1. The purpose of the present study was to
analyse the incidence and type of coordination
between breathing rhythm and leg movements
during running and to assess the effect of
co-ordination on the running efficiency, as well
as to compare the results with those found
during cycling.
2. The experiments were carried out on
thirty-four untrained volunteers exercising at
two work loads (60 and 80% of subject's physical
work capacity 170) on a treadmill. In addition
nineteen of the subjects exercised at the same
two work loads on a bicycle ergometer. The
subjects were running at both work loads in
three different modes in randomized order: with
normal arra movements, without arm movements and
with breathing paced by an acoustic signal which
was triggered by the leg movement.
3. Respiratory variables, oxygen uptake and
leg movements were continuously recorded and
evaluated on-line. The degree of co-ordination
was expressed as a percentage of inspirations
and/or expirations starting in the same phase of
the step or pedalling cycle.
4. The average degree of co-ordination was
higher during running (up to 40%) than during
cycling (about 20%) during both work loads. The
difference in the degree of co-ordination
between running and cycling is probably not due
to the lack of arm movements during cycling
since the degree of co-ordination during running
with and without arm movements was the
same.
5. The degree of co-ordination during
running increased slightly but not significantly
with increasing work load and could be increased
significantly by paced breathing.
6. The co-ordination between breathing and
running rhythms occurred in three different
patterns: (a) breathing was co-ordinated all the
time with the same phase of step, (b)
co-ordination switched suddenly from one phase
of step to another and (c) co-ordination ensued
alternatively once on the right and once on the
left leg movement. During cycling the pattern
described in (a) occurred almost
exclusively.
7. During running with a high degree of
co-ordination, oxygen uptake for a given work
load was slightly but significantly lower than
during running with weak coordination.
