| Study | Season(s) | Sport | Level (age) | Players | Impacts | Concussions |
| Duma et al. [39, 40] | 2003 | American football | Collegiate | 38 | 3312 | 1 |
| Brolinson et al. [41] | 2003-2004 | American football | Collegiate | 52 | 11,604 | 3 |
| Gwin et al. [42] | 2005 | Ice hockey | Collegiate | 4 | 1875 | 0 |
| Greenwald et al. [43] | 2003–2006 | American football | Collegiate | 423 | 249,613 | 11 | 2005 | Ice hockey | Collegiate | 5 | 5463 | 0 |
| Funk et al. [44] | 2003–2005 | American football | Collegiate | 56 | 22,704 | 3 |
| Funk et al. [45] | 2003–2007 | American football | Collegiate | 64 | 27,319 | 4 |
| Guskiewicz et al. [46] | 2004–2006 | American football | Collegiate | 88 | 104,714 | 13 |
| Mihalik et al. [47] | 2005-2006 | American football | Collegiate | 72 | 57,024 | 0 |
| Schnebel et al. [48] | 2005 | American football | High school | 16 | 8326 | 3 | Collegiate | 40 | 54,154 | 3 |
| Greenwald et al. [49] | 2004–2006 | American football | High school | 190 | 99,862 | 6 | Collegiate | 259 | 190,054 | 11 |
| Mihalik et al. [50] | 2006/2007 | Ice hockey | Youth (13 years) | 14 | 4543 | 0 |
| Beckwith et al. [51] | 2005–2008 | American football | High school, collegiate | 52 | 71,390 | 55 |
| Brainard et al. [52] | 2008-2009 | Ice hockey | Collegiate | 10 | Not reported | 0 |
| Broglio et al. [53] | 2007 | American football | High school | 35 | 19,224 | 0 |
| Cubos et al. [54] | 2006/2007 | Ice hockey | Youth (13-14 years) | 13 | 1137 | 0 |
| Duma and Rowson [55] | 2003–2008 | American football | Collegiate | 64 | 71,300 | 6 |
| Gwin et al. [56] | 2005-2006 | Ice hockey | Collegiate | 12 | 4393 | 0 |
| Rowson et al. [57] | 2007 | American football | Collegiate | 10 | 1712 | 0 |
| Broglio et al. [58] | 2005–2008 | American football | High school | 78 | 54,247 | 13 |
| Crisco et al. [59] | 2007 | American football | Collegiate | 188 | Not reported | 0 |
| Broglio et al. [58] | 2007–2010 | American football | High school | 95 | 101,994 | 20 |
| Mihalik et al. [60] | Not reported | Ice hockey | Youth (14 years) | 16 | Not reported | 0 |
| Reed et al. [61] | 2006-2007 | Ice hockey | Youth (13-14 years) | 13 | 1821 | 0 |
| Kimpara et al. [62] | 2007-2008 | American football | Collegiate | 19 | 4709 | 0 |
| Beckwith et al. [63, 64] Beckwith et al. [65] | 2005–2010 | American football | High school, collegiate | 1208 | Not reported | 105 |
| Brainard et al. [66] | 2008/2009-2009/2010 | Ice hockey | Collegiate | 44 | 15,281 | 0 |
| Breedlove et al. [67] | 2009-2010 | American football | High school | 24 | Not reported | 4 |
| Daniel II et al. [68, 69] | Not reported | American football | Youth (7–8 years) | 7 | 748 | 0 |
| Duhaime et al. [70] | Not reported | American football, ice hockey | Collegiate | 450 | 486,594 | 48 |
| Funk et al. [71] | 2006–2010 | American football | Collegiate | 98 | 37,128 | 8 |
| Gysland et al. [72] | Not reported | American football | Collegiate | 46 | Not reported | 0 |
| Mihalik et al. [73] | Not reported | Ice hockey | Youth (13–16 years) | 52 | 12,253 | 0 |
| Ocwieja et al. [74] | 2010 | American football | Collegiate | 46 | 7992 | 0 |
| Rowson et al. [75] | 2007–2009 | American football | Collegiate | 335 | 300,977 | 57 |
| Rowson et al. [76] Urban et al. [77] | 2012 | American football | Youth (7–12 years), middle school, high school | 112 | 34,603 | 8 |
| Cobb et al. [78] | Not reported | American football | Youth (9–12 years) | 50 | 11,978 | 4 |
| Talavage et al. [79] | 2009 | American football | High school | 21 | 15,264 | 4 |
| Urban et al. [77, 80] Stitzel et al. [81] | Not reported | American football | High school | 40 | 16,502 | 5 |
| Daniel II et al. [82] | 2012 | American football | Youth (12–14 years) | 17 | 4678 | 1 |
| Stitzel et al. [81] | Not reported | American football | Youth (9–12 years) | 36 | 9772 | 0 |
| Wilcox et al. [83] | 2009/2010–2011/2012 | Ice hockey | Collegiate | 41 | 19,880 | 0 |
| Young et al. [84] | 2011-2012 | American football | Youth (7-8 years) | 19 | 3059 | 0 |
| Cummiskey [85] | 2013 | American football | High school | 12 | 224 | 0 |
| Munce et al. [86] | Not reported | American football | Youth (11–13 years) | 22 | 6183 | 1 |
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