567
Reliability of the Rating of Perceived Exertion at Ventilatory Threshold in Children A. D. Mahon, M L. Marsh 1-luman Performance Laboratory, Ball State University, Muncie, Indiana 47306
A. D. Mahon and M L. Marsh, Reliability of the Rating of Perceived Exertion at Ventilatory Threshold in Children. lot J Sports Mcd, Vol. 13, No. 8, pp 567—571, 1992.
Accepted after revision: August 20, 1992
The purpose of this study was to examine the reliability of the rating of perceived exertion (RPE), using the Borg 6—20 scale, at ventilatory threshold (VT) in children. Thirty children (19 male, 11 female) with a mean
SD age of 10.4 1.1 yrs performed two graded exercise tests for the assessment of VT and VO2max. RPE was recorded throughout each exercise test. There were no significant (p>O.O5) differences between the mean VO2max (50.9
vs 51.0±5.7m1kg' min'; r=0.95) or the mean ml kg' . min; r = 0.87) vs 36.7
V02 at VT (36.2
between trials. The mean RPE at VT during trial 1 (12.4 2.7) was significantly higher than during trial 2 (11.4±3.3; p 26
uJ
> 24 22
I
.1
a
•
w
> 24
z •a.•?a•
a
22
U
VT
20 0
a
30
I
5 10 15 20 25 30 35 40 45 50 55 60
0
5 10 15 20 25 30 35 40 45 50 55 0
V02 (ml . kg1 min1)
'O2 (ml . kg1 m1n1)
b
Methods
cise test. Ventilation was measured during inspiration using a Parkinson-Cowan dry gas meter. Expired concentrations of 02 and CO2 were sampled from a mixing chamber and analyzed using an Applied Electrochemistry S-3A analyzer and Sensormedics LB-2 analyzer respectively. Prior to each exercise test, the 02 and CO2 analyzers were calibrated with a gas mixture of known composition. HR was monitored continuously and recorded every 15 seconds using a telemetry HR monitor
Thirty-five children (23 males, 12 females) between 8 and 12 years of age volunteered to participate as subjects in this study. Parental consent was obtained for all subjects in accordance with the guidelines established by the Institutional Review Board. Three children were removed from the data analysis for failure to achieve VO2max on one or both of the tests. Two other children were deleted from the study due to the inability of the investigators to detect VT. As a result, 30 children were included in the data analysis. For each child, a minimum of two days and a maximum of 16 days separated each exercise test (mean = 7.4 days). The mean age, height and weight of the subjects on the first trial was 10.4 1.1 yrs, 142.9 7.7 cm, and 36.3 8.4 kg respectively. All subjects were required to perform two graded exercise tests on a motor driven treadmill (Quinton Instruments, Model 1860) for the assessment of VT and VO2max. Prior to each exercise test, the subject's height and weight were measured. Before the first exer-
(Polar Electro, Finland). Every 30 seconds, the RPE scale (Borg 6—20 scale) was placed within reach of the subject, permitting the child to point to a number on the scale that corresponded to his or her effort. Prior to the first exercise test, all subjects read a standardized set of instructions recommended for children to
cise test, each subject was allowed to practise walking and running on the treadmill to become familiar with the proce-
alent for V02 (V/V02) and ventilatory equivalent for VCO2
dures. During this practice period, a comfortable running speed
(134.0 to 174.2m.miir1) was established on an individual basis.
During the graded exercise test, the subjects breathed through a Hans-Rudolf 2-way (model 2600) breathing valve (deadspace 49 ml) with a noseclip in place. The protocol
began with all subjects walking at 80.4mmin-1 for one minute. The speed of the treadmill was then increased every minute by 13.4 rn min until attainment of the subject's predetermined running speed. Thereafter, the speed remained constant, but the elevation was increased by 2.0 % every minute
until the achievement of VO2max. Criteria for VO2max achievement included (1) an increase in V02 2.0 ml kg'' mm-1 with further increases in work rate; (b) HR> 195 bpm; or (c) RER> 1.0 (3). All subjects were required to attain a mini-
mum of two out of the three criteria. Specifically, in the first and second trial, respectively, 77% and 53 % of the children attained the plateau criterion; while 80% and 87% of the children achieved the HR criterion. All children achieved the RER criterion in both trials. V02 was measured continuously via open circuit spirometry and recorded every 30 seconds during the exer-
become acquainted with using the Borg scale (3). No instructions were given prior to the second exercise test.
VT was defined as the Vo2 corresponding to the disproportionate increase in ventilation (VE) during graded exercise. VT was assessed from graphs of the ventilatory equiv(VE/VCO2) plotted against V02. If VT was not detectable using this procedure, VE plotted against Vo2 was used as an alterna-
tive method. The criteria for the determination of VT were an increase in VE/V02 without a concomitant increase in VE/ VCO2 or a departure from linearity in the VE versus V02 plot (8,11). VT plots were coded so as not to identify the subject and
were assessed independently by three individuals. In cases of disagreement, the two closest determinations were averaged and used in the data analysis. A representative plot of VT determination using VE/V02 and VE/VCO2 is provided in Fig. 1.
A one-way analysis of variance using a repeated measures design was employed to determine whether
statistical differences existed between trials for the cardiorespiratory responses and RPE at VT and at VO2max. Testretest reliability coefficients were determined to examine the reliability of the V02 at VT, the RPE at VT, and VO2max of the
two trials. An alpha level of p0.05 was used in all cases to establish statistical significance.
Results
The mean± SD cardiorespiratory responses and RPE at VT and VO2max as well as the test-retest reliability correlations are outlined in Table 1. There was no significant
Downloaded by: East Carolina University. Copyrighted material.
Fig. 1 Typical plot of VT determination.
mt. J Sports Med. 13 (1992) 569
RPE in Children Table 1 Cardiorespiratory responses and APE at VT and VO2max.
Mean±SD
Mean±SD
Trial 1
Trial 2
r
Ventilatory Threshold 0.22 4.4 7.2
1.29
\/02 (I min1) V02 (ml. kg1 . min1)
36.2 71.4 169.3
VT (%VO2max) HR (bpm) RPE
12.4
14.4 2.7
1.32
36.7 71.9 168.7 11.4
0.23 4.5 6.9 13.2
33*
0.93 0.87 0.77 0.78 0.78
45
b
40
- 35 E
o 30
Tria1i
1.81
50.9 203.6
0.29 6.0 6.7
1.08± 0.04 3.6 17.8
1.83± 0.29 5.7 202.3 6.8 1.09± 0.04 3.9 17.3 51.1
0.98 0.95 0.84 0.49 0.87
(n = 30); p
Reliability of the Rating of Perceived Exertion at Ventilatory Threshold in Children A. D. Mahon, M L. Marsh 1-luman Performance Laboratory, Ball State University, Muncie, Indiana 47306
A. D. Mahon and M L. Marsh, Reliability of the Rating of Perceived Exertion at Ventilatory Threshold in Children. lot J Sports Mcd, Vol. 13, No. 8, pp 567—571, 1992.
Accepted after revision: August 20, 1992
The purpose of this study was to examine the reliability of the rating of perceived exertion (RPE), using the Borg 6—20 scale, at ventilatory threshold (VT) in children. Thirty children (19 male, 11 female) with a mean
SD age of 10.4 1.1 yrs performed two graded exercise tests for the assessment of VT and VO2max. RPE was recorded throughout each exercise test. There were no significant (p>O.O5) differences between the mean VO2max (50.9
vs 51.0±5.7m1kg' min'; r=0.95) or the mean ml kg' . min; r = 0.87) vs 36.7
V02 at VT (36.2
between trials. The mean RPE at VT during trial 1 (12.4 2.7) was significantly higher than during trial 2 (11.4±3.3; p 26
uJ
> 24 22
I
.1
a
•
w
> 24
z •a.•?a•
a
22
U
VT
20 0
a
30
I
5 10 15 20 25 30 35 40 45 50 55 60
0
5 10 15 20 25 30 35 40 45 50 55 0
V02 (ml . kg1 min1)
'O2 (ml . kg1 m1n1)
b
Methods
cise test. Ventilation was measured during inspiration using a Parkinson-Cowan dry gas meter. Expired concentrations of 02 and CO2 were sampled from a mixing chamber and analyzed using an Applied Electrochemistry S-3A analyzer and Sensormedics LB-2 analyzer respectively. Prior to each exercise test, the 02 and CO2 analyzers were calibrated with a gas mixture of known composition. HR was monitored continuously and recorded every 15 seconds using a telemetry HR monitor
Thirty-five children (23 males, 12 females) between 8 and 12 years of age volunteered to participate as subjects in this study. Parental consent was obtained for all subjects in accordance with the guidelines established by the Institutional Review Board. Three children were removed from the data analysis for failure to achieve VO2max on one or both of the tests. Two other children were deleted from the study due to the inability of the investigators to detect VT. As a result, 30 children were included in the data analysis. For each child, a minimum of two days and a maximum of 16 days separated each exercise test (mean = 7.4 days). The mean age, height and weight of the subjects on the first trial was 10.4 1.1 yrs, 142.9 7.7 cm, and 36.3 8.4 kg respectively. All subjects were required to perform two graded exercise tests on a motor driven treadmill (Quinton Instruments, Model 1860) for the assessment of VT and VO2max. Prior to each exercise test, the subject's height and weight were measured. Before the first exer-
(Polar Electro, Finland). Every 30 seconds, the RPE scale (Borg 6—20 scale) was placed within reach of the subject, permitting the child to point to a number on the scale that corresponded to his or her effort. Prior to the first exercise test, all subjects read a standardized set of instructions recommended for children to
cise test, each subject was allowed to practise walking and running on the treadmill to become familiar with the proce-
alent for V02 (V/V02) and ventilatory equivalent for VCO2
dures. During this practice period, a comfortable running speed
(134.0 to 174.2m.miir1) was established on an individual basis.
During the graded exercise test, the subjects breathed through a Hans-Rudolf 2-way (model 2600) breathing valve (deadspace 49 ml) with a noseclip in place. The protocol
began with all subjects walking at 80.4mmin-1 for one minute. The speed of the treadmill was then increased every minute by 13.4 rn min until attainment of the subject's predetermined running speed. Thereafter, the speed remained constant, but the elevation was increased by 2.0 % every minute
until the achievement of VO2max. Criteria for VO2max achievement included (1) an increase in V02 2.0 ml kg'' mm-1 with further increases in work rate; (b) HR> 195 bpm; or (c) RER> 1.0 (3). All subjects were required to attain a mini-
mum of two out of the three criteria. Specifically, in the first and second trial, respectively, 77% and 53 % of the children attained the plateau criterion; while 80% and 87% of the children achieved the HR criterion. All children achieved the RER criterion in both trials. V02 was measured continuously via open circuit spirometry and recorded every 30 seconds during the exer-
become acquainted with using the Borg scale (3). No instructions were given prior to the second exercise test.
VT was defined as the Vo2 corresponding to the disproportionate increase in ventilation (VE) during graded exercise. VT was assessed from graphs of the ventilatory equiv(VE/VCO2) plotted against V02. If VT was not detectable using this procedure, VE plotted against Vo2 was used as an alterna-
tive method. The criteria for the determination of VT were an increase in VE/V02 without a concomitant increase in VE/ VCO2 or a departure from linearity in the VE versus V02 plot (8,11). VT plots were coded so as not to identify the subject and
were assessed independently by three individuals. In cases of disagreement, the two closest determinations were averaged and used in the data analysis. A representative plot of VT determination using VE/V02 and VE/VCO2 is provided in Fig. 1.
A one-way analysis of variance using a repeated measures design was employed to determine whether
statistical differences existed between trials for the cardiorespiratory responses and RPE at VT and at VO2max. Testretest reliability coefficients were determined to examine the reliability of the V02 at VT, the RPE at VT, and VO2max of the
two trials. An alpha level of p0.05 was used in all cases to establish statistical significance.
Results
The mean± SD cardiorespiratory responses and RPE at VT and VO2max as well as the test-retest reliability correlations are outlined in Table 1. There was no significant
Downloaded by: East Carolina University. Copyrighted material.
Fig. 1 Typical plot of VT determination.
mt. J Sports Med. 13 (1992) 569
RPE in Children Table 1 Cardiorespiratory responses and APE at VT and VO2max.
Mean±SD
Mean±SD
Trial 1
Trial 2
r
Ventilatory Threshold 0.22 4.4 7.2
1.29
\/02 (I min1) V02 (ml. kg1 . min1)
36.2 71.4 169.3
VT (%VO2max) HR (bpm) RPE
12.4
14.4 2.7
1.32
36.7 71.9 168.7 11.4
0.23 4.5 6.9 13.2
33*
0.93 0.87 0.77 0.78 0.78
45
b
40
- 35 E
o 30
Tria1i
1.81
50.9 203.6
0.29 6.0 6.7
1.08± 0.04 3.6 17.8
1.83± 0.29 5.7 202.3 6.8 1.09± 0.04 3.9 17.3 51.1
0.98 0.95 0.84 0.49 0.87
(n = 30); p
