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.

Digital fluoroscopic video assessment of glenohumeral migration: Static vs. Dynamic conditions.

The purpose was to compare glenohumeral (GH) migration, during dynamic shoulder elevation and statically held positions using digital fluoroscopic videos (DFV). Thirty male volunteers (25+/-4 years) without right shoulder pathology were analyzed using DFV (30Hz) during arm elevation in the scapular plane. DFV were obtained at the arm at side position, 45 degrees , 90 degrees , and 135 degrees for static and dynamic conditions. GH migration was measured as the distance from the center of the humeral head migrated superiorly or inferiorly relative to the center of the glenoid fossa. Inter-rater reliability was considered good; ICC (2,3) ranged from 0.83 to 0.92. A main effect was revealed for contraction type (p=0.031), in which post-hoc t-tests revealed that humeral head was significantly more superior on the glenoid fossa during dynamic contraction. A main effect was also revealed for arm angle (p<0.001), in which post-hoc t-tests revealed significantly more superior humeral head positioning at 45 degrees , 90 degrees , and 135 degrees when compared to arm at side (p<0.001), as well as at 90 degrees compared to 45 degrees (p=0.024). There was no interaction effect between angle and contraction type (p=0.400). Research utilizing static imaging may underestimate the amount of superior GH migration that occurs dynamically.

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.

Fluoroscopic assessment of rotator cuff fatigue on glenohumeral arthrokinematics in shoulder impingement syndrome.

BACKGROUND: Although prior researchers have assessed glenohumeral arthrokinematics using isometrically held arm postures with standard radiographs, dynamic assessment of glenohumeral arthrokinematics has been limited. This study utilized video fluoroscopy to analyze superior inferior glenohumeral migration during dynamic arm elevation in individuals with outlet impingement syndrome, before and after fatigue of the rotator cuff. HYPOTHESIS: Prior to the study, it was hypothesized that during the pre-fatigue state, glenohumeral migration would be in the superior direction, and that post-fatigue there would be a significant increase in superior migration. MATERIALS AND METHODS: Digital fluoroscopic videos (30 Hz) were used to analyze 20 male volunteers (27.7 +/- 7.3 years) with right shoulder outlet impingement syndrome during concentric elevation of the arm in the plane of the scapula, both before and after fatigue of the rotator cuff. RESULTS: During concentric arm elevation, there was superior glenohumeral migration (1.6 mm) between 45 degrees and 90 degrees of arm elevation, regardless of fatigue-state (P = .02). After rotator cuff fatigue, the humeral head was positioned more superiorly on the glenoid fossa (P = .03). The position of the humeral head was 0.4 mm more superior than that reported in a previous study on healthy individuals. CONCLUSION: These results support prior findings that suggest superior glenohumeral migration during arm elevation is influenced both by shoulder pathology and the state of fatigue of the rotator cuff musculature. Future research should examine the effects of physical therapy and surgical interventions on glenohumeral arthrokinematics to better determine the most effective treatment methods for outlet impingement. LEVEL OF EVIDENCE: Controlled laboratory study.

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.

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.

The effect and safety of short-term creatine supplementation on performance of push-ups.

The effects of short-term oral creatine (Cr) supplementation on exercise performance and on blood pressure and renal function were assessed. Thirty-five healthy, active duty, U.S. Army volunteers (20 men and 15 women; age, 22-36 years) at Fort Sam Houston, Texas, supplemented their diet for 7 days with 20 g/day of either Cr or taurine (as placebo). There was no significant difference in 2-minute push-up counts between the Cr and taurine groups from before to after supplementation (p = 0.437; power = 0.98). The Cr group demonstrated a significant increase in serum creatinine levels (p < 0.001), compared with the taurine group, and this increase could be misinterpreted as impairment of renal function. No adverse changes in blood pressure, body composition, weight, or serum Cr phosphokinase levels were observed. We conclude that short-term Cr supplementation appears to be safe but does not enhance push-up performance.