TABLE 2.

Descriptives of included studies.

Dataset	Country	Sport	Level	Female/male	Mean age ± SD (years)	Mean lifetime concussion, range	Scan interval ± SD (days)	Season interval ± SD (days)	Recreational interval ± SD (days)
1 a	CA	AF	University	0/23	20.09 ± 1.31	0.91, 0–4	131.39 ± 26.67	60.91 ± 3.59	28.35 ± 7.53
2 b	US	AF	University	0/36	19.67 ± 1.17	‐	96.86 ± 7.45	49.00 ± 0.00 c	6.56 ± 5.57
3 d	CA	RU	University	43/0	19.65 ± 1.33	0.60, 0–3	158.43 ± 26.44	44.16 ± 6.60	117.97 ± 39.78
4 e	CA	IH	University	13/16	21.14 ± 3.51	‐	188.97 ± 20.16	132.14 ± 11.14	30.97 ± 7.24
Total				56/75	20.06 ± 2.06	0.71, 0–4	142.81 ± 40.56	67.91 ± 35.46	49.21 ± 50.87

Note: CA = Canada, US = United States, AF = American football, RU = rugby, IH = ice hockey, SD = standard deviation, scan interval = days between baseline and post‐season scan, season interval = days between season start and season end, recreational interval = days between season end and follow‐up scan.

^a Champagne et al. (2019).

^b Hirad et al. (2019).

^c Equal interval for all participants.

^d Manning et al. (2020).

^e Weber et al. (2018).