Achilles tendinopathy is an overuse injury affecting jumping athletes, associated with the accumulation of microdamage due to repetitive tendon strain. Surface and footwear modifications may influence tendon strain magnitude. The purpose of this thesis was to examine the influence of surface and footwear modifications on Achilles tendon strain during vertical countermovement jump landings and to quantify the relationship between tendon strain and accelerometer measures. The parameters were quantified for three shoes (Boost™, 55C, and 70C) and three surfaces (ACS, BC3, and MVP) using motion capture, accelerometry, and dynamometry-ultrasound measures. Surface and footwear influenced Achilles tendon strain;​ strain was lower in the Boost™ shoe and MVP surface conditions. Differences in strain could be due to stiffness or other material properties of the shoes and surfaces. Only weak correlations were found between tendon strain and accelerometer measures, suggesting that data obtained from accelerometers may not reflect internal loading.