Christian Vobejda

Introduction: Prolonged time trials proved capable of precisely estimating anaerobic threshold. However, time trial studies in recreational cyclists are missing. The aim of the present study was to evaluate accuracy and viability of constant power threshold, which is the highest power output constantly maintainable over time, for estimating maximal lactate steady state in recreational athletes. Methods: A total of 25 recreational athletes participated in the study of whom 22 (11 female, 11 male) conducted all constant load time trials required for determining constant power threshold 30 min and 45 min, which is the highest power output constantly maintainable over 30 min and 45 min, respectively. Maximal lactate steady state was assessed subsequently from blood samples taken every 5 min during the time trials. Results: Constant power threshold over 45 min (175.5 ± 49.6 W) almost matched power output at maximal lactate steady state (176.4 ± 50.5 W), whereas constant power threshold over 30 min (181.4 ± 51.4 W) was marginally higher (P = 0.007, d = 0.74). Interrelations between maximal lactate steady state and constant power threshold 30 min and constant power threshold 45 min were very close (R² = 0.99, SEE = 8.9 W, Percentage SEE (%SEE) = 5.1%, P < 0.001 and R² = 0.99, SEE = 10.0 W, %SEE = 5.7%, P < 0.001, respectively). Conclusions: Determination of constant power threshold is a straining but viable and precise alternative for recreational cyclists to estimate power output at maximal lactate steady state and thus maximal sustainable oxidative metabolic rate.

The aim of the present study was to improve and confirm a time trial (TT) based method for determining anaerobic threshold (AnT) requiring minimal equipment. Eighteen participants underwent three to five all-out TTs for at the most 60 min. Velocity of the TTs was adapted in 0.1 or 0.2 m*s-1 steps until maximal velocity maintainable for at least 45 min (V(max45)) was identified. Exercise was interrupted every 5 min in order to take blood samples. After the participants had finished their last TT blood lactate concentration (BLC) was determined to identify maximal lactate steady state (MLSS). Velocity, BLC and heart rate (HR) at the TTs giving MLSS (TTMLSS) and giving V(max45) (TTV(max45)) were almost identical (3.45 ± 0.31 m*s-1 vs. 3.44 ± 0.31 m*s-1, 4.46 ± 1.28 mmol*L-1 vs. 4.52 ± 1.28 mmol*L-1, 177 ± 9.8 bpm vs. 178 ± 9.4 bpm). Coefficient of correlation (R) and standard error of estimate (SEE) between velocity at MLSS (VMLSS) and V(max45) were 0.96 and 0.09 m*s-1, respectively, indicating a very close relationship. Agreement between VMLSS and V(max45) was also very high. At VMLSS cardiovascular drift (CVD) was 8.4 ± 2.6 bpm from the 10th to 30th min. At V(max45) CVD was 7.9±2.8 bpm from the 10th to 30th min and 11.2 ± 3.8 bpm from the 10th to 45th min. Determination of V(max45) is a manageable, cost-saving and precise method for predicting velocity and CVD at MLSS in healthy, ambitious and at least moderately trained runners.

The aim of the present study was to investigate the accuracy of the maximal constant heart rate method for predicting anaerobic threshold (AnT) in running. This method only requires a common heart rate (HR) monitor and is based on the identification of the maximal constant HR maintainable for 30 min (HR_MC). HR_MC, 4-mmol threshold, and maximal lactate steady state (MLSS) were determined in 31 probands. 17 probands underwent an additional MLSS retest within 2 weeks. The correlation between HR at MLSS and at MLSS retest was very close (r = 0.807; SEE = 5.25 beats · min^-1; p < 0.001). So were the correlations between HR at 4-mmol threshold and MLSS (r = 0.844; SEE = 6.43 beats · min^-1; p < 0.001) and between HR_MC and HR at MLSS (r = 0.820; SEE = 6.73 beats · min^-1; p < 0.001). Mean velocities at maximum constant HR trials and MLSS (r = 0.895; SEE = 0.185 m · s^-1; p < 0.001) as well as 4-mmol threshold and MLSS (r = 0.899; SEE = 0.186 m · s^-1; p < 0.001) were highly correlated. In conclusion, data presented in this study confirm that the determination of HR_MC is a manageable method giving a highly accurate estimation of both HR and velocity at MLSS in running.

The purpose of this study was to verify the hypothesis that the postexercise increase (PEI) of plasma free fatty acid (FFA) concentrations after cessation of exercise is a suitable qualitative indicator for the FFA utilisation during the foregoing exercise. Fourteen, 17 and 23 healthy subjects participated in 3 test series performing several prolonged exercise protocols (PEP) on a bicycle ergometer. During and after cessation of the PEP heart frequency, lactate and FFA were measured. Fasting resulted in an increase of PEI (90%, p<0.05) and the synergistic use of upper body muscles during cycling caused a significant rise of PEI compared to "regular" cycling (39%, p<0.01). Increasing workload step by step produced continuously rising PEI (p<0.05), only from 42% to 50% of maximal workload PEI decreased by 17% (p=n.s.). The results support the hypothesis that PEI is a suitable qualitative indicator for FFA utilisation during a foregoing exercise. Furthermore the results indicate that there is a maximum of FFA utilisation in the legs at 40% of maximum workload during cycling and that the upper body muscles contribute substantially to total body FFA turnover at high inten-sities, an aspect to which possibly too little attention has been paid to when quantifying FFA turnover during cycling.