Issue 31 Spring 2012 - Bases

Exercise and atrial fibrillation
Dr Gary Brickley provides an overview of this condition, its impact of exercise
tolerance, and considerations for exercise.
What is atrial fibrillation?
Atrial fibrillation (AF) is a common but largely
under-recognised cardiac arrhythmia, which is
demonstrated in Figure 1 as an increase in the
number of P waves relative to the number of QRS
complexes. In many cases this can mean that the
atria are contracting over 150 times per minute
whilst the ventricles contract around 60 times per
minute.
Figure 1. A trial fibrillation as demonstrated
from an ECG
Approximately 100,000 people in the UK
have AF. It is often associated with a poor lifestyle,
alcoholism, a poor diet and obesity. In some
cases individuals have no symptoms (Lone AF),
but many experience shortness of breath, poor
exercise tolerance, dizzy spells and palpitations.
When presented with these symptoms an ECG
may determine the presence of AF. A follow up
echocardiogram is normally carried out. AF may
then be treated initially with medication such as
amiodarone, beta blockers and ACE inhibitors.
Later this may involve surgery including AF
ablation.
Aside from being common in the elderly
population, AF is also common in highly-trained
endurance athletes (Mont, Elosua & Brugada,
2009; Turagam, Velagapundi & Kocheril, 2012);
however, the mechanisms behind this are poorly
understood. Nevertheless, as for the differences
in left ventricular hypertrophy in the diseased
and athletic heart, the causes of AF are probably
different in athletes compared to typical older
adults. Causes in athletes might include increased
vagal tone, inflammation and
fluid shifts, whereas in the
elderly it is usually
due to hypertension,
“We as practitioners
working with
patients and
athletes need to
be confident in
detecting AF, as well
as ensuring referral
to the appropriate
cardiology team. ”
valvular disease or previous myocardial infarction.
The prognosis is also worse for non-athletes;
these have a relatively high risk of stroke and
heart failure.
Exercise tolerance in people with AF
We recently presented a paper at the Australian
Conference of Sports Science and Medicine
in Perth Australia (Brickley et al., 2012) where
we were interested in the differences in
cardiorespiratory fitness in AF patients versus
healthy controls. We exercised both groups to
volitional exhaustion on a cycle ergometer and
measured expired air. We also assessed quality
of life using the SF-36 questionnaire (Ware et al.,
1993). Markers of aerobic fitness were generally
lower in the AF group (see Table 1), as were the
physical functioning domains of quality of life.
The ability to exercise at high intensity is
often related to deterioration in aerobic fitness.
The associated symptoms of shortness of breath
during exercise, dizziness on exertion and poor
heart rate regulation certainly lead to a reduction
in aerobic fitness in AF patients. Treatment with
medication and surgery may alleviate some of
these symptoms and allow for an improvement in
exercise tolerance and quality of life.
Exercise considerations in people with AF
Is it dangerous to exercise with AF?
Although the risk of a cardiac event is greater
in those with heart disease and irregular
rhythms, the risk for exercising with AF is poorly
understood. Typically this patient may be given a
cocktail of medication to slow their heart rate
down and manage their rhythm. Once exercise is
added to this cocktail it is important to monitor
not only the symptoms during exercise but other
parameters such as blood pressure and the
incidence of ectopic beats. Exercise stress testing
using ECGs is initially recommended to those
who have been diagnosed. However, the European
Society of Cardiology guidelines for exercise
suggest that heart rate should be controlled
between 90-115 bpm during moderate exercise
(Camm et al., 2010). There is evidence to suggest
that limiting physical activity can reduce the
number of incidents of AF in those with recent
diagnosis. However, as Mont, Elosua and Brugada
(2009) point out, it is often hard for those who
regularly exercise to follow this advice.
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10 The Sport and Exercise Scientist n Issue 31 n Spring 2012 n www.bases.org.uk