Reproducibility of ultrasound blood flow measurement of the superior mesenteric artery before and after exercise

This study examines the reproducibility of gastro-intestinal blood flow mea surements in the superior mesenteric artery (SMA) both before and immediate ly after exercise with Doppler ultrasound measurements. Twelve well-trained males (mean +/- SD: age 25.9 +/- 3.8 yr; (V) over dot O-2 max 4.8 +/- 0.9 l x min(-1)) were measured twice (trial 1 and 2) with a 1 week interval bef ore and immediately after 1 hr cycling at 70 % (V) over dot O-2 max. Duplex scanning was performed with the athletes in supine position immediately af ter transition from a chair (before exercise) or bicycle (after exercise). The variability of three measurements before exercise was studied within bo th trials (short-term reproducibility) and the mean pre-exercise values wer e compared between the trials (long-term reproducibility), in addition, pos t-exercise measurements were compared in the same way. Reproducibility was tested using the coefficient of variation and Cronbach's alpha. Mean pre-ex ercise blood flow was 424 +/- 66 ml/min (n = 12) in trial 1 and 375 +/- 38 ml/min (n = 11) in trial 2, Immediately after exercise blood flow had decre ased by 49% to 214 +/- 36 ml/min (p < 0.01) in trial 1 and by 38% to 234 +/ - 36 ml/min (p < 0.01) in trial 2. Blood flow before and after exercise was not significantly different between trials (paired t-test) and therefore r eproducible at the group level. Before exercise a good to fair reproducibil ity was observed both at the short-term (Cronbach's alpha: 0.88 in trial 1, 0.73 in trial 2, n = 11), and at the long-term (alpha = 0.80, n = 11). In contrast, long-term reproducibility immediately after exercise was poor (al pha = -0.99, n = 8 and alpha = 0.36, n = 7 after the first and second cycli ng period, respectively). In conclusion, duplex scanning of SMA after a sit ting-supine transition in well-trained subjects is not a reproducible metho d at the individual level for intestinal blood flow measurements immediatel y after exercise.