Thirty-four college-age fitness swimmers, 19 males and 15 females, were maximally tested during treadmill running (TR) and tethered swimming (TS). A discontinuous, graded test protocol was used for both TR and TS with 2-min stages and 1-min rest periods. Peak HRs were obtained via a UNIQ CIC monitor during the last 120 s of each stage. Blood lactate was measured at 3 min post exercise using a YSI Model 27 Analyzer. TS peak HR was significantly lower (p less than 0.05) than both the age-predicted HRmax (220-age) and TR peak HR by 13 and 11 bt.min-1, respectively. Blood lactate for TS (8.0 mmol.l-1) and TR (8.1 mmol.l-1) were similar. Mean target heart rate range (THRR) calculated from TS peak HR (144-176 bt.min-1) was significantly lower than THRR calculated from age-predicted max HR (151-187 bt.min-1) and TR peak HR (151-186 bt.min-1). For young adult fitness swimmers, we suggest reducing the HRmax obtained from treadmill exercise or predicted from age by 12 bt.min-1. This correction appears to be a reasonable estimate of swimming HRmax that can be used for calculating exercise intensity.