Acute Effect of Plyometric Exercises on Musculotendinous Properties

This is a single-arm clinical trial aiming to determine the acute effect of one session of plyometric exercises on quadriceps and biceps femoral musculotendinous properties in healthy individuals.

The sample size was determined using G*Power software considering the application of ANOVA: Repeated measures, between factors, 90% power, alpha 0.05. Data from muscle echo intensity of the rectus femoral by Muddle et al. (2019) were considered for this calculation, with an effect size 0.44. A total of 30 individuals was required for this study.

The outcomes will include the muscle and tendon quality, and mechanical properties of the tendon. The assessments will be performed at three different moments: before exercise, immediately after, and 48 hours after exercise.

The data analysis will be performed per protocol. Generalized estimating equations will be used to identify the effects of time followed by Bonferroni posthoc. When effects are found, effect sizes will be estimated. Missing data will be estimated by statistical analysis.

• Plyometric exercises (Other): Plyometric exercises will be composed of vertical jumps, box jumps, half squat jumps, high straight jumps, bounding jumps, drop jumps and 10-m sprint.

Primary outcomes

• Change from baseline of echo intensity of quadriceps and biceps femoral muscles [Baseline, immediately after exercise and up to 48 hours exercise]: Muscle echo intensity will be assessed for transversal and longitudinal ultrasonography images.
• Change from baseline stiffness of patellar tendon [Baseline, immediately after exercise and up to 48 hours exercise]: Patellar tendon stiffness during 5 seconds rampa contraction protocol. Patellar tendon stiffness will be estimate from force/deformation relationship of tendon.
• Change from baseline young modulus of patellar tendon [Baseline, immediately after exercise and up to 48 hours exercise]: Patellar tendon young modulus during rampa contraction protocol. Young modulus will be estimate from force/deformation relationship of tendon normalized to transverse section area of tendon.

Secondary outcomes

• Change from baseline echo intensity of quadriceps and biceps femoral tendons [Baseline, immediately after exercise and up to 48 hours exercise]: Tendons echo intensity will be assessed for transversal and longitudinal ultrasonography images.

Other outcomes

• Change from baseline muscle soreness of quadriceps and biceps femoral muscles [Baseline and up to 48 hours exercise]: Soreness will be measure as treashold of pain feeling while a hand-held dynamometer apply force.

Sex: Male, ages: 18 Years to 30 Years, accepts healthy volunteers

Inclusion Criteria:

* Who practice physical activity (except jump training);
* No previous lower extremity muscle injury at least 6 months before the recruitment;
* No previous lower extremity ligament or tendon injury or surgery;
* No auditory, vestibular, visual or musculoskeletal injuries or disease that limit the execution of the exercise and assessment protocols;
* No hypertension, cardiovascular, or respiratory disease.

Exclusion Criteria:

* Body mass index greater than 30 kg/m².

• Felipe P Carpes, PhD, Study director, Universidade Federal do Pampa
• Marco A Vaz, PhD, Study chair, Federal University of Rio Grande do Sul