The diaphragm is well known for its role as the principal muscle of respiration. However, according to previous studies, its role is multifactorial, from breathing through pain perception, regulation of emotional sphere, collaborating in gastroesophageal functions, facilitating the venous and lymphatic return, to an essential role in the maintenance of lumbar spine stability. The purpose of the study was to examine whether diaphragm function parameters (thickness and range of motion) are associated with static balance maintenance. A total of 142 participants were examined and divided into three groups: G1—patients qualified for lung resection due to cancer; G2 –patients after lobe resection; G3 –healthy subjects. Diaphragm thickness and excursion was measured using ultrasonography. Stabilometric parameters of balance were assessed by Zebris FDM-S platform. Greater diaphragm thickening during active breathing and diaphragm thickness fraction were associated with better static balance parameters. Limitation of diaphragm motion during quiet breathing and deep breathing was linked to balance disorders. There was no correlation between diaphragm muscle excursion during sniff maneuvers and balance parameters. Deterioration of diaphragm function observed after thoracic surgery was closely related with deterioration of balance maintenance. Impairment of diaphragm function manifested by decrease of muscle thickness and movement restriction is strongly associated with balance disorders in a clinical sample and among healthy subjects.

BackgroundIn pursuit of improvement in cardiopulmonary resuscitation (CPR), new technologies for the measurement and assessment of CPR quality are implemented. In our study, we assessed the kinematics of the rescuer during continuous chest compression (CCC–CPR). The proper performance of the procedure is a survival predictor for patients with cardiac arrest (CA). The purpose of the study was a prospective assessment of the kinematics of the rescuer’s body with consideration given to the depth and rate of chest compression (CC) as the indicator of properly performed CC maneuver by professional and non-professional rescuers during a simulation of a 10-min CCC using a manikin.MethodsForty participants were enrolled in the study. CCC–CPR was performed in accordance with the 2015 AHA guidelines on a manikin positioned on the floor. Kinematic data on the movement were obtained from the measuring system (X-sens MVN Biomech) transmitting information from 17 inertial sensors. Measurement data were imported to the author’s program RKO-Kinemat written in the Matlab and C # environments. Two groups of results were distinguished: Group I—results of CC with the depth of ≥ 40 mm and Group 2—CC results with the depth of < 40 mm.ResultsThe multiple regression model demonstrated that the path length, left knee flexion angle, and left elbow flexion angle were the essential elements of the rescuer’s kinematics that facilitated achieving and maintaining the normal depth of CC.ConclusionsWe believe that raising the rescuer’s hips by moving the center of the rescuer’s body over the point of sternal compression increases the value of the CC force vector, thereby increasing the depth of CC. In addition, we observed that, during an effective CC, the rescuer was unable to maintain arms straight and, in consequence, a slight elbow flexion was observed. It, however, did not influence the quality of the maneuver.

The objective of the work was to determine biomechanical parameters influencing loads affecting the musculoskeletal system and shock absorption during the landing phase in Grand Jeté, Entrelacé and Ballonné. Methods: Motion kinematics measurements of the landing phase in GrandJeté, Entrelacé and Ballonné were carried out using the optical APAS system, and measurements of the GRF components-using Kistler platform. The research was carried out for three professional dancers. Kinematic and kinetic parameters of the landing were analysed. Results: The mean maximum GRF value in relation to the classical dancer amounted to 8.16 ± 1.37 N/BW. During landing, the joints of the lower limb are affected by external force moments of high values (ankle-3.04 ± 0.54 [Nm/BW], knee-7.56 ± 5.53 [Nm/BW], hip-10.97 ± 6.80 [Nm/BW]). The maximum value of the external force moments in the joint were strongly negatively correlated with the value of the angle in the hip joint at the moment of the first contact with the ground. It was noticed that the obtainment of maxGRF was preceded by a decrease in kinetic energy of approximately 50%. Conclusions: Factors affecting loads present in the musculoskeletal system during the shock absorption of a leap are: GRF values, the values of external force generated inside the joints and a change in the value of kinetic energy. The safe shock absorption after landing is influenced by properly positioned limb at the moment of the first contact, a greater range of movements in the joints and longer time from the moment of the first contact to the obtainment of maxGRF.

Background and objectives: Virtual reality (VR) is increasingly often finding applications in physiotherapy and health promotion. Recent years have seen the use of advanced technologies in the promotion of physical activity (PA) in society. New simulators, e.g., treadmills, enable the performance of PA (e.g., locomotive movements) in VR (artificially created virtual world). The question of how such movements are similar to natural forms of human locomotion (march, run) inspired the comparative analysis of physiological gait and gait in VR on a multidirectional Omni treadmill. Materials and Methods: The tests involved the use of the BTS Smart system for the triplanar analysis of motion. The test involved 10 healthy females aged 20–24 (weight: 52 ± 3.1 kg, height 162 ± 5.4 cm). Measurements were performed at two stages. The first stage involved the standard assessment of physiological gait, whereas the second was focused on gait forced by the Omni treadmill. The following gait parameters were analyzed: Flexion-extension in the ankle, knee joint and hip joint, rotation in the hip joint and knee joint, foot progression, adduction-abduction in the knee joint and hip joint, pelvic obliquity, pelvic tilt, pelvic rotation as well as energy expenditure and the movement of the body center of mass. Results: The analysis of the test results revealed the existence of differences in the kinematics of physical gait and gait on the treadmill. The greatest differences were recorded in relation to the dorsal-plantar flexion in the ankle, the foot progression, the rotation of the knee joint, pelvic tilt and rotation. In addition, the gait on the treadmill is characterized by the longer duration of the stance phase and reduced ranges of the following movements: Flexion-extension in the ankle, knee joint and hip joint, adduction-abduction in the hip joint as well as rotation in the ankle and hip joint. The values of potential, kinetic and total energy recorded in relation to forced gait are significantly lower than those of physiological gait. Conclusions: Because of the fact that the parameters of gait on the Omni platform vary significantly from the parameters of physical gait, the application of the Omni treadmill in the re-education of gait during rehabilitation should be treated with considerable care. Nonetheless, the treadmill has adequate potential to become a safe simulator enabling active motion in VR using locomotive movements.

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AIMS: To compare the differences in bone mineral density (BMD) at loaded and non-loaded skeletal sites in professional ballet dancers. We hypothesized that in both male and female elite ballet dancers, a significant difference in BMD will be observed between impact and non-impact sites. METHODS: 44 elite ballet dancers, 22 men (age 26.4±5.9 yrs) and 22 women (age 24.9±5.3 yrs), were examined. BMD measurements were performed using dual-energy x-ray absorptiometry at three skeletal sites—forearm (FA), lumbar spine (LS), and femoral neck (FN)—and analyzed using t-tests, ANOVA, and linear regression models. Information about career duration, training volume, health habits, and menstrual disorders (women) was collected. RESULTS: Z-scores for LS and FN were significantly higher in men than in women. However, Z-scores for FA were similar in men and women and fell below the expected range for age (<–2.0), and they were significantly lower than those for LS and FN. With longer career duration, a trend was observed towards lower Z-scores for FN in men and towards higher Z-scores for FA in women. CONCLUSION: In ballet dancers, FA mineralization is extremely low compared to loaded skeletal sites. Male dancers may have lowered forearm BMD despite the absence of risk factors present in female dancers (menstrual disorders). Professional ballet dancers may be at risk of local osteopenia due to the “local non-impact” characteristics of ballet dance, and use of the 33% distal radius region for the accurate assessment of bone mineral status should be investigated further in this population.

BackgroundThis paper presents a case study of kinematic analysis of the modern dance movement known as the “stag jump”. Detailed analysis of the kinematic structure of this movement as performed by the dancers, accompanied by measurements of impact forces during landing, will allow the authors to determine, in subsequent model-based research phases, the forces acting in knee joints of the lower landing limb.Material/MethodsTwo professional modern dancers participated in the study: a male and a female. The study consisted in recording the values of ground reaction and body motion, and then determining and analyzing kinematic parameters of performed movements.ResultsThe results of measurement of joint angles in the landing lower limb, pelvis, and foot position in relation to the ground, as well as the level of vertical components of ground reaction, provided insight into the loading response phase of the “stag jump”. The measurements and obtained results show differences between the man and woman in ground reactions and kinematic quantities.ConclusionsThe results obtained during the research may be used in the development and teaching of dancing movements. Training sessions, carried out in the biomechanical laboratory, with active participation of dancing teachers, could form a basis for a prevention model of injuries and physical overloads occurring within this occupational group.Primary differences in the “stag jump” performance technique probably result from the different educational path the man and the woman went through.

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