Chronic Polyhydramnios: A Medical Entity Which Could Be a Model of Muscle Development in Decreased Mechanical Loading Condition

Polyhydramnios is a condition related to an excessive accumulation of amniotic fluid in the third trimester of pregnancy and it can be acute and chronic depending on the duration. Published data suggest that during muscle development, in the stage of late histochemical differentiation decreased mechanical loading cause decreased expression of myosin heavy chain (MHC) type 1 leading to slow-to-fast transition. In the case of chronic polyhydramnios, histochemical muscle differentiation could be affected as a consequence of permanent decreased physical loading. Most affected would be muscles which are the most active i.e., spine extensor muscles and muscles of legs. Long-lasting decreased mechanical loading on muscle should cause decreased expression of MHC type 1 leading to slow-to-fast transition, decreased number of muscle fiber type I especially in extensor muscles of spine and legs. Additionally, because MHC type 1 is present in all skeletal muscles it could lead to various degrees of hypotrophy depending on constituting a percentage of MHC type 1 in affected muscles. These changes in the case of preexisting muscle disorders have the potential to deteriorate the muscle condition additionally. Given these facts, idiopathic chronic polyhydramnios is a rare opportunity to study the influence of reduced physical loading on muscle development in the human fetus. Also, it could be a medical entity to examine the influence of micro- and hypogravity conditions on the development of the fetal muscular system during the last trimester of gestation.

Fitness Of West Kalimantan Martial Arts PON Athletes: Independent Limited Exercise During Covid-19

Fitness is the ability and ability of the body to adjust to physical loading without significant fatigue. Physical activity is one way to create endurance and a fit body. Good endurance is very much needed by martial arts athletes, especially during this Covid-19 period, both in the daily training process and when competing. This study aims to analyze and determine the fitness level of athletes in martial arts during limited independent training, using a survey method in the form of descriptive research. The population is PON 2021 West Kalimantan athletes in martial sports, using a total sampling technique where the sample used is all athletes PON XX 2021 West Kalimantan in martial arts, totaling 12 athletes. The results of the fitness item test found that the average endurance ability was 42.69 (very poor category), average speed was 5.04 (poor category), average agility was 14.38 (enough category), average balance was 14.38 (enough category), average flexibility 18.59 (very good category). The conclusion from this study still needs special attention, especially in fixing some of the supporting elements of fitness that are still not in good condition, with a poor level of fitness it will have an impact on health, especially during the Covid-19 period so that it can affect the athlete's performance.

Cognitive Ergonomics of Assembly Work from a Job Demands–Resources Perspective: Three Qualitative Case Studies

In manufacturing companies, cognitive processing is required from assembly workers to perform correct and timely assembly of complex products, often with varied specifications and high quality demands. This paper explores assembly operators’ perceptions of cognitive/mental workload to provide a holistic understanding of the work conditions that affect cognitive demands and performance. While the physical loading aspects of assembly work are well known, most empirical literature dealing with cognitive/mental loading in manufacturing tends to examine a few particular aspects, rather than address the issue with a holistic system view. This semi-structured interview study, involving 50 industrial assembly operators from three Swedish companies, explores how assemblers perceive that their cognitive performance and well-being is influenced by a wide variety of factors within the context of mechanical product assembly. The interview transcripts were analysed using a priori coding, followed by bottom-up Thematic Analysis. The results indicate that a variety of systemic effects on assemblers’ cognitive performance can be classified as job demands or resources. Quite often, the absence of a resource mirrors a related demand, and “good assembly conditions”, as described by the interviewees, often re-frame demands as desirable challenges that foster motivation and positive feelings towards the work. The identified demands and resources stem from task design, timing, physical loading, intrinsic and extrinsic motivators, social teamwork and the product’s “interface” design. Despite organisational differences and conditions between the three companies that took part in the study, the results are largely consistent.

Exploring the Interaction Between Head-Supported Mass, Posture, and Visual Stress on Neck Muscle Activation

Objective Assess neck muscle activity for varying interactions between helmet, posture, and visual stress in a simulated “helo-hunch” posture. Background Military aviators frequently report neck pain (NP). Risk factors for NP include head-supported mass, awkward postures, and mental workload. Interactions between these factors could induce constant low-level muscle activation during helicopter flight and better explain instances of NP. Method Interactions between physical loading (helmet doffed/donned), posture (symmetric/asymmetric), and visual stress (low/high contrast) were studied through neck muscle electromyography (EMG), head kinematics, subjective discomfort, perceived workload, and task performance. Subjects ( n = 16) performed eight 30-min test conditions (varied physical loading, posture, and visual stress) while performing a simple task in a simulated “helo-hunch” seating environment. Results Conditions with a helmet donned had fewer EMG median frequency cycles (which infer motor unit rotation for rest/recovery, where more cycles are better) in the left cervical extensor and left sternocleidomastoid. Asymmetric posture (to the right) resulted in higher normalized EMG activity in the right cervical extensor and left sternocleidomastoid and resulted in less lateral bending compared with neutral across all conditions. Conditions with high visual stress also resulted in fewer EMG cycles in the right cervical extensor. Conclusion A complex interaction exists between the physical load of the helmet, postural stress from awkward postures, and visual stress within a simulated “helo-hunch” seating environment. Application These results provide insight into how visual factors influence biomechanical loading. Such insights may assist future studies in designing short-term administrative controls and long-term engineering controls.

Peculiarities of breath holding tests in school age children

Objective of the study was to examine the performance of breath-holding and Ruffier tests, relationship between them and other factors in healthy school age children.Material and methods. The cross-sectional descriptive study with 45 healthy participants in age 7-13 years (22 boys and 23 girls) was performed. The study included assessment of nutrition, physical activity habits, family and socioeconomic data, resting anthropometric and blood pressure measurements, pulse oximetry, tests for the functional status of the cardiorespiratory system and readiness of child organism for physical loading (Ruffier and volitional breath-holding hypoxic tests). Results. The Rufier index in most children was average and amounted to 8.75±0.32 units. Test with breath-holding on inspiration was at the level of 37.0±1.84 sec, on exhalation - 22.2±1.3 sec. In children with low tolerance to exercise during respiratory tests execution there were a decrease in blood saturation and changes in heart rate. The tests are based on different physiological processes in the human body that create physical load tolerance: heart tolerance and cardiorespiratory oxygen supply to tissues.Conclusions. All selected tests could be executed anywhere and in a short period of time. They are easy to perform and do not cause emotional reactions in children and could be used for tolerance for physical loading assessment. The results obtained are complementary and can be recommended for use in the complex when examining the health and tolerance for physical loading in children during different screening types.

Soldier Load Carriage, Injuries, Rehabilitation and Physical Conditioning: An International Approach

Soldiers are often required to carry heavy loads that can exceed 45 kg. The physiological costs and biomechanical responses to these loads, whilst varying with the contexts in which they are carried, have led to soldier injuries. These injuries can range from musculoskeletal injuries (e.g., joint/ligamentous injuries and stress fractures) to neurological injuries (e.g., paresthesias), and impact on both the soldier and the army in which they serve. Following treatment to facilitate initial recovery from injuries, soldiers must be progressively reconditioned for load carriage. Optimal conditioning and reconditioning practices include load carriage sessions with a frequency of one session every 10–14 days in conjunction with a program of both resistance and aerobic training. Speed of march and grade and type of terrain covered are factors that can be adjusted to manipulate load carriage intensity, limiting the need to adjust load weight alone. Factors external to the load carriage program, such as other military duties, can also impart physical loading and must be considered as part of any load carriage conditioning/reconditioning program.

DIAGNOSIS OF THE FUNCTIONAL STATE OF AUTONOMIC REGULATION AND PROGNOSIS OF MALADAPTATION DEVELOPMENT

It was demonstrated that medical students with vagotonia and sympathicotonia had a mild strain of their regulation mechanisms. The considerable signs of autonomic regulation inefficiency were found out in conditions of physical exercising. The adaptation of individuals with vagotonia to the physical loading was going mainly due to the excessive elevation of heart rate along with the increase in diastolic blood pressure. In contrast, abnormal elevation of pulse pressure after physical loading was observed in young people with sympathicotonia, which is concerned as a negative prognosis and also a predictor of arterial hypertension. Some physiological aspects of the recovery period confirmed the insufficiency of autonomic regulation as well as discoordination of the reciprocal departments of autonomic nervous system in examined persons. The unfavorable range of increase in hemodynamic parameters after physical loading was to pioneer. The following ranges of cardiovascular indexes indicated the mild level of maladaptation: in individuals with vagotonia – Mean Arterial Pressure by 6-30%, heart rate by 80-120%, endurance coefficient – 5-27%, and Robinson’s index – 121–200%; in persons with sympathicotonia – endurance coefficient – 5-27%, and Pulse Pressure – 75-105%. These changes have to be corrected in advance for the prophylactics of specific and nonspecific complications of visceral systems functioning. The economical effectiveness of this research is accomplished by the reduction of financial expenses because of prophylactics and/or diagnosis of autonomic deregulation development

The Accuracy of a Low-Cost GPS System during Football-Specific Movements

An affordable player monitoring solution could make the evaluation of external loading more accessible across multiple levels of football (soccer). The present study aimed to determine the accuracy of a newly designed and low-cost Global Positioning System (GPS) whilst performing match-specific movement patterns. Sixteen professional male football players (24 ± 3 years) were assigned a GPS device (TT01, Tracktics GmbH, Hofheim, Germany) and completed two experimental trials. In each trial, a continuous protocol including seven movements (sideways cornering, diagonal cornering, accelerating, decelerating, backwards jogging, shuttle running, and skipping) adding up to 500 m, was completed. Time-motion data was compared with criterion distance and velocity (photo-cell timing gates and radar). Validity was assessed through the standard error of the estimate (SEE) and reliability through the coefficient of variation (CV; both with 95% confidence limits). For the total distance covered during the protocol, the system was found to be valid (SEE = 3.1% [2.2; 5.8]) and reliable (intra-device CV = 2.0% [1.2; 7.6]). Similar results were found for velocity (SEE = 3.4% [2.6; 4.8], CV = 4.7% [3.2; 8.5]). In conclusion, the present GPS system, a low-cost solution, was found to be a valid and reliable tool for measuring physical loading during football-specific movements.