Effects of Repeated, Long-Duration Hyperoxic Water Immersions on Neuromuscular Endurance in Well-Trained Males.
ABSTRACT: Purpose:This study examined the effects of repeated long-duration hyperoxic water immersions (WIs) at 1.35 atmospheres absolute (ATA) on neuromuscular endurance performance. We hypothesized that over a 5-day period of consecutive, resting, long-duration hyperoxic WIs there would be a decrease to neuromuscular endurance performance and tissue oxygenation with the quadriceps muscle, but not with the forearm flexors. Methods:Thirteen well-trained, male subjects completed five consecutive 6-h resting WIs with 18-h surface intervals during the dive week while breathing 100% oxygen at 1.35 ATA. We assessed skeletal muscle endurance performance before and after each WI, and 24 and 72 h after the final WI. Muscular endurance assessments included 40% maximal handgrip endurance (MHE) and 50-repetition maximal isokinetic (IK) knee extensions. Near-infrared spectroscopy (NIRS) was used to measure muscle oxidative capacity (MOC) of the vastus lateralis and localized muscle tissue oxygenation of the vastus lateralis and flexor carpi radialis. Simultaneously, we measured brachioradialis neuromuscular activation by surface electromyography (SEMG). Results:MHE time-to-fatigue performance declined by 15% at WI 3 (p = 0.009) and by 17% on WI 5 (p = 0.002). Performance continued to decline by 22% at 24-h post-WI (p < 0.001) and by 12% on 72-h post-WI (p = 0.019). Fifty-repetition IK knee extension total work decreased by 5% (p = 0.002) on WI 3, and was further reduced by 7.5 and 12.3% (p = 0.032) at pre-WI 5 and 24-h post-WI, respectively. However, the rate of fatigue was 8 (p = 0.033) and 30% (p = 0.017) lower at WI 3 and 24-h post-WI when compared to WI 1, respectively, demonstrating the muscles were still fatigued from the previous hyperoxic WIs. We detected no significant limitations in oxygen off-loading kinetics during the exercise or MOC measurements. Conclusion:Repeated, resting, long-duration hyperoxic WIs caused significant reductions to muscular endurance but not to indirect measures of oxygen kinetics in load bearing and non-load bearing muscles.
Project description:<h4>Objectives</h4>This study aimed to determine the effect of occupational safety and health (OSH) education during formal schooling on the incidence of workplace injuries (WIs) in young people starting their careers. We hypothesised that young people who had received OSH education during their schooling would have fewer WIs than those who received no OSH education. Secondary objectives focused on the effect of 'first aid at work' training during schooling and the conditions encountered on arrival in the company (occupational hazard information, safety training and job task training) on WI occurrence.<h4>Design</h4>Prospective cohort study.<h4>Participants</h4>From 2009 to 2012, French apprentices and students at the end of their schooling and starting their careers were included.<h4>Outcomes</h4>Occurrence of WIs.<h4>Methods</h4>At the time of inclusion, information about school courses and personal characteristics were collected, and subsequent half-yearly contacts gathered information relating to work and personal data. During the 2-year follow-up, WIs were directly reported by participants and were identified by searching the French National Health Insurance Funds' databases listing compulsory WI declarations.<h4>Results</h4>755 participants reported holding 1290 jobs. During follow-up, 158 WIs were identified, corresponding to an incident rate of 0.12 (0.10 to 0.14) WIs per full-time worker. Subjects who reported having received OSH education at school had two times less WIs than those declaring not having received OSH education (incidence rate ratio (IRR) 0.51, 0.00 to 0.98). A lower WI risk was observed for participants who received the 'first aid at work' training (IRR=0.68, 0.00 to 0.98). The conditions on arrival in company were not associated with WIs occurrence.<h4>Conclusion</h4>In France, the OSH education provided to apprentices and students is mostly broader than the specific risks related to future jobs. Our results highlight the advantages of reinforcing this approach.
Project description:<h4>Background</h4>The Short Physical Performance Battery (SPPB) is advocated as a screening tool in geriatric care for predicting future disability. We aimed to identify the leg neuromuscular attributes to be targeted in rehabilitative care among older adults with poor SPPB scores.<h4>Methods</h4>Boston Rehabilitative Impairment Study of the Elderly (Boston RISE) participants (n = 430) underwent assessment of neuromuscular attributes (leg strength, leg velocity, trunk extensor endurance, knee flexion range of motion [ROM], ankle ROM, and foot sensation). Linear regression models examined association between each neuromuscular attribute and SPPB, adjusting for age, race, gender, comorbidity, body mass index, depression, cognition, and other neuromuscular attributes.<h4>Results</h4>Participants with 1 SD unit higher leg strength, leg velocity, and trunk extensor endurance had 0.52, 0.30, and 0.52 points higher SPPB total score. Participants with ankle ROM impairment and foot sensory loss had 0.43 and 0.57 lower SPPB total score compared with those without these. Leg strength and trunk extensor endurance were associated with balance; leg velocity, trunk extensor endurance, and ankle ROM were associated with gait speed; and strength, trunk extensor endurance, knee ROM, and feet sensation were associated with chair stand score. Neuromuscular attributes, along with covariates, explained 40.4% of the variance in the total SPPB score, a substantial increase over the 22.7% variance explained by covariates alone.<h4>Conclusions</h4>Neuromuscular attributes affect mobility performance in older patients as measured by the SPPB. Specific impairments are associated with poor performance in specific component scores. Assessment of the SPPB components and rehabilitation of associated impairments may help improve the functional performance among older adults.
Project description:Low-intensity training involving high repetitions is recommended to enhance muscular endurance. Hyperoxic conditions could increase the number of repetitions until exhaustion and thereby improve the results of muscular endurance training. This study aimed to investigate the acute effects of hyperoxia on dynamic muscular endurance, and determine individual factors that may be related to these effects. A single-blinded, counterbalanced crossover design was used. Twenty-five young men performed repetitions of the one-arm preacher curl at 30% of their 1-repetition maximum until exhaustion under hyperoxic and normoxic conditions. The maximum number of repetitions was recorded as an index of muscular endurance. Electromyogram (EMG) and near-infrared spectroscopy parameters were measured in the biceps brachii. The maximum number of repetitions was greater (P < 0.001) under hyperoxic conditions (132 ± 59 repetitions) than under normoxic conditions (114 ± 40 repetitions). The root mean square amplitude of EMG and oxygenated hemoglobin concentration for the last five repetitions under normoxic conditions were greater than those under hyperoxic conditions (P = 0.015 and P = 0.003, respectively). The percent change in the maximum number of repetitions between hyperoxic and normoxic conditions had significant positive correlations with individual maximal oxygen uptake measured using an incremental cycle ergometer test (r = 0.562, 95% confidence intervals [CI] = 0.213-0.783, P = 0.003), but not with muscle strength (? = -0.124, 95% CI = -0.424-0.170, P = 0.387). The 95% CI for the correlation coefficient between the percent change in the maximum number of repetitions and muscular endurance included 0 (? = 0.284, 95% CI = -0.003-0.565, P = 0.047); this indicated no significant correlation between the two parameters. The results suggest that hyperoxia can acutely enhance dynamic muscular endurance, with delayed elevation of EMG amplitude due to fatigue, and the effects are associated with individual whole-body endurance capacity.
Project description:In this paper, we present 5th generation (5G) millimeter wave (mmWave) wireless communication propagation losses dataset for four Indian major urban cities like Delhi, Mumbai, Kolkata and Chennai based on corresponding weather conditions. Weather effect on mmWave is calculated in terms of mmWave path losses by considering various atmospheric weather conditions. Propagation of mmWave is affected by weather impairments (WIs) and due to that mmWave attenuation takes place and Indian metro cities have variety in weather variations. 5G mmWave propagation attenuation is calculated due to WIs like water vapour, oxygen, rain and fog for frequencies 28 GHz, 37 GHz and 39 GHz. Individual WI effects during the season are calculated and shown suing graphs and tables.
Project description:Patients with minimal hepatic encephalopathy (MHE) show mild cognitive impairment associated with alterations in attentional and executive networks. There are no studies evaluating the relationship between memory in MHE and structural and functional connectivity (FC) changes in the hippocampal system. This study aimed to evaluate verbal learning and long-term memory in cirrhotic patients with (C-MHE) and without MHE (C-NMHE) and healthy controls. We assessed the relationship between alterations in memory and the structural integrity and FC of the hippocampal system. C-MHE patients showed impairments in learning, long-term memory, and recognition, compared to C-NMHE patients and controls. Cirrhotic patients showed reduced fimbria volume compared to controls. Larger volumes in hippocampus subfields were related to better memory performance in C-NMHE patients and controls. C-MHE patients presented lower FC between the L-presubiculum and L-precuneus than C-NMHE patients. Compared to controls, C-MHE patients had reduced FC between L-presubiculum and subiculum seeds and bilateral precuneus, which correlated with cognitive impairment and memory performance. Alterations in the FC of the hippocampal system could contribute to learning and long-term memory impairments in C-MHE patients. This study demonstrates the association between alterations in learning and long-term memory and structural and FC disturbances in hippocampal structures in cirrhotic patients.
Project description:The progression of functional connectivity (FC) patterns from non-hepatic encephalopathy (non-HE) to minimal HE (MHE) is not well known. This resting-state functional magnetic resonance imaging (rs-fMRI) study investigated the evolution of intrinsic FC patterns from non-HE to MHE. A total of 103 cirrhotic patients (MHE, n?=?34 and non-HE, n?=?69) and 103 healthy controls underwent rs-fMRI scanning. Maps of distant and local FC density (dFCD and lFCD, respectively) were compared among MHE, non-HE, and healthy control groups. Decreased lFCD in anterior cingulate cortex, pre- and postcentral gyri, cuneus, lingual gyrus, and putamen was observed in both MHE and non-HE patients relative to controls. There was no difference in lFCD between MHE and non-HE groups. The latter showed decreased dFCD in inferior parietal lobule, cuneus, and medial frontal cortex relative to controls; however, MHE patients showed decreased dFCD in frontal and parietal cortices as well as increased dFCD in thalamus and caudate head relative to control and non-HE groups. Abnormal FCD values in some regions correlated with MHE patients' neuropsychological performance. In conclusion, lFCD and dFCD were perturbed in MHE. Impaired dFCD in regions within the cortico-striato-thalamic circuit may be more closely associated with the development of MHE.
Project description:Patients with hepatitis B virus (HBV)-related cirrhosis (HBV-RC) and minimal hepatic encephalopathy (MHE) exhibit alterations in homotopic inter-hemispheric functional connectivity (FC) and corpus callosum (CC) degeneration. However, the progression of inter-hemispheric dysconnectivity in cirrhotic patients from no MHE (NMHE) to MHE and its association with the progression of diseased-related cognitive impairment remain uncharacterized. We hypothesized that inter-hemispheric dysconnectivity exists in NMHE patients and further deteriorates at the MHE stage, which is associated with performance measured by psychometric hepatic encephalopathy scores (PHES) that can characterize cirrhotic patients with NMHE and MHE. Using inter-hemispheric homotopic FC and CC (and its subfields) volumetric measurements in 31 patients with HBV-RC (17 with NMHE and 14 with MHE) and 37 healthy controls, we verified that MHE patients had significant attenuated inter-hemispheric homotopic FC in the bilateral cuneus, post-central gyrus, inferior parietal lobule, and superior temporal gyms, as well as CC degeneration in total CC, CC2, CC3, and CC4 (each comparison had a corrected P < 0.05). In contrast, NMHE patients had relatively less severe inter-hemispheric homotopic FC and no CC degeneration. In addition, the degeneration of the CC and inter-hemispheric homotopic functional disconnections correlated with poor PHES performances in all cirrhotic patients (NMHE and MHE). Furthermore, impairment of inter-hemispheric homotopic FC partially mediated the association between CC degeneration and worse PHES performance. Notably, a combination of inter-hemispheric homotopic FC and CC volumes had higher discriminative values according to the area under the curve (AUC) score (AUC = 0.908, P < 0.001) to classify patients into MHE or NMHE groups when compared with either alone. Our findings shed light on the progression of inter-hemispheric dysconnectivity in relation to the progression of disease-related cognitive impairment in patients with HBV-RC.
Project description:The fermentation performance of Saccharomyces cerevisiae in the cellulose to ethanol conversion process is largely influenced by the components of pretreated biomass. The insoluble solids in pretreated biomass predominantly constitute cellulose, lignin, and -to a lesser extent- hemicellulose. It is important to understand the effects of water-insoluble solids (WIS) on yeast cell physiology and metabolism for the overall process optimization. In the presence of synthetic lignocellulosic inhibitors, we observed a reduced lag phase and enhanced volumetric ethanol productivity by S. cerevisiae CEN.PK 113-7D when the minimal medium was supplemented with WIS of pretreated birch or spruce and glucose as the carbon source. To investigate the underlying molecular reasons for the effects of WIS, we studied the response of WIS at the proteome level in yeast cells in the presence of acetic acid as an inhibitor. Comparisons were made with cells grown in the presence of acetic acid but without WIS in the medium. Altogether, 729 proteins were detected and quantified, of which 246 proteins were significantly up-regulated and 274 proteins were significantly down-regulated with a fold change?1.2 in the presence of WIS compared to absence of WIS. The cells in the presence of WIS up-regulated several proteins related to cell wall, glycolysis, electron transport chain, oxidative stress response, oxygen and radical detoxification and unfolded protein response; and down-regulated most proteins related to biosynthetic pathways including amino acid, purine, isoprenoid biosynthesis, aminoacyl-tRNA synthetases and pentose phosphate pathway. Overall, the identified differentially regulated proteins may indicate that the likelihood of increased ATP generation in the presence of WIS was used to defend against acetic acid stress at the expense of reduced biomass formation. Although, comparative proteomics of cells with and without WIS in the acetic acid containing medium revealed numerous changes, a direct effect of WIS on cellular physiology remains to be investigated.
Project description:One of the putative functions of the medial olivocochlear (MOC) system is to enhance signal detection in noise. The objective of this study was to elucidate the role of the MOC system in speech perception in noise. In normal-hearing human listeners, we examined (1) the association between magnitude of MOC inhibition and speech-in-noise performance, and (2) the association between MOC inhibition and the amount of contralateral acoustic stimulation (CAS)-induced shift in speech-in-noise acuity. MOC reflex measurements in this study considered critical measurement issues overlooked in past work by: recording relatively low-level, linear click-evoked otoacoustic emissions (CEOAEs), adopting 6 dB signal-to-noise ratio (SNR) criteria, and computing normalized CEOAE differences. We found normalized index to be a stable measure of MOC inhibition (mean = 17.21%). MOC inhibition was not related to speech-in-noise performance measured without CAS. However, CAS in a speech-in-noise task caused an SNRSP enhancement (mean = 2.45 dB), and this improvement in speech-in-noise acuity was directly related to their MOC reflex assayed by CEOAEs. Individuals do not necessarily use the available MOC-unmasking characteristic while listening to speech in noise, or do not utilize unmasking to the extent that can be shown by artificial MOC activation. It may be the case that the MOC is not actually used under natural listening conditions and the higher auditory centers recruit MOC-mediated mechanisms only in specific listening conditions-those conditions remain to be investigated.
Project description:Minimal hepatic encephalopathy (MHE) is associated with cognitive alterations and changes in connectivity. We assessed the relationship of the abnormalities of resting-state functional connectivity (rs-FC) and gray matter (GM) volume with different cognitive alterations and biochemical parameters associated to MHE.Thirty-nine cirrhotic patients (26 without and 13 with MHE) and 24 controls were widely cognitive assessed with a battery of psychometric tests. Atrophy was determined using Voxel-Based Morphometry and rs-FC was assessed by independent component analysis. Receiver operating characteristic (ROC) curves was performed to assess the diagnostic utility of rs-FC and GM reduction for the discrimination of patients with and without MHE. Blood ammonia, cGMP, and levels of pro-inflammatory interleukins were measured.MHE patients showed significant decrease of GM volume and lesser degree of rs-FC in different networks related to attention and executive functions as compared to controls and patients without MHE. There is a progressive reduction in rs-FC in the default mode network with the progression of cognitive impairment. MHE patients showed GM reduction in the right frontal lobe, right insula and right cerebellum compared to patients without MHE. Alterations in GM volume and rs-FC correlated with the scores of different cognitive tests.Decreased cognitive performance is associated by reduced rs-FC and GM atrophy in MHE patients. These changes could have predictive value for detecting MHE.