Effect of long-term intake of α-lactalbumin on menstruation-related symptoms and quality of life in healthy Japanese women: a randomized, double-blind, placebo-controlled study.

Adolescence, defined by the World Health Organization as the period between 10 and 19 years of age, is a critical developmental stage during which lifestyle habits are formed that often persist into adulthood. Physical activity (PA) plays a fundamental role in healthy adolescent development, supporting cardiometabolic health, bone strength, mental wellbeing, and the prevention of future non-communicable diseases. Today’s adolescents are more engaged with digital devices than any earlier generation. Smartphones, tablets, smartwatches, and fitness trackers have become ubiquitous, with ownership rates exceeding 80% in many high-income countries and rising rapidly in lower-resource settings. However, the prevalence of physical inactivity is still increasing. Current data indicates that 81% of adolescents worldwide fail to achieve the suggested levels of physical activity (, ). This widespread inactivity leads to serious health risks, including lower cardiometabolic fitness, weakened bone health, higher body fat, and declining mental well-being, particularly affecting youth in underprivileged regions and ethnic minority groups (, ). Physical inactivity is also a major modifiable risk factor for noncommunicable diseases, contributing to an estimated 1.6 million deaths annually worldwide (). Demographic disparities are alarming: only 22% of adolescents adhere to PA recommendations, and just 2.9% of Mexican American girls meet the daily target of 60 min of moderate-to-vigorous physical activity ().