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081 Spikes in external training load are associated with shoulder injuries in competitive adolescent tennis players – the SMASH cohort study
  1. Fredrik Johansson1,2,3,
  2. Ann Cools4,
  3. Jaime Fernandez-Fernandez5,
  4. Tim Gabbett6,7,
  5. Eva Skillgate1,2,3
  1. 1Musculoskeletal and Sports Injury Epidemiology Center, Sophiahemmet University, Stockholm, Sweden
  2. 2Intervention and Implementation research for worker health, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
  3. 3Naprapathögskolan – Scandinavian College of Naprapathic Manual Medicine, Stockholm, Sweden
  4. 4Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, Ghent University Hospital, Ghent, Belgium
  5. 5Department of Physical Activity and Sports Sciences, Universidad de León, León, Spain
  6. 6Gabbett Performance Solutions, Brisbane, Australia
  7. 7Centre for Health Research, University of Southern Queensland, Ipswich, Australia


Background Few studies have examined the association between the acute:chronic workload ratio (ACWR) and complaints/injuries in young tennis players. Primary aims: to investigate if accumulated external workload ‘spikes’ in ACWR of tennis training, match-play and fitness training, and if high or low workload/age ratio, were associated with the rate of shoulder complaints/injuries in competitive adolescent tennis players. Additional aims: to report the incidence of complaints/injuries stratified by sex and level of play, and describe shoulder injury characteristics.

Hypothesis Rapid increases in external workload are associated with the incidence of shoulder complaints and injuries.

Study design Cohort study.

Level of evidence 3

Methods At baseline 301 adolescent competitive tennis players, 13–19 years, were screened and followed weekly for 52 weeks with questionnaires, in years 2018–2019.

Information about time varying accumulated external workload spikes (uncoupled ACWR >1.3), and workload/age ratio, in 252 uninjured players were used in Cox regression analyses with the outcomes shoulder complaints (≥20) and injuries (≥40) (Oslo Sports Trauma Research Center Overuse Injury Questionnaire).

Results For each additional workload spike in tennis training/match-play the Hazard Rate Ratio (HRR) was 1.26 (95% CI: 1.13 – 1.40) for a shoulder complaint, and 1.26 (95% CI: 1.15 – 1.39) for a shoulder injury. The HRR for fitness training was 1.11 (95% CI: 1.02 – 1.20) for a shoulder complaint, and 1.18 (95% CI: 1.09 – 1.27) for a shoulder injury. Workload/age ratio was not associated to the rate of shoulder complaints or injuries.

Conclusion Accumulated external workload spikes of tennis training, match-play and/or fitness training are associated with a higher rate of shoulder complaints and shoulder injuries in competitive adolescent tennis players.

Clinical relevance Consistency in training load on a weekly basis is most likely more beneficial for adolescent tennis players regarding shoulder complaints/injuries than a training schedule comprising rapid increases (i.e. spikes) in workload.

  • workload
  • ACWR
  • tennis
  • adolescent
  • shoulder
  • injury

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