Physical Load Levels Research Articles

Влияние фаз менструального цикла на частоту и характер травм у профессиональных футболисток

As is known, sport is accompanied by a critical level of physical load, which leads to a steady increase in injuries among athletes. However, sex differences in the risk of tendon and ligament injuries have been reported, with the relative risk of anterior cruciate ligament (ACL) rupture being 2 to 6 times higher in young female athletes compared to male athletes. This indicates that sex differences in the biomechanical properties of tendons are significant during the period of life when the sex hormonal profile is noticeably different in women and men. The purpose — to determine the influence of menstrual cycle phases on the frequency and nature of injuries in professional female football players. Material and methods. 31 athletes of the top division women’s youth team were examined, average age 19.6 ± 1.8. The menstrual cycle was divided into 3 phases: follicular phase (phase 1), ovulation (phase 2), luteal phase (phase 3). Injuries during the annual macrocycle were analyzed. All injuries were classified into muscle ones, injuries of the capsular-ligamentous apparatus, and bone injuries. Injury rates and ratios were calculated for the total number for each injury type. Statistical processing of the data was carried out using the statistical software package SPSS (v.18.0). The χ2 test and Fisher’s exact test were used to analyze the data. Differences were considered statistically significant at p < 0.05. Results. Analysis was carried out for 267 cycles and 39 injuries in 31 players during one playing season. 43.6% of the total injuries occurred in the luteal phase, 46.2% in the follicular phase, and 2.6% in the ovulation phase. In the follicular phase of the menstrual cycle, muscle injuries were more often recorded in female athletes — 75.0% of cases, while damage to the capsular-ligamentous apparatus in this phase was detected only in 33.3% (p = 0.003), and bone injuries were recorded in 50.0% (p = 0.037). Thus, muscle injuries in the follicular phase of the menstrual cycle were statistically significantly more common. The incidence rates of capsular-ligamentous injuries (33.3%) and bone injuries (50.0%) were not statistically significantly different (p = 0.147). Conclusion. The most common injuries among young female football players were injuries to the capsular-ligamentous apparatus (48.7%), followed by muscle injuries (30.8%), while injuries to the capsular-ligamentous apparatus were most characteristic of the luteal phase, and muscle injuries predominated in the follicular phase of the menstrual cycle.

Tomato Fruit Quality as Affected by Ergonomic Conditions While Manually Harvested

The harvest phase plays an important role in the whole process of production of tomato fruit. Therefore, it is necessary to ensure a technological process that will not damage biological materials. The harvest phase plays an important role in the whole process. Many growers use special machines for harvesting, but there are fruits and vegetables that should be harvested manually to avoid damaging the surface or parenchyma tissue of the harvested objects. In addition to maintaining the quality of biological materials, work comfort, and ergonomic conditions for pickers should be ensured because inadequate working conditions do not encourage employees to undertake manual work in horticulture. Therefore, there have been shortages of workers on Polish plantations in the past year. Based on manual tomato harvesting, the authors conducted a matched qualitative research study on biological materials and work ergonomics. For this purpose, the Grip System was used to investigate tomato quality by assessing the impact of picking hand pressure (in three different picker’s body positions) on the harvested objects. Simultaneously, for the picker’s ergonomic analysis, a non-invasive surface electromyography method was used to precisely measure changes in muscle motor unit action in the picker’s wrist and lumbar spine while in three characteristic picker’s positions. The tests found that the poorest body position was when the body was deeply inclined and simultaneously twisted. No significant effect was shown of the body position of the tomato picker on the deterioration of the picked fruit quality. However, body positions significantly affect the level of physical load and work comfort.

Thermography as a tool to assess training effects in military working dogs

Military working dogs are exposed to high levels of physical load during their work, although this is not always evident from their behaviour. This workload causes various physiological changes, including variation in the temperature of the affected body parts. In this preliminary study, we investigated whether thermal changes following the daily work routine of military dogs are detectable by infrared thermography (IRT). The experiment was carried out on eight male German and Belgian shepherd patrol guard dogs performing two training activities, obedience and defence. The surface temperature (Ts) of 12 selected body parts on both body sides was measured with the IRT camera 5 min before, 5 min after and 30 min after training. As predicted, there was a greater increase in Ts (mean of all measured body parts) after defence than after obedience, 5 min (by 1.24 vs. 0.60 °C, P < 0.001) and 30 min after activity (by 0.90vs. 0.57 °C, P < 0.01) compared to pre-activity levels. These findings indicate that defence is more physically demanding than obedience activity. Considering the activities separately, obedience increased Ts 5 min after the activity only in the trunk (P < 0.001) but not in the limbs, whereas defence increased it in all measured body parts (P < 0.001). Ts 30 min after obedience decreased to the pre-activity level in parts at trunk, while in distal parts of the limbs Ts remained elevated. The prolonged elevation in Ts of the limbs after both activities indicates heat flow from the core to the periphery as a thermoregulatory mechanism. The current study suggests that IRT may be a useful tool for assessing physical workload in different body parts of dogs.

HEART RATE INDICATORS WITHIN TRAINING EXERCISES OF UKRAINIAN AND CHINESE BADMINTON PLAYERS AGED 10-12 YEARS

We have found the contradiction between the current requirements of competitive activities and insufficient justification of the methodological provisions of various aspects of the training of qualified badminton players, which led to the urgent scientific and practical task. An important aspect of this is the comparison of exercise load data (in terms of heart rate) between Ukrainian and Chinese badminton players in the same age group. Aim: to compare the heart rate of Ukrainian and Chinese badminton players aged 10-12 years within the training exercises. Material &amp; Methods. We have used theoretical analysis and generalisation of scientific and methodological data, pedagogical observations of heart rate during training exercises of badminton players aged 10-12 years (the first zone provided for indicators within 124 bpm, the 2 – 125-145 bpm, the 3 – 146-166 bpm, the 4 – 167-187 bpm, and the 5 – more than 188 bpm), methods of mathematical statistics. During 2019, training exercises with the participation of 102 Ukrainian and 112 Chinese badminton players aged 10-12 were analysed. Results. Chinese athletes perform more intense loads, which are characterised by increased heart rate indicators and reflected in the share of those being in the fifth heart rate zone. At the same time, Ukrainian badminton players achieve a significantly higher (p≤0.01) average heart rate level by compensating for the use of marginal and near-marginal intensity in exercises, by increasing the amount of exercise performed in the third and partially second heart rate zones. Significant predominance (p≤0.01) of Chinese badminton players was found in the total duration of training sessions (20.03%), absolute and relative values of being in the first (59.04−87.12%) and the fifth (230−297%) heart rate zones, the number of moving to the fifth heart rate zone (173.02%). Ukrainian badminton players significantly (p≤0.05) outperform their Chinese peers in the average heart rate indicator of the athlete in training (2.72%), the absolute values of being in the second heart rate zone (16.91%), absolute and relative values of being in the third heart rate zone (16.95-31.11%). Conclusions. During the preparation of Chinese athletes, more attention is paid to the systematic and gradual increase in physical load (in terms of volume and intensity) compared to the Ukrainian peers. Based on the identified structure, we assume that moving from one level of physical load to another one takes place according to the alternation of loads of different intensity and volume.

Сравнительный анализ физического развития школьников и детей, профессионально занимающихся плаванием

Health of children and adolescents is an essential criterion of well-being of the society. Monitoring of health among children is impossible without assessment of physical development of children and adolescents. Individual-based analysis of anthropometric characteristics is required to develop personalized preventive activities. Considering different levels of physical load of schoolchildren in case of a disturbed nutritional status, an approach to body mass constituent study that deviates from the normal values requires examination. The study purpose was to assess physical development and component composition in schoolchildren during a medical examination and in children involved in classic swimming at a sports club in the city of Samara. The study object involved children studying at a general educational institution and not engaged in any sports sections (first group), and children involved in classic swimming at a sports club in Samara (second group. Significant differences in basic values of body composition were found during the conducted study of physical development and component composition of schoolchildren who do not go in for sports and junior athletes.

Physiological Workload Analysis on the Use of Face Masks during Physical Activities

During the COVID-19 pandemic people are required to limit outside activities and keep following social distancing protocol. However, several studies have reported that indoor exercises have a greater risk toward COVID-19 virus infection. Therefore, wearing a mask during light to moderate intensity of outdoor physical activity is still recommended. We conduct an experiment to analyze physiological ergonomics aspect, whether people wearing different type of masks during physical activities and distraction of music would affect heart rate. Analysis of the average heart rate data was carried out using the calculation of VO2max and Energy Expenditure to determine the workload level of the four scenarios of treatment combination. The result shows a heavy level of physical load on the use of surgical mask with distraction of music and moderate level of physical load on the use of surgical without distraction of music.

The Preventive Role of Physical Activity in Systemic Sclerosis: A Cross-Sectional Study on the Correlation with Clinical Parameters and Disease Progression.

Although exercise is associated with improved health in many medical conditions, little is known about the possible influences of physical activity (PA) habits pre- and post- a diagnosis of systemic sclerosis (SSc) on disease activity and progression. This cross-sectional study assessed, for the first time, self-reported pre- and post-diagnostic PA levels with the aim to verify if changes in these levels were correlated with demographic/anthropometric data (e.g., weight, height, gender, age, BMI), disease duration, diagnostic/clinical parameters (e.g., skin involvement, pulmonary hemodynamic/echocardiographic data, disease activity) related to disease activity and progression, and quality of life in a population-based sample of patients with SSc. Adult participants (n = 34, age 56.6 ± 13.3 years) with SSc (limited cutaneous SSc, lcSSc, n = 20; diffuse cutaneous SSc, dcSSc, n = 9; sine scleroderma SSc, n = 5) were enrolled at the Division of Rheumatology and Clinical Immunology of the Humanitas Research Hospital. All medical data were recorded during periodic clinical visits by a rheumatologist. Moreover, all subjects included in this study completed extensive questionnaires to evaluate their health-related quality of life (HRQOL), and others related to health-related physical activity performed before (PRE) and after (POST) the diagnosis of disease. The linear regression analysis has shown that either a high Sport_index or Leisure_index in the PRE-diagnostic period was correlated with lower disease duration in dcSSc patients. Physical load during sport activity and leisure time accounted for ~61.1% and ~52.6% of the individual variation in disease duration, respectively. In lcSSc patients, a high PRE value related to physical load during sporting activities was correlated with a low pulmonary artery systolic pressure (sPAP) and the POST value of the Work_index was positively correlated with the left ventricular ejection fraction (LVEF), and negatively with creatine kinase levels (CK). Interestingly, the univariate analysis showed that Work_index accounts for ~29.4% of the variance in LVEF. Our analysis clearly reinforces the concept that high levels of physical load may play a role in primary prevention—delaying the onset of the disease in those subjects with a family history of SSc—as well as in secondary prevention, improving SSc management through a positive impact on different clinical parameters of the disease. However, it remains a priority to identify a customized physical load in order to minimize the possible negative effects of PA.

Association between occupational physical activity and quantitative bone ultrasound in sawmill workers

A small number of studies have examined the relationship between bone health and level of physical load. We explored the effect of occupational physical activity on skeletal status in younger sawmill workers using ultrasonic indices of bone density. In a cross-sectional study, we measured bone density with quantitative ultrasound (QUS) in 128 sawmill workers (89 men and 39 women), mean age 39.1 +/- 10.8 years. Back strength was measured by dynamometry. Information on occupational and leisure physical activity, joint pain, education and smoking were obtained with the questionnaire. All QUS bone parameters and back strength were significantly higher in men than in women. A T score for quantitative ultrasound index (QUI) of − 2.2 or lower was found only in two men and one women. QUI did not significantly differ based on presence of parameters of physical occupational activity (carrying loads exceeding 5 kg, repetitive movements, physical exertion while working and non-sitting position at work). When controlling for age, gender and body mass index, participants with higher smoking index had significantly lower QUI (p=0.004). Physical workload was not significantly associated with QUI. In our working population, some lifestyle habits, such as smoking, had a greater impact on bone health than physical occupational activity.

Biomechanical load during patient transfer with assistive devices: Cross-sectional study

This study utilised a cross-sectional design to perform measurements of muscle activity as well as forward - and lateral trunk inclination angle during a full workday among 52 female healthcare workers from 16 different departments at five Danish hospitals. Using linear mixed models, the 95th percentile ranks of the normalised root mean square (nRMS) values were analysed for the different types of assistive devices. Compared to no assistive device (mean nRMS 27.9%, 95% CI 24.8%–31.0%), the use of intelligent beds (23.9%, CI 20.2%–27.6%) and ceiling-lifts (24.0%, CI 20.3%–27.7%) led to lower erector spinae nRMS values across all types of patient transfers. Conversely, the use of bedsheets (30.6%, CI 27.1%–34.2%), sliding-sheets (30.3%, CI 26.8%–33.9%) and sliding-boards (33.5%, CI 29.5%–37.6%) were associated with higher levels of erector spinae muscle activity.Consistent use of ceiling-lifts and intelligent beds reduces the physical workload and may thereby decrease the risk of musculoskeletal disorders among healthcare workers. Practioner Summary: Frequent patient transfer is associated with an increased risk of back pain and injury among healthcare workers. This analysis compares the level of physical load during patient transfer with commonly used assistive devices. The results show that use of the ceiling-lift and intelligent bed is associated with relatively low physical load during patient transfer. Abbreviations: RMS: root mean square; nRMS: normalized root mean square; EMG: electromyography; MSD: musculoskeletal disorder; LBP: low-back pain; VAS: visual analogue scale; MVC: maximal voluntary contraction

Deep learning-based classification of work-related physical load levels in construction

Work-related musculoskeletal disorders (WMSDs) are the leading cause of the nonfatal injuries for construction workers, and a worker’s overexertion is a major source of such WMSDs. Pushing, pulling, and carrying movements—which are all activities largely associated with physical loads—account for 35% of WMSDs. However, most previous studies have focused on the identification of non-ergonomic postures, and there has been limited effort expended on measuring a worker’s exposures to the physical loads caused by materials or tools during construction tasks. With the advantage of using a wearable inertial measurement sensor to monitor a worker’s bodily movements, this study investigates the feasibility of identifying various physical loading conditions by analyzing a worker’s lower body movements. In the experiment with laboratory settings, workers performed a load carrying task by moving concrete bricks. A bidirectional long short-term memory algorithm is employed to classify physical load levels; this approach achieved 74.6 to 98.6% accuracy and 0.59 to 0.99 F-score in classification. The results demonstrate the feasibility of the proposed approach in identifying the states of physical loads. The findings of this study contribute to the literature on classifying ergonomically at-risk workers and on preventing WMSDs in high physical demand occupations, thereby helping enhance the health and safety of the construction workplace.

Perceptions of effort sensations in children at varying stages of cognitive development

Most research on perceived effort in children has emanated from a physiological perspective. The purpose of this study was to delineate how children at two different levels of cognitive development perceive three effort sensations (e.g. breathing, exertion, and determination) during a physically incremental task. Participants (n = 50) for this study were recruited from two general age cohorts: 9 years of age (representing the concrete operational stage of cognitive development) and 13 years of age (representing the formal operational stage of cognitive development). Participants performed a stepping task under two physical load levels (0% and +20% of body weight). Dimensions of perceived effort sensations were measured at 30s intervals throughout the exercise. Both, concrete and formal operation cohorts, distinguished the effort sensations similarly across the duration of the exertive task and the two physical loads. Perceived exertion and breathing sensations increased linearly with effort intensity in both cohorts. Determination ratings did not remain stable over time for children in either stage of cognitive development, indicating that children may perceive this dimension differently than adults. The findings indicate that concrete and formal cognitive developmental stages do not pose any evaluative constrains on perceived exertion in young children and the motivational dimension of effort should be further studied in these cohorts.

New easy to use postural assessment method through visual management

Earlier studies have demonstrated the strong relationships between manual assembly work with a high repetition level and the presence of repetitive strain injuries (RSI) or repetitive motion illnesses (RMI). Moreover, recent works have also correlated the high physical load level in assembly lines with an increased number of quality defects in finished products. Thus, the ergo-quality level of a manual workstation needs to be carefully monitored not only to respond to the legislation but first of all to ensure a high system productivity level in the medium-term perspective. The objective of this study was to develop and test a new easy-to-use postural assessment tool and its performance in a car component assembly system. The results show the promising potential of the methodology particularly when compared with the well-known OCRA method.

Assembly failures and action cost in relation to complexity level and assembly ergonomics in manual assembly (part 2)

Earlier studies have demonstrated strong relationships between manual assembly at high physical load levels and increased amounts of quality defects compared to assembly at low physical load levels. A recent Swedish interview study of engineers in design and manufacturing engineering indicated that assembly complexity factors are of additional importance for the assembly quality. The objective of this study was therefore to examine the significance of high and low complexity criteria and the relationships between assembly ergonomics and assembly complexity and quality failures by analyzing manual assembly tasks in car manufacturing. In total, 47 000 cars were analyzed and the results showed several significant correlations between assembly ergonomics and assembly complexity, assembly time, failures and action costs. The action costs for high complexity tasks were 22.4 times increased per task per car compared to low complexity tasks. Relevance to industryAssembly ergonomics and assembly complexity factors interact. Both should be proactively considered in order to keep assembly-related failures and action costs as low as possible.

Application of the Cube Model for Biomechanical Exposure Assessment of Combined Manual Material Handling Tasks in a Manufacturing Plant in India

OCCUPATIONAL APPLICATIONS In this study, a biomechanical exposure assessment methodology for combined manual material handling tasks is devised using the “cube” model approach (including time, force, and posture), specifically by modifying the model dimensions. The resulting modified cube model aims to facilitate biomechanical exposure assessment of manual material handling tasks, particularly for industrial conditions where a chain of combined manual material handling activities is carried out across a wide geographical area, and where no direct measurements of biomechanical exposures are available. This methodology can help in prioritizing high-exertion manual material handling tasks for subsequent ergonomic analysis and redesign.TECHNICAL ABSTRACT Background: Biomechanical exposure measurement is difficult for combined manual material handling tasks in field settings and/or resource-constrained environments. “Cube” models—integrating time, force, and posture—have been used previously, but existing models have not been applied to manual material handling tasks. Purpose: The objective of this study was to develop a revised cube model as a biomechanical exposure assessment tool for combined manual material handling tasks. Methods: The study was conducted in a bearing manufacturing plant in India. First, a work-sampling approach was used to observe all manual material handling tasks and record relevant details. Then, two modified models—cube model 1 and cube model 2—were developed by modifying the existing cube model dimensions; physical load intensity and overall physical load were calculated using these two models under a novel cumulative exposure measurement framework. Decision criteria for cumulative cube score were formulated to classify manual material handling tasks under three physical load levels (i.e., low, medium, and high). Finally, cube model assessments were compared with biomechanical assessments of all manual material handling tasks. Results: Attribute agreement (overall correct classification) values for the existing cube model, cube model 1, and cube model 2 were 39%, 61%, and 69%, respectively, indicating better performance for cube model 2. Spearman rank order correlations comparing cumulative cube scores with cumulative biomechanical measures ranged from 0.73 to 0.94, which is considered to be high. Conclusions: The study presents a methodology to assess biomechanical exposures for combined manual material handling tasks by modifying the existing cube model. A cumulative dose concept as applied in biomechanical analysis was used in the study. The cumulative cube score is proposed as a proxy to indicate the overall biomechanical exposure during a combined manual material handling task. Cumulative cube scores gave good agreement between cube model 2 evaluations and biomechanical evaluations, supporting its applicability for evaluating manual material handling tasks.

A model for calculation of the costs of poor assembly ergonomics (part 1)

In product development there are many design requirements to meet and often tough project budgets to keep. Requirements that are considered not profitable will often be neglected, which affects assembly ergonomics. The objective of this study was to develop a calculation model for application in practice that enables calculation of costs of poor assembly quality related to assembly ergonomic conditions. The model is meant to be used by engineers and stakeholders in the design or redesign of manual assembly solutions. For that purpose, manual assembly tasks of 47061 cars at high, moderate and low physical load levels were analyzed with respect to assembly-related quality errors and corresponding action costs during production and on the market. The results showed that ergonomics high risk issues had 5–8 times as many quality errors as low risk issues and the earlier these were found the less were the action costs. The action costs for errors that were discovered late in assembly were 9.2 times more costly compared to early repair of errors in the factory. The action costs for quality errors that were found and corrected on the market were further 12.2 times more expensive to correct compared to actions taken in the factory. Examples are shown of how to apply the calculation model that was developed based on the obtained quality data. Relevance to industryBoth ergonomics and quality issues can be proactively solved through simultaneous risk assessment in early product development and hereby late reactive action costs can be greatly reduced.

Psychophysiological responses to different levels of cognitive and physical workload in haptic interaction

SUMMARYPsychophysiological measurements, which serve as objective indicators of psychological state, have recently been introduced into human–robot interaction. However, their usefulness in haptic interaction is uncertain, since they are influenced by physical workload. This study analyses psychophysiological responses to a haptic task with three different difficulty levels and two different levels of physical load. Four physiological responses were recorded: heart rate, skin conductance, respiratory rate and skin temperature. Results show that mean respiratory rate, respiratory rate variability and skin temperature show significant differences between difficulty levels regardless of physical load and can be used to estimate cognitive workload in haptic interaction.

Predicting the long term course of low back pain and its consequences for sickness absence and associated work disability

Background: Low back pain is characterised by a dynamic pattern of episodes and recovery but little is known about the long term course of back pain due to lack of...

Work Characteristics and Upper Extremity Disorders in Female Dental Health Workers

Many dental health workers suffer from musculoskeletal disorders in the upper extremities. In addition to ergonomic factors, psychosocial work characteristics have been linked to musculoskeletal disorders. The present cross-sectional study aimed at investigating how musculoskeletal disorders in the upper extremities (UED) and occupational position are related to work characteristics and general health problems in female dental health workers. Questionnaire data from dentists, dental hygienists and dental nurses (N=945) showed that 81% reported UED. Multivariate analysis of variance showed that dentists reported the highest levels of physical load and fatigue whereas dental nurses reported the lowest levels of influence at work. Irrespective of position, those with UED considered their physical and psychosocial work environment and their own health to be significantly poorer than did those without UED. A hierarchical multiple regression showed that the physical load of dentistry was most strongly related to UED. Despite improvements to the ergonomics and physical work environment of dentistry, it is concluded that female dental health workers are still at high risk of developing UED.

Increasing the degree of automation in a production system: Consequences for the physical workload

In spite of the continuous development of production systems work-related musculoskeletal disorders is still a large problem. One reason might be the difficulties in quantifying the ergonomic effects of interventions. In this paper ergonomic consequences of technical and organisational changes were quantified in a plant for producing slats for parquet flooring. Muscle activity, work postures and movements were assessed for neck/shoulders and upper limb by direct technical measurements at three generations of production lines. The physical workload for 31 operators at the manual, semi-automated and automated line was derived based on all existing work tasks. The work was characterised by moderate muscular loads, the 50th percentiles being 1.2–3.8%MVE for the neck/shoulder muscles, high repetitiveness and constant movements of the hands and a high prevalence of neck/shoulder disorders. There were statistically significant differences considering exposure levels between the work tasks within each line as well as between the lines. The semi-automated line implied reduced muscular load for all muscles registered but more constrained work postures. The automated line, on the other hand, required higher skills, offered less constrained postures, lower loads and repetitiveness for the hands as well as frequent changes between different physical load levels. Relevance to industry When designing or redesigning production systems, technical solutions are often used to obtain ‘beneficial’ ergonomic conditions, implying a strive for low physical workloads. However, there is a risk that this might lead to more constrained physical activities. Possibilities for job enlargement must be thoroughly utilised.

The impact of working technique on physical loads—an exposure profile among newspaper editors

The aim of this study was to investigate the possible associations between working technique, sex, symptoms and level of physical load in VDU-work. A study group of 32 employees in the editing department of a daily newspaper answered a questionnaire, about physical working conditions and symptoms from the neck and the upper extremities. Muscular load, wrist positions and computer mouse forces were measured. Working technique was assessed from an observation protocol for computer work. In addition ratings of perceived exertion and overall comfort were collected. The results showed that subjects classified as having a good working technique worked with less muscular load in the forearm (extensor carpi ulnaris p=0.03) and in the trapezius muscle on the mouse operating side (p=0.02) compared to subjects classified as having a poor working technique. Moreover there were no differences in gap frequency (number of episodes when muscle activity is below 2.5% of a reference contraction) or muscular rest (total duration of gaps) between the two working technique groups. Women in this study used more force (mean force p=0.006, peak force p=0.02) expressed as % MVC than the men when operating the computer mouse. No major differences were shown in muscular load, wrist postures, perceived exertion or perceived comfort between men and women or between cases and symptom free subjects. In conclusion a good working technique was associated with reduced muscular load in the forearm muscles and in the trapezius muscle on the mouse operating side. Moreover women used more force (mean force and peak force) than men when operating the click button (left button) of the computer mouse.