Joseph M. Molloy

Changes in Deep Abdominal Muscle Thickness During Common Trunk-Strengthening Exercises Using Ultrasound Imaging

STUDY DESIGN Cross-sectional study design. OBJECTIVES To characterize changes in muscle thickness in the transversus abdominis (TrA) and internal oblique (IO) muscles during common trunk-strengthening exercises, and to determine whether these changes differ based on age. BACKGROUND Although trunk-strengthening exercises have been found to be useful in treating those with low back pain (LBP), our understanding of the relative responses of the TrA and IO muscles during different exercises is limited. METHODS AND MEASURES Six commonly prescribed trunk-strengthening exercises were performed by 120 subjects (40 subjects per age group: 18-30, 31-40, and 41-50 years). Ultrasound imaging was used to measure the thickness of the TrA and IO during the resting and contracted state of each exercise. The average thickness of the muscles while in the contracted position was divided by the thickness values in the resting position for each exercise, based on 2 performances of each exercise. Two 3-by-6 repeated-measures analyses of variance were used to determine significant changes in muscle thickness of the TrA and IO, based on age group and exercise performed. RESULTS For both muscles, the trunk exercise-by-age interaction effect (TrA, P = .358; IO, P = .217) and the main effect for age (TrA, P = .615; IO, P = .219) were not significant. A significant main effect for trunk exercise for both muscles (P<.001) was found. The horizontal side-support (mean +/- SD contracted-rest thickness ratio: TrA, 1.95 +/- 0.69; IO, 1.88 +/- 0.52) and the abdominal crunch (mean +/- SD contracted-rest thickness ratio: TrA, 1.74 +/- 0.48; IO, 1.63 +/- 0.41) exercises resulted in the greatest change in muscle thickness for both muscles. The abdominal drawing-in maneuver (mean +/- SD contracted-rest thickness ratio: TrA, 1.73 +/- 0.36; IO, 1.14 +/- 0.33) and quadruped opposite upper and lower extremity lift (mean +/- SD contracted-rest thickness ratio: TrA, 1.59 +/- 0.49; IO, 1.25 +/- 0.36) exercises resulted in changes in TrA muscle thickness with minimal changes in IO muscle thickness. CONCLUSION Changes in TrA and IO muscle thickness differed across 6 commonly prescribed trunk-strengthening exercises among healthy subjects without LBP. These differences did not vary by age. This information may be useful for informing exercise prescription.

Changes in Lateral Abdominal Muscle Thickness During the Abdominal Drawing-in Maneuver in Those With Lumbopelvic Pain

STUDY DESIGN Controlled laboratory study. OBJECTIVES To determine if changes in transversus abdominis (TrA) and internal oblique (IO) muscle thickness and side-to-side symmetry differ in individuals with and without unilateral lumbopelvic pain while at rest and during the abdominal drawing-in maneuver (ADIM). BACKGROUND Although the ADIM has been found to produce a symmetrical change in TrA and IO muscle thickness in healthy subjects, how these muscles are activated in those with unilateral lumbopelvic pain during the ADIM remains unknown. METHODS Fifteen subjects with lumbopelvic pain and 15 age- and gender-matched control subjects were recruited. To investigate a similar subgroup of patients with lumbopelvic pain that has been used in previous research, subjects were required to have unilateral symptoms, a positive sacroiliac provocation test, and a positive active straight-leg raise test. Ultrasound images were obtained bilaterally at 2 different points during each trial of the ADIM: (1) at rest and (2) while maintaining the ADIM. Average percent change in thickness of the TrA and IO muscles was obtained over 3 trials. RESULTS The percent change in thickness of the TrA was 20.9% less in those with lumbopelvic pain compared to the control group (P = .035), while the percent change in IO thickness was equivalent between groups (P = .522). No differences were observed for the TrA or IO muscles between the symptomatic and asymptomatic sides in those with (TrA, P = .263; IO, P = .172) or without (TrA, P = .780; IO, P = .635) lumbopelvic pain during the ADIM. Changes in TrA muscle thickness were greater than the IO muscle during the ADIM for both groups (P<.001). Specifically, the increases in TrA muscle thickness in those with and without lumbopelvic dysfunction were 32.7% and 47.3% greater, respectively, compared to changes in the IO muscle. CONCLUSIONS Individuals with unilateral lumbopelvic pain demonstrated a smaller increase in thickness of the TrA muscle during the ADIM. This finding provides an element of construct validity for the use of the ADIM for assessing TrA muscle thickness in those with unilateral lumbopelvic pain. However, both groups demonstrated a symmetrical side-to-side change in TrA and IO muscle thickness despite the symptomatic group having unilateral symptoms. Further, we detected a preferential change in TrA muscle thickness during the ADIM in both groups.

Effect of using truncated versus total foot length to calculate the arch height ratio

OBJECTIVE The purpose of this study was to determine the arch height ratio in a large cohort of subjects as well as to assess the reliability and validity of the foot measurements utilized in the study. METHOD Eight hundred and fifty subjects, 393 women and 457 men, consented to participate in the study. The dorsal arch height, total foot length, and the truncated foot length were used to calculate two variations of the arch height ratio. In addition to determining within- and between-rater measurement reliability, radiographs were used to establish validity. RESULTS The truncated arch height ratio can be estimated using the total foot length, unless toe deformities are present in the individual being assessed. All foot measurements had high levels of intra- and inter-rater reliability and the validity of measuring the dorsal arch height while standing with equal weight on both feet was established. CONCLUSIONS This investigation provides normative values from a large cohort of healthy female and male subjects for two variations of the arch height ratio. The arch height ratio is a reliable and valid measurement that may prove useful to clinicians and researchers for the classification of foot posture.

Dynamic plantar pressure parameters associated with static arch height index during gait

BACKGROUND Although extreme values of arch height have been associated with increased risk for overuse injury, knowledge is limited regarding the association between arch height and plantar pressure distributions during gait. The primary purpose of this study was to explore which plantar pressure measurements during gait were associated with static arch height and arch height index. METHODS Static arch height, arch height index, and dynamic plantar pressure distributions were collected for 1000 subjects (566 males, 434 females, 30.6 [SD 8.0] years, 171.1 [SD 9.3]cm, 76.9 [SD 14.7]kg). A hierarchical regression analysis was performed to determine the most parsimonious set of plantar pressure parameters associated with arch height. The predicted values were used to calculate dynamic arch height index. Correlation and residual analysis were performed to assess the association between statically and dynamically determined arch height indices. FINDINGS A 5-variable model (F = 296.6; P < 0.001) was able to describe the relationship between static arch height and the dynamic foot during gait (R =0 .77 [95% CI = 0.75-0.80]). The correlation between the static and dynamically determined arch height indices was r = 0.60 (95% CI = 0.53, 0.63), with a mean residual of 0.000 (SD 0.015). INTERPRETATION A multivariate model generated by plantar parameters during gait was able to predict 60% of the variability in static arch height. This model consisted of variables that appear to be clinically plausible and inform the association between static arch height and dynamic foot posture. Future researchers should address the association between statically and dynamically determined AHI values with lower extremity overuse injuries.

Static Foot Posture Associated With Dynamic Plantar Pressure Parameters

STUDY DESIGN Controlled laboratory study. OBJECTIVE To explore potential associations between foot posture index (FPI-6) composite scores and dynamic plantar pressure measurements, and to describe each of the 6 subscales and the FPI-6 composite scores across our sample. BACKGROUND The FPI-6 is a static foot posture assessment comprised of 6 observations. Extreme scores have been associated with increased injury risk. However, knowledge describing the relationship between FPI-6 scores and plantar pressure distributions during gait is limited. METHODS Participants (n = 1000; 566 males, 434 females) were predominantly active adults (mean ± SD age, 30.6 ± 8.0 years; body mass index, 26.2 ± 3.7 kg/m²), who ran 3.1 ± 1.4 d/wk. Static and dynamic foot characteristics were compared using the FPI-6 and a capacitance-based pressure platform. Correlation and hierarchical stepwise regression analyses were performed to determine the most parsimonious set of dynamic pressure data associated with FPI-6 scores. RESULTS The mean ± SD FPI-6 score was 3.4 ± 2.9 (range, -6.0 to 11.0). Only 31 participants received a score of -2 (supinated foot) on any FPI-6 subscale. Classification of a pronated foot was 2.4 times more likely than a supinated foot. A 5-variable model (R = 0.57, R2 = 0.32) was developed to describe the association between dynamic plantar pressures and FPI-6 scores. CONCLUSION The multivariate model associated with FPI-6 scores comprised clinically plausible variables which inform the association between static and dynamic foot postures. Different cutoff values may be required when using the FPI-6 to screen for individuals with supinated feet, given the limited number of high-arched participants identified by FPI-6 classifications.

Physical training injuries and interventions for military recruits.

Low physical fitness levels are associated with increased musculoskeletal injury risk and attrition among military recruits. The authors review physical fitness trends, injury risk factors, and Department of the Army initiatives to address recruit fitness, injuries, and attrition. Initiatives include the Fitness Assessment Program, which reduced injury risk and attrition among low-fit trainees, and the Assessment of Recruit Motivation and Strength, which enabled the Army to enlist individuals exceeding body composition accession standards without increasing attrition. Physical Readiness Training (PRT) is the Armys primary initiative to address training-related injuries and attrition. PRTs inherent injury control and exercise progression components are designed to address low fitness levels across entry-level training. PRT has been shown to decrease injury rates, but low-fit recruits remain at increased risk regardless of program design. The authors recommend resuming pre-enlistment fitness screening and fitness programming before low-fit recruits begin entry-level training. The decision whether to screen for fitness before beginning entry-level training could be based upon the existing recruiting environment in terms of applicant supply and the demand for recruits. However, the Army should anticipate increased injury and attrition rates when discontinuing screening and/or fitness programming for low-fit recruits.

Effect of running shoe type on the distribution and magnitude of plantar pressures in individuals with low- or high-arched feet.

BACKGROUND Research addressing the effect of running shoe type on the low- or high-arched foot during gait is limited. We sought 1) to analyze mean plantar pressure and mean contact area differences between low- and high-arched feet across three test conditions, 2) to determine which regions of the foot (rearfoot, midfoot, and forefoot) contributed to potential differences in mean plantar pressure and mean contact area, and 3) to determine the association between the static arch height index and the dynamic modified arch index. METHODS Plantar pressure distributions for 75 participants (40 low arched and 35 high arched) were analyzed across three conditions (nonshod, motion control running shoes, and cushioning running shoes) during treadmill walking. RESULTS In the motion control and cushioning shoe conditions, mean plantar contact area increased in the midfoot (28% for low arched and 68% for high arched), whereas mean plantar pressure decreased by approximately 30% relative to the nonshod condition. There was moderate to good negative correlation between the arch height index and the modified arch index. CONCLUSIONS Cushioning and motion control running shoes tend to increase midfoot mean plantar contact area while decreasing mean plantar pressure across the low- or high-arched foot.

Factors Influencing Running-Related Musculoskeletal Injury Risk Among U.S. Military Recruits.

Running-related musculoskeletal injuries among U.S. military recruits negatively impact military readiness. Low aerobic fitness, prior injury, and weekly running distance are known risk factors. Physical fitness screening and remedial physical training (or discharging the most poorly fit recruits) before entry-level military training have tended to reduce injury rates while decreasing attrition, training, and medical costs. Incorporating anaerobic running sessions into training programs can offset decreased weekly running distance and decrease injury risk. Varying lower extremity loading patterns, stride length or cadence manipulation, and hip stability/strengthening programming may further decrease injury risk. No footstrike pattern is ideal for all runners; transitioning to forefoot striking may reduce risk for hip, knee, or tibial injuries, but increase risk for calf, Achilles, foot or ankle injuries. Minimal evidence associates running surfaces with injury risk. Footwear interventions should focus on proper fit and comfort; the evidence does not support running shoe prescription per foot type to reduce injury risk among recruits. Primary injury mitigation efforts should focus on physical fitness screening, remedial physical training (or discharge for unfit recruits), and continued inclusion of anaerobic running sessions to offset decreased weekly running distance.

Awareness and Compliance With Recommended Running Shoe Guidelines Among U.S. Army Soldiers

The purpose of this study was to determine awareness and compliance with recommended running shoe selection, sizing, and replacement guidelines among U.S. Army soldiers. Soldiers (n = 524) attending training at Fort Sam Houston, Texas completed self-report questionnaires and a foot assessment, which included measurement of foot size and arch height index. Researchers examined each soldiers running shoes for type, wear pattern, and general condition. Thirty-five percent of the soldiers wore shoes that were inappropriately sized; 56.5% wore shoes that were inappropriate for their foot type. Thirty-five percent of the soldiers had excessively worn shoes and 63% did not know recommended shoe replacement guidelines. Further efforts may be necessary to ensure that soldiers are aware of and compliant with recommended running shoe selection, sizing, and replacement guidelines. Future research is needed to determine whether adherence to these guidelines has a favorable effect on reducing risk of overuse injury.

Triceps Tendon Tear in a Middle-Aged Weightlifter

The patient was a 47-year-old man who was evaluated by a physical therapist for a chief complaint of posterior right elbow pain. The patient routinely participated in weightlifting activities and reported a sudden onset of triceps weakness and posterior elbow pain while performing clap push-ups 3 days prior. A physician assistant ordered radiographs, which were initially interpreted as normal, and routine magnetic resonance imaging for the right elbow. Following examination by a physical therapist, due to concern for a triceps tendon tear, the previously ordered magnetic resonance imaging was expedited, which revealed a partial triceps tendon tear with partial tendon retraction medially.