title: Do Running Activities of Adolescent and Adult Tennis Players Differ During Play?
abstract: OBJECTIVE
  To investigate differences in running activities between adolescent and adult tennis players during match play. Differences between winning and losing players within each age group were also examined.
  
  
  METHODS
  Forty well-trained male players (20 adolescents, 13 ± 1 y; 20 adults, 25 ± 4 y) played a simulated singles match against an opponent of similar age and ability. Running activities were assessed using portable devices that sampled global positioning system (10 Hz) and inertial-sensor (accelerometer, gyroscope, and magnetometer; 100 Hz) data. Recorded data were examined in terms of velocity, acceleration, deceleration, metabolic power, PlayerLoad, and number of accelerations toward the net and the forehand and backhand corners.
  
  
  RESULTS
  Adult players spent more time at high velocity (≥4 m/s2), acceleration (≥4 m/s2), deceleration (≤-4 m/s2), and metabolic power (≥20 W/kg) (P ≤ .009, ES = 0.9-1.5) and performed more accelerations (≥2 m/s2) toward the backhand corner (P < .001, ES = 2.6-2.7). No differences between adolescent winning and losing players were evident overall (P ≥ .198, ES = 0.0-0.6). Adult winning players performed more accelerations (2 to <4 m/s2) toward the forehand corner (P = .026, ES = 1.2), whereas adult losing players completed more accelerations (≥2 m/s2) toward the backhand corner (P ≤ .042, ES = 0.9).
  
  
  CONCLUSIONS
  This study shows that differences in running activities between adolescent and adult tennis players exist in high-intensity measures during simulated match play. Furthermore, differences between adolescent and adult players, and also between adult winning and losing players, are present in terms of movement directions. Our findings may be helpful for coaches to design different training drills for both age groups of players.
authors.forename: Matthias W
authors.initials: MW
authors.lastname: Hoppe
authors.forename: Christian
authors.initials: C
authors.lastname: Baumgart
authors.forename: Jürgen
authors.initials: J
authors.lastname: Freiwald
mesh_terms: D000054:Acceleration; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D054874:Athletic Performance; D040362:Geographic Information Systems; D006801:Humans; D008297:Male; D005082:Physical Exertion / Q000502:physiology*; D012420:Running / Q000502:physiology*; D013715:Tennis / Q000502:physiology*; D055815:Young Adult
keywords: GPS; energy expenditure; inertial movement analysis; microsensor technology; speed