Photoplethysmographic imaging (PPG) is currently used to measure heart rate (HR) and the accuracy of PPG can be influenced by pigmentation of the skin; however, the effects of skin color-related artifacts on PPG during exercise remain unclear. This study aimed to assess the agreement between the Apple Watch photoplethysmography sensor and a criterion, for measuring heart rate across a range of intensities during exercise and to determine the influence of skin type on the accuracy of the measure. Forty-five males (20–43 y) completed the Fitzpatrick Skin Scale and were classified into three different skin type groups: a) types II (n = 15), III (n = 15) and IV (n = 15). Participants performed a graded incremental cycle-ergometer test while simultaneously wearing the Apple Watch and a Polar monitor as a criterion measure. Data from both devices were collected in 5-s epochs. Correlations between devices were very good (0.96–0.99 [95%CI: 0.94 to 0.99]). Significant differences were observed between skin types II and III when the intensity of the exercise was increased, albeit with trivial to small effect sizes (ES: 0.05 to 0.28). All significant differences corresponded t
