Effects of Foam Rolling on the Plantar Flexors' Properties

Self-massage is a set of therapeutic techniques performed by the individual using instruments such as a foam roller (i.e., foam rolling \[FR\]). This technique has been used in rehabilitation to recover myofascial dysfunctions and in physical/sports training, to improve performance in functional and sports activities. Possible changes in the muscle\'s and tendon\'s mechanical properties may help to explain the FR effects, however, the dose-response relationship is not clear acutely. Furthermore, body composition also seems to influence the pressure applied to the different tissues during FR, since it can attenuate the forces applied on the tissues. Therefore, the aim of this study is to verify the acute effects of different FR volumes on the plantar flexors\' musculotendinous properties in healthy individuals. Twenty healthy subjects (male and female) aged between 18-35 years will perform three different FR conditions: FR90 (3x30s), FR180 (3x60s), and a control condition (CTRL; without the application of any intervention) with a seven-day wash-out period. The Achilles tendon morphological, mechanical, and material properties, medial gastrocnemius passive muscular stiffness, plantar flexors\' muscle architecture, and the adipose tissue\'s thickness, skin temperature and the jump height (assessed during the unilateral countermovement jump) will be obtained. Assessments will be carried out before and immediately after the FR application in the different conditions. Descriptive statistics (mean, standard deviation, and standard error) will be used to present the results. The normality and sphericity of the data will be evaluated using the Shapiro-Wilk and Mauchly tests, respectively. A two-way ANOVA (condition \[FR90, FR180, and CTRL\] and moments \[pre- and post-intervention\]) will be used to compare the results. A post-hoc Bonferroni test will be used to find possible differences. A Pearson product-moment correlation test (parametric data) or a Spearman correlation test (non-parametric data) will be used to verify the association between the adipose tissue\'s thickness and the evaluated parameters. The effect size (Cohen\'s d) of each condition will be obtained. Responsiveness to conditions (FR90, FR180, and CTRL) will be determined using the typical error.