This article from T. Rowe Price provides some examples of prudent and not so prudent strategies for recovering from a severe market downturn in retirement. The study cited in this article once again illustrates how making wholesale portfolio changes during such a time can be the very worst idea, while keeping the focus on reducing portfolio withdrawal rates is optimal.

The only thing I would add is this: Because not everybody can significantly reduce their living expenses during a market downturn, although most can do so more than they think, this is yet another reason why it is so important not to enter retirement undersaved or without a comfortable level of emergency cash reserves. To do otherwise is a big gamble.