Tendon Stiffness & Jump Training Comparison
====================
Moran et al. (2023). The effects of plyometric jump training on lower-limb stiffness in healthy individuals: A meta-analytical comparison. Journal of Sport and Health Science, 12, 236-245.
====================
>Most sports that require running, jumping, and change of direction utilize a spring-like effect from the tendons of their athletes.
>This effect, the stretch-shortening cycle (SSC), takes advantage of the stored elastic energy within the tendons to create magnified force outputs.
>Tendon stiffness is the mechanical ability to resist deformation (stretch) which results in a stronger tendon with improved force transmission capability. This tendon quality opposes compliance/elasticity which leads to losses of energy (hysteresis) and potentiates injury.
>Increased tendon stiffness comes from improved collagen architecture and tendon hypertrophy via increased collagen synthesis.
>Increased stiffness leads to improved athletic performance specific to sprinting and jumping while simultaneously attenuating injury risk.
>Plyometric jump training (PJT) is a highly common method for targeting tendons and lower limb stiffness. Conventional thought would lead one to believe that the SSC found in braking-propulsive jumping exercises best develop tendon qualities. However…
====================
>In reality, PJT has relatively small effect sizes on tendon stiffness.
>Furthermore, PJT’s effect sizes seem to benefit untrained athletes most and this effectiveness should be expected to diminish relatively quickly over time.
>PJT does not appear to be the best way to enhance tendon stiffness when compared with traditional resistance training. This is especially true when considering long-term development models for athletes.
>Interestingly, PJT has an inverse dose-response relationship where low to moderate amounts can be beneficial while higher volumes are found to be negatively impactful leading to tissue degradation.
>Ideal amounts of PJT were shown to be 1-2 sessions per week, with fewer than 250 total jumps (>500 jumps were shown to have negative effects), and with program durations exceeding 7 weeks of training.
>Mechanistically, traditional resistance training is likely more effective for tendon development because it inherently creates higher levels of tendon strain across longer durations of time.
====================
Take-Home:
>Plyometric jump training can be an effective means of improving tendon stiffness with effect sizes being more favorable for untrained individuals.
>Traditional resistance training, and not plyometric jump training, is probably the best way to enhance tendon quality, size, and strength in the long-term.
>Because plyometric exercises have an inverse dose-response relationship, high volumes are unnecessary and even detrimental. Therefore, if an athlete is already participating in heavy sport practices with lots of sprinting and jumping, it may be wise to omit plyometrics from the strength training program.