The Accuracy of the Critical Velocity Test for Predicting Time to Exhaustion during Treadmill Running M. L. Pepper, T J. Housh, G. 0. Johnson Center for Youth Fitness and Sports Research, University of Nebraska-Lincoln
M L. Pepper, T. I Housh, and G. 0. Johnson, The Accuracy of the Critical Velocity Test for Predicting Time to Exhaustion during Treadmill Running. Tnt J Sports Med, Vol 13,No2,pp 121—124,1992.
anaerobic work capacity (AWC), respectively (1, 9, Il).
Theoretically, CP and AWC represent the maximal powerloading that can be maintained without exhaustion and the
Accepted: June 30, 1991
The purpose of this invetigation was to determine the accuracy of the critical velocity (CV) test for predicting time to exhaustion (time limit = TL) during tread-
mill running. Ten adult males ( SD of age
calculated as the product of the imposed powerloading (p) and TL [WL = p(TL)]. The relationship between WL and TL for the various powerloadings (Fig. 1) was found to be highly linear and, therefore, could be described by the equation for a straight line: WL = a + b(TL). The slope "b" and y-intercept "a" of this line have been termed the critical power (CP) and
23 2
years) volunteered to perform a maximal treadmill test, a CV test, and five exhaustive treadmill runs at 70%, 85 Vu, 100%, 115% and 130% of CV for the determination of actual TL. Related t-tests revealed significant (p < 0.05) differences between the predicted and actual TL values for velocities equal to 100 and 130% of CV. The correlations between predicted and actual TL values for velocities above
work capacity associated with stored energy sources within the muscle, respectively (1, 3, 9, 11). An equation for predicting the TL for any imposed powerloading can be derived by solving for TL from the two equations for WL:
WL = p(TL) and WL = a + b(TL) p(TL) = a+b(TL) a = p(TL) — b(TL) a=TL(p—b) TL = a/(p—b)
minutes). At 100% of CV, the subjects maintained the run-
Therefore, by substituting AWC for "a" and CF for "b", the equation becomes TL = AWC/(p — CP). This equation describes the hyperbolic relationship between p and TL which
fling pace for an average of 16.43 6.08 minutes
has a asymptote equal to CP (Fig. 1).
CV ranged from r=0.957 to 0.980 (SEE=0.28—0.82 (range = 9.96—31.90 minutes) while, at 85% ofCV, 8 of the 10 subjects were able to maintain the running pace for 60 minutes. These findings did not support the validity of the CV test for predicting the actual TL during treadmill running and indicated that, in 20% of the cases, CV overestimated the running velocity that could be maintained for 60 minutes by greater than 15%.
p
TL =
Key words cP—..
Critical velocity, anaerobic running capacity
AWC/(p-CP)
I
I
I
TL
WL
Introduction
Monod and Scherrer (9) developed a technique to define the amount of work a synergic muscle group could perform before being exhausted and the conditions of a fatigueless task. This technique involved a series of exhaustive
workbouts at various powerloadings from which the total amount of work performed (work limit WL) and the time to exhaustion (time limit = TL) were determined. The WL was
= Aoaerob,c Work Capacily b = Critical Power
a' TL
Fig. 1 Schematic diagram of the relationships for the imposed power output (p) versus time limit (TL) and work limit (WL) versus IL
lnt.J.SportsMed. 13(1992)121—124 GeorgThieme Verlag StuttgartNew York
to determine critical power {CP) and anaerobic work capacity (AWC).
Downloaded by: Universite Laval. Copyrighted material.
Abstract
122 mt. J. Sports Med. 13 (1992) V
M. L, Pepper, T J. Housh, G. 0. Johnson Table 1
Descriptive characteristics of the subjects (n = 10)
Characteristics
TL ARC/(v-CV) cv—
I
I
TL
Range
1.
23±2
2.
175.5±5.0 74.2±8.4 13.43±2.04
19—27 167.6—182.9 61.2—84.8 10.43—17.85
200.8±62.6 54.4±6.6
98.3—299.0 47.7—70.9
Age jyrs) Height (cm) 3. Weight (kg) 4. 5.
Critical Velocity (kmh)
6
VO2max. (ml/kgmin1)
Anaerobic Running Capacity (m)
TO
was to determine the accuracy of the equation TL = ARC/(v — CV) from the CV test for predicting the actual TL during treadmill running.
Materials and Methods TL
Fig. 2 Schematic diagram of the relationships for treadmill velocity (v) versus time limit (IL) and total distance (ID) versus IL to determine critical velocity (CV) and anaerobic running capacity (ARC).
Moritani et a!. (11) applied the CP concept to cycle ergometry and suggested that for powerloadings less
than CP, the work rate could be continued "almost indefinitely". For powerloadings greater than CP, however, the stored energy sources are utilized at a predictable rate and exhaustion occurs when the energy stores are depleted. Thus, it
was suggested that the TL for any imposed powerloading during cycle ergometry could be predicted from the results of the CP test using the equation TL AWC/(p — CP). Housh et a!. (3) reported, however, that CP overestimated the work rate that could be maintained for 60 minutes by a mean of approximately 17%.
McDowell et al. (7) proposed a treadmill analog of the CP test called the critical velocity (CV) test. For this test, a series of exhaustive treadmill runs were performed at different velocities (v) from which the total distance run [TD = v(TL)] and TL for each run were determined. In this situation, the TD for the CV test is analogous to WL from the CP test. When TD was plotted as a function of TL, a highly linear 0.98 to 1.00) relationship [TD = a+b(TL)] was found, (r2 with the slope "b" and the y-intercept "a" termed the CV and
anaerobic running capacity (ARC), respectively (Fig. 2).
McDowell et al. (7) found a high correlation (r = 0.94) and no significant mean difference (p> 0.05) for CV vs the running velocity corresponding to the ventilatory anaerobic threshold. These findings suggested that the CV could be maintained for an extended period of time without exhaustion. Furthermore, theoretically, the TL for any running velocity can be predicted from the hyperbolic relationship between v and TL using the equation TL = ARC/(v — CV) (Fig. 2). This equation is derived by solving for TL from the two equations for TD:
TD = a + b(TL) and TD = v(TL) TL = a/(v — b) By substituting ARC for "a" and CV for "b", the equation becomes TL = ARC/(v — CV). The purpose of this investigation
Ten adult males (Table 1) volunteered as subjects for this investigation and gave informed consent prior to any testing. Maxima! oxygen consumption (VO2max) was determined using a continuous incremental treadmill test to exhaustion. Following a three-minute walking warm-up at
4.83 kmh the treadmill velocity was set at 6.44 kmh and 0% grade. Each three minutes the speed was increased
1.61 km-hup to 14.49 km-h When 14.49 kmh1was reached, there was no further increase in speed, and work intensity was increased by raising the treadmill grade 2% every
three minutes until voluntary exhaustion. The subjects breathed through a Hans-Rudolph valve, with gas volumes (VE) and concentrations (FEO2 and FECO2) measured using a standard open circuit gas analysis technique and a calibrated MMC Horizon Metabolic Measurement Cart (Sensor Medics corporation, Anaheim, CA). The test was considered maximal
if there was a plateau of V02 with increasing workloads and/or an R value > 1.15 (8). Heart rate values were recorded throughout the test using a UNIQ CIC Heartwatch system (6). The CV test was performed using a slight modi-
fication of the protocol described by Hughson et a!. (5). The subject completed four randomly ordered treadmill runs to ex-
haustion at velocities ranging from 12.88 to 21.74 kmh. The workbouts were separated by at least 24 hours. Prior to each run, the subject practiced getting on and off of the treadmill at the velocity associated with the workbout to familiarize themselves with the running speed. Timing for each workbout began when the subject's hands left the handrails and was terminated when the subject grasped the handrails to signal exhaustion. Strong verbal encouragement was given throughout each run, with the TL and subject's heart rate recorded immediately at the end of each workbout. The TD was calculated as the product of the running velocity (v) and TL: TD = v(TL). The CV and ARC were defined as the slope and y-intercept of the relationship between TD and TL (Fig. 2). The TL estimated from the equation TL = ARC/(v — CV) was considered the predicted TL.
To determine the accuracy of the equation TL ARC/(v — CV), the subjects performed five randomly ordered treadmill runs at velocities approximately equal to 70%, 85%, 100%, 115% and 130% of CV. The TL values for
=
these workbouts were considered the actual TL. The trials
Downloaded by: Universite Laval. Copyrighted material.
al
liii. J. Sports Med. 13(1992) 123
The Accuracy of the Critical Velocity Test Table 2 Comparison between the predicted and actual TL values
(kmh )
Actual TL (minutes)
Predicted TL (minutes)
9.29± 1.50 11.19±1.74
60.00** 55.12±10.29
60.00** 60.00**
—0.15
1.4
13.25 2.04
60.00* *
— 22.65*
114.9±3.2
15.15±2.41 17.30±2.67
16.43 6.08 7.16±2.84
Percent of CV
Velocity
70.4±2.1 84.8±1.5 100.3 130.1
7.18±3.00 3.15± 1.34
3.43± 1.40
SEE
t
—0.68
r
(minutes)
0.957* 0.980*
0.82 0.28
*p
M L. Pepper, T. I Housh, and G. 0. Johnson, The Accuracy of the Critical Velocity Test for Predicting Time to Exhaustion during Treadmill Running. Tnt J Sports Med, Vol 13,No2,pp 121—124,1992.
anaerobic work capacity (AWC), respectively (1, 9, Il).
Theoretically, CP and AWC represent the maximal powerloading that can be maintained without exhaustion and the
Accepted: June 30, 1991
The purpose of this invetigation was to determine the accuracy of the critical velocity (CV) test for predicting time to exhaustion (time limit = TL) during tread-
mill running. Ten adult males ( SD of age
calculated as the product of the imposed powerloading (p) and TL [WL = p(TL)]. The relationship between WL and TL for the various powerloadings (Fig. 1) was found to be highly linear and, therefore, could be described by the equation for a straight line: WL = a + b(TL). The slope "b" and y-intercept "a" of this line have been termed the critical power (CP) and
23 2
years) volunteered to perform a maximal treadmill test, a CV test, and five exhaustive treadmill runs at 70%, 85 Vu, 100%, 115% and 130% of CV for the determination of actual TL. Related t-tests revealed significant (p < 0.05) differences between the predicted and actual TL values for velocities equal to 100 and 130% of CV. The correlations between predicted and actual TL values for velocities above
work capacity associated with stored energy sources within the muscle, respectively (1, 3, 9, 11). An equation for predicting the TL for any imposed powerloading can be derived by solving for TL from the two equations for WL:
WL = p(TL) and WL = a + b(TL) p(TL) = a+b(TL) a = p(TL) — b(TL) a=TL(p—b) TL = a/(p—b)
minutes). At 100% of CV, the subjects maintained the run-
Therefore, by substituting AWC for "a" and CF for "b", the equation becomes TL = AWC/(p — CP). This equation describes the hyperbolic relationship between p and TL which
fling pace for an average of 16.43 6.08 minutes
has a asymptote equal to CP (Fig. 1).
CV ranged from r=0.957 to 0.980 (SEE=0.28—0.82 (range = 9.96—31.90 minutes) while, at 85% ofCV, 8 of the 10 subjects were able to maintain the running pace for 60 minutes. These findings did not support the validity of the CV test for predicting the actual TL during treadmill running and indicated that, in 20% of the cases, CV overestimated the running velocity that could be maintained for 60 minutes by greater than 15%.
p
TL =
Key words cP—..
Critical velocity, anaerobic running capacity
AWC/(p-CP)
I
I
I
TL
WL
Introduction
Monod and Scherrer (9) developed a technique to define the amount of work a synergic muscle group could perform before being exhausted and the conditions of a fatigueless task. This technique involved a series of exhaustive
workbouts at various powerloadings from which the total amount of work performed (work limit WL) and the time to exhaustion (time limit = TL) were determined. The WL was
= Aoaerob,c Work Capacily b = Critical Power
a' TL
Fig. 1 Schematic diagram of the relationships for the imposed power output (p) versus time limit (TL) and work limit (WL) versus IL
lnt.J.SportsMed. 13(1992)121—124 GeorgThieme Verlag StuttgartNew York
to determine critical power {CP) and anaerobic work capacity (AWC).
Downloaded by: Universite Laval. Copyrighted material.
Abstract
122 mt. J. Sports Med. 13 (1992) V
M. L, Pepper, T J. Housh, G. 0. Johnson Table 1
Descriptive characteristics of the subjects (n = 10)
Characteristics
TL ARC/(v-CV) cv—
I
I
TL
Range
1.
23±2
2.
175.5±5.0 74.2±8.4 13.43±2.04
19—27 167.6—182.9 61.2—84.8 10.43—17.85
200.8±62.6 54.4±6.6
98.3—299.0 47.7—70.9
Age jyrs) Height (cm) 3. Weight (kg) 4. 5.
Critical Velocity (kmh)
6
VO2max. (ml/kgmin1)
Anaerobic Running Capacity (m)
TO
was to determine the accuracy of the equation TL = ARC/(v — CV) from the CV test for predicting the actual TL during treadmill running.
Materials and Methods TL
Fig. 2 Schematic diagram of the relationships for treadmill velocity (v) versus time limit (IL) and total distance (ID) versus IL to determine critical velocity (CV) and anaerobic running capacity (ARC).
Moritani et a!. (11) applied the CP concept to cycle ergometry and suggested that for powerloadings less
than CP, the work rate could be continued "almost indefinitely". For powerloadings greater than CP, however, the stored energy sources are utilized at a predictable rate and exhaustion occurs when the energy stores are depleted. Thus, it
was suggested that the TL for any imposed powerloading during cycle ergometry could be predicted from the results of the CP test using the equation TL AWC/(p — CP). Housh et a!. (3) reported, however, that CP overestimated the work rate that could be maintained for 60 minutes by a mean of approximately 17%.
McDowell et al. (7) proposed a treadmill analog of the CP test called the critical velocity (CV) test. For this test, a series of exhaustive treadmill runs were performed at different velocities (v) from which the total distance run [TD = v(TL)] and TL for each run were determined. In this situation, the TD for the CV test is analogous to WL from the CP test. When TD was plotted as a function of TL, a highly linear 0.98 to 1.00) relationship [TD = a+b(TL)] was found, (r2 with the slope "b" and the y-intercept "a" termed the CV and
anaerobic running capacity (ARC), respectively (Fig. 2).
McDowell et al. (7) found a high correlation (r = 0.94) and no significant mean difference (p> 0.05) for CV vs the running velocity corresponding to the ventilatory anaerobic threshold. These findings suggested that the CV could be maintained for an extended period of time without exhaustion. Furthermore, theoretically, the TL for any running velocity can be predicted from the hyperbolic relationship between v and TL using the equation TL = ARC/(v — CV) (Fig. 2). This equation is derived by solving for TL from the two equations for TD:
TD = a + b(TL) and TD = v(TL) TL = a/(v — b) By substituting ARC for "a" and CV for "b", the equation becomes TL = ARC/(v — CV). The purpose of this investigation
Ten adult males (Table 1) volunteered as subjects for this investigation and gave informed consent prior to any testing. Maxima! oxygen consumption (VO2max) was determined using a continuous incremental treadmill test to exhaustion. Following a three-minute walking warm-up at
4.83 kmh the treadmill velocity was set at 6.44 kmh and 0% grade. Each three minutes the speed was increased
1.61 km-hup to 14.49 km-h When 14.49 kmh1was reached, there was no further increase in speed, and work intensity was increased by raising the treadmill grade 2% every
three minutes until voluntary exhaustion. The subjects breathed through a Hans-Rudolph valve, with gas volumes (VE) and concentrations (FEO2 and FECO2) measured using a standard open circuit gas analysis technique and a calibrated MMC Horizon Metabolic Measurement Cart (Sensor Medics corporation, Anaheim, CA). The test was considered maximal
if there was a plateau of V02 with increasing workloads and/or an R value > 1.15 (8). Heart rate values were recorded throughout the test using a UNIQ CIC Heartwatch system (6). The CV test was performed using a slight modi-
fication of the protocol described by Hughson et a!. (5). The subject completed four randomly ordered treadmill runs to ex-
haustion at velocities ranging from 12.88 to 21.74 kmh. The workbouts were separated by at least 24 hours. Prior to each run, the subject practiced getting on and off of the treadmill at the velocity associated with the workbout to familiarize themselves with the running speed. Timing for each workbout began when the subject's hands left the handrails and was terminated when the subject grasped the handrails to signal exhaustion. Strong verbal encouragement was given throughout each run, with the TL and subject's heart rate recorded immediately at the end of each workbout. The TD was calculated as the product of the running velocity (v) and TL: TD = v(TL). The CV and ARC were defined as the slope and y-intercept of the relationship between TD and TL (Fig. 2). The TL estimated from the equation TL = ARC/(v — CV) was considered the predicted TL.
To determine the accuracy of the equation TL ARC/(v — CV), the subjects performed five randomly ordered treadmill runs at velocities approximately equal to 70%, 85%, 100%, 115% and 130% of CV. The TL values for
=
these workbouts were considered the actual TL. The trials
Downloaded by: Universite Laval. Copyrighted material.
al
liii. J. Sports Med. 13(1992) 123
The Accuracy of the Critical Velocity Test Table 2 Comparison between the predicted and actual TL values
(kmh )
Actual TL (minutes)
Predicted TL (minutes)
9.29± 1.50 11.19±1.74
60.00** 55.12±10.29
60.00** 60.00**
—0.15
1.4
13.25 2.04
60.00* *
— 22.65*
114.9±3.2
15.15±2.41 17.30±2.67
16.43 6.08 7.16±2.84
Percent of CV
Velocity
70.4±2.1 84.8±1.5 100.3 130.1
7.18±3.00 3.15± 1.34
3.43± 1.40
SEE
t
—0.68
r
(minutes)
0.957* 0.980*
0.82 0.28
*p
