SubMaximal exercise testing to assess the AnaeRobic Threshold in nEuromusculaR diseases

A primary goal of rehabilitation programs in individuals with neuromuscular
diseases (NMD) is to promote physical fitness to break the vicious cycle of
inactivity that they often encounter. At present, clear guidelines to
individually prescribe, monitor and evaluate aerobic training programs are
lacking, hampering effective application in neuromuscular rehabilitation.

The anaerobic threshold (AT), a submaximal direct marker of aerobic fitness, is
used for exercise intensity prescription in the healthy population and other
chronic diseases, and may also be useful in NMD. The AT is used as an intensity
target which distinguishes between low- and high intensity exercise zones,
enabling individuals to exercise in tailored heart rate zones. It is shown that
it is possible to determine the AT through submaximal exercise testing in
individuals with post-polio syndrome (a slowly progressive NMD), making it a
promising tool for use in daily clinical practice. However, the reliability of
this assessment within post-polio syndrome is unknown, and it is not yet
determined if the AT can also be identified through submaximal exercise testing
in other slowly progressive NMDs.

A major disadvantage of conventional assessment of the AT is that it is a
complex and lengthy procedure requiring expensive respiratory gas analysis
equipment, and is not readily available in all healthcare settings. Therefore,
the next innovative step is to develop a predictive model to easily determine
the AT in NMD, i.e. without the use of expensive gas analysis equipment.

Proposed methods for indirect determination of the AT are based on responses
during exercise of heart rate, respiration, RPE, arterial oxyhemoglobin
saturation and a combination of heart rate and blood pressure. However, these
methods are mostly examined in other populations than NMD. Moreover, using a
combination of these methods might increase the accuracy of the AT assessment.

Objectives:

(1) To determine whether the AT can be identified in individuals with slowly
progressive NMD through submaximal exercise testing with respiratory gas
analysis.

(2) To determine the reliability of the AT assessment in individuals with
slowly progressive NMD through submaximal exercise testing with respiratory gas
analysis.

(3) To develop a predictive model using easy to measure variables to indirectly
assess the AT through submaximal exercise testing without respiratory gas
analysis in individuals with slowly progressive NMD.

A cross sectional study will be conducted at the Department of Rehabilitation
of the Amsterdam UMC, location AMC.

Participants will complete three testing days. On the first and second testing
day, two submaximal exercise tests will be performed, one with and one without
respiratory gas analysis. On the third testing day, a maximal exercise test
will be executed. Testing days will be separated by a minimum of three days.

All patients will be asked to visit the study center on 3 separate days. A
total of 5 exercise tests will be performed during these visits. During the
first and second testing day, two submaximal exercise tests will be performed,
with 60 minutes of rest in between tests. During the third testing day, a
maximal exercise test will be performed. These visits will take approximately 2
hours per visit.

To check for contra-indications for physical exercise, a physician will
thoroughly examine the participants according to the guidelines by the American
College of Sports Medicine (ACSM). The Amsterdam UMC, location AMC, is
experienced in conducting exercise tests in patients with different
neuromuscular diseases. Therefore, the occurrence of medical events is
considered minimal.