Intra-abdominal pressure and rowing: the effects of inspiring versus expiring during the drive

Background, The lumbar vertebrae of rowers are subjected to high levels of shear and compression at mid-drive, but intraabdominal pressure (IAP) may p artially neutralize these forces. IAP fluctuates with breathing. This study compared the IAP between inspiring during the drive and expiring during th e drive. Methods, Experimental design: ten volunteers performed one 5x2-minute repet ition test while ispiring during the drive and one 5x2-minute repetition te st while expiring during the drive on a rowing ergometer. The five work rat es were: 100, 125, 150, 175 and 200 watts at 22, 24, 26, 28 and 30 strokes per minute, respectively, Measures: the movement of the body while rowing w as analyzed using a position sensor, and IAP was measured using a pressure transducer catheter. Results, A 2x5 repeated measures analysis of variance showed that there was a significant interaction for the dependent variable mid-drive IAP (p<0.05 ), with the mid-drive IAP increasing at a greater rate while expiring durin g the drive relative to inspiring during the drive Across work rate, the mi d-drive IAP and minimal IAP were significantly higher while expiring during the drive than inspiring during the drive (p<0.05). Across breathing patte rn, the minimal IAP maximal IAP, average change in IAP and mid-drive IAP in creased significantly with work rate (p<0.05). Conclusions. The data show that expiring during the drive leads to a greate r mid-drive IAP than inspiring during the drive.