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Purpose: The present study examined the effects of sustained, isometric low- versus high-intensity tasks on time to task failure (TTF), performance fatigability (PF), ratings of perceived exertion (RPE), and the perceived causes of task termination from a post-test questionnaire (PTQ)., Methods: Ten men (mean ± SD: age = 21.1 ± 2.3 years; height = 180.2 ± 5.7 cm; body mass = 79.5 ± 8.8 kg) performed maximal voluntary isometric contractions (MVICs) before and after fatiguing, isometric forearm flexion tasks anchored to the torque corresponding to RPE values of 2 (TRQ2FT = 23.8 ± 7.1 N·m) and 8 (TRQ8FT = 60.9 ± 11.4 N·m). In addition, the subjects completed a PTQ which surveyed whether the perceived sensations of fatigue or pain, and/or the psychological factors of loss of focus and motivation contributed to the decision to terminate the task. Repeated measures ANOVAs, Wilcoxon-Signed Rank tests, and Spearman's Rank-Order Correlations were used to analyze the data., Results: Across the fatiguing tasks, there were similar decreases in MVIC torque (95.2 ± 20.3 vs. 68.9 ± 15.6 N·m; p < 0.001) and RPE values (p = 0.122) at task failure for TRQ2FT (7.4 ± 2.7) and TRQ8FT (8.9 ± 1.0), but a longer (p = 0.005) TTF for the TRQ2FT (245.0 ± 177.0 s) than TRQ8FT (36.8 ± 11.1 s)., Conclusions: Despite reaching task failure, the subjects were able to perform MVICs that were 100-300% greater than the target torque values within seconds of terminating the tasks. Thus, we hypothesized that task failure was not caused by an inability to produce sufficient torque to sustain the tasks, but rather an unwillingness to continue the task., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Adolescents with functional neurological symptoms disorder (FNSD) commonly present walking abnormalities. Walking is influenced by 'objective' (e.g., fitness) and 'subjective' (e.g., fear) components. Rate of perceived exertion (RPE) reflects the interaction between these two components. This study compared the walking ability and RPE before and after rehabilitation of adolescents with FNSD to adolescents with moderate-to-severe traumatic brain injury (TBI). Factors predicting walking and RPE were also examined., Methods: Adolescents with FNSD ( n = 31) and adolescents with moderate-to-severe TBI ( n = 28) aged 6 to 18 years participated in the study. Participants received a multidisciplinary rehabilitation program. Six-minute walk test (6MWT) and RPE were assessed before and after rehabilitation., Results: At pre-test, the TBI group presented lower RPE than the FNSD group (3.38 ± 2.49 and 6.25 ± 2.71, respectively). In the FNSD group, pre-test 6MWT was a significant predictor of post-test 6MWT (adjusted R 2 = 0.17; p = 0.01). In the TBI group, post-test 6MWT was significantly predicted by both the pre-test 6MWT and age (adjusted R 2 = 0.16; p = 0.04)., Conclusions: Prior to the intervention, adolescents with FNSD perceived walking as a more difficult activity than adolescents with TBI. Post-intervention, although the intervention was effective in terms of changes in 6MWT and RPE, the 'subjective' component still contributed to the elevated RPE of the FNSD group.

Experiences of physical exertion guide our assessments of effort. While these assessments critically influence our decisions to engage in daily activities, little is known about how they are generated. We had female and male human participants exert grip force and assess how effortful these exertions felt; and used magnetic resonance spectroscopy to measure their brain GABA concentration. We found that variability in exertion (i.e., the coefficient of variation in their force exertion profile) was associated with increases in assessments of effort, making participants judge efforts as more costly. GABA levels in the sensorimotor cortex (SM1) moderated the influence of exertion variability on overassessments of effort. In individuals with higher sensorimotor GABA, exertion variability had a diminished influence on overassessments of effort. Essentially, sensorimotor GABA had a protective effect on the influence of exertion variability on inflations of effort assessment. Our findings provide a neurobiological account of how the brain's GABAergic system integrates features of physical exertion into judgments of effort, and how basic sensorimotor properties may influence higher-order judgments of effort. SIGNIFICANCE STATEMENT Feelings of effort critically shape our decisions to partake in activities of daily living. It remains unclear how the brain translates physical activity into judgments about effort (i.e., "How effortful did that activity feel?"). Using modeling of behavior and neuroimaging, we show how the nervous system uses information about physical exertion to generate assessments of effort. We found that higher variability in exertion was associated with increases in assessments of effort, making participants judge efforts as more costly. GABA, the brain's main inhibitory neurotransmitter, moderated the influence of exertion variability on overassessments of effort. These findings illustrate how low-level features of motor performance and sensorimotor neurochemistry influence higher-order cognitive processes related to feelings of effort., (Copyright © 2022 the authors.)

Research suggests that people's perceptions of the typical physical activity behaviors of others-descriptive norms-shape their own physical activity. However, prior work has primarily used cross-sectional designs, focused on people's physical activity intentions or self-reported overall physical activity, and failed to attend to how the normative referent affects the norm-behavior relationship. In a pre-registered experiment, we manipulated the descriptive norm to explore its effect on perceived exertion during, and objectively assessed performance on, an exercise (running) task. We also measured the strength of participants' social identification as a member of the norm reference group as a potential moderator. Following a baseline trial, participants (N = 78) were either told that their baseline score on the running task was below average (high norm condition) or above average (low norm condition) compared to members of the reference group. Participants in both conditions tended to perform better in Trial 2 than Trial 1. However, participants in the high norm condition improved their performance significantly (2.5 times) more than participants in the low norm condition. Social identification moderated the effect of the norm manipulation on perceived exertion. High identifiers tended to exert themselves less than low identifiers during Trial 2 if they were told they were above average, whereas if told they were below average, high identifiers exerted themselves slightly more than low identifiers. Results provide evidence that descriptive norm messages can improve people's performance on physically demanding tasks, and indicate that descriptive physical activity norms may be more influential when the norm reference group is subjectively meaningful. Opportunities to fruitfully deploy norm messages in applied contexts are discussed., (© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Exertion may alter running mechanics and increase injury risk. Effects of exertion following gait-retraining are unknown., Objectives: To determine how exertion effects load rates, footstrike, and cadence in runners following a transition to forefoot strike (FFS) or increased cadence (CAD) gait-retraining., Methods: 33 (9 M, 24 F) healthy rearfoot strike runners were randomized into CAD or FFS groups. All runners received strengthening exercises and gait-retraining. 3D kinetic and kinematic motion analysis with instrumented treadmill at self-selected speed was performed at baseline & 1-week post-intervention, including an exerted run. Exertion was ≥17 on Borg's Rating of Perceived Exertion scale or voluntary termination of running., Results: Within group comparisons between fresh and exerted running: Cadence not affected in either group. Foot angle at contact became less plantarflexed in FFS (-2.2°, ±0.4) and was unchanged in CAD. Both groups increased vertical average load rate (FFS +16.9%, CAD +13.6%). CAD increased vertical stiffness (+8.6 kN/m). FFS reduced ankle excursion (1.8 ° ). (p ≤ 0.05 for all values listed)., Conclusion: Both FFS and CAD exhibited increased load rates with exertion. Variables that may have increased load rates were different for each group. CAD runners had increased vertical stiffness while FFS runners had reduced plantarflexion at contact and reduced ankle dorsiflexion excursion.

Objectives: To identify the symptoms responsible for cessation of exercise testing and evaluate changes in post-concussion symptom scores on the Post-Concussion Symptom Scale (PCSS) from the Sport-Concussion Assessment Tool (SCAT5) immediately, 1-4h, and 6-12h following completion of the Buffalo Concussion Treadmill Test (BCTT) in youth and adults who have sustained a sport-related concussion., Design: Prospective case-series., Methods: Individuals who were diagnosed with a sport-related concussion and self-reported difficulties with exertion were referred to perform an exertional treadmill test. Individuals were recruited from a university sports medicine clinic. Change in PCSS symptom severity scores were operationally defined as a change ≥4 points., Results: Forty-five individuals aged 13-57 years consented to participate. A total of 14/24 (58.3%) female and 13/21 (61.9%) male participants reported an increase in symptom severity scores immediately following the BCTT. At 1-4h, 5/10 (50.0%) males and 5/14 (35.7%) females who completed the PCSS had elevated symptom severity scores compared to pre-exertion. Only 24.2% (3/17 males and 5/16 females) of participants completing the PCSS at 6-12h reported increased symptom severity scores., Conclusion: Exertional testing is an important component of a multifaceted assessment following concussion; however, previous research evaluating symptom responses to exertion is limited. This study provides evidence to suggest individuals who experience an exacerbation of concussion-associated symptoms after exertion are likely to return to pre-exertion levels within the same day. Future research monitoring symptoms following exertion and throughout recovery should be performed in tandem with physiological measures to better understand the source of symptoms., (Copyright © 2020 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

Purpose: The primary purpose of the current study was to determine the usefulness of Buteyko breathing technique (BBT) in reducing dyspnea in patients with one form of Paradoxical Vocal Fold Motion (PVFM), exertion-induced PVFM (EI-PVFM), concomitant with hyperventilation. The secondary purpose was to determine whether BBT had an effect on physiological markers of hyperventilation, as speculated by BBT theory: respiratory tidal minute volume (RTMV), end-tidal carbon dioxide (ETCO 2 ), and resting heart rate (HR)., Methods: Using a within-subjects, repeated measures group design, 12 participants with EI-PVFM and hyperventilation underwent 12 weeks of BBT, following an initial no-treatment control condition. Outcome measures of PVFM-dyspnea frequency and severity-and of hyperventilation-HR, RTMV, and ETCO 2 -were acquired pre- and post-treatment., Results: Results showed post-treatment decreases in dyspnea severity, HR, and RTMV, as well as increases in ETCO 2 . Decreases in dyspnea and RTMV measures remained after correction for alpha inflation., Conclusions: Findings suggest BBT may be useful for some individuals with EI-PVFM and hyperventilation. The high prevalence of hyperventilation in EI-PVFM found in the current study warrants further investigation., (Copyright © 2019 The Voice Foundation. Published by Elsevier Inc. All rights reserved.)

Objective: Lifeguard teams carry out their work in extremely hot conditions in many parts of the world. The aim of this study was to analyze the impact of high temperatures on physiological parameters during cardiopulmonary resuscitation (CPR)., Method: A randomized quasi-experimental cross-over design was used to test physiological lifesaving demands (50 min acclimatization +10 min CPR) in two different thermal environments: Thermo-neutral environment (25 °C) vs Hyperthermic environment (37 °C)., Results: The data obtained from 21 lifeguards were included, this covers a total of 420 min of resuscitation. The CPR performance was constantly maintained during the 10 min. The Oxygen uptake (VO 2) ranged from 17 to 18 ml/min/kg for chest compressions (CC) and between 13 and 14 ml/min/kg for ventilations (V) at both 25 °C and 37 °C, with no significant difference between environments (p > 0.05). The percentage of maximum heart rate (%HR max) increased between 7% and 8% at 37 °C (p < 0.001), ranging between 75% and 82% of HR max. The loss of body fluids (LBF) was higher in the hyperthermic environment; LBF: (37 °C: 400 ± 187 g vs 25 °C: 148 ± 81 g, p < 0.001). Body temperature was 1 °C higher at the end of the test (p < 0.001). The perceived fatigue (RPE) increased by 37° an average of 2 points on a scale of 10 (p = 0.001)., Conclusions: Extreme heat is not a limiting factor in CPR performance with two lifeguards. Metabolic consumption is sustained, with an increase in CC, so V can serve as active rest. Nevertheless, resuscitation at 37 °C results in a higher HR, is more exhausting and causes significant loss of fluids due to sweating., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Referees in sports games have a high level of responsibility as they have to make correct and appropriate decisions at any point during a match. Regarding referees' decision-making (RDM) as a perceptual-cognitive process, evidence suggests that physical load might reduce cognitive performance and thus might reduce RDM performance as well. In consideration of increasing game dynamics, referees have to cope with high physical load, but they have to make correct and appropriate decisions further on. Here, we review the current state of research on the relationship between physical load and RDM. A scoping review was performed, in accordance with the PRISMA guidelines, using the following databases: Scopus, PubMed, Web of Science (all databases), SURF and SPONET (both with an English and German search). Only primary studies written in English or German that investigated the relationship between physical load and RDM in sports games were included. Eleven studies included in the review investigated six physical parameters and RDM: match period, velocity, blood lactate, running time, heart rate, distance covered. Most findings of the studies showed no relationship between physical load and RDM ( n = 18). Thirteen findings suggest a negative relationship and three findings indicate a positive relationship between physical load and RDM. Results of the scoping review show contradictory evidence across and within investigated different physical parameters. As RDM consists of multi-factorial components, it is recommended to conduct systematic research programs - field as well as experimental studies - to resolve the missing control of potential confounding variables and to consider the difference of internal and external load., (© Journal of Sports Science and Medicine.)

Background: There is increasing recognition that heavy exertion can occasionally trigger an acute myocardial infarction (MI), although some uncertainties exist regarding the link. The primary aim of this study was to compare the relative risk (RR) of MI following vigorous exertion between those with confirmed coronary occlusion and those with a non-occluded culprit artery on acute angiography. Secondary aims were to determine if the risk of coronary occlusion is modified by the type of exercise (dynamic or isometric resistance), the frequency of regular exertion or whether the exertion was emotionally charged., Methods: Seven hundred sixty-two (762) participants with MI (410 with coronary occlusion TIMI 0,1), and 352 (46%) with a non-occluded culprit artery (TIMI 2,3) completed a questionnaire within 4days of admission, detailing episodes of physical exertion in the 28hours prior to symptom onset and the usual frequency of such exertion. Exertion exposures within 1hour prior to symptom onset were compared to subjects' usual yearly exposure, with case-crossover methodology., Results: The RR of symptom onset following heavy physical exertion level ≥6 (exertion scale 1-8), was higher in those with TIMI 0,1 compared to those with TIMI 2,3 flow (RR 6.30, 95% CI 4.70-8.50 vs 3.93, 2.89-5.30). The increased risk of coronary occlusion following vigorous exertion was observed following both dynamic exertion and isometric resistance, and did not differ between exertion types. The highest risk of coronary occlusion following exertion was observed in those who were sedentary (regular vigorous exertion <1day weekly) (RR=77, 95% CI 46-132), whereas in those who frequently perform regular vigorous physical exertion (>4days weekly), the RR of symptom onset during exertion was significantly lower, RR 2.3 (95% CI 1.5-3.6). There was no significant difference in relative risk based on whether the exertion was reported as emotionally charged., Conclusions: The relative risk that heavy exertion will trigger a non-fatal MI with an occluded artery is greater than for a non-occluded culprit artery. Both dynamic and isometric exertion increase the relative risk of event, while exposure to regular vigorous exertion reduces the relative risk., (Copyright © 2018 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.)

Fatigue arises during everyday activities, diminishes movement performance, and increases injury risk. Physical (PE) and cognitive exertion (CE) can induce similar feelings of fatigue, but it is not clear whether these also similarly affect movement performance. Therefore, this study examined the influence of PE and CE on anticipatory postural adjustments (APAs) of trunk muscles, which are feedforward mechanisms that contribute to motor control and controlled movement. Rapid arm movement tasks (RAM) were used to induce APAs of the trunk muscles prior and following three experimental conditions in 20 healthy adults: seated rest without exertion (NE), a combined isometric modified Biering-Sörensen and static abdominal curl to induce PE, and a modified incongruent Stroop colour-word task to induce CE. Fatigue was assessed using self-reported measures, and APA onset latencies of the trunk muscles with surface electromyography. Statistical analyses revealed that neither PE nor CE influence APAs of the trunk. Therefore, it is hypothesized that the influence of fatigue on movement performance might not be through altered motor control, but rather by reduced motivation. However, the possibility that fatigue might influence other mechanisms which contribute to trunk motor control, such as APA amplitude and variability, cannot be excluded and need further examination.

Background: Rhabdomyolysis is a syndrome characterized by muscle necrosis that leads to release of the intracellular contents of muscle cells into the systemic circulation. Rhabdomyolysis due to overexertion is an uncommon but well-known severe complication of strenuous activity. Exertional rhabdomyolysis (ER) is typically described in weight lifters and military recruits undergoing basic training. Few cases have been reported in football players without known predisposing risk factors. We report our experience with this condition in college football players in a single institution., Materials and Methods: College football players hospitalized for heat illness complicated by rhabdomyolysis were identified over a 23-year period. Clinical and laboratory findings were collected. Clinical course was recorded., Results: Twelve patients were identified. All were Black males. One had sickle cell trait. BMI averaged 33 kg/m 2 (range 23-45 kg/m 2 ). Peak creatine phosphokinase (CPK) averaged 14,850 IU/L (range 1,021-109,616 IU/L). Serum creatinine averaged 1.9 mg/dl (range 1.2-3.1 mg/dl). Ten of twelve cases occurred in August. All responded to intravenous hydration with normalization of CPK and renal function. All returned to football., Conclusions: ER is a serious complication of strenuous physical activity that can threaten renal function. ER tends to occur in August, which coincides with the start of football practice when athletes are more likely to be detrained. The condition can occur in Black athletes in the absence of sickle cell trait. ER carries a good prognosis when recognized early and treated adequately.

Introduction: It has been suggested that disparities in effort and discomfort between high- and low-load resistance training might exist, which in turn have produced unequivocal adaptations between studies., Methods: Strength responses to heavier load (HL; 80% maximum voluntary isometric torque; MVIT) and lighter load (LL; 50% MVIT) resistance training were examined in addition to acute perceptions of effort and discomfort. Seven men (20.6 ± 0.5 years, 178.9 ± 3.2 cm, 77.1 ± 2.7 kg) performed unilateral resistance training of the knee extensors to momentary failure using HL and LL., Results: Analyses revealed significant pre- to post-intervention increases in strength for both HL and LL, with no significant between-group differences (P > 0.05). Mean repetitions per set, total training time, and discomfort were all significantly higher for LL compared with HL (P < 0.05)., Conclusion: This study indicates that resistance training with HL and LL produces similar strength adaptations, but discomfort should be considered before selecting a training load. Muscle Nerve 56: 797-803, 2017., (© 2016 Wiley Periodicals, Inc.)

The objective of this study was to determine the validity and reliability of the EPInfant pediatric perceived exertion rating scale among Chilean children. Children aged 8-12 years old were selected; their heart rate, perceived exertion and workload were recorded during two consecutive Chester tests performed with a one week interval. Pearson's r coefficient and the intraclass correlation coefficient were estimated. Thirty-one children (17 boys) were included in the study. A strong correlation was observed between perceived exertion and reference criteria, in addition to a high intraclass correlation coefficient. The average difference between the perceived exertion in each test was 1.4 (95% CI: -1.4 to 4.1) and 0.2 (95% CI: -1.8 to 2.2) for boys and girls, respectively. The EPInfant scale showed an acceptable criterion validity and interobserver reliability among children during an incremental step test., (Sociedad Argentina de Pediatría.)

A higher energy cost of walking (Cw) is sometimes observed in MS, and could contribute to fatigue. The purpose of this study was to compare Cw at three speeds in MS and controls, and determine the effects of walking speed on fatigue and perceived exertion. We hypothesized that MS would have higher Cw, fatigue and exertion during walking than controls. Ten persons with MS and 14 controls of similar age and physical activity levels were studied. Oxygen consumption (VO2) was obtained at rest and during treadmill walking at 0.6 and 1.4ms(-1), and preferred speed. Cw was calculated as net VO2:velocity. Fatigue and exertion were assessed using the visual analog fatigue and modified Borg scales, respectively. Preferred treadmill speed was not different between groups. Cw was higher in MS than controls across walking speeds (p=0.003), with a group-by-speed interaction indicating higher Cw in MS at 0.6ms(-1) (p=0.001), but not at preferred speed or 1.4ms(-1). MS reported greater fatigue (p=0.001) and exertion (p=0.004) at all speeds. Despite similar preferred speeds, and Cw at preferred and fast speeds, MS exhibited higher fatigue and exertion at all walking speeds. These results suggest that increased energy demands in MS are most notable at low speeds such as those used in everyday activities, which may contribute to fatigue over the day., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The aim of this paper is to review the evidence for a role for opioids as an intervention for exertion induced breathlessness with regard to exercise tolerance and breathlessness intensity. Current knowledge about exogenous opioids in exertion-induced breathlessness due to disease comes from a variety of phase 2 feasibility or pilot designs with differing duration, doses, drugs, exercise regimes, underlying aetiologies, and outcome measures. They provide interesting data but firm conclusions for either breathlessness severity or exercise endurance cannot be drawn. There are no adequately powered phase 3 trials of opioids which show improved exercise tolerance and/or exertion induced breathlessness. Low dose oral morphine seems well tolerated by most, and is beneficial for breathlessness intensity. Current work to investigate the effect on exercise tolerance is ongoing., (© The Author(s) 2014.)

Ratings of perceived exertion (RPE) were developed to assess exertion during exercise testing. However, assessments of RPE prior to and after exercise have become common and potentially important in understanding exercise behaviour. The purpose of this project was to compare RPE taken before, during and after interval and continuous exercise sessions. Twenty-four participants (12 men, 12 women, body mass index = 24, VO2peak = 41 mL · kg · min(-1)) completed a maximal cycle ergometer test used to prescribe experimental trials: (1) moderate continuous (MC), (2) vigorous continuous (VC), (3) vigorous interval and (4) severe interval. All trials were 20 minutes in length and all intervals utilised 60-second segments and a 1:1 work-to-rest ratio. Predicted exertion was highest in the continuous vigorous trial (p < .05). Exertion increased from beginning to end in all trials (p < .05). Session RPE values were highest for the continuous vigorous trial (p < .05). Findings suggest that interval protocols produce perceptions of effort that are lower than VC exercise but similar to MC exercise. These results help describe the perceptions of effort associated with continuous and interval exercise and suggest that interval exercise can be performed with lower perceived work, which may encourage increased participation.

Background: Morphine is the only opioid which has been clearly demonstrated as effective in the treatment of dyspnea. The role of other opioids has not been sufficiently substantiated., Objective: To evaluate the efficacy of oral transmucosal fentanyl citrate (OTFC) in the treatment of dyspnea on exertion in patients with advanced cancer., Design: This is a randomized, double-blind crossover clinical trial to evaluate the efficacy of OTFC in dyspnea on exertion after the completion of a 6-minute walk test (6MWT). All patients were attended in 2011 by the Palliative Care Supportive Team from Badajoz. In visit 1, patients were randomly assigned to 1 of the 2 treatment groups. In visit 2, the patients who had been receiving the investigational product were given placebos and vice versa., Results: Thirteen patients were recruited (26 6MWT), with a mean age of 65 years. Of the patients, 11 (76%)were males and lung cancer was the most frequently represented etiology. The patients were classified into 3e categories: better response in the first period, the same response in both the periods, and better response in the second period. No differences between the treatments were demonstrated (P: 1). There were no differences in changes in oxygen saturation (P: .7541) nor in the distance walked in the different sequences (P: .6550). No significant differences were found in relation to the Edmonton Symptom Assessment System, either before or after the 6MWT (P: .1234). No secondary effects associated with the medication were observed., Conclusion: It could not be demonstrated that the OTFC improved exertion dyspnea in patients with advanced cancer. A placebo effect was observed in all the patients., (© The Author(s) 2013.)

The purpose of this study was to assess the effects of hip belt use and load placement in a backpack on perceived exertion and postural stability. Thirty participants were instructed to stand on a force plate and walk along a designated route under five conditions: unloaded, high-load placement, low-load placement, hip belt on and hip belt off. The average velocity and sway area from the force plate were measured. Participants also rated their perceived stability and exertion. Compared to the unloaded condition, all loaded conditions significantly increased average velocity, sway area, perceived stability and exertion. Hip belt use did not affect average velocity and sway area; however, participants reported higher levels of stability and lower levels of exertion with hip belt use. Load placement did not affect average velocity, sway area, perceived stability or exertion. This study showed that wearing a backpack loaded to 20% of body weight reduced postural stability, while manipulation of load placement in a backpack did not affect subjective and objective measures of postural stability. Also, hip belt use only improved subjective measures of postural stability.