Impact of lumbar kyphosis on gastric myoelectrical activity and heart rate variability in a model using flexion posture in healthy young adults.

Relationship between lumbar kyphotic deformity and gastroesophageal reflux disease has been indicated in recent years. But it remains unclear whether kyphotic deformity of the lumbar vertebrae affects gastric motility. Healthy young adults (n = 20) were analyzed by recording the electrogastrography (EGG) and heart rate variability (HRV) before and after meal with flexion and neutral postures. Dominant power (DP) and dominant frequency (DF) of EGG and low frequency (LF) and high frequency (HF) of HRV were analyzed in blocks of 10 minutes' duration. In neutral posture, DPs of all postprandial durations were significantly higher than those during fasting in two channels (P < 0.05, P < 0.01). However, in flexion posture, only DP at postprandial 20 (10-20 minutes after eating) in a channel was significantly higher than that during fasting (P < 0.05). DF in neutral posture was significantly higher than that in flexion posture at postprandial 20 in a channel (P < 0.05). The standard deviation of DF at postprandial 10 in flexion posture was significantly higher than that during fasting in a channel (P < 0.05). LF/HF in neural posture was significantly higher than that in flexion posture at postprandial 10 (P < 0.05). These findings suggest that inhibition of stomach myoelectrical activity was induced in the flexion posture in this lumbar kyphotic model, and autonomic activity as assessed by HRV did not accord with that expected from EGG.