Myotendinous asymmetries derived from the prolonged practice of badminton in professional players

The Association of Genetic Variants Within the Type XII Collagen and Tenascin C Genes with Knee Joint Laxity Measurements

BACKGROUND/OBJECTIVES

Types I, V, and XI collagen gene variants have been reported to associate with measurements of knee joint laxity and/or absolute knee ligament length changes. Type XII collagen and tenascin C are also ligament structural proteins whose expression is regulated by mechanical loading. This study investigated whether COL12A1 and TNC variants are associated with knee laxity and/or ligament length changes.

METHODS

Genu recurvatum, anterior-posterior tibial translation, external-internal tibial rotation, and ligament length changes were measured in 128 healthy participants. They were genotyped for COL12A1 (rs970547) and TNC (rs1061494, rs2104772, rs1138545).

RESULTS

Both the COL12A1 AA and TNC rs1061494 TT genotypes were associated with decreased external (p = 0.007, p = 0.010) and internal (p = 0.025, p = 0.002) rotation, as well as slack (p = 0.033, p = 0.014), in the dominant leg. Both genotypes, together with sex, weight, and/or COL1A1 genotypes, explained 26% and 32% of the variance in external and internal rotation, respectively. The TNC genotype, sex, and BMI explained 23% of the variance in slack. The COL12A1 AA and the TNC rs1061494 TT genotypes were associated with smaller changes in the MCL (aMCL: COL12A1 p = 0.009, TNC p = 0.045; iMCL: COL12A1 p = 0.004, TNC p = 0.043; pMCL: COL12A1 p = 0.003, TNC p = 0.067; aDMCL: COL12A1 p = 0.007, TNC p = 0.020; pDMCL: COL12A1 p = 0.007, TNC p = 0.023) and/or LCL (COL12A1 p = 0.652, TNC p = 0.049) lengths within the dominant knee. The TNC rs1061494 CC genotype was associated with larger changes in the non-dominant anterior (p = 0.021) and posterior (p < 0.001) ACL bundle lengths.

CONCLUSIONS

These findings suggest that COL12A1 and TNC variants are associated with internal-external tibial rotation and knee ligament length changes in healthy individuals.

Reliability of MyotonPro in measuring the biomechanical properties of the quadriceps femoris muscle in people with different levels and types of motor preparation

The aim of this research was to evaluate the reliability of the measurements of biomechanical parameters of the muscles of athletes representing different disciplines as well as untrained people. Ninety-four young, healthy male individuals participated in the study and were divided into five subgroups: footballers (n = 25), volleyballers (n = 14), handballers (n = 19), MMA fighters (n = 16), and undrained group (n = 20). All of the participants underwent measurements of stiffness (S), muscle tone (T) and elasticity (E) by two independent measurers using MyotonPro equipment. Analysis was conducted on two different parts of the quadriceps femoris: rectus femoris (RF) and vastus medialis (VM. Consequently, the comprehensive analysis comprised 564 measurements (94 participants * 3 parameters = 282 * 2 measurers = 564). The results proves high reliability of the myotonometry (Pearson's CC over 0.8208-0.8871 for different parameters, ICC from to 0.74 to 0.99 for different muscles and parameters) excluding only stiffness for the VM which was characterized withlow ICC of 0.08 and relatively highest between the examined parameters MAE% of 8.7% which still remains low value. The most significant differences between the parameters in examined groups were observed between MMA fighters and volleyballers in terms of muscle tone and elasticity of the VM (correlation of 0.14842 and 0.15083 respecitively). These results confirm the usability of myotonometry in measuring the biomechanical properties of the muscles in different sports groups and confirm the independence of the results obtained from the person performing the measurement.

The Myometric Assessment of Achilles Tendon and Soleus Muscle Stiffness before and after a Standardized Exercise Test in Elite Female Volleyball and Handball Athletes-A Quasi-Experimental Study

Background: The high prevalence of injuries in female athletes necessitates a course of action that not only enhances research in this field but also incorporates improved prevention programs and regular health monitoring of highly stressed structures such as tendons and muscles. Since myometry is already used by coaches and physiotherapists, it is important to investigate whether tissue stiffness varies in different types of sports, and whether such measures are affected by an acute training session. Methods: Myometric measurements of the Achilles tendon (AT) and soleus muscle (SM) were performed in the longitudinal plane and relaxed tendon position. In total, 38 healthy professional female athletes were examined, applying a quasi-experimental study design, with subgroup analysis performed for different sports. To investigate the stiffness of the AT and SM, 24 female handball and volleyball athletes performed a standardized maximal incremental performance test on a treadmill. In this subgroup, myometric measurements were taken before and after the exercise test. Results: The measurements showed no significant difference between the mean pre- (AT: 661.46 N/m; SM 441.48 N/m) and post-exercise stiffness (AT: 644.71 N/m; SM: 439.07 N/m). Subgroup analysis for different types of sports showed significantly lower AT and SM stiffness in swimming athletes compared to handball (p = 0.002), volleyball (p = 0.000) and hammer throw athletes (p = 0.008). Conclusions: Myometry can be performed on the same day as an acute training session in healthy female professional volleyball and handball athletes. Female swimmers have significantly lower AT and SM stiffness compared to female handball, volleyball and hammer throw athletes. These results show that the stiffness differences in the AT and SM can be assessed by myometry.

Multimodal sensorimotor assessment of hand and forearm asymmetries: a reliability and correlational study

Background

Effective rehabilitation of upper limb musculoskeletal disorders requires multimodal assessment to guide clinicians' decision-making. Furthermore, a comprehensive assessment must include reliable tests. Nevertheless, the interrelationship among various upper limb tests remains unclear. This study aimed to evaluate the reliability of easily applicable upper extremity assessments, including absolute values and asymmetries of muscle mechanical properties, pressure pain threshold, active range of motion, maximal isometric strength, and manual dexterity. A secondary aim was to explore correlations between different assessment procedures to determine their interrelationship.

Methods

Thirty healthy subjects participated in two experimental sessions with 1 week between sessions. Measurements involved using a digital myotonometer, algometer, inclinometer, dynamometer, and the Nine-Hole Peg test. Intraclass correlation coefficients, standard error of the mean, and minimum detectable change were calculated as reliability indicators. Pearson's correlation was used to assess the interrelationship between tests.

Results

For the absolute values of the dominant and nondominant sides, reliability was 'good' to 'excellent' for muscle mechanical properties, pressure pain thresholds, active range of motion, maximal isometric strength, and manual dexterity. Similarly, the reliability for asymmetries ranged from 'moderate' to 'excellent' across the same parameters. Faster performance in the second session was consistently found for the Nine-Hole Peg test. No systematic inter-session errors were identified for the values of the asymmetries. No significant correlations were found between tests, indicating test independence.

Conclusion

These findings indicate that the sensorimotor battery of tests is reliable, while monitoring asymmetry changes may offer a more conservative approach to effectively tracking recovery of upper extremity injuries.

Performance Differences in Elite National Basketball Association and Women's National Basketball Association Players Based Upon Whether the Dominant or Non-dominant Achilles Tendon Was Ruptured

Background National Basketball Association (NBA) and Women's National Basketball Association (WNBA) players with Achilles tendon ruptures have previously been noted to have a significant decline in performance post-injury. There has been recent anecdotal evidence that elite players with dominant Achilles tendon ruptures may be able to return at a higher level of play post-rupture. Objective This study aimed to evaluate for any differences in performance in higher-performing NBA and WNBA players with dominant versus non-dominant Achilles tendon ruptures pre- and post-injury. Methods This study was conducted at the University of Pennsylvania, Department of Physical Medicine and Rehabilitation. NBA and WNBA players with an Achilles tendon rupture from 1990 to 2020 were identified. Only elite players, indicated by an average player efficiency rating (PER) of >15 in either of the three seasons pre/post-injury, were included. The average PER, offensive rating, defensive rating, and usage percentage were compared in the three seasons pre- and post-injury. Results Eighteen players met the inclusion criteria, and nine each were classified as dominant and non-dominant Achilles tendon ruptures based on their primary shooting hand. There was no significant difference between the dominant and non-dominant rupture groups in any outcomes pre-injury, including age. The non-dominant cohort had a significant decline in PER (20.04 vs. 14.16; p < 0.001) and offensive rating (110.33 vs. 101.56; p = 0.004) post-injury. There was no significant difference observed post-injury in defensive rating or usage percentage. The dominant cohort had no significant difference in any outcomes post-injury, returning to the same level of play as pre-injury. Despite no difference existing between the groups at baseline, the dominant group performed significantly better post-rupture with regard to PER (19.56 vs. 14.16; p < 0.001) and offensive rating (114.00 vs. 101.56; p < 0.001) versus the non-dominant group. Conclusion Elite NBA and WNBA players with dominant Achilles tendon ruptures had no change in performance post-injury, returning to the same level of production as pre-injury. Post-rupture, they demonstrated notably superior outcomes versus the non-dominant group with regard to PER and offensive rating. The non-dominant rupture group experienced the same decline in PER and offensive rating post-injury observed in previous studies. The data indicate that elite NBA and WNBA players with a dominant Achilles tendon rupture have a much more favorable recovery post-injury and are able to return to the same level of performance.

Acute effects of muscle mechanical properties after 2000-m rowing in young male rowers

Background

The mechanical properties of muscles, such as changes in muscle tone and stiffness, are related to sports performance and injuries. Rowers are at increased risk of muscle fatigue and injury during high-repetition and heavy-load cyclic muscle actions. In view of this, the aim of the present study was to investigate the acute effect on muscle tone and stiffness, as well as bilateral muscle asymmetry, in high school rowers after a 2000-meter rowing ergometer test.

Methods

Twelve young male rowers (age = 17.1 ± 0.9 years, body weight = 73.5 ± 9.7 kg) were included in the study. The data of muscle tone (frequency) and stiffness of the posterior deltoids (PD), latissimus dorsi (LD), and rectus femoris (RF) (dominant and non-dominant side) before and after a 2000-m rowing ergometer test were collected using a handheld MyotonPRO device.

Results

After the rowing ergometer test, the muscle tone of dominant side PD, LD, and RF were significantly increased (p < 0.05). On the other hand, the muscle stiffness of the non-dominant side LD and RF, as well as the dominant side PD, LD, and RF were significantly increased after the rowing ergometer test (p < 0.05). The muscle tone and stiffness results showed that the dominant side PD, LD, and RF were all significantly higher than the non-dominant side after the rowing ergometer test (p < 0.05), where bilateral PD and RF exhibits moderate asymmetry (5% < symmetry index < 10%).

Conclusions

After a high-intensity and high-load 2000-m rowing ergometer test, PD, LD, and RF showed increases in muscle tone and stiffness, as well as changes in the symmetry of bilateral muscle mechanical properties.

Effect of double rocking jump rope training on lower limb muscle strength of badminton players

BACKGROUND

Double rocking jump rope training can effectively enhance physical recovery, adaptability to exercise load, and lower limb muscle strength of badminton players in sports colleges, thus offering valuable insights for improving training methods in sports colleges and universities.

OBJECTIVE

To investigate the effect of double rocking jump rope training on the lower limb muscle strength of badminton players specializing in badminton in sports colleges.

METHODS

An experimental study was conducted through a ten-week teaching intervention experiment with badminton players. Relevant heart rate indexes and badminton related lower limb muscle strength indexes were measured before and after the experiment. The data of the measured relevant indexes were statistically and analytically analyzed. At the end of the experiment, the physical recovery level and the heart's adaptability to the exercise load of the control group were improved, and the lower limb muscle strength test indexes and sports performance were better than before the experiment. In the experimental group, badminton players' physical function, anaerobic metabolism of the body and other aspects also improved.

RESULTS

The physical function of the experimental group of badminton players, the energy supply capacity of the body anaerobic metabolism and aerobic work capacity all have an enhancement effect, enabling badminton players to adapt to large exercise loads quickly and improve the recovery rate of physical fitness.

CONCLUSION

The introduction of double rocking jump rope into badminton training classes in sports colleges and universities as a means of lower limb muscle strength training is conducive to improving the level of lower limb muscle strength of special badminton players, enriching the teaching and training means of lower limb muscle strength in sports colleges and universities, and broadening the research field of lower limb muscle strength in badminton in sports colleges and universities.

Between-sexes differences in lumbopelvic muscle mechanical properties of non-climacteric adults: a cross-sectional design

The lumbopelvic muscle mechanical properties (MMPs) are clinically relevant, but their dependence on sex remains unknown. Therefore, this study aimed to identify if lumbopelvic MMPs depend on the sex in a young adult population. Thirty-five healthy nulliparous women and 35 healthy men were analyzed (age range: 18-50). Lumbopelvic MMPs, that is, tone, stiffness, elasticity, relaxation and creep, assessed with MyotonPRO®, and pelvic floor (PF) health questionnaires were compared between-sexes. Intra-group correlations between sociodemographic and clinical data, and MMPs were also determined. The MMPs of PF were different between healthy non-climacteric adults of both sexes, with women showing higher values of tone and stiffness and lower values of elasticity and viscoelastic properties than men (in all cases, p < 0.03). At lumbar level, tone and stiffness were higher for men at both sides (in all cases, p < 0.04), and relaxation was lower at left side (p = 0.02). The MMPs showed few correlations with sociodemographic data within women. However, within males, there were positive correlations for PF stiffness and viscoelastic parameters with age, BMI and function (0.334 < r < 0.591) and, at lumbar level, negative correlations for tone and stiffness ( - 0.385 < r < -0.590) and positive correlations for viscoelastic properties (0.564 < r < 0.719), with BMI. This indicated that between-sexes differences of lumbopelvic MMPs depend on the specific location of assessment in healthy non-obese young individuals. Women show higher tone and stiffness and lower elasticity and viscoelasticity than men, at PF level.

In Achilles Tendinopathy the Symptomatic Tendon Differs from the Asymptomatic Tendon While Exercise Therapy Has Little Effect on Asymmetries-An Ancillary Analysis of Data from a Controlled Clinical Trial

BACKGROUND

As inter-limb asymmetries can be associated with higher injury risk, we aimed to investigate their role in Achilles tendinopathy patients.

METHODS

In Achilles tendinopathy patients (n = 41), we assessed inter-limb asymmetries of mechanical, material, and morphological musculoskeletal properties and function and how those were affected by 12 weeks of exercise intervention (high-load protocol, n = 13; Alfredson protocol, n = 11). Moreover, we assessed whether asymmetry reductions correlated with improved Patient-Reported Outcomes (VISA-A score).

RESULTS

At baseline, tendinopathic tendons demonstrated lower tendon force (p = 0.017), lower tendon stress (p < 0.0001), larger tendon cross-sectional area (CSA) (p < 0.001), and increased intratendinous (p = 0.042) and tendon overall (p = 0.021) vascularization. For the high-load group, PRE-to-POST asymmetry comparisons revealed an asymmetry increase for the counter-movement jump (CMJ) (p = 0.034) and PRE-to-POST VISA-A score improvements correlated with CSA asymmetry reductions (p = 0.024). Within the Alfredson group, PRE-to-POST VISA-A score improvements correlated with CMJ asymmetry reductions (p = 0.044) and tendon stiffness asymmetry increases (p = 0.037). POST-to-POST in-between group comparisons revealed lower asymmetry in the high-load group for tendon elongation (p = 0.021) and tendon strain (p = 0.026).

CONCLUSIONS

The tendinopathic limb differs from the asymptomatic limb while therapeutic exercise interventions have little effect on asymmetries. Asymmetry reductions are not necessarily associated with tendon health improvements.

Effect of balance training on footwork performance in badminton: An interventional study

Badminton is a racket sport that requires a wide variety of proficient postural changes and moves including jumps, lunges, quick changes in direction, and rapid arm movements. Efficient movement in badminton court entails reaching the shuttlecock in as few steps as possible while maintaining good balance. Balance training is an unexplored component in badminton training protocol, though balance is important in injury prevention and performance enhancement. We aimed to investigate the effectiveness of balance training on sport-specific footwork performance of school-level competitive badminton players. We conducted a controlled trial involving 20 male badminton players (age 12.85±0.67 years). Participants were stratified according to their level of performance in the game, and payers from each stratum were randomly assigned to control and intervention groups. The control group (n = 8) engaged in 2 hours of ordinary badminton training, whereas the intervention group (n = 12) underwent 30 minutes of balance training followed by 1 hour and 30 minutes of ordinary badminton training, 2 days per week for 8 weeks. We tested the participants at baseline and after 8 weeks for static balance (Unipedal Stance Test), dynamic balance (Star Excursion Balance Test) and sport-specific footwork performance (shuttle run time and push-off times during stroke-play). On pre- vs. post-intervention comparisons, both groups improved in static balance (eyes opened) (p<0.05), but only the intervention group improved in dynamic balance (p = 0.036) and shuttle-run time (p = 0.020). The intervention group also improved push-off times for front forehand (p = 0.045), side forehand (p = 0.029) and rear around-the-head shots (p = 0.041). These improvements in push-off times varied between 19-36% of the baseline. None of the footwork performance measures significantly improved in the control group. Our findings indicate that incorporating a 30-minute balance training program into a regular training schedule improves dynamic balance, and on-court sport-specific footwork performance in adolescent competitive badminton players, after 8 weeks of training.

Does Mobility of the Ankle Joint Depends on Length of the Free Part of the Achilles Tendon?

The aim of our study was to evaluate whether the length of the free part of the Achilles tendon affects the mobility of the ankle joint in active motion without a load, as well as in functional motion with a body-weight load. We examined 36 healthy people, aged 21 to 30 years, and divided them into two groups: 1 (n = 15)—participants with a normal range of dorsiflexion in the ankle joint (20° or more), and 2 (n = 21)—participants with a reduced range of dorsiflexion in the ankle joint (below 20°). The length of the free part of the Achilles tendon was measured using ultrasonography. Ankle joint range of dorsiflexion was assessed, and a weight-bearing lunge test (WBLT) was conducted. Group 1 performed the WBLT better and demonstrated significantly greater Achilles tendon length compared to Group 2. A moderate, significant correlation was observed between ankle joint range of dorsiflexion and Achilles tendon length (r = 0.53, p < 0.05); between WBLT and Achilles tendon length (r = 0.61, p < 0.05); as well as between ankle joint range of dorsiflexion and WBLT (r = 0.63, p < 0.05). Thus, we can suggest that both the length of the tendon (measured by USG) and the ankle range of motion under a body-weight load (measured by WBLT) are good indicators regarding the range of foot dorsiflexion, but only up to specific values (6 cm of tendon length and 11 cm of WBLT reach). Therefore, Achilles tendon length, e.g., after injury and during tendon healing, may be monitored using the method of ultrasound imaging presented in this study.

Asymmetries of the Muscle Mechanical Properties of the Pelvic Floor in Nulliparous and Multiparous Women, and Men: A Cross-Sectional Study

This study aimed to identify if the muscle mechanical properties (MMPs) of both sides of pelvic floor muscles (PFMs) are symmetrical in different populations of both sexes. Between-sides comparisons of MMPs of PFMs, assessed with manual myotonometry, were performed in three groups, with 31 subjects each, composed of healthy nulliparous women (without any type of delivery or pregnancy), multiparous women (with at least two vaginal deliveries), and healthy adult men. Intra-group correlations between MMPs and age, body mass index (BMI), or clinical state of pelvic floor were also obtained. The nulliparous women and the men showed no between-sides differences in any MMP of PFMs. However, the multiparous women showed that the right side displayed less frequency (−0.65 Hz, 95% CI = −1.01, −0.20) and decrement (0.5, 95% CI = 0.11, 0.01), and more relaxation (1.00 ms, 95% CI = 0.47, 1.54) and creep (0.07 De, 95% CI = 0.03, 0.11), than the left side. Further, MMPs were related to age, sex, and BMI, also depending on the population, with the multiparous women being the only group with some between-sides asymmetries, which in this case were positive and of fair intensity for the left side of the PFMs, between BMI, and frequency and stiffness (rho Spearman coefficient: 0.365 and 0.366, respectively). The symmetry of MMPs of the PFMs could depend on the subject’s condition. Multiparous women show a higher tendency to asymmetries than nulliparous women and men, which should be considered in research and clinical settings.

CARACTERÍSTICAS DEL TENDÓN ROTULIANO Y DE AQUILES EN JUGADORES SENIOR DE BÁDMINTON

Los objetivos del estudio fueron describir las propiedades estructurales y mecánicas de los tendones rotuliano y de Aquiles en jugadores senior (>35 años) de bádminton y detectar posibles asimetrías entre el lado dominante y no dominante. La muestra estuvo compuesta por 206 jugadores senior de bádminton (Edad: 52.2±9.6 años) que participaron en el campeonato de Europa Senior en 2018. Se evaluaron las propiedades estructurales (grosor, anchura y área de sección transversal) por medio de un ecógrafo Logiq® S8 y las propiedades mecánicas (elasticidad, tono, rigidez e índice de elastografía) con miotonometría y sonoelastografía de los tendones rotuliano y de Aquiles. Los resultados mostraron que fueron mayores el grosor (5.34±19.90%, p = 0.027) y la anchura (1.57±8.52%, p=0.036) en el tendón de Aquiles no dominante mientras que el tendón rotuliano dominante mostró unos valores mayores para el tono (2.09±12.96%, p=0.002) y para la rigidez (4.41±21.11%, p=0.002) respecto al no dominante.

The Effects of Eccentric Contraction Execution Time on the Properties of the Patellar Tendon

The purpose of this study was to assess the effects of eccentric contraction execution time on the morphological and elastic properties of the patellar tendon (PT) in a six-week, single-leg decline squat (SLDS) exercise training program. In addition, the effects of a six-week detraining period on the same variables were evaluated. Fifty participants were randomized into the control group (CG; n = 15), experimental group 1 (EG6s; n = 17; eccentric contraction execution time = 6 s) and experimental group 2 (EG3s; n = 18; eccentric contraction execution time = 3 s). The thickness and elastographic index (EI) in different regions of interest (ROIs) in the PT were measured after 6 weeks of eccentric training using the single-leg decline squat exercise (three sessions per week, 80% of the eccentric one-repetition maximum) and after 6 weeks of detraining. There was an increase in the thickness of the PT in the different ROIs analyzed in both experimental groups at the end of the training period. Especially worth noting was the increase in the thickness of the PT at the proximal level in EG3s (p = 0.001), and the increase at the distal level in EG6s (p = 0.001). On the other hand, there was a reduction in EI in EG6S at the end of the intervention program (p = 0.021), and both experimental groups increased EI in the three regions of interest analyzed after the detraining period (p < 0.01). In conclusion, the execution time of the eccentric contraction in the SLDS exercise determines the anatomical level of the morphological adaptations in the PT. These morphological adaptations are lost after 6 weeks of detraining, producing an increase in tendon stiffness.

Residual force enhancement is affected more by quadriceps muscle length than stretch amplitude

Little is known about how muscle length affects residual force enhancement (rFE) in humans. We therefore investigated rFE at short, long, and very long muscle lengths within the human quadriceps and patellar tendon (PT) using conventional dynamometry with motion capture (rFE_TQ) and a new, non-invasive shear-wave tensiometry technique (rFE_WS). Eleven healthy male participants performed submaximal (50% max.) EMG-matched fixed-end reference and stretch-hold contractions across these muscle lengths while muscle fascicle length changes of the vastus lateralis (VL) were captured using B-mode ultrasound. We found significant rFE_TQ at long (7±5%) and very long (12±8%), but not short (2±5%) muscle lengths, whereas rFE_WS was only significant at the very long (38±27%), but not short (8±12%) or long (6±10%) muscle lengths. We also found significant relationships between VL fascicle length and rFE_TQ (r=0.63, p=0.001) and rFE_WS (r=0.52, p=0.017), but relationships were not significant between VL fascicle stretch amplitude and rFE_TQ (r=0.33, p=0.126) or rFE_WS (r=0.29, p=0.201). Squared PT shear-wave-speed-angle relationships did not agree with estimated PT force-angle relationships, which indicates that estimating PT loads from shear-wave tensiometry might be inaccurate. We conclude that increasing muscle length rather than stretch amplitude contributes more to rFE during submaximal voluntary contractions of the human quadriceps.

Effects of Plyometric Training on Lower Body Muscle Architecture, Tendon Structure, Stiffness and Physical Performance: A Systematic Review and Meta-analysis

BACKGROUND

Plyometric training (PT) has been widely studied in sport science. However, there is no review that determines the impact of PT on the structural variables and mechanical properties of the lower limbs and physical performance.

OBJECTIVE

The aim of this systematic review and meta-analysis was to determine the effects of PT on lower body muscle architecture, tendon structure, stiffness and physical performance.

METHODS

Five electronic databases were analysed. The inclusion criteria were: (1) Availability in English; (2) Experimental studies that included a PT of at least eight sessions; and (3) Healthy adults subjects. Four meta-analyses were performed using Review Manager software: (1) muscle architecture; (2) tendon structure; (3) muscle and tendon stiffness; (4) physical performance.

RESULTS

From 1008 search records, 32 studies were eligible for meta-analysis. Muscle architecture meta-analysis found a moderate effect of PT on muscle thickness (Standard Mean Difference (SMD): 0.59; [95% Confidence Interval (CI) 0.47, 0.71]) and fascicle length (SMD: 0.51; [95% CI 0.26, 0.76]), and a small effect of PT on pennation angle (SMD: 0.29; [95% CI 0.02, 0.57]). The meta-analysis found a moderate effect of PT on tendon stiffness (SMD: 0.55; [95% CI 0.28, 0.82]). The lower body physical performance meta-analysis found a moderate effect of PT on jumping (SMD: 0.61; [95% CI 0.47, 0.74]) and strength (SMD: 0.57; [95% CI 0.42, 0.73]).

CONCLUSION

PT increased the thickness, pennation angle and fascicle length of the evaluated muscles. In addition, plyometrics is an effective tool for increasing tendon stiffness and improving jump and strength performance of the lower body.

Recognition of Badminton Shot Action Based on the Improved Hidden Markov Model

In recent years, with the rapid development of sports, the number of people playing various sports is increasing day by day. Among them, badminton has become one of the most popular sports because of the advantages of fewer restrictions on the field and ease of learning. This paper develops a wearable sports activity classification system for accurately recognizing badminton actions. A single acceleration sensor fixed on the end of the badminton racket handle is used to collect the data of the badminton action. The sliding window segmentation technique is used to extract the hitting signal. An improved hidden Markov model (HMM) is developed to identify standard 10 badminton strokes. These include services, forehand chop, backhand chop the goal, the forehand and backhand, forehand drive, backhand push the ball, forehand to pick, pick the ball backhand, and forehand. The experimental results show that the model designed can recognize ten standard strokes in real time. Compared with the traditional HMM, the average recognition rate of the improved HMM is improved by 7.3%. The comprehensive recognition rate of the final strokes can reach up to 95%. Therefore, this model can be used to improve the competitive level of badminton players.

Morphology of the Patellar Tendon and the Contractility Response of the Quadriceps: Symmetry and Gender Analysis

The purpose of the study was to describe the differences between the dominant and non-dominant leg regarding contractility response and quadriceps strength and the morphology and stiffness of the patellar tendon (PT) in a group of physically active men and women. Fifty physically active subjects (36 men and 14 women) were evaluated for morphology and stiffness of the PT, contractility response of the rectus femoris of the quadriceps, isometric strength of the quadriceps and hamstrings, and isokinetic strength (concentric and eccentric) at 60°/s of the knee extensors. The measurements were made on the subject's dominant and non-dominant leg. The men showed a greater thickness of the PT in both legs compared to the women. Regarding the contractility response, the women recorded a 10.1 ± 16.2% (p = 0.038) greater contraction time (ct) in the dominant versus the non-dominant leg and the men recorded 11.9% (p = 0.040) higher values in the dominant leg compared to the women. In all the absolute strength measurements the men recorded higher values (p < 0.05) than the women, however, when the values were normalised with respect to the muscle mass of the leg these differences disappeared. The dominant leg showed values of isometric strength and eccentric strength at 60°/s (p < 0.05) greater than the non-dominant leg. The reference values provided in this study of the knee extensors and PT may be useful for detecting possible muscular or tendinous anomalies.

Does a Loaded Warm-Up Influence Jump Asymmetry and Badminton-Specific Change of Direction Performance?

PURPOSE

Previously, it has been shown that loaded warm-up (LWU) can improve change-of-direction speed (CODS) in professional badminton players. However, the effect of asymmetry on CODS in badminton players and the influence of LWU on asymmetry has not been examined.

METHODS

A total of 21 amateur badminton players (age 29.5 [8.4] y, playing experience 8.4 [4.2] y) completed 2 trials. In the first, they performed a control warm-up. In the second, they performed the same warm-up but with 3 exercises loaded with a weight vest (LWU). Following both warm-ups, players completed single-leg countermovement jump and badminton-specific CODS tests.

RESULTS

No significant differences between control warm-up and LWU were observed for CODS, single-leg countermovement jump, or single-leg countermovement jump asymmetry. However, small effect sizes suggested faster CODS (mean difference: -5%; d = -0.32) and lower asymmetries (mean difference: -3%; d = -0.39) following LWU. Five players (24%) experienced CODS improvements greater than the minimum detectable change while 2 (10%) responded negatively. Asymmetry was not correlated with CODS following control warm-up (ρ = .079; P = .733) but was negatively associated with CODS after LWU (ρ = -.491; P = .035).

CONCLUSION

LWU may prove a strategy to trial on an individual basis, but generic recommendations should not be applied.

Benefits of Regular Table Tennis Practice in Body Composition and Physical Fitness Compared to Physically Active Children Aged 10-11 Years

The aim of this study was to identify the differences in body composition and physical fitness between children who played table tennis regularly during a two-year period compared to physically active children who were not engaged in a regular activity. Three hundred seventy-four children aged 10 to 11 years were divided into two groups: table tennis players (n = 109 boys and 73 girls) and physically active group (n = 88 boys and 104 girls). Anthropometric analysis included body mass index, skinfolds, perimeters and bone diameters. Somatotype and body composition were determined according to age-specific equations. Physical fitness assessment included hand grip dynamometry (strength), sit-and-reach test (range of movement) and maximal multistage 20 m shuttle run test (cardiovascular fitness). The result show that children who regularly played table tennis had greater bone development and superior physical fitness compared to those who were physically active but not engaged in a regular physical activity. This is the largest study to date presenting data about the potential of table tennis to benefit health in children. These results constitute an important first step in clarifying the effectiveness of table tennis as a health-promotion strategy to encourage children to undertake regular physical activity and limit sedentary behavior.

Correlation between maximal radial muscle displacement and stiffness in gastrocnemius muscle

OBJECTIVE

Tensiomyography (TMG) and myotonometry (MMT) are two novel technologies that measure neuromuscular properties. These two devices measure the stiffness of the soft tissue as well as other variables. The aim of this study is to analyze if there is any correlation between maximal radial displacement (Dm) and Stiffness in the medial and lateral gastrocnemius muscles.

APPROACH

An observational study was carried out in both of the limbs of 154 young adults (n = 154). The TMG and MMT neuromuscular response was measured in gastrocnemius medial and lateral muscles. Correlation coefficients were calculated to observe if there were any relationships between Dm and Stiffness. Differences between the dominant and the non-dominant sides and gender were assessed.

MAIN RESULTS

Negative correlations between Dm versus Stiffness were found for the lateral (r = -0.278 and rho = -0.248) and medial gastrocnemius (r = -0.207 and rho = -0.163) in both dominant and non-dominant limbs respectively.

SIGNIFICANCE

A weak correlation between Dm and Stiffness may indicate that they assess different aspects of neuromuscular function. The MMT and TMG are independent tools, and their values cannot be extrapolated when assessing muscular stiffness. There might be some other factors that influence in this relationship; therefore, more studies are needed in order to better understand the correlation.

Effects of Eccentric Single-Leg Decline Squat Exercise on the Morphological and Structural Properties of the Vastus Lateralis and Patellar Tendon

The purpose was to examine the effect of 6-week eccentric single-leg decline squat (SLDSe) training with two technical execution times (3 s or 6 s) on changes related to the structural properties of the vastus lateralis (VL) and patellar tendon (PT). Thirty-six physical active volunteers were randomly divided into three groups: control group (CG, n = 13, age = 20.8 ± 1.9 years, no intervention program), experimental group 1 (EG1, n = 11, age = 21.6 ± 2.5 years, execution time = 6 s) and experimental group 2 (EG2, n = 12, 21.1 ± 1.2 years, execution time = 3 s). Participants completed a 6-week SLDSe training program (80% of 1-RM) three days a week. The structural characteristics of the VL and the PT were measured with ultrasonography before and after 6-week SLDSe training and after 6 weeks of de-training. Our results indicate that EG1 increased ≈21.8% the thickness of the PT and EG2 increased ≈15.7% the thickness of the VL after the 6-week intervention program. EG1 and EG2 showed greater values (p < 0.05) of lean mass and lower values (p < 0.05) of fat percentage on the thigh after the intervention program. In conclusion, the SLDSe training carried out with the execution time of 6 s had greater effects on the structural and elastic properties of the PT, and the exercise with the execution time of 3 s caused greater structural adaptations in the VL musculature.

Stiffness of the Gastrocnemius-Achilles Tendon Complex Between Amateur Basketball Players and the Non-athletic General Population

Muscle and tendon stiffness are related to sports performance, tendinopathy, and tendon degeneration. However, the effects of habitual loading on muscle and tendon mechanical properties are unclear. Using amateur basketball players as examples, we investigated the effects of mechanical loading on the stiffness of the gastrocnemius–Achilles tendon (AT) complex in non-dominant and dominant lower limbs. Then, we evaluated the correlation between gastrocnemius and AT stiffness. Forty participants (20 amateur basketball players; 20 normal non-athletic persons) were recruited for this study. Stiffness of the gastrocnemius–AT complex was assessed using MyotonPRO at neutral position and 10° dorsiflexion of the ankle joint in participants from amateur basketball players and the non-athletic general population. Our results showed a greater stiffness of the gastrocnemius–AT complex in amateur basketball players than that in healthy non-athletic subjects at neutral position and 10° dorsiflexion of the ankle joint (P < 0.05). No significant difference in stiffness was found between the non-dominant and dominant lower limbs either in amateur basketball players or in generally healthy subjects (P > 0.05). A significant positive correlation was obtained between stiffness of the AT and medial gastrocnemius (MG) in amateur basketball players (neutral position: r = 0.726 and P = 0.001; dorsiflexion 10°: r = 0.687 and P = 0.001). The amateur basketball players exhibit significantly higher stiffness value in Achilles and gastrocnemius. This is possibly caused by repeated training effects. The symmetric stiffness of the AT and gastrocnemius exists both in amateur basketball players and generally healthy subjects. A significant correlation between the AT and the MG was found in amateur basketball players.

Influence of Badminton Practice on Age-Related Changes in Patellar and Achilles Tendons

Regular sport practice could prevent age-related changes in tendinous tissues. The purpose of the study was to investigate the effect of regular badminton practice on patellar and Achilles tendon mechanical properties in senior competitive badminton players (>35 years old) and to compare the results with physically active people matched by age. One hundred ninety-two badminton players and 193 physically active people were divided by age into four groups, between 35 and 44 (U45), between 45 and 54 (U55), between 55 and 64 (U65), and over 65 (O65) years old. A LogiqS8 transducer in elastography mode and a MyotonPRO myotonometer were used to assess patellar and Achilles mechanical properties. Achilles tendon stiffness was higher in the control group than the badminton players for the U45, U55, and O65 age groups (p < .01). Also, the elastography index was higher in the control group than the badminton players for the U45, U55, U65, and O65 age groups (p < .05). In conclusion, regular badminton practice could prevent the decline in mechanical properties of the patellar and Achilles tendons.

Phantom material testing indicates that the mechanical properties, geometrical dimensions, and tensional state of tendons affect oscillation-based measurements

OBJECTIVE

There is an increasing interest in the application of oscillation-based measurement techniques to evaluate the mechanical stiffness of healthy and diseased tendons. These techniques measure the stiffness of a tendon indirectly by registering the oscillation response of a tendon to an external mechanical impulse. Although these measurement techniques seem to be comparatively easy and time-saving, their applicability is implicitly limited by their indirect measurement principle.

APPROACH

In this study, we aim to find evidence that the oscillation response of a tendon to an external mechanical impulse is not only affected by the stiffness of a tendon but also by the tendons' cross-sectional area (CSA), length, and tension. Therefore, we reviewed the current literature on oscillation-based techniques that measure in vivo tendon properties. Further, a phantom material was used to mimic the nature of tendons and to test the impact of four factors on oscillation-based measurements.

MAIN RESULTS

Our results indicate that the mechanical properties, geometrical dimensions (length and CSA), and tensional state affect oscillation-based measures. Surprisingly, most studies on tendon behavior often exclusively associate their oscillation-based measurements with the mechanical stiffness of a tendon.

SIGNIFICANCE

While this narrow perspective bears the risk of misinterpretation or false implications, a broader understanding of oscillation-based measurements has the potential to shed new light on the interaction of muscles and tendons in vivo.

High vibration frequency of soft tissue occurs during gait in power-trained athletes

Muscles serve as a critical regulator of locomotion and damping, resulting in changes of soft tissue vibration. However, whether muscle fibre compositions of different individuals will cause different extents of soft tissue vibration during gait is unclear. Therefore, this study investigated the differences in lower extremity vibration frequencies among power-trained and non-power-trained athletes during walking and running. Twelve weightlifting athletes were assigned to the power-trained group and twelve recreational runners were assigned to the non-power-trained group. Accelerometers were used to detect soft tissue compartment vibration frequencies of the rectus femoris (RF) and gastrocnemius medialis (GMS) during walking and running. Results indicated that power-trained athletes, as compared to the non-power-trained, induced significantly (p < 0.05) higher vibration frequencies in their soft tissue compartments during walking and running. This suggests that power-trained athletes, who have higher ratios of fatigable fast-twitch muscle fibres, may have induced higher soft tissue compartment vibration frequencies. As a result, there is a likelihood that power-trained athletes may recruit more fatigable fast-twitch muscle fibres during muscle tuning, causing dysfunctions during prolonged exercises.