Heart rate variability (HRV) is a popular and accessible monitoring tool utilized ubiquitously in the field to measure autonomic nervous system activity, readiness to train, and training adaptations. Acquisition of this information is essential for coaches, practitioners and athletes in order to effectively monitor positive training adaptations, nonfunctional over-reaching, injury and illness risk. However, longitudinal data assessing HRV changes with respect to training load in elite football is lacking. PURPOSE: To investigate changes in HRV and training load across several weekly training blocks in elite football. METHODS: Six male professional footballers (three defenders, three midfielders) from an English Premier League squad agreed to participate in this study. HRV was assessed with the ithlete application (HRV Fit Ltd, UK) using an Apple iPad2 (Apple Inc, CA), and a Polar T31 heart rate monitor (Polar Electro Ltd, Finland). HRV was calculated for each participant prior to the daily training session. Physical training load was monitored using a Global Positioning System (GPS) to quantify total distance (TD), high speed distance (HSD), training load (TL), impacts, maximum speed (MS), accelerations and decelerations, and energy expenditure (EE). Training sessions were separated into five equal training blocks (weeks 1 - 3, weeks 4 - 6, weeks 7 - 9, weeks 10 - 12 and weeks 13 - 15). RESULTS: There was a significant decrease in TD, HSD, TL, impacts and EE and a significant increase in MS, accelerations and decelerations across the five training blocks (p ≤ 0.03). However, there was no significant change in HRV (p = 0.27). CONCLUSION: The significant change in TL across the 15 week training period, despite no change in HRV may be due to the heterogeneity that exists in elite football players, where some athletes show smaller reductions in HRV in response to training compared to others. Subsequently it is important that individual changes in HRV are interpreted alongside additional monitoring methods (e.g. wellness, training load) to ensure that quantification of training adaptation, readiness to train and overreaching is accurate.