Effects of handle height and load on the endurance time for simulated demolition tasks

Work ◽  
2021 ◽  
pp. 1-10
Author(s):  
Kai Way Li ◽  
Wenbao Li ◽  
Lu Peng
Keyword(s):  
Muscle Fatigue ◽  
Regression Models ◽  
Perceived Exertion ◽  
Ratings Of Perceived Exertion ◽  
Endurance Time ◽  
Factors Affecting ◽  
The Mean ◽  
Forceful Exertion ◽  
Load Conditions ◽  
Do So

BACKGROUND: Manual demolition tasks are heavy physical demanding tasks which involve forceful exertion of sustained pushing. They result in muscle fatigue which could lead to musculoskeletal disorders. Assessments of maximum endurance time (MET) are essential in understanding the developing of muscle fatigue for these tasks. OBJECTIVE: The objectives of this study were to determine the effects of handle height and load conditions on the MET, and to establish MET models for the simulated demolition tasks. METHODS: Twenty three male participants performed simulated demolition tasks under three loads and three handle heights conditions until they could not do so any longer. Their METs and ratings of perceived exertion were recorded and analyzed. RESULTS: The results showed that both load and handle height were significant (p <  0.0001) factors affecting the MET. Regression models to predict the MET under handle height and load conditions were established. The mean absolute deviations of these models were between 1.91 and 4.84 min. CONCLUSION: The MET models established may be used to estimate the MET which may be adopted in work/rest arrangement for demolition tasks using a handheld demolition hammer.

scholarly journals Strength Decrease, Perceived Physical Exertion and Endurance Time for Backpacking Tasks

2019 ◽  
Vol 16 (7) ◽  
pp. 1296 ◽  
Author(s):  
Kai Way Li ◽  
Jenn Chun Chu ◽  
Ching Chung Chen
Keyword(s):  
Heart Rate ◽  
Material Handling ◽  
Perceived Exertion ◽  
Walking Speed ◽  
Physical Exertion ◽  
Rating Of Perceived Exertion ◽  
Endurance Time ◽  
Manual Material Handling ◽  
Human Participants ◽  
Do So

Manual material handling (MMH) tasks create a burden for workers which could result in musculoskeletal injuries. Assessments of the decrease of muscular strength and the maximum endurance time (MET) for MMH tasks are essential in studying the ergonomic risk of MMH tasks. A backpacking experiment was conducted for measuring the MET for MMH tasks. Human participants carried a load on their back and walked on a treadmill under various load, walking speed, and ramp angle conditions until they coud no longer do so. It was found that the participants were able to walk for approximately 15 min to two hours before they needed to have a pause. Their back and leg strengths declined moderately due to performing the tasks. These tasks resulted in an increase in heart rate and elevated perceived physical exertion. The rating of perceived exertion (RPE)/heart rate ratio in our backpacking tasks was 31% higher than that in the literature, implying the calibration of the RPE may be required for such tasks. A MET model incorporating the fMVC_back, body weight, walking speed, and ramp angle was established. This model may be used to determine the work/rest allowance for backpacking tasks under conditions similar to this study.

scholarly journals Effects of a Ketogenic Diet on Muscle Fatigue in Healthy, Young, Normal-Weight Women: A Randomized Controlled Feeding Trial

Nutrients ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 955 ◽  
Author(s):  
Anna Sjödin ◽  
Fredrik Hellström ◽  
EwaCarin Sehlstedt ◽  
Michael Svensson ◽  
Jonas Burén
Keyword(s):  
Muscle Fatigue ◽  
Mixed Models ◽  
Perceived Exertion ◽  
Daily Life ◽  
Control Diet ◽  
Normal Weight ◽  
Ratings Of Perceived Exertion ◽  
Daily Life Activities ◽  
Low Carbohydrate ◽  
Handgrip Test

Ketogenic low-carbohydrate high-fat (LCHF) diets are increasingly popular in broad sections of the population. The main objective of this study was to evaluate the effects of a non-energy-restricted ketogenic LCHF diet on muscle fatigue in healthy, young, and normal-weight women. Twenty-four women were randomly allocated to a 4-week ketogenic LCHF diet followed by a 4-week control diet (a National Food Agency recommended diet), or the reverse sequence due to the crossover design. Treatment periods were separated by a 15 week washout period. Seventeen women completed the study and were included in the analyses. Treatment effects were evaluated using mixed models. The ketogenic LCHF diet had no effect on grip strength or time to fatigue, measured with handgrip test (day 24–26). However, cycling time to fatigue decreased with almost two minutes (−1.85 min 95% CI:[−2.30;−1.40]; p < 0.001) during incremental cycling (day 25–27), accommodated with higher ratings of perceived exertion using the Borg scale (p < 0.01). Participants’ own diary notes revealed experiences of muscle fatigue during daily life activities, as well as during exercise. We conclude that in young and healthy women, a ketogenic LCHF diet has an unfavorable effect on muscle fatigue and might affect perceived exertion during daily life activities.

Comparison between students and residents on determinants of willingness to separate waste and waste separation behaviour in Zhengzhou, China

2017 ◽  
Vol 35 (9) ◽  
pp. 949-957 ◽  
Author(s):  
Xiaoping Dai ◽  
Yuping Han ◽  
Xiaohong Zhang ◽  
Wei Hu ◽  
Liangji Huang ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Undergraduate Students ◽  
Regression Models ◽  
Binary Logistic Regression ◽  
Education Level ◽  
Factors Affecting ◽  
Logistic Regression Models ◽  
Management Policies ◽  
Waste Separation ◽  
Do So

A better understanding of willingness to separate waste and waste separation behaviour can aid the design and improvement of waste management policies. Based on the intercept questionnaire survey data of undergraduate students and residents in Zhengzhou City of China, this article compared factors affecting the willingness and behaviour of students and residents to participate in waste separation using two binary logistic regression models. Improvement opportunities for waste separation were also discussed. Binary logistic regression results indicate that knowledge of and attitude to waste separation and acceptance of waste education significantly affect the willingness of undergraduate students to separate waste, and demographic factors, such as gender, age, education level, and income, significantly affect the willingness of residents to do so. Presence of waste-specific bins and attitude to waste separation are drivers of waste separation behaviour for both students and residents. Improved education about waste separation and facilities are effective to stimulate waste separation, and charging on unsorted waste may be an effective way to improve it in Zhengzhou.

scholarly journals Do exercisers maximize their pleasure by default? Using prompts to enhance the affective experience of exercise

2019 ◽  
Author(s):  
Zachary Zenko ◽  
Rachel Kahn ◽  
Catherine J. Berman ◽  
Jasmin C. Hutchinson ◽  
Leighton Jones
Keyword(s):  
Heart Rate ◽  
Perceived Exertion ◽  
Exercise Behavior ◽  
Exercise Session ◽  
Affective Experience ◽  
Affective Valence ◽  
Ratings Of Perceived Exertion ◽  
Post Exercise ◽  
Within Subjects ◽  
Do So

Researchers and practitioners are increasingly recognizing the importance of maximizing pleasure during exercise in order to promote exercise behavior. Self-selected intensity exercise can increase pleasure during exercise, but it is not yet known whether participants maximize pleasure during self-selected intensity exercise by default. We hypothesized that prompting participants to maximize pleasure and enjoyment would result in more positive affective valence during (H1) and after (H2) exercise, greater remembered pleasure following exercise (H3), and greater enjoyment of exercise (H4). In this within-subjects experiment, 39 inactive adults completed 2 10-min stationary cycling sessions at a self-selected intensity. During the experimental condition, participants were reminded (five times during the 10-min session) to maximize pleasure and enjoyment, and that they could change the intensity if they wanted. Affective valence, heart rate, and ratings of perceived exertion were measured every 2 minutes during exercise. Affective valence, enjoyment, and remembered pleasure were measured after each exercise session. The control condition was identical, except no reminders were provided. Each hypothesis was supported (p &lt; .05). Prompting participants to maximize their pleasure and enjoyment resulted in increased pleasure as the exercise session progressed. After receiving prompts, participants also reported more positive post-exercise affective valence and rated the session as more pleasant and enjoyable. These results suggest that participants do not maximize pleasure and enjoyment by default (i.e., in the absence of reminders to do so). Researchers can build on these results to determine the mechanisms and whether prompting exercisers to maximize pleasure and enjoyment can promote exercise behavior.

A New Method for Prescribing Exercise: Three-Point Ratings of Perceived Exertion

1996 ◽  
Vol 82 (1) ◽  
pp. 139-146 ◽  
Author(s):  
Christopher C. Dunbar ◽  
Michael I. Kalinski ◽  
Robert J. Robertson
Keyword(s):  
Perceived Exertion ◽  
Exercise Prescription ◽  
Cycle Ergometer ◽  
New Method ◽  
Clinical Settings ◽  
Ratings Of Perceived Exertion ◽  
Graded Exercise Test ◽  
Treadmill Speed ◽  
Graded Exercise ◽  
The Mean

An accurate exercise prescription for ratings of perceived exertion has previously depended on data from a maximal graded exercise test during which RPE was measured. In many clinical settings RPE is not measured; in many fitness settings maximal testing is not feasible. A new method using treadmill speed or power output of a cycle ergometer at an RPE of 13 from a submaximal test which can be used in these situations is described. We evaluated the accuracy of this method at 50%, 60%, 70%, and 85% VO2max. A total of 160 target RPEs were developed using traditional procedures and the new method. No significant differences between RPEs obtained with the two techniques were found. The mean difference was less than one unit of RPE. It appears that the new method is valid for intensities of 50% to 85% VO2max and that data from either the cycle ergometer or the treadmill can be used to prepare exercise prescriptions.

Effects of Post-Hypnotic Suggestions on Muscular Endurance

1975 ◽  
Vol 40 (1) ◽  
pp. 131-139 ◽  
Author(s):  
Ira Albert ◽  
Melvin H. Williams
Keyword(s):  
Heart Rate ◽  
Perceived Exertion ◽  
Endurance Capacity ◽  
Ratings Of Perceived Exertion ◽  
Endurance Time ◽  
Heart Rate Data ◽  
Control Subjects ◽  
Experimental Subjects ◽  
And Control ◽  
Hypnotic Suggestions

This study examined the effects of post-hypnotic suggestions upon maximal endurance capacity, Borg ratings of perceived exertion, and heart rate. Experimental subjects were administered post-hypnotic suggestions to improve or decrease performance, and control subjects were given similar instructions during the awake state. Endurance time could be decreased significantly when the fatigue suggestion was given to experimental subjects, but performance could not be enhanced with the facilitating suggestion. Control subjects showed no significant changes across conditions. The Borg ratings indicated that experimental subjects experienced subjective changes as suggested by the hypnotist. In addition, analysis failed to find any significant differences for the heart-rate data.

The Slope Method for Prescribing Exercise with Ratings of Perceived Exertion (RPE)

1996 ◽  
Vol 83 (1) ◽  
pp. 91-97 ◽  
Author(s):  
Christopher C. Dunbar ◽  
Diego A. Bursztyn
Keyword(s):  
Perceived Exertion ◽  
Maximal Exercise ◽  
Peak Exercise ◽  
Ratings Of Perceived Exertion ◽  
Simple Method ◽  
Graded Exercise Test ◽  
Slope Method ◽  
Graded Exercise ◽  
The Mean ◽  
Using Data

The Borg Ratings of Perceived Exertion scale (RPE) has been shown to be a valuable tool for prescribing exercise; however, use of RPE-based exercise prescriptions in field settings has often been problematic because RPE data derived from maximal exercise testing are needed. We describe a simple method for obtaining target RPEs for exercise training from submaximal exercise data. Target RPEs for 50%, 60%, 70%, and 85% VO2peak exercise intensities obtained using the new method did not differ significantly from those obtained using data from a maximal graded exercise test. The mean difference was less than one RPE unit and was not significant (p<.05). Therefore, the Slope Method appears to be valid for developing RPE-based exercise prescriptions.

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

2022 ◽  
Vol 19 (2) ◽  
pp. 930
Author(s):  
Cannan Yi ◽  
Fan Tang ◽  
Kai-Way Li ◽  
Hong Hu ◽  
Huali Zuo ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Fatigue Test ◽  
Perceived Exertion ◽  
Recovery Test ◽  
Work Related ◽  
Before And After ◽  
Recovery Models ◽  
Human Participants ◽  
Forceful Exertion ◽  
Fatigue Recovery

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.

Sodium Bicarbonate Supplementation Does Not Improve Running Anaerobic Sprint Test Performance in Semiprofessional Adolescent Soccer Players

2020 ◽  
Vol 30 (5) ◽  
pp. 330-337
Author(s):  
Rodrigo dos Santos Guimarães ◽  
Alcides Correa de Morais Junior ◽  
Raquel Machado Schincaglia ◽  
Bryan Saunders ◽  
Gustavo Duarte Pimentel ◽  
...  
Keyword(s):  
Sodium Bicarbonate ◽  
Muscle Fatigue ◽  
Perceived Exertion ◽  
Sprint Performance ◽  
Soccer Players ◽  
Fatigue Index ◽  
Countermovement Jump ◽  
Ratings Of Perceived Exertion ◽  
Double Blind ◽  
Repeated Sprint

Ergogenic strategies have been studied to alleviate muscle fatigue and improve sports performance. Sodium bicarbonate (NaHCO3) has improved repeated sprint performance in adult team-sports players, but the effect for adolescents is unknown. The aim of the present study was to evaluate the effect of NaHCO3 supplementation on repeated sprint performance in semiprofessional adolescent soccer players. In a double-blind, placebo-controlled, crossover trial, 15 male semiprofessional adolescent soccer players (15 ± 1 years; body fat 10.7 ± 1.3%) ingested NaHCO3 or a placebo (sodium chloride) 90 min before performing the running anaerobic sprint test (RAST). A countermovement jump was performed before and after the RAST, and ratings of perceived exertion, blood parameters (potential hydrogen and bicarbonate concentration), and fatigue index were also evaluated. Supplementation with NaHCO3 promoted alkalosis, as demonstrated by the increase from the baseline to preexercise, compared with the placebo (potential hydrogen: +0.07 ± 0.01 vs. −0.00 ± 0.01, p < .001 and bicarbonate: +3.44 ± 0.38 vs. −1.45 ± 0.31 mmol/L, p < .001); however, this change did not translate into an improvement in RAST total time (32.12 ± 0.30 vs. 33.31 ± 0.41 s, p = .553); fatigue index (5.44 ± 0.64 vs. 6.28 ± 0.64 W/s, p = .263); ratings of perceived exertion (7.60 ± 0.33 vs. 7.80 ± 0.10 units, p = .525); countermovement jump pre-RAST (32.21 ± 3.35 vs. 32.05 ± 3.51 cm, p = .383); or countermovement jump post-RAST (31.70 ± 0.78 vs. 32.74 ± 1.11 cm, p = .696). Acute NaHCO3 supplementation did not reduce muscle fatigue or improve RAST performance in semiprofessional adolescent soccer players. More work assessing supplementation in this age group is required to increase understanding in the area.

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