This study addresses the challenge of accurately estimating Elevation Gain (EG) in trail running using GPS devices, where resolution of Digital Elevation Models (DEMs) plays a critical role. We propose an algorithmic enhancement to increase the resolution of a 4m DEM to 20cm, aligning it closely with high-resolution LiDAR models. Quantitative analyses reveal that this method significantly improves EG estimations, demonstrating a considerable reduction in error margins compared to conventional EG estimation using raw GPS. Specifically, our findings indicate that the bilinearly interpolated DEM achieves near-LiDAR accuracy at 20cm resolution, with error rates markedly decreasing at this scale. This study underscores the potential of using enhanced-resolution DEMs as a cost-effective alternative to LiDAR, particularly in applications like trail running where precise elevation data is crucial. Our approach not only offers a substantial improvement in the accuracy of physical workload assessments but also enhances the accessibility of high-quality elevation data for broader geographical and environmental applications.