ERGONOMICS, 1990, VOL. 33, No.8, 1027-1042
The relation between cycling time to exhaustion and anaerobic threshold S. AUNOLA, E. ALANEN, J. MARNIEMl The Rehabilitation Research Centre of the Social Insurance Institution, Peltolantie 3, SF-20720 Turku 72, Finland and H. RUSKO Department of Biology of Physical Activity, University of Jyviiskylii, Jyviiskylii, Finland Keywords: Anaerobic threshold; Blood lactate; Endurance; Exponential function; Fibre types; Prolonged exercise
This study investigated whether the anaerobic threshold (AnT) could be used to predict prolonged work capacity measured as cycling time to exhaustion (=endurance time) and which factors, in addition to relative exercise intensity, could explain variation in endurance time. Theoretical exercise intensities corresponding to certain endurance times were also calculated. The hyperbolic and exponential functions between cyclingtime and relative work rate (WR[%]), as well as between cyling time and relative oxygen uptake (V0 2 [ %] ) were fitted to the pooled data (n = 45) of 17 subjects. The WR(%) and V0 2 (%) were expressed as a percentage of the subject's own AnT- and maximum -values, At WR corresponding to AnT (i.e., 70%of WRmu ) an average subject could cycle60 min according to both AnT- or maximum-related exponential function. When prediction was done for an endurance time of 4 h, the AnT-related exponential function gave 2'9%-units (= II W or -0'15 0 2 1. min -') lower intensity level (51%ofWR mu ) than the maximumrelated function (54% of WRmu ) ' The WR(%) alone explained 54% and 70% of the variation in endurance time of the AnT-related and maximum-related exponential functions, respectively. Muscle fibre composition and initial blood lactate or relative muscle glycogen depletion (change in muscle glycogen as percentage) increased significantly the explanatory power of these models. The differences between the observed and expected exercise times correlated with blood lactate accumulation (r= -0'42; p
40
Q
40
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20 '.0.73
0 70
20
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0 85
100
115
70
'30
85
WR AnT{%)
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120
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w 100
60
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115
140 C
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100 ~02 AnT(%)
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0 50
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70 WR Max (% )
80
90
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60
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90
~02 Max ('!o)
Figure 1. Exponential dependence ofendurancetime(asdependentvariable) on work rate and oxygen uptake as a percentage of A-B: anaerobic threshold (AnT) and C-D: maximum (Max).
3_ Results In a 2 min incremental exercise test, the AnT was achieved at V0 2 of 37·9 rnl- kg - 1 - min - 1 and at a venous blood lactate of 3·2 mmol-l-l, on the average. The mean V0 2 max was 53·5 mI· kg-I ·min -I and the maximal venous blood lactate was 11·4mmol-I" 1 (table 1).In general, there were no marked changes during the test series in blood Hb, Hct or S-prot at rest. In the prolonged exercise tests, there were no significant differences between values of resting blood lactate, RPE at exhaustion, fibre types or initial muscle glycogen stores in four intensity classes (table 2).WR(%), V0 2 (%), endurance time, and blood lactate at exhaustion differed significantly (p
The relation between cycling time to exhaustion and anaerobic threshold S. AUNOLA, E. ALANEN, J. MARNIEMl The Rehabilitation Research Centre of the Social Insurance Institution, Peltolantie 3, SF-20720 Turku 72, Finland and H. RUSKO Department of Biology of Physical Activity, University of Jyviiskylii, Jyviiskylii, Finland Keywords: Anaerobic threshold; Blood lactate; Endurance; Exponential function; Fibre types; Prolonged exercise
This study investigated whether the anaerobic threshold (AnT) could be used to predict prolonged work capacity measured as cycling time to exhaustion (=endurance time) and which factors, in addition to relative exercise intensity, could explain variation in endurance time. Theoretical exercise intensities corresponding to certain endurance times were also calculated. The hyperbolic and exponential functions between cyclingtime and relative work rate (WR[%]), as well as between cyling time and relative oxygen uptake (V0 2 [ %] ) were fitted to the pooled data (n = 45) of 17 subjects. The WR(%) and V0 2 (%) were expressed as a percentage of the subject's own AnT- and maximum -values, At WR corresponding to AnT (i.e., 70%of WRmu ) an average subject could cycle60 min according to both AnT- or maximum-related exponential function. When prediction was done for an endurance time of 4 h, the AnT-related exponential function gave 2'9%-units (= II W or -0'15 0 2 1. min -') lower intensity level (51%ofWR mu ) than the maximumrelated function (54% of WRmu ) ' The WR(%) alone explained 54% and 70% of the variation in endurance time of the AnT-related and maximum-related exponential functions, respectively. Muscle fibre composition and initial blood lactate or relative muscle glycogen depletion (change in muscle glycogen as percentage) increased significantly the explanatory power of these models. The differences between the observed and expected exercise times correlated with blood lactate accumulation (r= -0'42; p
40
Q
40
Z
w
20 '.0.73
0 70
20
'.0.66
0 85
100
115
70
'30
85
WR AnT{%)
140 c
120
C
z ~
w 100
60
;::
Q
Z W
w
80
z ~
60
Q
40
U
U
::::>
D
120
::i
::i
w
'30
§.
w 100 60
115
140 C
§.
;::
100 ~02 AnT(%)
::::>
40
Z
w
20
20
,.0.76 0
0 50
60
70 WR Max (% )
80
90
50
60
70
80
90
~02 Max ('!o)
Figure 1. Exponential dependence ofendurancetime(asdependentvariable) on work rate and oxygen uptake as a percentage of A-B: anaerobic threshold (AnT) and C-D: maximum (Max).
3_ Results In a 2 min incremental exercise test, the AnT was achieved at V0 2 of 37·9 rnl- kg - 1 - min - 1 and at a venous blood lactate of 3·2 mmol-l-l, on the average. The mean V0 2 max was 53·5 mI· kg-I ·min -I and the maximal venous blood lactate was 11·4mmol-I" 1 (table 1).In general, there were no marked changes during the test series in blood Hb, Hct or S-prot at rest. In the prolonged exercise tests, there were no significant differences between values of resting blood lactate, RPE at exhaustion, fibre types or initial muscle glycogen stores in four intensity classes (table 2).WR(%), V0 2 (%), endurance time, and blood lactate at exhaustion differed significantly (p
