The avoidance of respiratory muscle fatigue and its repercussions may play an important role in swimmers’ health and physical performance. Thus, the aim of this study was to investigate whether a six-week moderate-intensity swimming intervention with added respiratory dead space (ARDS) resulted in any differences in respiratory muscle variables and pulmonary function in recreational swimmers. A sample of 22 individuals (recreational swimmers) were divided into an experimental (E) and a control (C) group, observed for maximal oxygen uptake (VO₂max). The intervention involved 50 min of front crawl swimming performed at 60% VO₂max twice weekly for six weeks. Added respiratory dead space was induced via tube breathing (1000 mL) in group E during each intervention session. Respiratory muscle strength variables and pulmonary and respiratory variables were measured before and after the intervention. The training did not increase the inspiratory or expiratory muscle strength or improve spirometric parameters in any group. Only in group E, maximal tidal volume increased by 6.3% (p = 0.01). The ARDS volume of 1000 mL with the diameter of 2.5 cm applied in moderate-intensity swimming training constituted too weak a stimulus to develop respiratory muscles and lung function measured in the spirometry test.

We consider a classical spring-mass model of human running which is built upon an inverted elastic pendulum. Based on previous results concerning asymptotic solutions for large spring constant (or small angle of attack), we introduce an analytical approximation of a reduced mapping. Although approximate solutions already exist in the literature, our results have some benefits over them. They give us an advantage of being able to explicitly control the error of the approximation in terms of the small parameter, which has a physical meaning—the inverse of the square-root of the spring constant. Our approximation also shows how the solutions are asymptotically related to the magnitude of attack angle $\alpha $. The model itself consists of two sets of differential equations—one set describes the motion of the centre of mass of a runner in contact with the ground (support phase), and the second set describes the phase of no contact with the ground (flight phase). By appropriately concatenating asymptotic solutions for the two phases we are able to reduce the dynamics to a one-dimensional apex to apex return map. We find sufficient conditions for this map to have a unique stable fixed point. By numerical continuation of fixed points with respect to energy, we find a transcritical bifurcation in our model system.

This work aimed to develop a model to assess the likelihood of injury in track and field athletes, and to establish which factors have the greatest impact. Tests verifying their significance were also reviewed, as well as the method for selecting variables. The key element was to confirm the quality of the classification system and to test the impact of individual factors on the likelihood of injury. The survey was carried out among physically active participants who take part in track and field sporting disciplines. The Cronbach’s alpha was 0.73, which can be considered an acceptable value for the survey. The seven most important factors influencing the risk of injury were selected from a group of twenty-four and were used to create the model. The Nagelkerke’s R2 reached 0.630 for the logit model, which indicates a good effect of the independent variables. The data suggested that the largest factor influencing the risk of injury was the number of prior injuries.

A novel application of spring-loaded inverted pendulum model is proposed in this study. In particular, we use this model to find the existence of so-called fixed points, which correspond to actual running gaits, as functions of model parameters such as stiffness and energy. Applying the model to experimental data allows us to draw justifiable conclusions on mechanical energy minimisation for running gaits. The data were collected during a study witch 105 athletes. Force was measured using a pressure plate integrated in a treadmill. Kinematic data were recorded using two high-speed video cameras and an accelerometer placed on the back sacral localization. Each athlete completed trials by running at four different targeted velocities (9, 12.5, 16, 19.5 km/h). Running velocity influenced the values of the leg spring stiffness approximations, while the values of stiffness, determined using data from the pressure plate and camera, vary only slightly. The mechanical energy corresponding to periodic running gaits was studied with leg stiffness determined from the experiment. The mechanical energy of the runner slightly exceeded the minimum value of energy required for the existence of fixed points in the model. These results contribute to the general understanding of running gaits in terms of mechanical energy optimization.

Background/Objectives: This study aimed to characterize macro- and micro-morphological properties of the supraspinatus tendon (SST) in para swimmers during the chronic stage of rotator cuff tendinopathy, integrating ultrasound assessments of tendon thickness, peak spatial frequency radius (PSFR) for collagen organization, acromiohumeral distance (AHD), and occupation ratio to evaluate subacromial impingement risk. Methods: In a cross-sectional design, 43 elite para swimmers (aged 18–30 years, S7–S10 classes with lower extremity impairments) from Para Swimming Team Poland were divided into rotator cuff tendinopathy (RC; n = 22) and asymptomatic control (CON; n = 21) groups. Measurements on the dominant shoulder utilized B-mode ultrasound (Alpinion X-CUBE 90) to assess SST thickness at 5, 10, and 15 mm proximal to the greater tuberosity, PSFR via MATLAB-analyzed spatial frequency spectra, AHD, and occupation ratio. Two-way and one-way ANOVAs assessed group and measurement effects (p < 0.05); Pearson correlations examined the relationships between thickness and PSFR. Results: Para swimmers with tendinopathy exhibited greater SST thickness across sites (p < 0.001, η² = 0.63), higher PSFR at all intervals (p ≤ 0.009, η² = 0.53) peaking at 10 mm, wider AHD (p = 0.002, η² = 0.21), and lower occupation ratio (p < 0.001, η² = 0.44) versus controls. Strong positive correlations linked thickness and PSFR proximally (r = 0.75–0.79, p < 0.001). Conclusions: Chronic tendinopathy in para swimmers manifests as thickened SST with collagen disarray, altered subacromial space, and impingement risk, distinguishing pathological from healthy tendons. Integrated ultrasound metrics aid diagnosis and inform interventions for overhead athletes with locomotor disorders.