On the same track where history was made in 1954 when Sir Roger Bannister broke four minutes for the mile, our athletes tackled a workout that was once among Bannister's favorites: 10 x 400m at 1500m pace with a rolling 400m recovery. In the months building up to that historic day, Bannister would run this workout multiple times, gradually cutting down each lap until he ran 59 seconds for the final reps. As part of our spring season focussing on the track, we asked London local Saskia Millard as well as San Francisco-based Claire Green to take on this linchpin workout and reflect on the idea of barriers.