REF-1441 · DiCarlo et al., 1991 · International Journal of Sports Medicine · Paper · PubMed

Is my heart rate lower when I swim than when I run?

Yes at the top: in 34 fitness swimmers, tethered-swim peak heart rate was 11 bpm below the treadmill peak; the authors suggest subtracting 12 bpm. Group mean, 1991, abstract.

Main caveat: Abstract only; no absolute values, SDs or individual data.
moderate evidenceMeasured on recreational people

DiCarlo and colleagues (Georgia Institute of Technology) tested 34 college-age fitness swimmers, 19 men and 15 women, to maximum in treadmill running and in tethered swimming, each with a discontinuous graded protocol of 2-min stages and 1-min rests. Peak heart rate was taken with a chest monitor over the last 120 s of each stage and blood lactate 3 min after exercise.

Tethered-swim peak heart rate was significantly lower than both the age-predicted maximum (220 − age) and the treadmill peak, by 13 and 11 beats/min. Post-exercise lactate was similar (8.0 vs 8.1 mmol/L), suggesting comparable maximal efforts.

The mean target heart-rate range calculated from the swim peak (144-176 beats/min) was significantly lower than the ranges from the age formula (151-187) and from the treadmill peak (151-186). The authors suggest that young adult fitness swimmers reduce a treadmill-measured or age-predicted maximum by 12 beats/min to estimate their swimming maximum.

Our reading: the base had no entry on swimming heart rate against land; this gives a same-person number — roughly 11-13 bpm lower at the top in the pool — for fitness swimmers.

It is a group mean from 1991 with tethered swimming; elite swimmers in a later study outside the base showed about 7 bpm, so the offset varies with the swimmer, and SYNTH-74's product rule not to prescribe swim sets by heart rate stands.

Protocol

Participants: n = 34 college-age fitness swimmers (19 men, 15 women).
Tests: treadmill running and tethered swimming to maximum; discontinuous graded protocol, 2-min stages, 1-min rest periods.
Heart rate: chest monitor (UNIQ CIC), peak over the last 120 s of each stage.
Lactate: 3 min after exercise (YSI Model 27 analyser).
Target ranges: computed from each maximum (method not given in the abstract).
Funding and interests: none listed in the PubMed or Crossref record; no conflict statement in the abstract record.

Key Results

MeasureTethered swimmingTreadmill runningAge-predicted (220 − age)
Peak heart rate vs swimmingreference11 bpm higher13 bpm higher
Post-exercise lactate (mmol/L)8.08.1—
Mean target heart-rate range (bpm)144-176151-186151-187
Authors' suggested correction: subtract 12 bpm from a treadmill or age-predicted maximum to estimate swimming maximum in young adult fitness swimmers.
Not in the abstract: absolute peak heart rates, SDs, individual differences, sex differences.

Mechanisms

Measured: a lower peak heart rate in tethered swimming than in running, at similar end-exercise lactate.
Authors' interpretation: the lower swimming maximum should be used when calculating swimming exercise intensity.
Inference: a horizontal posture, immersion (which raises stroke volume) and a smaller, mostly upper-body active muscle mass all lower the heart-rate ceiling in water; the same direction as deep-water running (REF-1433).

Practical Application

Is my heart rate lower when I swim than when I run? Yes at the top: in 34 fitness swimmers, tethered-swim peak heart rate was 11 bpm below the treadmill peak; the authors suggest subtracting 12 bpm. Group mean, 1991, abstract.
Do not carry run or bike zones into the pool: expect the swimming maximum roughly 7-11 bpm lower than running's (11 below the treadmill peak here, and 13 below 220 − age, in fitness swimmers; about 7 in elite swimmers outside the base). SYNTH-74's rule not to prescribe swim sets by heart rate and to anchor pace to CSS still holds; this closes its "swim heart rate versus land — no entries" gap.
A runner or cyclist swimming instead: steer by effort and pace in the pool (the base's practice); a lower heart-rate ceiling in the pool is expected, while submaximal swim heart rate was not measured here.
What it does not show: submaximal swim heart rates at a given effort, free swimming, trained swimmers, individual spread.

Limitations

Abstract only; no absolute values, SDs or individual data.
Tethered swimming, not free swimming; discontinuous protocol with rests.
College-age fitness swimmers; no trained, masters or triathlete sample.
Old study (1991) with heart-rate equipment of the time.
Funding and interests: not stated in the record.
How this entry was checked and changed
Why this level

(from the abstract) — a within-subject comparison of 34 (the rubric's B+ band for crossovers of 15 or more); tethered swimming in college-age fitness swimmers, 1991 equipment, no individual spread in the abstract