Subjective Measures Of Fatigue Research Articles

Music as a countermeasure to fatigue: A driving simulator study

Listening to music while driving is a commonly adopted fatigue-coping strategy, yet its effectiveness has been explored in only a limited number of studies. Here, we aim to evaluate its impact on passive task-related driving fatigue, as measured by a set of both objective and subjective indicators.A driving simulator experiment was conducted involving 60 participants, who completed a 50-minute driving task on a monotonous highway scenario. The participants were divided into a control group, which did not listen to any music, and an experimental group, which drove for 20 min without music and then listened to a self-selected music playlist played at the preferred intensity for the remaining 30 min.Results show that music had a positive acute effect on objective measurements of driving fatigue. However, this effect was transient (15–25 min duration), and more prominently observed in subjective measures of fatigue. An exploratory analysis of song features suggests that higher intensity, higher tempo, more danceable, and less instrumental music tend to be more effective. These findings indicate that listening to music can serve as a viable short-term countermeasure to driving fatigue.

Trajectories of fatigue and related outcomes following mild acquired brain injury: a multivariate latent class growth analysis.

Fatigue is a common symptom following acquired brain injury although the severity and course differs for many individuals. This longitudinal study aimed to identify latent trajectory classes of fatigue and associated outcomes following mild brain injury. 204 adults with mild traumatic brain injury (159; 78%) or minor stroke (45; 22%) were assessed 4 times over 1 year. Subjective measures of fatigue, anxiety, depression, cognitive complaints and societal participation were collected. Multivariate Latent Class Growth Analysis identified classes of participants with similar longitudinal patterns. Demographic and injury characteristics were used to predict class membership. Analysis revealed four classes. Class 1 (53%) had mild, decreasing fatigue with no other problems. Class 2 (29%) experienced high persistent fatigue, moderate cognitive complaints and societal participation problems. Class 3 (11%) had high persistent fatigue with anxiety, depression, cognitive complaints and participation problems. Class 4 (7%) experienced decreasing fatigue with anxiety and depression but no cognitive or participation problems. Women and older individuals were more likely to be in class 2. Half the participants had a favourable outcome while the remaining classes were characterised by persistent fatigue with cognitive complaints (class 2), decreasing fatigue with mood problems (class 4) or fatigue with both cognitive and mood problems (class 3). Fatigue treatment should target combinations of problems in such individual trajectories after mild brain injury.

Subjective fatigue in individuals with anxiety and mood disorders correlates with specific traits of obsessive-compulsive personality disorder

Fatigue is a common debilitating symptom in individuals with anxiety and mood disorders, also known as common mental disorders (CMD). Aspects of fatigue are seen to be independently associated with the presence of obsessive-compulsive personality disorder (OCPD) in individuals with CMD. However, the relationship between different traits of OCPD and fatigue is still under-researched. Therefore, the aim of our study was to examine the associations between individual OCPD traits and fatigue in those with CMD. This cross-sectional study investigated 203 individuals (76.8% female, mean age 40.8 ± 11.8) attending a stress-related disorders day care unit. Participants were evaluated for OCPD traits by using the Compulsive Personality Assessment Scale and completed the Multidimensional Fatigue Inventory-20. Out of 203 participants, 42 (20.7%) fulfilled operational criteria for OCPD (73.8% female). Participants with OCPD had greater reduced motivation, mental and physical fatigue scores than those without OCPD (13.2 ± 3.6 vs. 14.5 ± 3.6, p = 0.035; 14.4 ± 4.3 vs. 16.1 ± 3.5, p = 0.023; 13.5 ± 4.3 vs. 15.0 ± 4.3, p = 0.049, respectively). In individuals with OCPD, higher levels of rigidity correlated with physical fatigue (ρ = 0.463, p = 0.002) and reduced activity (ρ = 0.363, p = 0.018), while preoccupation with details was associated with reduced motivation (ρ = 0.437, p = 0.004). In conclusion, in individuals with CMD and comorbid OCPD, several OCPD traits were significantly related to subjective measures of fatigue. As traits are considered stable features, there results suggest they might play a causative role in generating subjective fatigue in CMD.

Fatigue Prediction in Outdoor Running Conditions using Audio Data.

Although running is a common leisure activity and a core training regiment for several athletes, between 29% and 79% of runners sustain an overuse injury each year. These injuries are linked to excessive fatigue, which alters how someone runs. In this work, we explore the feasibility of modelling the Borg received perception of exertion (RPE) scale (range: [6]-[19] [20]), a well-validated subjective measure of fatigue, using audio data captured in realistic outdoor environments via smartphones attached to the runners' arms. Using convolutional neural networks (CNNs) on log-Mel spectrograms, we obtain a mean absolute error (MAE) of 2.35 in subject-dependent experiments, demonstrating that audio can be effectively used to model fatigue, while being more easily and non-invasively acquired than by signals from other sensors.

The Correlation Between Static Fatigue Testing and the Quantitative Myasthenia Gravis Score and Activities of Daily Living Profile

Fatigue is a common symptom in myasthenia gravis (MG), but both objective and subjective measures of fatigue are poorly studied in the disease. We conducted a pilot study of static fatigue testing (SFT) in a group of MG patients, using an isometric quantified muscle analysis computer system. Results from sustained isometric contraction of 5 muscle groups in 77 patients were correlated to the Quantitative MG Score (QMG) and the Activities of Daily Living Profile (MG-ADL), two commonly used outcome measures. Pearson correlation coefficients for the SFT were highest (0.33) for hand grip for both the QMG and MG-ADL. Correlations were quite poor for the proximal muscle groups and ankle dorsiflexion. More work is needed to develop objective and subjective measures of fatigue in MG.

Did rest breaks help with acute fatigue among nursing staff on 12-h shifts during the COVID-19 pandemic? A cross-sectional study.

AimThis study aimed to explore whether 30‐min rest breaks were as effective at lowering acute fatigue among 12‐h shift hospital nursing staff who cared for patients with COVID‐19 as among those who did not.DesignThe study was cross‐sectional in design.MethodsData from the SAFE‐CARE study collected online between May and June 2020 were used. A subsample (N = 338) comprised of nursing staff who reported working 12‐h shifts, and providing direct patient care in hospitals was used in this study. Data on socio‐demographics, work and rest breaks, and subjective measures of fatigue, psychological distress, sleep and health were used. Hierarchical multiple linear regression followed by stratified analyses was conducted to explore the relationships between rest breaks and acute fatigue among nursing staff groups with and without COVID‐19 patient care.ResultsThe sample, on average, had high acute fatigue. Around 72% reported providing care to patients with COVID‐19, and 71% reported taking rest breaks ‘sometimes’, ‘often’ or ‘always’. In the group that cared for patients with COVID‐19, there was no significant relationship between rest breaks and acute fatigue (p = .507). In the group that cared for patients hospitalized for other reasons, rest breaks were associated with lower acute fatigue (p = .010).ConclusionOur findings showed both the importance and inadequacy of rest breaks in reducing acute fatigue. The process of within‐work recovery is complex, and routine rest breaks should be facilitated by nursing management on hospital units during and after the COVID‐19 pandemic.ImpactRest breaks may present an effective strategy in lowering fatigue. Although rest breaks were not associated with less fatigue among staff caring for patients with COVID‐19, other co‐workers experienced some fatigue recovery. For frontline nursing staff, routine rest breaks are encouraged, and a systematic evaluation pertaining the sufficiency of rest breaks during high work demands in future research is needed.

Efficacy of Iron Therapy on Fatigue and Work Capacity in Non-Anemic Iron Deficient Adults: A Systematic Review of Randomized Controlled Trials

INTRODUCTION: Iron supplementation in iron deficiency anemia is standard practice, but the benefits of iron supplementation in iron deficient non-anemic (IDNA) individuals remains controversial. We conducted a systematic review and meta-analysis to identify the effects of iron therapy on fatigue and work capacity in iron deficient non-anemic adults.METHODS: We included randomized controlled trials of adults (≥18 years) who were iron deficient but non-anemic. Interventions included oral, intramuscular or intravenous iron supplementation; all therapy doses, frequencies and durations were included. We included trials that evaluated outcomes at least 1 month from the initiation of iron therapy. Comparators included placebo or active therapy. Our primary outcome measures were self-reported fatigue and objective measures of work capacity. Secondary outcomes included the incidence of anemia, change in hemoglobin concentration and serum ferritin, and the incidence of adverse outcomes including iron toxicity, constipation, diarrhea, gastrointestinal intolerance and nausea. We searched Medline, Embase, CENTRAL, CINAHL, SportDiscus, and CAB Abstracts from inception to October 31, 2016. We searched the World Health Organization's ICTRP for relevant ongoing trials and performed forward searches of included trials and relevant reviews in Web of Science. We assessed internal validity of included trials using the Cochrane Risk of Bias tool, and the external validity using the GRADE methodology.RESULTS: From 11580 citations we included 18 unique trials, and 2 companion papers enrolling 1162 patients (Table 1). Trials were published between 1989 and 2015, and all trials were published in peer-reviewed journals. Exclusively healthy females (aged 17 to 55 years old) with varying levels of fitness (sedentary to well-trained) were enrolled in all but three studies. Iron interventions consisted of iron supplementation administered orally, intramuscularly or intravenously. Of the trials evaluating oral supplements, all but one used ferrous sulfate (13 trials, 721 participants). Intravenous iron was administered in three trials (395 participants), and intramuscular iron in one trial (16 participants). In trials using oral iron, the mean daily elemental iron dose was 86.9mg (± 49.1mg; range: 16 to 200mg). In trials reporting intravenous iron, the mean daily elemental iron dose was 566mg (± 330mg; range 200 to 1000mg) and mean total elemental iron dose 767mg (± 206mg; range 500 to 1000mg). Among all studies, the mean duration of iron therapy was 46 days (± 30 days; range 1 to 112 days), and mean duration of follow-up was 57 days (± 24 days; range 28 to 112 days). Fatigue was evaluated in four trials enrolling 714 participants. Iron supplementation was associated with a reduction in subjective measures of fatigue when assessed by either the Piper Fatigue Scale (PFS), the Current and Past Psychological State scale (CAPPS), visual analog scale or Brief Fatigue Inventory questionnaire (BFI) (SMD -0.38; 95% CI -0.52 to -0.23; I2 0%). Work capacity was reported in 10 trials (291 participants); all but one of the trials employed at least one of three common aerobic tests of work capacity: time trial, time to exhaustion, or VO2 max performance from a graded exercise test. In two trials (79 participants) that used 15 km time trials, iron supplementation was not associated with improved exercise capacity (SMD -0.09; 95% CI -0.53 to 0.35; I2 0%). In four trials (69 participants) that used time-to-exhaustion tests, iron supplementation did not significantly improve exercise capacity (SMD 0.25; 95% CI -0.22 to 0.73; I2 0%). Nine trials (235 participants) reported VO2 max as a surrogate measure of work capacity. Iron supplementation did not increase VO2 max (SMD 0.11; 95% CI -0.15 to 0.37; I2 0%).CONCLUSION: In iron deficient non-anemic adults, iron supplementation is associated with reduced subjective measures of fatigue, but not with objective improvements in work capacity. Given the global prevalence of both iron deficiency and fatigue, patients and practitioners could consider a course of iron supplementation to improve symptoms of fatigue in presence or absence of documented anemia. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Differential effects of modafinil on performance of low-performing and high-performing individuals during total sleep deprivation

BackgroundIndividual responses to the effects of inadequate sleep have been well documented; some people are more vulnerable to the effects of sleep loss than others. Fatigue-vulnerable individuals generally require access to effective fatigue countermeasures; however, the question arises as to whether these fatigue-vulnerable individuals receive the same benefits shown in group efficacy data. The present study administered modafinil to individuals to determine its differential effects on performance of best and worst performers during sleep deprivation. MethodsA sample of 22 men, age 21–40 yrs., was tested on 2 separate occasions during which they were kept awake for 36 h. During one period they received 200 mg modafinil; during the other they received placebo. Participants were tested on a variety of tasks while rested and at 5-hr intervals across the continuous wakefulness period. Performance for each cognitive task and subjective measure of fatigue from the placebo period was used to group individuals into high (HP) or low performance (LP) groups to indicate fatigue vulnerability for each task. ResultsResults indicated that on the MTS task, the HP group performed the same throughout the testing period, regardless of whether they received modafinil or not. However, the LP group significantly improved after receiving modafinil compared to placebo. Performance on the PVT showed the HP group had a small decrease in the number of lapses after receiving modafinil compared to placebo, whereas the LP group had a large decrease in lapses after receiving modafinil compared to placebo. Performance on the RDM showed no difference between groups, regardless of drug condition. Groups did not differ after receiving modafinil on subjective fatigue measured by the POMS. ConclusionsDepending on the task, HP individuals did not benefit substantially when administered modafinil compared to placebo. However, the LP individuals improved after receiving modafinil compared to placebo.

Rescuer Exertion and Fatigue Using Two-Thumb vs. Two-Finger Method During Simulated Neonatal Cardiopulmonary Resuscitation.

Background: Rescuer fatigue during neonatal CPR can affect CPR quality leading to reduced cerebral and myocardial perfusion.Aim: To investigate rescuer fatigue during simulated neonatal CPR using both objective (heart rate and cardiac output) and subjective measures.Methods: A randomized crossover manikin study performed. Nineteen doctors working in neonatology were randomized to (a) two-thumb term, (b) two-finger term, (c) two-thumb preterm, or (d) two-finger preterm group. Cardiac output and heart rate were measured with a non-invasive cardiac output monitor. A Likert scale assessed participants' level of perceived exertion.Results: In the preterm group, the mean change in HR from rest to 5 min in the TT group was 11.58 bpm (SD 6.22) vs. 9.94 bpm (SD 8.48), (p-value 0.36). There was no difference in change in CO, 2.10 (SD 1.15) in the TT group vs. 1.39 (SD 1.63) in TF group (p value 0.23). There was no difference in BORG RPE rating. In the term group, the mean change in HR from rest to 5 min was 15 bpm (SD 8.40) in TT group and 13 bpm (SD 7.86) in TF group, (p-value 0.416). The median change in CO from rest to 5 min was 1.50 (0.78 to 2.42 IQR) in TT group vs. 1.60 (0.65 to 3.0 IQR) in TF group.Conclusion: Providing chest compressions is associated with an increase in both heart rate and cardiac output. We did not identify difference between objective and subjective measures of fatigue between either technique in a preterm or term model.

Physiological and perceptual responses of youth soccer players to an intensified period of competition

Intensified periods of competition create large increase in physical workload and can expose soccer players to numerous playing styles. The purpose of the study was to investigate the response of youth soccer players to an intensified period of competition and assess whether initial fitness influenced outcomes. Elite males across two consecutive years (n1 = 18, n2 = 18) were assessed for lower body strength and high-intensity endurance. Objective and subjective measures of fatigue were collected throughout five-day international tournaments using countermovement jumps (CMJ), a perceptual wellness questionnaire and match GPS data. Mixed effects models quantified the effects of time and fitness on outcomes. In general, results were consistent across both years. No significant interaction effects were obtained between time and fitness variables for any outcome ([Formula: see text] ≤ 6.5; p ≥ .225). CMJ height and power remained consistent across both tournaments ([Formula: see text] ≤ 5.3; p ≥ .262). In contrast, significant ([Formula: see text] ≥ 17.7; p < .003) effects of time were obtained for GPS data with metrics exhibiting U-shape patterns with values returning to initial levels during final games. Greater variation was obtained for perceptual wellness data; however, responses to general muscle soreness and stress levels showed consistent decreases across both years ([Formula: see text] ≥ 12.7; p ≤ .013). Practitioners should be aware that basic measures collected from CMJ and GPS data may not be sensitive to fatigue accrued in youth soccer players across intensified periods of competition. In contrast, simple perceptual measures including general muscle soreness and stress may be more sensitive and assist with implementation of active recovery or load management strategies.

The effect of an ultra-endurance running race on heart rate variability

The aim of this study was to investigate the effect of an ultra-marathon on heart rate variability (HRV) and psychometric indices in endurance runners. In addition, we aimed to determine the magnitude of change and subsequent recovery for 7days following the race. Recreationally trained runners (n = 13 (8M); age = 36.6 ± 7.6years; height = 174 ± 9cm; weight = 70.5 ± 9.3kg) completed measures of HRV upon waking in the morning for 1week prior to and 1week following a 64-km running race. Profile of mood states, wellbeing, and muscular soreness were also measured throughout the study period to further contextualise recovery. An increase in heart rate accompanied by decreased LnSDNN, LnRMSSD, LnLF, LnHF, and LnLF/HF from baseline were observed 1day post-race (p < 0.05). Indices of HRV had returned to baseline on day 2 of recovery. Perceptual fatigue and muscle soreness increased post-race (immediately following and on day 1 of recovery) (p < 0.05) and took until day 5 of recovery to return to baseline. The results indicate that cardiac autonomic control is significantly altered in response to a 64km ultra-marathon. Specifically, parasympathetic activity is suppressed. The change in autonomic control was relatively short-lived, and parasympathetic-related indices had returned to baseline 2days after the event. Subjective measures of fatigue and wellbeing suggest that athletes were not completely recovered until day 5 post-event, with muscular soreness remaining prominent during this period. A combination of physiological and psychological parameters is important to contextualise recovery in ultra-endurance runners.

Cancer-related fatigue stratification system based on patient-reported outcomes and objective outcomes: A cancer-related fatigue ambulatory index.

Although breast cancer mortality is decreasing, morbidity following treatment remains a significant issue, as patients face symptoms such as cancer-related fatigue (CRF). The aim of the present study is to develop a classification system that monitors fatigue via integration of an objective clinical assessment with patient self-report. Forty-three women participated in this research. Participants were post-treatment breast cancer survivors who had been surgically treated for their primary tumour with no evidence of neoplastic disease at the time of recruitment. Self-perceived fatigue was assessed with the Spanish version of the Piper Fatigue Scale-Revised (R-PFS). Objective fatigue was assessed by the 30 second Sit-to-Stand (30-STS) test. Confirmatory factor analysis was done with Maximum Likelihood Extraction (MLE). Internal consistency was obtained by Cronbach's α coefficients. Bivariate correlation showed that 30-STS performance was negatively-inversely associated with R-PFS. The MANOVA model explained 54.3% of 30-STS performance variance. Using normalized scores from the MLE, a classification system was developed based on the quartiles. This study integrated objective and subjective measures of fatigue to better allow classification of patient CRF experience. Results allowed development of a classification index to classify CRF severity in breast cancer survivors using the relationship between 30-STS and R-PFS scores. Future research must consider the patient-perceived and clinically measurable components of CRF to better understand this multidimensional issue.

The Role of Motivation as a Factor in Mental Fatigue.

Objective:The aim of this study was to assess motivation as a factor in mental fatigue using subjective, performance, and physiological measures.Background:Sustained performance on a mentally demanding task can decrease over time. This decrement has two possible causes: a decline in available resources, meaning that performance cannot be sustained, and decrement in motivation, meaning a decline in willingness to sustain performance. However, so far, few experimental paradigms have effectively and continuously manipulated motivation, which is essential to understand its effect on mental fatigue.Method:Twenty participants performed a working memory task with 14 blocks, which alternated between reward and nonreward for 2.5 hr. In the reward blocks, monetary rewards could be gained for good performance. Besides reaction time and accuracy, we used physiological measures (heart rate variability, pupil diameter, eyeblink, eye movements with a video distractor) and subjective measures of fatigue and mental effort.Results:Participants reported becoming fatigued over time and invested more mental effort in the reward blocks. Even though they reported fatigue, their accuracy in the reward blocks remained constant but declined in the nonreward blocks. Furthermore, in the nonreward blocks, participants became more distractable, invested less cognitive effort, blinked more often, and made fewer saccades. These results showed an effect of motivation on mental fatigue.Conclusion:The evidence suggests that motivation is an important factor in explaining the effects of mental fatigue.

Core temperature is not elevated at rest in people with relapsing-remitting multiple sclerosis

PurposeTo reassess the notion that people with multiple sclerosis (MS) do not demonstrate an elevated resting core temperature when measured using best-practice precision thermometry. MethodAcross two international data collection sites (Australia and USA), twenty-eight relapsing-remitting MS patients and 27 aged-matched controls (CON) were exposed to either 30 °C, 30% relative humidity (RH) (Sydney) or 25 °C, 30% RH (Dallas). Resting rectal (Tre) and esophageal (Teso) temperature and resting oxygen consumption (VO2) was measured in MS (n = 28) and CON (n = 27) groups who completed the 25 °C and 30 °C trials. Tympanic membrane (Ttym) temperature was measured in MS (n = 16) and CON (n = 15) groups in the 30 °C condition. A modified fatigue impact scale (MFIS) questionnaire was used to assess subjective measures of psychosocial, physical and cognitive fatigue in the 30 °C condition. ResultsIrrespective of ambient temperature, no group differences were observed for Tre (MS: 37.07 ± 0.30 °C; CON: 37.18 ± 0.30 °C; P = 0.29), Teso (MS: 36.84 ± 0.42 °C; CON: 36.92 ± 0.29 °C; P = 0.36) or resting VO2 (MS: 3.89 ± 0.18 ml⋅kg−1⋅min−1; CON: 3.98 ± 0.17 ml⋅kg−1⋅min−1; P = 0.67). Similarly, no group differences were observed for Ttym (MS: 36.52 ± 0.38 °C; CON: 36.61 ± 0.33 °C; P = 0.55) in the 30 °C condition. Resting Tre did not correlate with subjective measures of fatigue: physical: r = -0.11, P = 0.67; cognitive: r = -0.14, P = 0.60; and psychosocial: r = 0.05, P = 0.84. ConclusionContrary to recent reports, resting core temperature is not elevated in relapsing-remitting MS patients compared to healthy controls when measured using precision thermometry. Furthermore, no association was observed between resting Tre and any subjective measures of fatigue in a subset of participants with MS.

Perceived Versus Performance Fatigability in Patients With Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a chronic, inflammatory disease that affects 1% of the general population. Fatigue is a common complaint of patients with RA, however their perceived fatigue may be more exacerbated than objective measures of fatigue may indicate. The assessment of fatigue is made complex due to inconsistent and vague terms used to define fatigue, and the task dependence of fatigability. Fatigue is defined as a state of exhaustion and decreased strength, while fatigability indicates an individual’s susceptibility to fatigue. In order to offer some clarity to the manifestation of fatigue in clinical populations, in this review we outline that fatigue should be described with subsections that are related to the symptom, such as: perceived fatigability and performance fatigability. Where perceived fatigability indicates the subjective state of the individual and thus involves the individual’s subjective measure of fatigue, performance fatigability would be measured through clinical and laboratory-based assessments that quantify the functional decline in performance. This review describes RA and the various neuromuscular changes associated with the disease that can lead to alterations in both perceived and performance fatigue. From there, we discuss fatigue and RA, how fatigue can be assessed, effects of exercise interventions on RA symptoms and fatigue, and recommendations for future studies investigating subjective and objective measures of fatigability.

MENTAL FATIGUE DOES NOT AFFECT HEART RATE RECOVERY BUT IMPAIRS PERFORMANCE IN HANDBALL PLAYERS

ABSTRACT Introduction: This study involved an analysis of the impact of mental fatigue on heart rate recovery (HRR), subjective measures of fatigue and intermittent running performance in handball players. Objective: This study was aimed at (1) examining the effects of an induced state of mental fatigue on the aerobic performance of handball players, as measured by the Yo-Yo IR1 test, and (2) exploring possible changes in heart rate regulation through HRR analysis. Methods: Twelve handball players (age: 17.50 ± 3.63 years; 5 ± 2.2 years of practice) undertook a Yo-Yo IR1 test on two occasions, separated by an interval of at least 72 hours. The Yo-Yo IR1 test was preceded by a 30-min treatment, consisting of the Stroop Color-Word Test, to induce mental fatigue. Participants in the control condition watched an emotionally neutral video. Results: Higher ratings of mental fatigue and mental effort following the Stroop Test were observed for the experimental group. No differences in motivation were observed between conditions. Moreover, the induction of mental fatigue impaired running performance and led to a higher RPE during the Yo-Yo IR1 test. Notwithstanding, no changes in HRR or blood lactate levels were observed across conditions. Conclusion: Altogether, these results suggest that mental fatigue impairs intermittent running performance, without affecting HRR values. Level of Evidence III; Case-Control study.

Acute Effects Of A Multi-ingredient Pre-workout Supplement On 5-km Running Performance In Recreationally-trained Athletes

PURPOSE: The purpose of the present study was to examine the effects of an acute dose of a multi-ingredient, thermogenic, pre-workout supplement on 5-km running performance and subjective measures of fatigue. METHODS: Twenty aerobically-trained, college-aged males (n = 10, mean ± SD = 80.8 ± 6.1 kg) and females (n = 10, 64.5 ± 6.6 kg) completed two 5-km running races for time. During the first session, the subjects were randomly assigned to ingest the supplement or placebo 30 minutes prior to running a 5-km race as fast as possible. The supplement contained multiple ingredients including caffeine anhydrous (150 mg), beta alanine (1.6 g), arginine AKG (1.0 g), as well as tyrosine, L-carnitine, green coffee bean extract, and velvet bean extract at unspecified quantities. The placebo was a non-caloric mix that was matched for flavor and consistency. Subjects also completed a 5-point Likert scale (1 = low, 5 = high) questionnaire to determine feelings of fatigue immediately prior to ingesting the substance (baseline), 30 minutes post-ingestion (immediately pre-race), and 5 minutes post-race. For the second session, subjects ingested the opposite substance (supplement or placebo) and underwent the same testing procedures (including time of day) as the first session. Race times were compared between the supplement and placebo conditions using a paired-samples t-test. In addition, a two-way ANOVA with repeated measures was used to compare the feelings of fatigue among the conditions (supplement vs. placebo) at the common time points (baseline, pre-race, post-race). RESULTS: The results indicated there was no significant (P > 0.05) difference in 5-km race time between the supplement (23.62 ± 2.08 min) and placebo (23.51 ± 1.97 min) conditions. For the feelings of fatigue, there was no significant condition x time interaction or main effect for condition, but there was a main effect for time. Specifically, the marginal means (collapsed across conditions) for fatigue were significantly (P < 0.05) greater post-race (3.3 ± 0.8) than at baseline (2.3 ± 0.7) and pre-race (2.4 ± 0.6). CONCLUSIONS: The findings of the present investigation indicated that the pre-workout supplement provided no ergogenic effect on 5-km race time or feelings of fatigue when administered on an acute basis in recreationally-active males and females.

Efficacy of iron supplementation on fatigue and physical capacity in non-anaemic iron-deficient adults: a systematic review of randomised controlled trials

ObjectiveIron supplementation in iron-deficiency anaemia is standard practice, but the benefits of iron supplementation in iron-deficient non-anaemic (IDNA) individuals remains controversial. Our objective is to identify the effects of iron...

Cardiorespiratory dynamics of rescuers during cardiopulmonary resuscitation in a hypoxic environment

ObjectiveWe had previously experienced a case involving prolonged cardiopulmonary resuscitation (CPR) on Mt. Fuji (3776 m), demanding strenuous work by the rescuers. The objective of this study was to compare the effect of compression-only and conventional CPR on oxygen saturation of rescuers in a hypoxemic environment. MethodsChanges in percutaneous arterial oxygen saturation (SpO2) and heart rate during CPR action were measured in a hypobaric chamber with barometric pressure adjusted to be equivalent to 3700 m above sea level (630–640 hPa). Thirty-three volunteers performed CPR with or without breaths using a CPR mannequin. ResultsIn a 3700-m-equivalent environment, SpO2 was reduced only when CPR was performed without breaths (P < .05, one-way analysis of variance (ANOVA) post hoc Tukey test). Heart rate increased during CPR regardless of the presence or absence of breaths. Mean scores on the Borg scale, a subjective measure of fatigue, after CPR action in the 3700-m-equivalent environment were significantly higher (15 ± 2) than scores after CPR performed at sea level (11 ± 2, P < .01, paired t-test). No lethal dysrhythmia was found in subjects with a wearable electrode shirt. ConclusionsProlonged CPR at high altitude exerts a significant physical effect upon the condition of rescuers. Compression-only CPR at high altitude may deteriorate rescuer oxygenation, whereas CPR with breaths might ameliorate such deterioration.

Mental Fatigue Impairs Physical Performance in Young Swimmers.

This study aimed to investigate the impact of mental fatigue on heart rate variability, subjective measures of fatigue, and swimming performance in young athletes. Sixteen swimmers [15.45 (0.51) y old, 7.35 (2.20) y of swimming experience] performeda 1500-m time trial on 2 occasions separated by an interval of at least 72hours. The 1500-m swimming was preceded by a 30-minute treatment that consisted of performing the Stroop Color and Word test to induce mental fatigue (experimental trial) or watching an emotionally neutral video (control trial). Participants reported higher ratings of mental fatigue and mental effort following the Stroop test when compared with the control trial, but no differences in motivation were observed. The induction of mental fatigue impaired swimming performance, as evidenced by a slower time (1.2%) to complete the 1500-m trial. No intertrial differences were identified for rating of perceived exertion during the swimming test or in heart rate variability after the Stroop and swimming tests. The results indicate that induction of mental fatigue impairs 1500-m swimming performance without changing heart rate variability.