Obese locomotion on a positive and negative slope at iso-intensity: outcomes related to energetics, mechanics, perceived exertion, and hemodynamics. A study protocol. v1

The main objective of this study is to propose a form of walking/running protocol that is capable of evaluating energy expenditure at different types of slopes, considering the same relative intensities (iso-intensity conditions), as well as to assess biomechanical and hemodynamic factors that may be associated. 11 obese adult men (BMI between 30 kg.m-2 and 39.9 kg.m-2) aged between 18 and 35 years, physically inactive. Assessments will be carried out on six different days. On the first day, body composition, familiarization with the equipment, and a maximum incremental test without slope. In the next two days, the maximums tests in positive and negative slope will be performed. In the other three days, biomechanical, energetics, and cardiac variables will be collected in the following conditions: fixed speed (4.5 km.h-1), speed relative to the first, and the second ventilatory threshold, being one day for tests on the positive slope, one on the negative slope and one without slope. From the second day, the tests will be distributed in random order and with an interval of, at least, 72 hours between tests. Metabolic data will be obtained using a gas analyzer, biomechanical data will be obtained through a kinematics system, with six infrared cameras, data Ground Reaction Forces (GRF) are obtained through force sensors installed on the treadmill, and hemodynamic parameters using a Signal-Morphology impedance device. The primary outcome is energy expenditure concerning slopes and speeds and the secondary outcomes are the mechanical work, mean GRF, and hemodynamic aspects. The data will be described by the mean and standard error values. The interactions between slopes and speeds will be tested with Generalized Estimating Equations (GEE) and Bonferroni post-hoc, adopting a significance level (α) of 0.05. Also, effect sizes (ES) will be calculated. The energy expenditure should be greater on the positive slope at all speeds. Higher production of positive mechanical work is expected on the positive slope and the impact peaks should be less in this condition. The negative slope should enable higher speeds relative to the thresholds, as well as lower cardiovascular load.