training COVID-19 10 performance 9 education 8 physical activity 8 Medicine 7 assessment 6 children 6 health 6 machine learning 6 quality of life 6 Humanities 5 Psychology 5 Science: general issues 5 exercise 5 stress 5 athletes 4 biomechanics 4 fatigue 4 gamification 4 higher education 4 injury prevention 4 interval training 4 leadership 4 social media 4 strength 4 sustainability 4 virtual reality 4 Education 3 Lifestyle, sport & leisure 3