Background Training volume has been shown to influence injury risk in elite Rugby Union players.

Objective To investigate the influence of training volume on injury risk in elite Scottish Rugby Union players.

Design A prospective, observational cohort study design was adopted to collect training volume (hours) and injury data (training and match time-loss injuries combined).

Setting Data were collected from Scottish Rugby Union’s professional (Men’s 15-a-side) teams (Men’s International Squad; Glasgow Warriors and Edinburgh Rugby).

Patients (or Participants) Data were collected from 163 professional Rugby Union players over the 2017/18 and 2018/19 seasons.

Interventions (or Assessment of Risk Factors) Gym & pitch-based training data were collected via team logs & Global Positioning System devices. Injury data were collected from the medical personnel associated with each team.

Main Outcome Measurements Derived workload measures were calculated. These included: the exponentially-weighted moving average acute: chronic workload ratio (ACWR); week-to-week change in volume, and 1- 2-, 3- and 4-week cumulative volumes. Workload measures were modelled against subsequent week injury using binary logistic regression analysis. Odds ratios (OR) were reported against a reference (‘Very-low’ workload) group.

Results Players spent a total of 58,044 hours training, and sustained 734 time-loss injuries. Compared to the reference category (<0.50), an ‘Intermediate-low’ ACWR (0.75–1.00) had the lowest injury risk (OR=0.46). Contrary, an ‘Intermediate-high’ (1.00–1.25), ‘High’ (1.25–1.50) and ‘Very-high’ (>1.50) ACWR significantly increased injury risk (OR=4.85, 13.36 and 15.70, p<0.001, respectively). Injury risk was significantly increased for ‘Intermediate-low’ training volumes over 1–3 week cumulative periods, and ‘Intermediate-high’ volumes over 2–4 week cumulative periods. ‘Very-high’ volumes increased injury risk over 1–3 week cumulative periods. ‘High’ training volumes over 1–4 weeks and weekly change in volume were not associated with injury (p>0.05).

Conclusions Increases in acute training volume beyond a player’s current chronic status may increase injury risk. Minimising spikes in volume, whilst gradually acquiring high training volumes may be more protective against injury than intermediate and very high volumes.