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Background: Injury risk in soccer varies by sex. Female soccer players face a greater risk of anterior cruciate ligament injury and patellofemoral problems, while male players are more likely to experience sports hernia symptoms. The purpose of this study was to test the hypothesis that females have different lower-extremity alignment and muscle activation patterns than males during the soccer kick.Methods: Thirteen male and twelve female college soccer players underwent three-dimensional motion analysis and electromyography of seven muscles (iliacus, gluteus maximus, gluteus medius, vastus lateralis, vastus medialis, hamstrings, and gastrocnemius) in both the kicking and the supporting lower extremity and two additional muscles (hip adductors and tibialis anterior) in the kicking limb only. Five instep and five side-foot kicks were recorded for each player. Muscle activation was recorded as a percentage of maximum voluntary isometric contraction.Results: The male soccer players had significantly higher mean muscle activation than their female counterparts with respect to the iliacus in the kicking limb (123% compared with 34% of maximal voluntary isometric contraction; p = 0.0007) and the gluteus medius (124% compared with 55%; p = 0.005) and vastus medialis muscles (139% compared with 69%; p = 0.002) in the supporting limb. The supporting limb reached significantly greater mean hip adduction during the stance phase of the kick in the females compared with that in the males (15 degrees and 10 degrees, respectively; p = 0.006).Conclusions: Differences between the sexes in lower extremity alignment and muscle activation occur during the soccer instep and side-foot kicks. Decreased activation of the hip abductors and greater hip adduction in the supporting limb during the soccer kick in female athletes may be associated with their increased risk for anterior cruciate ligament injury. [ABSTRACT FROM AUTHOR]

Hydrocarbon measurements have been made on dissolved, suspended particulate and sediment samples collected in 1987, 1993 and 1994 from the Mackenzie River delta and shelf and in 1993 from 10 smaller Northwest Territories and Nunavut rivers that drain into the Canadian Archipelago or Hudson''s Bay. Suspended particulate samples from all rivers have a resolved higher alkane pattern with a well-defined odd–even predominance consistent with a major source in terrestrial, vascular plant material. Particulate samples from the 10 smaller rivers have alkane concentrations that are similar to the Mackenzie River during summer, but PAH (polycyclic aromatic hydrocarbon) concentrations are approximately 10 times lower for the parent PAHs and 100 times lower for alkyl PAHs. PAHs on suspended particulate from the Mackenzie River exhibit a uniform composition typical of mature petrogenic sources, while PAHs in the smaller rivers are typical of combustion. The virtual absence of petrogenic PAHs in the smaller rivers is the single most important difference between these and the Mackenzie River. During summer the alkane and PAH composition of suspended particulate in the Mackenzie River is sufficiently homogenous to estimate directly the hydrocarbon load from the particulate load. Mackenzie River particulates and sediments have the hopane and sterane ratios characteristic of immature bitumens, shales or coals from the Devonian Canol formation that outcrops in the lower Mackenzie River valley. The erosion of organic-rich rocks from this formation is likely the source of the refractory petrogenic material found in the Mackenzie River delta and shelf. Data are insufficient to determine whether the petrogenic lower alkanes and PAHs have the same source or whether more mature petroleum also contributes. Because sediment samples (suspended and bed) from the Mackenzie delta have natural PAH concentrations that exceed the level where adverse biological effects are expected to occur, there is an urgent need to establish whether these petroleum-derived PAHs are bioavailable and if they are inducing effects in bottom fish and other biota. [Copyright &y& Elsevier]