The Effects of Volitional Preemptive Abdominal Contraction on Postural Control Responses in Healthy Subjects

Abdominal bracing changes lower quarter muscle activity but not reach distances during active forward reach on an unstable surface

OBJECTIVE

This study examined the effects of abdominal bracing maneuver (ABM) performance on stable and unstable surfaces on active forward reach (AFR) distance as a measure of trunk control, measuring changes in reach distance and muscle activation patterns.

DESIGN

Single-group, repeated measures design.

METHODS

Twenty-eight subjects (mean age 25 ± 5.09 years) performed an AFR with and without ABM while on stable and unstable surfaces. Lower quarter muscle activity and forward reach distances were recorded.

RESULTS

Forward reach distances on the unstable surface were significantly decreased compared to the stable condition with and without ABM (p < .001). The surface-by-contraction interaction was significant for the tibialis anterior (TA) and gastrocnemius (GS). Significant main effects were found for internal oblique, external oblique, gluteus maximus, biceps femoris, TA, and GS, where muscle activity significantly increased during the ABM trials. The interaction between surface and contraction was significant for the TA and GS muscles. TA (p = .007) and GS (p < .001) activity increased with ABM on the unstable surface. TA activity increased with ABM on the stable surface (TA: p < .001).

CONCLUSION

Reach distances decreased on the unstable surface, but ABM did not change reaching distance. Ankle muscle co-contraction occurred during ABM trials and posterior chain activity increased. These changes suggest ABM may be beneficial during forward reaching activities.

The Effects of Abdominal Hypopressive Training on Postural Control and Deep Trunk Muscle Activation: A Randomized Controlled Trial

BACKGROUND

Abdominal Hypopressive Training (AHT) provides postural improvement, and enhances deep trunk muscle activation. However, until recently, there was a lack of scientific literature supporting these statements. The major purpose of this study was to investigate the effect of AHT on posture control and deep trunk muscle function.

METHODS

125 female participants aged 18-60 were randomly allocated to the Experimental Group (EG), consisting of two sessions of 30 min per week for 8 weeks of AHT, or the Control Group (CG), who did not receive any treatment. Postural control was measured with a stabilometric platform to assess the static balance and the activation of deep trunk muscles (specifically the Transverse Abdominal muscle (TrA)), which was measured by real-time ultrasound imaging.

RESULTS

The groups were homogeneous at baseline. Statistical differences were identified between both groups after intervention in the Surface of the Center of Pressure (CoP) Open-Eyes (S-OE) (p = 0.001, Cohen's d = 0.60) and the Velocity of CoP under both conditions; Open-Eyes (V-OE) (p = 0.001, Cohen´s d = 0.63) and Close-Eyes (V-CE) (p = 0.016, Cohen´s d = 0.016), with the EG achieving substantial improvements. Likewise, there were statistically significant differences between measurements over time for the EG on S-OE (p < 0.001, Cohen´s d = 0.99); V-OE (p = 0.038, Cohen´s d = 0.27); V-CE (p = 0.006, Cohen´s d = 0.39), anteroposterior movements of CoP with Open-Eyes (RMSY-OE) (p = 0.038, Cohen´s d = 0.60) and activity of TrA under contraction conditions (p < 0.001, Cohen´s d = 0.53).

CONCLUSIONS

The application of eight weeks of AHT leads to positive outcomes in posture control, as well as an improvement in the deep trunk muscle contraction in the female population.

The Effect of Current Low Back Pain on Volitional Preemptive Abdominal Activation During a Loaded Forward Reach Activity

BACKGROUND

A volitional preemptive abdominal contraction (VPAC) supports trunk stability during functional activity. Pain-free individuals can sustain VPAC during function, but such has not been reported for individuals with current low back pain (cLBP).

OBJECTIVE

To examine whether cLBP affects VPAC performance during a loaded forward reach (LFR) task.

DESIGN

Observational crossover study.

SETTING

Laboratory.

PARTICIPANTS

A total of 18 controls and 17 subjects with cLBP with pain ratings of 1/10 to 4/10 on a visual analog scale.

INTERVENTIONS

Transverse abdominis (TrA) thickness measurements were recorded by blinded researchers from M-mode ultrasound imaging during 4 conditions: (1) quiet standing without abdominal drawing-in maneuver (ADIM); (2) quiet standing with ADIM; (3) LFR without ADIM; and (4) LFR with ADIM. A physical therapist with 29 years of experience collected historical and examination data.

MAIN OUTCOME MEASURES

TrA muscle thickness (mm).

RESULTS

A 2 (group) × 2 (contraction) × 2 (reach) analysis of variance demonstrated a significant group × contraction interaction (F [1, 31] = 4.499, P = .04) where ADIM produced greater TrA thickness increases in PLBP subjects (2.18 mm) versus controls (1.36 mm). We observed a significant main effect for reach (F [1, 31] = 14.989, P < .001), where LFR activity produced a greater TrA thickness (6.15 ± 2.48 mm) versus quiet standing (5.30 ± 2.12 mm).

CONCLUSIONS

Subjects with cLBP demonstrated a greater increase in TrA activation during ADIM versus controls.