Does trampoline or hard surface jumping influence lower extremity alignment?
Kiyokazu Akasaka, Akihiro Tamura, Aoi Katsuta and 5 others
PMID 29643592WHAT IT FOUND
In 20 healthy young women, repeated jumping changed landing mechanics.
Knee extensor moment was greater after trampoline than ground, and both trampoline and ground increased vertical landing force.
Key findings
01Repeated trampoline jumping increased peak vertical ground reaction force from 2.40 ± 0.68 to 2.77 ± 0.87 N/kg (p=0.001), hip extensor moment from 2.63 ± 2.55 to 3.16 ± 3.07 Nm/kg (p=0.02), knee extensor moment from 1.51 ± 0.60 to 1.67 ± 0.72 Nm/kg (p=0.02), hip adduction angle from −1.1 ± 6.4° to 0.7 ± 6.4° (p=0.005), and decreased hip flexion angle from 54.2 ± 12.2° to 51.2 ± 13.2° (p=0.03).
02Repeated ground jumping increased peak vertical ground reaction force from 2.21 ± 0.52 to 2.61 ± 0.61 N/kg (p=0.004), ankle dorsiflexion angle from 33.2 ± 6.6° to 35.0 ± 5.9° (p=0.002), and hip extensor moment from 2.08 ± 0.74 to 2.74 ± 0.94 Nm/kg (p=0.02).
03After exercise, knee extensor moment was greater after trampoline than ground (1.67 ± 0.72 Nm/kg vs 1.53 ± 0.43 Nm/kg, p=0.02), but vertical ground reaction force and lower extremity joint angles did not differ significantly between surfaces (p>0.05).
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The sample was 20 healthy young females, so it does not show what happens in older adults, males, injured people, or patients with musculoskeletal conditions. The study measured immediate landing biomechanics after repeated jumping, not long-term training effects, symptoms, function, or injury outcomes. The outcomes were laboratory biomechanical variables, not clinical outcomes such as pain, balance, or injury risk. Trials were excluded if balance was lost, and only the middle three successful drop vertical jumps were analysed, so the findings may not represent fatigued or uncontrolled landings. Group sizes were small (12 in Group A and 8 in Group B). The paper does not report dropouts or how many participants were excluded after random assignment.
The easy way to misread this
Do not treat these short-term biomechanical changes as evidence that trampoline jumping prevents injury or improves function. The study measured 20 healthy young women before and after repeated jumping, and it did not test patients or long-term outcomes.