Revista Brasileira de Medicina do Esporte
Print version ISSN 1517-8692
MARINS, João Carlos Bouzas; LUIZ, Adriano; MONTEIRO, André and JESUS, Geraldo de. Validation of the measuring time of the heart rate after submaximal physical exercise at 50% and 80%. Rev Bras Med Esporte [online]. 1998, vol.4, n.4, pp. 114-119. ISSN 1517-8692. http://dx.doi.org/10.1590/S1517-86921998000400004.
The purpose of this study was to evaluate the existence of significant different between the recovery heart rate, measured at different intervals of time after physical exercise (6, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 seconds, respectively) and the exercise heart rate. Twenty-six voluntary subjects at ages varying from 19 to 26 years were evaluated. All were male, non-athletes, nonsmokers, with or without regular practice of physical exercise. The data were collected at the Laboratory of Human Performance of the Department of Physical Education, at the University of Viçosa. State of Minas Gerais, Brazil. The instrument used for physical effort was "Movimento 2000" cycloergometer and "Polar Acurex" cardiotachometer was used for heart rate measurements. The protocol included the measurement of the heart rate recovery curve during one minute after a bout of submaximal exercise, characterizing a time of 10 minutes at steady state in two situations: (a) 50% and (b) 80%. For the target heart rate (THR) calculation, the following formula proposed by Karvonen was used: THR = % (Max-HR - RestHR) + RestHR. After 10 minutes of steady state, the subject was instructed to interrupt the exercise completely, starting a passive process of recovery. The last HR during effort and the HR at the following intervals after effort were recorded: 6, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 seconds. The only non-significant result (p > 0.05) obtained was for the 6-second partial measurement, both for the effort at 50% and 80%; the differences of the values obtained for the HR from the 10-second partial measurement and beyond it were significant. With the results obtained in this study, it is possible to conclude that the ideal recording of the HR after a submaximal exercise at 50 and 80% of MaxHR should encompass a time of approximately 6 seconds. The 10-second partial measurement, albeit considered statistically significant and different, presented in absolute values a reduction that in practice does not interfere in the planning of the intensity curve. The collection of HR data using the 15-seconds partial measurement, generally used by most physical education instructors, will frequently induce misinterpretation as to the intensity proposed by the exercise, which will therefore modify incorrectly the planning of the training.
Keywords : Sport training; Heart rate; Exercise prescription.