ANALYSIS OF COORDINATION BETWEEN BREATHING AND EXERCISE RHYTHMS IN MAN

1. The purpose of the present study was to analyse the incidence and t ype of coordination between breathing rhythm and leg movements during running and to assess the effect of co-ordination on the running effic iency, as well as to compare the results with those found during cycli ng. 2. The experiments were carried out on thirty-four untrained volun teers exercising at two work loads (60 and 80 % of subject's physical work capacity 170) on a treadmill. In addition nineteen of the subject s exercised at the same two work loads on a bicycle ergometer. The sub jects were running at both work loads in three different modes in rand omized order: with normal arm movements, without arm movements and wit h breathing paced by an acoustic signal which was triggered by the leg movement. 3. Respiratory variables, oxygen uptake and leg movements w ere continuously recorded and evaluated on-line. The degree of co-ordi nation was expressed as a percentage of inspirations and/or expiration s starting in the same phase of the step or pedalling cycle. 4. The av erage degree of co-ordination was higher during running (up to 40%) th an 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 slightl y but not significantly with increasing work load and could be increas ed significantly by paced breathing. 6. The co-ordination between brea thing and running rhythms occurred in three different patterns: (a) br eathing 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) occ urred almost exclusively. 7. During running with a high degree of co-o rdination, oxygen uptake for a given work load was slightly but signif icantly lower than during running with weak co-ordination.