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. 2021 Jul 23;18(15):7827. doi: 10.3390/ijerph18157827

Table 1.

Baseline data including anthropometrical, history of hamstring injury, and sprint acceleration mechanical output data at the start of the season, in addition to new hamstring injuries (i.e., primary outcome), for the total population and according to the three groups (i.e., Finland, Japan and France) or to the history of hamstring injury.

Total Per Groups Per History of Hamstring Injury
Japan France Finland No Previous
Hamstring Injury
History of Previous
Hamstring Injury
Number (n (%)) 284 (100) 110 (39) 56 (20) 118 (42) 224 (79) 60 (21)
Anthropometrical parameters (mean (SD))
Age (years) 21.4 (4.3) 20.0 (1.0) c** 18.2 (1.8) 24.3 (5.3) a,b*** 21.3 (4.1) 22.1 (5.2)
Height (cm) 176.7 (7.2) 172.7 (5.2) c*** 177.0 (6.7) 180.4 (7.0) a***,b** 176.7 (7.2) 177.0 (7.0)
Mass (kg) 71.3 (8.4) 66.9 (5.3) 68.1 (8.1) 77.0 (7.6) a,b*** 71.4 (8.5) 71.2 (8.3)
History of hamstring muscle injury
Number of players (%) 60 (21) 16 (15) 14 (25) 30 (25) 0 (0) 60 (100)
Sprint acceleration mechanical outputs (mean (SD))
Pmax (W·kg−1) 16.8 (1.6) 16.3 (1.4) c*** 17.3 (1.8) 16.9 (1.6) a** 16.7 (1.6) 17.1 (1.7)
FH0 (N·kg−1) 7.5 (0.6) 7.4 (0.6) 7.5 (0.6) 7.5 (0.6) 7.5 (0.6) 7.5 (0.6)
V0 (m·s−1) 9.0 (0.5) 8.8 (0.5) c*** 9.3 (0.6) 9.1 (0.4) a***,b** 9.0 (0.5) d* 9.1 (0.5)
F-v profile −0.83 (0.08) −0.84 (0.09)c* −0.81 (0.09) −0.83 (0.07) −0.84 (0.09) −0.82 (0.08)
New hamstring injury
Number of players with new hamstring injury (n (%)) 38 (13) 6 (6) 12 (21) 20 (17) 16 (7) 22 (37)
Number of new hamstring injury (n) 47 8 16 23 19 19
Incidence of new hamstring injury (per 1000 h of football (95% CI)) 0.4 (0.3 to 0.5) 0.1 (0.0 to 0.2) 0.8 (0.5 to 1.2) 0.6 (0.4 to 0.9) 0.2 (0.1 to 0.3) 0.8 (0.4 to 1.2)

a Finland differed from Japan and from France; b Finland differed from France; c Japan differed from France; d “No previous hamstring injury differed” from “History of previous hamstring injury”; * p < 0.05; ** p < 0.01; *** p < 0.001. 95% CI: 95% confidence interval. F-v profile corresponds to the slope of the F-v linear relationships. Among the 284 included players, a total of 241 injuries (95% leading to time loss in football) were reported during the season in 159 players (56%). The main injury diagnosis was ankle sprain (n = 52, 22%), followed by hamstring injury (n = 47; 20%); other injuries were lower limb non-muscle injuries except ankle sprain (26%), lower limb muscle injuries except hamstring injury (22%), and other injuries (10%). The incidence of hamstring injuries per 1000 h of football varied according the three groups (lower for Japan group) and between players with and without history of hamstring injury (higher in players with history of previous hamstring injury).