Table 1.

Study population characteristics (percentages column-wise)

Variable	Group	Total (N = 772)		Male (N = 627)		Female (N = 145)		P a
		n	%	n	%	n	%
Age, y, at survey	Mean (SD)	16.3 (1.5)		16.6 (1.3)		14.9 (1.3)		<0.001 b
	13	49	6	19	3	30	21
	14	172	22	95	15	77	53
	15	70	9	59	9	11	8
	16	159	21	149	24	10	7
	17	214	28	203	32	11	8
	18	108	14	102	16	6	4
	Total	772		627		145
What is your current national recruiting ranking among all players in your class?	1-50	170	22	154	25	16	11	<0.001 c
	50-100	47	6	44	7	3	2
	101-250	38	5	37	6	1	1
	Outside the top 250	102	13	101	16	1	1
	Not available or player did not know	410	53	288	46	122	85
	Total	767		624		143
How old were you when you first started playing on a select or elite club basketball team?	≤10	328	43	256	41	72	50	0.002 d
	11	106	14	82	13	24	17
	12	84	11	67	11	17	12
	13	70	9	50	8	20	14
	14	69	9	62	10	7	5
	15	30	4	29	5	1	1
	16	9	1	9	1	0	0
	17	4	1	4	1	0	0
	Never played on select team	40	5	38	6	2	1
	Unknown/missing	29	4	27	4	2	1
	Total	769		624		145
Is basketball currently the only organized sport that you play? e	Yes	349	73	280	77	69	62	0.002
	Total	476		365		111
At what age did you begin to specialize in basketball only?	5-10	168	48	126	45	42	61	0.235
	11	34	10	26	9	8	12
	12	39	11	32	11	7	10
	13	37	11	33	12	4	6
	14	28	8	23	8	5	7
	15	20	6	19	7	1	1
	16	8	2	8	3	0	0
	17	1	0	1	0	0	0
	I don’t know	14	4	12	4	2	3
	Total	349		280		69
Total number of games played in the last 12 months	≤25	101	14	76	13	25	18
	26-50	273	37	226	38	47	33
	51-75	263	36	210	36	53	37
	76-100+	93	13	76	13	17	12
	Total	730		588		142
Reported time off in the past 12 months	No time off reported	199	28	164	29	35	25	0.163
	<1 month	295	42	218	39	77	55
	1-2 months	126	18	109	19	17	12
	2+ months	85	12	75	13	10	7
	Total	705		566		139
During the basketball season (from November through March), when my coach gives the team a day off, I typically:	Take off the entire day to rest	198	29	150	27	48	35	0.344
	Shoot around or play pick-up	242	35	194	35	48	35
	Skill development workout	114	17	94	17	20	15
	Strength and agility, or cardio	102	15	87	16	15	11
	Not applicable, I have no off days	32	5	26	5	6	4
	Total	688		551		137
Have you undergone a surgery for a basketball-related injury?	Yes	123	17	109	18	14	10	0.015
	No	622	83	492	82	130	90
	Total	745		601		144
Have you had to sit-out from basketball for one month or longer due to a basketball-related injury	Yes	116	49	78	58	38	37	0.001
	No	122	51	57	42	65	63
	Total	238		135		103
During the school year, how many hours of sleep do you get in a typical night? f	≤5	12	6	8	7	4	4	0.410
	6	27	13	10	9	17	17
	7	74	35	39	35	35	35
	8	78	37	42	38	36	36
	9	18	9	11	10	7	7
	≥10	1	0	1	1	0	0
	Total	210		111		99
During the summer (when school is not in session), how many hours of sleep do you get in a typical night?	≤5	20	10	9	8	11	11	0.803
	6	34	16	19	17	15	15
	7	25	12	15	14	10	10
	8	49	23	26	24	23	23
	9	44	21	20	18	24	24
	≥10	37	18	21	19	16	16
	Total	209		110		99
In the past year, have you felt physically exhausted from basketball?	Yes	112	55	47	44	65	66	0.001
	No	93	45	60	56	33	34
	Total	205		107		98
In the past year, have you ever felt mentally exhausted from basketball?	Yes	94	45	51	47	43	43	0.585
	No	113	55	57	53	56	57
	Total	207		108		99

^aBoldfaced P values indicate statistical significance.

^bP value indicates mean age of male players was higher than female players.

^cAnalysis for P-value calculation indicates association between rank and player gender.

^dP value indicates statistical association between age at which player first started playing on select team and player gender. Post hoc analysis reports that female players had higher rate of playing on select team at age 10 years or younger compared with males (P = 0.050).

^eDesign error in the online survey resulted in a subset of sports specialization questions being skipped in by 293 participants at the first event, resulting in the lower n available for the specialization analyses.

^fQuestions related to sleep and perception of physical and mental exhaustion from basketball were added after the first event and were therefore not provided to all participants.