The phrase "lower investment returns" means that the money you have invested is not generating as much profit or earnings as it did before. Full definition
So how can you lower the odds of running out of money before you run out of time, especially given forecasts for low investment returns in the years ahead? (realdealretirement.com)
I'd also add that given forecasts for lower investment returns in the future, it's all the more crucial to hold down the portion of gross return that goes to expenses. (realdealretirement.com)
If you're already retired, the prospect of lower investment returns means spending more carefully, which for most people translates to a lower withdrawal rate when tapping your nest egg. (realdealretirement.com)