Effects of a 6-Week Strength Training of the Neck Flexors and Extensors on the Head Acceleration during Headers in Soccer

Table 1. Characteristics and composition of the sample size without dropouts. Values are reported as mean ± standard deviation.

IG1	IG2	CG
n = 11 6^th German division age 22.7 ± 3.7 years height 181.1 ± 5.2 cm weight 76.9 ± 7.5 kg age of club entry (soccer) 4.8 ± 0.9 years soccer time per week 4-7 h/week	n = 9 3^th German youth division age 17.1 ± 0.9 years height 179.7 ± 7.6 cm weight 74.4 ± 11.7 kg age of club entry (soccer) 4.6 ± 0.8 years soccer time per week 4-7 h/week	n = 13 6^th, 7^th German division age 21.5 ± 1.4 years height 182.5 ± 6.9 cm weight 77.5 ± 6.1 kg age of club entry (soccer) 4.5 ± 1.5 years soccer time per week 4-7 h/week

IG1 intervention group 1; IG2 intervention group 2; CG control group.