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Many birds and mammals show substantial circadian variation in body temperature, which has been attributed to fluctuations in ambient temperature and energy reserves. However, to fully understand the variation in body temperature over the course of the day, we also need to consider effects of variation in work rate. We made use of a dataset on body temperature during the resting and active periods in female marsh tits (Poecile palustris) that bred in a temperate area and were subjected to experimental changes in reproductive investment through brood size manipulations. Furthermore, the amplitude increased with daytime, but were unaffected by nighttime, ambient temperature. Amplitudes in females with manipulated broods were 44% above predictions based on inter-specific allometric relationships. In extreme cases, amplitudes were > 100% above predicted values. However, no individual female realised the maximum potential amplitude (8.5 °C, i.e. the difference between the highest and lowest body temperature within the population) but seemed to prioritise either a reduction in body temperature at night or an increase in body temperature in the day. This suggests that body temperature amplitude might be constrained by costs that preclude extensive use of both low nighttime and high daytime body temperatures within the same individual. Amplitudes in the range found here (0.5–6.7 °C) have previously mostly been reported from sub-tropical and/or arid habitats. We show that comparable values can also be found amongst birds in relatively cool, temperate regions, partly due to a pronounced increase in body temperature during periods with high work rate.

[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%.

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.

AmaçMeme kanserindenkurtulan hastalarda uzun dönemtedavi yan etkileri yaşam kalitesi üzerinde olumsuzetkilere yol açmaktadır. Egzersizin, bu hastaların fizikselve psikolojik durumları üzerindeki olumlu etkisibilinmektedir. Bu çalışmada, meme kanseri tanısıylaradyoterapi alan hastalarda tedavi sırasında egzersizinfiziksel ve psikolojik duruma etkisini araştırmayıamaçladık.Gereç ve YöntemÇalışma, randomize kontrollü olarak rehabilitasyonpolikliniğinde yapıldı. Adjuvan radyoterapi için sevkedilen histolojik olarak kanıtlanmış evre I - III memekanseri hastaları, denetimli bir aerobik ve güçlendirmeegzersiz programı veya egzersiz eğitimi olmaksızınstandart tıbbi bakım olmak üzere iki gruba randomizeedildi. Birincil sonuç parametreleri RosenbergBenlik Saygısı Ölçeği (RSES), Kısa Form-36 (SF_36)Yaşam Kalitesi, Başa Çıkma Stratejileri Anketi (COPEEnvanteri), Yorgunluk Şiddeti Ölçeği (FSS), BeckDepresyon Envanteri (BDI), Beck Anksiyete Envanteri( BAI) olarak belirlendi. Bu parametreler 6 haftalık egzersizantrenmanından 1 hafta önce ve 1 hafta sonradeğerlendirildi.BulgularTekrarlanan ölçüm analizinde egzersiz grubunda BAIve FSS skorları azalmış, genel sağlık (GH) ve enerji/yorgunluk (E) skorları egzersiz grubunda artmış(p=0.045, Cohen d=0.757 BAI için, p= 0.02, Cohend=0.863, p=0.010, Cohen d =1.02 GH için, p=0.032,Cohen d=0.801 E için) olarak bulundu. Kontrol grubundaprobleme dayalı başa çıkma puanının iseazaldığı saptandı (p=0.049, Cohen d=0.641). BDI veRSES puanlarında anlamlı fark bulunmadı (p>0.05).SonuçSonuç olarak, adjuvan radyoterapi sırasında denetimliegzersiz eğitiminin anksiyete, yorgunluk, enerji, genelsağlık algılarını iyileştirdiği ve etkili baş etme stratejilerininkullanılmasında azalmayı önlediği görüldü., ObjectiveTreatment side effects lead to a negative impact onthe quality of life in breast cancer survivors. Exerciseis reported to improve the physical and psychologicalstatus of these patients. We aimed to investigate theeffect of exercise during radiotherapy on physical andpsychological status in breast cancer patients.Material and MethodA randomized controlled study was set in outpatientrehabilitation clinic. Histologically proven stageI-III breast cancer patients referred for adjuvantradiotherapy were randomly assigned to a supervisedaerobic and strengthening exercise program or usualmedical care without exercise training. The primaryoutcome parameters were Rosenberg Self EsteemScale (RSES), Short Form-36 (SF_36) Quality of life,Coping Strategies Questionnaire (COPE Inventory),Fatigue Severity Scale (FSS), Beck DepressionInventory (BDI), Beck Anxiety Inventory (BAI). Endpoints were assessed 1 week prior to and 1 weekfollowing 6 weeks of exercise training.ResultsIn the repeated measured analysis, BAI and FSSscores decreased, general health (GH) and energy/fatigue (E) scores of SF-36 increased in the exercisegroup (p=0.045, Cohen d=0.757 for BAI, p=0.02,Cohen d=0.863, p=0.010, Cohen d =1.02 for GH,p=0.032, Cohen d=0.801 for E), while the use ofproblem-based coping score decreased in the controlgroup (p=0.049, Cohen d=0.641). No significantdifferences were found in scores for BDI and RSES(p>0.05).ConclusionIn conclusion, supervised comined exercise trainingduring adjuvant radiotherapy improved anxiety,fatigue, energy, general health perceptions andprevented decreasing in using effective copingstrategies.

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 purpose of this study was to evaluate upper-limb cooling following (treadmill) exercise performed in the heat (33oC, 70% relative humidity) at each of three speeds: light (6 km.h-1), intermediate (8 km.h-1) and moderate intensity (10 km.h-1). In all trials, exercise ceased when rectal temperature reached 39.0oC. Participants adopted a sitting position for a 20-min recovery, and liquid-cooling sleeves with cold water (6.3oC) were immediately positioned. The chosen work rates resulted in a two-fold difference in exercise duration across those trials, which terminated without significant between-trial differences within either auditory canal or rectal temperatures. Auditory canal temperature elevation rates became progressively faster as the work rate increased: 0.03oC.min-1 (light), 0.05oC.min-1 (intermediate) and 0.07oC.min-1 (moderate) (p0.05). That outcome was reflected in auditory canal cooling rates (0.03oC.min-1 [light], 0.04oC.min-1 [intermediate] and 0.05oC.min-1 [moderate]). Nevertheless, rectal temperatures continued to rise throughout recovery. It is concluded that heat extraction from moderately hyperthermic individuals, using upper-limb cooling sleeves, appears to be equally rapid, regardless of heating speed, providing the same level of hyperthermia was attained prior to initiating treatment.

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’.

Background: Despite the importance of using a thorough understanding of competition demands to optimize preparatory strategies, there is a paucity of longitudinal workload data in ice hockey. Objectives: The purpose of this study was to determine differences in workload characteristics between training and matches, and assess differences between forwards and defensemen. Methods: All players from a NCAA Division I Men’s Ice Hockey Team wore Catapult S5 units for all on-ice activities for two consecutive seasons. Seven workload variables (Player Load, Skating Load, Explosive Efforts, High Skate Load, Player Load·min-1, Skating Load·min-1, and Average Stride Force·lb-1) were used to quantify training and match workload characteristics. Results: Compared to training, matches resulted in significantly higher Player Load (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.

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.

Objectives: During an incremental exercise test, increased metabolic demands of exercising muscle should be compensated with increased O2 uptake and heart rate until to their maximal levels. Anaerobic threshold (AT) describes the point of metabolic transition from aerobic to anaerobic metabolism and reflect moderate exercise intensity. The aim of this study was to evaluate O2 uptake to heart beat ratio (O2 pulse) and heat rate to work rate ratio (HR/WR) in response to constant load exercise at work load corresponded to AT. Method: Twelve healthy young male subjects initially performed an incremental exercise test (15 W/min) until exhaustion. Then, each subject performed a 30 min of constant load exercise test that work load at their AT on separate days. Pulmonary gas exchange parameters were measured breath-by breath using a metabolic gas analyser. Cardiac parameters were followed continuously beat-by beat using a 12 lead ECG. AT estimated non-invasively using V-slope method. Results: The heart rate for each watt of work production (HR/WR) was ranged between 0.97 beat/min/W to 1.76 beat/min/W and averaged 1.25±0.2 beat/min/W. The O2 pulse was ranged between 10.56 mL/min/beat to 16.15 mL/min/beat and averaged 13.38±1.5 mL/min/beat at the end of the test. A negative statistically significant correlation (R = - 0.90316, p

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.

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.

Aims The kinetics of recovery‐period oxygen uptake (VO2) are affected by the O2 deficit generated during exercise. However, studies using ramp tests (RTs) and constant work rate tests (CT) have differently characterized VO2 responses to increased exercise intensity differently. We used these two types of loading patterns to investigate the effects of low‐intensity, medium‐intensity, and high‐intensity exercises on the half time (T1/2) of recovery‐period VO2 and the mechanism. Methods and results Ten healthy men aged 21.2 ± 0.9 years underwent symptom‐limited cardiopulmonary exercise tests with the ramp protocol to determine their anaerobic threshold. All subjects subsequently underwent three submaximal RT and CT at low, moderate, and high intensities. In all RTs, subjects began exercise by warming up (20 W). In CT, T1/2 was significantly lengthened as exercise intensity increased (CT‐low: 34.0 ± 3.9 s, CT‐moderate: 39.5 ± 3.5 s, CT‐high:44.6 ± 4.2 s; P

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

BackgroundExercise training provides benefits for individuals with cystic fibrosis; however, the optimal program is unclear. High-intensity interval training is safe and effective for improving ‘functional capacity’ in these individuals with peak rate of O2uptake typically referenced. The ability to adjust submaximal rate of oxygen uptake (V̇O2kinetics) might be more important for everyday function because maximal efforts are usually not undertaken. Moreover, the ability of high-intensity training to accelerate V̇O2kinetics for individuals with cystic fibrosis could be enhanced with O2supplementation during training.MethodsNine individuals with cystic fibrosis completed incremental cycling to limit of tolerance followed by 8 weeks of high-intensity interval cycling (2 sessions per week x ~ 45 min per session) either with (n = 5; O2+) or without (AMB) oxygen supplementation (100%). Each session involved work intervals at 70% of peak work rate followed by 60 s of recovery at 35%. For progression, duration of work intervals was increased according to participant tolerance.ResultsBoth groups experienced a significant increase in work-interval duration over the course of the intervention (O2+, 1736 ± 141v. 700 ± 154 s; AMB, 1463 ± 598v. 953 ± 253 s;P = 0.000); however, the increase experienced by O2+ was greater (P = 0.027). During low-intensity constant-work-rate cycling, the V̇O2mean response time was shortened post compared to pre training (O2+, 34 ± 11v. 44 ± 9 s; AMB, 39 ± 14v. 45 ± 17 s;P = 0.000) while during high-intensity constant-work-rate cycling, time to exhaustion was increased (O2+, 1628 ± 163v. 705 ± 133 s; AMB, 1073 ± 633v. 690 ± 348 s;P = 0.002) and blood [lactate] response was decreased (O2+, 4.5 ± 0.9v. 6.3 ± 1.4 mmol.L− 1; AMB, 4.5 ± 0.6v. 5.2 ± 1.4 mmol.L− 1;P = 0.003). These positive adaptations were similar regardless of gas inspiration during training.ConclusionEight weeks of high-intensity interval training for patients with cystic fibrosis accelerated V̇O2kinetics and increased time to exhaustion. This provides some evidence that these patients may benefit from this type of exercise.Trial registrationThis study was retrospectively registered in the ISRTCN registry on 22/06/2019 (#ISRCTN13864650).

Purpose To investigate the gross efficiency (GE) and delta efficiency (DE) during cycling and running in elite triathletes. Methods Five male and five female elite triathletes completed two incremental treadmill tests with an inclination of 2.5° to determine their GE and DE during cycling and running. The speed increments between the 5-min stages were 2.4 and 0.6 km h−1 during the cycling and running tests, respectively. For each test, GE was calculated as the ratio between the mechanical work rate (MWR) and the metabolic rate (MR) at an intensity corresponding to a net increase in blood-lactate concentration of 1 mmol l−1. DE was calculated by dividing the delta increase in MWR by the delta increase in MR for each test. Pearson correlations and paired-sample t tests were used to investigate the relationships and differences, respectively. Results There was a correlation between GEcycle and GErun (r = 0.66; P = 0.038; R2 = 0.44), but the correlation between DEcycle and DErun was not statistically significant (r = − 0.045; P = 0.90; R2 = 0.0020). There were differences between GEcycle and GErun (t = 80.8; P cycle and DErun (t = 27.8; P Conclusions Elite triathletes with high GE during running also have high GE during cycling, when exercising at a treadmill inclination of 2.5°. For a moderate uphill incline, elite triathletes are more energy efficient during cycling than during running, independent of work rate.

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.

Purpose. this study aimed to investigate the influence of the outfield goalkeeper game situation on the running performance of teammates and opponent players during professional futsal matches. Methods. the movement trajectories of 126 professional players during 6 official matches were analysed with a video-based tracking system (30 Hz). Distance covered and percentage of distance covered in different speed ranges were calculated to identify differences per team and per sub-phase of the game (traditional vs. outfield goalkeeper situation). Results. the teammates of the outfield goalkeeper spent a higher percentage of the distance covered in the standing and walking speed range (36.27 ± 15.38%) compared with the teammates of the traditional goalkeeper (31.44 ± 7.74%). the outfield goalkeeper spent a smaller percentage of the distance covered in the standing and walking range (41.13 ± 10.86% vs. 80.77 ± 4.30%) and a higher percentage in the low- and medium-intensity running range (31.59 ± 5.59% vs. 15.07 ± 2.74% and 14.33 ± 3.90% vs. 2.50 ± 1.19%, respectively), as well as covered a greater distance (77.41 ± 16.00 m/min) than the traditional goalkeeper (33.81 ± 3.66 m/min). Conclusions. these findings provide coaches with a background concerning the requirements during the outfield goalkeeper situation as guidelines for final exercises in training sessions.

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.

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.

Objective: To evaluate the criterion validity and responsiveness of the steep ramp test (SRT) compared with the cardiopulmonary exercise test (CPET) in evaluating aerobic capacity in survivors of cancer participating in a rehabilitation program.Design: A prospective cohort study in which survivors of cancer performed an SRT and CPET before (T=0) and after (T=1) a 10-week exercise rehabilitation program. Peak work rate achieved during the SRT (SRT-WRpeak) was compared with peak oxygen consumption measured during the CPET (CPET-VO(2)peak), which is the criterion standard for aerobic capacity. Correlation coefficients were calculated between SRT-WRpeak and CPET-VO(2)peak at T=0 to examine criterion validity and between changes in SRT-WRpeak and CPET-VO(2)peak from T=0 to T=1 to determine responsiveness. Receiver operating characteristic analysis was performed to examine the ability of the SRT to detect a true improvement (6%) in CPET-VO(2)peak.Setting: University medical center.Participants: Survivors of cancer (N=106).Interventions: Exercise rehabilitation.Main Outcome Measures: Correlation coefficients between CPET-VO2peak and SRT-WRpeak and between changes in CPET-VO2peak and SRTWRpeak.Results: An r of 0.86 (N=106) was found for the relation between SRT-WRpeak and CPET-VO(2)peak at T=0. An r of 0.51 was observed for the relation between changes in SRT-WRpeak and CPET-VO(2)peak (n=59). Receiver operating characteristic analysis showed an area under the curve of 0.74 for the SRT to detect a true improvement in CPET-VO(2)peak, with an optimal cutoff value of +0.26 W/kg (sensitivity 70.7%, specificity 66.7%).Conclusions: Because SRT-WRpeak and CPET-VO(2)peak were strongly correlated, the SRT seems a valid tool to estimate aerobic capacity in survivors of cancer. The responsiveness to measure changes in aerobic capacity appears moderate. Nevertheless, the SRT seems able to detect improvement in aerobic capacity, with a cutoff value of 0.26 W/kg. (C) 2021 The Authors. Published by Elsevier Inc. on behalf of The American Congress of Rehabilitation Medicine.

In high-intensity interval training the interval duration can be adjusted to optimize training results in oxygen uptake, cardiac output, and local oxygen supply. This study aimed to compare these variables in two interval trainings (long intervals HIIT3m: 3 min work, 3 min active rest vs. short intervals HIIT30s: 30 s work, 30 s active rest) at the same overall work rate and training duration. 24 participants accomplished both protocols, (work: 80% power output at VO2peak, relief: 85% power output at gas exchange threshold) in randomized order. Spirometry, impedance cardiography, and near-infrared spectroscopy were used to analyze the physiological stress of the cardiopulmonary system and muscle tissue. Although times above gas exchange threshold were shorter in HIIT3m (HIIT3m 1669.9 ± 310.9 s vs. HIIT30s 1769.5 ± 189.0 s, p = 0.034), both protocols evoked similar average fractional utilization of VO2peak (HIIT3m 65.23 ± 4.68% VO2peak vs. HIIT30s 64.39 ± 6.78% VO2peak, p = 0.261). However, HIIT3m resulted in higher cardiovascular responses during the loaded phases (VO2p &lt, 0.001, cardiac output p &lt, 0.001). Local hemodynamics were not different between both protocols. Average physiological responses were not different in both protocols owning to incomplete rests in HIIT30s and large response amplitudes in HIIT3m. Despite lower acute cardiovascular stress in HIIT30s, short submaximal intervals may also trigger microvascular and metabolic adaptions similar to HIIT3m. Therefore, the adaption of interval duration is an important tool to adjust the goals of interval training to the needs of the athlete or patient.

Background. Mechanical efficiency (ME) might be an important parameter evaluating cardiometabolic health and the effectiveness of physical activity interventions in individuals with obesity. However, whether these cardiometabolic risk factors may relate to ME in adolescents with obesity is not known yet. Therefore, this study aims to compare the mechanical efficiency during maximal exercise testing between adolescents with obesity and lean adolescents, and to examine associations with exercise tolerance and metabolic health. Methods. Twenty-nine adolescents with obesity (BMI SDS: 2.11 ± 0.32, age: 13.4 ± 1.1 years, male/female: 15/14) and 29 lean (BMI SDS: −0.16 ± 0.84, age: 14.0 ± 1.5 years, male/female: 16/13) adolescents performed a maximal cardiopulmonary exercise test from which the net mechanical efficiency (MEnet) and substrate oxidation (carbohydrates and lipids) were calculated. Indicators for peak performance were collected. Biochemistry (lipid profile, glycaemic control, inflammation, leptin) was studied in fasted blood samples. Regression analyses were applied to examine relations between MEnet and exercise tolerance or blood variables in the total group. Results. Peak work rate (WRpeak), oxygen uptake (V˙O2peak)/WRpeak, ME, and MEnet were significantly lower (p &lt, 0.05) in adolescents with obesity compared to their lean counterparts (p &lt, 0.05). Furthermore, a reduced MEnet was independently related to a lower WRpeak (SC β = 2.447, p &lt, 0.001) and elevated carbohydrate oxidation during exercise (SC β = −0.497, 0.001), as well as to elevated blood low-density lipoprotein cholesterol (SC β = −0.275, p = 0.034) and fasting glucose (SC β = −0.256, p = 0.049) concentration. Conclusion. In adolescents with obesity, the mechanical efficiency is lowered during exercise and this relates to exercise intolerance and a worse metabolic health.

Running economy (RE) at a given submaximal running velocity is defined as oxygen consumption per minute per kg body mass. We investigated RE in a group of 12 male elite runners of national class. In addition to RE at 14 and 18 km h−1 we measured the maximal oxygen consumption (VO2max) and anthropometric measures including the moment arm of the Achilles tendon (L Ach), shank and foot volumes, and muscular fascicle lengths. A 3‐D biomechanical movement analysis of treadmill running was also conducted. RE was on average 47.8 and 62.3 ml O2 min−1 kg−1 at 14 and 18 km h−1. Maximal difference between the individual athletes was 21% at 18 km h−1. Mechanical work rate was significantly correlated with VO2 measured in L min−1 at both running velocities. However, RE and relative work rate were not significantly correlated. L Ach was significantly correlated with RE at 18 km h−1 implying that a short moment arm is advantageous regarding RE. Neither foot volume nor shank volume were significantly correlated to RE. Relative muscle fascicle length of m. soleus was significantly correlated with RE at 18 km h−1. Whole body stiffness and leg stiffness were significantly correlated with L Ach indicating that a short moment arm coincided with high stiffness. It is concluded that a short L Ach is correlated with RE. Probably, a short L Ach allows for storage of a larger amount of elastic energy in the tendon and influences the force–velocity relation toward a lower contraction velocity., Running economy was found to be significantly related to Achilles tendon moment arm, foot length ratio, whole body stiffness and leg stiffness, and muscular fascicle length.

Maximal oxygen uptake (VO2max) declines with advancing age and is a predictor of morbidity and mortality risk. The purpose here was to assess the utility of constant load tests performed either above or below peak work rate obtained from a graded exercise test for verification of VO2max in older adults. Twenty‐two healthy older adults (9M, 13F, 67 ± 6 years, BMI: 26.3 ± 5.1 kg·m−2) participated in the study. Participants were asked to complete two experimental trials in a randomized, counterbalanced cross‐over design. Both trials (cycle ergometer) consisted of (1) an identical graded exercise test (ramp) and (2) a constant load test at either 85% (CL85; n = 22) or 110% (CL110; n = 20) of the peak work rate achieved during the associated ramp (performed 10‐min post ramp). No significant differences were observed for peak VO2 (L·min−1) between CL85 (1.86 ± 0.72; p = 0.679) or CL110 (1.79 ± 0.73; p = 0.200) and the associated ramp (Ramp85, 1.85 ± 0.73; Ramp110, 1.85 ± 0.57). Using the study participant's mean coefficient of variation in peak VO2 between the two identical ramp tests (2.9%) to compare individual differences between constant load tests and the associated ramp revealed 19/22 (86%) of participants achieved a peak VO2 during CL85 that was similar or higher versus the ramp, while only 13/20 (65%) of participants achieved a peak VO2 during CL110 that was similar or higher versus the ramp. These data indicate that if a verification of VO2max is warranted when testing older adults, a constant load effort at 85% of ramp peak power may be more likely to verify VO2max as compared to an effort at 110% of ramp peak power., The intensity at which a constant load test can be used following a graded exercise test to verify maximal values in healthy older adults was examined. When verification of maximal values is warranted, our findings indicate that a constant load test performed at 85% of ramp peak power is more likely to verify a maximal effort and VO2max in healthy older adults as compared to a constant load effort at 110% of ramp peak power.