Table 2.

Comparison of player characteristics currently specialized in basketball by age of basketball specialization (percentages column-wise)

		Age <11 y		Age 11-13 y		Age 14+ y
Variable	Group	n	%	n	%	n	%	P a
Sex	Male	126	75	91	83	51	89	0.042 b
	Female	42	25	19	17	6	11
	Total	168		110		57
Age at survey, y	Mean (SD)	15.8 (1.5)		16.0 (1.4)		17.2 (1.1)		<0.001 c
	13	19	11	5	5	0	0	0.002 d
	14	52	31	35	32	11	19
	15	17	10	6	5	5	9
	16	32	19	35	32	17	30
	17	36	21	21	19	12	21
	18	12	7	8	7	12	21
	Total	168		110		57
What is your current national recruiting ranking among all players in your class?	1-50	50	30	35	32	18	32	0.098
	50-100	7	4	7	6	5	9
	101-250	9	5	0	0	1	2
	Outside the top 250	13	8	8	7	9	16
	Unknown	89	53	60	55	24	42
	Total	168		110		57
How old were you when you first started playing on a select or elite club basketball team?	≤10	101	60	34	31	21	37	<0.001 e
	11	25	15	18	16	7	12
	12	14	8	22	20	5	9
	13	12	7	16	15	4	7
	14	7	4	7	6	11	19
	15	1	1	6	5	3	5
	16	2	1	1	1	1	2
	17	1	1	0	0	0	0
	Never played on select team	1	1	2	2	2	4
	Unknown/missing	4	2	4	4	3	5
	Total	168		110		57
Total games played approximately (all seasons)	≤25	13	8	13	13	5	9	0.798
	26-50	64	40	39	38	18	33
	51-75	62	39	37	36	25	46
	76-100+	21	13	15	14	6	11
	Total	160		104		54
Across a typical year, I . . . (choose one answer)	Never have time off from organized basketball; I play organized basketball all year	57	38	30	29	9	17	0.006 f
	Have a few weeks off (but less than a full month) from organized basketball without any games or practice	67	44	42	41	28	52
	Have about 1 full month off from organized basketball without any games or practices	21	14	24	23	8	15
	Have 2 or more months off from organized basketball without any games or practices under a coach’s supervision	7	5	7	7	9	17
	Total	152		103		54
During the high school basketball season (from November through March), when my coach gives the team a day off, I typically: (choose one)	Take off the entire day to rest (no physical activity)	37	25	23	24	10	20	0.347
	Go to the gym to shoot around or play pick-up	55	37	35	36	23	45
	Put myself through a skill development workout	22	15	19	20	13	25
	Put myself through a strength and agility, or cardiovascular workout, but I do not do anything on the basketball court	22	15	15	16	5	10
	Not applicable; my coach does not give us any days off	11	7	4	4	0	0
	Total	147		96		51
Have you undergone a surgery for a basketball-related injury?	No	129	83	87	82	43	84	0.941
	Yes	27	17	19	18	8	16
	Total	156		106		51
Have you ever seen a doctor for a basketball related injury?	No	14	40	4	19	1	20	0.223
	Yes	21	60	17	81	4	80
	Total	35		21		5
Have you had to sit out from basketball for 1 month or longer due to a basketball-related injury?	No	44	54	25	53	6	35	0.369
	Yes	38	46	22	47	11	65
	Total	82		47		17
During the school year, how many hours of sleep do you get in a typical night?	≤5	5	7	2	5	0	0	0.974
	6	7	10	4	10	1	6
	7	26	36	16	38	7	44
	8	30	41	17	40	6	38
	9	5	7	3	7	2	13
	Total	73		42		16
During the summer (when school is not in session), how many hours of sleep do you get in a typical night?	≤5	10	14	0	0	0	0	0.169
	6	13	18	9	21	2	13
	7	7	10	4	10	2	13
	8	20	27	9	21	2	13
	9	12	16	11	26	6	38
	≥10	11	15	9	21	4	25
	Total	73		42		16
In the past year, have you felt physically exhausted from basketball?	No	36	51	15	36	7	44	0.268
	Yes	34	49	27	64	9	56
	Total	70		42		16
In the past year, have you ever felt mentally exhausted from basketball?	No	47	65	19	45	6	40	0.049 g
	Yes	25	35	23	55	9	60
	Total	72		42		15
Survey date	January 2018	42	25	26	24	6	11	0.183
	June 2018	52	31	25	23	17	30
	August 2018	45	27	33	30	19	33
	August 2019	29	17	26	24	15	26
	Total	168		110		57

^aBoldfaced P values indicate statistical significance.

^bPost hoc tests indicate a significantly higher percentage of females in the specialized <11 years age group versus 14+ years (P = 0.021).

^cPost hoc tests indicate the mean age of the specialized 14+ years age group was significantly higher than the age 11 to 13 years (P = 0.011) and age <11 years (P < 0.001) specialization groups.

^dPost hoc tests indicate that the percentage of 13-year-old players in the <11 years group was significantly higher than 11 to 13 years (P = 0.050) and 14+ years (P = 0.006) specialization groups.

^ePost hoc tests indicate that the percentage of players who began playing on a select or club basketball team before the age of 10 years was higher in players who began their specialization before age 11 years compared with those who specialized between age 11-13 years (P < 0.001) and those who specialized at age 14 years and older (P = 0.004).

^fPost hoc tests indicate the percentage of players who specialized at age <11 years reported a significantly higher percentage of never having time off from organized basketball compared with players who specialized at age 14+ years (P = 0.005).

^gPost hoc tests indicate that players who specialized in basketball before age 11 years had significantly lower percentage of feeling mentally exhausted from basketball in the past year compared with players who specialized between age 11 to 13 years (P = 0.037) and age 14 years and older (P = 0.050).