Low back pain is common in mountain biking due to the sustained flexion of the lumbar spine, particularly during fatiguing hill climbs. In this study, we investigated whether an ergonomic mountain bike saddle including a raised rear, a longitudinal dip, and a subtle lateral instability (the 'Active'-technology) can reduce acute low back pain at the end of a hill climb (>1 h) in a group of mountain bikers with a history of cycling-related low back pain (n = 28). In addition, we conducted a laboratory experiment to investigate the isolated effects of the 'Active'-technology on the cyclists' pelvis and spine motion as well as on the activity of surrounding muscles. The field test demonstrated a significant reduction in numerical low back pain ratings with the experimental saddle compared to the riders' own standard saddle (p = 0.001, strong effect). The laboratory-based data suggested that the 'Active'-technology does lead to potentially beneficial effects on pelvis-spine kinematics and muscle activity, which in combination with an optimised saddle geometry may explain the observed reduction in low back pain following mountain bike hill climbing.
Keywords: Cycling; bike seat; multifidus; overuse injury; principal component analysis.