Supplementary Table 8.

ACSM Fitness Classifications for Plank by Age Group and Sex.

Sex	Category	Seconds	20–29 (n)	30–39 (n)	40–49 (n)	50–59 (n)	60–69 (n)
Male	Very Poor	0 – 79	0	15	5	0	0
	Poor	80 – 97	0	17	5	0	0
	Fair	98 – 122	0	36	8	0	0
	Good	123 – 157	0	36	6	0	1
	Excellent	158 – 201	0	29	9	0	0
	Superior	> 201	0	37	9	3	0
Female	Very Poor	0 – 35	0	1	1	0	1
	Poor	36 – 63	0	10	2	0	0
	Fair	64 – 84	0	6	3	0	1
	Good	85 – 108	0	10	1	1	0
	Excellent	109 – 142	1	15	8	0	0
	Superior	> 143	0	17	5	0	0

Notes: ACSM = American College of Sports Medicine. Column headers (e.g., 20–29 (n), 30–39 (n)) indicate the number of participants within each age group.