Association Between Spikes in External Training Load and Shoulder Injuries in Competitive Adolescent Tennis Players: The SMASH Cohort Study

A Risk Tool for Evaluating Overuse Injury and Return-to-Play Time Periods in Youth and Collegiate Athletes: Preliminary Study

BACKGROUND

Overuse injuries in youth athletes are associated with risks, including sports specialization, biological maturation, female sex, and workload measures. As no assessment tool exists to evaluate risk accumulation, we developed a novel risk factor scoring system (Sport Training Assessment of Risk [STAR]) to assess participants' risk of overuse injury and explore association with return-to-play (RTP) time periods.

HYPOTHESIS

(1) STAR will reach an acceptable predictive threshold in the assessment of overuse injury in youth athletes. (2) Higher STAR scores will be associated with increased RTP time periods after injury.

STUDY DESIGN

Longitudinal cohort study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Youth athletes with an injury sustained during competitive sport completed questionnaires. Association of questionnaire variables with injury risk type was evaluated via logistic regression analyses, and unweighted and weighted versions of a total risk score were developed. RTP was defined by physician clearance per electronic medical record review. Mantel-Haenszel chi-square tests and Kendall's rank correlation coefficients were used to assess the relationship between weighted total risk score and RTP time periods. The weighted STAR model was analyzed with receiver operating characteristic (ROC) curves.

RESULTS

The weighted STAR model trended toward an acceptable level of prediction for overuse (nonserious + serious) injury (area under the ROC curve [AUC], 0.66; 95% CI, 0.61-0.71), but was less predictive for serious overuse injury (AUC, 0.63; 95% CI, 0.55-0.71). Weighted total risk score was weakly associated with return to full play (ρ = 0.11; P < 0.01), and potentially with return to modified play (ρ = -0.08; P = 0.04).

CONCLUSION

STAR may be a feasible tool for assessing overuse injury risk and RTP time periods in youth athletes but requires further development, as it did not reach an acceptable predictive threshold in this preliminary study.

CLINICAL RELEVANCE

Clinicians can use STAR to assess overuse injury risk in youth athletes.

Risk Factors for Injury in Border Collies Competing in Agility Competitions

Border Collies are the most common breed in agility and their reported injury rate is much higher than that of other breeds. We aimed to identify demographic, training, and competition variables associated with the injury risk for this breed. We hypothesized that higher jump heights and competition at national/international levels would increase the injury risk. Data were collected from an internet-based survey. A logistic regression model was built using backward selection. There were 934 Border Collies in the sample, with 488 reporting an injury. The jump height relative to the shoulder height was associated with injury, with dogs jumping noticeably above or below shoulder height more likely to report a history of injury. Other identified risk factors included the number of weekends spent competing/year, the number of competitions at the national level, the age when starting elbow height jumps and backside jumps, the acquisition of the dog from a breeder, and the age of the handler. Factors associated with prolonged injury (>3-month duration) were the age when starting elbow height jumps and having a veterinary assistant as a handler. Border Collies jumping above shoulder height had an increased risk of injury. However, those jumping below shoulder height were also at a higher risk, which could have been due to reverse causality. Similarly, the observed associations regarding differences based on the number of trial weekends/year may have been impacted by reverse causality as well. The increased risk of injury with elbow height jump training at <10 months of age may indicate that the repetitive impact of jump training prior to skeletal maturity negatively influences musculoskeletal development. These data provide valuable information for further prospective studies.

Lower-Extremity Injuries Predominate in American High School Tennis Players

Purpose

To describe injury epidemiology in U.S. adolescent tennis players between 2014 and 2018 via the High School Reporting Information Online (HS RIO) database.

Methods

The HS RIO database was queried for injury data on high school tennis players as reported by athletic trainers between 2014 and 2018. Injuries were analyzed according to athlete demographics, injury type, location, and context. Variables of interest between male and female athletes were compared using Pearson χ2 test or Fisher exact test.

Results

In total, 176 injuries in high school tennis players between 2014 and 2018 were identified in the HS RIO database. Overall, 25.6% (45/176) occurred in the ankle, 12.5% (22/176) in the knee, and 9.7% (17/176) in the wrist. The most common types of injuries were ligament sprains and muscle strains at 35.2% (62/176) and 17.6% (31/176) of injuries, respectively. Although most injuries were unrelated to contact, such as overuse and heat exertion or stroke, 28.7% (47/176) of injuries were the result of rotation around a planted foot/inversion of the foot. We found no difference in injury patterns between male and female high school tennis athletes.

Conclusions

We found no difference in injury patterns between male and female U.S. high school tennis athletes. The ankles, knees, and wrists were the most commonly injured areas in this population. The most common types of injuries were ligament sprains and muscle strains. Although many injuries were new, athletes rarely required surgery and returned to play. Finally, we found no difference in injury patterns between male and female high school tennis athletes.

Clinical Relevance

The epidemiology of injuries among high school tennis players is poorly understood. The information from this study will help us to understand these injuries and how we may be able to better prevent them.

The Fine-Tuning Approach for Training Monitoring

PURPOSE

Monitoring is a fundamental part of the training process to guarantee that the programmed training loads are executed by athletes and result in the intended adaptations and enhanced performance. A number of monitoring tools have emerged during the last century in sport. These tools capture different facets (eg, psychophysiological, physical, biomechanical) of acute training bouts and chronic adaptations while presenting specific advantages and limitations. Therefore, there is a need to identify what tools are more efficient in each sport context for better monitoring of training process.

METHODS AND RESULTS

We present and discuss the fine-tuning approach for training monitoring, which consists of identifying and combining the best monitoring tools with experts' knowledge in different sport settings, designed to improve (1) the control of actual training loads and (2) understanding of athletes' training adaptations. Instead of using single-tool approaches or merely subjective decision making, the identification of the best combination of monitoring tools to assist experts' decisions in each specific context (ie, triangulation) is necessary to better understand the link between acute and chronic adaptations and their impact on health and performance. Future studies should elaborate on the identification of the best combination of monitoring tools for each specific sport setting.

CONCLUSION

The fine-tuning monitoring approach requires the simultaneous use of several valid and practical tools, instead of a single tool, to improve the effectiveness of monitoring practices when added to experts' knowledge.

Methods of Monitoring Internal and External Loads and Their Relationships with Physical Qualities, Injury, or Illness in Adolescent Athletes: A Systematic Review and Best-Evidence Synthesis

BACKGROUND

With the increasing professionalisation of youth sports, training load monitoring is increasingly common in adolescent athletes. However, the research examining the relationship between training load and changes in physical qualities, injury, or illness in adolescent athletes is yet to be synthesised in a systematic review.

OBJECTIVE

The aim of this review was to systematically examine the research assessing internal and external methods of monitoring training load and physical qualities, injury, or illness in adolescent athletes.

METHODS

Systematic searches of SPORTDiscus, Web of Science, CINAHL and SCOPUS were undertaken from the earliest possible records to March 2022. Search terms included synonyms relevant to adolescents, athletes, physical qualities, injury, or illness. To be eligible for inclusion, articles were required to (1) be original research articles; (2) be published in a peer-reviewed journal; (3) include participants aged between 10 and 19 years and participating in competitive sport; (4) report a statistical relationship between a measure of internal and/or external load and physical qualities, injury or illness. Articles were screened and assessed for methodological quality. A best-evidence synthesis was conducted to identify trends in the relationships reported.

RESULTS

The electronic search yielded 4125 articles. Following screening and a review of references, 59 articles were included. The most commonly reported load monitoring tools were session ratings of perceived exertion (n = 29) and training duration (n = 22). Results of the best-evidence synthesis identified moderate evidence of positive relationships between resistance training volume load and improvement in strength, and between throw count and injury. However, evidence for other relationships between training load and change in physical qualities, injury, or illness were limited or inconsistent.

CONCLUSIONS

Practitioners should consider monitoring resistance training volume load for strength training. Additionally, where appropriate, monitoring throw counts may be useful in identifying injury risk. However, given the lack of clear relationships between singular measures of training load with physical qualities, injury, or illness, researchers should consider multivariate methods of analysing training load, as well as factors that may mediate the load-response relationship, such as maturation.

CORRELATION BETWEEN LOCATION AND CAUSE OF INJURIES IN TENNIS PLAYERS

ABSTRACT Introduction Tennis is a network sport that requires strength, endurance, agility, speed, skill, and other physical demands from participants. Tennis athletes are subject to injuries in their daily training, affecting their competitive performance. Objective Explore the correlation between the location of injuries and the cause of injuries in tennis players. Methods Tennis players were selected as the research subjects. In this study, a questionnaire was used to record tennis injuries. The rehabilitation treatment of tennis players after injuries was summarized and analyzed through statistical methods. Results The main forms of serious sports injuries caused by tennis players were acute and moderate injuries. The most common fractures are mainly ligament and tendon: joint ligament injury or tear, muscle ligament injury, bursitis, and soft tissue ligament contusion. The joints most commonly involved are knees, ankles, elbows, wrists, and shoulders. Conclusion The common causes of sports injuries in tennis players are the inaccuracy of technical movements, insufficient muscular strength, and insufficient strength for preparatory technical activities. In practice, it is recommended that athletes correct and standardize their movements. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Athletic Identity and Shoulder Overuse Injury in Competitive Adolescent Tennis Players: The Smash Cohort Study

Objectives

Our primary aim was to determine if athletic identity is prospectively associated with shoulder overuse injuries. Secondly, we aimed to determine if athletic identity is prospectively associated with playing through pain and to describe how athletic identity relates to sex, age, playing level, weekly training load, and match volume.

Methods

A cohort of 269 adolescent tennis players were followed over a period of 52 weeks. Cox regression was used to estimate the hazard rate ratio (HRR) of first-time shoulder overuse injury associated with every 10-unit increase on the Athletic Identity Measurement Scale (AIMS).

Results

The adjusted HRR of shoulder overuse injury was 0.89 (95% CI: 0.36–2.20) and the odds ratio of playing through pain was 2.41 (95% CI: 0.74–8.96) for every 10 unit increase on AIMS. The level of athletic identity was higher among players at the national level than among players at the regional level and was weakly correlated to weekly hours of tennis matches, tennis training, and fitness training.

Conclusions

Our results indicate that higher levels of athletic identity may be associated with a lower incidence of shoulder overuse injuries, and potentially with playing through pain, although these results are inconclusive due to wide confidence intervals.

Force-Time Curve Variable Outcomes Following a Simulated Tennis Match in Junior Players

This study examined the alterations induced by a simulated tennis competition on maximal isometric voluntary contraction (MVC), peak rate of force development (PRFD) and rate of force development (RFD) at different stages of contraction. Twenty junior tennis players performed an 80-minute simulated tennis match and two (pre and post) muscular performance tests. Variables tested included MVC, PRFD and RFD at 50, 100, 150 and 200 ms while performing a 90º shoulder internal rotation (IR90), 90º shoulder external rotation (ER90), shoulder horizontal adduction (ADD), shoulder horizontal abduction (ABD) and isometric mid-thigh pull (IMTP). Serve velocity (SV) was also registered. No significant changes were found regarding MVC, PRFD or SV. Non-significant moderate effect size (ES) towards a decrease in the IR90 RFD at 50 ms could be observed (16%; ES = 0.5) alongside an increase in the ADD and IMTP RFD at 150 ms (-15.8%, -8.2%; ES = -0.53, -0.54) and IMTP RFD at 200 ms (-13%; ES = -0.54). Results indicate that MVC, PRFD, RFD at different time intervals and SV are unaltered following an 80-minute simulated match, possibly due to insufficient alterations triggered on key factors affecting the tested variables.

Effect of Fatiguing Wheelchair Propulsion and Weight Relief Lifts on Subacromial Space in Wheelchair Users

Objective

This study aimed to identify targets of intervention for reducing shoulder pain in wheelchair users with spinal cord injury (SCI) by (1) examining changes in subacromial space [acromiohumeral distance (AHD) and occupation ratio (OccRatio)] with fatiguing wheelchair propulsion, and different loading conditions [unloaded position vs. weight relief lifts (WRL)]; (2) associating these changes with wheelchair user capacity, as well as (3) identifying subject characteristics associated with subacromial space, such as sex, lesion level, time since injury, body mass index and impaired shoulder range of motion.

Methods

Fifty manual wheelchair users with SCI [11 females, age = 50.5 (9.7) years, time since injury = 26.2 (11.4) years] participated in this quasi-experimental one-group pretest-posttest study. Ultrasound images were used to define AHD during an unloaded position, and during personal and instructed WRL before and after fatiguing wheelchair propulsion. Furthermore, supraspinatus and biceps thickness defined from ultrasound images were used to calculate OccRatios. Wheelchair user capacity was quantified as functional strength (maximum resultant force reached during maximum isometric forward push) and anaerobic work capacity (highest power output reached during 15-m sprint test). Multilevel mixed-effects linear regression analyses controlling for between subject variability and covariables were performed to address the research questions.

Results

AHD was significantly smaller during personal WRL (p &lt; 0.001) and instructed WRL (p = 0.009, AHD both 11.5 mm) compared to the unloaded position (11.9 mm). A higher wheelchair user capacity (higher anaerobic work capacity) reduced the impact of WRL on AHD decrease. The fatiguing wheelchair propulsion had no effect on AHD (p = 0.570) and on OccRatio of supraspinatus (p = 0.404) and biceps (p = 0.448). Subject characteristics related to a larger subacromial space were lower lesion level, shorter time since injury, impaired external rotation, a lower body mass index and a higher anaerobic work capacity.

Conclusion

This study showed a significant reduction in AHD during WRL with no effect of fatiguing wheelchair propulsion on the subacromial space in wheelchair users with SCI. A higher anaerobic work capacity was beneficial in stabilizing the shoulder during WRL. Our findings may assist clinicians in designing a shoulder injury prevention program.

Multicomponent stretching and rubber band strengthening exercises do not reduce overuse shoulder injuries: a cluster randomised controlled trial with 579 handball athletes

Objectives

Handball is associated with a high risk of overuse shoulder injury. This study investigated if an injury prevention programme effectively reduces overuse injury to the throwing shoulder of handball athletes.

Methods

61 men’s and women’s handball teams (u-19 and senior athletes) were cluster-randomised into an intervention and a control group in the 2019–2020 season. Players of the intervention group regularly carried out an injury prevention programme. Both groups documented overuse shoulder injuries via an online questionnaire every second week. The primary endpoint was the prevalence of overuse injury to the throwing shoulder. Secondary endpoints were the influence of compliance on the primary endpoint and intensity of overuse shoulder symptoms measured by a shortened, handball-specific Western Ontario Shoulder Index (WOSI).

Results

31 teams (295 players) in the intervention group and 30 teams (284 players) in the control group were included for analyses. The overall questionnaire response rate was 61%. The average prevalence of overuse shoulder injury did not significantly differ between the intervention group (n=109, 38.4% (95% CI 32.9% to 44.2%)) and the control group (n=106, 35.9% (95% CI 30.7% to 41.6%), p=0.542). Compliance with the intervention programme did not significantly affect overuse shoulder injury (p=0.893). Using generalised estimating equations for WOSI, the estimated mean for the intervention group was 44.6 points (95% CI 42.0 to 47.1) and 47.6 points for the control group (95% CI 44.9 to 50.3, p=0.111).

Conclusions

A multicomponent exercise programme using rubber bands and stretching did not significantly reduce the prevalence or symptoms of overuse throwing shoulder injury in handball athletes of both sexes. Randomised controlled study; level of evidence I.

Trial registration number

ISRCTN99023492.