The impact of heart failure on exercise-induced cardiac fatigue: an explorative study

Walking represents moderate-intensity exercise which can be performed for
several hours. This makes (prolonged) walking exercise an effective strategy to
improve physical fitness and to attenuate the development / progression of
cardiovascular diseases. Previous studies indicated that a physical active
lifestyle can improve longevity and reduce the risk for future cardiovascular
events in various clinical populations. Accordingly, walking exercise is
frequently prescribed by physicians, resulting in the participation of patients
with cardiovascular diseases (e.g. heart failure, myocardial infarction,
coronary artery disease, etc.) in walking events like the Nijmegen Four Days
Marches.

Prolonged exercise is known to cause an acute, but transient, impairment in
cardiac function in healthy young populations. Previous studies reported
reductions in ejection fraction and systolic/diastolic dysfunction following
endurance exercise, which is referred to as *cardiac fatigue*. Whether these
exercise-induced responses are also present in heart failure patients, who
demonstrate an a priori impaired cardiac function, is currently unknown.

Primary objective: To compare the impact of a single day of prolonged walking
exercise on cardiac function and biomarker responses between heart failure
patients and their age- and sex-matched controls.

Secondary objective: To compare the impact of 1-day versus multiple days of
prolonged walking exercise on cardiac function and biomarker responses in heart
failure patients and age- and sex-matched controls.

An observational study in which the cardiac function will be examined before
and immediately after the 1st and 3rd day of the Nijmegen Four Days Marches in
20 participants. Blood samples for cardiac biomarker analysis will be obtained
at baseline, and after day 1, 2, 3 and 4 of the Nijmegen Four Days Marches.

Walking is not associated with serious health risks. Actually, regular physical
activity such as walking exercise protects against cardiovascular disease/risk.
Furthermore, our primary outcome measures relate to non-invasive measurement of
cardiac function. Our secondary outcome measures will be determined from a
venous blood sample (i.e. cardiac biomarkers). This procedure is associated
with a minor risk for haemorrhage (5%).