Padel is a rapidly growing sport with a large base of amateur players. One crucial technique for winning points, which many amateurs struggle with, is the smash. The combination of its importance and difficulty makes it a compelling topic for design innovation. The central question is: how can padel amateurs learn the smash faster?

This report describes the development and testing of a padel ball with fuzzy felt designed to improve amateur players’ smash performance. The project began with conceptualising various ideas that were based on literature research on 1) the sport padel, 2) the smash in padel, 3) biomechanics of the smash, 4) motor learning and 5) coordination. The fuzzy padel ball concept is selected due to its multidisciplinary characteristics and discovered gap in the market. It has the potential to lower ball speed when the amateur player receives a lob, providing them with more time to set up their smashes. This approach aims to improve the learning experience.

The manufacturing process of standard padel balls can in theory be modified slightly to create a fuzzier felt that covers the rubber balls. Machines are used to break the weaving structure of the felt that goes around the balls. This production step raises the fuzziness of the felt and causes an increase in drag, which slows down the ball. Going through this machine multiple times will increase the fuzz even more, something that existing padel ball companies already do to make their ball travel slightly slower through the air than their competitors. Since it was not possible to use professional rubber balls glued with fuzzier felt right away, prototypes were created using different fabrics glued to padel and tennis balls to simulate the concept.

The prototypes are used for multiple tests that investigate which of them travels slower through the air. These tests consist of a drop test (to measure the fall speed of the prototypes) and a smash test (to measure the smash performance of the best prototypes). In the smash test, nine participants received multiple lobs which they had to smash at a target mat at the other side of the net. Their smash accuracy and speed were recorded and combined to produce a smash performance score. Results showed no significant difference in smash performance between normal and fuzzy balls. However, players provided qualitative feedback on timing adjustments and perceived a slower ball speed during the lob and an increase in weight. In conclusion, padel amateurs can learn the smash faster by integrating biomechanics, motor learning, and coordination. The fuzzy felt padel ball concept provides a promising tool for achieving this, although further refinement and testing are necessary.

Future prototype development should use high-quality felt with varying fuzziness and explore different internal pressures to counteract damping effects. Glueing felt directly onto rubber balls improves prototype quality. Additionally, investigating the durability of prototypes, creating removable fuzzy covers for existing balls, and collaborating with established manufacturers could provide further insights. Another qualitative finding of this study was the psychological impact of sensory feedback. One player perceives that louder smashes are correlated with higher smash speeds, which is not the case. This aspect should be examined more closely in future research.
Future studies should refine the smash test setup, use a round target for better statistical comparisons, and engage a professional padel trainer for consistent lobs. Improved filming techniques, including slow motion and higher-quality cameras, will enhance data accuracy.
Although the primary hypotheses were not supported, the study provided valuable insights into the differences between the effect of using normal and fuzzy padel balls.

BACKGROUND: Rising UCL injury rates at both amateur and professional levels have been linked to fatigue in baseball pitchers. Repeated pitching has been associated with changes to kinematics, kinetics, and perceived fatigue, but no statistical model exists which incorporates all the most common aspects of fatigue into one framework. Confirmatory factor analysis (CFA) can be used to investigate possible fatigue frameworks and their plausibility in explaining the multivariate nature of observed changes occurring with repeated pitching. AIM: To investigate how multiple fatigue manifestations could be associated with a shared factor in baseball pitching. METHOD: Two CFA models were proposed; one a priori model based solely on previous findings and literature linking commonly found variables which change with repeated pitching, and one a posteriori model with added correlation factors between maximum external shoulder rotation (MER) with perceived fatigue and MER with triceps EMG activity. RESULTS: Model fitness test performed on the first a priori model proved plausible, with it passing some of the tests but failing others. The a posteriori model showed to be an excellent model for explaining the covariance of the data, passing all model fitness tests. CONCLUSIONS: Confirmatory factor analysis can serve to provide a plausible framework for explaining the covariance measured in kinematic, kinetic, and other fatigue related changes to baseball pitching data. Both models would suggest that the shared latent variable represents an underlying aspect of physiological fatigue. Changes to MER were determined to not be directly caused by fatigue. A proper understanding of different fatigue manifestations can potentially reduce the amount of fatigue related UCL injuries plaguing baseball pitchers by providing a more accurate proxy for measuring physiological fatigue.

Injury to the Ulnar Collateral Ligament (UCL) is common among baseball pitchers, due to high external valgus torques applied around the elbow during pitching. Literature shows that elbow muscles and the osseous articulation can lower the load imposed to the UCL by countering the external valgus moment. As the contribution of the individual elbow muscles and the osseous articulation to the UCL load during pitching remains unclear, this study aims to identify the muscles capable of (un)loading the UCL during baseball pitching. Muscle-driven simulations for ten baseball pitches were generated using a musculoskeletal (MSK) model of the upper extremity. The simulations were run twice: ones without any constrictions to the model and ones with the wrist motion locked. The flexor digitorum superficialis (FDS) was identified as biggest contributors to the internal muscle moment during the wrist-included simulations. The external valgus torque was 10% countered by the elbow muscles, 59% by the osseous articulation and 31% by the UCL. The UCL had to resist a moment of 25.6 Nm. During the wrist-excluded simulations, the flexor carpi radialis (FCR) and was identified as biggest contributors to the internal muscle moment. The external valgus torque was 10% countered by the elbow muscles, 42% by the osseous articulation and 48% by the UCL, resulting in a UCL moment of 39.4 Nm. Further research should focus on the influence of wrist and finger motion on UCL load and concentrate more on the osseous articulation as main elbow stabilizer during pitching.

Ulnar collateral ligament (UCL) injuries are common in baseball pitching. The elbow external valgus torque is assumed to be indicative for the applied load on the UCL. This study investigated the maximum external valgus and extension torque and their corresponding load variability during a baseball pitch and the relationship between the magnitude and the within-pitcher load variability of these elbow torques. Furthermore, this study investigated to what extend the elbow torques and the ball speed are related. Eleven Dutch AAA pitchers each threw 25 fastballs. The motion was captured with an optical motion capture system. The ball speed was measured with a radar gun. The data of the upper body, in particular the elbow torques, were analysed using a custom-made 3D inverse dynamics model. The results show that the within-pitcher load variability differs among pitchers. A higher applied elbow torque compared to other pitchers indicates a higher within-pitcher variability. From these results, both a higher valgus torque and a higher within-pitcher load variability are expected to lead to higher injury risk. It is advised not to take one pitch per pitcher into account since it cannot represent all the pitches, especially if only the fastest is selected. Among the pitchers, ball speed is found not to be a good indicator for the elbow torques. Within a pitcher, the ball speed serves better as an indicator. This study emphasises the importance of analysing each pitcher’s results individually instead of comparing them to the whole group.

Baseball pitching is a movement wherein an external valgus moment around the elbow joint regularly causes an ulnar collateral ligament (UCL) injury. A proven relationship between the muscle activation around the elbow joint and its capacity to compensate for the external valgus moment during a baseball pitch allows predicting the likelihood of a UCL injury within pitchers in the future.

The present study establishes the generic muscle activity around the elbow joint during a fastball baseball pitch to investigate the capacity of the muscles to compensate for the external valgus moment actively and thereby prevent a UCL injury.
Six uninjured, experienced recreational adult pitchers, participated in this study (age: 25 ± 2 years; body height: 188 ± 10 cm; body mass: 77 ± 15 kg). 2000 Hz surface ElectroMyoGraphy (sEMG) was used to measure the muscle activity around the elbow joint in 15 fastball pitches for each participant. Before the pitch measurement, participants had to perform maximum voluntary contractions (MVC).

The signals were corrected to an electromechanical delay of 50 ms and normalized to either MVC, or to the maximum of the signal itself. After that, the mean values were calculated for the instance of foot contact, maximum external rotation and ball release separately over the participants. A repeated measures ANOVA was performed to observe whether the mean activity is significantly higher at maximum external rotation compared to the moment of foot contact and ball release to compensate for the peak external valgus moment.

Significant peak activity was found at maximum external rotation for all muscles, compared to the instance of ball release. The parallel activity of the flexor pronator mass and m. pronator teres at maximum external rotation enhances a compensating effect to the external valgus moment by its directly counteracting tension. Furthermore, the results support a co-contraction between the flexor pronator mass:extensor supinator mass and m. triceps lateral head: m. biceps brachii muscle pairs to compensate for the external valgus moment by a compression force to the elbow joint. The generic function of the m. anconeus in the fastball baseball pitch is still debated due to the inconsistent results over the different pitchers in this study.

This study provides evidence that the muscles around the elbow joint can compensate for the external valgus moment during a fastball pitch. These results provide possibilities for using sEMG to assess the muscle activation pattern of individual pitchers as support to predict and prevent UCL injuries in pitchers in the future.

In baseball, pitchers have a high rate of throwing arm injury, which could lead to disability and less training time. This paper aims at investigating whether upcoming injuries of youth baseball pitchers can be detected before the athlete experiences injury symptoms. A total of 118 elite youth baseball pitchers from the Dutch national baseball team and six Dutch academies were followed over three years. Promising variables like Range of Motion, Muscle Force, Ball Speed and Training Time were included for use in a supervised classification problem. Prediction accuracy performance was then measured for different algorithms in the form of F1 and F2 scores. Results showed deficient performance for injury prediction using single-point-in-time measurements for all examined algorithms, with scores of both F1 and F2 reaching maximums of 0.5. The results, however, revealed the importance of measuring variables like hip force and hip range of motion for shoulder injury prediction, and force in the hip and shoulder together with the total rotational motion (TRM) of the shoulder for elbow injury prediction. Ball speed and training time contributed less for the tested models. Higher frequency data is needed for better injury prediction performance. Future studies are recommended to measure data with a time between measurements of one to two weeks. This high frequency makes it possible to use time-series analysis to detect slight asymptomatic pathology developments progressing over time, to help youth baseball pitchers avoid injuries and keep their performance ready for top-level play.