Longitudinal associations of meeting the WHO physical activity guidelines and physical fitness, from preschool to childhood.

There is a well-established relationship between physical activity (PA) and physical fitness in children, being the latter an important marker for present and future health; however, there is still insufficient knowledge for the transition from the preschool age to early childhood. Therefore, this study in Swedish children aimed to investigate the estimated effect of meeting the aerobic component of the PA guidelines at 4 and/or 9 years of age on physical fitness measured at 9 years of age. PA was assessed using a wrist-worn ActiGraph accelerometer and identical data processing in 217 healthy children in Sweden (114 boys and 103 girls). Physical fitness test included cardiorespiratory (20 m shuttle run test), motor (4 × 10 m shuttle run), and muscular fitness (hand grip strength and long jump). A linear mixed model was run, investigating the interaction between meeting the PA guidelines and time (either 4 or 9 years of age) and each fitness component (at 4 and 9). Interactions by sex were also checked. Meeting the PA guidelines consistently (at 4 and 9 years) was significantly associated to better performance in physical fitness parameters for motor fitness (-0.76 s, p < 0.001) and lower body muscular fitness (+4.6 cm; p < 0.001) at 9 years. There was an interaction between meeting the PA guidelines and time point, for cardiorespiratory fitness (+4.58 laps; p < 0.001). This study shows that meeting the PA guidelines at 4 and 9 years of age is associated to higher physical fitness at 9 years of age.

Natural corollaries and recovery after acute ACL injury: the NACOX cohort study protocol.

INTRODUCTION: Anterior cruciate ligament (ACL) injury can result in joint instability, decreased functional performance, reduced physical activity and quality of life and an increased risk for post-traumatic osteoarthritis. Despite the development of new treatment techniques and extensive research, the complex and multifaceted nature of ACL injury and its consequences are yet to be fully understood. The overall aim of the NACOX study is to evaluate the natural corollaries and recovery after an ACL injury. METHODS AND ANALYSIS: The NACOX study is a multicentre prospective prognostic cohort study of patients with acute ACL injury. At seven sites in Sweden, we will include patients aged 15-40 years, within 6 weeks after primary ACL injury. Patients will complete questionnaires at multiple occasions over the 3 years following injury or the 3 years following ACL reconstruction (for participants who have surgical treatment). In addition, a subgroup of 130 patients will be followed with clinical examinations, several imaging modalities and biological samples. Data analyses will be specific to each aim. ETHICS AND DISSEMINATION: This study has been approved by the regional Ethical committee in Linköping, Sweden (Dnr 2016/44-31 and 2017/221-32). We plan to present the results at national and international conferences and in peer-reviewed scientific journals. Participants will receive a short summary of the results following completion of the study. TRIAL REGISTRATION NUMBER: NCT02931084.