The objective of the investigation was to observe the impact of player wellbeing on the training output of elite soccer players.Prospective cohort design.Forty-eight soccer players (age: 25.3±3.1years; height: 183±7cm; mass: 72±7kg) were involved in this single season observational study across two teams. Each morning, pre-training, players completed customised perceived wellbeing questionnaires. Global positioning technology devices were used to measure external load (total distance, total high-speed running distance, high speed running, player load, player load slow, maximal velocity, maximal velocity exposures). Players reported ratings of perceived exertion using the modified Borg CR-10 scale. Integrated training load ratios were also analysed for total distance:RPE, total high speed distance:RPE player load:RPE and player load slow:RPE respectively.Mixed-effect linear models revealed significant effects of wellbeing Z-score on external and integrated training load measures. A wellbeing Z-score of −1 corresponded to a −18±2m (−3.5±1.1%), 4±1m (−4.9±2.1%,) 0.9±0.1kmh−1 (−3.1±2.1%), 1±1 (−4.6±2.9%), 25±3AU (−4.9±3.1%) and 11±0.5AU (−8.9±2.9%) reduction in total high speed distance, high speed distance, maximal velocity, maximal velocity exposures, player load and player load slow respectively. A reduction in wellbeing impacted external:internal training load ratios and resulted in −0.49±0.12mmin−1, −1.20±0.08mmin−1,−0.02±0.01AUmin−1 in total distance:RPE, total high speed distance:RPE and player load slow:RPE respectively.The results suggest that systematic monitoring of player wellbeing within soccer cohorts can provide coaches with information about the training output that can be expected from individual players during a training session.