Bushman et al. 1997, Effect of 4 wk of deep water run training on running performance

Competitive distance runners who replaced all land running with four weeks of deep-water running maintained 5 km race time, running economy, lactate-threshold velocity and VO₂max, with no significant change in any measure. Med Sci Sports Exerc 29(5):694-9. Small cohort and a four-week window; demonstrates short-term maintenance of running-specific performance, not a training gain in healthy runners. Moderate.