Most leagues base their rest rules on innings pitched but as we all know an inning can be anything from 3 pitches to several dozen. The better measure is pitch count - and every outing, no matter how short, requires some recovery time.

Special Notice: In August 2006, Little League became the first youth league to announce a switch from innings pitched to pitch count. Each of the charts below has been updated with columns to reflect the LL rules as of 2007 and again as of 2010. We are glad to see any league impose limits. But we caution that no league follows the USA Baseball numbers that were based on ASMI research and in fact are often quoted by the ASMI itself.

For the record, no 11 y.o. we coach would ever be allowed to pitch 85 pitches; we are reluctant to let a 15 y.o. pitch 95. We are also concerned that no mention was made of ambient temperature ...pitching when it's 65F (18C) is different than at 85F (30C) .

Also not factored in (by any league) is the degree of warm-up required so that no pitcher takes the mound from a cold start. Complicating this further, there are newer insights that suggest pitch count per game is inadequate as a way to assess overuse injury risk. For the Ron Wolforth take on this, start here.

Here's what USA Baseball has determined is safest
based on ASMI research and cited by the ASMI,
compared to what Little League makes mandatory...

Suggested Pitch Counts (now mandatory for LL)
Age	USAB max. pitches/game	USAB max. pitches/week	LL 2007 pitches/day	LL 2010 pitches/day
7-8				50
9-10	50	75	75	75
11-12	75	100	85	85
13-14	75	125	95	95
15-16	91	*	95	95
17-18	106	*	105	105

Suggested Recovery Days
Age	1 day rest after	2 days after	3 days after	4 days after
8-10	21 pitches	34	43	51
11-12	27	35	55	58
13-14	30	36	56	70
15-16	25	38	62	77
17-18	27	45	62	89

Once you reach a certain number of pitches, you need this much rest/recovery time. These are derived from ASMI research, but are not the ASMI numbers (see below)

ASMI/LL Recovery Days (2010)
Age	No rest req'd	1 day rest after	2 days after	3 days after	4 days after
7-14	< 20	21-35	36-50	51-65	> 66
15-18	< 30	31-45	46-60	61-75	> 76

If you are surprised that LL thinks a 7 year old and 14 year old recover equally well, it was the ASMI in 2009 who suggested the first row apply to all ages (7-18). Many leagues split the ages into even more ranges than LL and are even more "inventive" in setting their maximums.

In our own experience, the actual recovery is very pitcher specific which depends more on training protocols and is not always obvious from size or build.