Lower limb joint kinetics in the starting blocks and first stance in athletic sprinting

The aim of this study was to examine lower limb joint kinetics during the block and first stance phases in athletic sprinting. Ten male sprinters (100 m PB, 10.50 ± 0.27 s) performed maximal sprint starts from blocks. External force (1000 Hz) and three-dimensional kinematics (250 Hz) were recorded in both the block (utilising instrumented starting blocks) and subsequent first stance phases. Ankle, knee and hip resultant joint moment, power and work were calculated at the rear and front leg during the block phase and during first stance using inverse dynamics. Significantly (P < 0.05) greater peak moment, power and work were evident at the knee joint in the front block and during stance compared with the rear block. Ankle joint kinetic data significantly increased during stance compared with the front and rear block. The hip joint dominated leg extensor energy generation in the block phase (rear leg, 61 ± 10%; front leg, 64 ± 8%) but significantly reduced during stance (32 ± 9%), where the ankle contributed most (42 ± 6%). The current study provides novel insight into sprint start biomechanics and the contribution of the lower limb joints towards leg extensor energy generation.     

Land of confusion: unpacking the relationship between physical activity and well-being in individuals living with osteoporosis

Whether physical activity is linked with improvements in well-being in individuals living with osteoporosis remains a source of debate within the literature. The purpose of this review is to synthesize relevant literature to more fully address the relationship between physical activity and well-being in individuals living with osteoporosis. Guided by study inclusion criteria, a total of 17 quantitative studies were coded for review. Considerable heterogeneity was found between studies when examining the well-being instrumentation and physical activity characteristics used by study authors. A central finding was that physical activity is associated with increased well-being across the bulk of existing studies retained for analysis, with benefits noted particularly for markers linked to physical functioning. This review further highlights how decisions made by researchers have implications for study conclusions and can render any synthesis of this literature a challenge. As such, recommendations for future studies are advanced that span issues linked to the measurement and conceptualization of well-being and physical activity and the analytic decisions made by researchers. Finally, heightened attention to the mechanisms through which physical activity may be linked with well-being outcomes is needed. Given the importance of well-being outcomes, researchers are encouraged to adopt these recommendations in an effort to advance the literature.     

Mid-flight lateral trunk bending increased ipsilateral leg loading during landing: a center of mass analysis

Increased lateral trunk bending to the injured side has been observed when ACL injuries occur. The purpose was to quantify the effect of mid-flight lateral trunk bending on center of mass (COM) positions and subsequent landing mechanics during a jump-landing task. Forty-one recreational athletes performed a jump-landing task with or without mid-flight lateral trunk bending. When the left and right trunk bending conditions were compared with the no trunk bending condition, participants moved the COM of the upper body to the bending direction, while the COM of the pelvis, ipsilateral leg, and contralateral leg moved away from the bending direction relative to the whole body COM. Participants demonstrated increased peak vertical ground reaction forces (VGRF) and knee valgus and internal rotation angles at peak VGRF for the ipsilateral leg, but decreased peak VGRF and knee internal rotation angles at peak VGRF and increased knee varus angles at peak VGRF for the contralateral leg. Mid-flight lateral trunk resulted in an asymmetric landing pattern associated with increased ACL loading for the ipsilateral leg. The findings may help to understand altered trunk motion during ACL injury events and the discrepancy in ACL injuries related to limb dominance in badminton and volleyball.     

Parental sport achievement and the development of athlete expertise

This study sought to examine how parental sport involvement and attainment were related to the eventual level of competitive sport attained by their children. Athletes (n?=?229) were divided into three skill level groups (elite: n?=?139; pre-elite: n?=?33; non-elite: n?=?57), based on the peak competition level achieved in their career, which were compared using chi-squares tests of independence and analyses of variance according to parents sport characteristics provided through the Developmental History of Athletes Questionnaire. Parental recreational and competitive sport participation was overrepresented among elite athletes, as were parents who reached an elite level of sport themselves. Results were found to differ according to parent sex, with athlete skill level significantly related to the sport participation and skill level of fathers, but not mothers. Results suggest parental sport experiences at different levels of competition influence the development of athletes, although these relationships are subject to many factors.     

A critique of the expectancy formula approach: Beating a dead horse?

The expectancy and severe discrepancy formulas, like those originally considered by the US. Office of Education (1976), provide the oldest but least defensible method of quantifying academic discrepancy. A logical and mathematical analysis reveals that all variations of this approach have several major weaknesses. First, the expectancy formulas themselves are predicated upon the very questionable assumption that achievement follows a straight line growth pattern, which raises questions about the accuracy of the resulting severe discrepancy values. Second, when discrepancy values are obtained by multiplying the expected values by a fractional constant, the approach is necessarily biased in the direction of applying a more stringent underachievement criterion for older and brighter children. Third, the formulas employ a grade equivalent scale that results in inconsistencies, one being that fewer arithmetic problems are identified. Finally, the expectancy approach does not consider errors in measurement or regression effects, and consequently produces serious identification errors. A variation of the expectancy approach involving a discrepancy ratio between obtained and expected achievement has the previously mentioned limitations, except the bias, and it produces scores that cannot be easily interpreted.     

Construct validity of the Illinois test of psycholinguistic abilities for a clinic population

The construct validity of the 10 primary ITPA subtests was investigated on a clinic population of 91 (66 males, 25 female) learning disabled children. Construct validity was determined by the degree to which each subtest measured discrete, independent abilities and the extent of subtest relationship to academic subject areas. Results via factor analysis and correlational analyses generally support the independence of the channel dimension, i.e., visual vs. auditory. While the process dimension, i.e., receptive, expressive, and associative, was not found to be an independent measure, the dimension of levels, i.e., representational vs. automatic, was substantiated for this clinical population. Implications of discrepancies in the channel dimension are discussed.     

The Kaufman Assessment Battery for Children (K-ABC) in the assessment of learning disabled children

The authors of the Kaufman Assessment Battery for Children (K-ABC) assert that, in addition to a discrepancy between learning potential and academic achievement, learning disability is characterized by poor sequential relative to simultaneous processing skills. The present study was designed to determine whether the K-ABC could discriminate between learning disabled and normal children on the basis of these characteristics. Forty-three LD pupils from 7 to 12 years of age and 20 normally achieving children of similar age were administered the K-ABC. Results indicated that, for both the LD and the normal children, scores on the Sequential Processing Scale were significantly lower than on the Simultaneous Processing Scale. In addition, the aiscrepancy between Simultaneous and Sequential scale scores was similarly distributed in both groups. The LD group scored lower and the normal group higher on the Achievement Scale than on the Mental Processing Composite. The results, therefore, indicated that the K-ABC differentiated LD from normal children in terms of Achievement relative to M.P.C. scores; however, it failed to reveal a unique profile pattern related to simultaneous vs. sequential processing skills for the LD group. Further analyses of the relationship between K-ABC processing scale scores and WISC-R scores, as recategorized by Bannatyne, revealed significant correlations between measures, indicating similar underlying theoretical constructs.     

Canonical variates in longitudinal achievement data

The purpose of this study was to identify factors that would explain the observed longitudinal correlations between educational measures commonly secured at the primary and middle grades. Data obtained on two samples of over 300 pupils each were subjected to canonical variate analysis. The canonical correlations and canonical loadings indicated the existence of a single dominant factor between the primary and middle grade data. This factor was interpreted as general scholastic ability, and the results were discussed along with educational implications.