Dishman JD, et al. - Researchers performed a comparison of a time series of tibial nerve H-reflex trials between patients with subacute low back pain (LBP) and asymptomatic adults using pre and post high-velocity, low-amplitude (HVLA) spinal manipulation (SM) and control procedures. They randomized asymptomatic adults (n = 66) and patients with subacute LBP (n = 45) into 3 lumbosacral procedures (side-posture positioning, joint preloading with no thrust, and HVLA SM) and recorded a time series of 40 H_max/M_max ratios at a rate of 0.1 Hz in blocks of 10 trials at baseline and after the lumbosacral procedures at time points corresponding to immediately after, 5 minutes after, and 10 minutes after the procedure. Despite the presence of nonspecific effects of movement or position artifacts on the H_max/M_max ratio, they noted a reliable and valid attenuation of the H_max/M_max ratio as a specific aspect of HVLA SM in both asymptomatic adults and patients with subacute LBP.