jeunesse (1) vitamine (1) temps (durée) (1) tabagisme (1) saison (1) mode de vie (1) santé (1) effet (1) jeune (1) Genes (1) Teenagers (1) Youth (1) Vitamin D (1) Time (1) Summer (1) Spring (1) Smoking (1) Seasons (1) Regression analysis (1) Physical fitness (1) Performance (1) Percentage (1) Human beings (1) Lifestyles (1) Hemoglobin (1) Health (1) Forecasting--Study and teaching (1) Fat (1) Expression (1) Exercise (1)