Modeling and Validation of Fatigue and Recovery of Muscles for Manual Demolition Tasks

Manual demolition tasks are heavy, physically demanding tasks that could cause muscle fatigue accumulation and lead to work-related musculoskeletal disorders (WMSDs). Fatigue and recovery models of muscles are essential in understanding the accumulation and the reduction in muscle fatigue for forceful exertion tasks. This study aims to explore the onset of muscle fatigue under different work/rest arrangements during manual demolition tasks and the offset of fatigue over time after the tasks were performed. An experiment, including a muscle fatigue test and a muscle fatigue recovery test, was performed. Seventeen male adults without experience in demolition hammer operation were recruited as human participants. Two demolition hammers (large and small) were adopted. The push force was either 20 or 40 N. The posture mimicked that of a demolition task on a wall. In the muscle fatigue test, the muscle strength (MS) before and after the demolition task, maximum endurance time (MET), and the Borg category-ratio-10 (CR-10) ratings of perceived exertion after the demolition task were measured. In the muscle fatigue recovery test, MS and CR-10 at times 1, 2, 3, 4, 5, and 6 min were recorded. Statistical analyses were performed to explore the influence of push force and the weight of the tool on MS, MET, and CR-10. Both muscle fatigue models and muscle fatigue recovery models were established and validated. The results showed that push force affected MET significantly (p < 0.05). The weight of the tool was significant (p < 0.05) only on the CR-10 rating after the first pull. During the muscle fatigue recovery test, the MS increase and the CR-10 decrease were both significant (p < 0.05) after one or more breaks. Models of MET and MS prediction were established to assess muscle fatigue recovery, respectively. The absolute (AD) and relative (RD) deviations of the MET model were 1.83 (±1.94) min and 34.80 (±31.48)%, respectively. The AD and RD of the MS model were 1.39 (±0.81) N and 1.9 (±1.2)%, respectively. These models are capable of predicting the progress and recovery of muscle fatigue, respectively, and may be adopted in work/rest arrangements for novice workers performing demolition tasks.

Relationship between body composition, Yo-Yo intermittent recovery test and vertical jump test in elite young soccer players

Objective: The aim of this study is to find out the relationships among body composition, Yo-Yo intermittent recovery (IR) test and vertical jump test in elite young soccer players. Material and Methods: Eighteen healthy young male soccer players (Age: 16.5±0.3 years, height: 178.0±5.9 cm, body weight: 65.9±7.9kg,) voluntarily participated in the study. Total and regional body composition parameters of the soccer players were examined through a dual-energy x-ray absorptiometry (DEXA) method. Vertical jump performance tests were squat jump (SJ) and active jump (AJ), and endurance performances were determined by the Yo-Yo intermittent recovery level 1 test (Yo-Yo IR1). Relationships among body composition, Yo-Yo intermittent recovery test and vertical jump test were analyzed with Pearson Correlation coefficient. Significance level was taken as ≤0.05. Results: A statistically significant negative correlation was found between squat jump and countermovement jump (r=-0.588, r=-0.573, p<0.05), and the leg fat rate. However, there were no statistically significant relationship among squat jump, Yo-Yo IR1 and countermovement jump and other whole/regional body composition (p>0.05). Conclusion: Changes in body composition are important issues for the physical performance level of young soccer players, as local excess body fat may cause deterioration, especially in jumping performance.

The Team Handball Game-Based Performance Test Is Better than the Yo-Yo Intermittent Recovery Test to Measure Match-Related Activities in Female Adult Top-Elite Field Team Handball Players

In team handball, suitable tests determining the match-related physical performance are essential for the planning of optimal physical training regimens. Thus, the aims of the present study were (a) to determine the relationships between the physical and physiological test results from a team handball game-based performance test (GBPT), the Yo-Yo intermittent recovery test, level 1 (Yo-Yo IR1 test) and a separate linear 30-m single sprint performance test (SSPT) in female adult top-elite field team handball players, in order to establish the significance (validity) of tests for measuring relevant elements for team handball match-play; and (b) to compare and evaluate the results from the aforementioned tests for the same players in relation to the different playing positions. Twenty-three female adult top-elite field team handball players from the Danish Premier Female Team Handball League performed the GBPT, the Yo-Yo IR1 test and the 30-m SSPT test on separate days. As main findings, significant correlations between the GBPT and the Yo-Yo IR1 test in about 1/3 of the variables were found, indicating that the Yo-Yo IR1 test is reflecting most of the locomotive match activities in female adult top-elite team handball. However, the Yo-Yo IR1 test results were not correlated to the GBPT in any of the match-related activities in the team handball GBPT that included technical playing actions such as tackles, passes, jumping and shooting during specialized movements in offence and defence. Overall, the results revealed that the GBPT is better than the Yo-Yo IR1 test to evaluate female adult top-elite field team handball players’ ability to perform physical match-related activities including both locomotive and technical playing actions executed as during competitive match-play. Similar to the Yo-Yo IR1 test, the 30-m SSPT was not correlated to any of the team handball GBPT activities, which included technical playing actions. These data suggest that the SSPT only to a certain extent can measure the individual sprint capacity of elite team handball players. In addition, unexpectedly no significant differences between the various playing positions were found neither for the GBPT, the SSPT nor the Yo-Yo IR1 test. However, several effects sizes indicated that the lack of positional differences primarily was due to the relatively small sample size in each playing position and the composition of the specific group of players. In conclusion, this study clearly indicated that team handball specific physical performance, as measured by the GBPT, and general physical performance, as measured by the Yo-Yo IR1 test and the 30-m SSPT, are different components. This must be taken in consideration when using physical test results for the planning of optimal physical training regimens in elite team handball.

Content Validity of Drug Addiction Recovery Test Instruments Using Content Validity Ratio (CVR) Method

Recovery is related to control addiction problems among drug addicts based on context environment in Malaysia. This research, to identify several aspects that have relationship with addiction recovery among Malaysian drug addicts specifically. Although there are several measurement instruments that have been developed to assess drug addiction recovery, a good validity instruments are still lacking and limited. In this regard, this study aimed to test content validity of Drug Addiction Recovery Test (DART) instruments specifically among 123 treated addicts in Besut Cure and Care Rehabilitation Centre (CCRC) using the content validation Ratio (CVR) method to ensure that measurement instruments are appropriate for use in local contexts and cultures. Eight experts selected according to experience they are in a particular field of research. The experts made up of UniSZA, UMT and UPSI. The instrument validation process involved 80 items from four components. The previous study found that the instrument had good validity with the minimum level of CVR value (N=8, CVR = 0.75). A total of 68 items were identified to be retained while the other 12 items had values below 0.75 rated refund and purified. This study found that the instrument is appropriate and relevant and has the potential to be a good instrument for measuring addiction recovery among drug addicts. It is proposed that pilot studies be conducted, and the data should be analysed using more in-depth statistical analysis such as factor analysis to obtain more detailed information about the items. Keywords: Content validity, Addiction recovery, Drug addict, Expert

Development of derivative spectrophotometric method for simultaneous determination of pyrazinamide and rifampicin in cubosome formulation

The ultraviolet spectrophotometry analysis for quantitative assay of drugs is a method accurate, sensitive, selective and reproductive with the advantage of being a simple and less expensive method. In this study, a derivative ultraviolet spectrophotometric method was developed for simultaneous determination of pyrazinamide (PYZ) and rifampicin (RIF). The spectrophotometric method was evaluated according to validation guidelines for specificity, linearity, limits of detection and quantification, precision, accuracy and robustness. The first-derivative spectra were obtained and by the zerocrossing point, the wavelength 247 nm and 365 nm were selected for PYZ and RIF quantification, respectively. No interference from cubosome excipients was detected in the proposed method. The results demonstrated linearity in a range of 4.0 – 12.0 µg/mL with an adequate correlation coefficient for both drugs. The intra and inter-day precision results (RSD < 5%) indicated the reproducibility of the method. The accuracy data showed satisfactory results (RSD < 5%) from recovery test. In addition, the robustness results showed that the PYZ and RIF content were unaffected by the solvent alteration of methanol to methanol:water (99:1, v/v). The derivative ultraviolet spectrophotometric method proved to be an excellent strategy for simultaneous determination of PYZ and RIF.

Assessment of of automated pressurized liquid extraction method followed by enzyme-linked immunosorbent assay for monitoring air-born dioxins

An automated procedure of sample preparation using pressurized liquid extraction (PLE) was developed for subsequent analysis by enzyme-linked immunosorbent assay (ELISA) for dioxins detection in ambient air samples collected from Burlington Ontario. Ambient air samples were collected from particle-phase using glass fibre filters (GFF) and from gas-phase using polyurethane foam from November 2014 to February 2015. The PLE extracts were cleaned up with acid silica followed by carbon mini-column. The average concentration of dioxins in particle phase was found to be 9.96±4.5 fgTEQ/m3 (n=10). This empirical finding is in agreement with high resolution gas chromatography –high resolution mass spectrometry (GC-MS) mean result of 10.04±2.9 fgTEQ/m3 (n=5). However, due to the limited sample size correlation between the two methods cannot be statistically established. The higher concentration of dioxins in Burlington, a city with heavy industry, was expected comparing the finding from previous study for downtown metropolitan Toronto (7.6 ± 2.0 fg BEQ/m3). Development of this method relied on calibration test, recovery test and Certified Reference Material (CRM) evaluation. Calibration test was successful in terms of developing standard curve with results within one standard deviation of the mean concentration of calibration standards. ELISA result on CRM was acceptable. Recovery test on extended toluene evaporation to half an hour or higher increased the recovery from 45% to an average of 82.4% for high concentrations and 89% for medium concentration of dioxins spike. The results of this study illustrate that PLE / ELISA can substitute for GC-HRMS as a cost effective screening tool to determine the dioxins concentration in ambient air.

Assessment of of automated pressurized liquid extraction method followed by enzyme-linked immunosorbent assay for monitoring air-born dioxins

An automated procedure of sample preparation using pressurized liquid extraction (PLE) was developed for subsequent analysis by enzyme-linked immunosorbent assay (ELISA) for dioxins detection in ambient air samples collected from Burlington Ontario. Ambient air samples were collected from particle-phase using glass fibre filters (GFF) and from gas-phase using polyurethane foam from November 2014 to February 2015. The PLE extracts were cleaned up with acid silica followed by carbon mini-column. The average concentration of dioxins in particle phase was found to be 9.96±4.5 fgTEQ/m3 (n=10). This empirical finding is in agreement with high resolution gas chromatography –high resolution mass spectrometry (GC-MS) mean result of 10.04±2.9 fgTEQ/m3 (n=5). However, due to the limited sample size correlation between the two methods cannot be statistically established. The higher concentration of dioxins in Burlington, a city with heavy industry, was expected comparing the finding from previous study for downtown metropolitan Toronto (7.6 ± 2.0 fg BEQ/m3). Development of this method relied on calibration test, recovery test and Certified Reference Material (CRM) evaluation. Calibration test was successful in terms of developing standard curve with results within one standard deviation of the mean concentration of calibration standards. ELISA result on CRM was acceptable. Recovery test on extended toluene evaporation to half an hour or higher increased the recovery from 45% to an average of 82.4% for high concentrations and 89% for medium concentration of dioxins spike. The results of this study illustrate that PLE / ELISA can substitute for GC-HRMS as a cost effective screening tool to determine the dioxins concentration in ambient air.