Muscle damage produced during a simulated badminton match in competitive male players

Testing in Intermittent Sports-Importance for Training and Performance Optimization in Adult Athletes

ABSTRACT

Performance in intermittent sports relies on the interplay between multiple physiological systems determining the capacity to perform short explosive efforts as well as repeated intense actions with limited recovery over the course of an entire game. Testing should reflect these demands to allow for sport- and position-specific capacity analyses that eventually may translate into optimized training and improved performance. This may include individual load management and optimized training prescription, intensity targeting for specific positions or individual athletes, as well as benchmarking for monitoring of training progression and enhanced engagement of athletes. This review provides an overview of available tests in different exercise domains identified as relevant (from assessment of single explosive actions to intermittent endurance capacity), forming the basis for recommendations on how to compose a comprehensive yet feasible test battery that may be integrated into the seasonal competition and training plan. The test procedures should cover the performance spectrum of relevance for the individual athlete-also in team sports to account for positional differences. We emphasize the benefits of sport-specific tests, highlight parameters of importance for test standardization, and discuss how the applied test battery may be supplemented with secondary tests directed toward specific energy systems to allow for more in-depth analyses when required (e.g., in terms of an underperforming athlete). The synergy between testing and tracking of match performance (utilizing time-motion or global positioning systems) is highlighted, and although tracking cannot substitute for testing, combining the tools may provide a comprehensive overview of the physiological demands and performance during competition contextualized to the athletes' maximal exercise capacity.

Recovery from sport-induced muscle damage in relation to match-intervals in major events

Muscle damage could affect the next match performance in sports when the time to recover from a previous match is shorter. We examined the interval between matches in nine team sports (e.g., soccer, rugby, field hockey, basketball, volleyball, baseball) and two racket sports (badminton, tennis) in World Cups held in 2022-2023, 2020 Tokyo Olympic Games and Gland Slam in 2023. We then performed narrative review using three electronic databases (PubMed, Scopus, Google Scholar) to get information about muscle damage and recovery in the 11 sports, and discussed whether the intervals in the events would be enough for athletes. We found that the match intervals varied among sports and events ranging from 0 to 17 days. The interval was the shortest for softball (0-2 days) and the longest (5-17 days) for rugby. Regarding muscle damage, changes in muscle function and/or performance measures after a match were not reported for cricket, volleyball and softball, but some information was available for other sports, although the studies did not necessarily use athletes who participated in the major events. It was found that recovery was longer for soccer and rugby than other sports. Importantly, the match-intervals in the events did not appear to accommodate the recovery time required from the previous match in many sports. This could increase a risk of injury and affect players' conditions and health. Changing the match-intervals may be difficult, since it affects the budget of sporting events, but an adequate interval between matches should be considered for each sport from the player's and coach's point of view.

Influence of Successive Wheelchair Tennis Matches on Handgrip Strength in High-Level Male Players

The purpose of this study was to examine the effects on upper strength in high-level male players playing four successive wheelchair tennis (WT) matches. Eight international WT players took part in a competition, playing one match per day over four consecutive tournament days. Before and after the match, the maximal isometric handgrip strength was measured on the dominant and non-dominant hand. Additionally, each player was equipped with one radiofrequency and IMU device on their wheelchair to control his activity profile (distance). The results showed significant differences between successive matches, with decreasing dominant handgrip strength (p = 0.02, η² = 0.043), and there was a significant interaction between successive matches and the accumulated distance (p = 0.013, η² = 0.049). The pre- and post-match strength values of the dominant hand decreased throughout the matches over a number of days, and post hoc analysis showed differences between the first and fourth matches only in pre-match strength (49.06 ± 6.96 vs. 45.94 ± 7.1; p = 0.045; ES: 1.04) but not in the non-dominant hand. Successive matches caused a decrease in the strength values of the WT players, mainly in the dominant hand. These results should be taken into account in the recovery and prevention of injuries in competitions with successive matches.

Genotype Distribution of the ACTN3 p.R577X Polymorphism in Elite Badminton Players: A Preliminary Study

α-Actinin-3 is a protein with a structural role at the sarcomeric Z-line in skeletal muscle. As it is only present in fast-type muscle fibers, α-actinin-3 is considered a key mechanical component to produce high-intensity muscle contractions and to withstand external tension applied to the skeletal muscle. α-Actinin-3 is encoded by the gene ACTN3, which has a single-nucleotide polymorphism (p.R577X; rs1815739) that affects the expression of α-actinin-3 due to the presence of a stop codon. Individuals homozygous for the 577R allele (i.e., RR genotype) and RX heterozygotes express functional α-actinin-3, while those homozygous for the 577X (i.e., XX genotype) express a non-functional protein. There is ample evidence to support the associations between the ACTN3 genotype and athletic performance, with higher frequencies of the 577R allele in elite and professional sprint and power athletes than in control populations. This suggests a beneficial influence of possessing functional α-actinin-3 to become an elite athlete in power-based disciplines. However, no previous investigation has determined the frequency of the ACTN3 genotypes in elite badminton players, despite this sport being characterized by high-intensity actions of intermittent nature such as changes of direction, accelerations, jumps and smashes. The purpose of this study was to analyze ACTN3 R577X genotype frequencies in professional badminton players to establish whether this polymorphism is associated with elite athlete status. A total of 53 European Caucasian professional badminton players competing in the 2018 European Badminton Championships volunteered to participate in the study. Thirty-one were men (26.2 ± 4.4 years) and twenty-two were women (23.4 ± 4.5 years). Chi-squared tests were used to analyze the differences in the distribution of ACTN3 genotypes (RR, RX and XX) between categories and sexes. The ACTN3 RR genotype was the most frequent in the sample of professional badminton players (RR = 49.1%, RX = 22.6% and XX = 28.3%). None of the badminton players ranked in the world's top ten possessed the XX genotype (RX = 60%, RR = 40%). The distribution of the ACTN3 genotypes was similar between male and female professional badminton players (men: RR = 45.2%, RX = 25.8% and XX = 29.0%; women: RR = 54.5%, RX = 18.2% and XX = 27.3%; χ² = 0.58; p = 0.750). The distribution of the ACTN3 genotypes in badminton players was different from the 1000 genome database for the European population (χ² = 15.5; p < 0.001), with an overrepresentation of the RR genotype (p < 0.05) and an underrepresentation of the RX genotype (p < 0.01). In conclusion, the expression of functional α-actinin-3, associated with RR and RX genotypes in the ACTN3 gene may confer an advantage for reaching the status of elite athlete in badminton, and especially the world's top-ten ranking. Large-scale studies with different ethnic backgrounds are needed to confirm the association of the R allele of ACTN3 with badminton performance.

Analysis of Winning Experience and Technical Training Effect of Badminton Match Based on BP Neural Network

The success or failure of badminton competition often depends on the training level of technical, physical, tactical, and psychological quality, as well as the competitive ability to comprehensively use these factors in the competition. Aiming at the improvement of the BP neural network algorithm, the improved BP neural network algorithm is used to analyze the multidimensional attributes of the collected data, and the simulation experiment is carried out to find out our competitive advantages and disadvantages. This paper presents a statistical study on the change of service area, the application of service receiving technology, and the treatment of the third stroke technology in the badminton competition. The innovative contribution of this paper is to explore the differences of double service decision-making of badminton at different levels and form a theoretical mechanism analysis system. The research shows that the relationship between active and passive attack and hitting quality has been dealt with in the game. In training, mastering the basic technical movements of badminton is conducive to improving the technical level of badminton.

Effectiveness of On-Court Resistive Warm-Ups on Change of Direction Speed and Smash Velocity during a Simulated Badminton Match Play in Well-Trained Players

In badminton, power production can be enhanced through the fundamental practice of a dynamic warm-up with resistance conditioning activity to induce a post-activation performance enhancement (PAPE) effect. The use of heavy resistance exercise in the form of heavy weights to induce PAPE during competition is not logistically practical in the badminton arena. Thus, there is a need to investigate the use of easily available alternative preconditioning stimuli to induce a similar potentiating effect in badminton-specific performance. This study adopted a repeated-measures design of three warm-up conditions: control (CON), weighted wearable resistance (WWR), and resistance band variable resistance (BVR). Fourteen badminton players from the national training squad (11 males, 3 females, age 18 ± 1 y) completed the experimental sessions in random order. Change of direction speed (CODS) and smash velocity (SV) tests were performed at five timepoints-baseline test after the warm-up and at the end of each of the four exercise blocks of a simulated match play protocol. CODS was significantly faster under the two resistance warm-up conditions (WWR and BVR) compared to the CON condition at baseline (-0.2 s ± 0.39 and -0.2 s ± 0.46, p = 0.001 and 0.03, g = 0.47 and 0.40, respectively), but there were no differences at the other timepoints (all p > 0.05). SV was significantly faster for all the four exercise blocks than at baseline under all three warm-up conditions (p = 0.02), but there were no differences in SV between the three warm-up conditions across all the five measured timepoints (p = 0.15). In conclusion, implementing resistance (~10% body weight) in sport-specific plyometric exercises using WWR or BVR during warm-up routines may induce PAPE effects on the change of direction speed but not smash velocity, in well-trained badminton players, as compared with the same warm-up exercises using bodyweight (i.e., CON condition). The positive effects of CODS were, however, observed only at the start of the match and possibly lasted for up to between 5 and 10 min of match play.

AIR-BT, a new badminton-specific incremental easy-to-use test

Background

Badminton is a highly demanding sport characterized by intermittent efforts with energy being provided by both the aerobic and anaerobic systems. To date, no incremental badminton field test has been developed that can be easily used by badminton coaches that requires accessible material for anyone.

Objectives

The purpose of this study was to develop a practical and reliable easy-to use intermittent endurance badminton test for estimating maximal oxygen uptake (VO_2max).

Methods

Thirty six Spanish badminton players (age: 24.1±10.3 years) performed, on different days of the same week, four incremental protocols to exhaustion in randomized order: a treadmill incremental test, a Yo-Yo intermittent recovery level 1 test (Yo-Yo IR1) and twice the Abian intermittent recovery badminton test (AIR-BT). Oxygen uptake was determined with a breath-by-breath gas analyzer during the incremental treadmill test, and performance in the Yo-yo IR1 and AIR-BT was recorded.

Results

Significant correlations (p<0.001) for Pearson’s product moment coefficient were found between the performance in the AIR-BT and the two non-specific incremental tests (VO_2max in the Treadmill Test: r = 0.87, distance in the Yo-Yo IR1: r = 0.86). The regression equation to calculate the VO_2max from the AIR-BT time [VO_2max = 0.023*(AIR-BT time in seconds)+31.334] showed an adjusted R² of 0.76 and a SEE of 3.34 ml·kg^-1·min^-1. There was no significant difference between VO_2max obtained by the incremental treadmill test and VO_2max calculated using the regression equation (p = 0.644). A paired t-test reported no significant differences between day 1 and day 2 in the AIR-BT time (p = 0.753), the Pearson correlation coefficient between both days was: r = 0.88 (p<0.001) and the intraclass correlation coefficient was 0.875.

Conclusions

The AIR-BT is a valid and reliable on-court test for assessing VO_2max in badminton players and may be utilized by coaches and physical trainers for cross-sectional comparison of players and for evaluation of longitudinal changes.

Gender Differences in Neuromuscular, Haematological and Urinary Responses during Padel Matches

Research on the acute physiological response to a padel match is limited. The present study aimed to: (a) evaluate neuromuscular, urinary, and hematological responses after simulated padel competition (SC) and (b) analyze possible gender differences. In this study, 28 high-level padel players participated (men = 13, age = 26.83 ± 6.57 years; women = 15, age = 30.07 ± 4.36 years). The following parameters were analyzed before and after SC: neuromuscular (hand grip strength, squat jump (SJ), countermovement jump (CMJ), and Abalakov jump (ABK)), hematological (red blood cells, hemoglobin, and hematocrit), and urinary (pH, specific gravity, microalbuminuria, and red blood cells). Significant gender differences were found in neuromuscular and hematological responses, with men obtaining higher values (p < 0.05). For the SC influence, changes were noted in ABK and microalbuminuria (p < 0.05). The percentages of change in hand grip strength, SJ (height and watts), CMJ (height), and ABK (height) were higher for men than women (p < 0.05). SC negatively influenced the neuromuscular parameters to a greater extent in women. Our results could be related to gender differences in game actions, the temporal structure, and anthropometric and physiological characteristics. Game dynamics and a different organic response between male and female padel playing were confirmed.

Periodontal Health, Nutrition and Anthropometry in Professional Footballers: A Preliminary Study

Poor oral health in elite sport is a pressing issue, however little is known about the periodontal status of professional footballers. The aim of this study was to examine the prevalence of periodontitis in a group of professional footballers and its association with nutritional parameters and self-report non-traumatic injuries. Additionally, we assessed its association with anthropometric, dietary inflammatory load and self-reported muscular and/or articular injuries. Twenty-two professional footballers were evaluated at the beginning of the 2020–2021 season via full-mouth periodontal inspection, anthropometric measurements and the application of the dietary inflammatory index through a food intake measurement of 24 h dietary recall on two different days. Self-reporting non-traumatic muscular and articular injuries for the past 6 months were recorded from each athlete. Then we compared clinical measurements according to the periodontal status and we correlated age, periodontal and nutritional parameters. Overall, the prevalence of periodontitis was 40.9% and peri-implantitis was also observed. No significant differences were found regarding age or nutritional parameters according to the periodontal status. More non-traumatic muscular events in the past 6 months were found in the periodontitis group (55.6% vs. 38.4%), although the difference was non-significant. Both clinical attachment loss, periodontal pocket depth and the periodontal epithelial surface area revealed a significant moderate correlation with the percentage of fat mass, muscle mass, muscle mass index and total adipose folds. This group of professional footballers showed an alarming prevalence of periodontitis. Further studies shall examine whether periodontitis and periodontal treatment impact the performance of this group of athletes.

Acute Effects of 2 Consecutive Simulated Badminton Matches on the Shoulder Range of Motion and Isometric Strength of Elite Youth Players

PURPOSE

To analyze the influence of playing 2 consecutive prolonged badminton matches on the shoulder strength and range of motion (ROM) of young players.

METHODS

Sixteen elite junior badminton players (12 males and 4 females; mean (SD): age 16.2 [0.8] years, body mass 63.5 [6.6] kg, height 173.2 [6.3] cm) participated in a cross-sectional study. Shoulder internal (IR)/external rotation (ER) ROM and IR/ER strength measures were conducted before and after 2 consecutive prolonged (ie, 35 min) matches and 12 hours after the second match.

RESULTS

After consecutive matches, IR strength of the dominant side and ER strength of the dominant and nondominant sides (effect size [ES] = 0.20-0.57) were reduced. Shoulder total ROM of the dominant side was decreased (ES = 0.80), while on the nondominant side, IR (ES = 0.66) was also decreased. After 12 hours, results showed decreased values in the IR/ER strength of the dominant side (ES = 0.36-1.00), as well as ER of both dominant and nondominant sides (ES = 0.30-0.59). IR ROM of the nondominant side (ES = 0.69) was also decreased.

CONCLUSION

Present results showed that 2 consecutive matches on the same day with brief rest periods led to significant impairments in shoulder strength and ROM levels. These data can potentially elucidate the need for shoulder-specific training and recovery strategies prior to or during competitions.

Muscle Injury in Bodybuilding Based on Mesoporous Multifunctional Nanomaterials for Sports Rehabilitation Training

As an important means of treating diseases, chemical-based drugs have always guaranteed people’s health and longevity. However, due to the nature of some drugs, their use in the medical field is limited. This study mainly discusses the treatment of muscle damage based on sports rehabilitation training mesoporous multifunctional nanomaterials in bodybuilding. The biological characteristics of the targeted control of mesoporous multifunctional nanomaterials for target drugs were studied by analyzing the regeneration of skeletal muscles of mice after gastrocnemius strain under computer control. The electrostatic interactions modified by the consensus binding between AS1411 and Dimer-PPTcDA on the surface of mesoporous silicon are used to block the pores, and the release of objective molecules depends on the concentration of the drug in the tendon cells and the time of action. In this system, AS1411 has both the characteristics of the target substance and the active site of the targeted stimulus response in the cell. After FAM is labeled AS1411, the fluorescence of FAM can be used to monitor the release of the drug in real time, so as to directly release the drug to the lesion, maintain local effectiveness, and greatly improve the biological activity of the drug. In addition, in the safety analysis of mesoporous multifunctional nanomaterials on cells, if the concentration of nanoparticles is 90 μg/mL, the cell survival rate is almost 100%. The results show that the mesoporous multifunctional nanomaterials have low cytotoxicity and cell activity is not affected. The smaller the particle size of mesoporous silicon, the easier it is to invade the focus cells. In addition, confocal microscopy imaging has also effectively demonstrated the targeting effect of mesoporous multifunctional nanomaterials on cells.

Effect of a Padel Match on Biochemical and Haematological Parameters in Professional Players with Regard to Gender-Related Differences

Haematological and biochemical parameters have not yet been analysed in professional padel players. The aim of this study was to determine the basal values of these parameters and to observe the effect of a simulated competition on them, including gender-related differences. A total of 14 male professional players (age: 28.2 ± 7.9 years), and 16 female professional players (age: 29.7 ± 3.7 years) participated in this study. Players were allowed to hydrate ad libitum during the matches. Haematological and biochemical values were obtained before and after a simulated competitive padel match. The men’s group showed higher baseline values in red blood cells, haematocrit, haemoglobin, urea, creatinine, uric acid, albumin, glutamic oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), lactate dehydrogenase (LDH) and creatine kinase (CK) (p < 0.01) than the women’s group. Attending to match effect, significant differences were obtained in urea, creatinine, CK and glucose (p < 0.05). Finally, the group x match interaction revealed significant differences in serum concentrations of sodium and chloride (p < 0.05). In conclusion, high-level padel matches provoke several changes in biochemical parameters related to muscle damage and protein catabolism. Recovery and fluid intake strategies could be added regarding gender. The results obtained could be due to the differences in the intensity and volume of the simulated competition.

The influence of a badminton competition with two matches in a day on muscle damage and physical performance in elite junior badminton players

To investigate the effects of a badminton competition with 2 matches in a day on hip strength and range of motion (ROM) and exercise-induced muscle damage in elite junior badminton players. Twenty players (age: 17±0.8 years; body mass: 62.9±6.5 kg, height: 173.8±8.9 cm) participated in this study. Passive hip internal (IR) and external rotation (ER), abduction (ABD) and adduction (ADD) hip ROM, isometric hip ADD and ABD muscle strength, countermovement vertical jump (CMJ) height and blood creatine kinase concentration (CK) were measured before and after a badminton competition during an international tournament. Blood samples were collected 24 h after the end of the last match. Compared to baseline values, hip IR and ER ROM were significantly decreased at post-competition in the dominant (IR=-9.0%; p=0.007 and ER=-15.2%; p=0.002) and non-dominant limbs (IR=-9.08%; p=0.004 and ER=-19.4%; p<0.001). In contrast, hip ADD (13.5%; p<0.001) and ABD (14.6%; p<0.001) strength increased significantly after the competition in the dominant limb and ABD strength increased significantly in the non-dominant limb (9.2%; p=0.001). From baseline values, CK increased after the competition (430.1%) and values remained elevated over baseline values 24 h later (160.4%). Although hip muscle strength increased, a badminton competition with two consecutive matches reduced hip ROM and increased blood CK concentration. This study suggests the necessity of investigating recovery strategies after a badminton competition to return hip ROM to basal values before the next day of the competition.

Badminton players show a lower coactivation and higher beta band intermuscular interactions of ankle antagonist muscles during isokinetic exercise

Previous studies have suggested that skilled athletes may show a specific muscle activation pattern with a lower antagonist coactivation level. Based on the point, we hypothesize that the coupling of antagonistic muscles may be different between badminton players and non-skilled individuals during exercises. The current work was designed to verify the hypothesis. Ten male college students and eight male badminton players performed three maximal voluntary isometric contractions (MVC) and a set of three maximal concentric ankle dorsiflexion and plantar flexions at an angular velocity of 30°, 60°, 120°, and 180°/s. Surface electromyography (EMG) was recorded from the tibialis anterior (TA) and lateral gastrocnemius (LG) muscles during the test. Normalized average EMG amplitude and phase synchronization index (PSI) between surface EMG of TA and LG were calculated. Antagonist muscle coactivation was significantly lower (from 22.1% ± 9.4 and 10.7% ± 3.7 at 30°/s to 22.4% ± 9.7 and 10.6% ± 2.5 at 180°/s for non-players and badminton players group, respectively), and PSI in beta frequency band was significantly higher (from 0.42 ± 0.06 and 0.47 ± 0.15 at 30°/s to 0.35 ± 0.12 and 0.49 ± 0.14 at 180°/s) in the badminton player group compared with the non-player group during isokinetic ankle dorsiflexion contraction. No significant difference was found in antagonist muscle coactivation and PSI between two group subjects during ankle plantar flexion. The decrease of antagonist coactivation may indicate an optimal motor control style to increase the contraction efficiency, while the increase coupling of antagonistic muscles may help to ensure joint stability to compensate for the decrease of antagonist coactivation. Graphical abstract Significant difference of observed indexes between non-players and badminton players.

Differential effects of low vs. high inertial loads during an eccentric-overload training intervention in rugby union players: a preliminary study

BACKGROUND

Eccentric overload training (EOT) has been proposed as an effective stimulus to optimize dynamic athletic performance. Nevertheless, the appropriate intensity during EOT remains unknown. The purpose of this study was to evaluate the influence of the inertial load used during an EOT program on performance adaptations in rugby union players.

METHODS

Fifteen rugby players were divided into a low (0.025 kg·m2; G 0.025) or a high (0.075 kg·m2; G 0.075) inertial load for training. Both groups trained using the flywheel half squat exercise twice a week during the seven-week EOT. Athletic performance was evaluated by testing the half squat maximum repetition (1RM), countermovement jump (CMJ), 40 m linear sprint, the modified agility T-Test, and power output in the flywheel squat exercise. Data were analysed using magnitude-based inferences.

RESULTS

Both groups improved their 1RM and CMJ to a similar extent. Nevertheless, the G 0.025 showed likely trivial changes in linear sprint (ES=-0.02), and possibly positive effects on the agility T-Test (ES=0.16), while the G 0.075 showed possibly negative effects on 40 m linear sprint (ES=-0.23) and likely trivial effects on the T-Test (ES=0.07).

CONCLUSIONS

Due to the similar gains in 1RM and CMJ, and the superior maintenance in linear sprint, the use of low inertial loads during EOT may be a better option when looking for athletic performance optimization.

The effects of playing two consecutive matches in the shoulder rotational profiles of elite youth badminton players

OBJECTIVE

The aim of the present study was to analyse the effects of playing two badminton matches on the same day on the shoulder profile (i.e., range of motion (ROM) and strength) of young badminton players.

DESIGN

Cross-sectional study.

SETTING

Indoor sports facility.

PARTICIPANTS

Thirty-one elite junior badminton players (age 16.6 ± 1.0 years, body mass 63.9 ± 6.1 kg, height 174.8 ± 6.1 cm), including 19 boys and 12 girls.

MAIN OUTCOME MEASURES

Shoulder passive internal rotation (IR) and external rotation (ER) ROM as well as shoulder IR/ER maximal isometric strength were measured before and after a competition including two competitive matches.

RESULTS

Significant decreases (p < 0.05) were found in the shoulder ROM (i.e., dominant and non-dominant ER ROMs as well as in the dominant and non-dominant total arc of motion [TAM]) in boys, while in girls, significant increases (p < 0.05) were found in the non-dominant ER absolute strength, with significant decreases were found in the non-dominant ER ROM and the non-dominant TAM.

CONCLUSION

Playing two badminton matches on the same day led to gender-specific changes on the shoulder profile (i.e., ROM and strength) of young elite badminton players, with more impact on the shoulder profile of boys compared to girls.

Understanding the impact loading characteristics of a badminton lunge among badminton players

Background

The rapid and repetitive badminton lunges would produce strenuous impact loading on the lower extremities of players and these loading are thought to be the contributing factors of chronic knee injuries. This study examined the impact loading characteristics in various groups of badminton athletes performing extreme lunges.

Methods

Fifty-two participants classified into male skilled, female skilled, male unskilled, and female unskilled groups performed badminton lunge with their maximum-effort. Shoe-ground kinematics, ground reaction forces, and knee moments were measured by using synchronised force platform and motion analysis system. A 2 (gender) x 2 (skill-level) factorial ANOVA was performed to determine the effects of different gender and different playing levels, as well as the interaction of two factors on all variables.

Results

Male athletes had faster approaching speed (male 3.87 and female 1.08 m/s), longer maximum lunge distance (male 1.47 and female 1.16 m), larger maximum (male 215.7 and female 121.65 BW/s) and mean loading rate (male 178.43 and female 81.77 BW/s) and larger peak knee flexion moment (male 0.75 and female 0.69) compared with female athletes (P < 0.001). Unskilled athletes exhibited smaller footstrike angle (skilled 45.78 and unskilled 32.35°), longer contact time (skilled 0.69 and unskilled 0.75 s), larger peak horizontal GRF (skilled 1.61 and unskilled 2.40 BW), smaller mean loading rate (skilled 150.15 and unskilled 110.05 BW/s) and larger peak knee flexion moment (P < .05; skilled 0.69 and unskilled 0.75 Nm/BW) than the skilled athletes. In addition, the interaction indicated greater peak GRF impact in female unskilled athletes compared with female skilled athletes (P < 0.001; female skilled 2.01 and female unskilled 2.95 BW), while there was no difference between male participants (P > 0.05; male skilled 2.19 and male unskilled 2.49 BW).

Conclusions

These data suggested that male athletes and/or unskilled athletes experience greater impact loading rates and peak knee flexion moment during lunge compared with female and skilled athletes, respectively. This may expose them to higher risk of overuse injuries. Furthermore, female unskilled athletes seemed to be more vulnerable to lower extremity injuries.

Muscle strength characteristics of the hamstrings and quadriceps in players from a high-level youth football (soccer) Academy

The objective of this study was to investigate knee muscle strength characteristics in players from a high-level youth football Academy. In total, 110 players (aged 8-15 years) underwent muscle strength assessments carried out by a research physiotherapist using a computer-linked hand-held dynamometer. Results indicated that isometric hamstrings and quadriceps strength increased with age, whereas the isometric hamstring to quadriceps (H/Q) ratio decreased with age. A number of youth football players (n = 20; 18%; 95% CI: 11-27%) demonstrated isometric H/Q ratios of less than 0.60, as well as muscle strength asymmetries between limbs for the hamstrings (n = 40, 36%; 95% CI: 27-46%) and quadriceps (n = 51, 46%; 95% CI 37-56%), potentially increasing injury risk. This study provides new evidence that the isometric H/Q ratio reduces with advancing age during adolescence which may have important implications for junior athlete development and long-term injury prevention in football.

Periodontal status and serum creatine kinase levels among young soccer players: A preliminary report

OBJECTIVES

It is hypothesized that soccer players with periodontal disease exhibit raised serum creatine kinase (CK) levels as compared to those without periodontal disease. We assessed the clinical gingival status and serum CK levels among young soccer players.

MATERIALS AND METHODS

Demographic data were collected through a structured questionnaire. Full mouth bleeding on probing (BOP) and probing pocket depth (PPD) were assessed. Blood samples (4 mL) were collected for measurement of serum CK levels. All blood samples were collected from a vein in the antecubital region. Total CK activities in serum were determined with an optimized spectrophotometric method. Statistical analysis was performed using one-way analysis of variance, and P< 0.05 was considered statistically significant.

RESULTS

Twenty-seven male soccer players volunteered to participate in the present study. The mean age of the participants in Groups 1 (n = 14) and 2 (n = 13) were 18.2 ± 2.3 years and 19.1 ± 0.6 years, respectively. Mean scores of BOP were significantly higher among individuals in Group 2 (56.8%) compared with individuals in Group 1 (19.4%) (P < 0.001). Mean scores of PPD ≥4 mm were significantly higher among subjects in Group 2 (12.1%) as compared to individuals in Group 1 (0.8%) (P < 0.001). Levels of CK were significantly higher among individuals in Group 2 (292.7 U/L) as compared to those in Group 1 (52.3 U/L) (P < 0.01).

CONCLUSION

Increased BOP and PPD are associated with increased serum CK levels in young soccer players.