Standard Mobile Phones Plus a Balance Board Are Sufficient: Designing a Serious Game for Better Knee Rehabilitation.

The rehabilitation process after knee injuries is often challenging for patients and requires a high level of resilience, as it involves the frequent repetition of mostly monotonous exercises. Based on recent research, serious games can significantly improve motivation by merging exercising with entertainment aspects and even combining it with hardware to apply external tasks and track the progress. The aim of this research is to propose and evaluate a new serious game pattern. The development is performed using systematic feedback from domain experts. The test setup involves analysis of patients' feedback. The final game comprises an interaction with a balance board and an attached smartphone. Evaluation showed two main results. From a technical point of view: sensors of a standard smartphone (and it's sensitivity) paired with a PC and its screen are usable in a rehabilitation setting. From a psychological point of view: the motivation to perform the knee rehabilitation process can be enhanced with a serious game delivering entertaining aspects to it.

A kinematic model for assessment of hip joint range-of-motion in fast sport movements using spreading angles.

The work investigates the relationship between the leg spread and hip joint flexibility during kicking action of highly skilled martial artists. Vector-based spreading angles (VSAs), as a simplified way to assess kick execution patterns and movement ranges, are proposed. The first VSA measures the angle between the two femur vectors (i.e., upper leg spread), whereas the second describes the full-leg spread. The proposed measures were applied to 3D motion analysis performed on 33 participants at various skill levels who executed double side kicks and performed two static flexibility tests (hip joint flexion and abduction). Statistical analysis showed that the proposed parameters differentiate between skill levels. Both VSAs and VSA rate of change showed high Pearson correlation to the quality of execution (the average of 10 subjective kickboxing experts' evaluation scores) at critical instants of the kick execution , i.e., during the first leg elevation and kick (angles: ρ > 0.8; p < 0.001). In addition, they significantly correlated to maximum static hip abduction at any instant (ρ = 0.37-0.69; p < 0.05). The work established that both static and dynamic joint flexibility contribute to high-performance levels and could be used for initial selection and assessment of training effectiveness.

Concurrent Validity of Field-Based Diagnostic Technology Monitoring Movement Velocity in Powerlifting Exercises.

ABSTRACT: Mitter, B, Hölbling, D, Bauer, P, Stöckl, M, Baca, A, and Tschan, H. Concurrent validity of field-based diagnostic technology monitoring movement velocity in powerlifting exercises. J Strength Cond Res 35(8): 2170-2178, 2021-The study was designed to investigate the validity of different technologies used to determine movement velocity in resistance training. Twenty-four experienced powerlifters (18 male and 6 female; age, 25.1 ± 5.1 years) completed a progressive loading test in the squat, bench press, and conventional deadlift until reaching their 1 repetition maximum. Peak and mean velocity were simultaneously recorded with 4 field-based systems: GymAware (GA), FitroDyne (FD), PUSH (PU), and Beast Sensor (BS). 3D motion capturing was used to calculate specific gold standard trajectory references for each device. GA provided the most accurate output across exercises (r = 0.99-1, ES = -0.05 to 0.1). FD showed similar results for peak velocity (r = 1, standardized mean bias [ES] = -0.1 to -0.02) but considerably less validity for mean velocity (r = 0.92-0.95, ES = -0.57 to -0.29). Reasonably valid to highly valid output was provided by PU in all exercises (r = 0.91-0.97, ES = -0.5 to 0.28) and by BS in the bench press and for mean velocity in the squat (r = 0.87-0.96, ES = -0.5 to -0.06). However, BS did not reach the thresholds for reasonable validity in the deadlift and for peak velocity in the squat, mostly due to high standardized mean bias (ES = -0.78 to -0.63). In conclusion, different technologies should not be used interchangeably. Practitioners who require negligible measurement error in their assessment of movement velocity are advised to use linear position transducers over inertial sensors.

Kinematic analysis of the double side kick in pointfighting, kickboxing.

The double side kick is a frequently used technique in pointfighting on which most offensive kicking techniques are based on. The aim of the study was to identify parameters, e.g., trunk and leg positions, durations and velocities that affect successful technique execution. 44 fighters, male and female, including European and World champions, participated in the research. The participants performed double side kicks to a punching bag with the target at chest level. 10 international experts scored (1-10 points; interrater correlation ICC (3,1): 0.952) videos of the best individual trial for quality of technique execution. Based on the average of the scores participants were categorised into 2 equally sized groups. For kinematic data acquisition, a Vicon 3D-motion capturing system was used. The normalised knee height of the kick leg (KHK), normalised absolute distance to the frontal shoulder (DKS) at the end of both chambering phases, the horizontal velocity during both chambering phases (KEV), the durations of all 6 functional phases and total duration, were analysed. KHK1, KHK2, DKS1 and DKS2, total duration as well as 4 out of 6 phase durations and KEV1 showed significant differences between groups in two-sided t-test or Mann-Whitney U-test for not normally distributed variables.