Use of target heart rate or target swimming time to control exercise intensity during interval swimming training

The physiological responses of 12 competitive swimmers to a standard training workout of four sets of six 100 m freestyle repetitions per set were measured in two trials. By random assignment the swimmers attempted to keep the workout constant in each trial by maintaining either a target heart rate (HR) or a target time for the 100 m efforts. The target HR or time was determined from these values measured at the anaerobic threshold (AT) during an initial determination of this exercise level. The HR after each repetition, 50 m split time, and blood lactate concentration after each set were measured throughout each workout for each swimmer. When target HR was used as the exercise criterion, the group mean (± SD) HR for the first set of six 100 m repetitions (173 ±11 beats/min) was significantly lower (p ≤ 0.05) than the group mean AT target HR (182 ± 11 beats/min), but the group mean HR for sets two, three, and four was not significantly different from the target value. Group mean lactate concentration afte...