Asimetría entre los miembros superiores en jóvenes padelistas de competición / Upper Limbs Asymmetries in Young Competitive Paddle-Tennis Players

Existe escasa literatura sobre las asimetrías en el pádel, un deporte de naturaleza asimétrica. Para estudiar el desarrollo de asimetrías en este deporte se evaluó, con bioimpedancia, la masa magra de ambos miembros superiores de 96 jugadores de pádel jóvenes y de 76 esquiadores (grupo control) y se calculó el índice de simetría. Los jugadores de pádel tuvieron una asimetría entre ambos miembros superiores mayor que los esquiadores, cuando se consideró toda la muestra (7.2 ± 5 % vs. 1.4 ± 3.2 %; p < 0.001), en jugadores con un estado de madurez negativo (5,7 ± 3,2 % vs. 1,5 ± 3,8 %; p < 0,001) y en aquellos con un estado de madurez positivo (8,3 ± 5,8 % vs. 1,3 ± 2,4 %; p < 0,001). Este estudio revela que el pádel genera asimetrías de masa magra en los miembros superiores, incluso antes de la edad de crecimiento pico. (AU)

There is little literature on asymmetries in paddle tennis, a sport of an asymmetrical nature. To study the development of upper limb asymmetries, 96 young paddle players and 76 skiers (control group) were evaluated via bioimpedance. The lean mass symmetry index was then compared, considering the sport (paddle tennis players and skiers) and the maturity offset (positive or negative). Paddle-tennis players had a systematically greater upper limbs asymmetry than skiers (7.2 ± 5 % vs. 1.4 ± 3.2 %; p < 0.001). This also occurs when comparing only the subsamples with a negative maturity offset (5.7 ± 3.2 % vs. 1.5 ± 3.8 %; p < 0.001) or with a positive maturity offset (8.3 ± 5.8 % vs. 1.3 ± 2.4 %; p < 0.001). The study reveals that paddle tennis generates asymmetries of lean mass in upper limbs, even before growth spurt. (AU)

The Utility of a High-intensity Exercise Protocol to Prospectively Assess ACL Injury Risk.

This study investigated the utility of a 5-min high-intensity exercise protocol (SAFT(5)) to include in prospective cohort studies investigating ACL injury risk. 15 active females were tested on 2 occasions during which their non-dominant leg was analysed before SAFT(5) (PRE), immediately after (POST0), 15 min after (POST15), and 30 min after (POST30). On the first occasion, testing included 5 maximum isokinetic contractions for eccentric and concentric hamstring and concentric quadriceps and on the second occasion, 3 trials of 2 landing tasks (i. e., single-leg hop and drop vertical jump) were conducted. Results showed a reduced eccentric hamstring peak torque at POST0, POST15 and POST30 (p<0.05) and a reduced functional HQ ratio (Hecc/Qcon) at POST15 and POST30 (p<0.05). Additionally, a more extended knee angle at POST30 (p<0.05) and increased knee internal rotation angle at POST0 and POST15 (p<0.05) were found in a single-leg hop. SAFT(5) altered landing strategies associated with increased ACL injury risk and similar to observations from match simulations. Our findings therefore support the utility of a high-intensity exercise protocol such as SAFT(5) to strengthen injury screening tests and to include in prospective cohort studies where time constraints apply.

Effect of a Home-based Balance Training Protocol on Dynamic Postural Control in Subjects with Chronic Ankle Instability.

The aim of this study was to establish the presence of postural deficits in subjects with chronic ankle instability (CAI) and to assess the effect of an 8-week balance training program on dynamic postural control. A total of 43 subjects with CAI and 31 controls participated in this case-control study. Participants with CAI performed an 8-week home-based balance training, including 3 sessions a week. As main outcome measure, postural control was quantified after a vertical drop by means of the dynamic postural stability index (DPSI). Perceptual outcomes were documented using the FADI, FADI-Sport and VAS scales. At baseline, subjects with CAI displayed higher anterior/posterior and vertical postural instability, a poorer DPSI, and lower subjective stability scores compared to the control group. After balance training, all subjective stability scores improved significantly, although no changes were noted for the stability indices. In conclusion, subjects with CAI have an impaired postural control. As a treatment modality, balance training exhibits the capability of improving the subjective feeling of instability in subjects with CAI. However, there was no effect on dynamic postural control. Further research on the explanatory mechanisms of balance training is warranted, and other training modalities should be considered.

Asymmetry after hamstring injury in English Premier League: issue resolved, or perhaps not?

Hamstring injuries constitute one of the most concerning injuries in English Premier League football, due to its high primary incidence but also its recurrence. Functional methods assessing hamstring function during high-risk performance tasks such as sprinting are vital to identify potential risk factors. The purpose of this study was to assess horizontal force deficits during maximum sprint running on a non-motorized treadmill in football players with previous history of hamstring strains as a pre-season risk-assessment in a club setting. 17 male football players from one Premier League Club were divided into 2 groups, experimental (n=6, age=24.5±2.3 years) and control (n=11, age=21.3±1.2 years), according to history of previous hamstring injury. Participants performed a protocol including a 10-s maximum sprint on a non-motorized treadmill. Force deficits during acceleration phase and steady state phases of the sprint were assessed between limbs and between groups. The main outcome measures were horizontal and vertical peak forces during the acceleration phase or steady state. There were no significant differences in peak forces between previously injured and non-injured limbs, or between groups, challenging the ideas around functional force deficits in sprint running as a diagnostic measure of hamstring re-injury risk.

Effect of tape on dynamic postural stability in subjects with chronic ankle instability.

The objective of our study was to evaluate the effect of taping on the dynamic postural stability during a jump landing protocol in subjects with chronic ankle instability (CAI). For this purpose, 28 subjects with CAI performed a sagittal and frontal plane landing task in a non-taped and taped condition. As main outcome measure, the dynamic postural stability index (DPSI) was calculated. In addition, subjective feelings of instability and perceived difficulty level were assessed. Furthermore, mechanical effectiveness of the tape on the ankle joint was determined by registering 3D kinematics. 3 subjects were excluded based on discomfort during the landing protocol. Study results indicated that the tape reduced plantar flexion and inversion at the ankle at touchdown and range of motion in the landing phase. There was, however, no effect on the DPSI or on its directional subcomponents. Subjective feelings of stability with tape improved significantly, whereas perceived difficulty did not change. In conclusion, our taping procedure did not improve postural control during a sagittal and frontal plane landing task in subjects with CAI. Perceived instability did improve and is considered an important treatment outcome, which suggests that taping could be considered as a treatment modality by clinicians.

The trajectory of the centre of pressure during barefoot running as a potential measure for foot function.

The main purpose of this study was to describe and interpret the COP trajectory during barefoot running in a large cohort of young adults with no history of injury. COP data were collected from 215 subjects, who ran at 3.3 ms(-1) over a 16.5m long track, with a built in Footscan pressure platform. COP data were filtered using a 50 Hz lowpass butterworth filter and normalised. Reliability was then studied and mean curves were calculated for medial-lateral displacement (COP(x)) and velocity (v(x)COP), anterior-posterior displacement (COP(y)) and velocity (v(y)COP) as well as for the resultant velocity (v(xy)COP). Displacement and velocity of the COP provided insight over functional foot behaviour. A medially oriented peak in v(x)COP was found, which may reflect the fast initial pronation. A laterally oriented second peak in v(x)COP, together with a second peak in v(y)COP, indicated a fast forward shift of the COP over the lateral border of the foot during forefoot contact phase. During the forefoot push off phase, at the level of the metatarsals, anterior velocities of the COP were low and reflected the importance of the forefoot during push off. Finally, the COP course was studied for high arch, normal and low arch feet and indicated, a more lateral COP course for the low arch feet.

A functional foot type classification with cluster analysis based on plantar pressure distribution during jogging.

The purpose of this study was to establish a reference dataset for peak pressures and pressure-time integrals during jogging, to compare this reference dataset with existing walking data and to develop a foot type classification, all based on plantar pressure data obtained from 215 healthy young adults. The subjects ran at 3.3 m s(-1) over a 16.5 m long running track, with a built-in pressure platform mounted on top of a force platform. Peak pressures, regional impulses and relative regional impulses were measured. These variables were found to be reliable (all intra class correlation coefficients above 0.75) and, except for the heel areas, gender and asymmetry effects could be neglected. Highest peak pressures were found under the heel due to large impact forces during initial contact phase (ICP). In the forefoot, the highest peak pressure was found under the second metatarsal (64.2 +/- 21.1 N cm(-2)). Compared to walking data, overall higher peak pressures and impulses and difference in hallux loading were found during barefoot jogging. Four pressure loading patterns were identified using a K-means cluster analysis, based on the relative regional impulses underneath the forefoot: medial M1 pattern, medial M2 pattern, central pattern and central-lateral pattern. These four pressure loading patterns could help in the functional interpretation of the foot behaviour during the stance phase in slow running.

Necessary precautions in measuring correct vertical jumping height by means of force plate measurements.

The present study was designed to investigate the determination of vertical jumping height by means of force plate measurements. Four different sources of error influence this determination: the measurement of body mass, the determination of take off, the integration frequency, and the assessment of the initial conditions influencing the determination of the start of the movement. A theoretical model was utilized to simulate the vertical ground reaction forces in vertical jumping and to compare the outcome of analytical and numerical double integration of the vertical acceleration of the body centre of mass. A high integration frequency and an optimizing loop for body mass determination were found to be important and should be taken into account when determining jumping height parameters.