Externally cadenced bipodal heel lift test: reproducibility and reference values in healthy adults
Physical resistance. Muscle strength. Vascular diseases. Fatigue.
Introduction: Muscle endurance is an important feature for the prevention of musculotendinous lesions and peripheral vascular system. The heel-rise test (HRT) currently aids in the clinical findings of strength and endurance of the triceps surae muscle during repetitions of the plantar flexion movement. However, the protocols of the test described in the literature have great variability, differing in several parameters such as initial position, achieved height, cadence of execution, balance support, type of foot support, knee positioning, criteria and outcome measures. We believe that the elaboration of a protocol with external cadence (HRTEC) and bilaterl support can be a sensitive and safe instrument to identify the functional limitations. Objectives. The present study had as main objective to elaborate a protocol for applying HRTEC with bilateral support in healthy adults and to evaluate its reliability and intra-rater reproducibility. Secondly, determine the reference values of the bilateral support HRTEC and propose prediction equations for this population. Methods. The study was characterized as observational and transversal, with healthy adults of both sexes, aged between 20 and 59 years, with BMI <30 kg / m2. For the collection of reference values, the application was multicentric (Natal / RN, Curitiba / PR and Belo Horizonte / MG). The analysis of the measurement properties of the test were performed with the data collected in a subgroup of the metropolitan region of Natal / RN. All subjects included in the study were submitted to the protocol with a rate of 60 elevations / minute, starting from 10º of dorsiflexion, to evaluate the number of elevations, the perception of pain before and after the test, pain with 24 hours and 48 hours after the test and the perception of initial and final effort. The test-retest was performed with an interval of one week, for the reliability and reproducibility analysis of the HRTEC protocol. Statistical analysis. The Kolmogorov-Smirnov and Shapiro-Wilk tests were used for data normality. The Mann-Whitney test and the Kruskall-Wallis test with Dunn post-hoc for comparisons between the variables. The Intraclass Correlation Coefficient for intra-rater reliability analysis. The Bland-Altman comparison method for agreement analysis and the Pearson correlation for association between the tests. Results. 140 healthy adults from the metropolitan region of Natal / RN were evaluated, but only 112 (52 men) volunteers, aged 25 (23-33) years for men and 25 (23.2-34) years for women and BMI <25.0 kg / m 2. The test proved to be easy to understand, safe and simple to perform in clinical practice. In the performance outcomes of the total sample, the men presented a better performance with a higher number of elevations (p <0.02), especially in the age group of 20 to 29 years (p = 0.03), compared with the women. The main symptoms reported were burning sensation (54.5%) and fatigue (22.3%). Participants related to the end of the test of moderate intensity 4 (3-6) and graduated with mild intensity 2 (1-3) after 24 hours. Despite this, interest rates increase to 3 (1-5), being more uncomfortable. For the entire sample, the limiting test fatigue had a moderate level of intensity 3 (2-4), with significance before and after the p <0.0001 test. For reliability and reproducibility analysis, we used a sample of 21 adults and found a ICC=0.98, with excellent reliability. Pearson's correlation was r = 0.98, with a coefficient of determination r2 = 0.96 (p <0.0001). The Bland-Altman dispersion model presented a bias of -0.76, with 85% of the sample included within the limits of agreement. Conclusions. HRTEC with bilateral support was considered an easy to perform evaluative method, with clinical practice and standardization of the most adequate and safe positioning for adults, the cadence was adequate to promote the frequency of the movement of plantar flexion and to reach maximum fatigue. In addition, the study showed a good reproducibility of the analyzed variables, confirming the reliability of the test. It was not possible to obtain the reference values and prediction equations due to the small representativeness of the sample from 40 to 59 years old.