1
Acta
PHYSIOLOGICA &
PHARMACOLOGICA
Bulgarica
Research article
Modified Treadmill Protocol for Evaluation of Physical
Fitness in Pediatric Age Group - Comparison with Bruce
and Balke Protocols
B. Marinov1, S. Kostianev1, T. Turnovska2, 1Department of
Pathophysiology and 2Department of Hygiene & Ecology, Higher
Medical Institute, Plovdiv, Bulgaria.
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.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.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.min-1.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.min-1.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±2.3ml.min-1.kg-1) adequate for evaluation of childrens exercise capacity. Childrens 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.Acta Physiol. Pharmacol. Bulg., 27 (2003) 1-pp.
KEY WORDS: Treadmill protocols; Exercise tolerance in children; Perceived exertion; Borg score.
Received February 21, 2002
INTRODUCTION
Cardiopulmonary exercise testing not only mea-
sures the efficiency and capacity of the oxygen trans-
port systems but can also reveal the causes for childrens
exercise limitation (Armstrong and Welsman, 1994).
Historically, the protocols used for exercise testing
have been based on tradition, convenience or both.
In the past decade a considerable amount of research
has focused on the effect of the exercise protocol on
test performance, including exercise tolerance, diag-
nostic accuracy and gas exchange (Myers et al.,
2000). Childrens performance largely depends on the
exercise modality and the testing protocol (Washing-
ton et al., 1994), though special considerations have
to be taken to tailor the workload to pediatric popu-
lation and ensure standard conditions. There are
several widely used treadmill protocols for assess-
ment of childrens physical capacity but none of them
is compliant with the modern guidelines for paediat-
ric exercise testing (Washington et al., 1994). There-
fore there is a necessity of a treadmill protocol ap-
propriate either for a clinical use or as a reliable
screening method. Such protocol is intended to avoid
both an excessive duration and excessive workload
increments (Myers et al., 1991; Buchfuhrer et al.,
1983). Since pediatric patients are of various ages and
sizes, sometimes disabled with respect to mobility and
muscular coordination the new protocol must be
designed to change either speed or grade from one
stage to the next (Lehman et al., 1997)
The aim of this study was to compare classical
Bruce and Balke treadmill protocols with our modi-
Corresponding author: Blagoi Marinov, MD, 15A Vasil Aprilov
Blvd, Higher Medical Institute, Pathophysiology Department,
Plovdiv 4002, Bulgaria. Phone: (+359 32) 602227;
e-mail: blim@plovdiv.techno-link.com
