Comparative Effects of Sand- and Grass-Based Repeated-Sprint Training on Aerobic and Anaerobic Performance in Soccer Players

Table 2. Effects of six weeks repeated sprint training on jump and repeated sprint-related variables of college soccer players (mean ± SD).

Variables	Groups	Pre-intervention	Post-intervention	Pre-Post (%)	Interaction effect	Hedges’ g (95%CI)
SJ (cm)	SAND	40.8 ± 2.41	43.7 ± 2.19 ^{a,b c}	6.9 ^b,c	F = 50.7; p < 0.01	2.02 (1.12, 2.91) Very Large↑
	GRASS	40.4 ± 2.46	42.3 ± 2.28 ^a,b	4.7 ^b		1.36 (0.56, 2.16) Large↑
	CON	40.9 ± 2.74	40.6 ± 2.55	-0.8		-0.22 (-0.94, 0.50) Small↓
CMJ (cm)	SAND	44.1 ± 2.46	47.7 ± 2.42 ^a,b	8.2 ^b	F = 44.1; p < 0.01	2.03 (1.14, 2.93) Very Large↑
	GRASS	44.1 ± 2.48	47.0 ± 2.43 ^a,b	6.5 ^b		1.61 (0.78, 2.44) Large↑
	CON	44.4 ± 2.47	43.9 ± 2.63	-1.2		-0.30 (-1.03, 0.42) Small↓
Best sprint time (s)	SAND	5.0 ± 0.07	4.9 ± 0.07 ^a,b	-2.1 ^b	F = 40.4; p < 0.01	-1.58 (-2.41, -0.75) Large↓
	GRASS	5.0 ± 0.09	4.9 ± 0.08 ^a,b	-2.0 ^b		-1.46 (-2.28, -0.65) Large↓
	CON	5.0 ± 0.06	5.0 ± 0.05	-0.03		-0.02 (-0.74, 0.70) Trivial↓
Peak power (w)	SAND	717.2 ± 23.93	762.7 ± 20.94 ^a,b	6.4 ^b	F = 35.3; p < 0.01	1.94 (1.06, 2.82) Large↑
	GRASS	718.4 ± 23.87	758.0 ± 21.19 ^a,b	5.5 ^b		1.67 (0.83, 2.52) Large↑
	CON	715.8 ± 23.94	713.3 ± 24.29	-0.4		-0.11 (-0.83, 0.61) Trivial↓
Minimum power (w)	SAND	445.3 ± 19.70	533.3 ± 20.63 ^a,b,c	19.8 ^b,c	F = 136.9; p < 0.01	1.29 (0.50, 2.09) Large↑
	GRASS	443.6 ± 20.00	511.8 ± 21.29 ^{a b}	15.4 ^b		1.00 (0.23, 1.77) Moderate↑
	CON	454.5 ± 19.04	446.4 ± 21.97	-1.8		-0.12 (-0.84, 0.60) Trivial↓
Mean power (w)	SAND	571.2 ± 27.01	640.1 ± 21.12 ^a,b,c	12.1^b	F = 58.3; p < 0.01	1.96 (1.07, 2.84) Large↑
	GRASS	563.3 ± 27.02	616.5 ± 25.28 ^a,b	9.4 ^b		1.51 (0.69, 2.33) Large↑
	CON	571.2 ± 25.75	562.4 ± 25.68	-1.5		-0.25 (-0.97, 0.47) Small↓
Fatigue index	SAND	8.3 ± 0.32	7.3 ± 0.37 ^a,b,c	-12.1 ^b,c	F = 29.9; p < 0.01	-1.87 (-2.74, -1.00) Large↓
	GRASS	8.4 ± 0.42	7.8 ± 0.33 ^a,b	-7.1 ^b		-1.12 (-1.90, -0.35) Moderate↓
	CON	8.0 ± 0.44	8.2 ± 0.45	2.5		0.37 (-0.35, 1.10) Small↑

^a Significantly different from pre-intervention (p < 0.05);^b Significantly different from CON (p < 0.05);^c Significantly different from GRASS (p < 0.05).