Study done by: Leanne Heede, Joe Hickson, E.E. Noreen


Historically, it has been challenging to replicate endurance performance measured in a laboratory setting. One common solution has been an indoor time trial (TT) using the subjects’ bicycle placed onto a trainer, which applies resistance to the rear wheel. A TT is the completion of a given distance in the least amount of time. This traditional method presents technical complications and does not provide the subjects with any external motivational stimuli. Despite these drawbacks this method has shown good test-retest reliability (1-4).

The Velotron Pro bicycle ergometer uses virtual 3D interactive software that simulates a virtual cyclist riding outdoors. The subjects’ power output (watts) is used by the software to determine instantaneous speed of the computer simulated cyclist. The software provides the option of using a pacer to give the subject a virtual cyclist to race against. As a result of the software, the Velotron Pro provides the rider with continuous feedback that is not available using a standard trainer. The Velotron Pro is a fully adjusted bicycle ergometer that uses an electronic brake as opposed to a bike placed on a roller system which relies on friction between the tire and roller. This removes one of the common technical problems seen with the traditional method used for indoor TTs.

Unlike TT that did not use a pacer which either found no improvement over time or an improvement from TT1-TT2 and not TT2-TT3 (1-4), a previous study from this lab using the Velotron Pro with a pacer suggested an improvement in TT performance with each subsequent trial.

Our goal of this study was to determine the test-retest reliability of three consecutive repeated indoor time trials using the Velotron Pro bicycle ergometer without any pacer.

We performed the study using seven trained competitive cyclists (ages 39 +/- 10 years). We performed three time trials on an 8 mile course which was at a 4% incline. Each trial was completed within 2-7 days under the same standard conditions. On the fourth visit, the cyclists body compositing was assessed using the Bodpod and the cyclists VO2 ma

x was measured using a metabolic cart.

The subjects performed a routine 15 minute warmup which was the same each time. The velotron ergometer was calibrated according to the instructions. For each time tiral that was performed, the finishing time, average watts, average heart rate, and average RPMs were recorded. The data that we recorded was analyzed using a repeated measures ANOVA, CV, ICC, and SEM.

Table 1 shows the averages for the data that was recorded during each time trial. Table 2 shows the reliability of the testing that we performed. This helped us determine is the cyclists improved over each trial along with other things. Graph 1 shows the differences in time between the three different trials that were performed.

The data that we obtained from this study shows that there was almost a significant difference between the first and second time trials. The difference between the second and third time trials were not significant. This can be seen in Table 2. This data suggests that removing a pacer decreases the liklihood of continual improvement with each consecutive trial performed. By looking at Table 2, we can suggest that the pacer may unfluence the finishing time while having little or no effect on the test-retest reliability. This is consistent with other studies that have been performed.


  1. Jensen K. and Johansen L. Reproducibility and Validity of Physiological Parameters Measured in Cyclists Riding on Racing Bikes Placed on a Stationary Magnetic Brake. Scand J Med Sci Sports 8: 1-6, 1998.
  2. Palmer G.S., Dennis S.C., Noakes T.D., and Hawley J.A. Assessment of the Reproducibility of Performance Testing on an Air-Braked Cycle Ergometer. Int J Sports Med 17: 293-298, 1996.
  3. Smith M.F., Davidson R.C., Balmer J., and Bird S.R. Reliability of Mean Power Recorded During Indoor and Outdoor Self-Paced 40 km Cycling Time-Trials. Int J Sports Med 22: 270-274, 2001.
  4. Sporer, B.C. and D.C. McKenzie. Reproducibility of a Laboratory Based 20-km Time Trial Evaluation in Competitive Cyclists Using
  5. Bike Picture:
  6. Rider Picture:

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1 comment:

ultraswede said...

Is it the reliability of the ergometer or more indirect the effectiveness of the pacer as a training gem that is studied?

I suspect the improvement from Ride 1 to Ride 2 has to do with the rider getting accustomed to the electronic gearing, but it is not clear if You monitored this behavior issue. That would account for the Ride 3 result of no improvement.