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Letter
Time to bin the term ‘overuse’ injury: is ‘training load error’ a more accurate term?
  1. M K Drew1,2,3,
  2. C Purdam1,2,3
  1. 1 Department of Physical Therapies, Australian Institute of Sport, Canberra, Australian Capital Territory, Australia
  2. 2 Australian Centre for Research into Injury in Sport and its Prevention (ACRISP), Federation University Australia, Ballarat, Victoria, Australia
  3. 3 Department of Physiotherapy, University of Canberra, Canberra, Australian Capital Territory, Australia
  1. Correspondence to MK Drew, Department of Physical Therapies, Australian Institute of Sport, Australian Sports Commission, Canberra, VIC 2617, Australia; Mick.Drew{at}ausport.gov.au

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We read the recent systematic review on the prevalence, incidence and risk factors for overuse injuries of the wrist in young athletes and agree with the conclusion that age and early specialisation (early training commencement) are risk factors for injury.1 The study highlighted training intensity as a risk factor for overuse injuries. Given changes in training loads precede the onset of injury in cricket,2 football (soccer)3 and Australian football,4 we consider that overuse injuries can be considered errors in training load prescription and labelled as such. Care should also be taken with broadly labelling training intensity as a risk factor as moderate training loads are protective against injury Gabbett's ‘training injury prevention paradox’.5 ,6 High training loads may predispose to injury in some tissues more than others;2 they can protect against injury when coupled with small magnitude changes in training loads.6

We have included a case study of an athlete diagnosed with intersection syndrome (twice) to illustrate this definitional issue of ‘overuse’ injury in the wrist. Figure 1 below shows daily ‘internal’ training loads (RPE × minutes, ‘exertional minutes’) and acute:chronic workload ratio7 recorded by the athlete across a 65-day period in which two wrist injuries occurred. While on face value it appears that overuse, that is, a higher than average load was the major precursor, note the periods of low relative training load preceding the injury. These may represent a period of tissue deconditioning. Figure 2 highlights that the wrist injuries occurred in a low training load period relative to other periods throughout the year. Should the definition of overuse injuries be recast to also consider the underuse component of the patient loading history?

Figure 1

Acute:chronic workload ratio of ‘internal’ training loads (where ‘internal training load’ represents the minutes trained multiplied by the self-reported rating of perceived exertion (RPE) for that training session). To calculate acute:chronic load ratio, the acute workload (most recent 1 week internal training load) is divided by the chronic, workload (weekly average internal training load calculated from a frame of the past 4 weeks). An acute:chronic workload ratio >1.5 is a risk factor for injury; internal training load, the product of the rate of perceived exertion and duration (minutes); Note: Sport and training units have been de-identified to protect the anonymity of the athlete. Red bars represent the day of injury occurrence. The horizontal bars are equal.

Figure 2

Daily internal training loads over a 365-day period. The yearly data is presented for the same athlete. The time period in figure 1 is highlighted by the orange box with the injury days shown in red. Daily training was much lower in the month preceding injury (days 30–0). Note that the overall injury period had a much lower daily volume than the non-injured period (day 77 onwards). The horizontal bars are equal in both figures.

In this example the training environment has not been conducive in preparing the tissue for the demands of the sport. The important clinical relevance of this is that labelling these injuries as ‘overuse’ may encourage athletes to reduce their training unduly, thus exposing their tissues to deconditioning3 or an inconsistent loading pattern2 which have been associated with injuries. The implications for clinicians are that subjective examination should explore not only supranormal training load but also periods of low/no load and the trajectory from this to injury presentation. Gabbett has written that ‘high training workloads alone do not cause sports injuries: how you get there is the real issue’;8 and our case may illustrate the same. We call for our field to avoid the term ‘overuse’ injury and replace it with ‘training load error’ injury.

References

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Footnotes

  • Twitter Follow Michael Drew at @_mickdrew

  • Competing interests None declared.

  • Patient consent Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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