be committed to doing / to do sth

[NicoBas]

I am in need of some guidance with regard to the following:
We normally say "sb is committed to sth" (e.g. she is committed to her family) where sth may be a gerund (e.g. she is committed to looking after her family). All this makes perfect sense as a gerund functions as a noun.
However, I have come across, much less frequently, "be (jointly) committed to do sth" or "have a commitment to do sth". (i.e. + infinitive rather than to + gerund)
Any ideas? I believe I have found a distinction, but prefer not to mention it so as not to bias any responses!

[Glenski]

Although I have not heard the infinitive expression, Michael Swan's Practical English Usage states:

section 296.11
...we can generally use either an -ing form or an infinitive without much difference in meaning (after expressions such as committed to).

[NicoBas]

Thanks for your input, Glenski! It's nice to know that some grammar book at least makes reference to the distinction. Upon close examination of the few examples I've come across, my conclusion is as follows:
It would seem to me that...
a) "be committed to doing sth" refers to energy, effort and time binding one to an ongoing activity, one that is already in progress;
b) "be committed to do sth" or "have a commitment to do sth" refers to a binding promise (can a promise be anythng but binding?!) to do sth, to achieve sth not yet begun, only just outlined or proposed, to seek an outcome.

What do you think of this? I'm interested in any comments.

[Glenski]

As I have never heard (or recall hearing, anyway) of the use of the infinitive, I really can't make any judgment call on your idea. Sorry.

[figarotheteacher]

Dear Nicobas,

I agree with the distinction you make. The change from gerund to verb does, in my opinion, make that change of connotation.