Sensitivity and the effect of centrally acting exercise performance modifiers in time trial and constant work rate test protocols.

Submaximal exercise tests such as the constant work rate (CWR) test protocols
are frequently used to evaluate changes in exercise variables after
interventions. In these CWR protocols on a cycle ergometer work rate is
constant (usually 75 * 85% of peak work rate measured at an incremental
exercise test), and subjects are asked to exercise as long as they can. Time to
exhaustion is measured and used to evaluate intervention effects. These CWR
protocols are called open- ended test protocols. In open- ended test protocols
there is no clearly defined ending point of the test as the total work
performed in this test depends on the exercise capacity of the subjects. In
contrast, in closed-ended test protocols an ending point of the test is clearly
defined as the total work performed or total time is determined in advance. In
time trial (TT) tests, the exercise capacity of the subject determines the time
that is needed to complete the total work. The reproducibility of closed- ended
TT performance tests is much higher than open- ended performance test protocols
in healthy subjects. Exercise performance is regulated by a series of complex
mechanisms to insure that humans always exercise with reserve and terminate the
exercise bout before there is a catastrophic failure of homeostasis . These
mechanisms do influence exercise performance differently in closed-ended en
open-ended tests. The poor reproducibility of CWR protocols has been attributed
to the fact that CWR protocols do not have a clearly defined ending point and
psychological factors (i.e. motivation, monotony, and boredom), that might
influence performance are more pronounced in these tests than in closed-ended
test in which the ending point of the test is known. However, little is known
about the influence of the open- ended and closed- ended character of the tests
on exercise performance.

Some researchers have argued that the large error of measurement in CWR tests
(coefficients of variation 10*30%) would mask changes in endurance performance
of a few percentage points, which are important for competitive athletes and
which are detectible in time trials (coefficients of variation 1*3%). However,
the changes in time to exhaustion resulting from experimental interventions are
also much greater than changes in time-trial performance and might compensate
for the difference in error of measurement. For example, the positive effect of
prior high-intensity exercise on endurance performance is 30*60% when measured
with a constant-power test to exhaustion and 2*3% when measured with a time
trial.
While this finding is good evidence that time to exhaustion (CWR) is a reliable
measure of endurance performance, we found only one study comparing the
sensitivity of the constant work rate test and time trial test. In this study
of Amann et al., the time to exhaustion protocol had a similar sensitivity to
that of time-trial time for the effects of arterial oxygenation in conditions
of normoxia, hypoxia, and hyperoxia and presumably other factors affecting
endurance performance. Sensitivity is an important characteristic of a good
performance test and might determine which of these two tests is more
appropriate for quantifying changes in endurance performance arising from
experimental interventions. More investigations are needed to extend these
findings of Annan et al. to interventions other than changes in arterial
oxygenation such as the effect of a training intervention. Therefore, the
purpose of this study is to evaluate the sensitivity and the contribution of
centrally acting exercise performance modifiers in open-ended (CWR) and
closed-ended test (TT) protocols.

The objective of this study is to evaluate the differences in exercise
performance in healthy subjects, caused by the open-ended (CWR) en closed-ended
(TT) character of the exercise test when cycled at the same absolute work rate.
In addition, the sensitivity of the closed-ended time trial (TT) cycle exercise
performance test and the open-ended constant work rate test (CWR) for the
effect of a training intervention in healthy subjects will be examined. The
sensitivity of the TT test will be compared with the CWR test and the results
for the training effects measured by the Lamberts and Lambert Submaximal Cycle
Test (LSCT).

The purpose of this study is to evaluate the differences in exercise
performance in healthy subjects, caused by the open-ended (CWR) en closed-ended
(TT) character of the exercise test and to examine the sensitivity of a TT and
the CWR in healthy subjects. One way to express the sensitivity of the TT and
the CWR test is through a signal to noise ratio or a sensitivity index. This
can be achieved by the means of calculating the effect size by the ratio of the
change in performance and the within-subject CV. Therefore the sensitivity of
the TT and the CWR can be evaluated by calculating the TT & CWR test delta
performance / subject CV. For this purpose, the protocol has two groups, the TT
group (in which the sensitivity of the TT will be determined) and the CWR group
(in which the sensitivity of the CWR will be determined). These test protocols
only differ in the number of times the TT and the CWR test is performed
(determination of the CV of the test). Therefore the study design is described
for the TT group (Table 1). In this test protocol, each subject performs a
maximal incremental exercise test - until exhaustion - after a standard
breakfast. In this test VO2max and Wmax will be determined. The TT test will be
executed at least 48 hrs after the maximal incremental exercise test at
70%Wmax. In the time-trial protocol the electromagnetically ergometer is set in
the linear mode; work rates will increase with increasing pedalling rate and
subjects will be asked to perform a certain amount of work (approximately 30
min cycling) as fast as possible. Time to complete the target amount of work is
the measure of performance. During and after the TT test, subjects will receive
no information about time. The CWR test will be executed at least 48 hrs after
the TT test at the same individual intensity (mean work rate) as in the TT test
at the individually preferred pedal frequency. This test will be executed three
times in order to calculate the CV of the TT test. After this series of TT
test, subjects perform a CWR test. In the CWR test, time to exhaustion is the
measure of performance. Another 48 hrs after the CWR test, subjects perform the
LSCT. This test is used as a reference test of training status. This LSCT test
consists of three stages of different workloads coinciding with fixed
predetermined heart rates. Heart rate recovery (HRR) will measured after the
last stage of the test. Parameters associated with performance such as power,
cadence and rating of perceived exertion (RPE) will be measured during all
tests, and all test will be performed at the same time of day. The differences
in exercise performance time between the TT and the CWR performed at the same
mean work rate will be examined.
To evaluate the sensitivity of the test for the effects of a training
intervention, each test-protocol (TT, CWR, LSCT) will be repeated after a set
period of four weeks of an individually trainingprogramme (Table 1). This
training programme will not be evaluated in this study, and is solely used to
assess the sensitivity of the TT, the CWR for the effects of a training
intervention, and is therefore no *intervention*. The sensitivity of TT and the
CWR will be assessed by evaluation of the changes in exercise variables before
and after a four-week individual exercise-training programme and related to
results of the LSCT.

The risk and burden in this study is deemed minimal as the exercise tests
(maximal incremental exercise test, TT, CWR and the LSCT) used in the study are
frequently used to examine the effects of exercise programmes in healthy
subjects. Moreover, the individual four week training programme consists of
submaximal cycling exercise and the subjects are relatively well trained they
will be recruited form the Fontys University of Applied Sciences in Eindhoven
offers bachelor degree programs in Sports & education, Sports & Wellness and
Sports & Leisure in the Netherlands. In addition, subjects were previously
screened were recently medically examined in a Sport Medical Advise Centre in
The Netherlands. The maximal incremental exercise test, TT, CWR and the LSCT
have proven to be safe and the use of these tests to evaluate aerobic capacity
is widely accepted. These risk and burden of these exercise tests are deemed
minimal for these active healthy subjects. A researcher is present during these
tests and there is a medical doctor available during the maximal exercise tests.
The PAR-Q questionnaire (the physical activity readiness questionnaire) will be
used to determine the safety or possible risk of exercise. The burden does not
include extra visits to the University of Applied Sciences in Eindhoven during
the 7 weeks of the study as all tests and training sessions will be planned
according to the course schedule of the institute. The total duration; each
training session visit will not exceed 60 minutes; a maximal exercise test
(once; 20 min each visit), time trial test and constant work rate test (both
twice: 30 minutes). Therefore the extra burden is for participants are: 8 tests
(20-30 minutes) and the exercise training twice a week during four weeks (60
minutes each visit). Risks are not more than expected from regular submaximal
training. Benefits for the subjects are improvement of exercise performance and
insight into the different tests protocols used in this study, as these tests
are also teached in the regular bachelor programme.

In this study, subjects can always contact the main investigator or independent
medical doctor at any time during the course of the study should they have
questions or comments regarding protocol adherence tor any other questions
related to the study. Subjects in this study will receive an invitation letter
with a written explanation of the aims and procedures of the study and a verbal
explanation; Attached to the invitation letter, an explanation about the
insurance will be provided. Subjects can contact investigator Willem Gosens
(PhD) and the independent medical doctor, during and after the study. The
research data will be analysed, described and kept by Mr. Willem Gosens (PhD
student). Subjects can end their participation at any time without explanation.