TABLE 3.

Constant effort task performance.

Effort level	Variable	mTBI	Orthopedic control
	n	21	23
25%	Actual pressure	29.7 ± 3.1	30.1 ± 3.7
	TC	13 ± 6	14 ± 7
	RMSE	0.79 ± 0.7	0.56 ± 0.24
	n	29	33
50%	Actual pressure	45.1 ± 5.9	51.2 ± 4.2
	TC	13 ± 6	12.9 ± 6
	RMSE	1.8 ± 1	1.4 ± 1
	n	18	31
75%	Actual pressure	55.3 ± 10.6	64.3 ± 5.4
	TC	13 ± 6	13 ± 6
	RMSE	2.9 ± 1.4	2.6 ± 1

There were no significant group differences in average performance across the entire task or for each effort level. All the subjects increased pressure on the bulb (measured within the first 10 s of each trial) as instructed per effort level. Both groups tended to undershoot the prescribed effort level, although the mTBI group had a larger undershoot and more variance at the higher effort levels. RMSE, root mean square error of the time constant.