Dados do Trabalho

Título

The effect of handrail support on movement acceleration during CPET in young adults

Introdução e Objetivo

Guidelines recommend the use of handrail support during Exercise treadmill testing (ETT) in cases of balance disorders, decreased muscle strength, altered neuromotor coordination and fear of falling. Other fact observed that the physical effort undergoes changes in the ETT, and a possible variable to be evaluated would be the acceleration of the movement. Therefore, this study analyzed the movement-acceleration (MA) in two different forms of ETT.

Casuística e Método

Cross-sectional descriptive study, with sixty university students (20.98 ± 2.61 years) of both genders volunteered to be examined, undergoing two ETT following Ellestad's protocol on the treadmill, during non-consecutive days. The first test (T1) was executed with the participants holding onto the treadmill's handrail supports, and after seven days a second test (T2) was executed without holding onto the handrail. The MA was measured on both exams with the aid of an accelerometer (GT3x, Acthigraph). In the test, heart rate, blood pressure and subjective perception of muscular and respiratory effort were also evaluated.

Resultados

The oxygen consumption estimative (VO2) in T1 was 10,57% higher (p<0.000) when compared evenly with T2. The expenditure energy, in kcal, the metabolic units and the time dispended on both soft and vigorous intensity were significantly higher on T1. Lastly, the measurements of MA on the vertical, horizontal, diagonal and magnitude vectors were significantly superior on T2 on the three first stages and on T1 on the fourth stage, in the vertical axis and in the magnitude vector; in the other axis, the acceleration in T2 was higher in all stages. In the later stages, acceleration stabilization has occurred, regardless of the axis and the mode of execution.

Discussão

It was found that in the mid-lateral and anteroposterior axes of the accelerometer, the acceleration of movement was superior when performed the ETT not holding on the handrail support (T2). In addition, in the vertical axis and in the magnitude vector, a greater acceleration in T2 was observed only in the first 3 stages, and in stages 4, 5 and 6 the acceleration was greater when the front bar of the treadmill was used as support (T1). In addition, a longer duration of the ETT was observed in T1, which resulted in a higher energy expenditure and in a higher estimate of oxygen consumption. Although there are several studies demonstrating the changes that occur in HR, BP and VO2 during the exercise test, this is the first research to demonstrate what occurs with the acceleration of movement during ETT in two different forms of execution and possible clinical applications. The greater acceleration on T2, in all stages, on the mid-lateral and anteroposterior axis, can be explained by the fact that the movement is freer (without holding on the treadmill support), requiring a greater demand and range of movement to maintain the speed and inclination imposed by the protocol, resulting in greater acceleration in these vectors. Considering that the movement performed during an ergometric test involves a horizontal displacement, we infer that the anteroposterior axis is the main determinant of the dynamics of movement.

Conclusão

On executing the ETT with the use of the treadmill's handrails causes less acceleration of movement in the medial-lateral and anteroposterior axes, making the effort performed and the hemodynamic results more distant from reality for guidance in exercise prescription, as well as possible underestimation of diagnoses and prognosis when performed ETT in patients. Therefore, it is necessary to standardize the way of performing the ETT to avoid inadequacy in the interpretation of the results observed during and at the end of exercise tests, especially when ergospirometry is not used.