The relationship between biomechanical-anthropometrical parameters and the force exerted on the head when heading free kicks in soccer

Background:

Soccer is a contact sport in which the players are frequently faced with the risk of injury. It has been shown that the force exerted on the head during heading can be as much as 500–1200 Newton (N).

Objectives:

The main objective of this study was to determine whether there was any relationship between the force exerted on the head and several biomechanical and anthropometrical parameters related to heading free kicks.

Patients and Methods:

A total of 16 semi-professional soccer players with at least 5 years experience participated in this study. The mean age, height, and weight of the study participants were 21.36 ± 5.67, 178 ± 5.99 cm, and 70.55 ± 8.55 kg, respectively. To measure the force exerted on the heads of the players, a pressure gauge was installed on their foreheads. Each participant was asked to defend the ball using the heading technique three times. A camera with a sampling frequency of 150 frames per second was used to record the moment of impact between the ball and head during each heading event. For each participant and replicate, the ball and head velocity (m/s) as well as the angular body changes (degrees) were calculated using MATLAB and AutoCAD softwares, respectively. Descriptive statistics, including means and standard deviations were used to describe the data. Pearson correlation coefficient (alpha = 0.05) was used to examine potential relationships between the variables of interest.

Results:

Significant correlations existed between the force exerted on the head during heading, participant age, body mass, body fat percentage, and head perimeter (P < 0.05).

Conclusions:

The study revealed the significance of anthropometric variables related to heading, such as age and head perimeter. Therefore, it was concluded that these variables should be considered when teaching and practicing the heading technique with players of different ages and anthropometric sizes.

Trichinella infection in wildlife of northeast of iran

BACKGROUND

The objective of this investigation was to detect the presence of Trichinella in some carnivores of Mashhad in northeast of Iran and to identify Trichinella species circulating in this area.

METHODS

The present study was carried out using muscle tissue collected from 120 stray dogs, 26 wild boars, 25 rodents, two foxes and two hyenas captured in Mashhad City, province of Khorasan Razavi, Iran.

RESULTS

Trichinella larvae were detected in three stray dogs by artificial digestion and compression. All larvae were identified as T. britovi using multiplex PCR.

CONCLUSION

This is the first report of identification of T. britovi in stray dog in Iran.

Anopheline species composition in borderline of Iran-Azerbaijan

Malaria is still one of the most important health-problems in the world and is endemic in Iran. Since 1994, after collapse of former Soviet Union, a new threat of malaria importation emerged from those countries into the northern Iran. This work was carried out to provide further evidence on the status of anopheline species composition, the malaria parasite species, and natural infectivity of mosquitoes distributed in Pars-Abad district, on the borderline of Azerbaijan in northwestern Iran. Mosquitoes were collected from May to December 2008 in anopheline seasonal activity and were identified at the species level. The genus- and species-specific primers against Plasmodium ssrDNA gene were used for specific amplification on female mosquito head+thorax. Members of the Anoheles maculipennis complex were identified by sequence analysis of the ribosomal internal transcribed spacer II (ITS2-rDNA). Morphological character-based identification showed that out of 1455 anopheline female specimens, 1121 (77%) were of A. maculipennis s.l. and 334 (23%) were of Anoheles hyrcanus. Molecular analysis of the species complex indicated the presence of Anoheles sacharovi 984 (67.6%) and A. maculipennis 137 (9.4%) in the region. None of themosquito's head-thorax was found to be naturally infected by malaria parasite. Results of this study, particularly high dominance of A. sacharovi, suggest a potential risk of malaria epidemic in the region, and the need for a continuous epidemiological surveillance.

Effect of trunk inclination on lower limb joint and lumbar moments in able men during the stance phase of gait

BACKGROUND

Though the effect of imposed trunk posture affects walking patterns little is known about the effect of natural orientation of the trunk on gait. The objectives of this study are to test if the lower limb joint and thoraco-lumbar moments are similar in subjects who maintain an average natural forward or backward trunk inclination during gait and verify if the lower limbs are equally affected.

METHODS

Twenty-five young men were divided according to their natural backward or forward trunk inclination during level walking. Ankle, knee, hip and thoraco-lumbar moments were calculated by an inverse dynamic approach for the two limbs. A two-way ANOVA was performed on peak lower limb moments. A one-way ANOVA was performed on thoraco-lumbar peak moments.

FINDINGS

There was a main effect for both trunk inclinations and lower limb sides but no interaction. For the forward leaners, the duration of hip extension moment was longer (P<0.001) while the hip flexion moment was 1.3 times smaller (P<0.001). Differences between the lower limb sides were noted in all joints but at push-off of the stance phase only. The two thoraco-lumbar extension moments were, respectively, 1.4 times higher for the forward leaners while the two flexion moments were approximately 1.4 times higher for the backward leaners.

INTERPRETATIONS

The backward leaners propel themselves with a strong hip flexor activity at push-off while the forward leaners use their hip muscles throughout stance. These results support the idea that trunk inclinations and moment variations are associated with the type of walking patterns.

Reliability of a computer-aided color-coded video-based system for clinical assessment of the foot

There is a need for a user-friendly system that can provide quick and reliable assessment of foot disorders. The study described in this report was undertaken to determine the inter-rater and intra-rater reliability of a computer-aided, color-coded, video-based system developed for the assessment of foot alignment in patients with and without pes cavus deformity. Initially, 15 pedal angles were repetitively measured 7 times on 6 color-coded images of both feet, in 20 healthy adults. From the 7 repetitive measurements, the intra-class correlation was calculated and analysis of variance was used to estimate the minimum number of trials that would be necessary to identify a statistically significant difference in the measurements. To determine intra-rater reliability, 5 examiners evaluated a single set of data taken from 10 subjects. Additionally, data were obtained for 20 subjects with pes cavus deformity. The average intra-class correlation coefficient (ICC) for the anglular measurements for 2 to 7 trials was 0.98 +/- 0.06, while the intra-rater reliability was 0.90 +/- 0.14. No statistically significant differences were observed between right and left foot angles in able-bodied subjects; whereas, in the pes cavus group, 8 different angular measurements were observed to be statistically significantly different. The results of this investigation indicate that a computer-aided, color-coded, video-based system can be used to make reliable measurements of postural alignment in patients with and without pes cavus.

LEVEL OF CLINICAL EVIDENCE

5.

A comparative study of antigen and antibody detection in visceral leishmaniasis using serum and urine-based ELISA

An antigen-based ELISA system was evaluated for diagnosis of visceral leishmaniasis (VL). Urine samples from confirmed VL cases were tested by the system in comparison with urine samples from patients with non-VL infectious disease and patients with non-infectious diseases. Antigen was detected in urine of 21 out of 35 (60%) of VL cases. No cross reaction was found with samples from healthy individuals except in 3 samples from non-VL infectious diseases. Two samples from cutaneous leishmaniasis patient and one from patient with toxoplasmosis. The results obtained with the antigen-based ELISA were compared to those obtained with direct agglutination test (DAT), an antibody-based ELISA and indirect immunofluorescent antibody (IFA) revealed that the antigen-based ELISA is comparable in terms of specificity (91.2%; 95% CI=75.2-97.7%) but with a lower sensitivity (60%; 95% CI=42.2-75.6%). These results suggest that the antigen detection in urine by the noninvasive antigen-based ELISA system might offer a useful method for diagnosis of VL.

Bracing has no effect on standing balance in females with adolescent idiopathic scoliosis

BACKGROUND

Since trunk morphology and curve types were reported to affect standing in adolescent idiopathic scoliosis (AIS), it is reasonable to assume that bracing could perturb standing balance in this population. The objective here was to use time- and frequency-domain analyses to test if the Boston brace affects balance in AIS.

MATERIAL/METHODS

Fifteen AIS girls were fitted with a Boston brace. At the four-month follow-up, standing balance was assessed using center of pressure (COP) displacements measured from a force plate. The subjects were tested with and without the brace.

RESULTS

The mean position of the COP and the sway area were similar with and without the brace. Though the first peak in the power spectra was not statistically significant, the second peak was statistically smaller with the brace in the antero-posterior direction (p=0.012) and larger along the medio-lateral axis (p=0.022). In the antero-posterior direction there was a statistically significant shift towards higher mean (p=0.012) and median (p=0.003) frequencies with the brace, whereas no difference was noted in the medio-lateral direction. Time-domain parameters did not prove useful in differentiating between the in- and out-of-brace conditions in AIS individuals. The second peak in the power spectra could be associated with an inverse double-pendulum motion.

CONCLUSIONS

The time-dependent parameters used in this study did not prove useful in differentiating between in-brace and out-of-brace conditions. Spectral analysis highlighted increased stiffness in the antero-posterior direction and less control in the medio-lateral axis in standing balance between in-brace and out-of-brace conditions in AIS.

Isolation and structure elucidation of a new potent anti-neoplastic diterpene from Dendrostellera lessertii

Two diterpene esters were isolated from Dendrostellera lessertii. These compounds were identified as compound I (12-O-benzoyl-3,5-hydroxy-6,7-epoxy-resiniferonol-9,13,14-orthobenzoate) and compound 11 (12-O-benzoyl-5-hydroxy-6,7-epoxy-resiniferonol-9,13,14-orthodecanoate). Cytotoxicity evaluation of these two compounds, using seven different cancerous cell lines, indicated that compound I with IC50 of 5-25 nmol, is 2.5 times more active than compound II. Using flow cytometry technique, it was found that treatment of the most responsive cells (K562) with compound I inhibited the progression of cells through G1 phase by almost 20% compared to the untreated cells.

Effect of Body Morphology on Standing Balance in Adolescent Idiopathic Scoliosis

OBJECTIVES

The objective of this study was to determine the effect of body somatotype on standing balance in girls with adolescent idiopathic scoliosis (AIS) who are under observation but not wearing a body brace.

DESIGN

In all, 74 girls participated in this study to form the able-bodied (n = 36) and the AIS (n = 38) groups, having an average age of 13 yrs. Quiet standing balance was tested using a force platform. Afterward, subjects in each group were divided according to their dominant body somatotype, namely endomorphs (fatness), mesomorphs (muscular), or endomorphic ectomorphs (lean).

RESULTS

The center of pressure measured in the anteroposterior position was closer to the heels for the AIS ectomorphic group by approximately 14 mm (P = 0.00497). Only the AIS mesomorphic group displayed a statistically significant 12-mm shift to the right in their center of pressure (P = 0.01211) compared with the able-bodied girls of the same morphotype. In the endomorphic group, the sway area was statistically higher for the scoliotic subjects (P = 0.00839). The distances traveled by the AIS subjects were all statistically longer for all three body morphologic somatotypes.

CONCLUSION

Different postural responses seem to be dependent on body somatotypes. The endomorphic AIS girls had a larger sway area than their able-bodied counterparts while maintaining a similar center of pressure position. The AIS ectomorphic girls had a tendency to lean further back than a comparable able-bodied group. This could be emphasizing a hypokyphotic trunk attitude and increasing the risk of spinal deformity progression. The AIS mesomorphic subjects characterized by a large muscular and bony structure had a tendency to position their center of mass more to their right, indicating less postural adaptability and a stiffer trunk.

Simultaneous, bilateral, and three-dimensional gait analysis of elderly people without impairments

OBJECTIVE

The main objectives of this study were to determine if the right and left lower limbs in the gait of elderly people developed similar muscle moment and power patterns and to determine whether their associated mechanical energies were different during two consecutive gait cycles.

DESIGN

A total of 18 able-bodied male subjects aged 71 +/- 6.8 yrs participated in this study. Data were collected using three Optotrak position sensors and two AMTI force platforms.

RESULTS

The peak muscle powers were very similar in the sagittal plane and reflected gait symmetry, except for greater and significant differences produced by the hip extensors. Differences in the frontal and transverse planes were mainly attributed to the actions taken by the muscles, leading the lower limbs to compensate and to dynamically balance and propel the body forward during two consecutive gait cycles. In terms of mechanical energy, 13% greater positive work was done in the left limb and was associated with asymmetrical behavior of the lower limbs to propel the body forward. The total negative work was similar for both limbs, and substantial work was done in the frontal plane by the hip, indicating the role of muscle activity in this plane to control the pelvis and trunk against gravitational forces.

CONCLUSIONS

In addition to the importance of a balance-control function in the gait of healthy, elderly subjects, muscle activity made an important contribution to propelling the body forward. Gait asymmetry in elderly subjects seems to be related to different degrees of energy generated by the lower limbs for the propulsion function, whereas both limbs contribute similarly to the balance-control function.

Synthesis and calcium antagonist activity of 1,4-dihydropyridines containing phenylaminoimidazolyl substituents

Alkyl ester analogues of nifedipine, in which the ortho-nitrophenyl group at position 4 is replaced by 2-methylthio-1-phenylamino-5-imidazolyl substituent, were synthesized and evaluated as calcium-channel antagonists using the high K(+) contraction of guinea-pig ileal longitudinal smooth muscle. The results for the symmetrical esters showed that in the series of alkyl esters increasing the length of methylene chain in C-3 and C-5 ester substituents for more than two methylene units decreases activity. In the phenylalkyl ester series increasing the length of methylene chain also decreases activity. The results demonstrate that most of the compounds had similar activity to the reference drug nifedipine. In addition, two compounds, 5b and 5f were more active than the nifedipine.

Local or global asymmetry in gait of people without impairments

Using two consecutive gait cycles, simultaneous and bilateral kinetic gait data, the main objectives of this study were (a) to identify the main functional roles of ankle, knee and hip extensors/flexors, and (b) to determine whether the action taken by these muscle groups appears to be symmetric or not. Gait of our able-bodied subjects appears to be asymmetric with significant differences noted between each two corresponding peak muscle moment values. Using principal component analysis (PCA) as a curve structure detection method, task discrepancies were recognized when comparisons were made between each two corresponding representative moment curves at each joint (local asymmetry). Muscle moment behaved symmetrically when the right limb representative curve was compared to its corresponding principal component (PC) at the contralateral limb. Gait of able-bodied subjects appears to be symmetric, while control and propulsion were recognized as two major roles of the extensors and flexors (global gait asymmetry). Symmetrical behavior of the lower limbs should be considered a consequence of local asymmetry which indicates different levels of within and between muscle activities developed at each joint during gait cycles.

Continuous curve registration as an intertrial gait variability reduction technique

Timing in peak values shifts slightly between gait trials. When gait data are averaged, part of the standard deviation could be associated with this intertrial variability unless normalization is carried out beforehand. The objective of this study was to determine how continuous curve registration, an alignment technique, can reduce intersubject variability in gait data without altering the original curve characteristics. Gait data were obtained by means of a four-camera high-speed video system synchronized to a force plate. The data for 60 gait trials were collected from 20 young, healthy subjects. Curve registration was applied to hip angular displacement, net moment, and power curves generated in the sagittal plane. Following registration, the peak values increased by an average of 1.2% (0.11 +/- 0.26 degrees) for angular displacement, and by 11.2% (0.11 +/- 0.09 W/kg) for power, while there were no changes for moments. First and second derivatives of the unregistered and registered curves did not display significant differences, and the harmonics were barely affected. Continuous curve registration would thus be an appropriate technique for application prior to any statistical analysis using able-bodied gait patterns.

Relations between standing stability and body posture parameters in adolescent idiopathic scoliosis

STUDY DESIGN

A retrospective study of standing imbalance and body posture in 71 able-bodied girls and subjects with adolescent idiopathic scoliosis was conducted.

OBJECTIVE

To test the hypothesis that postural parameters are related to standing stability parameters.

SUMMARY OF BACKGROUND DATA

Spinal deformity not only modifies the shape of the trunk, but also changes the relations between body segments affecting posture in scoliotic children. These postural adaptations to the scoliotic curve progression could be linked in part to increased body sway in upright standing. This has not yet been related to specific postural parameters involving the head, trunk, and pelvis in nontreated idiopathic scoliosis.

METHODS

The head, trunk, and pelvis orientations of each subject were measured by a Flock of Bird system. An AMTI force platform was used to assess quiet standing stability and to monitor the position and displacement of the center of pressure (COP). The center of mass (COM) excursion was estimated from a biomechanical model using force plate information only. Analyses of variance (ANOVAS) were performed to determine the statistical differences between the scoliotic and nonscoliotic subjects, and backward stepwise multiple regression analyses were performed to identify any correlation between measures of quiet standing stability and body postural parameters

RESULTS

The scoliotic group was characterized by a decrease in standing stability. There was an increase in the sway areas measured by the variations of the COP and COM. From the backward stepwise multiple regression analysis, it appears that for the able-bodied girls, the body posture parameters were correlated only with the mean anteroposterior center of pressure (COP(AP)) position. For the scoliotic group, the sway areas and the mean position of the centers of pressure and the COP(AP)-COM(AP) were correlated significantly with body posture parameters. The higher COP-COM differences for the scoliotic group were attributed to a greater neuromuscular demand to maintain standing balance. The coefficients of correlation of the multiple regression analyses ranged from 0.64 to 0.85 for the nonscoliotic group and from 0.55 to 0.72 for the scoliotic group.

CONCLUSIONS

The use of backward stepwise multiple correlations highlighted the interaction between several body parameters and their relation to standing stability in both able-bodied girls and scoliotic subjects. The scoliotic group displayed a much larger number of correlations between standing stability and body posture parameters than the nonscoliotic group. Standing imbalance was related to altered body posture parameters measured in the frontal and horizontal planes only. Although the correlation coefficients were relatively high, factors other than body posture parameters appeared related to standing imbalance in adolescent idiopathic scoliosis. These findings support the concept of either a primary or a secondary dysfunction in the postural regulation system of scoliotic subjects.