THE EFFICACY OF AN EIGHT-WEEK CORE STABILIZATION PROGRAM ON CORE MUSCLE FUNCTION AND ENDURANCE: A RANDOMIZED TRIAL.

BACKGROUND: Body armor is credited with increased survival rates in soldiers but the additional axial load may negatively impact the biomechanics of the spine resulting in low back pain. Multiple studies have found that lumbar stabilization programs are superior to generalized programs for patients with chronic low back pain. It is not known if such programs produce objective changes in trunk muscle function with wear of body armor. HYPOTHESIS/PURPOSE: An eight-week core stability exercise program would result in a larger improvement in physical endurance and abdominal muscle thickness than a control intervention. The purpose of this study was to assess the effectiveness of an eight-week core stability exercise program on physical endurance and abdominal muscle thickness with and without wear of body armor. STUDY DESIGN: Randomized controlled trial. METHODS: Participants (N = 33) were randomized into either the core strengthening exercise group or the control group. Testing included ultrasound imaging of abdominal muscle thickness in hook-lying and standing with and without body armor and timed measures of endurance. RESULTS: There were statistically significant group by time interactions for transversus abdominis muscle contraction thickness during standing, both with (p = 0.018) and without body armor (p = 0.038). The main effect for hold-time during the horizontal side-support (p = 0.016) indicated improvement over time regardless of group. There was a significant group by time interaction (p = 0.014) for horizontal side-support hold-time when compliance with the exercise protocol was set at 85%, indicating more improvement in the core stabilization group than in the control group. CONCLUSION: Performing an eight-week core stabilization exercise program significantly improves transversus abdominis muscle activation in standing and standing with body armor. When compliant with the exercises, such a program may increase trunk strength and muscle endurance. LEVELS OF EVIDENCE: Therapy, Level 2b.

ULTRASOUND IMAGING MEASUREMENT OF THE TRANSVERSUS ABDOMINIS IN SUPINE, STANDING, AND UNDER LOADING: A RELIABILITY STUDY OF NOVICE EXAMINERS.

BACKGROUND: Military personnel and first responders (police and firefighters) often carry large amounts of gear. This increased load can negatively affect posture and lead to back pain. The ability to quantitatively measure muscle thickness under loading would be valuable to clinicians to assess the effectiveness of core stabilization treatment programs and could aid in return to work decisions. Ultrasound imaging (USI) has the potential to provide such a measure, but to be useful it must be reliable. PURPOSE: To assess the intrarater and interrater reliability of measurements of transversus abdominis (TrA) and internal oblique (IO) muscle thickness conducted by novice examiners using USI in supine, standing, and with an axial load. STUDY DESIGN: Prospective, test-retest study. METHODS: Healthy, active duty military (N=33) personnel were examined by two physical therapy doctoral students (primary and secondary ultrasound technicians) without prior experience in USI. Thickness measurements of the TrA and IO muscles were performed at rest and during a contraction to preferentially activate the TrA in three positions (hook-lying, standing, and standing with body armor). Percent thickness changes and intraclass correlation coefficients (ICC) were calculated. RESULTS: Using the mean of three measurements for each of the three positions in resting and contracted muscle states, the intrarater ICC (3,3) values ranged from 0.90 to 0.98. The interrater ICC (2,1) values ranged from 0.39 to 0.79. The ICC values of percent thickness changes were lower than the individual ICC values for all positions and muscle states. CONCLUSION: There is excellent intrarater reliability of novice ultrasound technicians measuring abdominal muscle thickness using USI in three positions during the resting and contracted muscle states. However, interrater reliability of two novice technicians was poor to fair, so additional training and experience may be necessary to improve reliability. LEVEL OF EVIDENCE: 2b.

Transfemoral amputations: is there an effect of residual limb length and orientation on energy expenditure?

BACKGROUND: Energy cost of ambulation has been evaluated using a variety of measures. With aberrant motions resulting from compensatory strategies, persons with transfemoral amputations generally exhibit a larger center of mass excursion and an increased energy cost. However, few studies have analyzed the effect of residual femur length and orientation or energy cost of ambulation. QUESTIONS/PURPOSES: The purpose of this study was to compare residual limb length and orientation with energy efficiency in patients with transfemoral amputation. We hypothesized that patients with shorter residual limbs and/or more abnormal residual femur alignment would have higher energy expenditure cost and greater center of mass movement than those with longer residual limbs resulting from lacking musculature, shorter and/or misoriented lever arms, and greater effort required to ambulate through use of compensatory movements. METHODS: Twenty-six adults with acute, trauma-related unilateral transfemoral amputations underwent gait and metabolic analysis testing. Patients were separated into groups for analysis based on residual limb length and residual femoral angle. RESULTS: Cohorts with longer residual limbs walked faster than those with shorter residual limbs (self-selected walking velocity 1.28 m/s versus 1.11 m/s, measured effect size = 1.08; 95% confidence interval = short 1.10-1.12, long 1.26-1.30; p = 0.04). However, there were no differences found with the numbers available between the compared cohorts regardless of limb length or orientation in regard to O2 cost or other metabolic variables, including the center of mass motion. CONCLUSIONS: Those with longer residual limbs after transfemoral amputation chose a faster self-selected walking velocity, mirroring previous studies; however, metabolic energy and center of mass metrics did not demonstrate a difference in determining whether energy expenditure is affected by length or orientation of the residual limb after transfemoral amputation. These factors may therefore have less effect on transfemoral amputee gait efficiency and energy requirements than previously thought.

Kinematic analysis of males with transtibial amputation carrying military loads.

The biomechanical responses to load carriage, a common task for dismounted troops, have been well studied in nondisabled individuals. However, with recent shifts in the rehabilitation and retention process of injured servicemembers, there remains a substantial need for understanding these responses in persons with lower-limb amputations. Temporal-spatial and kinematic gait parameters were analyzed among 10 male servicemembers with unilateral transtibial amputation (TTA) and 10 uninjured male controls. Participants completed six treadmill walking trials in all combinations of two speeds (1.34 and 1.52 m/s) and three loads (none, 21.8, and 32.7 kg). Persons with TTA exhibited biomechanical compensations to carried loads that are comparable to those observed in uninjured individuals. However, several distinct gait changes appear to be unique to those with TTA, notably, increased dorsiflexion (deformation) of the prosthetic foot/ankle, less stance knee flexion on the prosthetic limb, and altered trunk forward lean/excursion. Such evidence supports the need for future work to assess the risk for overuse injuries with carried loads in this population in addition to guiding the development of adaptive prosthetic feet/components to meet the needs of redeployed servicemembers or veterans/civilians in physically demanding occupations.

Transfemoral amputations: the effect of residual limb length and orientation on gait analysis outcome measures.

BACKGROUND: The level of function achieved following a transfemoral amputation is believed to be affected by surgical attachment of the remaining musculature, resulting orientation of the femur, residual limb length, and eventual prosthetic fit. METHODS: Twenty-six subjects underwent gait analysis testing in the current preferred prosthesis more than twenty-four months postamputation. The femoral length and orientation angles of each subject were measured from standing postoperative radiographic scanograms. The subjects were separated into groups for analysis on the basis of the femoral shaft angles and the residual limb length ratios. Gait analysis was performed to collect kinematic and temporospatial parameters. RESULTS: A good correlation was observed between residual femoral length and trunk with regard to forward lean (r = -0.683) and lateral flexion (r = -0.628). A good correlation was also observed between residual femoral length and pelvic motion with regard to pelvic tilt (r = -0.691) and obliquity (r = -0.398). A moderate correlation was observed with speed (r = 0.550), indicating that subjects with shorter residual limbs experienced a greater excursion in the torso and pelvis, while walking at a slower self-selected pace. A significant correlation (r = 0.721, p < 0.001) was observed between the femoral shaft abduction angle and the residual femoral length; the shorter the residual limb, the more abducted it was. CONCLUSIONS: The length of the residual femur substantially influences temporospatial and kinematic gait outcomes following transfemoral amputation, and appears to be more important than femoral orientation with regard to these parameters.

Metabolic analysis of male servicemembers with transtibial amputations carrying military loads.

For servicemembers who have sustained amputations and wish to return to Active Duty, performing common military tasks is essential. The purpose of this study was to examine the metabolic requirements of servicemembers with transtibial amputations wearing a loaded rucksack and walking at a steady speed. We tested 12 servicemembers with unilateral transtibial amputations and 12 uninjured controls on a treadmill at two walking speeds (1.34 and 1.52 m/s) while they carried a 32.7 kg load. Oxygen consumption was recorded. Results showed that metabolic demand for the injured servicemembers was significantly higher (8.5% at 1.34 m/s and 10.4% at 1.52 m/s) than for controls. An understanding of energy expended during load carriage by this study population is critical for decisions regarding return-to-duty requirements. Although significant differences existed between uninjured controls and those with amputations, it is important to note that those differences are less than previously published. This finding, coupled with the fact that servicemembers with transtibial amputations have redeployed, implies that, despite statistical significance, results may not be clinically relevant. Future work should include more taxing conditions to identify a threshold for potential limitations.