Echocardiographic Indices of the Left and Right Heart in a Normal Black African Population.

BACKGROUND: It is unknown whether ethnic differences occur with regard to right heart echocardiographic parameters. The aim of this study therefore was to establish normative values of left and right heart parameters in a black African population and to evaluate the effect of age and body mass index (BMI) on specific right ventricle (RV) parameters. METHODS: Two hundred fifty-three normal subjects were prospectively studied. A standardized echocardiographic examination was conducted with the RV focused view used to derive RV measurements. All left and right heart measurements were made in accordance with the American Society of Echocardiography 2015 chamber guideline recommendations. Right ventricle free wall strain was assessed using an RV focused apical four-chamber view. RESULTS: The average age was 36.3 ± 12.2 years, and 59% of patients were female. The mean left ventricular ejection fraction was 62.3% ± 5.7%. The RV linear measurements (RV base, 31.0 ± 4.5 mm; midcavity, 26.3 ± 5.8 mm) were not associated with sex, age, or BMI except for the RV length (64.6 ± 8.9 mm), which was greater in male patients. Tricuspid annular plane systolic excursion (TAPSE) was 21.7 ± 2.8 mm, fractional area change was 42.1% ± 5.5%, tricuspid annular peak systolic velocity RV S' was 12.1 ± 1.9 m/sec, and RV free wall strain was -31.5% ± 8.6%. Age and BMI were not associated with right atrial (RA) volumetric measurements, RV linear measurements, or any RV functional parameters except TAPSE and RV A', which increased with BMI. CONCLUSIONS: This study establishes normal left and right heart parameters in a black African population. Aging was not associated with RA or RV parameters except for RV E' and A'. BMI does not affect RA/RV measurements but may cause variability in TAPSE and RV A'.

Biomechanical analysis of running in military boots with new and degraded insoles.

PURPOSE: The purpose of the present study was to investigate the influence of degradation using repeated impacts on the ability of different shock-absorbing insoles to reduce peak impact loading during running in military boots. METHODS: Four insole types were degraded mechanically to simulate typical running loads that occur during approximately 100 km of running. The influence of insole mechanical degradation on stiffness and impact-absorbing ability was assessed using standard test procedures. The ability of new and degraded insole samples to reduce peak impact loading during running was assessed by monitoring peak impact force and rate of loading. In addition, the influence of insoles on sagittal plane kinematics was quantified by measurement of hip, knee, and ankle joint flexion. RESULTS: Insole mechanical degradation resulted in an increase in mechanical stiffness and a decrease in ability to reduce mechanical impacts for all test insoles. Measurements taken during running indicated that only one insole type reduced peak impact loading when new, as indicated by a significant (P< 0.05) reduction in peak rate of loading. The ability of this insole type to reduce peak rate of loading during running was maintained after mechanical degradation. This insole was also found to significantly (P< 0.05) reduce peak ankle dorsiflexion. CONCLUSION: The present study identifies an insole type that reduces peak rate of loading during running both when new and when mechanically degraded. It is suggested that this indicates an insole that could potentially reduce the frequency of overuse injuries. Based on these results, this insole is recommended for use in the investigation of the practical use of insoles by military recruits, particularly for study of the influence on injury occurrence.

The influence of simulated wear upon the ability of insoles to reduce peak pressures during running when wearing military boots.

Mechanical degradation of three types of shock absorbing insoles equivalent to 100-130 km of running did not reduce their ability to attenuate the peak pressures generated during running when wearing military boots. Pressure measurements at the heel and forefoot were recorded with pressure measuring insoles placed in the boots of nine subjects. Two of the three insoles tested reduced the peak pressures (P<0.05) generated at the heel and forefoot relative to the no-insole (control) condition. The most effective insole reduced the peak pressures at the heel by 37% and at the forefoot by 24%.