Ключевые слова: 20s, 60s, action, activity, aged, athletic, ball, caucasian, competition, concentration, court, double, doubles, effort, elderly, european, exercise, female, fitness, game, hobby, motivation, net, outdoor, play, player, playground, playing, practicing, racket, racquet, recreation, serve, serving, skill, sport, sporty, technique, tournament, training, vitality, winning, woman, workout, young, youth,