Effects of Two In-Season Short High-Intensity Interval Training Formats on Aerobic and Neuromuscular Performance in Young Soccer Players

Table 1. Typical weekly training schedule during the intervention (upper part) and the control periods (lower part).

Typical training schedule during the intervention period
Day 1 (90 min)	Day 2 (90 min)	Day 3 (90 min)	Day 4 (90 min)	Day 5 (50 min)	Match day	Day off
HIIT/ BallTrain	Ball_Train	HIIT/ BallTrain	Ball_Train	Ball_Train	Rest
Warm-up routine -HIIT (10s/10s or 15s/15s), 2 x 6 min/3 min rest. -Small sided games, 2 x 6 min/3 min rest. -Tactical games, 3 x 8 min/3 min rest. Cool-down routine	-Passing games, 2 x 8 min/3 min rest. -Small-sided games, 4 x 4 min/3 min rest. -Tactical games, 2 x 8 min/3 min rest. Cool-down routine	-HIIT (10s/10s or 15s/15s), 2 x 6 min/3 min rest. -Small sided games, 2 x 6 min/3 min rest. -Tactical games, 3 x 8 min/3 min rest. Cool-down routine	-Agility 8 min/3 min rest. -Middle-sided games, 2 x 6 min/3 min rest. -Tactical games 3 x 8 min/3 min rest. Cool-down routine	-Agility 8 min/3 min rest. -Passing games, 2 x 6 min/3 min rest. -Tactical games, 2 x 6 min/3 min rest. Cool-down routine	Rest
Typical training schedule during the control period
Day 1 (90 min)	Day 2 (90 min)	Day 3 (90 min)	Day 4 (90 min)	Day 5 (50 min)	Match day	Day off
Ball_Train	Ball_Train	Ball_Train	Ball_Train	Ball_Train	Rest
-Passing games, 2 x 6 min/3 min rest. -Small-sided games, 2 x 6 min/3 min rest. -Tactical games, 3 x 8 min/3 min rest. Cool-down routine	-Passing games, 2 x 8 min/3 min rest. -Small-sided games, 4 x 4 min/3 min rest. -Tactical games, 2 x 8 min/3 min rest. Cool-down routine	-Passing games, 2 x 6 min/3 min rest. -Small-sided games, 2 x 6 min/3 min rest. -Tactical games, 3 x 8 min/3 min rest. Cool-down routine	-Agility 8 min/3 min rest. -Middle-sided games, 2 x 6 min/3 min rest. -Tactical games 3 x 8 min/3 min rest. Cool-down routine	-Agility 8 min/3 min rest. -Passing games, 2 x 6 min/3 min rest. -Tactical games, 2 x 6 min/3 min rest. Cool-down routine	Rest

Agility: ladder drills, hurdles, bosu and ball; Ball_Train: training with ball; HIIT: high intensity interval training; Sessions: Day of week (duration of session).