Klaus Mattes

The objective was to examine differences in the gait-specific cognitive representation structures between individuals after total knee- (TKA) and after total hip-joint arthroplasty (THA). The cognitive representation structure was compared between three groups: 1. three months after TKA (n = 12), 2. three months after THA (n = 12), and 3. healthy control group (CG) (n = 12) using the structural dimensional analysis of mental representation (SDA-M). Additionally, perceived joint function was rated by either the KOOS, JR. or HOOS, JR. Mean distribution of perceived joint function was not significantly different between the TKA (60.35 ± 11.2) and THA group (68.01 ± 13.8) (t = − 1.425; p = .173). In the cognitive representation structure, the THA group exhibited functional differences from the TKA group and control group, both of which showed a functional structure. Three months after hip joint replacement the gait-specific cognitive representation structure seems to reflect joint function-specific deviations. Therefore, focussing on functional recovery of cognitive gait representation may facilitate gait rehabilitation in individuals after hip replacement.

(1) Background: In the context of nursing challenges and workforce shortages, nurses experience significant physical and psychological strain due to manual patient handling. (2) Methods: This study investigates differences in nurses’ upper body postures, patient turning acceleration, and perceived exertion during a typical repositioning process within two repositioning maneuvers. (3) Results: The results reveal variations in positioning duration, upper-body posture angles, and turning acceleration between nurses and sequences. Nurse 2 exhibits more extreme postures (e.g., lateral flexion p < 0.001) and accelerations (e.g., shoulder p < 0.001) but reports lower perceived exertion (p = 0.03). (4) Discussion: These findings emphasize the need for ergonomic adherence and targeted training to enhance patient repositioning. Comprehensive solutions are necessary for patient and nurse comfort, particularly in cases of higher patient weights. Against the background of ergonomic body posture, this study highlights the potential of innovative tools and ongoing research to alleviate physical strain and enhance patient care.

Fatigue has the potential to alter how impact forces are absorbed during running, heightening the risk of injury. Conflicting findings exist regarding alterations in both kinematics and plantar pressure. Thus, this systematic review and subsequent meta-analysis were conducted to investigate the impact of general and localized muscle fatigue on kinematics and plantar pressure distribution during running. Initial searches were executed on 30 November 2021 and updated on 29 April 2023, encompassing PubMed, The Cochrane Library, SPORTDiscus, and Web of Science without imposing any restrictions on publication dates or employing additional filters. Our PECOS criteria included cross-sectional studies on healthy adults during their treadmill running to mainly evaluate local muscle fatigue, plantar pressure distribution, biomechanics of running (kinematics, kinetics, and EMG results), and temporospatial parameters. The literature search identified 6626 records, with 4626 studies removed for titles and abstract screening. Two hundred and one articles were selected for full-text screening, and 20 studies were included in qualitative data synthesis. The pooled analysis showed a non-significant decrease in maximum pressure under the right forefoot’s metatarsus, which was more than the left rearfoot after local muscle fatigue at a velocity of 15 km/h (p-values = 0.48 and 0.62). The results were homogeneous and showed that local muscle fatigue did not significantly affect the right forefoot’s stride frequency and length (p-values = 0.75 and 0.38). Strength training for the foot muscles, mainly focusing on the dorsiflexors, is recommended to prevent running-related injuries. Utilizing a standardized knee and ankle joint muscle fatigue assessment protocol is advised. Future experiments should focus on various shoes for running and varying foot strike patterns for injury prevention.

In this study, a prototype of an inertial sensor-based gait sonification system was tested for the purpose of providing real-time gait feedback on the knee angle. The study consisted of two parts: (1) a comparison of the knee angle measurement to a marker-based 3D optical capturing system (Vicon, Oxford, UK) with N = 24 participants and (2) an evaluation four different sonification feedback versions in an accentuation × pitch (2 × 2) design on a sample of N = 28 participants. For the measurement system comparison, the RMSE was 7.6° ± 2.6° for the left and 6.9° ± 3.1° for the right side. Measurement agreement with bias up to −7.5° ± 6.2° (for maximum knee flexion) was indicated by the Bland–Altmann Method. The SPM revealed significant differences between both measurement systems for the area 45–90% (p < 0.001) (left) and the area between 45% and 80% (p = 0.007) (right). For the sonification perception, the variation of pitch had a significant effect on the perception of pleasantness of the sound. No effect was found for the accentuation of the swing or stance phase.

Two variants of leg repositioning are described biomechanically and examined for differences in step kinematics. Based on leg angle (two-point angle between radius of leg centre of gravity and a horizontal line) during air phase, 30 juniors were divided into two groups (n = 15), large leg angle (LLA, leg angle = 80 ± 4°) and small leg angle (SLA, leg angle = 69 ± 5°). Maximal flying 30-m sprints were recorded (200 fps) and group differences were analysed using a 5-point leg model. With comparable leg length, both groups differed in leg moment of inertia and leg angular velocity. Group SLA reduced knee angle under the body, the thigh of swing leg passed the support leg early, and reached a higher position during knee lift, followed by a higher vertical foot velocity during pre-support. At take-on, both groups achieved a comparable hip, knee and foot angle. Due to higher mass of thigh (66%) compared to lower leg, foot and spikes (34%), thigh movement is essential for repositioning. Despite SLA advantages, three of the six fastest sprinters (v > 10.4 m/s) were evenly divided into both groups. An influence on step length, step frequency, ground contact and flight time was not found.

Maximum sprinting speed constitutes an optimum relation between the stride length and the step rate in addition to an appropriate sprinting technique. The kinematics of the sprint step at maximum sprinting speed have already been examined in numerous studies, without reaching a consensus. The aim of this study was to analyze the relationship between maximum sprinting speed and the stride kinematics based on the “Swing-Pull Technique”. German elite sprinters (N = 26, body height = 182 ± 6 cm, leg length 93.8 ± 4.1 cm) were tested while performing a 30-meter flying sprint at maximum sprinting speed. The relationship between sprinting speed and kinematic variables was determined via Pearson correlation. Sprinting speed (10.1 – 11.3 m/s) correlated with stride length (r = 0.53), ground contact time (r = -0.53) and variables from the technique model: the knee angle at the end of the knee lift swing (r = 0.40), the maximum knee angle prior to backswing (r = 0.40), the hip extension angle velocity (r = 0.63), and vertical foot velocity (r = 0.77) during pre-support, the ankle angle at the take-on (r = -0.43), knee flexion (r = -0.54), and knee extension (r = -0.47) during support. The results indicate that greater stride length, smaller contact time, and the mentioned kinematic step characteristics are relevant for the production of maximum sprinting speed in athletes at an intermediate to advanced performance level. The association of sprinting speed and these features should primarily be taken into account in conditioning and technical training.

The geometry of sweep rowing causes an asymmetrical movement with uneven force distribution on both sides of the body. The aim of this study was to investigate the asymmetry of the stretcher force for junior women and men. Four rowing eight-crews (N = 32) completed a stroke rate test and a 2000 m race. The rowing angle, the handle force and the stretcher force for the inside (oarside) and outside (non oarside) leg were measured. In both sub-samples, the outside leg stretcher force was higher than the inside leg stretcher force. The women rowed with higher symmetry index of stretcher force (26.8 ± 19.7%) than the men (8.6 ± 15.9%). This asymmetry was reduced with increasing stroke rate but increased with physical fatigue in the course of the rowing race. The transmission to the oar via trunk and arms is associated with unequal loading of the pelvis and lumbar spine. Female and male sweep rowers with high asymmetry of the stretcher force should use appropriate strength and technique training to reduce the asymmetry and the risk of low back pain.