Modified treadmill protocol for evaluation of physical fitness in pediatric age group--comparison with Bruce and Balke protocols.

The aim of this study was to compare classical Balke and Bruce protocols with our modification of Balke protocol in pediatric cardiorespiratory diagnostics. The modification of Balke consists of nine stages per 1 min at a constant velocity of 5.6 km x h(-1) and increasing elevation from 6% to 22% in 2% increments. Sixty healthy children (mean age = 13.3+/-0.2 years; BMI = 18.8+/-0.6 kg x m(-2); mean +/- 95% CI), divided into three groups of 20 children each, matched by age, height and BMI performed integrative cardiopulmonary exercise testing using one of the treadmill protocols mentioned. At the end of each exercise increment and throughout the recovery period the children were asked to rate the perceived exertion (RPE) using the Borg Category Ratio scale--CR-10. Exercise results showed that Balke protocol had the longest duration (21.7+/-0.6 min.) and the lowest values for VO2/kg (34.2+/-1.8 ml x min(-1) x kg(-1)) due to the minimal workload increments. Bruce protocol had intermediate duration (14.9+/-1.1 min.) and children achieved the highest VO2/kg (48.6+/-2.7 ml x min(-1) x kg(-1)) but the test is symptom-limited which is ethically unacceptable in childhood. Exercise data revealed that our modification of the classical Balke protocol had an optimal duration (11 min.) and yielded peak VO2/kg values (39.4+/-2.3 ml x min(-1) x kg(-1)) adequate for evaluation of children's exercise capacity. Children's ratings of perceived exertion were highest in Bruce protocol (6.5+/-0.4) and lowest in the original Balke protocol (4.5+/-0.8). In conclusion, the modification of Balke protocol is suitable and reliable for screening and clinical testing in pediatric age group.