Effect of the subjective intensity of fatigue and interoception on perceptual regulation and performance during sustained physical activity

BACKGROUND: The subjective experience of fatigue impairs an individual’s ability to sustain physical endurance performance. However, precise understanding of the specific role perceived fatigue plays in the central regulation of performance remains unclear. Here, we examined whether the subjective intensity of a perceived state of fatigue, pre-induced through prior upper body activity, differentially impacted performance and altered perceived effort and affect experienced during a sustained, isometric contraction in lower body. We also explored whether (cardiac) interoception predicted the intensity of experienced perceptual and affective responses and moderated the relationships between constructs during physical activity. METHODS: Using a repeated-measures study design, thirty male participants completed three experimental conditions, with the intensity of a pre-induced state of fatigue manipulated to evoke moderate (MOD), severe (SEV) and minimal (control; CON) intensity of perceptions prior to performance of the sustained contraction. RESULTS: Performance of the sustained contraction was significantly impaired under a perceived state of fatigue, with reductions of 10% and 14% observed in the MOD and SEV conditions, respectively. Performance impairment was accompanied by greater perceived effort and more negative affective valence reported during the contraction. However, effects were limited to comparisons to CON, with no difference evident between the two experimental trials (i.e. MOD vs. SEV). Individuals’ awareness of their accuracy in judging resting heartbeats was shown to predict the subjective intensity of fatigue experienced during the endurance task. However, interoception did not moderate the relationships evident between fatigue and both perceived effort and affective valence. CONCLUSIONS: A perceived state of fatigue limits endurance performance, influencing both how effortful activity is perceived to be and the affective experience of activity. Though awareness of interoceptive representations of bodily states may be important to the subjective experience of fatigue, interoception does not modulate the relationships between perceived fatigue and other perceptual (i.e. effort) and affective constructs

The effects of direct current stimulation on exercise performance, pacing and perception in temperate and hot environments

Background. Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulatory technique and has previously been shown to enhance submaximal exercise by reducing rating of perceived exertion (RPE). The present study examined the effects of tDCS on high-intensity self-paced exercise in temperate conditions and fixed followed by maximal exercise in the heat; it was hypothesised performance and RPE would be altered. Methods. Two separate studies were undertaken in which exercise was preceded by 20-minutes of sham tDCS (SHAM), or anodal tDCS (TDCS). Study 1: six males completed a 20-km cycling time trial, on two occasions. Power output (PO), RPE, O2 pulse, and heart rate (HR) were measured throughout. Study 2: eight males completed fixed intensity cycling exercise at 55% of a pre-determined maximal power output (PMax) for 25-minutes before undertaking a time to exhaustion test (TTE; 75% PMax) in hot conditions (33°C), on two occasions. Test duration, heart rate, thermal and perceptual responses were measured. Study specific and combined statistical analyses was undertaken and effect sizes established.. Results. Study 1: mean PO was not improved with the tDCS (197 ± 20 W) compared to SHAM (197 ± 12 W) and there were no differences in pacing profile HR, O2 pulse or RPE (p > .05). Study 2: TTE duration (SHAM 314 ± 334 s cf 237 ± 362 s tDCS), thermal, heart rate and perceptual responses were unchanged by tDCS compared to SHAM (p > .05). When combined, performance in the SHAM trial tended to better than the tDCS. Conclusion. tDCS did not influence cycling performance (study 1) exercise tolerance (study 2) or perception (studies 1&2). tDCS does not appear to facilitate high intensity exercise performance or exercise performance in the heat

Physiotherapy Outcomes Are Associated With Shorter Waiting Times, More Treatment Sessions and Younger Age:Analysis of a Clinical Database

Background: Musculoskeletal (MSK) conditions affect over 20.3 million people in the UK, presenting a substantial economic impact on health and social services. Physiotherapy can alleviate MSK conditions, especially if delivered in the acute or sub-acute period. However, patients often present after significant waiting times. Objectives: Our analysis examined how waiting times and the number of treatments influenced physiotherapy outcomes for MSK conditions. Design: Retrospective analysis of the Data for Impact, Physio First dataset. Methods: Logistic regression models assessed the effects of symptom duration, treatment frequency, and other variables on pain, Patient-Specific Functional Scores (PSFSs), and Goal Achievement (GA). Results: Analysis of 15,624 patient records showed that patients treated within two weeks of symptom onset were more likely to have favourable outcomes in pain (odds ratio [OR] = 2.01, 95% Confidence Interval [95% CI] = 1.65–2.45), PSFS (OR = 1.80, 95% CI = 1.55–2.08), and GA (OR = 1.74, 95% CI = 1.51–2.01) compared to those treated after longer durations. Receiving four or more treatment sessions significantly improved outcomes compared with only one session (pain: OR = 4.64, PSFS: OR = 5.72, GA: OR = 1.94, all p's &lt; 0.001), with no additional benefits beyond four sessions. Younger age was associated with better outcomes (approximately OR = 0.99 per year age difference). Other findings included better outcomes in males and in those with fewer previous episodes of the condition. Conclusions: Shorter waiting times, a greater number of treatments, and younger patient age are associated with better physiotherapy outcomes for MSK conditions.</p

Towards the unity of pathological and exertional fatigue: A predictive processing model

Fatigue is a common experience in both health and disease. Pathological (i.e. prolonged or chronic) and transient (i.e. exertional) fatigue symptoms are traditionally considered distinct, compounding a separation in research fields interested in the study of fatigue. Within the clinical neurosciences, nascent frameworks position pathological fatigue as a product of inference derived through hierarchical predictive processing. The metacognitive theory of dyshomeostasis (Stephan et al., 2016) states that pathological fatigue emerges from the detection of a persistent mismatch between prior interoceptive predictions and ascending sensory evidence (i.e. prediction error). Evaluation of allostatic control during the experience of dyshomeostasis signals low evidence for internal generative models, which undermine an agent’s feeling of mastery over the body and is experienced phenomenologically as fatigue. The same metacognitive mechanisms have been excluded as a theoretical account for the acute, transient experience of exertional fatigue. Here, we contest this proposition and offer a more parsimonious account of fatigue in which a common mechanism (i.e. the loss of certainty or confidence in allostatic predictions) is at the core of both pathological and non-pathological, exertional symptoms of fatigue

Does depression experienced by mothers leads to a decline in marital quality: a 21-year longitudinal study

Marital conflict and/or marital breakdown are known pathways to the onset of depression. Few studies however have examined the possibility that depression can lead to a decrease in marital quality and an increase in marital breakdown. Depression may be an important pathway to a decline in martial quality

Supporting Advancement in Weather and Water Prediction in the Upper Colorado River Basin: The SPLASH Campaign

Water is a critical resource that causes significant challenges to inhabitants of the western United States. These challenges are likely to intensify as the result of expanding population and climate-related changes that act to reduce runoff in areas of complex terrain. To better understand the physical processes that drive the transition of mountain precipitation to streamflow, the National Oceanic and Atmospheric Administration has deployed suites of environmental sensors throughout the East River watershed of Colorado as part of the Study of Precipitation, the Lower Atmosphere, and Surface for Hydrometeorology (SPLASH). This includes surface-based sensors over a network of five different observing sites, airborne platforms, and sophisticated remote sensors to provide detailed information on spatiotemporal variability of key parameters. With a 2-yr deployment, these sensors offer detailed insight into precipitation, the lower atmosphere, and the surface, and support the development of datasets targeting improved prediction of weather and water. Initial datasets have been published and are laying a foundation for improved characterization of physical processes and their interactions driving mountain hydrology, evaluation and improvement of numerical prediction tools, and educational activities. SPLASH observations contain a depth and breadth of information that enables a variety of atmospheric and hydrological science analyses over the coming years that leverage collaborations between national laboratories, academia, and stakeholders, including industry