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Predictive validity of ventilatory and lactate thresholds for cycling time trial performance
Author(s) -
Amann Markus,
Subudhi Andrew W.,
Foster Carl
Publication year - 2006
Publication title -
scandinavian journal of medicine and science in sports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.575
H-Index - 115
eISSN - 1600-0838
pISSN - 0905-7188
DOI - 10.1111/j.1600-0838.2004.00424.x
Subject(s) - anaerobic exercise , cycling , lactate threshold , respiratory exchange ratio , ventilatory threshold , zoology , time trial , linear regression , medicine , carbon dioxide , respiratory system , regression analysis , mathematics , vo2 max , blood lactate , chemistry , heart rate , statistics , biology , physical therapy , archaeology , blood pressure , history , organic chemistry
Purpose: To determine which laboratory measurement best predicts 40 km cycling time‐trial (TT) performance. Methods: Fifteen male cyclists performed lactate‐threshold (LT), ventilatory‐threshold (VT), 5 km and 40 km TT. Key variables of interest were Watts at thresholds. For VT determination we used: breakpoint of ventilatory equivalent of oxygen (VE/VO 2 ); breakpoint of ventilatory equivalent of carbon dioxide (VE/VCO 2 ); V‐slope; respiratory exchange ratio (RER)=1 and 0.95. For LT we used Stegmann's individual anaerobic threshold; the stage preceding the second 0.5 mmol L −1 increase (Baldari); 4 mmol L −1 ; 1 mmol L −1 increase in 3 min; the stage preceding the first 1 mmol L −1 increase as criterion methods (<1 mmol). Analyses also included peak power during the incremental threshold tests (MaxVT watts , MaxLT watts ) and 5 km performance (5K avgwatts ). Results: Regression analyses between VT variables and 40K avgwatts were significant for V‐slope ( r 2 =0.63), VE/VO 2 ( r 2 =0.64), RER 0.95 ( r 2 =0.53), RER 1 ( r 2 =0.57), and MaxVT watts ( r 2 =0.65). Regressions between LT variables and 40K avgwatts were significant for Baldari ( r 2 =0.52), 4 mmol L −1 ( r 2 =0.36), <1 mmol ( r 2 =0.35), Keul ( r 2 =0.34), and MaxLT watts ( r 2 =0.51). Regressions between 5K variables and 40K avgwatts were significant for 5K avgwatts ( r 2 =0.58). Paired t ‐tests between these variables and the 40K avgwatts indicated that absolute power outputs at VE/VO 2 ( P =0.33), RER 0.95 ( P =0.93), and 4 mmol L −1 ( P =0.39) were not significantly different from 40K avgwatts . Conclusion: We conclude that VT‐based variables are generally superior to LT variables relative to predicting 40K avgwatts , the simplest of several valid measures appears to be VE/VO 2 .