REF-1438 · Gehring et al., 1997 · Medicine and Science in Sports and Exercise · Paper · PubMed

If I run in the pool at my usual effort, is it the same training?

Not for recreational runners: 7 women trying to match their land effort in water ran at 27% lower VO2 with a vest; 7 competitive women matched it. Small, 1997, abstract.

Main caveat: Abstract only; no absolute values or SDs.
limited evidenceMeasured on recreational to highly trained athletes

Gehring, Keller and Brehm (Smith College) asked whether competitive and recreational runners would reproduce their land-training intensity when running in water with and without a flotation vest.

Seven female competitive runners and seven female noncompetitive runners were asked to replicate the intensity of their preferred 45-min land run during 20-min submaximal runs under three conditions: treadmill, water with a vest, and water without a vest. The competitive runners reached a similar submaximal VO2 in all three conditions.

The recreational runners had significantly lower VO2 (27%), heart rate (23%), ventilation (26%) and %VO2max (27%) with the vest than on the treadmill; without the vest their VO2 and %VO2max were 13% lower and their RPE higher than on the treadmill, while VO2 (16%), heart rate (15%), ventilation (24%), %VO2max (15%) and RPE were higher than with the vest.

The authors conclude that competitive runners can reach land-like training intensities in water with or without a vest, but that recreational runners fail to, intensity being lower without a vest and lowest with one, despite efforts to maintain a similar level of exertion.

Our reading: "run in the pool as hard as you would on land" works for competitive runners and underdoses recreational ones by about a quarter with a vest — the base's typical user. It qualifies the operational line in REF-922, whose trained men ran prescribed %VO2max sessions.

It is a small, old study (1997); newer work in the base on deep-water running is the review REF-1437, which gives no dose.

Protocol

Participants: n = 14 women: 7 competitive runners, 7 noncompetitive runners.
Task: replicate preferred land-training intensity characteristic of a 45-min run, in 20-min submaximal runs.
Conditions: treadmill running; water running with a flotation vest; water running without a vest.
Measures: VO2, %VO2max, heart rate, ventilation, RPE.
Funding and interests: PubMed lists "Research Support, Non-U.S. Gov't"; no funder named and no conflict statement in the abstract record.

Key Results

Recreational runnersWith vest vs treadmillWithout vest vs treadmillWithout vest vs with vest
VO227% lower13% lower16% higher
Heart rate23% lowernot reported15% higher
Ventilation26% lowernot reported24% higher
%VO2max27% lower13% lower15% higher
RPE—higherhigher
Competitive runners: a similar submaximal VO2 on the treadmill, with the vest and without it.
Not in the abstract: absolute values, SDs, heart rates of the competitive group, water-running experience.

Mechanisms

Measured: recreational runners steering by perceived exertion produced far less metabolic and cardiac work in water, especially with a vest; competitive runners did not.
Authors' interpretation: recreational runners fail to replicate land training pace in water despite trying to keep the same exertion.
Inference: submaximal water running feels harder (REF-1433: RPE higher, and heart rate 8-11 bpm lower at the same oxygen uptake), so a runner matching feel undershoots; the vest removes the work of staying afloat, which lowers intensity further for those without a strong water-running technique. Competitive runners may have more practice or a better sense of their training intensity.

Practical Application

If I run in the pool at my usual effort, is it the same training? Not for recreational runners: 7 women trying to match their land effort in water ran at 27% lower VO2 with a vest; 7 competitive women matched it. Small, 1997, abstract.
Give water sessions structure: intervals, cadence and RPE anchored to a known land session rather than "run as you feel"; heart-rate targets lowered for the water (REF-1433). Not from this paper; the base's own practice.
The vest: with a vest the recreational runners worked least; without one, more (VO2 16% higher than with the vest) at a higher RPE. In these recreational runners the vest made underdosing easier; any benefit of a vest for form or safety is not tested here.
What it does not show: men, training effects over weeks, or whether practice closes the gap.

Limitations

Abstract only; no absolute values or SDs.
Seven per group, women only; one session per condition.
Water-running experience of each group not given in the abstract.
Old study (1997).
Funding: "Research Support, Non-U.S. Gov't" per PubMed; no conflict statement in the record.
How this entry was checked and changed
Why this level

(from the abstract) — a crossover of 14 (the rubric's B for crossovers under 15), 7 per group; women only, one session per condition, 1997