This article and many others are part of the awesome-cto list. If you're not already aware of it, I'd recommend poking through and reading the ones that stand out to you. My manager started a "book club" with the managers that report to him and this has been serving as a source of interesting discussion each month.
I switched from develoment to management (of the same team) just under 5 years ago now. Early on, I made the mistake of trying to still participate in some of the work, but I quickly abandoned that when it was obvious I was just getting in the way. My methods for staying sharp have adapted over the years. I don't really think full pendulum swings are necessary to stay effective.