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A New Study for COPDers: Mechanism of Greater Oxygen Desaturation during Walking Compared with Cycling in COPD.

Do COPDers desaturate more walking than they do cycling?  I’ve said ever since I discovered the recumbent trike existed that the recumbent trike was God’s gift to the COPDer…indeed, anyone with physical limitations.

Pedaling around the bay from the ferry on Whidbey Island with the American Lung Association of Washington’s Trek Tri Island three day cycling trip one early morning a few years ago was the first time I felt ‘normal’ again in about 7 years and the same length of time I’d gone anywhere overnight since a stay in Harrison Medical Center in 1997.

In those days I didn’t have a hip problem so I could walk without a problem other than shortness of breath but the recumbent trike lets us take our comfortable seat everywhere we pedal and stop whenever we need to take a break.  It also builds the legs muscles better and faster (my opinion) than walking and it is sure more fun and faster.

My point is wondering what the following study means in practical terms – to us, the patient.  I am one of those who do not desaturate enough for oxygen while awake.

Is cycling less strain or easier on our lungs than walking?

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“Chest. 2011 Jan 27. [Epub ahead of print]

Mechanism of Greater Oxygen Desaturation during Walking Compared with Cycling in COPD.

Mahler DA, Gifford AH, Waterman LA, Ward J, Machala S, Baird JC.

1 Section of Pulmonary & Critical Care Medicine Dartmouth Medical School, Lebanon, NH, USA.

BACKGROUND: Patients with chronic obstructive pulmonary disease (COPD) exhibit greater oxyhemoglobin desaturation during walking than with cycling. The purpose of this investigation was to investigate differences in ventilatory responses and gas exchange as proposed mechanisms for this observation.

METHODS: Arterial blood gases and lactate were measured in 12 patients with COPD (age, 68 ± 6 years) during incremental treadmill and cycle exercise. The primary outcome to assess the ventilatory response to exercise was the partial pressure of alveolar oxygen (P(A)O(2)). The primary outcome to assess impairment in exercise gas exchange was the difference between partial pressures of alveolar and arterial oxygen (P(a)O(2)) (AaPO(2)).

RESULTS: P(a)O(2) was significantly lower at peak exercise for treadmill walking (51.4 ± 6.8 mmHg) compared with cycling (60.4 ± 10.7 mmHg) (p = 0.002). The initial increase in P(A)O(2) with cycling occurred prior to the onset of the anaerobic threshold. At peak exercise, P(A)O(2) was significantly higher with cycling compared with walking (p = 0.004). The anaerobic threshold occurred at a lower VO(2) during cycling than walking (p = 0.001), and peak lactate levels were higher with cycling (p = 0.019). With progressive exercise, AaPO(2) increased similarly during treadmill and cycle exercise.

CONCLUSIONS: The higher P(A)O(2) during cycling minimized the magnitude of oxyhemoglobin desaturation compared with walking. The enhanced respiratory stimulation during cycling appears due to an initial neurogenic process, possibly originating in receptors of exercising muscles, and a subsequent earlier onset of anaerobic metabolism with higher lactate levels during cycling.”

PMID: 21273296 [PubMed – as supplied by publisher]

http://www.ncbi.nlm.nih.gov/pubmed/21273296?dopt=AbstractPlus

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I do not have a financial interest in any bike company including the recumbent trike.

More later…. Sharon O’Hara

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