OSIC is the regional sports information centre that's headquartered at The University of the South Pacific and funded by the Oceania National Olympic Committees.
Oceania Highlights
13 November, 2020
Bula Vinaka,
We have some more sports research for you this week with table tennis, taekwondo, tennis, and volleyball research.
At the end of the series we will send out research that we missed. All articles are open source and free. OSIC will continue with the series next week.
If you have any questions, please contact me at +679-323-1958 or osic@onoc.org.fj.
Martin V Burrows Jr.
Coordinator
Oceania Sport Information Centre
Ball Tracking and Trajectory Prediction for Table-Tennis Robots (2020)
Sports robots have become a popular research topic in recent years. For table-tennis robots, ball tracking and trajectory prediction are the most important technologies. Several methods were developed in previous research efforts, and they can be divided into two categories: physical models and machine learning. The former use algorithms that consider gravity, air resistance, the Magnus effect, and elastic collision. However, estimating these external forces require high sampling frequencies that can only be achieved with high-efficiency imaging equipment. This study thus employed machine learning to learn the flight trajectories of ping-pong balls, which consist of two parabolic trajectories: one beginning at the serving point and ending at the landing point on the table, and the other beginning at the landing point and ending at the striking point of the robot. We established two artificial neural networks to learn these two trajectories. We conducted a simulation experiment using 200 real-world trajectories as training data. The mean errors of the proposed dual-network method and a single-network model were 39.6 mm and 42.9 mm, respectively. The results indicate that the prediction performance of the proposed dual-network method is better than that of the single-network approach. We also used the physical model to generate 330 trajectories for training and the simulation test results show that the trained model achieved a success rate of 97% out of 30 attempts, which was higher than the success rate of 70% obtained by the physical model. A physical experiment presented a mean error and standard deviation of 36.6 mm and 18.8 mm, respectively. The results also show that even without the time stamps, the proposed method maintains its prediction performance with the additional advantages of 15% fewer parameters in the overall network and 54% shorter training time.
Effect of Table Tennis Trainings on Biomotor Capacities in Boys (2017)
The aim of this study is to investigate whether the biomotor capacities of boys doing table tennis trainings are affected. A total of 40 students, as randomly selected 20 test groups and 20 control groups at an age range of 10-12 participated in the research. Statistical analysis of data was performed using Statistic Package for Social Science (SPSS) 20.0 statistical package program. Mann Whitney U Test was used in comparison of two variable groups, and the result being p < 0.05 was considered significant when examined statistically. In pre-test and final-test comparisons of the subjects, it was detected that the statistical differences between flexibility, vertical jump, standing long jump, 30 m sprint, anaerobic strength, maximal oxygen capacity (MaxVO2) right and left hand grip strength, visual and audio reaction times, resting heart rate, and forced expiration volume (FEV) and FEV1 measurements were significant in favor of the test group (p < 0.05), while there was no statistically significant differences between the two groups in height, body weight, body fat percentage, body mass index, systolic and diastolic blood pressure, and vital capacity (VC) and forced vital capacity (FVC) values (p > 0.05). At the end of this study, it was observed that table tennis trainings provided positive contributions to biomotor capacities in boys of the group aged 10-12.
Gender Differences in Kinematic Parameters of Topspin Forehand and Backhand in Table Tennis (2020)
Background: The identification of gender differences in kinematics and coordination of movement in different body segments in sports may improve the training process by emphasizing the necessity of its differentiation, and consequently individualization, developing, and improving the technique in women and men. Indicating differences can also help in determining the risk of injury in order to prevent from them by diversifying training programs. However, there is no information regarding this problem in the existing literature pertaining to table tennis. Therefore, the aim of the study was to evaluate the differences in the values of selected angular and kinematic parameters during topspin forehand and topspin backhand shots between male and female table tennis players. Methods: Six male and six female advanced table tennis players performed topspin forehand and topspin backhand shots, both receiving a backspin ball. The angular parameters in four events (ready position, backswing, maximum acceleration, and forward) at chosen joints as well as the maximal acceleration of the playing hand were measured, using the myoMotion system, and were compared between male and female players. Results: Significant differences (p ≤ 0.05) were found in the magnitude of angular parameters and maximum hand acceleration between men and women. The movement pattern of topspin strokes performed by men takes into account, more than that in the case of women, movements that use large muscle groups and large joints (hip joints, trunk joints, shoulder joints in extension, and flexion). The difference in the values of maximal acceleration reached almost 50 m/s2 in topspin forehand (p < 0.01) and 20 m/s2 in backhand (p < 0.01). Conclusions: Differentiation of movement patterns can be a manifestation of movement optimization due to anthropological differences and limitations. The differences in the values of maximal acceleration suggest that women could use both sides to perform a topspin attack against the backspin ball, while men should seek opportunities to make a stronger shot with a forehand topspin.
Habitual and Ready Positions in Female Table Tennis Players and their Relation to the Prevalence of Back Pain (2020)
The current body of knowledge shows that there is very little research into the occurrence and scale of asymmetry or postural defects in table tennis. It is interesting which regions of the spine are exposed to the greatest changes in the shape of its curvatures and whether the asymmetrical position of the shoulder and pelvic girdles in table tennis players changes when adopting the ready position. Consequently, can overload occur in certain parts of the spine and can the asymmetry deepen as a response of adopting this position? The reply to these questions may be an indication of the need for appropriate compensatory or corrective measures. Therefore, the aim of the study was to evaluate the effect of body position during play on the change in the shape of anterior–posterior spinal curvatures and trunk asymmetry in table tennis players
The Impact of Eye-closed and Weighted Multi-ball Training on the Improvement of the Stroke Effect of Adolescent Table Tennis Players (2020)
This paper investigated the impact of eye-closed and weighted training (EWMT) on the stroke effect of adolescent table tennis players. Forty-eight adolescent table tennis players were randomly selected from the China Table Tennis College and were divided into two groups as 1) the experimental group (EG, n = 24) in which they engaged in multi-ball exercise with eye-closed and weighted swing for 10 weeks, and 2) the control group (CG, n = 24) in which they received a normal training without eye-closed and weighted swing intervention. The stroke effect was assessed by three outcome measures: accuracy, stability, and ball speed. Results showed that 1) both the traditional training method and EWMT can improve the stroke effect of adolescent table tennis players. 2) In terms of accuracy, the number of stroke in the corner area was significantly different between EG and CG after the experiment (p = 0.022, p < 0.001, respectively). 3) In terms of stroke stability, there was a significant difference in the number of net ball strokes between EG and CG after the experiment (p = 0.014). 4) In terms of ball speed, there was no significant difference between EG and CG after the experiment (p = 0.871). 5) After EWMT, the stroke stability of backspin had more significant improvement than that of topspin. Thus, compared with the traditional training method, the EWMT method can improve the stroke effect of adolescent table tennis players in terms of accuracy and stability more significantly; the EWMT method can improve the stroke effect of backspin more significantly than that of topspin in terms of stability.
The Motor and Leisure Time Conditioning of Young Table Tennis Players' Physical Fitness (2020)
The purpose of the study was to assess the association between physical fitness and the lifestyle determinants of elite junior table tennis players. The basic anthropometric characteristics (body height and body weight) were collected of 87 Polish table tennis players (girls, n = 38 and boys, n = 49, at different stages of sport training, targeted and specialized) aged 11-17 years. The level of special fitness tests from the Table Tennis Specific Battery Test were used, assessing reaction speed and displacement speed. All eight International Physical Fitness Test trials were also used to determine the level of general fitness of the participants. Selected questions from the Health Behaviour in School-Aged Children questionnaire were asked to measure factors associated with leisure time. The findings confirm a relationship between sedentary forms of leisure time activity and the training of young players at the targeted stage (Z = -2.93, p = 0.003 school days and Z = -2.12, p = 0.034 days off). Moreover, competitors with longer training experience more often chose active forms of spending free time. Knowledge of the global physical activity undertaken by young athletes during their leisure time provides a better understanding of their individual needs and may help young table tennis players to succeed at a world-class level in the future.
The Relationship Between Stress and Coping in Table Tennis (2017)The aim of this study was to examine the relationship between cognitive competitive anxiety intensity and coping strategies in table tennis players. One hundred and two (102) US competitive table tennis players of age range from 10 to 60 filled out a Revised Competitive State Anxiety Inventory-2 (CSAI-2R, Cox et al., 2003) at least 30 minutes before the start of their tournament match and a Modified Cope questionnaire (MCOPE; Crocker and Graham, 1995) 15 minutes after they finished their match. Our study found significant differences between low and high cognitive competitive anxiety groups with regard to the use of coping strategies. The high cognitive competitive anxiety intensity group used significantly more behavioral disengagement (avoidance coping, p ≤ 0.05), denial coping strategies (emotion focused coping, p ≤ 0.01) compared to the low cognitive anxiety intensity group. Our results suggest that there is some connection between anxiety intensity and coping strategies. If the cognitive anxiety intensity (for example, intensity from worrying) is very high, an athlete might be more likely to use avoidance coping (such as behavioral disengagement) and emotion-focused coping (such as denial and venting of emotions) compared to athletes who have low cognitive competitive anxiety. Furthermore, gender differences in cognitive anxiety and direction were found. Confidence management techniques such as positive self-talk, breathing techniques and visualization should be taught to athletes to assist them in coping with their competitive anxiety better and to enhance their performance.
Using Wearable Inertial Sensors to Estimate Kinematic Parameters and Variability in the Table Tennis Topspin Forehand Stroke (2020)
The study examined kinematic parameters and their inter- and intrasubject variability in the topspin forehand of seven top-level table tennis players. A wireless inertial measurement unit (IMU) system measured the movement of the playing hand to analyze the Ready position, Backswing, and Forward events, and a racket-mounted piezoelectric sensor captured the racket-ball Contact. In a four-phase cycle (Backswing, Hitting, Followthrough, and Back to Ready position), body sensors recorded the cycle and phase duration; angles in the sagittal plane at the shoulder, elbow, and wrist of the playing hand and at the knee joints; and acceleration of the playing hand at the moment of racket-ball contact. The coefficient of variation (CV) was calculated to determine the variability of kinematic parameters within and between players. The observed variability in stroke time duration was low (CV < 20%) indicating constancy. The small-to-medium intraindividual variability of angles (CV < 40%) indicates that each player used a broadly repeatable technique. The large intraindividual variability in movement was probably functional (i.e., motor adjustment and injury avoidance). Interindividual and intraindividual variability of knee and elbow angles was low; wrist extension was the most variable parameter (CV > 40%) for all tasks, and shoulder joint variability was medium-to-large. Variability in hand acceleration was low (CV < 20%). Individual players achieved relatively constant hand acceleration at the moment of contact, possibly because angular changes at one joint (e.g., shoulder) could be compensated for by changes at another (e.g., wrist). These findings can help to guide the teaching-learning process and to individualize the training process.
Taekwondo
Analysis of Injuries in Taekwondo Athletes (2016)
[Purpose] The present study aims to provide fundamental information on injuries in taekwondo by investigating the categories of injuries that occur in taekwondo and determining the locations of these injuries. [Subjects and Methods] The data of 512 taekwondo athletes were collected. The sampling method was convenience sampling along with non-probability sampling extraction methods. Questionnaire forms were used to obtain the data. [Results] The foot, knee, ankle, thigh, and head were most frequently injured while practicing taekwondo, and contusions, strains, and sprains were the main injuries diagnosed. [Conclusion] It is desirable to decrease the possibility of injuries to the lower extremities for extending participation in taekwondo. Other than the lower extremities, injuries of other specific body parts including the head or neck could be important factors limiting the duration of participation. Therefore, it is necessary to cope with these problems before practicing taekwondo.
Comparison of Proprioceptive Training and Muscular Strength Training to Improve Balance Ability of Taekwondo Poomsae Athletes: A Randomized Controlled Trials (2018)
Maintaining balance while performing “Hakdariseogi” in Taekwondo, which involves standing on one leg, is a critical aspect of the Poomsae competition. The purpose of this study was to investigate the effect of proprioceptive training and lower-limb muscular strength training on the balance of Taekwondo Poomsae athletes over a 6-week period. Thirty Taekwondo Poomsae athletes were randomly assigned to three groups, namely, a proprioception training group, a lower-limb muscular strength training group, and a control group. Biomechanics data were collected using eight infrared cameras (Qualysis, Sweden) at 200 Hz and a force plate (Kistler, Switzerland) at 2,000 Hz while the participants performed “Hakdariseogi” before and after the 6-week intervention. Balance and stability variables were calculated using customized MATLAB R2014b software (Mathworks, Inc., USA). The medio-lateral (M/L) center of pressure (CoP) range, M/L CoP mean velocity, antero-posterior (A/P) CoP range, A/P CoP mean velocity, and the vertical ground reaction torque after the training were reduced at P1 in the PG groups (p < 0.05). A decrease in the A/P CoP range, A/P CoP mean velocity, and vertical ground reaction torque after the training were observed at P2 in the PG and SG groups (p < 0.05). The PG exhibited a smaller A/P CoP range and A/P CoP mean velocity, in comparison to CG (p < 0.05). The A/P CoP position at P1 was negatively correlated with the vertical ground reaction torque, A/P CoP range, and A/P CoP mean velocity at P2(r = -0.438, r = -0.626, r = -0.638). Based on the above results, this study determined that both proprioception training and lower-extremity muscle strength training resulted in an improvement of athletic performance. It was also desirable to move the CoP position through conscious effort forward at P2 in order to maintain the crane stance without sway.
Dental Injuries in Taekwondo Athletes Practicing in Saudi Arabia (2017)
Objectives:To assess the incidence and awareness of taekwondo athletes in Saudi Arabia regarding oral and maxillofacial (OMF) injuries and their prevention.
Methods:In this cross-sectional study, an online questionnaire about the incidence and awareness of OMF injuries and their prevention was developed and distributed to taekwondo athletes in Saudi Arabia via their coaches.
Results:Sixty-eight responses were collected. The mean age of the participants was 29.3±9.1 years and 97% of them were males. Most of the participants (83%) believed that they are vulnerable to OMF injuries during practice. Approximately 23% of the participants reported a previous injury of the OMF area, while approximately 56% reported injuries in other areas. Most dental injuries (94%) were tooth fracture or displacement, while 6% were tooth avulsion. Eight participants (12%) were aware of the possibility of returning an avulsed tooth to its socket. More than 50% of those participants had inadequate knowledge on the appropriate storage media for the avulsed tooth or the maximum time allowed to return it to its socket. Eighty-one percent of the participants knew about the mouthguard, while 56% reported that they are actually using one. The most frequently reported barriers for not using a mouthguard during practice were difficulty in practicing with it, not being convinced of its importance, and lack of information where to get one.
Conclusions:Most of the participants are aware of OMF injuries; however, their knowledge and behavior towards preventing and managing them are inadequate.
Identification of Elite Performance Characteristics in a Small Sample of Taekwondo Athletes (2019)
Along with the increasing popularity of taekwondo, there is a need of evidence-based talent identification (TID) and development programs based upon profiles of future elite athletes. This study first aims to investigate the differences between elite and non-elite taekwondo athletes in anthropometry, physical performance and motor coordination. The second aim is to demonstrate the applicability of z-scores in TID research. A total of 98 Taekwondo athletes between 12 and 17 years old were tested using a generic test battery consisting of four anthropometrical (Height, Weight, Fat Percentage, BMI), six physical performance (Sit & Reach, Sprint 5m, Sprint 30m, Counter Movement Jump, Squat Jump, Endurance Shuttle Run) and three motor coordination tests (Moving Sideways, Jumping Sideways, Walking Backwards). Based on the individual success at international competition level, 18 were categorised as elite athletes and 80 were considered as non-elite. T-tests (step 1) on raw test scores and MANOVAs on z-scores (step 2) were conducted to examine differences between the elite and non-elite taekwondo athletes for anthropometry, physical performance and motor coordination tests. Finally, z-scores were reconverted to raw scores to demonstrate practical significance for coaches. Overall, elite taekwondo athletes score better compared to the non-elite group. The MANOVA analysis better scores for elites on fat percentage (-0.55 versus 0.12;p = 0.006), BMI (-0.37 versus 0,08;p = 0.067) sprint speed 30m (-0.48 versus 0.11;p = 0.029), counter movement jump (0.79 versus -0.18;p = 0.000), squat jump (0.42 versus -0.11;p = 0.041), moving sideways (0.79 versus -0.18;p = 0.000) and walking backwards (0.54 versus -0.12;p = 0.006). This study confirms our knowledge on physical profiles of elite taekwondo athletes and expands our knowledge to the domain of motor coordination. This study showed how the z-score method can be used to distinguish between elite and non-elite athletes, the former being low in number by definition.
Pain Perception in Taekwondo: Relationship to Injury, Experience, and Time Loss (2020)
Injury and pain are natural sequela of contact sports. An estimated 8.6 million people are injured per year through sports and recreational activities in the United States 1 . Pain from sports injuries has been discussed in a few studies such as that of soccer, basketball, and rugby, but the vast majority of these studies have discussed pain as it relates to a surgical procedure or rehabilitation 2 3 4 5 6 . Risk factors for pain have been analyzed in several descriptive studies and cohort studies 7 8 9 , but these studies do not discuss an athlete’s perception of pain following different types of acute injury and how it relates to time loss. With increasing concern over re-injury and concussion, there is concern with returning to sport too early before underlying physiological structures have healed.
Taekwondo is a Korean martial art with over 80 million practitioners worldwide 10 . Sparring, a subspecialty of Taekwondo, is a full-contact sport that permits kicks to the head and torso and punches to the torso. World Taekwondo (WT), the regulating organization, requires that competitors wear protective gear to cover the trunk, groin, forearms, shins, gloves, head, and mouth 11 . Competitors are matched by age, rank, and weight and fight three 2-minute bouts per match. There have been numerous studies describing the frequency, severity, type, and location of Taekwondo injuries 11 12 13 . In a meta-analysis, Taekwondo had a competition injury rate of 79.3/1000 athlete-exposures (AE), which is higher than the rate in men’s American football (35.9/1000 AE), soccer (18.8/1000 AE), and hockey (16.3/1000 AE) 11 14 . Moreover, the prevalence of concussion in Taekwondo has been noted to be four-fold higher than American football over a 15-year span (9.4/1000 AE vs. 2.3/1000 AE). For all these injuries, there is no data yet on whether pain or injuries have fully resolved prior to returning to sport. In addition, pain is the body’s failsafe to stop participating in a sport. Certain injuries may have higher time loss than others, yet there is minimal follow-up on these injuries and knowledge as to how pain and injury type relate to time loss.
Taekwondo Anaerobic Intermittent Kick Test: Discriminant Validity and an Update with the Gold-Standard Wingate Test (2020)
The aim of this study was to update the validity of the Taekwondo Anaerobic Intermittent Kick Test compared with the 30-s Wingate anaerobic test as the "Gold-Standard", squat jump and countermovement jump tests. The second objective was to examine whether this new specific test would be able to effectively discriminate between elite taekwondo athletes of different competitive levels. Twenty taekwondo athletes (15 males and 5 females) participated in the validation component, whereas 18 (14 males and 4 females) and 16 (13 males and 3 females) athletes participated in the reliability analysis of the Wingate anaerobic test and jumping tests, respectively. They performed these tests on two separate occasions (i.e., test-retest), in addition to the Taekwondo Anaerobic Intermittent Kick Test. To establish test's discriminatory capability (i.e., construct validity), two subgroups were identified based on their international and national taekwondo performance: 10 elite (8 males and 2 females) and 9 sub-elite (7 males and 2 females) athletes. Wingate anaerobic test and jumping tests performances showed excellent reliability (ICC > 0.90, SEM < 5% for most variables). Significant correlations between Taekwondo Anaerobic Intermittent Kick Test, Wingate anaerobic test, and jumping tests' variables were mostly "large". Elite taekwondo athletes showed greater taekwondo test performances compared with their sub-elite counterparts (p < 0.001). Receiving operating characteristic analysis indicated that the taekwondo specific test was able to effectively discriminate between elite and sub-elite taekwondo athletes. Overall, the findings of the current study support the concurrent validity of the Taekwondo Anaerobic Intermittent Kick Test. In particular, the Taekwondo Anaerobic Intermittent Kick Test showed good ability to effectively discriminate between taekwondo athletes of different competitive levels.
The Effect of Sports Rules Amendments on Exercise Intensity during Taekwondo-Specific Workouts (2020)
We aimed to compare the change in exercise response to taekwondo-specific circuit workouts before and after competition rule amendments. A total of 240 workouts in 15 elite athletes were analyzed over two years. Physiological and kinematic data were gathered with the wireless Bioharness system along with capillary blood samples for lactate concentration. Progressive exercise tests until exhaustion were periodically performed to obtain reference data. The rule changes resulted in significant increases (mainly medium or large effects) in the physiological (2.9–14.4%) and kinematic (4.8–10.1%) response to taekwondo-specific workouts. The largest increases were for peak breathing rate (12.0%), energy expenditure (6.6%), blood lactate immediately after exercise (10.2%) and at the 30th min of recovery (14.4%), and peak kinematic activity (10.1%). Significant differences between taekwondo-specific workouts and tournament combats persisted after the shift from old to new rules, ranging from 2.4 to 38.5% for physiological and from 2.9 to 15.5% for kinematic variables. The largest workout–combat differences were revealed for post-exercise (15.9%) and recovery (38.5%) blood lactate, peak (−15.8%) and relative (−15.0%) breathing rate, and mechanical (13.5%) and physiological (14.2%) intensity. Our study suggests that the rule amendments significantly modify the exercise response to discipline-specific workouts and that taekwondo-specific training sessions do not fully recreate the tournament demands in terms of physiological and kinematic load.
Tennis
Epidemiology of Injuries in Tennis Players (2017)
Purpose of review To review the recent literature regarding the epidemiology of tennis injuries at all levels of play, and to discuss recent findings in injury surveillance by the Association of Tennis Professionals.
Forearm Muscle Activation, Ulnar Nerve at the Elbow and Forearm Fatigue in Overhand Sports(2020)
This study examined the morphologic changes of the ulnar nerve in different elbow positions by ultrasonography and the effects of fatigue on forearm muscle control during overhand movements. We enrolled 12 tennis players who performed flat serves and 15 baseball pitchers who performed fastball pitching. The motion capture was conducted with 14 reflective markers attached on anatomic landmarks of the participant for tennis serve and baseball pitching data collection. The distance from the nerve to the medial condyle between the tennis players and baseball pitchers showed significant differences (p = 0.006) as the elbow flexed to 90°. The differences are due to the baseball player’s repetitive pitching motion while such motion does not apply to tennis player. Activity of the extensor carpi radialis (ECR) during the cocking phase in the tennis serves showed significant differences (p = 0.022) between the nonfatigued and fatigued states; the maximal value was observed in the fatigued state. The significant increase in the ECR activity in the fatigued state might be responsible for grasp-and-release activities and maintaining the wrist joint stability when performing overhand movements. Forearm fatigue influenced their overhand motion ability in accurate ball control, although it did not decrease the ball speed.
Investigating the Nutritional and Recovery Habits of Tennis Players(2018)
In this study, the nutritional and recovery habits of tennis players pre-, during, and post-match-play were investigated. Seventy tennis players completed a bespoke nutrition and recovery habits questionnaire, with questions related to the following areas: match preparation, intra-match nutritional habits, situation dependent variables, and post-match nutrition and recovery. On match day-1, the consumption of balanced meals consisting of carbohydrate (CHO), fat and protein, with some micronutrient considerations were reported by 51% of players. On match-days, CHOs were prioritised prior to match-play with CHO dominant meals consumed by the majority of players. During matches, all players adopted a nutritional strategy, with water (94%), banana(s) (86%) and sports drinks (50%) commonly used. Carbohydrate rich nutritional aids, including sports drinks (80%) and energy gels (26%) were utilised more readily during long matches (>2 h). The day after match-play, 39% of players reported the consumption of "nothing specific". Multiple post-match recovery strategies were adopted by 80% of players, with foam rolling (77%), ice baths (40%), protein shake intake (37%) and hot baths (26%) most used. Findings indicate highly variable eating and recovery habits in tennis players pre-, during and post-match-play, with scope for improved practices.
Long-term Tennis Participation and Health Outcomes: An Investigation of “Lifetime” Activities (2020)
Lifetime sports, such as tennis, provide opportunities for participation throughout the lifespan and has been linked with lower risk of cardiovascular disease, obesity, and depression. The objective of this study was to consider the influence of chronic tennis participation on various parameters of health. Members of the International Tennis Federation (ITF) completed a survey consisting of questions from International Physical Activity Questionnaire (IPAQ), Behavior Risk Factor Surveillance System (BRFSS), Satisfaction With Life Survey (SWLS), and specific tennis participation questions. Descriptive characteristics were calculated for all variables and a chi-squared analysis was used to compare prevalence of health variables of this sample and recent BRFSS data. Compared to the BRFSS greater proportion of study participants 45yrs and older frequently reported being in good or better health (χ2=7.946, p = 0.005); lower obesity rates (χ2=19.92, p = 0.0001); and a lower prevalence of heart disease than those of similar age who completed BRFSS (χ2= 8.759, p = 0.003). This study highlights the importance of activities that continue throughout the lifespan such as tennis.
Performance Profiles of Professional Female Tennis Players in Grand Slams (2018)
The aim of the study was to (i) analyze the match performance of professional female tennis players in different Grand Slams; (ii) model the relationships between match performance variables and relative quality; and (iii) build typical performance profiles for those players in Grand Slams.
Quantifying Hitting Activity in Tennis With Racket Sensors: New Dawn or False Dawn? (2020)
The non-invasive measurement of movement through sensor technologies is common in elite sport, yet only recently become possible in tennis. This study validated two commercial tennis racquet sensors compared to gold standards in VICON and expert notational analysis. One national-level male tennis player hit 24 shots (9 forehands and 9 backhands, hit with heavy topspin, flat and slice; 6 serves) using a Babolat Play racket with a Zepp sensor. Measures of shot type, impact location and racket speed were compared against those captured by a 500-Hz 12 camera VICON system. Cohen’s kappa (κ) and a weighted kappa (κ w) assessed the accuracy of stroke classification and impact location, respectively, and intraclass correlation coefficients (ICC) validated sensor-derived racket speed. Both sensors recorded the same total stroke volume as VICON, while Zepp racket speed displayed near perfect agreement with VICON (ICC = 0.983; p < 0.001). They exhibited moderate agreement with true stroke classification (Babolat: κ = 0.730; Zepp: κ = 0.612) and minimal agreement with true impact location (Babolat: κ w = 0.412; Zepp: κ w = 0.217). During match play, both sensors achieved near perfect accuracy for stroke volume but experienced difficulty discriminating the different stroke types. In sum, the Babolat Play and Zepp determined stroke volume and intensity accurately but were less effective in identifying specific strokes and impact locations.
Simulation of Tennis Serve Behavior Based on Video Image Processing and Wireless Sensor Technology (2020)
Video-based human motion analysis is an important research direction in the field of computer vision. It detects moving objects from video sequences, extracts key parts of the human body, and obtains useful information for human movements. In this paper, the joints of the teeing arm are first color-coded. The tennis teeing video is collected by a high-speed camera. The coordinates of the tacking points in each frame are used instead of the knuckles to study the trajectory of the teeing arm. In the process of video processing, after constructing a dictionary for a series of noise maps, the sparse representation idea was used to reconstruct an interference-free service diagram, and a mixture of Gaussian background modeling was used to extract the foreground of the motion. After obtaining the motion foreground, the marker points are extracted through the color features, and binarization operations are performed on the marker points. Next, the outline of the marker points is searched, the outline is surrounded by the minimum circle, and the returned circle center coordinates are used as the joint point coordinates. Taking the trajectory of the shoulder marking point as a research object, a tennis serving model based on an improved support vector machine was established.
Withdrawals and Retirements in Professional Tennis Players (2017)
Injuries and illnesses for professional tennis athletes disrupt training, competition, and progression in the sport and represent a major reason for athlete withdrawal or retirement from a tournament. Few descriptive epidemiological studies have focused on these trends in elite tennis athletes.
Triathlon
Acute Effects of Triathlon Race on Oxidative Stress Biomarkers (2020)
The response to strenuous exercise was investigated by reactive oxygen species (ROS) production, oxidative damage, thiol redox status, and inflammation assessments in 32 enrolled triathlon athletes (41.9 ± 7.9 yrs) during Ironman® (IR), or half Ironman® (HIR) competition. In biological samples, inflammatory cytokines, aminothiols (glutathione (GSH), homocysteine (Hcy), cysteine (Cys), and cysteinylglycine (CysGly)), creatinine and neopterin, oxidative stress (OxS) biomarkers (protein carbonyl (PC), thiobarbituric acid-reactive substances (TBARS)), and ROS were assessed. Thirteen HIR and fourteen IR athletes finished the race. Postrace, ROS (HIR +20%; IR +28%; p < 0.0001), TBARS (HIR +57%; IR +101%), PC (HIR +101%; IR +130%) and urinary neopterin (HIR +19%, IR +27%) significantly (range p < 0.05-0.0001) increased. Moreover, HIR showed an increase in total Cys +28%, while IR showed total aminothiols, Cys, Hcy, CysGly, and GSH increase by +48, +30, +58, and +158%, respectively (range p < 0.05-0.0001). ROS production was significantly correlated with TBARS and PC (R2 = 0.38 and R2 = 0.40; p < 0.0001) and aminothiols levels (range R2 = 0.17-0.47; range p < 0.01-0.0001). In particular, ROS was directly correlated with the athletes' age (R2 = 0.19; p < 0.05), with ultraendurance years of training (R2 = 0.18; p < 0.05) and the days/week training activity (R2 = 0.16; p < 0.05). Finally, the days/week training activity (hours/in the last 2 weeks) was found inversely correlated with the IL-6 postrace (R2 = ‐0.21; p < 0.01). A strenuous performance, the Ironman® distance triathlon competition, alters the oxidant/antioxidant balance through a great OxS response that is directly correlated to the inflammatory parameters; furthermore, the obtained data suggest that an appropriate training time has to be selected in order to achieve the lowest ROS production and IL-6 concentration at the same time.
Biochemical Markers After the Norseman Extreme Triathlon (20200)
Prolonged exercise is known to cause changes in common biomarkers. Occasionally, competition athletes need medical assistance and hospitalisation during prolonged exercise events. To aid clinicians treating patients and medical teams in such events we have studied common biomarkers after at The Norseman Xtreme Triathlon (Norseman), an Ironman distance triathlon with an accumulated climb of 5200 m, and an Olympic triathlon for comparison. Blood samples were collected before, immediately after, and the day following the Norseman Xtreme Triatlon (n = 98) and Oslo Olympic Triathlon (n = 15). Increased levels of clinical significance were seen at the finish line of the Norseman in white blood cells count (WBC) (14.2 [13.5-14.9] 109/L, p < 0.001), creatinine kinase (CK) (2450 [1620-3950] U/L, p < 0.001) and NT-proBNP (576 [331-856] ng/L, p < 0.001). The following day there were clinically significant changes in CRP (39 [27-56] mg/L, p < 0.001) and Aspartate Aminotransferase (AST) (142 [99-191] U/L, p < 0.001). In comparison, after the Olympic triathlon distance, there were statistically significant, but less clinically important, changes in WBC (7.8 [6.7-9.6] 109/L, p < 0.001), CK (303 [182-393] U/L, p < 0.001) and NT-proBNP (77 [49-88] ng/L, p < 0.01) immediately after the race, and in CRP (2 [1-3] mg/L, p < 0.001) and AST (31 [26-41] U/L, p < 0.01) the following day. Subclinical changes were also observed in Hemoglobin, Thrombocytes, K+, Ca2+, Mg2+, Creatinine, Alanine Aminotransferase and Thyroxine after the Norseman. In conclusion, there were significant changes in biomarkers used in a clinical setting after the Norseman. Of largest clinical importance were clinically significant increased WBC, CRP, AST, CK and NT-proBNP after the Norseman. This is important to be aware of when athletes engaging in prolonged exercise events receive medical assistance or are hospitalised.
Futureproofing Triathlon: Expert Suggestions to Improve Health and Performance in Triathletes (2020)
Given the multi-modal nature of triathlon (swimming, cycling, running), training for a triathlon event has numerous potential health benefits including physical fitness. However, triathletes also have a high prevalence of health issues including overuse injury, illness, fatigue, and burnout. To address the ongoing prevalence of health issues, roundtable discussions were organized at the International Triathlon Union Science of Triathlon 2017 conference to develop strategic objectives deemed necessary to “futureproof triathlon”. Futureproofing as a concept serves to design new approaches and ways of thinking to reduce consequences in the future. In this case, the futureproof process aimed to develop key recommendations for triathlon.
Self-Selected Pacing During a World Record Attempt in 40 Ironman-Distance Triathlons in 40 Days (2020)
The present case study analyzed performance, pacing, and potential predictors in a self-paced world record attempt of a professional triathlete to finish 40 Ironman-distance triathlons within 40 days. Split times (i.e., swimming, cycling, running) and overall times, body weight, daily highest temperature, wind speed, energy expenditure, mean heart rate, and sleeping time were recorded. Non-linear regressions were applied to investigate changes in split and overall times across days. Multivariate regression analyses were performed to test which variables showed the greatest influence on the dependent variables cycling, running and overall time. The athlete completed the 40×Ironman distances in a total time of 444:22 h:min. He spent 50:26 h:min in swimming, 245:37 h:min in cycling, 137:17 h:min in running and 11:02 h:min in transition times. Swimming and cycling times became slower across days, whereas running times got faster until the 20th day and, thereafter, became slower until the 40th day. Overall times got slower until the 15th day, became faster to 31st, and started then to get slower until the end. Wind speed, previous day’s race time and average heart race during cycling were significant independent variables influencing cycling time. Body weight and average heart rate during running were significant independent variables influencing running performance. Cycling performance, running performance, and body weight were significant independent variables influencing overall time. In summary, running time was influenced by body weight, cycling by wind speed, and overall time by both running and cycling performances.
Sex Difference in Triathlon Performance (2019)
This brief review investigates how sex influences triathlon performance. Performance time for both Olympic distance and Ironman distance triathlons, and physiological considerations are discussed for both elite and non-elite male and female triathletes. The relative participation of female athletes in triathlon has increased over the last three decades, and currently represents 25–40% of the total field. Overall, the sex difference in both Olympic and Ironman distance triathlon performance has narrowed across the years. Sex difference differed with exercise mode and exercise duration. For non-elite Ironman triathletes, the sex difference in swimming time (≈12%) is lower than that which was evidenced for cycling (≈15%) and running (≈18%). For elite triathletes, sex difference in running performance is greater for Olympic triathlon (≈14%) than it is for Ironman distance triathlon (≈7%). Elite Ironman female triathletes have reduced the gap to their male counterparts to less than 10% for the marathon. The sex difference in triathlon performance is likely to be due to physiological (e.g., VO2max) and morphological (e.g., % body fat) factors but hormonal, psychological and societal (e.g., lower participation rate) differences should also be considered. Future studies should address the limited evidence relating sex difference in physiological characteristics such as lactate threshold, exercise economy or peak fat oxidation.
The Age-Related Performance Decline in Ironman 70.3 (2020)
Although the age-related decline in sport events has been well studied, little is known on such a decline in recreational triathletes for the Half Ironman distance. Indeed, the few existing studies concentrated on specific aspects such as top events, elite groups, some consecutive years, single locations, or age categories instead of analyzing all the data available. Therefore, the aim of the present study was to examine recreational triathletes’ performance in three split disciplines (swimming, cycling, and running) as well as in overall race time by analyzing all data of Half Ironman finishers found on ironman.com (i.e., 690 races; years 2004 through 2018; 206,524 women (24.6%) and 633,576 men (75.4%), in total 840,100 athletes). The age-dependent decline in Half Ironman started earliest in swimming (from the very first age group on) with a smallest age group delta between 35–49 years in men and 40–54 years in women. The performance decline started at 26 and 28 years in men and women for running; at 34 years for men and 35 years for women in cycling; and at 32 years for men and 31 years for women with regard to overall race time. The results may be used by coaches and recreational athletes alike to plan a triathlon career.
Training and Competition Readiness in Triathlon (2019)
Triathlon is characterized by the multidisciplinary nature of the sport where swimming, cycling, and running are completed sequentially in different events, such as the sprint, Olympic, long-distance, and Ironman formats. The large number of training sessions and overall volume undertaken by triathletes to improve fitness and performance can also increase the risk of injury, illness, or excessive fatigue. Short- and medium-term individualized training plans, periodization strategies, and work/rest balance are necessary to minimize interruptions to training due to injury, illness, or maladaptation. Even in the absence of health and wellbeing concerns, it is unclear whether cellular signals triggered by multiple training stimuli that drive training adaptations each day interfere with each other. Distribution of training intensity within and between different sessions is an important aspect of training. Both internal (perceived stress) and external loads (objective metrics) should be considered when monitoring training load. Incorporating strength training to complement the large body of endurance work in triathlon can help avoid overuse injuries. We explore emerging trends and strategies from the latest literature and evidence-based knowledge for improving training readiness and performance during competition in triathlon.
Volleyball
Female Volleyball Players are More Prone to Cortisol Anticipatory Stress Response than Sedentary Women (2019)
Background and Objectives: Top-level sports performance places heavy physical and psychological demands on elite-level athletes, which can be a source of increased levels of stress. Therefore, high-level volleyball players may present altered cardiovascular and endocrinological stress response during stressful events. Although many previous studies have examined the response to stress on athletes, most of them regarded only males, while the impact of the female menstrual cycle has rarely been taken into account. We aimed to study psychophysiological response to anticipatory stressor through analysis of heart rate, self-reported anxiety level, and salivary cortisol in healthy young female athletes by minimalizing the effect of confounders. Materials and Methods: A total of 55 females (25 members of the best league for female volleyball players in Poland and 30 sedentary-lifestyle control subjects) in the follicular phase of their menstrual cycle were exposed to mental arithmetic tasks as an experimental imitation of the stressor. Volleyball players were significantly taller than sedentary individuals (177.1 ± 3.4 cm vs. 173.3 ± 3.4 cm, respectively, p = 0.034), but did not differ in weight (73.6 ± 5.2 kg vs. 70 ± 4.23 kg, respectively, p = 0.081), body mass index (BMI) (23.5 ± 1.13 vs. 24.1 ± 1.45, respectively, p = 0.060), and age (22 ± 1.11 vs. 23 ± 1.14 years, respectively, p = 0.2). Their stress responses were assessed through self-reported anxiety levels and physiological measurements of salivary cortisol concentrations and heart rate (HR). Results: For HR, significant effects of time (F(2,120) = 21.34, p < 0.001, η2 = 0.26) were found, but not for training status (F(1,60) = 2.69, p = 0.106, η2 = 0.04). For cortisol levels, the analysis showed the main effects of time (F(3,180) = 11.73, p < 0.001, η2 = 0.16) and training status (F(1,60) = 4.69, p = 0.034, η2 = 0.07) and a significant interaction between training status and time (F(3,180) = 3.07, p = 0.029, η2 = 0.05). Post-hoc analyses showed higher cortisol concentrations among volleyball players following the math task (all p < 0.001), as well as higher cortisol concentrations in S2, S3, and S4 compared to S1 in volleyball players (all p < 0.001). We observed also a significant increase in state anxiety in both groups (all p < 0.001), but no differences in state anxiety levels between groups. Conclusion: Female volleyball players may not differ in subjective graduation of stressors; however, exposure to training-based stressors seems to promote cortisol response to the anticipated stressor.
Investigating Cumulative Effects of Pre-performance Routine Interventions in Beach Volleyball Serving(2020)
Pre-performance routines (PPRs) can be used in certain sports to minimize the effects of choking under pressure. This study aimed to investigate the cumulative effectiveness of PPR interventions on the accuracy of beach volleyball serves. Fifty-four beach volleyball players were randomly assigned to one of three PPR intervention groups or a control group. Participants performed 10 serves at a target on the opposite side of the beach volleyball court (pretest), were educated on a PPR intervention, and then completed 10 serves at the target under pressure that was induced through videotaping and ego-relevant instructions (posttest). The results indicated no difference in post-test serving accuracy among the intervention groups and the wait-list control group and no difference in effectiveness between cumulative and isolated PPR use. A possible explanation may be the inefficiency of the pressure manipulation. However, the null results related to isolated and cumulative PPR use under general (i.e., no pressure) conditions are still an important research finding. Future research should investigate the effectiveness of cumulative and other PPRs in other sports in general and under pressur.
Performance Streaks in Elite Beach Volleyball - Does Failure in One Sideout Affect Attacking in the Next? (2019)
This study explores the influence of sideout failure on performance in the next sideout in beach volleyball. The sample comprises 965 elite matches in the FIVB World Series 2012-2016 and in the Olympic Games 2012/2016 including 28,974 sideout sequences (12,755 for men and 16,219 for women). A sideout sequence consists of two sideouts by the same player during the same set in a timeframe of four rallies. The first sideout in this sequence is referred to as the previous sideout and the second sideout as the next sideout. After misses, χ2-tests indicate a significantly higher technique alternation rate (from spike to shot or vice versa) in the next sideouts for both men (+32.7%) and women (+40.4%) than the next sideouts after hits. After shot misses, the share of shots in the next sideouts was -12.9% lower for men and -8.3% lower for women than the next sideouts after shot hits. After spike misses, the share of shots in the next sideouts by female players was +5.5% significantly higher, and shot hit rate was -6.5% lower than the next sideouts after spike hits. These findings support the belief that tactical decisions and performance in top-level beach volleyball are influenced by failure in the previous sideouts. They might support coaches and players when analyzing matches and developing game strategies.
The Prevention of Musculoskeletal Injuries in Volleyball: The Systematic Development of an Intervention and its Feasibility (2017)
Background: A scientific research project has started in the Netherlands with the aim of developing and implementing an evidence-based intervention to prevent the occurrence of musculoskeletal injuries among young and adult recreational volleyball players. This article describes (i) the systematic development of the intervention; and (ii) the assessment of its feasibility in terms of relevancy, suitability and usability.
Volleyball Overhead Swing Volume and Injury Frequency Over the Course of a Season(2019)
Overuse injuries are common in volleyball; however, few studies exist that quantify the workload of a volleyball athlete in a season. The relationship between workload and shoulder injury has not been extensively studied in women's collegiate volleyball athletes.
Which are the Nutritional Supplements Used by Beach-Volleyball Athletes? A Cross-Sectional Study at the Italian National Championship (2020)
Beach volleyball is an intermittent team sport played under high temperature and humidity. Given that some nutritional supplements can enhance sports performance, this study aimed to evaluate the quantity and the heterogeneity of the nutritional supplementation practices of amateur (n = 69) and professional (n = 19) beach volley athletes competing in the Italian National Championship; an online form was used to collect data about the supplementation habits. The latent class analysis was used to find sub-groups characterised by different habits regarding supplements consumption. The most frequently used supplements (more than once a week) are vitamins B and C (39.2% of athletes), protein (46.8%), and caffeine (36.9%). The latent class analysis revealed three different sub-groups of athletes: the first class (56.7%) included athletes who were used to take very few supplements, the second class (17.0%) was characterised by higher consumption of supplements and the third class (26.2%) was in the middle between the others two. Groups were characterised not only by the quantity but also by the category of supplements used. Our results highlighted a high heterogeneity in supplementation habits. A pragmatic approach to supplements and sports foods is needed in the face of the evidence that some products can usefully contribute to enhancing performance.
