Weber (2003) described a specific test protocol for cycling to assess the maximal glycolytic rate (Vlamax). This protocol was specifically designed for an SRM ergometer and consisted of a 15s isokinetic seated sprint (120 rpm). The ergometer settings were adjusted based on body mass.
Until now, it remains unclear to what extend the ergometer settings of a cyclus II ergometer (one of the most used high-end ergometers in research and athlete monitoring) impact on the power profile and blood lactate response of a similar sprint test.
Secondly, VO2, VCO2, pH and blood lactate kinetics during the maximal endurance efforts of 3, 6 and 12 min duration will be investigated.
Twelve subjects volunteered to participate in this study. To minimize fatigue and optimize glycogen stores; subjects were instructed to refrain from exhaustive physical exercise during 24 hours before each experimental trial and to consume a carbohydrate rich meal 2 hours before each testday. At the first visit to the laboratory, bodyweight, height and body composition (Seca mBCA 525, Hamburg, Germany) were assessed.
The subjects performed 8 cycling tests in 3 days in a semi-randomized order (table 1). The tests included maximal sprint efforts, a ramp test, and maximal time-trial efforts of 3-, 6- and 12-minute duration. During all tests subjects were verbally encouraged. As VO2max type efforts deplete phosphocreatine (PCr) stores in the exercising muscle and might therefore negatively impact on subsequent exercise performance, a minimum of 30-minute rest was provided to allow for adequate recovery. This was controlled by measuring capillary blood lactate concentration (BLC) before each test. Subjects with BLC > 2 mmol/l extended their rest until BLC dropped below 2 mmol/l.
The subjects performed five 20-second sprints to assess the peak power output (PPO), average power output (APO), the alactic time (Talac) defined as the time when a 3% drop in maximal power was observed and the maximal glycolytic rate (VLamax). Only before the first sprint test the subject performed a 6-second sprint to familiarize with the test procedures and -equipment. During the sprints subjects had to maintain a seated position. Each sprint was preceded by a 10-minute warming up at 1,5 W/kg body weight followed by a 2-minute passive rest to minimize the aerobic energy contribution during the subsequent sprint. A capillary blood lactate sample was taken from the earlobe and analyzed before the sprint to measure baseline BLC (EKF Biosen C-line, Barleben, Germany) and pH (ABL90Flex Plus, Radiometer). In case BLC > 2 mmol/l was observed, the recovery period was extended by 3 minutes and this procedure was repeated until BLC were < 2 mmol/l. After each sprint capillary blood samples were taken at 1-minute intervals to determine BLC and pH. This procedure was continued until the maximum BLC had been detected. VLamax was calculated by the delta lactate over delta time (Weber 2003) and using the PPD application in the INSCYD software (Salenstein, Switzerland). As maximal sprint power is depended on the cycling cadence, the ergometer was set in isokinetic mode with a fixed cadence of 120 RPM and a virtual gear of 52×11. It was demonstrated that initial load influences the power output. Therefore 4 different settings for initial load and starting cadence were included in the experimental protocol (table 2).
The subjects performed 3-, 6 and 12-minute time trial efforts to calculate critical power, MLSS, VO2max and VLamax using the PPD protocol in the INSCYD software. A ramp test was performed to assess VO2max. The subjects were allowed to use their preferred cadence during all endurance tests. All tests were performed in a seated position. Before each test a 10-minute warming up at 1,5W/kg body weight was performed. Prior to each test BLC and pH was measured. If BLC > 2 mmol/l, the recovery period was extended by 3 min and this procedure was repeated until BLC < 2 mmol/l. During the endurance test, oxygen consumption (VO2) and carbon dioxide output (VCO2) was monitored using a breath-by-breath metabolic cart. After each test capillary blood samples were taken at 1-minute intervals to determine BLC and pH. This procedure was continued until the maximum BLC had been detected.
The ramp test started at 100 watts and the workload increased with 30-second increments of 20 Watt until volitional exhaustion. A maximum effort was established when a minimum of 2 of the following criteria were met:
The reliability of the sprint test protocol will be evaluated by Bland-Altman plots and intraclass correlations. The key metrics of the 3 sprint protocols will be compared (peak power output, time to reach peak power output, mean power output, pre and post lactate concentrations, pre and post pH values) as well as the calculation of VLamax.
VO2, VCO2, pH and blood lactate kinetics during the maximal endurance efforts of 3, 6 and 12 min duration will be investigated.
The INSCYD PPD protocol will be applied to compare calculated VO2max and VLamax with the measured values.
Modelling fat and carbohydrate use under interval and stochastic load patterns, where steady-state assumptions break down. An INSCYD research project.
Separating muscular from pulmonary oxygen uptake kinetics with a computer model of the cardiopulmonary system. An INSCYD research project with Prof. Dr. Aaron Baggish and CREPS Aquitaine.
VO₂max, VLamax, FatMax, thresholds, fuel use and training zones, from a single test in the lab, in the field or fully remote.
