Effects of plyometric training on Achilles tendon properties and shuttle running during a simulated cricket batting innings

The aim of this study was to determine whether intermittent shuttle running times (during a prolonged, simulated cricket batting innings) and Achilles tendon properties were affected by 8 weeks of plyometric training (PLYO, n = 7) or normal preseason (control [CON], n = 8). Turn (5-0-5-m agility) and 5-m sprint times were assessed using timing gates. Achilles tendon properties were determined using dynamometry, ultrasonography, and musculoskeletal geometry. Countermovement and squat jump heights were also assessed before and after training. Mean 5-0-5-m turn time did not significantly change in PLYO or CON (pre vs. post: 2.25 ± 0.08 vs. 2.22 ± 0.07 and 2.26 ± 0.06 vs. 2.25 ± 0.08 seconds, respectively). Mean 5-m sprint time did not significantly change in PLYO or CON (pre vs. post: 0.85 ± 0.02 vs. 0.84 ± 0.02 and 0.85 ± 0.03 vs. 0.85 ± 0.02 seconds, respectively). However, inferences from the smallest worthwhile change suggested that PLYO had a 51-72% chance of positive effects but only 6-15% chance of detrimental effects on shuttle running times. Jump heights only increased in PLYO (9.1-11.0%, p < 0.050). Achilles tendon mechanical properties (force, stiffness, elastic energy, strain, modulus) did not change in PLYO or CON. However, Achilles tendon cross-sectional area increased in PLYO (pre vs. post: 70 ± 7 vs. 79 ± 8 mm², p < 0.01) but not CON (77 ± 4 vs. 77 ± 5 mm², p > 0.050). In conclusion, plyometric training had possible benefits on intermittent shuttle running times and improved jump performance. Also, plyometric training increased tendon cross-sectional area, but further investigation is required to determine whether this translates to decreased injury risk.