Biomechanics of elite recumbent handcycling: a case study

In the presented research, a kinematic and electromyographic study was performed on one world-class male elite handbiker (UCI class H3.2). Activity of 14 muscles of the upper body were measured with surface electromyography (EMG), and a motion analysis of the athlete’s movement was performed concurrently for different backrest positions, crank lengths, and crank heights at three power levels (130, 160 and 190 W). Kinematics in terms of elbow and wrist angle, muscular on-off timing, EMG amplitudes, and integrated EMG were calculated. Results showed that little changes occurred for kinematic parameters and changes in position led to a shift in muscular timing. However, no indication for immediate improvement to the athlete’s preferred original position could be observed.     

Kinetics of elite unilateral below-elbow amputee running

The role of the upper limbs in human locomotion and their influence on ground reaction force (GRF) have been extensively examined for walking and slow running. However, research has focused on unimpaired populations and has not evaluated high-speed running. In this study, the GRFs of an unilateral upper limb amputee athlete [missing right forearm, personal bests (PB): 400 m: 0:48.45 min, 800 m: 1:50.92 min] running at speeds of 5.4 and 8 m/s were collected using four floor-mounted force plates in a 100 m tartan track recording at 1000 Hz. The amputee athlete also performed trials with a running speed of 8 m/s wearing a weighted cuff on his impaired arm (0.5 and 1 kg, respectively). GRF data (without additional weight) were compared to those of an unimpaired athlete with similar PBs and anthropometry (age, height, weight). All data were evaluated for anterior–posterior, medial–lateral and vertical GRF as well as for stance phase (SP) duration and free moment (FM) values and a paired Student-t test (\(\alpha =5\) %) was performed on maximum and minimum values of the respective data sets comparing the left and right side of both athletes with each other, but no intersubjective comparisons were performed. The results revealed that vertical GRF showed significant differences for the impaired athlete at both running speeds comparing left and right foot, whereas the unimpaired athlete showed no significant differences in this matter at all. Medial–lateral GRF showed highly significant differences between the left and right foot of both athletes at both running speeds, whereas the results for anterior–posterior GRF and FM, however, showed ambiguous results. The trials with additional weight on the impaired limb led to significant differences for SP duration, but not for all conditions, and left–right differences did not change with additional weight. GRFs were found to differ in minimum medial–lateral GRF with no and heavy weight, maximum medial–lateral GRF within all weight conditions and maximum vertical GRF with no and heavy weight. For the FM, the overall pattern changed drastically and maximum FM showed a highly significant difference between the left and right foot, but none between the different conditions for both feet. Even though more significant asymmetries could be revealed for the impaired athlete, no general conclusion can be drawn at this point, given the limitations of the here presented study (low number of subjects available, anthropometric data of the impaired athlete could not be assessed).     

Untangling the Links among Athletic Involvement, Gender, Race, and Adolescent Academic Outcomes

Although previous research has established that high school sports participation may be associated with positive academic outcomes, the parameters of the relationship remain unclear. Using a longitudinal sample of nearly 600 Western New York adolescents, this study examined gender- and race-specific differences in the impact of two dimensions of adolescent athletic involvement ("jock" identity and athlete status) on changes in school grades and school misconduct over a two-year interval. Female and black adolescents who identified themselves as "jocks" reported lower grades than those who did not, whereas female athletes reported higher grades than female nonathletes. Jocks also reported significantly more misconduct (including skipping school, cutting classes, having someone from home called to the school for disciplinary purposes, and being sent to the principal's office) than nonjocks. Gender moderated the relationship between athlete status and school misconduct; athletic participation had a less salutary effect on misconduct for girls than for boys.     

Risk factors for speech delay of unknown origin in 3-year-old children

One hundred 3-year-olds with speech delay of unknown origin and 539 same-age peers were compared with respect to 6 variables linked to speech disorders: male sex, family history of developmental communication disorder, low maternal education, low socioeconomic status (indexed by Medicaid health insurance), African American race, and prolonged otitis media. Abnormal hearing was also examined in a subset of 279 children who had at least 2 hearing evaluations between 6 and 18 months of age. Significant odds ratios were found only for low maternal education, male sex, and positive family history; a child with all 3 factors was 7.71 times as likely to have a speech delay as a child without any of these factors.