Cocontraction of ankle dorsiflexors and transversus abdominis function in patients with low back pain.

CONTEXT

The abdominal draw-in maneuver (ADIM) with cocontraction has been shown to be a more effective method of activating the transversus abdominis (TrA) in healthy adults than the ADIM alone. Whether such an augmented core stabilization exercise is effective in managing low back pain (LBP) remains uncertain.

OBJECTIVE

To determine the effect of 2 weeks of ADIM and cocontraction training on abdominal muscle thickness and activation timing and to monitor pain and function in patients with LBP.

DESIGN

Case-control study.

SETTING

Local orthopaedic clinic and research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twenty patients with mechanical LBP (age = 27.20 ± 6.46 years, height = 166.25 ± 8.70 cm, mass = 58.10 ± 11.81 kg) and 20 healthy, age-matched people (age = 24.25 ± 1.59 years, height = 168.00 ± 8.89 cm, mass = 60.65 ± 11.99 kg) volunteered for the study.

INTERVENTION(S): Both the LBP and control groups received ten 30-minute sessions of ADIM and cocontraction training of the tibialis anterior (TA) and rectus femoris (RF) muscles over a 2-week period.

MAIN OUTCOME MEASURE(S): A separate, mixed-model analysis of variance was computed for the thicknesses of the TrA, internal oblique (IO), and external oblique muscles. The differences in mean and peak electromyographic (EMG) amplitudes, onset time, and latency were compared between the groups. The visual analog pain scale, Pain Disability Index, and LBP rating scale were used to assess pain in the LBP group before and after the intervention.

RESULTS

We found an interaction between the LBP and control groups and a main effect from pretest to posttest for only TrA muscle thickness change (F₁,₃₈ = 6.57, P = .01). Reductions in all pain measures were observed after training (P < .05). Group differences in peak and mean EMG amplitudes and onset time values for TrA/IO and TA were achieved (P < .05). The RF peak (t₃₈ = 3.12, P = .003) and mean (t₃₈ = 4.12, P = .001) EMG amplitudes were different, but no group difference was observed in RF onset time (t₃₈ = 1.63, P = .11) or the cocontracted TrA/IO peak (t₃₈ = 1.90, P = .07) and mean (t₃₈ = 1.81, P = .08). The test-retest reliability for the muscle thickness measure revealed excellent correlations (intraclass correlation coefficient range, 0.95-0.99).

CONCLUSIONS

We are the first to demonstrate that a cocontraction of the ankle dorsiflexors with ADIM training might result in a thickness change in the TrA muscle and associated pain management in patients with chronic LBP.