Biomechanics Responses to Power and Strength Combined Training

Lower Extremities Biomechanics Responses to Power and Strength Combined Training in Adults: a Randomized Clinical Trial

Anterior cruciate ligament (ACL) is the most frequently injured knee ligament during performance of recreational activities and sports. In the United States, the annual incidence is 68.6 per 100,000 people per year and in Brazil, the estimation of ACL reconstruction increases 64%. There are different biomechanical profiles of risk factors for an ACL injury variable, the ligament dominance, the quadriceps dominance, the trunk dominance, and the leg dominance. Thus, the purpose of this study is to investigate the biomechanics adaptations after power and strength combined training protocol in healthy individuals. A second aim is to determine the effect of the training on knee injury risk factors.

This is a parallel randomized clinical trial comparing the effect of combined training with power and strength exercises on lower extremity biomechanics in healthy individuals.

The sample size was calculated with G*Power software using the ANOVA: Repeated measures, within-between interaction, 90% power, alpha 0.05, and 30% drop-out. Data from the tuck jump test (knee flexion range) by Makaruk (2014) were considered for this calculation with effect size 0.46. Thus, a total of 32 individuals (16 per group) is required for this study. To ensure the proper simple size, after collecting the first five participants per group, the sample size will be checked again.

The participants will be randomized in experimental and no intervention groups inside each risk profile group. Randomization ratio will be 1:1 and interventions will last 10 weeks, with two weekly sessions for the exercise arms.

The outcomes will include functional clinical tests, kinematic and kinetic variables during landing tasks, and strength of knee and hip muscles.

The data analysis will be performed by intention to treat and per protocol. Generalized estimating equations will be used to identify interaction effects of groups and time followed by Bonferroni post-hoc. When effect are found, effect size will be estimated. Missing data will be estimate by statistical analysis.

Inclusion Criteria:

• Male sex;
• Age between 18 and 30 years old;
• Who practice physical activity (except: strength and jump training) between 80 and 150 minute per week;
• No previous muscle lower extremity injury at least 6 months prior to recruitment;
• No previous ligament and tendon lower extremity injury or surgery;
• No auditory, vestibular, visual or musculoskeletal injuries or disease that impairment the execution of assessments or training protocol;
• No hypertension, cardiovascular or respiratory disease.

Exclusion Criteria:

• Body mass index greater than 35 kg/m².