Mojo, you can also try L-glutamine in the recovery shake, when I was training for my half marathon I used it and felt I recovered a little faster. You need to take the runs outside now, the wind resisitance and hills out in nature are the best.
I will add to drink lots more water if you decide to supplement with creatine for the reasons grunt stated, water retention, etc.
I think for most of us around that 40yr old mark and I will guess most of us are not competing in anything any more, that just eating right and doing what we can to stay fit is all we really need to do.
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