Factors Associated With Cocaine Use at 17 and 20 Years Old: A Longitudinal Analysis of a Nationally Representative Cohort.

Purpose: Despite growing concerns about trends in cocaine use, there is a shortage of longitudinal research that prospectively examines risk and protective factors associated with cocaine initiation and use in general youth populations. This study addresses this gap.

Methods: Growing Up in Ireland is a nationally representative cohort.

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Background: Cannabis is the most commonly used illicit substance in Ireland and globally. It is most likely to be used in adolescence, a period of biopsychosocial vulnerability to maladaptive behaviours. This study aims to investigate the risk and protective factors for cannabis use among adolescents.

An Evaluation of the Effect of App-Based Exercise Prescription Using Reinforcement Learning on Satisfaction and Exercise Intensity: Randomized Crossover Trial.

Background: The increasing prevalence of sedentary lifestyles has prompted the development of innovative public health interventions, such as smartphone apps that deliver personalized exercise programs. The widespread availability of mobile technologies (eg, smartphone apps and wearable activity trackers) provides a cost-effective, scalable way to remotely deliver personalized exercise programs to users. Using machine learning (ML), specifically reinforcement learning (RL), may enhance user engagement and effectiveness of these programs by tailoring them to individual preferences and needs.

The Training Intensity Distribution of Marathon Runners Across Performance Levels.

Background: The training characteristics and training intensity distribution (TID) of elite athletes have been extensively studied, but a comprehensive analysis of the TID across runners from different performance levels is lacking.

Methods: Training sessions from the 16 weeks preceding 151,813 marathons completed by 119,452 runners were analysed. The TID was quantified using a three-zone approach (Z1, Z2 and Z3), where critical speed defined the boundary between Z2 and Z3, and the transition between Z1 and Z2 was assumed to occur at 82.