Effects of Plyometric Training on Running Biomechanics and Jumping Ability of U14 Athletes.

Young athletes going through growth spurts face particular risk of musculoskeletal problems, and plyometric training, jump-based exercises that use quick, explosive muscle contractions, has been suggested as a way to both protect against injury and improve performance. This trial asked whether adding a short plyometric program to normal training could change jumping ability and running mechanics in track-and-field athletes under 14. Thirty-five young athletes were randomly assigned to continue their usual training alone or add two plyometric sessions per week for four weeks, with jumping and running measured before and after. The broad result was mixed.

There was no overall change over time across the group in most measures, but the intervention group showed a significant improvement in reactive strength index and in leg spring stiffness compared with controls, while jump height and other running measures did not change. This is interesting because it suggests a brief, low-volume program may influence how the body stores and releases elastic energy during movement, even without changing overall jump height. The main limitation is the small sample and short four-week duration, so these findings represent an early, short-term signal rather than a settled conclusion.

If you're a parent or coach of a young athlete, you may wonder whether short jump-training sessions actually help. This study looked at track-and-field athletes under 14, splitting them into two groups: one kept doing normal training, the other added two plyometric jump-training sessions per week for four weeks.

Researchers then measured jumping ability and running technique before and after. The results were mixed rather than clearly positive across the board. Most measures, including how high the athletes could jump, didn't change significantly in either group.

However, two specific measures related to how efficiently the legs absorb and release energy during quick movements did improve more in the group that did the extra jump training compared with those who didn't. This doesn't mean plyometric training makes young athletes jump higher or run faster overall, at least not in this short trial. It suggests a possible effect on a specific aspect of movement efficiency, but with only 35 young athletes studied over just four weeks, this is early evidence rather than a firm answer, and longer or larger studies would be needed to know how meaningful or lasting these changes are.

This is a summary of research, not medical advice. Talk to your own healthcare provider about anything affecting your care.

This single-blind randomized controlled trial enrolled 35 U14 track-and-field athletes (18 female, 17 male; mean age 12.5 years) allocated to a control group continuing usual training or an intervention group adding a low-volume plyometric program twice weekly for four weeks. Outcomes included countermovement jump height, reactive strength index (RSI) from 10-second repeated jumps, and running kinematics during a 3-minute run at 12 km/h, including contact time, flight time, step length, step frequency, power output, and leg spring stiffness (LSS). No main effect of time was found for any variable, but a group-by-time interaction emerged for RSI (p = 0.045) favoring the intervention, alongside a significant post-intervention increase in LSS (p = 0.031).

Countermovement jump height and other running kinematic variables showed no significant change in either group. The findings indicate a selective effect on stretch-shortening cycle function, specifically reactive strength and leg stiffness, without corresponding change in maximal jump height or gross running mechanics. Given the small sample, short four-week intervention, and lack of significant change in most outcomes, these results should be interpreted as a preliminary, short-term signal rather than confirmed evidence of broad performance or biomechanical benefit in this age group.