Thanks to the numerous positive effects of exercise (1-5) and its steadily growing importance in
exercise oncology, exercise is recommended to all cancer survivors (CS) (3, 6-9). The existing
oncology exercise guidelines are based on the assumption that intensity specifications can be
transferred from healthy individuals to CS. However, it was shown that cardio-metabolic
parameters used for intensity prescription may be altered in CS due to cancer treatment (10,
11). So-called second-generation trials are demanded which compare the effects of different
training prescriptions aiming at elaborating the optimal exercise prescription for CS (12).
Consequently, before conducting the demanded studies, a fundamental question must first be
clarified: “Is my selected dosage actually what it claims to be when I prescribe a certain intensity
for a cancer survivor?”. This was the leading question of this dissertation; Without its final
clarification no progress can be made towards individualized training prescription. A precise
intensity prescription is a prerequisite for eliciting the greatest possible training effects without
provoking training overload. The TOP study was the first to systematically investigate whether
currently used methods of intensity prescription are reliable for its use in CS.
The main questions were (I) whether maximal oxygen uptake (VO2max) as the major parameter
used for intensity prescription, is actually attained by CS during a cardiopulmonary exercise test
(CPET), (II) whether three different established methods for intensity prescription for endurance
exercise are equally suitable for targeting a specific intensity zone, and (III) whether commonly
used methods of intensity testing and prescription in resistance exercise are also valid in CS. The
TOP study was designed to answer these research questions; The results were discussed in three
manuscripts which constitute the main body of this dissertation.
I. Manuscript 1 (chapter 5) targets the question whether CS attain their true VO2max in a CPET.
We analyzed data from 75 CS who underwent a supramaximal verification test to confirm
the attainment of VO2max. We found that VO2max was not underestimated in the CPET on the
group level, yet one third of CS did not attain their true VO2max. We concluded that the
verification test appears feasible and beneficial for distinguishing between patients who
attained their true VO2max and those who did not.
II. In manuscript 2 (chapter 6) we evaluated whether threshold concepts might be useful
submaximal alternatives to %VO2max in terms of meeting the vigorous intensity zone. We
compared physiological and psychological responses of three training sessions defined by
Abstract
III
three different prescription methods: blood lactate (bLa) thresholds, ventilatory thresholds,
and %VO2max as reference. The data showed that all intensity prescription methods met the
targeted intensity zone on average, however the session prescribed via bLa thresholds
provoked the most homogeneous bLa responses. Furthermore, not all CS were able to
complete the training sessions, we therefore concluded that slightly lower percentages
should be chosen to improve durability of the training sessions.
III. Manuscript 3 (chapter 7) focused on whether different maximum strength tests yield
comparable results and are therefore applicable interchangeably. Maximal strength values
derived from two indirect strength testing methods (h1-RM after Brzycki (13) and Epley
(14)) were compared to one direct method of 1-RM determination, all performed at six
different resistance machines. The results vary between the different methods with the
occurrence of both, over- and underestimation of patients’ strength performance. This
should be considered when training intensities are to be described based on maximal
strength values, and when comparing maximal strength data between studies using
different testing procedures. Moreover, we aimed to investigate the prediction accuracy for
targeting specific intensity zones in resistance exercise in CS, i.e., whether the achieved
number of repetitions (NOR) corresponding to specific values of %1-RM/h1-RM were
accurately predicted. We found in part extreme deviations between the targeted NOR and
the NOR actually performed. We conclude that the prediction accuracy of all test
procedures seems to be very poor for all tested strength training machines for the chosen
intensities. The use of %1-RM/h1-RM for intensity prescription is therefore questionable for
this population.
Our results demonstrate that currently used methods of exercise testing and prescription seem
to have only limited applicability in CS. The overall conclusion for endurance exercise is that
threshold concepts seem to be suitable alternatives to %VO2max for intensity prescription, yet
bLa thresholds should be favored if a defined metabolic strain is intended as this method evokes
the most homogeneous bLa response between individuals. Furthermore, a verification test
seems necessary to ensure VO2max attainment, if percentages of VO2max are used for intensity
prescription, or if the effect of a training intervention is evaluated based on changes of VO2max.
Regarding resistance exercise, commonly used methods for testing are not safe (1-RM) or
imprecise (h1-RM) which is also true when %1-RM/h1-RM is used for intensity prescription.
Abstract
IV
Directly approaching specified intensities might be an alternative method for intensity
prescription in resistance training.
A phenomenon that connects all three manuscripts is that the individual data show in part
extreme interindividual variations which tell different stories than the group means. Therefore,
special attention should be paid to interindividual variability when prescribing exercise for CS.
The choice of methods should fit the goals and possibilities of the patients. Subsequently,
maximum accuracy is warranted in the context of studies, whereas in practice, more inaccuracies
can be accepted, and the methods should be chosen accordingly. Independent of the setting,
our results demonstrate that it is important not to blindly trust on calculated exercise intensity
specifications but to consider them as orientation. For this, it is important to closely monitor the
patients for signs of over- or underload, to ensure maximum safety and adequate training
stimulus at the same time.
There will and can never be one method that fits all. People are individuals and training should
be prescribed accordingly. The results presented in this dissertation contribute important
insights about the accuracy of different exercise testing as well as prescription methods, and
further advance the field of personalized exercise oncology. However, they only represent a first
step in the still largely unresearched field of exercise prescription in CS and point to a need for
further research
