Golf is generally perceived as a safe and moderate sport; however, in middle-aged and older adults, it can pose significant health risks, including sudden cardiac events. Particularly during putting on the green, repetitive squatting and standing motions combined with psychological pressure may increase the risk of stroke or other cardiovascular incidents. In this pilot study, we aimed to investigate whether biometric signals can capture mental tension during golf play. Four healthy male participants were monitored while playing a full round of golf. We used a Holter ECG and a wearable pulse wave sensor to collect physiological data, including three-axis acceleration, R–R intervals (RRI), and heart rate variability (HRV) indices such as SDNN, LF, HF, and LF/HF ratio. Our analysis revealed no clear correlation between composite acceleration and RRI during the play. However, SDNN, LF, and HF values showed a tendency to increase by the final hole compared to the first hole, suggesting progressive autonomic adaptation or accumulated tension. Moreover, the LF/HF ratio decreased after play in all participants, indicating a shift toward parasympathetic dominance and a relaxation trend. These findings suggest that biometric signals, especially HRV indices, may reflect mental and physical changes during golf, potentially providing useful indicators for monitoring cardiovascular strain and risk in older adults engaged in this activity.