%0 Journal Article %A Barbara Uva %A Dario Bovio %A Andrea Aliverti %T Late-breaking abstract: The diaphragm and abdominal muscles act on the abdomen to displace blood to the extremities during exercise %D 2011 %J European Respiratory Journal %P 1708 %V 38 %N Suppl 55 %X We have recently demonstrated (Aliverti et al, J Appl Physiol, 2010) that during quiet breathing the diaphragm serves the double function to ventilate the lung and to shift blood from the splanchnic vascular bed to the extremities.We hypothesized that with simultaneous contraction of abdominal muscles, such as occurs during exercise, the circulatory function of the diaphragm can be considerably enhanced.Six healthy subject performed a submaximal constant exercise workload test (repeated foot flexion at ∼60% of max workload) within a whole body plethysmography (WBP) measuring changes in body volume (dVb). Simultaneously, changes in volume of the trunk (dVtr) were measured by optoelectronic plethysmography. Blood shifts between trunk and extremities (Vbs), were determined as dVtr-dVb.In all subjects, intra-breath variations of Vbs were bimodal. Vbs initially decreased and then increased during inspiration; Vbs then decreased in the first part of expiration, and increased again in the second part. After 1 min of exercise, within-breath tidal Vbs increased by 175±122 ml (p<0.018) from rest, the blood accumulated into the extremities was 304±338 ml (p<0.05) and abdominal volume at end-expiration decreased by 0.50±0.32 L (p<0.012).We conclude that a precise control mechanism of the diaphragm and abdominal muscles determines intra-breath variations of Vbs during exercise. Due to the high frequency of tidal Vbs there is not adequate time for a complete refilling of the splanchnic blood reservoir at each abdominal compression, and this results into a significant shift of blood from the trunk to the extremities during exercise. When needed, this should be clinically useful. %U