maximal treadmill versus cycle ergometry testing in … · are the treadmill (tm) and the cycle...

Pediatric Exercise Science, 1995,7,49-60 0 1995 Human Kinetics Publishers, Inc.

Maximal Treadmill Versus Cycle Ergometry Testing in Children: Differences, Reliability,

and Variability of Responses

Kenneth R. Turley, Danette M. Rogers, Kevin M. Harper, Kathleen I. Kujawa, and Jack H. Wilmore

This study was designed to determine the differing cardiorespiratory responses between maximal treadmill ('I'M) and cycle (CY) ergometry, and the reliability and variability of these responses in 46 children 7 to 9 years old (23 boys and 23 girls). Two maximal TM and two maximal CY tests were administered, as well as a body composition assessment. The TM resulted !n a 9.4%, 11.1%, and 10.2% higher maximal oxygen consumption values (V02, ml.kg-'.min-I) than the CY in boys, girls, and the total population, respectjvely. Both the TM and the CY proved to be reliable measures of maximal V02 (ml.kg-'.mid) in both boys and girls, with intraclass correlations ranging from R = .63 to .90. Variability was significantly less (p 5 .05) on the CY (V02 in L-mid) than the TM, 4.4% versus 6.2%, respectively.

The measurement of maximal oxygen consumption ( ~ 0 ~ m a x ) is vital to many research studies, as it is used (a) to estimate and compare the health status of populations, (b) to gauge the effects of fitness intervention programs, (c) to predict relative submaximal workloads for standardized steady-state testing, and (d) a s the criterion standard to validate field tests for assessing physical fitness. The VOzmax values reported in the literature are often obtained on different types of exercise modalities and yet are compared from study to study. The exercise modalities that are most commonly used to measure V02max in children are the treadmill (TM) and the cycle (CY) ergometer (18). In adults the comparison between TM and CY has been studied extensively (4, 9, 10, 12, 16,20, 21, 22), with mean reported differences in V02max ranging from 5 to 12%. In children the TM versus CY comparison, in the same sample, is limited to older children (age 11-14) and only to boys (6, 19), except for Cumming and Langford (7) who tested 5 girls and 5 boys (9-10 years old) and 8 girls and 5 boys (12-13 years old) but did not differentiate by gender. Thus, the need exists to systemati- cally compare V02max and the related cardiorespiratory values obtained on these two types of modalities in young children.

The authors are with the Department of Kinesiology and Health Education at The University of Texas at Austin, Bellmont Hall 222, Austin, TX 78712. Request reprints from J.H. Wilmore.

50 - Turley, Rogers, Harper, Kujawa, and Wilmore

Thus, this study was designed (a) to determine the difference in maximal cardiorespiratory responses between the TM and CY in 7- to 9-year-old boys and girls, and (b) to describe the reliability and variability of these responses.

Subjects and Methods

A11 7- to 9-year-old students from a private elementary school in Austin, Texas, were invited to participate in this study. Forty-six healthy children (23 males and 23 females, 85% participation) and their parents provided written informed consent to participate in the study. The protocol had been previously approved by The University of Texas at Austin Institutional Review Board. Physical characteristics of the subjects are presented in Table 1.

Each subject performed two cycle (CYl and CY2) and two treadmill (TM1 and TM2) tests in random order to determine maximal VO, on each modality. Height, weight, skinfold thicknesses, and leg volume were also measured. All testing was conducted within a 5-week period on the school campus during school and extended-care hours (8:OO a.m. to 5:00 p.m.). Three weeks prior to testing, the study and its procedures were explained to the children, both to alleviate testing anxiety and to encourage participation.

Each exercise test began with height and weight measurements. The child was then fitted with a heart rate (HR) monitor (Polar Vantage XL, Stamford, CT) and was directed to the appropriate exercise modality. Prior to the start of each TM test, the child practiced walking and running for 3 to 5 min. A continuous graded maximal TM (Precor) test was then administered. The protocol began with the subject walking at 3.0 miles per hour (mph) 0% grade for 1 min with a 2.5% increase in grade at both Minutes 2 and 3. At Minute 4 the speed was increased to 5.0 mph, with an additional increase of 0.5 mph at Minute 5. Grade was then increased 2.5% at both Minutes 6 and 7, after which the speed was

Table 1 Subjects' Physical Characteristics

Boys (n = 23) Girls (n = 23) Total (n = 46) Variable M SD M SD M SD

Age (months) Height (cm) Weight (kg) BMI (kg.m2) BSA % fat LBM (kg) LLV (liters)

Note. BMI = body mass index. BSA = body surface area. LBM = lean body mass. LLV = lean leg volume. "n = 22. bn = 45.

Treadmill Versus Cycle Ergometry - 51

increased 0.5 mph each minute until exhaustion. A high-speed protocol was used because pilot work in our laboratory (29) suggested that slower TM speed protocols may not elicit true maximal values in children. The children were not allowed to hold on to the handrails during the TM test. The TM was calibrated three to five times throughout each day.

Maximal CY testing was conducted on a Monark (Model 8 18 E, Sweden) ergometer modified with 140 cm cranks. Once the child was seated on the Monark, the seat height was set and recorded, and the handle bars were adjusted for maximum comfort. CY max ergometer values were attained using a continuous incremental protocol in which the child began pedaling at 65 rpm against zero resistance for the first minute, after which the work rate was increased by 100 kilopond-meters (Kpm.min-I) every minute until exhaustion (36). The rpm was maintained visually, by a digital readout, and by ear, with a metronome, when necessary. The CY was calibrated each morning prior to testing.

Strong verbal encouragement was given to each child throughout each test. Both the TM and the CY ergometer tests were terminated at exhaustion when the child could no longer maintain the work rate. Each exercise test was separated by a minimum of 24 hours, but by not more than 3 days.

Each ~ 0 ~ m a x test was considered acceptable when at least one of the following criteria was met: (a) respiratory exchange ration (RER) of 21.0, or (b) 295% of age-predicted (220 - age) maximal heart rate (HR max). The RER criteria was achieved in 100% of the TM tests and was met in all but one of the CY tests. The HR criteria was reached in 49% of the TM tests and in 45% of the CY tests. Since it has recently been reported that a plateau in VO, is seldom achieved in children (31, 32) or adolescents (26), it was not used as a criterion for attainment of V02max. V02max was considered the mean of the two highest consecutive 20-s readings. The highest ~0~ of the two TM and of the two CY tests were considered the max tests.

Expired gases were collected and analyzed using a SensorMedics 2900 metabolic cart (Yorba Linda, CA), which utilizes a zirconium oxide cell for fractional percentage of expired oxygen (FEO,) determination, an infrared absorp- tion analyzer for fractional percentage of expired carbon dioxide (FECO,) determination, and a mass flow meter for measuring ventilation. The analyzers were calibrated with gases of known concentration both before and after each test.

To further describe the physical characteristics of the children, body composition and leg volume were estimated using anthropometric measurements. Leg volume was determined as described by Jones and Pearson (15). The leg was divided into seven segmented cones, and the circumferences and heights of the cones were recorded and mathematically converted to volumes. The volumes were corrected for fat, estimated from skinfold thicknesses at four sites, to compute lean leg volume (LLV). Total body fat was estimated from the triceps and subscapular skinfold thicknesses, attained with Harpenden calipers, using the Slaughter et al. equations (35). Body surface area (BSA, m2) was calculated using the Haycock et al. formula (1 1).

Significant differences within each variable between Test 1 and Test 2 for each modality, or between modalities, was determined with a paired t test using the p I .05 level, unless otherwise indicated. Test-retest reliability of each modality was determined by intraclass correlation (R) calculated from a one-way ANOVA model and is reported as the reliability of the mean of the tests scores


for each child, (MS, - MSw)/h4Sb, and as the reliability of scores collected on one day, (MS, - MS,)/(MSb + MS,) (5, 25, 36), where MS, = mean square between, and MS, = mean square within subjects.

An intraclass correlation of the mean of the tests scores for each child represents the reliability that results when a measurement is taken more than once, whereas reliability of scores collected on one day represents the reliability that results if a measurement is taken only once. Both types of intraclass correlations will be presented, but only the reliability of the mean of the tests scores will be discussed in the text, as it is what is more commonly reported in the research literature. Intraindividual variability was calculated as the absolute different between Test 1 and Test 2 divided by the mean of both Test 1 and Test 2, resulting in an intraindividual percentage of variation for each child. The average of each of the intraindividual percentage variations provided a mean intraindividual percentage variation (24, 27). Furthermore, intraindividual variability was expressed as the average of the absolute differences between Test 1 and Test 2, and the range of these differences.

Results There were no significant differences between boys and girls in any of the physical characteristics (Table 1). In this sample of children, V02max increased relative to BSA rather than to body weight (28), but in order to compare our results to those in the research literature, V02 will be discussed in absolute terms (Lnmin-I) and relative to body weight (ml.kg-'.min-') and will be only presented in the tables relative to BSA (ml.m-2.min-').

Table 2 lists the maximal values for both modalities in boys, girls, and the total sample. The TM resulted in a higher V0,max (L.min-I and ml-kg-l.min-I)

Table 2 Boys, Girls, and Total Sample Maximal Values

VO, VO* V O ~ Heart rate %% (L.min-') (ml.kg-I) (rnl.m-*.min-') RER (beatsmin-I) (L.min-')

M SD M SD M SD M SD M SD M SD

Boys TM 1.63 0.18" 54.2 6Sa.' 1552 131hb 1.14 0.0.Y 200.3 6.38 65.4 7.9' CY 1.47 0.17' 49.1 6.4' 1401 128a-b 1.12 0.06' 195.5 7.7 60.2 8.4

Girls TM 1.54 0.21a 49.7 4.2" 1433 77" 1.19 0.05 203.0 5.5" 64.1 8.0' CY 1.36 0.18 44.2 5.4 1269 109 1.16 0.05 196.7 7.7 57.3 9.4

Total TM 1.59 0.208 51.9 5.9a 1492 122a 1.17 0.05* 201.6 6.0a 64.7 7.9a CY 1.42 0.18 46.6 6.4 1335 135 1.14 0.06 196.1 7.6 58.7 9.0

Note. RER = Respiratory exchange ratio. TM = treadmill. CY = cycle ergometer. "Significantly different from CY values (p < .01). 'Significantly different from the girls' values ( p I .01). CSignificantly different from the girls' values @ I .05). *Significantly different from CY values (p 5 .05).


values in boys (9.8 and 9.4%), girls (1 1.7 and 11.1%), and the total population (1.07 and 10.2%). The TM resulted in significantly higher max RER, HR, and b values in the total sample. These differences were also present when the boys and girls were analyzed separately, with the exception of RER, which was not significantly different between the two modes of exercise. When making further comparisons between genders, the boys had significantly higher TM ~ 0 ~ r n a x values when it was expressed in .ml-kg-'-min-' @ I .01) but not in L-min-'. Boys had significantly higher CY V02max values regardless of how it was expressed. The girls had significantly higher RER values on both the TM and the CY. Max HR and VE were not significantly different between the genders on either modality.

The mean values for each cardiorespiratory variable for TM 1, TM2, CY 1, and CY2 are listed in Table 3. In the girls and the tofal sample, there were significant differences between TMl and y 2 in V02max (L.min-' and ml.kg-'.min-I), RER, and HR. Furthermore, VE in the girls was significantly higher in TMl. In the boys, RER was significantly higher in TM1. When CY 1 and CY2 were compared, the only significant difference was a higher max HR in CY1 in the girls.

Table 3 Boys, Girls, and Total Sample Treadmill and Cycle Ergometer Values

VO, VO, vo2 Heart rate VE (L-mi&) (ml-kg-I) (ml.m-2.min-') RER (beat.mh-I) (L.min-I)

M SD M SD M SD M SD M SD M SD

Boys (n = 23) TM1 1.59 0.19 52.8 6.5 1509 TM2b 1.58 0.20 52.9 6.4 1509 CYl 1.44 0.16 48.1 6.5 1373 CY2' 1.47 0.18 48.9 6.2 1396

Girls (n = 23) TM1 1.53 0.21d 49.3 4.2* 1423 TM2 1.46 0.22 47.4 4.1 1360 CY1 1.32 0.19 43.0 5.2 1233 CY2 1.33 0.16 43.2 5.5 1244

Total (n = 46) TM1 1.56 O.2Oa 51.1 5.6" 1466 TM2 1.52 0.22 50.1 6.0 1433 CYl 1.38 0.19 45.6 6.3 1303 CY2 1.40 0.18 45.9 6.4 1316

Note. RER = Respiratory exchange ratio. TM1 = Treadmill Test 1; TM2 = Treadmill Test 2; CY1 = Cycle Ergometer Test 1; CY2 = Cycle Ergometer Test 2. aSignificantly different from TM2 @ I .05). bn = 22, one boy did not finish testing. 'n = 21, one boy did not finish testing, and one CY test did not meet VO, criteria. dSignificantly different from TM2 @ 5 .01). eSignificantly different from CY2 @ I .05).


Table 4 Intraclass Correlations and Pearson Product-Moment (PPM) Correlations for Boys, Girls, and Total Sample

vo2 VO, VO, Heart rate VE (L.min-I) (ml.kg-I) (ml.m-2.min-1) RER (beat.min-') (L.min-I)

Single Mult Single Mult Single Mult Single Mult Single Mult Single Mult test test test test test test test test test test test test R R R R R R R R R R R R

Boys (n = 23) TMa .82 .90 CYb .92 .96 PPM .88

Girls (n = 23) TM .88 .94 CY .88 .94 PPM .87

Total (n = 46) TM .86 .92 CY .91 .95 PPM .88

Note. TM = treadmill. CY = cycle ergometer. PPM = relationship between TM and CY max. '% = 22, one boy did not finish testing. bn = 21, one boy did not finish testing, and one CY test did not meet ~ 0 , criteria.

The CY ergometer resulted in higher reliability coefficients than the TM in all variables for boys, girls, and the total sample except in VE for the boys (Table 4). Max values for ~0~ (L.min-I and ml.kg-l.min-I), HR, and VE were highly related between TM and CY (.62-.89), while RER was not as highly related (. 17-.39).

There were no significant differences between the genders in intraindividual variability for any variable on either of the modalities, so values are listed only for the total population (Table 5). The CY resulted in significantly (p I .05) less intraindividual variability (mean percentage and absolute values) in V0,max (L.min-I).

Leg volume of the girls was significantly greater (p I .05) than the boys (4.90 f 1.45 vs. 3.61 f 1 .O1 liters, respectively). Although not significant, LLV was also higher in the girls than in boys (Table 1).

Discussion

The results of this study indicate that exercise to exhaustion on the TM results in significantly higher cardiorespiratory values than on the CY, and that reliable

Table 5 Intraindividual Variability for Cardiorespiratory Values on the Treadmill (TM) and Cycle Ergometer (CY)

V O ~ V O ~ VO, Heart rate VE (L.min-') (mbkg-I) (ml~m-2.min-i) RER (beats.min-') (L.min-I)

M SD Range M SD Range M SD Range M SD Range M SD Range M SD Range

T M a % 6.2 4.5b 0.1-21.1 5.7 4.4 0.0-21.6 6.2 4.5b 0.1-21.1 5.5 4.4 0.0-17.7 1.7 1.5 0.0-8.5 9.5 8.4 0.1-35.8 Absolute 0.09 0.06b 0.00-0.26 2.9 2.3 0.0-11.3 89.0 64.5b 0.9-288.3 0.06 0.05 0.00-0.20 3.4 3.3 0.0-17.0 5.7 4.9 0.1-22.7

+

CYC ii; % 4.4 3.6 0.0-15.3 4.5 3.7 0.2-14.7 4.4 3.6 0.0-15.3 4.1 3.5 0.0-14.5 1.8 1.3 0.5-6.2 8.4 6.0 0.2-29.5 Absolute 0.06 0.05 0.00-0.24 2.0 1.7 0.1-6.6 57.5 45.2 0.0-205.6 0.05 0.04 0.00-0.17 3.6 2.5 1.0-12.0 4.9 3.7 0.1-17.5 %

< g Note. N = 46. RER = respiratory exchange ratio. c

V)

an = 45, one boy did not finish testing. bSignificantly different from CY values ( p 5 .05). 'n = 44, one boy did not finish testing and one CY o test did not meet V O ~ criteria. 5

(D


results are attained during maximal testing on either the TM or CY in 7- to 9- year-old children. However, the CY resulted in slightly more reliable and less variable values. Furthermore, the children generally preferred the CY test over the TM test.

This study resulted in a -9% difference between 'I'M and CY ~ 0 , m a x values in these boys, which is consistent with the 8% difference reported in 11- to 14-year-old boys by Boileau et al. (6) and Macek et al. (19): In addition, the present study demonstrated that there is an 11% difference in V02max between the and CY ergometer in young girls. Lastly, a comparison of the upright CY V02max values and TM VOzmax values of Cumming and Langford (7) resulted in a 10.5% difference in ~0~ when 9- to 13-year-old boys and girls were grouped together, which is similar to the 10% difference observed in our total sample.

Furthermore, in a study often cited for TM versus CY differences, Ikai and Kitagawa (13) reported an 8 to 19% difference in both boys' and girls' (age groups ranging from 8 to 27 years old) CY V02max values, which they collected, when compared to TM V02max values reported in a previous study (14). In another study that makes a similar comparison, -strong et al. (3) reported a 9 to 12% difference between TM and CY peak V02 values in 11- to 15-year- old boys and girls when tested on either the TM or CY ergometer (none of the children were tested on both modalities). These differences in V02max between the TM and CY in children of differing ages are similar to the 5 to 12% difference reported in adult males (4, 9, 10, 12, 16, 20, 21, 22) and females (16).

VE rnax was significantly higher (p I -01) on the TM in boys, girls, and the total population, which is in contrast to the results of Boileau et al. (6), who reported no difference. There were no gender differences in VE rnax on either modality, which agrees with the results of Davies et al. (8).

HR rnax was significantly (p I .01) higher on the TM compared to the rnax values on the CY in boys (200 vs. 196 beats-min-I), girls (203 vs. 198 beats-min-I), and the total population (202 vs. 196 beats-min-I), but was not significantly different between the genders. Our HR rnax values match the "practi- cal guidelines" set forth by Rowland (30) of a HR of 200+ on the TM and 195+ on the CY as indicators of rnax values. Boileau et al. (6) also saw a significantly (p I .01) higher HR on the TM in boys (194 vs. 186 beats-min-I). Furthermore, although Armstrong et al. (3) did not report the significance of their HR differences, TM HR peak (200 and 201 beats.min-') was consistently higher than CY HR peak (195 and 195 beats-mid) in both boys and girls, respectively. Also, Cumming and Langford (7) reported significantly (p I .05) higher maximal HR during TM versus CY testing in boys and girls grouped together. Lastly, Davies et al. (8) did not see any gender differences in rnax HR on the CY in children younger than age 13.

The results of our RER rnax values are less consistent. RER was not significantly different between the TM and CY when the genders were separated, but when they were combined as a group, the TM RER of 1.17 was significantly higher (p I .05) than the CY RER of 1.14. This is in contrast to the results of Boileau et al. (6) who found TM RER (1.04) to be significantly 0,s -01) lower than CY RER (1.1 1). Furthermore, Rowland (30) reported on a number of studies that found higher RER values during CY than during TM maximal testing in


which influences maximal testing in children (18,33). The children in this study were highly motivated, which may have caused them to push harder than the children in other studies. Furthermore, the higher RER on the TM vefsus the CY may haye been due to more of the children achieving a classic V02max (plateau in V02) on the TM.

Both the TM and CY proved to be reliable measures of ~ 0 m a x in both genders and the total sample, with the CY being slightly more reliable. Although there were some significant diierences in VOzmax between TM1 and TM2 (Table 3) the reliability coefficients were quite high (Table 4): R = .90 and .90 in the boys, R = .94 and -77 in the girls, and R = .92 and .89 in the total sample for V O ~ in L-mir-' and ml-kg-'.rninmin', respectively. With CY there were no significant differences in vo2max between CYl and CY2. Furthermore, the reliability coefficients in CY VO, were consistently higher: R = .96 and -96 in the boys, R = :94 and .93 in the girls, and R = -95 and .96 in the total population (Table 4) for V02 in L-min-' and ml-kg-'-min-', respectively. Our high reliability coefficients on the CY are similar to the interclass correlation coefficients of r = .95 and .88 for V02 (L-min-' and ml.kg-'-min-') reported by Boileau et al. (6). In contrast, Boileau et al (6) reported as high or higher reliability on the TM with interclass correlations between treadmill tests of r = -97 and .87 for \jo2 (Lmmin-' and ml-kg-'-min-I).

Our higher reliability on the CY compared to the TM may be due to a higher motivational level in our children, as discussed earlier, causing them to continue longer on the CY in spite of the local muscular discomfort common to CY testing. The lower reliability on the TM versus the CY may be further due to the TM being a weight-dependent activity. As the children near exhaustion, their gait and peripheral movement become abnormal as they attempt to continue despite the onset of fatigue. As they become fatigued, they must work harder to maintain their upright posture, as well as continue running, resulting in a less reliable response. On the CY, although fatigue occurs, the children do not have to support the mass of their body, and thus, the abnormal movement is attenuated. In addition, the children did not seem to give as great an effort during TM2 versus TM1, this is supported by the trend for TM1 max values (Table 3) to be higher than TM2, which would further contribute to the lower reliability on the 'I'M.

Intraindividual variability, although low on both modalities, was significantly ( p I .05) lower on the CY versus the in V02max (Lmin-I) and consistently lower, although not significantly, in VOzmax (ml-kg-'.min-') and RER max (Table 5). The 4.4 to 4.5% CY intraindividual variation in CY V02max in our sample is similar to the 4.4% (coefficient of variation, defined as intraindividual variation) reported by Boileau et al. (6). Our TM V02max intraindividual variation ranged from 5.7 to 6.2%, which also is similar to the 5.3% (coefficient of variation) reported by Boileau et al. (6). The higher variability on the TM is likely due to the same factors that contributed to the lower reliability of the TM discussed in the preceding section.

The high correlation between TM V02max and CY vo2rnax (Lamin-', ml.kg-'.min-I) values-r = .88 and 39 , r = .87 and 34 , and r = .88 and .89 in the boys, girls, and total population (Table 4), respectively-indicates that rank order on both exercise modalities is highly maintained. A high correlation between TM and CY V02max (L.min-' and ml-kg-'mid) was also reported by Boileau

58 - Turley, Rogers, Harper, Kujawa, and Wilrnore

et al. (6) (r = .95 and r = 34). This implies that when classifying children by fitness category, based on maximal VO,, the TM and CY modalities will result in a similar rank order.

Significant gender differences in young children's Vo2max values have been reported on both the CY (1, 2, 8) and the TM (2, 17) with boys' values significantly higher. We observed a significantly higher relative Vo2max (mi-kg-I-min-') in the boys on both the TM and CY, and a significantly higher absolute ~ 0 , m a x (L-min-') on the CY. It has been suggested that the gender difference in VOzmax may be related to a larger muscle mass in boys (1, 3, 8, 18). Davies et al. (8) reported that the gender difference on the CY was eliminated when V O ~ was expressed relative to LLV. Our results do not support this finding. Boys7 VO~.LLV-' was significantly higher (p I .01) than the girls' value. In this group of children, LLV was higher in the girls, while V0,max (L.min-') was higher in the boys; thus, the significant difference between the genders in CY V02max was not related to LLV.

Other suggested mechanisms for explaining the difference in ~ 0 , m a x between boys and girls are higher hemoglobin (3, 18), physical activity levels (1, 3, 18), and cardiac output in boys. Armstrong et al. (3) reported significantly higher (p < .05) hemoglobin concentrations in boys than girls by 9 years of age. Miyarnura and Honda (23) reported higher maximal cardiac outputs in 9- to 10- year-old boys than in girls of the same age. Assuming no significant gender difference in max HR (2, 17), stroke volume in boys would be higher. The higher stroke volume may be the result of a larger heart volume in boys than girls, as has been reported in young children (34,37). Furthermore, significant correlations between V02max and heart volume were reported (34). Hence, although we did not measure hemoglobin, physical activity, or cardiac output, our higher VOzmax values in the boys on both the TM and CY are likely related to these factors.

It is interesting to notice that in the girls and the total sample, maximal values for VO,, RER, and HR were significantly higher in TM1 versus TM2, and in the girls, VE rnax was also significantly higher on TM1. In the boys, RER max was significantly higher on TM1 versus TM2. The significantly higher TM1 values, consistently lower TM reliability coefficients, consistently higher TM intraindividual variability, lack of significant differences in ~ 0 , m a x between CYl and CY2, and the children's preference for the CY over the TM during maximal testing, suggests that the CY ergometer may be more appropriate for max testing in children of this age. In addition, the CY ergometry does not require an accommodation period. Hence, in both the clinical and research setting where the number of required visits per subject must be kept to a minimum, the CY ergometer may be the best suited modality for maximal testing.

In conclusion, TM V0,max is 9 to 11% higher than CY VOzmax in both boys and girls 7 to 9 years of age, which is similar to what has been reported in both older children and adults. Both the TM and the CY proved to be reliable measures of maximal cardiorespiratory values, but the CY resulted in consistently higher reliability and consistently less variability. The lower reliability and higher variability on the TM, combined with the fact that in the girls and the total population TM1 was significantly higher than TM2, suggests that in this age group the CY is a more reliable measure of maximal cardiorespiratory variables. Furthermore, the children generally preferred the CY over the TM during maximal

Treadmill Versus Cycle Ergometty - 59

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Acknowledgments We gratefully thank Libby Weed, Kelsie Turley, Becky Orick, and Jodie Coyle

for allowing us to test the children in their classes. We also thank the children, their parents, and the other teachers, faculty, and staff from Brentwood Christian School for their enthusiastic participation in this study.

maximal treadmill versus cycle ergometry testing in … · are the treadmill (tm) and the cycle...

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