Perception and reality : meeting Australia’s physical activity guidelines for 12-18 year olds

Governments regularly publish empirically derived minimum physical activity (PA) guidelines for youth, in response to the ongoing trend of youth physical inactivity. The purpose of this investigation was to explore parents’ awareness of the national PA guidelines for youth, and adolescents’ and their parents’ perceptions of adolescent PA, and compare these to self-reported adolescent PA. A total of 115 adolescents (aged 12-14) and their parents completed questionnaire assessments. Parents responded to questions concerning their awareness of the national PA guidelines, and whether they believed their child to be sufficiently active. Adolescents completed the International Physical Activity Questionnaire for Adolescents, and questions concerning their perceived level of PA. Adolescents were deemed sufficiently active if they participated in an average of at least 60 minutes of moderate-to-vigorous PA each day. Overall, 104 (90.4%) adolescents and their parents had complete data sets and were included in the analysis. Of the 45 (43.3%) sufficiently and 59 (56.7%) insufficiently active adolescents, 42 (93%) and 41 (69.5%) respectively believed that they were active enough for good general health. Additionally, 41 (91.1%) parents of active and 44 (74.6%) parents of inactive adolescents either agreed or strongly agreed that their child participates in sufficient PA for good general health. Twenty-four (53.3%) parents of active adolescents were unaware of the national PA guidelines, with 10 (22.2%) neither aware or unaware, and 11 (24.4%) aware. Similar results were found for the parents of inactive adolescents with 31 (52.5%) unaware, 17 (28.8%) neither aware or unaware, and 11 (18.6%) aware. These results suggest that the youth PA guidelines are being inadequately received by both adolescents, and their parents. Opportunities to effectively communicate these guidelines such as embedment in curriculum for adolescents, or the dissemination of materials for parents, should be maximised by appropriate authorities.

A novel device using the Nordic hamstring exercise to assess eccentric knee flexors strength : a reliability and retrospective injury study

STUDY DESIGN: Reliability and case-control injury study. OBJECTIVES: 1) To determine if a novel device, designed to measure eccentric knee flexors strength via the Nordic hamstring exercise (NHE), displays acceptable test-retest reliability; 2) to determine normative values for eccentric knee flexors strength derived from the device in individuals without a history of hamstring strain injury (HSI) and; 3) to determine if the device could detect weakness in elite athletes with a previous history of unilateral HSI. BACKGROUND: HSIs and reinjuries are the most common cause of lost playing time in a number of sports. Eccentric knee flexors weakness is a major modifiable risk factor for future HSIs, however there is a lack of easily accessible equipment to assess this strength quality. METHODS: Thirty recreationally active males without a history of HSI completed NHEs on the device on 2 separate occasions. Intraclass correlation coefficients (ICCs), typical error (TE), typical error as a co-efficient of variation (%TE), and minimum detectable change at a 95% confidence interval (MDC95) were calculated. Normative strength data were determined using the most reliable measurement. An additional 20 elite athletes with a unilateral history of HSI within the previous 12 months performed NHEs on the device to determine if residual eccentric muscle weakness existed in the previously injured limb. RESULTS: The device displayed high to moderate reliability (ICC = 0.83 to 0.90; TE = 21.7 N to 27.5 N; %TE = 5.8 to 8.5; MDC95 = 76.2 to 60.1 N). Mean±SD normative eccentric flexors strength, based on the uninjured group, was 344.7 ± 61.1 N for the left and 361.2 ± 65.1 N for the right side. The previously injured limbs were 15% weaker than the contralateral uninjured limbs (mean difference = 50.3 N; 95% CI = 25.7 to 74.9N; P < .01), 15% weaker than the normative left limb data (mean difference = 50.0 N; 95% CI = 1.4 to 98.5 N; P = .04) and 18% weaker than the normative right limb data (mean difference = 66.5 N; 95% CI = 18.0 to 115.1 N; P < .01). CONCLUSIONS: The experimental device offers a reliable method to determine eccentric knee flexors strength and strength asymmetry and revealed residual weakness in previously injured elite athletes.