Performance in vertical jump tests, such as jump height and the reactive strength index (RSI), are important metrics for clinicians to monitor during the rehabilitation of individuals following anterior cruciate ligament reconstruction (ACLR). Although force platforms are considered the gold standard for this type of measurement, their limited accessibility and high cost make them unsuitable for clinical settings. In this context, mobile applications, such as the My Jump Lab app, have emerged as potential alternative tools for jump assessment in clinical environments.

To verify the concurrent validity of the My Jump Lab app compared to a force platform (gold standard) in assessing vertical jump performance in individuals who have undergone anterior cruciate ligament reconstruction.

A concurrent validity study following the Guidelines for Reporting Reliability and Agreement Studies (GRRAS). Individuals of both sexes who had undergone ACLR and were eligible to perform jump tests between the sixth and twenty-fourth postoperative month were recruited. Participants were instructed to complete an assessment form with clinical and anthropometric characteristics and then underwent a five-minute warm-up on a stationary bicycle. They performed two vertical jumps: single-leg vertical jump (SLVJ) and single-leg drop jump (SLDJ). A researcher not involved in the assessment randomized the limbs (operated and non-operated) to determine which limb the participant would start the tests with. The evaluation of jumps using the My Jump Lab app was conducted simultaneously with the force platform assessment (Bertec® Model FP4060-08-1000) by two blinded assessors, each responsible for analyzing the data from one instrument. The smartphone (iPhone 11) was positioned 1.5 meters from the platform with its lenses close to the ground. The jump height in SLVJ and SLDJ and the RSI in SLDJ were collected. Pearson correlation was used to analyze concurrent validity, and Bland-Altman plots were used to assess the agreement between the force platform and the My Jump Lab app.

Eighty participants with ACLR were included in the evaluation. A total of 320 jumps were analyzed using the app. The jump height in SLVJ and SLDJ and the RSI in SLDJ assessed by the My Jump Lab app showed a very strong correlation with the jump height in SLVJ (r = 0.982, p < 0.001) and SLDJ (r = 0.977, p < 0.001) and the RSI in SLDJ (r = 0.972, p < 0.001) assessed by the force platform. The agreement analysis using Bland-Altman plots did not reveal any systematic bias in the results obtained by either method.

The My Jump Lab app is a valid tool for assessing vertical jump performance in individuals who have undergone anterior cruciate ligament reconstruction.

Due to the high cost of gold-standard instruments, such as the force platform, mobile applications like My Jump Lab offer a more economical and accessible alternative for use in clinical practice.