To establish whether McKenzie lumbar flexion and extension mobility exercises performed in lying affect central as...

Examine systemic and central hemodynamic responses following McKenzie lumbar flexion and extension mobility exercises performed in lying (FIL and EIL).

Crossover experimental study.

Clinical laboratory.

Healthy male volunteers (n=25) (mean(SD) age: 28(3)years; range 21 to 34).

Based on alternating assignment of either FIL or EIL to participants, three sets of the first exercise (10, 15, 20 repetitions) were performed with 5-minute rest between sets; after 15-minute rest, the protocol was repeated for the other exercise.

Systemic hemodynamic parameters included heart rate (HR), and systolic and diastolic blood pressures (SBP, DBP). Central hemodynamic parameters included abdominal aortic diameter (AD), peak systolic velocity (PSV/AD), end diastolic velocity (EDV/AD) and resistive index (RI). Measures recorded after each exercise set.

FIL RPP at baseline was 9.1 (1.4), after 20 repetitions 18.3 (2.5), mean difference 8.9 (95% confidence interval (CI) 7.9 to 9.8) compared to EIL at baseline 9.1 (1.5), after 20 repetitions 13.0 (3.1), mean difference 4.1 (95% CI 3.3 to 5.0). FIL RI at baseline was 0.78 (0.03), after 20 repetitions 0.87 (0.03), mean difference 0.08 (95% CI 0.06 to 0.10) compared to EIL at baseline 0.78 (0.03), after 20 repetitions 0.83 (0.03), mean difference 0.05 (95% CI 0.04 to 0.07).

Although 10 repetitions of FIL and EIL may be regarded as safe, our findings support screening patients with lifestyle risk factors, and cautioning about adhering to recommended repetition number given associated increased work of the heart. The extent of AD mechanical perturbation remains unclear.