Mechanism of greater XXXX desaturation during walking compared with cycling in @entity1 with @entity1030 .

@entity1 @entity26 @entity26556 @entity880 @entity1030
BACKGROUND: @entity1 with @entity1030 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 gas and @entity880 levels were measured in 12 @entity1 with @entity1030 (aged 68    6 years) during incremental treadmill and cycle exercise. The primary outcome to assess the ventilatory response to exercise was @entity26556   . The primary outcome to assess impairment in exercise gas exchange was the difference between partial pressures of alveolar and arterial @entity26 ( @entity26556    - @entity26556   ). RESULTS: @entity26556    in @entity1 was significantly lower at peak exercise for treadmill walking (51.4    6.8 mm Hg) compared with cycling (60.4    10.7 mm Hg) (P = .002). The initial increase in @entity26556    with cycling occurred prior to the onset of the anaerobic threshold. At peak exercise, @entity26556    was significantly higher with cycling compared with walking (P = .004). The anaerobic threshold occurred at a lower @entity26 consumption during cycling than walking (P = .001), and peak @entity880 levels were higher with cycling (P = .019). With progressive exercise, @entity26556    - @entity26556    increased similarly during treadmill and cycle exercise. CONCLUSIONS: The higher @entity26556    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 @entity880 levels during cycling.
