for cardiopulmonary exercise testing in a representative sample of Caucasian Spanish men and women. Methods: 182 men and women, 20–85 years old, were included and exercised on cycle-ergometer to exhaustion. ( ̇VO2 ) and WR were measured. The equations obtained from this sample were validated in an independent cohort of 69 individuals, randomly sampled form the same population. Then a final equation merging the two cohorts (=251) was produced. Results: Height, sex and age resulted predictive of both ̇VO2 peak and WR. Weight and physical activity added very little to the accuracy to the equations. The formulas ̇VO2 peak = 0.017 · height (cm) − 0.023 · age (years) + 0.864 · sex (female = 0/male = 1) ± 179 l min−1 , and peak WR = 1.345 · height (cm) − 2.074 · age (years) + 76.54 · sex (female = 0/male = 1) ± 21.2 W were the best compromise between accuracy and parsimony. Conclusions: This study provides new and accurate ̇VO2 peak and WR rate reference values for individuals of European Spanish descent, [ES] Antecedentes: Los valores de referencia utilizados con frecuencia para las pruebas de esfuerzo clínicas derivan de muestras no aleatorias y los criterios máximos para algunos de ellos están mal definidos. Nuestro objetivo fue obtener valores de referencia basados en la población general para el consumo máximo de oxígeno (VO 2 ) y la carga de trabajo (CT) para las pruebas de ejercicio cardiopulmonar a partir de una muestra representativa de varones y mujeres caucásicos españoles. Métodos: Se incluyeron 182 varones y mujeres, de entre 20 y 85 a ̃nos, que realizaron ejercicio en el cicloergómetro hasta el agotamiento. Se midieron el VO 2 y la CT. Las ecuaciones obtenidas de esta muestra se validaron en una cohorte independiente de 69 individuos, seleccionados aleatoriamente de la misma población. A continuación, se creó una ecuación final que fusionó las dos cohortes (n = 251). Resultados: La altura, el sexo y la edad resultaron predictivos tanto del ̇VO2 máximo como de la CT. El peso y la actividad física contribuyeron muy poco a la precisión de las ecuaciones. Las fórmulas ̇VO2 máximo = 0,017 × altura (cm) − 0,023 × edad (a ̃nos) + 0,864 × sexo (mujer = 0/varón = 1) ± 179 L × min−1 ; y CT máxima = 1,345 × altura (cm) − 2,074 × edad (a ̃nos) + 76,54 × sexo (mujer = 0/varón = 1) ± 21,2 W fueron el mejor equilibrio entre precisión y parsimonia. Conclusiones: Este estudio proporciona valores de referencia del ̇VO 2 máximo y la CT nuevos y precisos para personas de ascendencia espa ̃nola europea., This study was supported by a SEPAR (Sociedad Española de Neumología y Cirugía Torácica/Spanish society of Pulmonology and Thoracic Surgery) grant and NEUMOMADRD (Sociedad Madrileña de Neumología y Cirugía Torácica/Madrilenian Society of Pulmonology and Thoracic Surgery) research award.

Small industry has a big role in encouraging development in areas, especially rural areas, which cannot be separated from national development in accordance with regional autonomy and regional aspirations. One of the small industries to fulfill development is the brick-making industry manually because it still uses a simple process in its production. Manual brick making cannot be separated from the risks that will arise for workers, one of the risks is fatigue due to the workload carried out in the process of making bricks repeatedly, the workload can be in the form of physical loads or mental loads. Fatigue from work will reduce performance and increase the rate of work errors. Increasing work errors will provide opportunities for work accidents. From this it is necessary to measure workload on work fatigue from the results of the ergonomic analysis of brickwork manual workers with Linear Regression with web-based programming. Each worker will be recorded based on the category Initial Pulse, Work Rate, Body Weight, Blood Pressure, Height, Age, as well as several questions to workers needed to measure the workload against work fatigue. Questions about Activity Weakness and Physical Fatigue in a span of days (Very Often, Often, Sometimes, Never; to each worker. The conclusion from the results of the workload analysis has an influence on fatigue of work in making bricks manually, namely Normal or Not Fatigue 6 workers , and Needs Improvement 9 workers with the percentage classification of Cardiovascular Load (CVL) is 40% and 60%.

Sitko, S, Cirer-Sastre, R, Corbi, F, and Lopez-Laval, I. Functional threshold power as an alternative to lactate thresholds in road cycling. J Strength Cond Res XX(X): 000-000, 2021-This study assessed the relationship between functional threshold power (FTP) and 7 lactate landmarks (Dmax, modified Dmax, fixed blood lactate concentrations of 2 and 4 mmol·L-1, lactate increases of 1 and 2 mmol·L-1 above baseline, and lactate increases of 1.5 mmol·L-1 above the point of minimum ratio between lactate and work rate) in a sample of 46 road cyclists with a wide range of fitness levels (age 38 ± 9 years, height 177 ± 9 cm, body mass 71.4 ± 8.6 kg, body mass index 22.7 ± 2.2 kg·m-1, fat mass 7.8 ± 4%, and V[Combining Dot Above]O2max = 61.1 ± 9.1 ml·min-1·kg-1). The cyclists performed a graded exercise test in which power outputs (POs) at the lactate landmarks were identified. Functional threshold power was established as 95% of the PO during a 20-minute test. Significance was set as p < 0.05. Statistical analyses revealed large to very large correlations between PO, relative PO (RPO), and cadence at FTP and lactate thresholds (LTs) established through Dmax, modified Dmax, and fixed lactate concentrations of 4 mmol·L-1 (r = 0.68-0.93). Significant differences (p < 0.001) were also observed for PO and RPO at FTP, fixed blood lactate concentrations of 2 mmol·L-1, and lactate increases of 1 mmol·L-1 above baseline. Therefore, although FTP estimated from a 20-minute test is strongly related to several lactate landmarks, caution is required when substituting this concept for LTs. This information will allow coaches, cyclists, and scientists to better choose assessments when attempting to estimate LT through power-based field testing.

Lampit is one of the traditional means of cultivating rice fields, which functions to level the land for planting rice. The operation of lampit can increase the work pulse up to 50% above the resting pulse and is included in the category of moderate to heavy workloads. At the end of the operation of lampit, it may cause complaints, especially on the buttocks and back, which is caused by the small and hardness of the lampit rod. There was an improvement to the lampit seating design by adding foam pads and adjusting the pressure lever found on the lampit stem to overcome this problem. This research is an experimental study using the same subject design, selected 30 research subjects from farmers in Dusun Semaja Antosari Tabanan Bali. The workload is evaluated based on the work pulse measured using the ten pulses method. In addition, the pulse was measured before and after the improvement of the lampit design. The data compared were the mean values before and after improvement, which were analyzed using paired t test (α = 0.05). The result is a significant decrease in the work rate of 19.35% (p

Background Reference values of cardiopulmonary exercise testing (CPX) vary with race/ethnicity. Chinese Americans are the fastest-growing racial/ethnic group in the United States. However, there is limited information about the reference values of cardiopulmonary exercise testing (CPX) variables in the Chinese population. Methods As part of the Xiangya Hospital Exercise Testing project (the X-ET project), this cross-sectional study screened 20,696 consecutive CPXs performed by 17,802 unique individuals at Xiangya Hospital of Central South University, China, from January 1, 2002, to December 31, 2019. A total of 964 unique healthy adults/tests (42% female) aged 49 ± 12 who completed a maximal ramp incremental CPX with cycle ergometry were included in this study. The reference values of primary CPX variables were expressed as the lower limit or upper limit of normal. Stepwise linear regression was used to fit the equations of key CPX variables. Predictive accuracy analysis for the equations with a comparison between present and previous studies were performed. Results Peak oxygen consumption ( V O2), carbon dioxide production, ventilation/min, work rate, and V O2 at the anaerobic threshold were regressed on age, height, weight, and sex. These predictive equations showed good in- and out-sample predictive accuracy. Comparison with prior research revealed that prediction equations of peak V O2 resultant from studies in which populations were entirely or primarily Caucasian had overestimated our subjects' actual values. Conclusion The reference values and predicted equations of CPX variables in this study may provide a more appropriate framework to interpret the response to maximal ramp incremental cycle ergometry in the Chinese adult population.

Work rate has a direct impact on the systolic blood pressure (SBP) during aerobic exercise, which may be challenging in the evaluation of the SBP response in athletes reaching high work rates. We aimed to investigate the exercise SBP response in endurance athletes in relation to oxygen uptake (VO2), work rate and to recent reference equations for exercise SBP in the general population. Endurance athletes with a left-ventricular end-diastolic diameter above the reference one performed a maximal bicycle cardiopulmonary exercise test. The increase in SBP during exercise was divided by the increase in VO2 (SBP/VO2 slope) and in Watts, respectively (SBP/W slope). The maximum SBP (SBPmax) and the SBP/W slope were compared to the predicted values. In total, 27 athletes (59% men) were included; mean age, 40 +/- 10 years; mean VO2max, 50 +/- 5 mL/kg/min. The mean SBP/VO2 slope was 29.8 +/- 10.2 mm Hg/L/min, and the mean SBP/W slope was 0.27 +/- 0.08 mm Hg/W. Compared to the predicted normative values, athletes had, on average, a 12.2 +/- 17.6 mm Hg higher SBPmax and a 0.12 +/- 0.08 mm Hg/W less steep SBP/W slope (p < 0.01 and p < 0.001, respectively). In conclusion, the higher SBPmax values and the less steep SBP/W slope highlight the importance of considering work rate when interpreting the SBP response in endurance athletes and suggest a need for specific normative values in athletes to help clinicians distinguish physiologically high maximal blood pressure from a pathological blood pressure response. Funding Agencies|Swedish Research Council for Sport Science [2017-0017, 2018-0187]; Swedish Heart Lung Foundation [20160677]

Marko, D, Bahenský, P, Snarr, RL, and Malatova, R. V[Combining Dot Above]O2peak Comparison of a treadmill vs. cycling protocol in elite teenage competitive runners, cyclists, and swimmers. J Strength Cond Res XX(X): 000-000, 2021-The purpose of this study was to compare the cardiorespiratory and metabolic responses of a maximal graded exercise test (GXT) on a treadmill and cycle ergometer in elite-level, youth competitive athletes. Thirty-one athletes (11 distance runners, 11 mountain-bike cyclists, and 9 long-distance swimmers) were randomly selected to complete either a running or cycling GXT on the first day, followed by the alternative 72 hours apart. The initial work rate for each GXT was set at 50% of the individuals' previously established V[Combining Dot Above]O2peak to elicit fatigue within 8-12 minutes. For the treadmill protocol, speed was increased by 1 km·h-1 each minute, with a constant 5% grade, until volitional fatigue. Cycle ergometer work rate was increased by 30 W every minute until volitional fatigue or the inability to maintain proper cadence (i.e., 100 ± 5 rev·min-1). Throughout both testing sessions, V[Combining Dot Above]O2peak, heart rate [HR] peak, breathing frequency (BF), tidal volume (VT), and minute ventilation (VE) were assessed and used to compare within-sport differences. Runners displayed a higher V[Combining Dot Above]O2peak (∼7%; d = 0.92), HRpeak (4%; d = 0.77), VE (6%; d = 0.66), and BF (12%; d = 0.62) on the treadmill vs. cycle. However, the cycling group demonstrated a greater V[Combining Dot Above]O2peak (∼8%; d = 0.92), VT (∼14%; d = 0.99), and VE (∼9%; d = 0.78) on the cycle, despite no change in HRpeak. For swimmers, the treadmill GXT elicited higher values in V[Combining Dot Above]O2peak (∼5%; d = 0.75), BF (∼11.5%; d = 0.78), and HRpeak (3%; d = 0.69). Collectively, these findings indicate that exercise mode may greatly affect physiological outcome variables and should be considered before exercise prescription and athletic monitoring.

Background: Prolonged exercise leads to progressive water and electrolyte loss from the body as sweat is secreted to promote heat loss. The rate of sweating depends on many factors and is increased in proportion to the work rate and the environmental temperature and humidity. Prolong exercise could lead to an alteration in electrolyte concentrations and this could lead to deleterious effects in the body. Aim: To determine the effect of Physical Exercise on Serum Electrolytes Urea and Creatinine in undergraduate footballers in Anambra State. Method: Six football teams comprising of 11 players each were grouped into 3 sets. Each set containing 22 players was allowed to play football for at least 2hours with a 15 minutes break interval. They were allowed to take only 250mls water during this exercising period. Blood samples were collected from all the subjects prior to the exercise from anticubital veins with the subjects in sitting position. Post-Exercise blood Samples were collected within 5 minutes after and 2hrs after the exercise. The blood samples were also analyzed for serum electrolytes, urea and creatinine. Blood sample for calcium was collected after removing the tourniquet for 2 minutes. The serum concentrations of sodium, potassium, bicarbonate, chloride and calcium were estimated using ion-selective electrodes while urea and creatinine were estimated using standard colorimetric methods. Results: There was no significant difference in mean concentrations of serum electrolytes (Na+, K+, Cl- and HCO3-) profile levels in pre-exercising subjects when compared with the post-exercising period. (P> 0.05). However, the mean levels of Ca2+ increased significantly in post-exercise period when compared with the pre-exercising condition (P < 0.05). The findings of this work suggest that short duration of exercise does not alter significantly the serum electrolytes.

Background: The reference values of young athletes for cardiopulmonary exercise testing are lacking. Expert opinions encourage production of local values specific for certain population. Patients and methods: The study population consisted of 136 healthy male caucasian athletic children and adolescents coming from one specific football school in northern Slovakia. Exercise testing with continuous electrocardiography was performed, and ventilatory parameters, oxygen uptake (VO2), and carbon dioxide (CO2) production were measured continuously with a respiratory gas analysis system. Results: Peak VO2max/kg was changing very little across the childhood, whereas the peak work rate, heart rate and O2Pulse were. Linear regression analysis showed a significant effect of age on VE/VCO2. Conclusion: This work provides a reference values for the most important cardiopulmonary variables that can be obtained during cardiopulmonary exercise testing in athletic children.

The aims of this study were to compare four different critical power model's ability to ascertain critical power and W′ in elite road cyclists, while making comparison to power output at respiratory compensation point, work rate (J·sec−1) at Wmax, and the work done above critical power during the Wmax test in relation to the W’. Ten male, elite endurance cyclists (V̇O2max ​= ​71.9 ​± ​5.9 ​ml ​kg−1·min−1) all familiar with critical power testing, participated in 3 testing sessions comprising 1. 15-s isokinetic (130 ​rpm) sprint, 1-min time trial, a ramp test to exhaustion, 2–3. a 4-min and/or 10-min self-paced maximal time trial separated by at least 24-h but limited to a 3-week period. The main findings show that all critical power models provided different W’ (F(1.061,8.486) ​= ​39.07, p ​= ​0.0002) and critical powers (F(1.022,8.179) ​= ​32.31, p ​= ​0.0004), while there was no difference between each model's critical power and power output at respiratory compensation point (F(1.155, 9.243) ​= ​2.72, p ​= ​0.131). Differences between models or comparisons with respiratory compensation point were deemed not clinically useful in the provision of training prescription or performance monitoring if the aim is to equal work rate at compensation point. There was also no post-hoc difference between work completed at Wmax (kJ) (p ​= ​0.890) and W′ using the nonlinear-3 model. Further research is required to investigate the physiological markers of intensity associated with respiratory compensation point and critical power work rate and the bioenergetic contribution to W’., Graphical abstract Image 1, Highlights • Critical power models provide different critical power and W′ values. • Critical power from all models was not different to respiratory compensation point. • Critical power models do not provide clinically useful work rates if alternative to respiratory compensation is sort. • More research required to investigate bioenergetics of W’.

Objective To investigate cerebral oxygenation (Cox) responses as well as respiratory (Res) and active peripheral muscle (Pm) O2 delivery during high-intensity cycling exercise and contrast responses between patients with coexistent chronic obstructive pulmonary disease (COPD)-heart failure (HF) and HF alone. Methods Cross-sectional study involving 11 COPD-HF and 11 HF patients. On two different days, patients performed maximal incremental cardiopulmonary exercise testing (CPET) and constant load exercise on a cycle ergometer until the limit of tolerance (Tlim). The high-intensity exercise session was 80% of the peak CPET work rate. Relative blood concentrations of oxyhemoglobin ([O2Hb]), deoxyhemoglobin ([HHb]) of Res, Pm (right vastus lateralis) and Cox (pre-frontal) were measured using near infrared spectroscopy. Results We observed a greater decrease in [O2Hb] at a lower Tlim in COPD-HF when compared to HF (P

Purpose Cardiovascular regulation during exercise, described using time series analysis, is expected to be attenuated after bed rest (BR) and this effect will be dampened by a reactive jumps countermeasure. Methods Twenty subjects (29 ± 6 years, 23.6 ± 1.7 kg m−2) were tested on a cycle ergometer 9 days (BDC-9) before the beginning of BR as well as 2 (R + 2) and 13 days (R + 13) after the end of BR, applying moderate pseudo-random binary (PRBS) work rate changes. Heart rate (HR) and mean arterial blood pressure (mBP) were measured beat-to-beat and interpolated to 1 s intervals. HR and mBP were cross-correlated [CCF(HR-mBP)] during the PRBS. Eleven subjects participated in a reactive jump countermeasure (JUMP) during the BR period, the other part of the group served as control group (CTRL). Results In the CTRL group, significantly lower CCF(HR-mBP) values during BDC-9 were observed compared to R + 2 during the lags 20–25 s and significantly higher values during the lags − 39 s to − 35 s. In the JUMP group, significantly lower CCFs were only observed at R + 2 compared with BDC-9 during the lags 23 s and 24 s, whereas the CCFs for BDC-9 were significantly higher at several lags compared with R + 13. Conclusion Attenuations in the regulation of the cardiovascular system during cycling exercise after BR were found in the CTRL group of the RSL study. Cardiovascular regulation in the JUMP group was improved compared to values before the beginning of BR, suggesting the effectiveness of the reactive jumps countermeasure to mitigate the deleterious effects of prolonged BR.

New findings What is the central question of this study? How does sternocleidomastoid blood flow change in response to increasing ventilation and whole-body exercise intensity? What is the main finding and its importance? Sternocleidomastoid blood flow increased with increasing ventilation. For a given ventilation, sternocleidomastoid blood flow was lower during whole-body exercise compared to resting hyperpnoea. These findings suggest that locomotor muscle work exerts an effect on respiratory muscle blood flow that can be observed in the sternocleidomastoid. Abstract Respiratory muscle work influences the distribution of blood flow during exercise. Most studies have focused on blood flow to the locomotor musculature rather than the respiratory muscles, owing to the complex anatomical arrangement of respiratory muscles. The purpose of this study was to examine how accessory respiratory (i.e. sternocleidomastoid, and muscles in the intercostal space) muscle blood flow changes in response to locomotor muscle work. Seven men performed 5 min bouts of constant load cycling exercise trials at 30%, 60% and 90% of peak work rate in a randomized order, followed by 5 min bouts of voluntary hyperpnoea (VH) matching the ventilation achieved during each exercise (EX) trial. Blood-flow index (BFI) of the vastus lateralis, sternocleidomastoid (SCM) and seventh intercostal space (IC) were estimated using near-infrared spectroscopy and indocyanine green and expressed relative to resting levels. BFISCM was greater during VH compared to EX (P = 0.002) and increased with increasing exercise intensity (P = 0.036). BFISCM reached 493 ± 219% and 301 ± 215% rest during VH and EX at 90% peak work rate, respectively. BFIIC increased to 242 ± 178% and 210 ± 117% rest at 30% peak work rate during VH and EX, respectively. No statistically significant differences in BFIIC were observed with increased work rate during VH or EX (both P > 0.05). Moreover, there was no observed difference in BFIIC between conditions (P > 0.05). BFISCM was lower for a given minute ventilation during EX compared to VH, suggesting that accessory respiratory muscle blood flow is influenced by whole-body exercise.

Astorino, TA, Oriente, C, Peterson, J, Alberto, G, Castillo, EE, Vasquez-Soto, U, Ibarra, E, Guise, V, Castaneda, I, Marroquin, JR, Dargis, R, and Thum, JS. Higher peak fat oxidation during rowing vs. cycling in active men and women. J Strength Cond Res XX(X): 000-000, 2020-This study compared fat and carbohydrate oxidation (CHOOx) between progressive rowing and cycling. Initially, 22 active healthy adults (age = 27 ± 8 years) performed incremental cycling and rowing to volitional fatigue to assess maximal oxygen uptake (V[Combining Dot Above]O2max) and maximal heart rate (HRmax). The order of 2 subsequent sessions was randomized, performed 2 hours postmeal, and included a warm-up followed by three 8-minute stages of rowing or cycling at 60-65, 70-75, and 80-85 %HRmax. During exercise, power output was modified to maintain work rate in the desired range. Gas exchange data and blood samples were obtained to measure fat and CHOOx and blood lactate concentration. Fat oxidation (FOx) increased during exercise (p < 0.001) and there was a main effect of mode (p = 0.03) but no modeXintensity interaction (p = 0.33). Peak FOx was higher in response to rowing vs. cycling (0.23 ± 0.09 g·min vs. 0.18 ± 0.07 g·min, p = 0.01). Carbohydrate oxidation increased during exercise (p < 0.001) but there was no effect of mode (p = 0.25) or modeXintensity interaction (p = 0.08). Blood lactate concentration was lower (p = 0.007) at the end of rowing vs. cycling (3.1 ± 1.0 mM vs. 3.9 ± 1.6 mM, d = 1.1). Prolonged rowing having equivalent calorie expenditure and intensity vs. cycling elicits higher peak FOx, which is likely attributed to greater muscle mass used during rowing.

Purpose Few data exist on the descriptions of LV myocardial mechanics and reserve during dynamic exercise of adolescent athletes. The aim of this study was to describe the LV myocardial and cardiopulmonary changes during exercise using 2-D strain deformation imaging. Methods Elite adolescent male football players (n = 42) completed simultaneous cardiopulmonary exercise testing (CPET) and exercise echocardiography measurement of LV myocardial deformation by 2-D strain imaging. LV longitudinal and circumferential 2-D strain and strain rates were analyzed at each stage during incremental exercise to a work rate of 150 W. Additionally, exercise LV myocardial deformation and its relation to metabolic exercise parameters were evaluated at each exercise stage and in recovery using repeated measures ANOVA, linear regression and paired t tests. Results LV peak systolic baseline 2-D strain (longitudinal: − 15.4 ± 2.5%, circumferential: − 22.5 ± 3.1%) increased with each exercise stage, but longitudinal strain plateaued at 50 W (mean strain reserve − 7.8 ± 3.0) and did not significantly increase compared to subsequent exercise stages (P > 0.05), whilst circumferential strain (mean strain reserve − 11.6 ± 3.3) significantly increased (P 2 and O2 pulse (P Conclusion This study describes LV myocardial deformation dynamics by 2-D strain and provides reference values for LV myocardial strain and strain rate during exercise in adolescent footballers. It found important differences between LV longitudinal and circumferential myocardial mechanics during exercise and introduces a methodology that can be used to quantify LV function and cardiac reserve during exercise in adolescent athletes.

The biomechanical differences between cyclists with a high compared with a low blood lactate threshold (HLT; 80% VO2max vs LLT, 70% VO2max) have yet to be completely described. We hypothesize that HLT cyclists reduce the stress placed on the knee extensor muscles by increasing the relative contribution from the hip joint during high-intensity cycling. Sixteen well-trained endurance athletes, with equally high VO2max while cycling and running completed submaximal tests during incremental exercise to identify lactate threshold ( $${\text{LT}}_{{V{\text{O}}_{2} }}$$ ) while running and cycling. Subjects were separated into two groups based on % VO2max at LT during cycling (high; HLT: 80.2 ± 2.1% VO2max; n = 8) and (LLT: 70.3 ± 2.9% VO2max; n = 8; p 0.05) while running. While cycling in LLT, knee joint absolute power increased with work rate (p 0.05). The HLT generated significantly greater relative hip power compared with the LLT group at 90% VO2max (p

This study evaluated the effects of age on physical and technical game performance for different positions in professional basketball players. In this cross-sectional study, a total of 25,523 individual match observations were undertaken on players from the 2018-19 NBA season. The players were classified into four age groups (19-22 years, 23-25 years, 26-29 years, and 30-42 years). Differences in physical and technical match performance were analysed for the following variables: distance covered, average speed, minutes played, points scored and playing efficiency. The results showed that players older than 30 covered shorter distance and had lower average speed than younger players, that guards and forwards older than 26 played more minutes per game than younger ones, and that guards older than 26 scored more points and were more efficient than younger one, while centres age 23-25 scored more points per games than centres older than 30. In conclusion, physical performance declined with age, and while playing time and technical performance generally remained stable or increased, especially for guards. However, there was some evidence of decline for centres.

New findings What is the central question of this study? What are the dynamic characteristics of cerebrovascular carbon dioxide reactivity and the central respiratory chemoreflex? What is the main finding and its importance? The transfer function gain from the end-tidal partial pressure of carbon dioxide to cerebral blood flow or ventilation decreased in the high frequency range at rest and during exercise. These findings indicate that the dynamic characteristics of both systems were not constant in all frequency ranges, and this trend was not modified by exercise. Abstract The purpose of this study was to examine the dynamic characteristics of cerebrovascular reactivity and ventilatory response to change in arterial CO2 in all frequency ranges at rest using frequency domain analysis, and also to examine whether this is modified by dynamic exercise as with the traditionally determined cerebrovascular CO2 reactivity. In nine healthy young subjects, at rest and during exercise (cycling exercise at constant predetermined work rate corresponding to a V O 2 level of 0.90 l min-1 ), the dynamic characteristics of cerebrovascular CO2 reactivity and the central respiratory chemoreflex were assessed by transfer function analysis using a binary white-noise sequence (0-7% inspired CO2 fraction) from the end-tidal partial pressure of CO2 ( P ETC O 2 ) to the mean middle cerebral artery mean blood velocity (MCA Vm ) or minute ventilation ( V E ), respectively. In the high frequency range, both transfer function gains decreased but, interestingly, the cut-off frequency in the transfer function gain from P ETC O 2 to MCA Vm response was higher than that from P ETC O 2 to V E response at rest (0.024 vs. 0.015 Hz) and during exercise (0.030 vs. 0.011 Hz), indicating that cerebrovascular CO2 reactivity or central respiratory chemoreflex was not constant in all frequency ranges, and this trend was not modified by exercise. These findings suggest that dynamic characteristics of the cerebrovascular CO2 reactivity or central chemoreflex need to be assessed to identify the whole system because the traditional method cannot identify the property of time response of these systems.

To investigate whether performing resistance exercise in hypoxia augments physiological and perceptual responses, and if altering work-rate by performing repetitions to failure compared to sub-maximally increases the magnitude of these responses. Twenty male university students (minimum of 2 year resistance training experience) completed four sessions, two in hypoxia (fraction of inspired oxygen [FiO2] = 0.13), and two in normoxia (FiO2 = 0.21). For each condition, session one comprised three sets to failure of shoulder press and bench press (high work-rate session), while session two involved the same volume load, distributed over six sets (low work-rate session). Muscle oxygenation (triceps brachii), surface electromyographic activity (anterior deltoid, pectoralis major, and triceps brachii), heart rate (HR), and arterial blood oxygen saturation were recorded. Blood lactate concentration ([Bla−]) was recorded pre-exercise and 2 min after each exercise. Muscle thickness was measured pre- and post-exercise via ultrasound. Muscle oxygenation values during sets and inter-set rest periods were lower in hypoxia vs normoxia (p = 0.001). Hypoxia caused greater [Bla−] during the shoulder press of failure sessions (p = 0.003) and both shoulder press (p = 0.048) and bench press (p = 0.005) of non-failure sessions. Hypoxia increased HR during non-failure sessions (p

Among patients with multiple sclerosis (MS), the impairment of exercise tolerance is closely related to disability. Maximal oxygen uptake (VO2max ) is the gold standard to assess exercise tolerance in healthy subjects (HS). Among patients with MS, the accuracy of VO2max measurement is often impaired because the patients are unable to reach the maximal exercise intensity due to interdependent factors linked to the disease (such as pathological fatigue, pain, lack of exercise habit, and lack of mobility). This study assesses the accuracy of simplified indices for assessing exercise tolerance, which are more suitable in patients with MS. They are simple in the way they are either measurable during submaximal exercise (oxygen uptake efficiency slopes (OUES), physical working capacity at 75% of maximal heart rate (PWC75% ), oxygen consumption at a respiratory exchange ratio of 1 (VO2 @RER1)) or not based on gas exchange analysis (peak work rate (PWR)-based predictive equation and PWC75% ). All indices were significantly lower in the MS group compared to the HS group (P .70, P < .001) with VO2peak , in both groups, without difference between groups. PWR-based prediction of VO2peak showed a standard error of the estimate of 315 mL min-1 in HS and 176 mL min-1 in MS. PWC75% did not correlate to VO2peak in neither group. These findings suggest an impairment of exercise tolerance functions in mildly disabled persons with MS, independently from other factors. Submaximal indices involving gas exchange analysis or peakWR-based estimation of VO2peak are usable to accurately assess exercise tolerance.

Key points Exercise intolerance is common in chronic obstructive pulmonary disease (COPD) patients. In patients with COPD, we compared an interval exercise (IE) protocol (alternating 30 s at 100% peak work rate (WRpeak ) with 30 s at 50% WRpeak ) with moderate-intensity constant-load exercise (CLE) at 75% WRpeak , which yielded the same work rate. Exercise endurance time and total work output were almost twice as high for IE than CLE. At exercise isotime (when work completed was the same between IE and CLE), IE was associated with less dynamic hyperinflation, lower blood lactate concentration, and greater respiratory and locomotor muscle oxygenation, but there were no differences in ventilation or cardiac output. However, at the limit of tolerance for each modality, dynamic hyperinflation was not different between IE and CLE, while blood lactate remained lower and muscle oxygenation higher with IE. Taken together, these findings suggest that dynamic hyperinflation and not muscle-based factors dictate the limits of tolerance in these COPD patients. Abstract The relative importance of ventilatory, circulatory and peripheral muscle factors in determining tolerance to exercise in patients with chronic obstructive pulmonary disease (COPD) is not known. In 12 COPD patients (forced expiratory volume in one second: 58 ± 17%pred.) we measured ventilation, cardiac output, dynamic hyperinflation, local muscle oxygenation, blood lactate and time to exhaustion during (a) interval exercise (IE) consisting of 30 s at 100% peak work rate alternating with 30 s at 50%, and (b) constant-load exercise (CLE) at 75% peak work rate, designed to produce the same average work rate. Exercise time was substantially longer during IE than CLE (19.5 ± 4.8 versus 11.4 ± 2.1 min, p = 0.0001). Total work output was therefore greater during IE than CLE (81.3 ± 27.7 versus 48.9 ± 23.8 kJ, p = 0.0001). Dynamic hyperinflation (assessed by changes from baseline in inspiratory capacity, ΔIC) was less during IE than CLE at CLE exhaustion time (isotime, p = 0.009), but was similar at exhaustion (ΔICCLE : -0.38 ± 0.10 versus ΔICIE : -0.33 ± 0.12 l, p = 0.102). In contrast, at isotime, minute ventilation, cardiac output and systemic oxygen delivery did not differ between protocols (P > 0.05). At exhaustion in both protocols, the vastus lateralis and intercostal muscle oxygen saturation were higher in IE than CLE (p = 0.014 and p = 0.0002, respectively) and blood lactate concentrations were lower (4.9 ± 2.4 mmol l-1 versus 6.4 ± 2.2 mmol l-1 , p = 0.039). These results suggest that (1) exercise tolerance with COPD is limited by dynamic hyperinflation; and (2) cyclically lower (50%) effort intervals in IE help to preserve muscle oxygenation and reduce metabolic acidosis compared with CLE at the same average work rate; but these factors do not appear to determine time to exhaustion.

KEY POINTS During exercise, blood flow to working skeletal muscle increases in parallel with contractile activity such that oxygen delivery is sufficient to meet metabolic demand. K+ released from active skeletal muscle fibres could facilitate vasodilatation in proportion to the degree of muscle fibre recruitment. Once released, K+ stimulates inwardly rectifying K+ (KIR ) channels on the vasculature to elicit an increase in blood flow. In the present study, we demonstrate that KIR channels mediate the rapid vasodilatory response to an increase in exercise intensity. We also show that KIR channels augment vasodilatation during exercise which demands greater muscle fibre recruitment independent of the total amount of work performed. These results suggest that K+ plays a key role in coupling the magnitude of vasodilatation to the degree of contractile activity. Ultimately, the findings from this study help us understand the signalling mechanisms that regulate muscle blood flow in humans. ABSTRACT Blood flow to active skeletal muscle is augmented with greater muscle fibre recruitment. We tested whether activation of inwardly rectifying potassium (KIR ) channels underlies vasodilatation with elevated muscle fibre recruitment when work rate is increased (Protocol 1) or held constant (Protocol 2). We assessed forearm vascular conductance (FVC) during rhythmic handgrip exercise under control conditions and during local inhibition of KIR channels (intra-arterial BaCl2 ). In Protocol 1, healthy volunteers performed mild handgrip exercise for 3 min, then transitioned to moderate intensity for 30 s. BaCl2 eliminated vasodilatation during the first contraction at the moderate workload (ΔFVC, BaCl2 : -1 ± 17 vs. control: 30 ± 28 ml min-1 100 mmHg-1 ; n = 9; P = 0.004) and attenuated the 30 s area under the curve by 56 ± 14% (n = 9; P

BACKGROUND AND OBJECTIVE The efficacy of supplemental oxygen during exercise remains unclear for patients with IPF, as there have been conflicting results from recent prospective studies with small sample sizes. METHODS This prospective, single-blind, randomized, crossover trial evaluated the efficacy of supplemental oxygen compared with placebo air during exercise in consecutive patients with IPF without resting hypoxaemia at initial evaluation. Patients with

Background: Idiopathic pulmonary fibrosis (IPF) is a progressive disease associated with significant dyspnea and limited exercise capacity. This systematic review aimed to synthesize evidence of exercise interventions during pulmonary rehabilitation that aim to improve exercise capacity, dyspnea, and health- related quality of life (HRQL) in IPF patients. Methods: Searches were performed in MEDLINE, Embase, CENTRAL, SPORTDiscus, PubMed and PEDro from inception to January 2019 using search terms for: (I) participants: ‘IPF or interstitial lung disease’; (II) interventions: ‘aerobic training or resistance training or respiratory muscle training’; and (III) outcomes: ‘exercise capacity or dyspnea or health-related quality of life’. Two reviewers independently screened titles, abstracts and full texts to identify eligible studies. Methodological quality of studies was assessed using the Downs and Black checklist and meta-analyses were performed. Results: Of 1,677 articles identified, 14 were included (four randomized controlled trials and 10 prospective pre-post design studies) that examined 362 patients receiving training and 95 control subjects. Exercise capacity was measured with the 6-minute walk distance, peak oxygen consumption, peak work rate, or endurance time for constant work rate cycling, which increased after exercise [aerobic exercise; aerobic and breathing exercises; aerobic and inspiratory muscle training (IMT) exercises] compared to the control groups. Dyspnea scores improved after aerobic and breathing exercises. HRQL also improved after aerobic exercise training alone or combined with breathing exercises. Aerobic training alone or combined with IMT or breathing exercises improved exercise capacity. Conclusions: Breathing exercises appears to complement exercise training towards improved dyspnea and HRQL in patients with IPF.

The purpose of this study was to explore the respiratory response of acute interval and continuous exercise (CE) of low and high intensity. Fourteen recreational athletes (7 men and 7 women; VO2max = 35.7 ± 6.1 mlkg-1min-1) performed a bout of continuous and a bout of interval exercise (IE) both consisted of 5-min cycling at low intensity [80% of the power output (W) of the predetermined gas exchange threshold (GET) (80%WGET)] and 5-min cycling at high intensity {WGET plus the work rate corresponding to 50% of the difference between peak power output (PPO) at oxygen uptake (VO2max) test and the WGET [WGET + 0.50 Δ(PPO - WGET)]}. CE compared to IE induced significant higher heart rate and ventilation as well as significant higher levels of mouth occlusion pressure for 0.1 s (P0.1) (P < 0.05) during low and high intensities. Our results indicate that CE stimulates respiration more than IE when the exercise is performed at the same relative intensity.

A study was conducted on labour productivity in dairy cattle farms that breed Black-and-White cows. The study encompassed 90 farms, thus including 6471 cows. The farms were divided into four groups: small – 8 farms with an average of 3.6 cows; medium – 32 farms with an average of 22.9 cows; large – 32 farms with an average of 74.2 cows; and huge – 18 farms with 185.3 cows per farms. The results of the study indicated that large and huge farms are distinguished by high labour productivity. The income from production, profit, milk quantities, and the cost of one annual work unit (AWU) and a man-hour were several times higher compared to small and medium farms. Production was organised at a much better technological level, which was a contributing factor towards high-quality and competitive milk production. A recommendation to the small and medium farms would be to grow larger, improve their selection, and develop technologically.

Objective Continuous physiological measurements during a laboratory-based exercise test can provide physiological biomarkers, such as heart rate (HR) and oxygen uptake (V̇O2) kinetics, that carry clinically relevant information. In contrast, it is not clear how continuous data generated by wearable devices during daily-life routines could provide meaningful biomarkers. We aimed to determine whether valid HR and V̇O2 kinetics can be obtained from measurements with wearable devices during outdoor walks in patients with chronic obstructive pulmonary disease (COPD). Methods HR (Polar Belt) and V̇O2(METAMAX3B) were measured during 93 physical activity transitions performed by eight patients with COPD during three different outdoor walks (ntr = 77) and a 6-minute walk test (ntr = 16). HR and V̇O2 kinetics were calculated every time a participant started a walk, finished a walk or walked upstairs. HR and V̇O2 kinetics were considered valid if the response magnitude and model fit were adequate, and model parameters were reliable. Results Continuous measurements with wearable devices provided valid HR kinetics when COPD patients started or finished (range 63%–100%) the different outdoor walks and valid V̇O2 kinetics when they finished (range 63%–100%) an outdoor walk. The amount of valid kinetics and kinetic model performance was comparable between outdoor walks and a laboratory-based exercise test ( p > .05). Conclusion We envision that the presented approach could improve telemonitoring applications of patients with COPD by providing regular, unsupervised assessments of HR kinetics during daily-life routines. This could allow to early identify a decline in the patients’ dynamic physiological functioning, physical fitness and/or health status.

BACKGROUND To determine the trustworthiness of graded exercise test to exhaustion (GXT) to assess maximal oxygen uptake ( V˙O2max ) in metabolic syndrome individuals with obesity and poor cardiorespiratory fitness. METHODS V˙O2max was assessed in 100 metabolic syndrome adults (57 ± 8 years; 34% women), with obesity (BMI 32 ± 5 kg·m-2 ) using GXT followed by supramaximal constant-load verification test (VerT) at 110% of maximal GXT work rate. V˙O2 data from GXT and VerT were compared using paired t test and plotted for Bland-Altman analysis. GXT sensitivity and specificity to detect V˙O2max were also calculated. RESULTS Seventy individuals did not achieve V˙O2 plateau during GXT. GXT underestimated V˙O2max in 40 subjects. In these subjects, the magnitude of V˙O2max underestimation with GXT was 9% (167 mLO2 ·min-1 ; P

The dissociation between constant work rate of O2 uptake (V̇o2) and ramp V̇o2 at a given work rate might be mitigated during slowly increasing ramp protocols. This study characterized the V̇o2 dynamics in response to five different ramp protocols and constant-work-rate trials at the maximal metabolic steady state (MMSS) to characterize 1) the V̇o2 gain (G) in the moderate, heavy, and severe domains, 2) the mean response time of V̇o2 (MRT), and 3) the work rates at lactate threshold (LT) and respiratory compensation point (RCP). Eleven young individuals performed five ramp tests (5, 10, 15, 25, and 30 W/min), four to five time-to-exhaustions for critical power estimation, and two to three constant-work-rate trials for confirmation of the work rate at MMSS. G was greatest during the slowest ramp and progressively decreased with increasing ramp slopes (from ~12 to ~8 ml·min−1·W−1, P < 0.05). The MRT was smallest during the slowest ramp slopes and progressively increased with faster ramp slopes (1 ± 1, 2 ± 1, 5 ± 3, and 10 ± 4, 15 ± 6 W, P < 0.05). After “left shifting” the ramp V̇o2 by the MRT, the work rate at LT was constant regardless of the ramp slope (~150 W, P > 0.05). The work rate at MMSS was 215 ± 55 W and was similar and highly correlated with the work rate at RCP during the 5 W/min ramp ( P > 0.05, r = 0.99; Lin’s concordance coefficient = 0.99; bias = −3 W; root mean square error = 6 W). Findings showed that the dynamics of V̇o2 (i.e., G) during ramp exercise explain the apparent dichotomy existing with constant-work-rate exercise. When these dynamics are appropriately “resolved”, LT is constant regardless of the ramp slope of choice, and RCP and MMSS display minimal variations between each other. NEW & NOTEWORTHY This study demonstrates that the dynamics of V̇o2 during ramp-incremental exercise are dependent on the characteristics of the increments in work rate, such that during slow-incrementing ramp protocols the magnitude of the dissociation between ramp V̇o2 and constant V̇o2 at a given work rate is reduced. Accurately accounting for these dynamics ensures correct characterizations of the V̇o2 kinetics at ramp onset and allows appropriate comparisons between ramp and constant-work-rate exercise-derived indexes of exercise intensity.

Introduction Patients with chronic obstructive pulmonary disease (COPD) are at an increased risk of cardiovascular comorbidities such as pulmonary hypertension or heart failure. Impaired cardiovascular function often has a significant impact on patients with COPD. Oxygen pulse (O2P) is a surrogate for stroke volume. However, studies regarding O2P, health-related quality of life (HRQL), and exercise capacity in patients with COPD are lacking. We aimed to confirm the association between O2P, HRQL, exercise capacity, severe exacerbation of COPD, and other parameters in exercise testing. Materials and methods This study included 79 patients with COPD who underwent lung function testing, a cardiopulmonary exercise test (CPET), Borg Dyspnea Scale evaluation, completion of the St. George's Respiratory Questionnaire, and echocardiography. Cardiovascular comorbidities, COPD-related hospitalizations, and emergency room visits were recorded. We compared these parameters between two groups of patients: those with normal peak O2P and those with impaired peak O2P. The relationships of peak O2P with CPET and lung function were analyzed using simple linear regression. Results Patients with normal peak O2P had higher exercise capacity (peak oxygen uptake and work rate), better HRQL, lower dyspnea score, lower COPD-related hospitalizations, and higher circulatory and ventilator parameters than patients with impaired peak O2P. According to a simple linear regression analysis, the anaerobic threshold (AT) and forced expiratory volume in one second (FEV1) showed a significant association with peak O2P, and the Pearson correlation coefficients (Pearson's r) were 0.756 and 0.461, respectively. Conclusion Peak O2P has a significant impact on exercise capacity, HRQL, dyspnea, COPD-related hospitalization, and circulatory and ventilatory functions in patients with COPD. The AT and FEV1 have strong and moderate associations with peak O2P, respectively. Therefore, peak O2P is an important indicator of disease severity for patients with COPD.

Purpose: To investigate fluctuations in speed, work rate, and heart rate (HR) when cross-country ski skating across varying terrains at different endurance-training intensities. Methods: Seven male junior Norwegian skiers performed maximal-speed (Vmax) tests in both flat and uphill terrains. Thereafter, 5-km sessions at low (LIT), moderate (MIT), and high intensity (HIT) were performed based on their own perception of intensity while monitored by a global navigation satellite system with integrated barometry and accompanying HR monitor. Results: Speed, HR, and rating of perceived exertion gradually increased from LIT to MIT and HIT, both for the total course and in flat and uphill terrains (all P P P Conclusions: Cross-country ski training across varying terrains is clearly interval based in terms of speed, external work rate, and metabolic intensity for all endurance-training intensities. Although work rate and HR were highest in uphill terrain at all intensities, the utilization of maximal work rate was higher in flat terrain. This demonstrates the large potential for generating external work rate when uphill skiing and the corresponding downregulation of effort due to the metabolic limitations.

STUDY DESIGN A prospective study. OBJECTIVE To investigate the factors associated with cardiopulmonary exercise testing (CPET) measurements in patients with adolescent idiopathic scoliosis (AIS). SUMMARY OF BACKGROUND DATA Patients with AIS display restrictive pulmonary dysfunction on pulmonary function testing (PFT). It remains unknown whether thoracic spinal deformity affects exercise performance. METHODS One hundred and sixty-eight patients with AIS from January 2014 to December 2019 were included. They underwent preoperative spinal radiological assessment, PFT, and CPET. The effects of the thoracic curve magnitude, body mass index, physical activity level and history of bracing on pulmonary function and exercise performance were analyzed. The Student t test and two-tailed Pearson test were used in data analysis. RESULTS We found significantly reduced forced expiratory volume in 1 s (FEV1) in patients with a larger magnitude of the proximal thoracic curve (P

One of the most important variables in cycling is the oxygen consumption (VO 2 ) and its maximal value (‘VO 2 max’). The latter is considered as an appropriate indicator of the cardio-respiratory fitness and provides interesting information for many applications in the sports medicine context, however, this variable is not easy to measure out of a laboratory. Hence, this paper presents an alternative approach to the estimation of VO 2 dynamics by means of fuzzy systems that use an input vector composed of three easy-to-obtain variables: Heart Rate, Work Rate, and Respiratory Rate measured in a clinical Cardiopulmonary-Exercise Testing. Two tuning strategies are compared: the well-known adaptive-network-based fuzzy inference system and an evolutionary fuzzy system based on the differential evolution algorithm. Experimental results showed that both tuning strategies are capable of providing competitive solutions in terms of several regression indices.

Electromyography (EMG) and mechanomyography (MMG) have been used to directly evaluate muscle function through the electromechanical aspect of muscle contraction. The purpose of this study was to establish new absolute indices to describe muscle contraction performance during dynamic exercise by combining EMG and displacement MMG (dMMG) measured simultaneously using our previously developed MMG/EMG hybrid transducer system. Study participants were eight healthy male non-athletes (controls) and eight male athletes. EMG and dMMG of the vastus medialis were measured for 30 s during four cycles of recumbent bicycle pedaling (30, 60, 90, and 120 W) and on passive joint movement. Total powers were calculated based on the time domain waveforms of both signals. Muscle contraction performance was verified with the slope of regression line (SRL) and the residual sum of squares (RSS) obtained from EMG and dMMG correlation. EMG and dMMG has increased with the work rate. Force and EMG were similar between groups, but dMMG showed a significant difference with load increase. Athletes had significantly higher SRL and significantly lower RSS than controls. The average value divided by SRL and RSS was higher in athletes than in controls. The indices presented by the combined approach of EMG and dMMG showed a clear contrast between the investigated groups and may be parameters that reflect muscle contraction performance during dynamic exercise.

In the present practice review, we will explain how to perform and interpret a cardiopulmonary exercise test (CPET) in heart failure patients. Specifically, we will explain why cycle ergometer should be preferred to treadmill, the type of protocol needed, and the ideal exercise duration. Thereafter, we will discuss how to interpret CPET findings and determine the parameters that should be included. We will focus specifically on: peak VO2 (absolute value and a percentage of its predicted value), exercise duration, respiratory exchange ratio, peak work rate, heart rate, O2 pulse, end-tidal carbon dioxide pressure (PetCO2), PetO2, and -if blood gas samples are obtained-dead space to tidal volume ratio. Moreover, we will discuss the physiological and clinical value of anaerobic threshold, respiratory compensation point, ventilation vs. VCO2 and VO2 vs. work relationships. Finally, attention will be dedicated to exercise-induced periodic breathing. We will also discuss when and why CPET should be integrated with other measurements in the so-called complex CPET. Specifically: a) when and how to use a complex non-invasive CPET, which integrates CPET measurements with non-invasive cardiac output determination, working muscle near-infrared spectroscopy, transthoracic echocardiography, thoracic ultrasound, and lung diffusion analysis; b) when and how to use a complex minimally invasive CPET, in which CPET is combined with esophageal balloon recordings or with serial arterial blood sampling for blood gas analysis; c) when and how to use a complex invasive CPET, which usually implies the presence of a Swan Ganz catheter in the pulmonary artery and an arterial line.

The purpose of this study was to determine the cardiovascular, thermoregulatory, and perceived exertion responses during 2 h of moderate intensity exercise in a combined high heat (38 °C, 40% relative humidity) and hypoxic (15% O2) environment. Ten healthy volunteers completed 2 h of treadmill walking at 40% of maximal oxygen uptake in four different conditions, each separated by approximately 1 week: (1) control, 23 °C/20.9% O2, (2) heat, 38 °C/20.9% O2, (3) hypoxia, 23 °C/15% O2, and (4) combined heat/hypoxia, 38 °C/15% O2. Compared to the responses seen in each condition alone, heart rate (HR) and core temperature (Tcore) showed an additive increase in the combined heat and hypoxic environment after 2 h of moderate intensity exercise. The most important new finding was that the mean rating of perceived exertion (RPE) increased synergistically 3.3 units when exercising in the combined high heat and hypoxic environment, compared to 1.9 units in the heat condition alone. The results suggest that RPE is a conscious perception of effort that plays a regulatory function to ensure that the work rate remains at an intensity that can be safely sustained, rather than simply a marker of exercise intensity. Such results also support previous anecdotal reports that exercise on hot days at altitude seem unusually difficult.

The aim of the study was to examine the associations between maximal and submaximal field tests with match physical activity and biological maturation in youth football players. Sixty-eight youth football players (U14, U15, U16, U17) performed maximal and submaximal field endurance tests. Biological maturity was estimated calculating the distance from peak height velocity (Y-PHV). Physical match activities were tracked using GPS units and players’ post-match rate of perceived exertion (RPE) was recorded. Mainly moderate associations were found between field tests and match activities. Large correlations were found between Yo-Yo Intermittent Recovery test level 1, distance covered at high and very high-speed running, the quantity of very high and maximal metabolic power running. Small to moderate associations between match activities and Y-PHV were observed. The magnitude of correlation between match activities and field tests increased from moderate to large when matches with an RPE>5 were considered. The results provide further evidence of the association between young football players’ aerobic performance and match work rate. Submaximal field tests demonstrate ecological validity and may constitute a practical alternative to performing maximal tests. Maturation was found to have a moderate effect on youth players’ match work rate.

A major concern of rehabilitation counselors is the likelihood of work following illness and the purpose of this paper is to determine the work rate of persons with neuromuscular conditions. A review of 38 published reports indicated the capacity for employment, but this varied according to the specific neuromuscular condition. A quantitative summary of previous studies that comprised a total of 2926 participants indicated that 1266 or 43.2% were working. Higher work rates were reported for studies where (a) the focus was on specific disorders rather than neuromuscular conditions in general or (b) where the participation rate was greater than 80%.

KEY POINTS The effect of combined inspiratory and expiratory muscle training on resting and reflexive cardiac function, as well as exercise capacity, in individuals with cervical spinal cord injury (SCI) is presently unknown. Six weeks of combined inspiratory and expiratory muscle training enhances both inspiratory and expiratory muscle strength in highly-trained athletes with cervical SCI with no significant effect on lung function. There was a significant decrease in left-ventricular filling and stroke volume at rest in response to 45° head-up tilt, which is irreversible by respiratory muscle training. Combined inspiratory and expiratory muscle training increased peak aerobic work rate and reduced end-expiratory lung volumes during exercise, which may have implications for left-ventricular filling during exercise. ABSTRACT To investigate the pulmonary, cardiovascular and exercise responses to combined inspiratory and expiratory respiratory muscle training (RMT) in athletes with tetraplegia, six wheelchair rugby athletes (five males and one female, aged 33 ± 5 years) completed 6 weeks of pressure threshold RMT, 2 sessions day-1 on 5 days week-1 . Resting pulmonary and cardiac function, exercise capacity, exercising lung volumes and field-based exercise performance were assessed at pre-RMT, post-RMT and after a 6-week no RMT period. RMT enhanced maximal inspiratory (pre- vs. post-RMT: -76 ± 15 to -106 ± 23 cmH2 O, P = 0.002) and expiratory (59 ± 26 to 73 ± 32 cmH2 O, P = 0.007) mouth pressures, as well as peak expiratory flow (6.74 ± 1.51 vs. 7.32 ± 1.60 L/s, P

The age of peak performance is likely to vary between sports and competitions, affected by the specific skills and attributes needed to succeed in the particular competition. However, no studies using modern tracking techniques have examined the effects of age on competitive match play performance. Thus, the purpose of this study was to evaluate the effects of age on match physical and technical performance using a large-scale analysis of match performance in professional soccer players. A total of 14 546 individual match observations were undertaken in the first German league (Bundesliga) during the 2012-2013, 2013-2014, and 2014-2015 seasons using a computerized tracking system (VISTRACK, by Impire Corp.). Differences in physical and technical match performance of soccer players were analyzed for the following variables: total distance covered, number of fast runs, number of sprints, and percentage of successful passes. Professional soccer players aged >30 years showed a significant lower performance in the total distance covered, the number of fast runs, and the number of sprints compared with younger players (≤30 years). Conversely, the player's ability to make successful passes increased with age. These effects were observed in all positional roles except wide midfielders. These findings may help coaches and managers to better understand the effects of age on match-related physical and technical performance and may have the potential to assist in decisions such as, when a new contract would be signed, the duration of the contract, the salary, or when to replace or transfer a player depending on their age.

New Findings What is the central question of this study? To what extent are the mechanical‐ventilatory responses to upper‐body exercise influenced by task‐specific locomotor mechanics? What is the main finding and its importance? When compared with lower‐body exercise performed at similar ventilations, upper‐body exercise was characterized by tidal volume constraint, dynamic lung hyperinflation and an increased propensity towards neuromechanical uncoupling of the respiratory system. Importantly, these responses were independent of respiratory dysfunction and flow limitation. Thus, the mechanical ventilatory responses to upper‐body exercise are attributable, in part, to task‐specific locomotor mechanics (i.e. non‐respiratory loading of the thorax). Abstract The aim of this study was to determine the extent to which the mechanical ventilatory responses to upper‐body exercise are influenced by task‐specific locomotor mechanics. Eight healthy men (mean ± SD: age, 24 ± 5 years; mass, 74 ± 11 kg; and stature, 1.79 ± 0.07 m) completed two maximal exercise tests, on separate days, comprising 4 min stepwise increments of 15 W during upper‐body exercise (arm‐cranking) or 30 W during lower‐body exercise (leg‐cycling). The tests were repeated at work rates calculated to elicit 20, 40, 60, 80 and 100% of the peak ventilation achieved during arm‐cranking (V˙E, UBE ). Exercise measures included pulmonary ventilation and gas exchange, oesophageal pressure‐derived indices of respiratory mechanics, operating lung volumes and expiratory flow limitation. Subjects exhibited normal resting pulmonary function. Arm‐crank exercise elicited significantly lower peak values for work rate, O2 uptake, CO2 output, minute ventilation and tidal volume (p

Objectives: Hyperbaric oxygen (HBO2) exposure may enhance cardiorespiratory fitness. Exercise training and HBO2 exposure stimulate mitochondrial biogenesis, increase capillary density, and induce adaptive antioxidant mechanisms. We hypothesized that an exercise regimen of sprint interval training (SIT) while breathing HBO2 would lead to a greater improvement in exercise performance compared to the same training breathing ambient air. Methods: Healthy long-term intermediate-altitude residents, ages 20-39 years, with normal spirometry and cardiorespiratory fitness were randomized to two groups: one performing six sessions of an SIT regimen over two weeks in a hyperbaric chamber (1.4 ATA [141.9 kPa], FiO2=1.0); the other performing under ambient pressure conditions (0.85 ATA [86.1 kPa], FiO2=0.21). Training effect was evaluated by comparing incremental cycle ergometry cardiopulmonary exercise testing before and after the training regimen. The primary outcome measure was peak oxygen consumption (V̇O2), while secondary outcomes included additional exercise parameters. The effect of study group on exercise parameters was assessed using two-factor repeated measures ANOVA. Results: Of 58 participants randomized, 49 completed the training program and all cardiopulmonary exercise tests (n=23 HBO2, n=26 ambient). Both groups experienced an increase in peak V̇O2: 8.1% HBO2 and 7.1% ambient; the differences were not significant (p=0.50). Secondary parameters of peak work rate and peak V̇E experienced a significantly higher change in the HBO2 group compared to the ambient group (p=0.05 and p=0.03, respectively). Conclusion: Cardiorespiratory fitness improved after a two-week SIT regimen, but improvement in peak V̇O2 was not significantly different between ambient and HBO2 groups.

It is well known that supplemental oxygen can increase aerobic power output during high-intensity and/or maximal efforts at moderate altitude, yet the effects on self-selected work rate during lower-intensity, submaximal exercise are unknown. We reasoned that if the degree of arterial oxygen saturation (SaO2) influences teleoanticipatory regulation of power output, supplemental oxygen given at moderate altitude would increase average power output during exercise performed at self-selected work rates corresponding to RPE 9 (very light) and 13 (somewhat hard).Twenty-three subjects (17 males, 6 females) completed one familiarization [fraction of inspired O2 (FIO2) = 0.209] and two blinded, experimental trials (FIO2 = 0.209 and FIO2 = 0.267). In each trial, subjects self-regulated their work rate on a cycle ergometer to maintain RPE 9 for 5 min and RPE 13 for 10 min, before performing an incremental step test to exhaustion (25 W·min). Oxygen consumption (V˙O2) and SaO2 via pulse oximetry (SpO2) were continuously monitored. Subjects were asked to guess the experimental condition after each stage of the protocol.Supplemental oxygen increased SpO2 throughout exercise (~4%; P0.001) and was associated with greater peak power output (4% ± 4%; P0.001) and V˙O2 (5% ± 10%; P = 0.010) during the incremental test, but did not increase average power output selected during exercise at RPE 9 (P = 0.235) or 13 (P = 0.992). Subjects were unable to perceive the difference in FIO2 at any stage (P0.14).Small increases in inspired oxygen concentration at moderate altitude are imperceptible and do not appear to influence selection of submaximal work rates at RPE ≤ 13.

We aimed to assess detailed ventilatory and sensory responses to exercise contrasting subjects with and without PAH. 20 non-smoking patients with PAH (37.5 ± 12.1 ys; FEV1/FVC = 0.77 ± 0.04; mPAP by heart catheterization = 50.6 ± 18.1 mmHg) and 10 matched controls performed cycling cardiopulmonary exercise test with serial assessments of dyspnea, airway occlusion pressure during the first 0.1 s (P0.1) of tidal volume and inspiratory capacity (IC). Patients showed lower spirometric variables compared to controls. Dyspnea and ventilation (VE) were significantly higher in patients for a given work rate. Dyspnea persisted more intense in patients even when expressed as a function of VE. Lower IC at rest (in non-hyperinflators; n = 10) or exercise-induced reduction in IC (in hyperinflators) predisposed patients to achieve earlier and at lower workloads a critical inspiratory reserve volume (IRV). At this point, there was a sudden rise in P0.1 and dyspnea perception. Attainment of a critical IRV at premature workloads leads to neuromechanical dissociation with an abrupt increment in exertional dyspnea.

Introduction/Aim Exercise training in pulmonary rehabilitation is an effective intervention for people with interstitial lung disease (ILD). However, a large proportion of those who participate are not attaining its benefit. Alternative training strategies to the current method of continuous exercise at moderate intensity may prove more effective in people with ILD. This study aims to compare the acute physiological effects of high intensity interval training (HIIT), moderate intensity interval training (MIIT) and moderate intensity continuous training (MICT) in people with ILD. Methods Six participants with ILD performed in random order three different cycle training protocols until volitional exhaustion, symptom limitation or desaturation (SpO2 < 80%) after performance of a baseline cardiopulmonary exercise test. Training protocols were thirty second intervals alternating 100% peak work rate with unloaded cycling (HIIT), two minute intervals alternating between 80% and 40% peak work rate (MIIT) and continuous exercise at 60% peak work rate (MICT). The cycle tests were separated by a minimum of one week. Heart rate (HR), blood pressure, SpO2, oxygen uptake (VO2), minute ventilation (VE) and Borg scores for dyspnoea and fatigue were recorded. Results The MIIT protocol resulted in significantly higher VO2, HR and VE (Table 1) when compared to other exercise protocols. During MIIT, participants exercised at a higher percentage of VO2peak (Table 1) and were associated with more dyspnoea, leg fatigue and oxygen desaturation, although this was not statistically significant. There was no significant difference between HIIT and MICT protocols for the VO2, VE, HR, SpO2, leg fatigue or dyspnoea. However, HIIT was associated with a smaller volume of work. Conclusion Using HIIT for people with ILD may allow for a greater training load with similar levels of breathlessness and desaturation to traditional endurance training. Whereas MIIT appears to result in a greater physiological challenge suggesting it is a less effective training strategy.

Background/aim The purpose of this study was to investigate possible effects of anti-TNF alpha therapy on cardiorespiratory fitness and physical functional capacity of patients with ankylosing spondylitis (AS). Materials and methods Twenty-eight AS patients meeting the modified New York criteria with active disease state and an equivalent number of healthy individuals as the control were prospectively enrolled. Physical working capacity and aerobic exercise capacity of the participants were determined by using cardiopulmonary exercise tests, performed before and 4 months after initiation of anti-TNF alpha therapy. Results The mean age of the patients was 37 ± 9.1 years, and mean duration of disease was 8.9 ± 7.6 years. Patients with AS exhibited significantly lower aerobic exercise capacity (VO2peak: 21.2 ± 5.5 vs. 27.2 ± 6.6 ml/kg/min, P = 0.001), maximum power output (110.4 ± 34.8 vs.153 ± 39.8 W, P = 0.0001), and exercise duration (16.3 ± 2.6 vs. 19.6 ± 2.9 min, P = 0.0001) than the healthy controls. When patients were reevaluated after 4 months of anti-TNF alpha therapy, significant improvement was obtained in patients’ aerobic capacity, maximum power output, and exercise duration. Conclusions Results from this study indicate that in addition to inflammatory parameters and quality of life index, even short-term anti-TNF alpha therapy results in significant improvement in cardiopulmonary health status as objectively reflected by peak VO2,maximum work rate, and exercise duration.