Training volume and body composition as risk factors for developing jumper's knee among young elite volleyball players

Patellofemoral pain and musculoskeletal features in young pre- and post-pubertal female dancers

The aim of this study was to examine associations between patellofemoral pain (PFP) and musculoskeletal features (such as tendon structure and bone properties) in young (pre- and post-pubertal) female dancers. A total of 49 dancers participated in this study (mean age 13.6 ± 2.9; weight 47.0 ± 13.2; height 153.7 ± 12.9 and body mass index (BMI) 19.4 ± 3.1) and were assessed for the following factors: dance background and Tanner stage through interviews; ultrasonography assessments of bone properties and patellar tendon structure through ultrasonographic tissue characterization and quantitative ultrasound, respectively; and anthropometric measurements, muscle strength, range of motion (ROM), hypermobility and PFP through physical examinations. PFP was found in 49% of the participants. Post-pubertal dancers with no-PFP were found to have greater muscle strength, greater radial and tibial properties, and better tendon structure compared to pre-pubertal dancers with PFP and compared to pre-pubertal dancers with no-PFP [F(2, 41) = 18.64, p < .001; F(2, 41) = 20.46, p < .001; F(2, 41) = 33.06, p < .001; and, F(2, 41) = 6.02, p = .007, respectively]. Logistic regression showed that tibial bone properties and range of movement (ROM) in hip external rotation were significantly associated with PFP [odds ratio (OR) = .889 and OR = 2.653, respectively; Cox & Snell R2 = .701]. The study revealed a high prevalence of PFP among young dancers, with low bone properties and hyperjoint ROM emerging as the main factors that are related to PFP. These findings should be addressed by medical teams, athletic trainers, and dance teachers regarding the need for implementing modifications to dance training programmes and injury-prevention strategies in young pre-pubertal dancers.

A New Training Load Quantification Method at Supramaximal Intensity and Its Application in Injuries Among Members of an International Volleyball Team

ABSTRACT

Bouzigues, T, Maurelli, O, Imbach, F, Prioux, J, and Candau, R. A new training load quantification method at supramaximal intensity and its application in injuries among members of an international volleyball team. J Strength Cond Res 38(8): 1453-1463, 2024-The quantification of training loads (TLs) is essential for optimizing jump performance and reducing the occurrence of injuries. This study aimed to (a) propose a new method for quantifying TLs in explosive exercises, (b) determine the nature of the relationship between TLs dynamics and injury occurrence, and (c) assess a TL critical for training schedule purposes, above which the risk of injury occurrence becomes unacceptable. This study was conducted with 11 male volleyball players on a national team during a 5-month international competitive period. The proposed new method for quantifying TLs is based on a weighting factor applied to relative jumping intensities, determined by the number of sustainable jumps and their intensities measured by G-Vert accelerometer. The relationship between TLs dynamics and injury occurrence was assessed using a variable dose-response model. A high coefficient of determination was found between the maximum number of jumps possible and their intensities ( r2 = 0.94 ± 0.14, p < 0.001), indicating a strong physiological relationship between jumping intensities and the constraints imposed. The occurrence of injury was dependent on TLs dynamics for 2 players ( r2 = 0.26 ± 0.01; p < 0.001). The TL critical corresponded to 11 jumps over 80% of maximum jump height during games and approximately 130 jumps at <80% of maximal jump height. The present study proposes a new approach for quantifying supramaximal exercises and provides tools for training schedules and the prevention of volleyball injuries.

Differences in anthropometric and vertical jump force-time characteristics between U16 and U18 female basketball players

Considering the importance of body composition and lower-body strength and power for basketball players' on-court performance, as well as a lack of sports science research focused on female athletes, the purpose of the present investigation was to record the anthropometric and countermovement vertical jump (CMJ) characteristics of top-tier U16 and U18 female basketball players and examine between-group differences in the aforementioned tests. Thirty-two athletes who were a part of the national basketball academy volunteered to participate in the present investigation. Following the body composition assessment conducted via a segmental multifrequency bioimpedance analyzer, athletes performed three CMJs while standing on a force plate system sampling at 1000 Hz. Independent t-test and Mann-Whitney U-test were used to examine between-group differences. The findings reveal significant differences in body composition and lower-body neuromuscular performance characteristics between female basketball players ages 16 and 18. Although no differences were observed in muscle and body fat percentages, the U18 group had significantly greater height, overall body mass (both muscle and fat mass), as well as greater segmental fat-free mass (trunk, both legs and arms), intracellular and extracellular water, and body mass index when compared to their U16 counterparts. On the other hand, the U18 group demonstrated longer eccentric, concentric, and braking phase duration, as well as overall contraction time when compared to the U16 players. In addition, the U18 athletes exhibited higher eccentric mean force and power, concentric impulse, peak power, and mean and peak force.

Prevalence and associated factors of non-traumatic knee pain in high school volleyball players: a cross-sectional study

OBJECTIVES

This study aimed to determine the prevalence of knee pain among high school volleyball attackers, identify associated factors, and explore the relationship between knee pain and lower back pain (LBP).

METHODS

A cross-sectional study involving 82 high school volleyball attackers (15-17 years) used questionnaires, interviews, and field-based assessments to collect data on demographics, volleyball-specific factors, flexibility, and jumping ability. Logistic regression analysis was used to identify factors associated with knee pain.

RESULTS

The prevalence of knee pain was 19.5%. Factors significantly associated with knee pain were a history of LBP (OR, 4.64; 95% CI, 1.28 to 16.8; p = 0.019) and flexibility determined by the absolute difference in heel-buttock distance (OR, 1.37; 95% CI, 1.02 to 1.83; p = 0.037). Participants with knee pain had more volleyball experience and a higher proportion of players who competed as starters in the previous year. Both groups reported approximately 18 hours of practice per week during the school year and around 27 hours during school holidays, with no significant difference observed.

CONCLUSION

Factors associated with knee pain include a history of LBP and reduced flexibility on the heel-buttock distance test. The study highlights the need for a comprehensive approach, considering the coexistence of LBP and focusing on improving anterior thigh flexibility.

Differences in training load, jump performance and injury occurrence in elite youth volleyball players

BACKGROUND

External and internal training load are used to monitor training effects in volleyball. Occurrence of injuries in volleyball is dependent of training loads and state of fitness but also playing positions and gender. This study aims to investigate the impact of gender and playing positions on injury occurrence among young volleyball players, considering both training loads and fitness levels.

METHODS

Conducted from September 2021 to May 2022, this study involved 37 elite young volleyball players, comprising 16 female (176.8±3.6 cm; 65.3±5.7 kg; 13.9±1.1 years old) and 21 males (189.6±7.3 cm; 77.4±9.5 kg; 14.7±1.2 years old). G-Vert accelerometer was used to quantify training load. During these sessions, RPE, state of fitness and occurrence of injuries, were collected using a daily questionnaire.

RESULTS

The primary findings indicate that males demonstrated a higher number of jumps, mean intensity, mean training load per session, and reported higher fitness levels compared to females (P<0.001). However, females were more injured than males (P<0.001). Setters were identified as the players with the highest jump frequency, albeit at lower heights and intensities than their counterparts (P<0.001). Among males, middle blockers exhibited the highest mean intensity and training load per session (P<0.01).

CONCLUSIONS

The elevated frequency of injuries and a worse reported fitness levels among females, despite lower training loads, suggests a potential deficiency in physical preparation among young women, particularly in terms of their ability to perform repeated high-intensity jumps.

Causal inference did not detect any effect of jump load on knee complaints in elite men's volleyball

The aim was to determine how jump load affects knee complaints in elite men's volleyball. We collected data from four men's premier league volleyball teams through three seasons in a prospective cohort study (65 players, 102 player-seasons). Vert inertial measurement devices captured the jump load (jump frequency and jump height) from 21 088 daily player sessions, and knee complaints were reported in 3568 weekly OSTRC-O questionnaires. Mixed complementary log-log regression models described the probability of (i) experiencing symptoms if players were currently asymptomatic, (ii) worsening symptoms if players had symptoms, and (iii) recovery from knee complaints. Based on our causal assumptions, weekly jump load was modeled as the independent variable, adjusted for age (years), weight (kg), position on volleyball team, and past jump load. No certain evidence of an association was found between weekly jump load and probability of (i) knee complaints (p from 0.10 to 0.32 for three restricted cubic splines of load), (ii) worsening symptoms if the player already had symptoms (p from 0.11 to 0.97), (iii) recovery (p from 0.36 to 0.63). The probability of knee complaints was highest for above-average weekly jump load (~1.2% for an outside hitter with mean age and height) compared with low loads (~1%) and very high loads (→ ~ 0%). The association between jump load and knee complaints risk remains unclear. Small differences in risk across observed jump load levels were observed. It would likely require substantially increased sample sizes to detect this association with certainty.

Differences in external load among indoor and beach volleyball players during elite matches

The aim of this cross-sectional study was to examine relationships of external load variables between beach and indoor volleyball amongst individual positions on the team. The movements of eight beach and fourteen indoor female volleyball players were recorded during elite playoff matches; in total, 2,336 three-dimensional trajectories were analyzed. Time-outs and intervals between rallies or sets were excluded from active play time. In both beach and indoor volleyball, 80% of rallies lasted up to 10 s, and players covered 4.5 to 10 m of court during 60% of rally play. Differences in dependent variables of external load were found between independent variables of sports and player positions (p < 0.05). The distance covered in beach volleyball rallies and Player Load™ parameters was significantly higher by up to 23%. The unstable court surface with sand in beach volleyball elevated explosive Player Load™ (accelerations in all three orthogonal planes of motion higher than 3.5 m/s3) in beach volleyball players compared to those of players on stable flooring in indoor. While beach volleyball blocker and defender positions showed no significant difference in parameters between each other, they differed in all parameters when compared to player positions in indoor volleyball. Indoor blocker and libero reached higher loads than setter, outside and opposite positions in various parameters. Factors that influence external load include the larger relative court areas covered by each player in beach volleyball, complexity of players' roles, and game strategy. This data adds to the knowledge of elite match demands in female volleyball. Specified agility-drill distances and times are essential for training optimization and must be supported by scientific observation. Researchers, coaches, and conditioning specialists should find this helpful for achieving a higher degree of training regulation.

Body Fat of Basketball Players: A Systematic Review and Meta-Analysis

Background

This study aimed to provide reference values for body fat (BF) of basketball players considering sex, measurement method, and competitive level.

Methods

A systematic literature research was conducted using five electronic databases (PubMed, Web of Science, SPORTDiscus, CINAHL, Scopus). BF values were extracted, with analyses conducted using random-effects models and data reported as percentages with 95% confidence intervals (CI).

Results

After screening, 80 articles representing 4335 basketball players were selected. Pooled mean BF was 13.1% (95% CI 12.4–13.8%) for male players and 20.7% (95% CI 19.9–21.5%) for female players. Pooled mean BF was 21.4% (95% CI 18.4–24.3%) measured by dual-energy X-ray absorptiometry (DXA), 15.2% (95% CI 12.8–17.6%) via bioelectrical impedance analysis (BIA), 12.4% (95% CI 10.6–14.2%) via skinfolds and 20.0% (95% CI 13.4–26.6%) via air displacement plethysmography. Pooled mean BF across competitive levels were 13.5% (95% CI 11.6–15.3%) for international, 15.7% (95% CI 14.2–17.2%) for national and 15.1% (95% CI 13.5–16.7%) for regional-level players. As the meta-regression revealed significant effects of sex, measurement method and competitive level on BF, the meta-analysis was adjusted for these moderators. The final model revealed significant differences in BF between male and female players (p < 0.001). BF measured by DXA was significantly higher than that measured by BIA or skinfolds (p < 0.001). International-level players had significantly lower BF than national and regional-level players (p < 0.05).

Conclusions

Despite the limitations of published data, this meta-analysis provides reference values for BF of basketball players. Sex, measurement method and competitive level influence BF values, and therefore must be taken into account when interpreting results.

Association between Body Weight and Body Mass Index and Patellar Tendinopathy in Elite Basketball and Volleyball Players, a Systematic Review and Meta-Analysis

The features of Patellar-Tendinopathy are (1): pain localised to the inferior pole of the patellar; (2): the presence of load-related pain. Body-Weight and Body-Mass-Index, as two easily-measured variables, could potentially aid the prediction of PT. This review aims to establish relationships between Body-Weight and Body-Mass-Index and Patellar-Tendinopathy via synthesising the evidence from prospective-cohort and cross-sectional studies in elite basketball and volleyball players. Seven databases (PubMed, EMBASE, CINAHL, Google Scholar, Health-Management-Information-Consortium, National-Technical-Information-Service, ClinicalTrial.gov) and citation chasing were used to identify English peer-review articles from 2000 to 2022. An adapted version of the Newcastle-Ottawa scale was used for critical appraisal. Two reviewers were involved in literature searching, data extraction, and quality review. Two prospective cohort and five cross-sectional studies met the inclusion criteria, providing 849 subjects (male:female: 436:413). Five studies found BW is associated with PT. Three studies found a relationship between BMI and PT. Six out of seven studies were classified as very good studies. All studies were level IV evidence. The very low certainty evidence suggests an association between BW and PT. There is moderate certainty evidence that BMI is associated with PT. These preliminary findings should be treated cautiously due to the lack of strong evidence.

Consequences of Patellar Tendinopathy on Isokinetic Knee Strength and Jumps in Professional Volleyball Players

Patellar tendinopathy (PT) in professional volleyball players can have an impact on their careers. We evaluated the impact of this pathology in this specific population in terms of isokinetic strength and jumping performances. Thirty-six professional male volleyball players (mean age: 24.8 ± 5.2) performed isokinetic knee assessments, single-leg countermovement jumps and one leg hop test. They filled out the Victorian Institute of Sport Assessment-Patella (VISA-P) score. Two groups were assessed: “PT group” (n = 15) and “control group” (n = 21). The VISA-P score was lower in the PT group (p < 0.0001). No difference was found between the isokinetic strength limb symmetry index and the jump performance limb symmetry index. The healthy legs of the control group were compared with the affected (PT+) and the unaffected legs (PT−) of the PT group. Compared with the healthy legs, both PT+ and PT− legs showed decreased values of quadriceps and hamstring strengths. Only PT+ legs scored lower than healthy legs in countermovement jumps and hop tests. No differences were found between PT+ and PT− legs for muscle strengths and jumps. A low correlation existed between quadriceps strength and jumping performances (r > 0.3; p < 0.001). Volleyball players with PT showed a decrease in the isokinetic knee strength. This strength deficit was found both on the symptomatic legs and the asymptomatic ones. Jumps were only significantly altered on the pathological legs. Highlighting that the unaffected limbs were also impaired in addition to the affected limbs may help provide a better adaptation of the rehabilitation management.

Knee dynamics during take-off and landing in spike jumps performed by volleyball players with patellar tendinopathy

[Purpose] Patellar tendinopathy is a common sports injury. The risk factors for this injury can be categorized as intrinsic, extrinsic, and dynamic. We examined the dynamic factors in this study. [Participants and Methods] The participants were volleyball players who were assigned to a patient group (n=6) if they had medial patellar tendinopathy in the left knee or to a control group (n=7) otherwise. The participants performed spike jumps, and their ground reaction force and three-dimensional kinematic data were recorded. Knee angle and moment data were extracted at the peak extension moment of take-off and landing. [Results] The two groups showed no differences in knee angles. A tendency for abduction/external rotation moments at take-off and landing on both sides was observed in the control group, while the patient group showed adduction and internal rotation moments at take-off and adduction moment at landing in the left (injured) knee. [Conclusion] The observed knee joint moments in the left (injured) knee of the patient group may have been involved in the pathophysiological mechanism underlying the development of patellar tendinopathy.

Isokinetic and Isometric Assessment of the Knee Joint Extensors and Flexors of Professional Volleyball Players

Purpose: The main objective of this study was to evaluate the level of muscle strength by using isokinetic and isometric measurements—more specifically, the force ratio between the knee flexors and extensors (values of the torques). Methods: An experimental group of elite volleyball players (n = 14) were compared to a control group (n = 14) of healthy non-athletes of comparable ages. Torque measurements were obtained under three concentric conditions (angular velocities of 60 °/s, 180 °/s, and 300 °/s) and one static condition by utilizing the Biodex System 3. Results: In all trials, the volleyball players achieved significantly higher peak torque (PT) values for both the extensors and flexors (p < 0.05) than those of the control group. However, the strength ratio of the flexors and extensors (H/Q) in the experimental group was only 83% of the standard reported in the literature. The most developed and dominating muscles in the knee joints of the volleyball players were the extensors, which accounted for the low strength ratio and dynamic instability of this joint. Conclusion: Based on a proper assessment of the strength ratio of the knee flexors and extensors, properly selected and implemented resistance training can improve the maximum strength and power production and reduce the incidence of injuries in volleyball.

Impact of Patellar Tendinopathy on Isokinetic Knee Strength and Jumps in Professional Basketball Players

Patellar tendinopathy is characterized by tendon pain which may reduce the level of performance. This study's main aim was to compare isokinetic knee strength and jump performances at the start of the sport season between players with patellar tendinopathy and those without. Secondary aims were to assess the relationship between knee strength and jump function. Sixty-two professional basketball players were enrolled (mean age: 25.0 ± 4.0). All players performed knee isokinetic measurements, single leg countermovement jumps, and one leg hop tests. Correlations between knee strength and jump performances were examined. Twenty-four players declared a patellar tendinopathy and were compared to the 38 players without tendinopathy. The isokinetic quadriceps strength was lower in cases of patellar tendinopathy, and a camel's back curve was observed in 58% of the cases of patellar tendinopathy. However, jump performances were preserved. No link was found between quadriceps and hamstring limb symmetry indexes at 60 and 180°/s with jumps. This preseason screening enabled us to identify the absence of consequences of patellar tendinopathy in professional basketball players. Jump performances were not altered, possibly due to compensatory strategies.

Chronic hyperglycemia, hypercholesterolemia, and metabolic syndrome are associated with risk of tendon injury

Tendon injury is a considerable problem affecting both physically active and sedentary people. The aim of this study was to examine the relationship between markers for metabolic disorders (hyperglycemia, hypercholesterolemia, and metabolic syndrome) and the risk of developing tendon injuries requiring referral to a hospital. The Copenhagen City Heart Study is a prospective study of diabetic and non-diabetic individuals from the Danish general population with different physical activity levels. The cohort was followed for 3 years via national registers with respect to tendon injuries. Data from 5856 individuals (median age 62 years) were included. The overall incidence of tendon injury in both upper and lower extremities that required an out-patient or in-house visit to a hospital was ~5.7/1000 person years. Individuals with elevated HbA1c (glycated hemoglobin) even in the prediabetic range (HbA1c>5.7%) had a ~3 times higher risk of tendon injury in the lower extremities only, as compared to individuals with normal HbA1C levels. Hypercholesterolemia (total cholesterol>5 mmol/L) increased risk of tendon injury in the upper extremities by ~1.5 times, and individuals with metabolic syndrome had ~2.5 times higher risk of tendon injury in both upper and lower extremities. In conclusion, these data demonstrate for the first time in a large cohort with different physical activity levels that the indicators for metabolic syndrome are a powerful systemic determinant of tendon injury, and two of its components, hyperglycemia and hypercholesterolemia, each independently make tendons susceptible for damage and injury.

Magnitude, Frequency, and Accumulation: Workload Among Injured and Uninjured Youth Basketball Players

Overuse injuries are common in basketball. Wearable technology enables the workload to be monitored in sport settings. However, workload-injury models lack a biological basis both in the metrics recorded and how workload is accumulated. We introduce a new metric for monitoring workload: weighted jump height, where each jump height is weighted to represent the expected effect of the jump magnitude on damage to the tendon. The objectives of this study were to use principal components analysis to identify distinct modes of variation in all workload metrics accumulated over 1, 2, 3, and 4 weeks and to examine differences among the modes of variation in workload metrics between participants before the injury and uninjured participants. Forty-nine youth basketball players participated in their typical basketball practices and games, and lower extremity injuries were classified as patellar or Achilles tendinopathy, other overuse, or acute. An inertial measurement unit recorded the number and height of all jumps, and session rating of perceived exertion was recorded. The previous 1-, 2-, 3-, and 4-week workloads of jump count, jump height, weighted jump height, and session rating of perceived exertion were summed for each participant-week. Principal components analysis explained the variance in the accumulated workload variables. Using the retained principal components, the difference between the workload of injured participants in the week before the injury and the mean workload of uninjured participants was described for patellar or Achilles tendinopathy, overuse lower extremity injury, and any lower extremity injury. Participants with patellar or Achilles tendinopathy and overuse lower extremity injuries had a low workload magnitude for all variables in the 1, 2, 3, and 4 weeks before injury compared with the weeks before no injury. Participants with overuse lower extremity injuries and any lower extremity injury had a high previous 1-week workload for all variables along with a low previous 3- and 4-week jump count, jump height, and weighted jump height before injury compared with the weeks before no injury. Weighted jump height represents the cumulative damage experienced by tissues due to repetitive loads. Injured youth basketball athletes had a low previous 3- and 4-week workloads coupled with a high previous 1-week workload.

Failed Surgery for Patellar Tendinopathy in Athletes: Midterm Results of Further Surgical Management

Background:

Tendon injuries are commonly seen in sports medicine practice. Many elite players involved in high-impact activities develop patellar tendinopathy (PT) symptoms. Of them, a small percentage will develop refractory PT and need to undergo surgery. In some of these patients, surgery does not resolve these symptoms.

Purpose:

To report the clinical results in a cohort of athletes who underwent further surgery after failure of primary surgery for PT.

Study Design:

Case series; Level of evidence, 4.

Methods:

A total of 22 athletes who had undergone revision surgery for failed surgical management of PT were enrolled in the present study. Symptom severity was assessed through the Victorian Institute of Sport Assessment Scale for Patellar Tendinopathy (VISA-P) upon admission and at the final follow-up. Time to return to training, time to return to competition, and complications were also recorded.

Results:

The mean age of the athletes was 25.4 years, and the mean symptom duration from the index intervention was 15.3 months. At a mean follow-up of 30.0 ± 4.9 months, the VISA-P score improved 27.8 points (P < .0001). The patients returned to training within a mean of 9.2 months. Fifteen patients (68.2%) returned to competition within a mean of 11.6 months. Of these 15 patients, a further 2 had decreased their performance, and 2 more had abandoned sports participation by the final follow-up. The overall rate of complications was 18.2%. One patient (4.5%) had a further revision procedure.

Conclusion:

Revision surgery was feasible and effective in patients in whom PT symptoms persisted after previous surgery for PT, achieving a statistically significant and clinically relevant improvement of the VISA-P score as well as an acceptable rate of return to sport at a follow-up of 30 months.

Relationship of Patellofemoral Angles and Tibiofemoral Rotational Angles With Jumper's Knee in Professional Dancers: An MRI Analysis

Background:

Jumper’s knee is a type of tendinopathy affecting the distal insertion of the quadriceps tendon (25% of cases) or the patellar tendon. It has been shown that frontal-plane measurements, such as genu valgum, genu varum, an increased quadriceps angle, a protuberant tibial tuberosity, patella alta, and short hamstring muscles, may be related to jumper’s knee.

Purpose:

To investigate the effects of tibiofemoral rotational angles and patellofemoral (PF) angles on the development of jumper’s knee in professional folk dancers.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

We examined 26 dancers (16 male, 10 female) with knee pain using magnetic resonance imaging (MRI), for a total of 32 knees. Of the knees, 21 with quadriceps tendinopathy (QT) and 7 with patellar tendinopathy (PT) were detected. Using MRI scans, we measured PF angles (PF sulcus angle, lateral PF angle, patellar tilt angle, lateral trochlear inclination angle, lateral patellar tilt angle, and PF congruence angle) and tibiofemoral rotational angles (condylar twist angle, posterior condylar angle, femoral Insall angle, tibial Insall angle, posterior tibiofemoral angle, and angle between the Whiteside line and posterior femoral condylar line) and noted specifics such as patella alta, patella baja, and the Wiberg classification of the patellar shape between the patients with versus without QT and between patients with versus without PT to understand if there was any relationship with tendinopathy.

Results:

No statistically significant difference was observed in age, sex, patella alta, or the Wiberg classification between the QT groups (with vs without) and between the PT groups (with vs without) (P > .05). Having QT was found to be significantly associated with the PF sulcus angle (P = .009), and having PT was found to be significantly associated with the femoral Insall angle (P = .029).

Conclusion:

Jumper’s knee was found to be associated with anatomic variations of the PF sulcus angle and rotation of the patellar tendon in relation to the femur (femoral Insall angle) on axial MRI scans in professional dancers. Unlike those of other athletes, dancers’ knees are exposed more to external rotation forces because of turnout, and this can be the cause of jumper’s knee.

High-Impact Details of Play and Movements in Female Basketball Game

This study aimed to identify the high-impact details of play and movements with higher acceleration and their frequency during a female basketball match. Trunk acceleration was measured during a simulated basketball game with eight female players. The extracted instance was categorized, which generated at > 6 and 8 G resultant accelerations using a video recording and an accelerometer attached to the players’ trunk, as details of play and movements. The frequency and ratio of the details of play and movements regarding all detected movements were calculated. A total of 1062 and 223 play actions were detected for the resultant acceleration thresholds of > 6 and 8 G, respectively. For these acceleration thresholds, in terms of details of play, positioning on the half-court was the most frequently observed (29.6 and 23.8%, respectively). In terms of movements, deceleration was the most frequently detected movement (21.5 and 23.3%, respectively), followed by landing (7.6 and 15.7%, respectively). Deceleration during positioning on the half-court and defense as well as landing mostly after a shot were detected as high-impact frequent basketball-specific movements. The results also showed that characteristics of movements or playing style and playing position may have an effect on acceleration patterns during a basketball game.

The Influence of a 14-Week Infantry Commanders Courses on the Achilles Tendon and Patellar Tendon Structure

INTRODUCTION

Alternated tendon structure may raise stress to the musculoskeletal structures and may increase the potential for overuse injury. Screening the tendon structure of soldiers pre- and post-participation in a strenuous combat course is essential. The aim of the present study was to investigate the influence of a 14-week infantry commanders courses on the Achilles tendon (AT) structure and patellar tendon (PT) structure in combat soldiers.

MATERIALS AND METHODS

Ninety-eight participants from an infantry commanders course were screened pre- and post-course for the AT and PT structures, using ultrasonographic tissue characterizaton (UTC) imaging to capture a 3D structure of four echo-type fibers (I-IV).

RESULTS

In both tendons, the mean relative frequency of echo-type I fibers significantly decreased from pre- to post-testing, with a significant increase in the relative frequency of echo-types II, III, and IV fibers. In the AT, 60.2% of the subjects showed positive differences (between pre- and post-testing in the echo-type III + IV fiber ("worsened" tendon structure), whereas in the PT, 92.2% of the subject showed an increased frequency. No significant correlation (r = 0.108; P = .324) was found between the differences of echo-type III + IV fibers of the AT and that of the PT.

CONCLUSIONS

Loads to the musculoskeletal structures along the combat course increased the mean relative frequency of the "reduced" echo-type fibers (III + IV) in both the AT structure and the PT structure. Yet, whereas in the AT around 40% of the soldiers showed an improved tendon structure along the course, in the PT less than 10% of the soldiers showed that improvement. Soldiers and commanders should be aware of the different influence of the loading exercises along the course on the AT and on the PT structure, as "reduced" tendons structure might put the soldiers at higher risk for injury in the future.

The effect of long-term volleyball training on the level of somatic parameters of female volleyball players in various age categories

Volleyball is an exceedingly popular physical activity in the adolescent population, especially with females. The study objective was to assess the effect of volleyball training and natural ontogenetic development on the somatic parameters of adolescent girls. The study was implemented in a group of 130 female volleyball players (aged 12.3 ± 0.5 – 18.1 ± 0.6 years) along with 283 females from the general population (aged 12.3 ± 0.5 – 18.2 ± 0.5 years). The measured parameters included: body height (cm), body mass (kg), body fat (kg, %), visceral fat (cm²), body water (l), fat free mass (kg) and skeletal muscle mass (kg, %). Starting at the age of 13, the volleyball players had significantly lower body fat ratio and visceral fat values than those in the general population (p < 0.001 in body fat % and p < 0.01 in visceral fat). In volleyball players, the mean body fat (%) values were 17.7 ± 6.6 in 12-year-old players, 16.7 ± 4.9 in 13-year-old players, 18.5 ± 3.9 in 16-year-old players, and 19.3 ± 3.1 in 18-year-old players. In the general population, the mean body fat (%) values were 19.6 ± 6.3 in 12-year-old girls, 21.7 ± 6.4 in 13-year-old girls, 23.4 ± 6.1 in 16-year-old girls, and 25.8 ± 7.0 in 18-year-old girls. The visceral fat (cm²) mean values were 36.4 ± 19.3 in 12-year-old players, 39.2 ± 16.3 in 13-year-old players, 45.7 ± 14.7 in 16-year-old players, and 47.2 ± 12.4 in 18-year-old players. In the general population, the mean visceral fat (cm²) values were 41.4 ± 21.1 in 12-year-old girls, 48.4 ± 21.5 in 13-year-old girls, 58.0 ± 24.7 in 16-year-old girls, and 69.1 ± 43.7 in 18-year-old girls. In volleyball players, lower body fat ratio corresponded with a higher skeletal muscle mass ratio. The differences found in skeletal muscle mass ratio were also significant starting at the age of 13 (p < 0.001). The mean skeletal muscle mass (%) values were 44.1 ± 3.4 in 12-year-old volleyball players, 45.4 ± 2.5 in 13-year-old players, 45.0 ± 2.2 in 16-year-old players, and 44.7 ± 1.8 in 18-year-old players. In the general population, the mean skeletal muscle mass (%) values were 42.8 ± 3.2 in 12-year-old girls, 42. ± 4.1 in 13-year-old girls, 41.9 ± 3.3 in 16-year-old girls, and 40.6 ± 3.7 in 18-year-old girls. Differences in body composition between the individual age groups were similar between the volleyball players and girls in the general population. The results indicate that regular volleyball training influences the body composition of young females however the development of body composition parameters is subject to their ontogenetic development.

Can Achilles and patellar tendon structures predict musculoskeletal injuries in combat soldiers?

Aiming to investigate whether Achilles tendon (AT) structure and patellar tendon (PT) structure are risk factors for musculoskeletal injuries in combat soldiers, 168 participants were recruited from an infantry commander's course. The AT and PT were examined pre-course using UTC to capture the structure of four echo-type fibers (I-IV). All injuries were assessed by military physicians pre-course and throughout the 14-week course. Soldiers who were injured during the course had a significantly higher pre-course prevalence of AT and PT echo-type III and echo-type IV compared to soldiers that were not injured during the course. Variables that were found to be associated with injured/non-injured participants were echo-type III + IV of the PT (OR = 1.44, 95% CI = 1.24-1.68) and echo-type III of the AT (OR = 1.69, 95% CI = 1.35-2.12). ROC analyses showed that the best model, exhibiting both high sensitivity and low specificity, was that participants with PT echo-type III + IV > 10% or AT echo-type III >8.5% had the highest risk of being injured during the course. In conclusions, the tendon structure at the beginning of high-intensity activity or physical training program might be a risk factor for subsequent injury during the course. Soldiers and high-level athletes should be aware of the cutoff points for fiber types in tendon structure that might put them at high risk for future injury. At-risk soldiers/athletes should be provided with an intervention program before they start their training program, with the aim of improving the tendon structure and preventing subsequent injury.

Validation of a commercially available inertial measurement unit for recording jump load in youth basketball players

A high incidence of overuse knee injuries among youth basketball players may be attributed to number of jumps. Wearable technology may be an effective tool for measuring jump load compared to traditional counting methods. The purpose of this study was to validate a commercially available jump counter (VERT® Classic) in youth basketball practices and games, and to identify the characteristics (i.e., height, direction, takeoff) of jumps recorded by the VERT® Classic. 46 (19F, 27M) youth basketball players wore a VERT® Classic and were recorded on video during games and practices. The number of jumps recorded by the VERT® Classic and evaluated by video raters were compared for each jump characteristic using intraclass correlation coefficient (ICC(3,k)), mean offset, and limits of agreement. The number and percent of VERT® Classic jumps and corresponding video jumps according to timestamp were reported. VERT® Classic jumps had excellent reliability with video-counted jumps over 15 cm (ICC(3,k) = 0.958), with a mean offset of -2.4 jumps (fewer VERT® Classic) and limits of agreement -12.6 to 7.8 jumps. Pairs of corresponding jumps represented 68.0% of total video jumps and 92.0% of VERT® Classic jumps. The VERT® Classic can provide an estimate of jump load in youth basketball.

Injuries associated with Japanese high-school men's volleyball: a two-year survey and analysis

[Purpose] There are many factors associated with sports injuries in volleyball that remain unclear; therefore, many of these injuries are still not being effectively prevented. This study aimed to help effectively prevent injuries among and provide conditioning guidance to participants of a high-school men's volleyball team. [Participants and Methods] The participants were 36 males of a high-school men's volleyball team, and the circumstances of injury occurrence, injury type, injury site, exposure time, and injury rate per 1,000 player-hours were evaluated among these participants. [Results] Over the 2 year period, 68 injuries occurred, and the injury rate was 1.51/1,000 player-hours. Specifically, the injuries comprised 40 cases of trauma (58.8%) and 28 cases of disorders (41.2%). Additionally, injuries occurring during training tended to be disorders, and injuries occurring during matches tended to be traumas. The most common site of injury was the ankle joint. [Conclusion] The results suggest that it is important for players to have appropriate knowledge about the injuries, acquire accurate form, and undergo various types of site-specific training in order to prevent injury. In the future, the causes and circumstances of occurrence of injury must be verified in a larger number of participants.

Patellar tendon structure responds to load over a 7-week preseason in elite male volleyball players

The purpose of this study was to investigate the relation between external and internal load and the response of the patellar tendon structure assessed with ultrasound tissue characterization (UTC) in elite male volleyball players during preseason. Eighteen players were followed over 7 weeks, measuring four load parameters during every training and match: volume (minutes played), rating of perceived exertion (RPE) (ranging from 6 to 20), weekly load (RPE*volume), and jump frequency (number of jumps). Patellar tendon structure was measured biweekly using UTC, which quantifies tendon matrix stability resulting in four different echo types (I-IV). On average, players spent 615 min/wk on training and matches with an RPE of 13.9 and a jump frequency of 269. Load evaluation shows significant changes over the 7 weeks: Volume and weekly load parameters were significantly higher in week 3 than week 7 and in week 4 than week 2. Weekly load performed in week 4 was significantly higher than week 7. No significant changes were observed in tendon structure. On the non-dominant side, no significant correlations were found between changes in load parameters and echo types. At the dominant side, a higher weekly volume and weekly load resulted in a decrease of echo type I and a higher mean RPE in an increase of echo type II. The results of this study show that both external and internal load influence changes in patellar tendon structure of elite male volleyball players. Monitoring load and the effect on patellar tendon structure may play an important role in injury prevention.

The presence of patellar tendinopathy in the bone-patellar tendon-bone autograft may increase the risk of anterior cruciate ligament graft failure

PURPOSE

The purpose of this study was to evaluate the influence of patellar tendinopathy on primary anterior cruciate ligament (ACL) reconstruction graft failure when using bone-patellar tendon-bone (BPTB) autograft.

METHODS

All patients undergoing primary ACL reconstruction using ipsilateral BPTB with preoperative magnetic resonance imaging (MRI) available for review were approached for eligibility. The medical charts of included patients were reviewed to obtain demographic information, anatomical characteristics, injury characteristics, treatment characteristics, length of follow-up, and presence of graft failure. A single, fellowship-trained, knee-specialist and blinded researcher performed preoperative MRI interpretation of patellar tendinopathy. The presence/absence of patellar tendinopathy (none, mild, moderate, or severe changes) was compared between patients with (cases) and without (controls) failure of ACL reconstruction. There were 559 cases with a median (range) clinical follow-up was 8 (4-30) months and an average age of 21.5 years (82% males).

RESULTS

Of the 559 cases, there were 182 (32.6%) with and 377 (67.4%) without patellar tendinopathy. A total of 32 (5.7%) graft failures occurred. There were a significantly higher failure rate in patients with compared to without patellar tendinopathy (p < 0.001), and in patients with compared to without partial tendon tear (p < 0.001). The odds ratio (95% confidence interval) for graft failure was 5.9 (2.7-13.1), 20.8 (6.8-63.9) and 54.4 (5.5-539.4) in patients with patellar tendinopathy (compared to absence of patellar tendinopathy), moderate or severe patellar tendinopathy (compared to none or mild patellar tendinopathy), or partial tendon tear (compared to absence of tendon tear), respectively.

CONCLUSION

The presence of patellar tendinopathy increases the risk of BPTB graft failure when used for ACL reconstruction. The use of BPTB autograft is not recommended if patellar tendinopathy is obvious or there are suspicious of partial tendon tear on MRI. In such cases, the surgeon should consider using a different graft.

LEVEL OF EVIDENCE

Retrospective cohort analysis, Level III.

Time-to-event analysis for sports injury research part 1: time-varying exposures

BACKGROUND

'How much change in training load is too much before injury is sustained, among different athletes?' is a key question in sports medicine and sports science. To address this question the investigator/practitioner must analyse exposure variables that change over time, such as change in training load. Very few studies have included time-varying exposures (eg, training load) and time-varying effect-measure modifiers (eg, previous injury, biomechanics, sleep/stress) when studying sports injury aetiology.

AIM

To discuss advanced statistical methods suitable for the complex analysis of time-varying exposures such as changes in training load and injury-related outcomes.

CONTENT

Time-varying exposures and time-varying effect-measure modifiers can be used in time-to-event models to investigate sport injury aetiology. We address four key-questions (i) Does time-to-event modelling allow change in training load to be included as a time-varying exposure for sport injury development? (ii) Why is time-to-event analysis superior to other analytical concepts when analysing training-load related data that changes status over time? (iii) How can researchers include change in training load in a time-to-event analysis? and, (iv) Are researchers able to include other time-varying variables into time-to-event analyses? We emphasise that cleaning datasets, setting up the data, performing analyses with time-varying variables and interpreting the results is time-consuming, and requires dedication. It may need you to ask for assistance from methodological peers as the analytical approaches presented this paper require specialist knowledge and well-honed statistical skills.

CONCLUSION

To increase knowledge about the association between changes in training load and injury, we encourage sports injury researchers to collaborate with statisticians and/or methodological epidemiologists to carefully consider applying time-to-event models to prospective sports injury data. This will ensure appropriate interpretation of time-to-event data.

Evaluation of Intrinsic Biomechanical Risk Factors in Patellar Tendinopathy: A Retrospective Radiographic Case-Control Series

Background

Patellar tendinopathy is an overuse condition often affecting athletes. It has been postulated that patellar tendinopathy is associated with patella alta; however, this and any other anatomic risk factors have not been identified.

Purpose

To explore whether lever arm differences from radiographic measurements exist between patients with and without tendinopathy. This may provide surgeons with a simple radiographic means to identify patients at risk.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

Magnetic resonance imaging scans of the knee from a sports imaging facility were screened and reviewed to identify 2 groups of patients: those with and those without imaging signs of patellar tendinopathy. The lateral radiographs were reviewed and measurements made to determine (1) lever arm ratio, (2) moment arm ratio, (3) angle between the moment and line of pull of the patellar tendon, (4) patellar tendon pivot point angle, and (5) patellar height (alta). Measurements were obtained directly from radiographs. The images and measurements were reviewed by 2 experienced orthopaedic clinicians.

Results

A total of 105 patients were included in this study: 52 with patellar tendinopathy and 53 without patellar tendinopathy (controls). The mean age was similar between groups (23 years); females accounted for 8 of 52 patients with patellar tendinopathy and 24 of 53 patients without. The lever arm ratio in the group with patellar tendinopathy versus controls was 1.71 versus 1.01 (P = .01), with a moment arm difference of 1.00 versus 0.80 (P < .01), respectively. There was no difference detected between groups for patellar tendon angle, patellar tendon pivot point angle, knee flexion angle, or incidence of patella alta. No correlation was found with our measurements and the Insall-Salvati ratio. Statistical analysis was also performed according to sex, and a statistically significant difference between groups was found for differences in lever arm ratio and moment arm.

Conclusion

The lever arm ratio and moment arm ratio from lateral radiographs were significantly different between patients with and without patellar tendinopathy. Further study is needed on the biomechanical implications of the pivot point and how altering it can affect stress within the patellar tendon, patellofemoral joint, and associated clinical outcomes.

Modifiable risk factors for patellar tendinopathy in athletes: a systematic review and meta-analysis

OBJECTIVE

To perform a systematic review and meta-analysis identifying (1) potential modifiable risk factors and (2) associated modifiable factors for patellar tendinopathy in athletes.

DESIGN

A systematic review and meta-analysis was conducted. Risk of bias was assessed using the Newcastle-Ottawa Scale and grouped based on study design. Meta-analytic statistics were performed for items reported by five or more studies. A strength of evidence rating is provided for items not appropriate for meta-analysis.

DATA SOURCES

PubMed, Web of Science, Scopus and Cinahl were searched on 14 November 2017.

ELIGIBILITY CRITERIA

Quantitative, original research reporting potential modifiable risk factors or associated factors, comparing athletes with patellar tendinopathy with a group without the injury.

RESULTS

862 records were screened and 31 articles were included (6 prospective, 25 cross-sectional). There was a lack of strong evidence for any potential modifiable risk factor or associated factors. There was limited or conflicting evidence that decreased ankle dorsiflexion range of motion, decreased posterior thigh and quadriceps flexibility, greater volume of jump training, more volleyball sets played per week, greater countermovement jump (CMJ) height and greater activity volume are potential modifiable risk factors. Meta-analysis supported greater activity volume (Cohen's d=0.22, 95% CI 0.06 to 0.39, p=0.008), higher body weight (0.36, 0.17 to 0.55, p<0.001) and greater CMJ height (0.31, 0.07 to 0.56, p=0.01) as associated modifiable factors.

CONCLUSIONS

There is a lack of strong evidence for any potential modifiable risk factors or associated factors. Factors with lower levels of support may be of interest in designing prevention programmes but require further research in high-quality, prospective studies.

Getting the most out of intensive longitudinal data: a methodological review of workload-injury studies

OBJECTIVES

To systematically identify and qualitatively review the statistical approaches used in prospective cohort studies of team sports that reported intensive longitudinal data (ILD) (>20 observations per athlete) and examined the relationship between athletic workloads and injuries. Since longitudinal research can be improved by aligning the (1) theoretical model, (2) temporal design and (3) statistical approach, we reviewed the statistical approaches used in these studies to evaluate how closely they aligned these three components.

DESIGN

Methodological review.

METHODS

After finding 6 systematic reviews and 1 consensus statement in our systematic search, we extracted 34 original prospective cohort studies of team sports that reported ILD (>20 observations per athlete) and examined the relationship between athletic workloads and injuries. Using Professor Linda Collins' three-part framework of aligning the theoretical model, temporal design and statistical approach, we qualitatively assessed how well the statistical approaches aligned with the intensive longitudinal nature of the data, and with the underlying theoretical model. Finally, we discussed the implications of each statistical approach and provide recommendations for future research.

RESULTS

Statistical methods such as correlations, t-tests and simple linear/logistic regression were commonly used. However, these methods did not adequately address the (1) themes of theoretical models underlying workloads and injury, nor the (2) temporal design challenges (ILD). Although time-to-event analyses (eg, Cox proportional hazards and frailty models) and multilevel modelling are better-suited for ILD, these were used in fewer than a 10% of the studies (n=3).

CONCLUSIONS

Rapidly accelerating availability of ILD is the norm in many fields of healthcare delivery and thus health research. These data present an opportunity to better address research questions, especially when appropriate statistical analyses are chosen.

Восстановление физической работоспособности юных волейболистов на этапе специализированной базовой подготовки с помощью применения средств фитнеса аэробной направленности

Целью работы являлось выявление влияния применения средств аэробной направленности на эффективность восстановления юношей и девушек, занимающихся волейболом. Материал и методы. В исследовании приняли участие спортсмены, занимающиеся волейболом в количестве 30 мальчиков и 30 девочек (в возрасте 16-17 лет). В течение девяти месяцев во время восстановительных микроциклов спортсмены занимались фитнесом с элементами аэробики с тренером по фитнесу. Перед проведением исследования были проанализированы медицинские карты всех испытуемых, содержащие наблюдения за спортсменами в течение 1 года. Анализ медицинских карт позволил сделать заключение, что в течение последнего года все сортсмены были здоровы, однако не наблюдалось улучшения процессов восстановления работоспособности. Поэтому было принято решение разработки и применения специальной методики восстановления и повышения работоспособности. Для этого была разработана методика повышения работоспособности и улучшения процессов восстановления с применением средств аэробики. Результаты. Выявлены достоверные различия по результатам тестов «Прыжки через скакалку в течение 1 мин» и «Подъем туловища из положения лежа в положение сидя в течение 30 с» до и после проведения эксперимента. После эксперимента количество потерь мяча в тесте с нападающим ударом было достоверно ниже по сравнению с данными до эксперимента. В результате применения фитнеса с элементами аэробики в тренировочном процессе волейболистов 16-17 лет уровень функциональных возможностей и показателей физической подготовленности спортсменов достоверно возрос. Выводы. Разработанная методика положительно влияет как на девочек, так и на мальчиков. Под влиянием разработанной методики улучшение процессов восстановления у девочек более выражено по сравнению с мальчиками.

Resting Hormone Alterations and Injuries: Block vs. DUP Weight-Training among D-1 Track and Field Athletes

Daily undulating periodization (DUP), using daily alterations in repetitions, has been advocated as a superior method of resistance training, while traditional forms of programming for periodization (Block) have been questioned. Nineteen Division I track and field athletes were assigned to either a 10-week Block or DUP training group. Year and event were controlled. Over the course of the study, there were four testing sessions, which were used to evaluate a variety of strength characteristics, including maximum isometric strength, rate of force development, and one repetition maximum (1RM). Although, performance trends favored the Block group for strength and rate of force development, no statistical differences were found between the two groups. However, different (p ≤ 0.05) estimated volumes of work (VL) and amounts of improvement per VL were found between groups. Based upon calculated training efficiency scores, these data indicate that a Block training model is more efficient in producing strength gains than a DUP model. Additionally, alterations in testosterone (T), cortisol (C) and the T:C ratio were measured. Although there were no statistically (p ≤ 0.05) different hormone alterations between groups, relationships between training variables and hormone concentrations including the T:C ratio, indicate that Block may be more efficacious in terms of fatigue management.

Injuries in Collegiate Women's Volleyball: A Four-Year Retrospective Analysis

A four-year retrospective analysis of injury data was conducted on a collegiate (NCAA Division I) women’s volleyball team. Twenty athletes (Year 1: age = 19.4 ± 0.9 y, height = 175.2 ± 5.1 cm, body mass = 70.5 ± 10.2 kg; Year 2: age = 20.1 ± 1.0 y, height = 175.7 ± 4.7 cm, body mass = 69.5 ± 10.1 kg; Year 3: age = 20.1 ± 1.4 y, height = 173.8 ± 6.3 cm, body mass = 69.9 ± 10.8 kg; Year 4: age = 19.5 ± 1.4 y, height = 174.4 ± 8.6 cm, body mass = 72.7 ± 10.8 kg) participated in this study, accounting for 1483 total training exposures. Injury was defined as any damage to a body part, incurred during volleyball or strength and conditioning-related activities, which interfered with training and/or competition. Injury rate was normalized to the number of athletes and exposure and expressed as injuries per 1000 exposures. A total of 133 injuries were recorded. The most common injury was to the knee (left = 7.5%, right = 12.0%). Injuries occurred most often in volleyball practice (75.2%), followed by competition (20.3%), and strength and conditioning-related activities (4.5%). Non-contact injuries (upper body = 26.3%, lower body = 53.4%) were more common than contact injuries (upper-body = 13.5%, lower-body = 6.8%). An examination of injury rates relative to the training year revealed patterns in injury occurrence. Specifically, spikes in injury rate were consistently observed during periods of increased training volume that were preceded by breaks in organized training, such as the early pre-season and off-season training periods.

Physical Activity Level and Sport Participation in Relation to Musculoskeletal Pain in a Population-Based Study of Adolescents: The Young-HUNT Study

Background:

Prevalence of musculoskeletal pain among adolescents is high, and pain in adolescence increases the risk of chronic pain in adulthood. Studies have shown conflicting evidence regarding associations between physical activity and musculoskeletal pain, and few have evaluated the potential impact of sport participation on musculoskeletal pain in adolescent population samples.

Purpose:

To examine the associations between physical activity level, sport participation, and musculoskeletal pain in the neck and shoulders, low back, and lower extremities in a population-based sample of adolescents.

Study Design:

Cross-sectional study; Level of evidence 4.

Methods:

Data from the Nord-Trøndelag Health Study (Young-HUNT3) were used. All 10,464 adolescents in the Nord-Trøndelag county of Norway were invited, of whom 74% participated. Participants were asked how often they had experienced pain, unrelated to any known disease or acute injury, in the neck and shoulders, low back, and lower extremities in the past 3 months. The associations between (1) physical activity level (low [reference], medium or high) or (2) sport participation (weekly compared with no/infrequent participation) and pain were evaluated using logistic regression analyses, stratified by sex, and adjusted for age, socioeconomic status, and psychological distress.

Results:

The analyses included 7596 adolescents (mean age, 15.8 years; SD, 1.7). Neck and shoulder pain was most prevalent (17%). A moderate level of physical activity was associated with reduced odds of neck and shoulder pain (OR = 0.79 [95% CI, 0.66-0.94]) and low back pain (OR = 0.75 [95% CI, 0.62-0.91]), whereas a high level of activity increased the odds of lower extremity pain (OR = 1.60 [95% CI, 1.29-1.99]). Participation in endurance sports was associated with lower odds of neck and shoulder pain (OR = 0.79 [95% CI, 0.68-0.92]) and low back pain (OR = 0.77 [95% CI, 0.65-0.92]), especially among girls. Participation in technical sports was associated with increased odds of low back pain, whereas team sports were associated with increased odds of lower extremity pain. Strength and extreme sports were related to pain in all regions.

Conclusion:

We found that a moderate physical activity level was associated with less neck and shoulder pain and low back pain, and that participation in endurance sports may be particularly beneficial. Our findings highlight the need for health care professionals to consider the types of sports adolescents participate in when evaluating their musculoskeletal pain.

At What Age Do Children and Adolescents Develop Lower Limb Tendon Pathology or Tendinopathy? A Systematic Review and Meta-analysis

BACKGROUND

Tendon pathology and tendinopathy have been reported in children and adolescents; however, the age at onset and prevalence of the conditions have not been examined systematically.

OBJECTIVE

To examine the prevalence of lower limb tendon pathology and tendinopathy in children and adolescents, and the factors associated with these conditions in this population.

METHODS

Six databases were searched (MEDLINE, the Cochrane Central Register of Controlled Trials, Embase, Scopus, the Web of Science and the Allied and Complementary Medicine Database). Studies were included if the prevalence of lower limb tendon pathology and/or tendinopathy were reported in humans under the age of 18 years. Studies were divided according to the method of diagnosis (physical examination, ultrasound or a questionnaire) and further divided into studies that reported prevalence data by tendon [reported two data points (right and left) for each participant] and those that reported prevalence data for each participant [reporting one data point (right or left) per participant].

RESULTS

Seventeen studies met the inclusion criteria. Lower limb tendinopathy prevalence (presence of pain and dysfunction) ranged between 8.2 and 33.3%, and increased in prevalence as age increased up to 18 years. The odds ratio for studies reporting tendinopathy by tendon was 0.37 (95% confidence interval 0.20-0.69) in favour of boys presenting with tendinopathy. Study aims and reporting methods were heterogeneous.

CONCLUSIONS

The age at onset of lower limb tendinopathy in children and adolescents has not been widely studied. This systematic review found that tendinopathy is present in children and adolescents, and increases in prevalence with age up to 18 years. Male sex is significantly associated with tendinopathy in studies that report tendinopathy by tendon.

Injuries and Associated Risk Factors Among Adolescent Elite Orienteerers: A 26-Week Prospective Registration Study

CONTEXT

In orienteering, the number of injury-registration studies is limited. Most researchers have used a cross-sectional design during specific events and, therefore, have mainly identified acute injuries.

OBJECTIVE

To determine the prevalence of injuries by registering acute and overuse injuries in adolescent elite orienteerers over 26 weeks and to study the variation of injury prevalence over the season and the potential risk factors.

DESIGN

Cohort study.

SETTING

Two high schools in Sweden with national orienteering teams.

PATIENTS OR OTHER PARTICIPANTS

All athletes (33 adolescent girls, 31 adolescent boys; age = 17 ± 1 years) from 2 high schools with orienteering teams.

MAIN OUTCOME MEASURE(S)

We used a weekly Web-based questionnaire to identify the incidence and prevalence of injuries and training variables. Risk factors for injury were calculated using multiple linear regression techniques.

RESULTS

The average weekly prevalence of overuse and acute injuries was 35.7% (95% confidence interval = 34.8%, 36.6%) and 1.7% (95% confidence interval = 1.3%, 2.1%), respectively; overuse injuries (78.0%, n = 85) accounted for the majority. The incidence of acute and overuse injuries was highest for the foot/lower leg (48.6%, n = 53), and 71.6% (n = 78) of all injuries affected the foot/lower leg and knee area. Time to the first reported injury was associated with training volume (β = 0.184, P = .001), competition time (β = -0.701, P = .009), running on asphalt roads (β = -0.348, P = .008), and running on forest surfaces and trails (β = -0.331, P = .007), with a model fit of r( 2) = 0.50 (intercept = 2.196, P < .001). During the study, we observed a weekly increase (0.3%) in the prevalence of overuse injuries in the foot/lower leg (r( 2) = 0.33, P = .001); the highest prevalence (26.9%) was at the beginning of the competitive season.

CONCLUSIONS

Overuse injuries, predominately in the foot/lower leg area, were more common than acute injuries in adolescent elite orienteerers. These injuries had the highest prevalence at the beginning of the competitive season; therefore, this period can be seen as a possible risk factor for sustaining overuse injuries in the foot/lower leg.

Injury risk is low among world-class volleyball players: 4-year data from the FIVB Injury Surveillance System

Background

Little is known about the rate and pattern of injuries in international volleyball competition.

Objective

To describe the risk and pattern of injuries among world-class players based on data from the The International Volleyball Federation (FIVB) Injury Surveillance System (ISS) (junior and senior, male and female).

Methods

The FIVB ISS is based on prospective registration of injuries by team medical staff during all major FIVB tournaments (World Championships, World Cup, World Grand Prix, World League, Olympic Games). This paper is based on 4-year data (September 2010 to November 2014) obtained through the FIVB ISS during 32 major FIVB events (23 senior and 9 junior).

Results

The incidence of time-loss injuries during match play was 3.8/1000 player hours (95% CI 3.0 to 4.5); this was greater for senior players than for junior players (relative risk: 2.04, 1.29 to 3.21), while there was no difference between males and females (1.04, 0.70 to 1.55). Across all age and sex groups, the ankle was the most commonly injured body part (25.9%), followed by the knee (15.2%), fingers/thumb (10.7%) and lower back (8.9%). Injury incidence was greater for centre players and lower for liberos than for other player functions; injury patterns also differed between player functions.

Conclusions

Volleyball is a very safe sport, even at the highest levels of play. Preventive measures should focus on acute ankle and finger sprains, and overuse injuries in the knee, lower back and shoulder.

Planning the International Competition Schedules for the Health of Elite Athletes: A 21-Year Retrospective Study Evaluating the Effectiveness and Economic Impact in an Olympic Sport

Background

The increased number of trips and competitions scheduled in the international agonistic calendars meets commercial demands while acting as a source of stress for the athletes. A model, developed in biathlons to monitor the so-called competition load, revealed an upward trend over time. The aim of this study was to evaluate, in a 21-year period, the effects of the International Biathlon Union’s rescheduling of the competitive calendars to control the competition load, as well as its stability over time and the economic impact of this intervention.

Methods

For each season competition, the load factors from the international agonistic calendar (number of venues/events, competition days/distance) were considered, and the athletes’ daily and maximal stress scores were calculated. The calendar rescheduling, which started in 2001, involved the length of competitions, number of resting days and frequency of travels. Data from the period pre (1994–2000) and post (2001–2007) the intervention, as well as follow-up (2008–2015), were compared and analyzed in relation to the federation’s budget.

Results

The competition load and athletes’ daily stress score progressively increased pre, plateaued post and remained stable in follow-up. Their annual variations within the final two periods were significantly lower than in the pre period, in spite of the higher average values. The maximal stress score decreased over time. The direct correlation between most of the competition load factors with the economic budget present in pre was lost in post and follow-up. Similarly, the athletes’ daily stress score had a stable trend in post and follow-up, while budget continued to increase.

Conclusions

The management of an athlete’s potential source of stress by an international federation stabilized the competition load over time, but it did not affect the budget. Furthermore, it uncoupled the relationship between the athlete’s effort and federation income.

Overuse injuries in youth basketball and floorball

Background

The popularity of team sports is growing among young people. High training volume and intensity may predispose young athletes to overuse injuries. Research to date has tended to focus on acute injuries rather than overuse injuries. The purpose of this study was to examine the occurrence, nature, and severity of overuse injuries in youth basketball and floorball, with the hypothesis that overuse injuries are frequent in youth team sports.

Methods

The study comprised a total of 401 Finnish team sports athletes (207 basketball and 194 floorball players). The data were collected using a detailed questionnaire. The participants (mean age 15.8±1.9 years) responded to the questionnaire covering information on overuse injuries during the previous 12 months.

Results

A total of 190 overuse injuries was reported (97 in basketball and 93 in floorball). In both sports, most of the injuries involved the lower extremities (66% and 55% of all injuries in basketball and floorball, respectively). In basketball, the most commonly injured site was the knee (44 cases, 45%). In floorball, the most commonly injured sites were the lower back/pelvis (36 cases, 39%) and knee (32 cases, 34%). Overuse injuries caused an average time loss from full participation of 26±50 (median 7) days in basketball and 16±37 (median 5) days in floorball.

Conclusion

Overuse injuries are a common problem in youth team sports, and often cause long-term absence from full participation. The findings suggest that injury reduction and training load monitoring strategies are needed in the field. More research using explicit prospective data collection is needed to better understand the problem.

Lower Extremity Kinematics During a Drop Jump in Individuals With Patellar Tendinopathy

Background:

Patellar tendinopathy (PT) is a common degenerative condition in physically active populations. Knowledge regarding the biomechanics of landing in populations with symptomatic PT is limited, but altered mechanics may play a role in the development or perpetuation of PT.

Purpose:

To identify whether study participants with PT exhibited different landing kinematics compared with healthy controls.

Study Design:

Controlled laboratory study.

Methods:

Sixty recreationally active participants took part in this study; 30 had current signs and symptoms of PT, including self-reported pain within the patellar tendon during loading activities for at least 3 months and ≤80 on the Victorian Institute of Sport Assessment Scale–Patella (VISA-P). Thirty healthy participants with no history of PT or other knee joint pathology were matched by sex, age, height, and weight. Participants completed 5 trials of a 40-cm, 2-legged drop jump followed immediately by a 50% maximum vertical jump. Dependent variables of interest included hip, knee, and ankle joint angles at initial ground contact, peak angles, and maximum angular displacements during the landing phase in 3 planes. Independent-samples t tests (P ≤ .05) were utilized to compare the joint angles and angular displacements between PT and control participants.

Results:

Individuals with PT displayed significantly decreased peak hip (PT, 59.2° ± 14.6°; control, 67.2° ± 13.9°; P = .03) and knee flexion angles (PT, 74.8° ± 13.2°; control, 82.5° ± 9.0°; P = .01) compared with control subjects. The PT group displayed decreased maximum angular displacement in the sagittal plane at the hip (PT, 49.3° ± 10.8°; control, 55.2° ± 11.4°; P = .04) and knee (PT, 71.6° ± 8.4°; control, 79.7° ± 8.3°; P < .001) compared with the control group.

Conclusion:

Participants with PT displayed decreased maximum flexion and angular displacement in the sagittal plane, at both the knee and the hip. The altered movement patterns in those with PT may be perpetuating symptoms associated with PT and could be due to the contributions of the rectus femoris during dynamic movement.

Clinical Relevance:

Based on kinematic alterations in symptomatic participants, rehabilitation efforts may benefit from focusing on both the knee and the hip to treat symptoms associated with PT.

Lipids, adiposity and tendinopathy: is there a mechanistic link? Critical review

Being overweight or obese is associated with an elevated risk of tendon pathology. However, for sportspeople the epidemiological data linking weight or adiposity on one hand, and risk of tendon pathology on the other, are less consistent. Indeed, the mechanistic links between diet, adiposity and tendon pathology remain largely unexamined. Recent studies have begun to examine the effects of dietary interventions on outcomes such as tendon biomechanics or pain. Oxidised low-density lipoprotein has been shown to (A) accumulate in the tendon tissues of mice that eat a fatty diet and (B) induce a pathological phenotype in human tendon cells. This paper addresses the current debate: is excessive body mass index (causing increased load and strain on tendon tissue) per se the underlying mechanism? Or do local or systemic influences of fat on tendons predispose to tendon pathology? This narrative review argues that excessive blood lipids may be an important avenue for clinical investigations.

The prevalence of patellar tendinopathy in elite academy rugby: a clinical and imaging study

OBJECTIVES

Patellar tendinopathy (PT) is a challenging condition with variable outcomes. It is not commonly reported in rugby. This study was undertaken to evaluate the prevalence of PT in elite academy rugby.

DESIGN

Cross-sectional study.

METHODS

Members of the rugby academies in Ireland were evaluated using blinded, standardised clinical examination, self reported questionnaires and ultrasound. Anthropometrics were examined, body mass and fat% were measured by bio-impedance. The Cincinnati Sports Activity Scale, established activity levels. The VISA-P scale evaluated symptoms. Ultrasound examination established tendon thickness, echogenicity and homogeneity including focal areas of tendinopathy in both transverse and longitudinal planes. Studies were reviewed and graded by two musculoskeletal radiologists. Statistical analysis was performed using PASW 18 and CIA software. Significance was set at p<.05.

RESULTS

Thirty individuals (36.1%) had US abnormalities identified with 38 abnormal tendons. The abnormalities seen were microcalculi (44.7%; N=17), thickened tendons ± large areas of cystic degenerative change (26.3%) and macrocalculi or large hypoechoic areas (28.9%; N=11). Eleven individuals (13.3%) fulfilled the clinical diagnosis of PT based on clinical examination. Combining both US and clinical the prevalence of PT in this cohort was 9.6% (N=8). There was a statistically significant difference between the prevalence of patellar tendinopathy based upon US findings (p=.027) and the combination of both clinical examination and US (p=.044) in different training academies.

CONCLUSIONS

This work shows that PT is a relatively common injury in elite academy rugby players and that training practices may contribute to its development.

Sports and exercise-related tendinopathies: a review of selected topical issues by participants of the second International Scientific Tendinopathy Symposium (ISTS) Vancouver 2012

In September 2010, the first International Scientific Tendinopathy Symposium (ISTS) was held in Umeå, Sweden, to establish a forum for original scientific and clinical insights in this growing field of clinical research and practice. The second ISTS was organised by the same group and held in Vancouver, Canada, in September 2012. This symposium was preceded by a round-table meeting in which the participants engaged in focused discussions, resulting in the following overview of tendinopathy clinical and research issues. This paper is a narrative review and summary developed during and after the second ISTS. The document is designed to highlight some key issues raised at ISTS 2012, and to integrate them into a shared conceptual framework. It should be considered an update and a signposting document rather than a comprehensive review. The document is developed for use by physiotherapists, physicians, athletic trainers, massage therapists and other health professionals as well as team coaches and strength/conditioning managers involved in care of sportspeople or workers with tendinopathy.