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This study compared the efficacy of linear, non-linear and differential methods on variables related to ACL injury risk of a side-step cutting task in male and female basketball players. Thirty males and thirty females practiced basketball skills in sixty 90-minute sessions across 5 months. Ten players trained in each of the LP, NLP and DL female/male groups separately. Before and after the intervention, each player was tested on a side-step cutting task. A repeated 3 × 2 × 2 factorial ANOVA with repeated measures was performed for each biomechanical variable. Variables (trunk, hip, and knee flexion angle, knee valgus angle, ankle dorsiflexion angle, hip, knee, and ankle ROM, peak VGRF and knee extension/flexion, knee moment and ankle dorsiflexion moment) all revealed significant test by group interactions (P < 0.05) but no significant group by sex interactions (P > 0.05). In both sex, biomechanical changes were better in the NLP, followed by the DL and LP. It is argued that the advantage of the NLP method results from increased exploration of movement solutions induced by the manipulation of task constraints. Therefore, according to the NLP, it is possible to manipulate the constraints without feedback and the model/pattern can keep the athlete away from possible risks.

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Work-related musculoskeletal disorders (WMSDs) are among the most common disorders in any work sector and industry. Ergonomic risk assessment can reduce the risk of WMSDs. Motion capture that can provide accurate and real-time quantitative data has been widely used as a tool for ergonomic risk assessment. However, most ergonomic risk assessments that use motion capture still depend on the traditional ergonomic risk assessment method, focusing on qualitative data. Therefore, this article aims to provide a view on the ergonomic risk assessment and apply current motion capture technology to understand classical mechanics of physics that include velocity, acceleration, force, and momentum in ergonomic risk assessment. This review suggests that using motion capture technologies with kinetic and kinematic variables, such as velocity, acceleration, and force, can help avoid inconsistency and develop more reliable results in ergonomic risk assessment. Most studies related to the physical measurement conducted with motion capture prefer to use non-optical motion capture because it is a low-cost system and simple experimental setup. However, the present review reveals that optical motion capture can provide more accurate data.

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The aim of this study was to characterize the turning phase during a modified 505 test. Forty collegiate basketball students, divided into faster and slower performers and high-playing-level and low-playing-level groups, were evaluated for the force-time characteristics (braking and/or propulsive phase) of the penultimate foot contact (PFC), final foot contact (FFC), and first accelerating foot contact (AFC), and for completion time and approach velocity. Based on the composition of the AFC, trials were classified as braking/propulsive or only propulsive. Regression analysis for the prediction of completion time was performed. The AFC contributed to reacceleration through shorter contact times and step length, and lower braking force production (p < 0.05). Faster performers and the high-playing-level group demonstrated (p < 0.05): lower completion times, higher approach velocities, longer steps length in the PFC and FFC, greater braking forces and impulses in the PFC; greater braking and propulsive forces, braking impulses, lower contact times in the FFC; greater braking and propulsive horizontal forces, horizontal impulses, lower contact times and vertical impulses in the AFC. Kinetic variables from only the FFC and AFC and approach velocity predicted 75% (braking/propulsive trials) and 76.2% (only-propulsive trials) of completion times. The characterization of the turning phase demonstrated the specific contribution of each foot contact and the possible implications for training prescription.

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The aim of this study was to analyse changes in gait variability and symmetry with increasing speed in race walkers. Eighteen international athletes race walked on an instrumented treadmill at speeds of 11, 12, 13 and 14 km·h-1 in a randomised order for 3 min each. Spatiotemporal and ground reaction force data were recorded for 30 s at each speed. Gait variability was measured using median absolute deviation and inter-leg symmetry was measured using the symmetry angle. There was an overall effect of speed on all absolute values except push-off force, but symmetry and variability (except flight time) did not change with increased speed, step length and step frequency. Most athletes were asymmetrical for at least one variable, but none was asymmetrical for more than half of the variables measured. Therefore, being asymmetrical or having higher variability (<5%) in a few variables is normal. Taking all findings together, practitioners should exercise caution when deciding on the need for corrective interventions and should not be concerned that increasing gait speed could increase injury risk through changes to athletes' asymmetry. Race walking coaches should test at competition speeds to ensure that flight times, and any variability or asymmetry, are measured appropriately.

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OBJECTIVES: Abnormalities in the timing and course of spermatozoa capacitation and hyperactivation underlie common pathologies related to male infertility. Recent data shows that low frequency electromagnetic waves may influence cell membrane potential and permeability. It is therefore possible that low frequency electromagnetic waves could affect the maturation and motility processes of spermatozoa. The 43-kHz wave generator was used for modeling the impact of environmental exposure to low frequency electromagnetic radiation on human sperm. MATERIAL AND METHODS: Sperm samples were gathered from 103 fertile, healthy men aged 25-30 years old and performed computer-assisted sperm analysis. After initial examination, each participant's semen sample was divided into 2 aliquots (control and experimental) and placed in separate automated incubators. The samples constituting the experimental group were placed into the exposure system that emitted 43-kHz electromagnetic waves. Sperm motility was assessed at 3 h, 12 h and 24 h. RESULTS: Exposure to a 43-kHz radio frequency increased the percentage of sperm in progressive motility by up to 5.8% and the velocity of said sperm by up to 2 µm/s. Moreover, the total number of hyperactivated spermatozoa was significantly increased in the semen exposed to the electromagnetic signal. CONCLUSIONS: In vivo environmental exposure to 43-kHz waves may promote the development of infertility related to premature capacitation outside of the vaginal tract. Exposing semen to this particular frequency may also boost the capacitation and hyperactivation of spermatozoa in vitro, prior to conducting assisted reproductive therapies.Int J Occup Med Environ Health 2018;31(6):723-739.

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OBJECTIVE: To observe the kinetic change that reflects joint loading in different planes during stair climbing in knee osteoarthritis (KOA) after electroacupuncture (EA) by three-dimensional motion analysis, so as to provide reference for its biomechanical mechanism treated with acupuncture. METHODS: Forty KOA patients, in accordance with the random number table, were assigned into an observation group and a control group, 20 cases in each one and finally 18 cases completed. Acupoints in the observation group were Neixiyan (EX-LE 4), Dubi (ST 35), Yanglingquan (GB 34), Yinlingquan (SP 9), Xuehai (SP 10), Liangqiu (ST 34) and Zusanli (ST 36); points in the control groups were located about 2 cm next to the above acupoints with shallow acupuncture. EA was connected at Neixiyan (EX-LE 4) and Yinlingquan (SP 9), Liangqiu (ST 34) and Yanglingquan (GB 34). The frequency was 2 Hz with continuous wave in the observation group and there was no current in the control group for the corresponding points. All the treatment was given for 3 weeks, totally 11 times. Climbing stairs gait was measured before and after treatment. Velocities and kinetic parameters during ascending and descending stairs were analyzed, including flexion and extension peak torques of hip, knee, ankle on the vertical plane, external knee adduction moment on the coronal plane. RESULTS: After treatment in the observation group, velocities during ascending and descending stairs significantly increased (P<0.05, P<0.01); maximal ankle plantar flexor moments during ascending and descending stairs and the second peak external knee adduction moment (PEKAM2) during ascending stairs significantly increased (P<0.05, P<0.01). After treatment in the control group, the first peak external knee adduction moment (PEKAM1) and PEKAM2 during descending stairs were less than those before treatment (P<0.05, P<0.01). In the observation group, the difference value (DV) of velocity before and after treatment was positively correlated to DV in the torque of ankle plantar flexors during ascending stairs in the observation group (r=0.598，P<0.01). Excluding the impact of velocity, the DV of the maximal torque of ankle plantar flexors during ascending stairs didn't show difference in the observation group (P>0.05). CONCLUSION: EA can increase the velocities of ascending and descending stairs of KOA patients. It improves the loading capacity of knee joint on both sagittal and coronary planes. But its effect during ascending may be correlated with the increase of velocity. The mechanism of different effects between EA and minimal acupuncture on joint moments is still unclear and warrants further study.

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<p><b>OBJECTIVE</b>To observe the kinetic change that reflects joint loading in different planes during stair climbing in knee osteoarthritis (KOA) after electroacupuncture (EA) by three-dimensional motion analysis, so as to provide reference for its biomechanical mechanism treated with acupuncture.</p><p><b>METHODS</b>Forty KOA patients, in accordance with the random number table, were assigned into an observation group and a control group, 20 cases in each one and finally 18 cases completed. Acupoints in the observation group were Neixiyan (EX-LE 4), Dubi (ST 35), Yanglingquan (GB 34), Yinlingquan (SP 9), Xuehai (SP 10), Liangqiu (ST 34) and Zusanli (ST 36); points in the control groups were located about 2 cm next to the above acupoints with shallow acupuncture. EA was connected at Neixiyan (EX-LE 4) and Yinlingquan (SP 9), Liangqiu (ST 34) and Yanglingquan (GB 34). The frequency was 2 Hz with continuous wave in the observation group and there was no current in the control group for the corresponding points. All the treatment was given for 3 weeks, totally 11 times. Climbing stairs gait was measured before and after treatment. Velocities and kinetic parameters during ascending and descending stairs were analyzed, including flexion and extension peak torques of hip, knee, ankle on the vertical plane, external knee adduction moment on the coronal plane.</p><p><b>RESULTS</b>After treatment in the observation group, velocities during ascending and descending stairs significantly increased (<0.05,<0.01); maximal ankle plantar flexor moments during ascending and descending stairs and the second peak external knee adduction moment (PEKAM2) during ascending stairs significantly increased (<0.05,<0.01). After treatment in the control group, the first peak external knee adduction moment (PEKAM1) and PEKAM2 during descending stairs were less than those before treatment (<0.05,<0.01). In the observation group, the difference value (DV) of velocity before and after treatment was positively correlated to DV in the torque of ankle plantar flexors during ascending stairs in the observation group (=0.598，<0.01). Excluding the impact of velocity, the DV of the maximal torque of ankle plantar flexors during ascending stairs didn't show difference in the observation group (>0.05).</p><p><b>CONCLUSION</b>EA can increase the velocities of ascending and descending stairs of KOA patients. It improves the loading capacity of knee joint on both sagittal and coronary planes. But its effect during ascending may be correlated with the increase of velocity. The mechanism of different effects between EA and minimal acupuncture on joint moments is still unclear and warrants further study.</p>

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BACKGROUND: Required Coefficient of Friction (RCOF) is one of the most critical gait parameters associated to the occurrence of slipping in individuals affected by neurological disorders characterized by balance impairments. This study aims to calculate RCOF in people with Multiple Sclerosis (MS) on the basis of three-dimensional Gait Analysis (GA) data. METHODS: This study enrolls 22 people with MS (pwMS) who were characterized by an Expanded Disability Status Score in the range 1.5-6 and 10 healthy controls (HC). All participants underwent to three-dimensional GA from which we extracted kinematic and kinetic data (i.e. the Ground Reaction Forces, GRF, and joint moments and powers in the sagittal plane). RCOF was calculated as the ratio of the shear to normal GRF components during the stance phase of gait cycle, and normalized by the walking velocity. Thus, the following variables were extracted: first peak (named P1COF), valley (named V1COF), and second peak (named P2COF) in RCOF curve; also computating the maximum ankle dorsi-plantarflexion moment (MOMmax) and the maximum ankle joint power (PWRmax). RESULTS: Our data revealed that P2COF results are significantly lower in pwMS when compared to HC (p=0.043; Z=-2.025). In pwMS, the study found a moderate, positive correlation between V1COF and MOMmax (r=0.558; p<0.001) and a moderate, positive correlation between EDSS score and MOMmax (rho=0.622; p=0.001). While, in HC group, the study detected a moderate positive correlation between P1COF and MOM max (r=0.636; p=0.008). CONCLUSION: Friction during mid stance and push off phases is critically important to determine whether the frictional capabilities of foot/floor interface are sufficient to prevent slips in pwMS. The impaired ankle moment in MS group causes increased P2COF in comparison to HC, increasing the risk of slipping in the critical phase of transmission of the developed forces to kinematic chain. Also, the correlation analysis among RCOF values and kinetic variables describe the interplay between V1COF and MOMmax: the higher V1COF is, the higher is MOMmax; and the different correlation the study found between COF and kinetic parameters in MS and HC group highlightes the different gait patterns of the two classes of subjects.

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There are growing concerns about how electromagnetic waves (EMW) emitted from mobile phones affect human spermatozoa. Several experiments have suggested harmful effects of EMW on human sperm quality, motility, velocity, or the deoxyribonucleic acid (DNA) of spermatozoa. In this study, we analyzed the effects on human spermatozoa (sperm motility and kinetic variables) induced by 1 h of exposure to 1950 MHz Wideband Code Division Multiple Access (W-CDMA)-like EMW with specific absorption rates of either 2.0 or 6.0 W/kg, using a computer-assisted sperm analyzer system. We also measured the percentage of 8-hydroxy-2'-deoxyguanosine (8-OHdG) positive spermatozoa with flow cytometry to evaluate damage to DNA. No significant differences were observed between the EMW exposure and the sham exposure in sperm motility, kinetic variables, or 8-OHdG levels. We conclude that W-CDMA-like exposure for 1 h under temperature-controlled conditions has no detectable effect on normal human spermatozoa. Differences in exposure conditions, humidity, temperature control, baseline sperm characteristics, and age of donors may explain inconsistency of our results with several previous studies. Bioelectromagnetics. 37:373-381, 2016. © 2016 Wiley Periodicals, Inc.

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