## 2 Materials and Methods
### Data Collection  
The data collection system and procedures have been previously outlined in [PERSON] et al. (2018). Athletes self-reported through the online Kitman Labs(tm) ([[https://www.kitmanlabs.com/](https://www.kitmanlabs.com/)]([https://www.kitmanlabs.com/](https://www.kitmanlabs.com/))) application, accessed through a mobile phone. Athletes rated their perceived effort for the entirety of a session on the modified Borg scale (1-10) (adapted Borg CR10 scale (2019)) on the same day of completion. Athletes recorded the session duration (minutes) and activity type (i.e., swimming, S&C (Strength and Conditioning)--strength, S&C--conditioning or racing). sRPE-TL was calculated by multiplying the sRPE by the duration (20; 21; 22). Athlete training load data were accumulated and reported as weekly training load data and included the key variables as described in Table 2. Athlete data were audited for completeness weekly. MDCs (chartered physiotherapists) input injury data into a bespoke Microsoft Excel worksheet, designed in line with the Orchard Sports Injury and Illness Classification System (OSMICS) (2018). MDCs were emailed fortnightly reminders to input injury information. A monthly follow-up video call to audit the data was also conducted. Injury was subcat-egorised as medical attention, time loss or non-time loss. Time loss was reported from the date of onset until the athlete was fully available for training or competition. 'Fully \begin{table}
\begin{tabular}{l c c} \hline \hline
**Variable** & **Male** & **Female** \\ \hline N & 22 & 10 \\ Age (y) & 22 \(\pm\) 4 & 18 \(\pm\) 3 \\ Height (m) & 1.87 \(\pm\) 0.08 & 1.69 \(\pm\) 0.07 \\ Body Mass (kg) & 82.7 \(\pm\) 6.8 & 61.2 \(\pm\) 7.4 \\ Tier 5—World Class & 1 & 1 \\ Tier 4—Elite/International & 9 & 2 \\ Tier 3—Highly & 12 & 7 \\ Trained/National & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Athlete demographics. \begin{table}
\begin{tabular}{l c c} \hline \hline
**Training Load Metric** & **Calculation** & **Description** & **Scaled Units** \\ \hline Weekly Pool Volume (km) & All session volumes (km) from Monday to Sunday are summed together to generate weekly volume. & Distance swam per week \\
4-week Rolling Pool & Sum of the weekly volume for the current week and the & in kilometres & 1.0 km \\ Volume (km) & previous three weeks. & & swam for 4 weeks. \\ Weekly Pool Training & Session RPE * Duration (minutes) = sRPE-TL. Total pool & Pool training load for \\ Load (AU) & session sRPE-TL from Monday to Sunday summed & one week. & 100.0 AU \\ Weekly Gym Training & Session RPE * Duration (minutes) = sRPE-TL. Total & Gym training load for \\ Load (AU) & dryland session sRPE-TL from Monday to Sunday & one week. & 100.0 AU \\ Weekly Total Load & weekly pool and weekly gym values are summed together. & All training load for the \\ Training (AU) & together. & week. & 100.0 AU \\
4-week Rolling Total & Sum of the weekly total for the current week and the & Accumulated training \\ Training Load (AU) & previous three weeks. & load for 4 weeks. & 100.0 AU \\ \multicolumn{2}{c}{\(EWMA_{this\ week}=}\) & \\ \multicolumn{2}{c}{\(Load_{this\ week}\) * \(A_{a}+((1-A_{a})*EWMA_{last\ week})\),} & \\ \multicolumn{2}{c}{where \(\lambda_{a}\) is a value between 0 and 1 that represents the degree of decay, with higher values discounting older & The ratio of the acute \\ Acute: Chronic Workload & ob-servations at a faster rate. The \(\lambda_{a}\) is given by: & training load (past 7 \\ Ratio (ACWR) & \(\lambda_{a}=2/(N+1)\) & days) in relation to the \\ \multicolumn{2}{c}{\(\lambda_{a}=2/(N+1)\)} & chronic training load \\ \multicolumn{2}{c}{where \(N\) is the chosen time decay constant, typically 7} & (past 28 days). & \\ \multicolumn{2}{c}{and 28 days for acute (‘fatigue’) and chronic (‘fitiness’)} & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Description of the calculation of training load metrics.