REF-937 · Zamparo et al., 2002 · Journal of Experimental Biology, Vol. · Paper · PubMed

How fins affect the economy and efficiency of human swimming

Blimited evidenceMeasured on a mixed groupWritten before October 2026, being re-checked

The study quantified the improvements in economy and efficiency of surface swimming brought about by fins, over a range of speeds that could be sustained aerobically. At comparable speeds the energy cost of swimming with fins was about 40 % lower than without; at the same metabolic power this allowed a speed about 0.2 m/s higher.

Fins only slightly decreased kick amplitude (by about 10 %) but caused a large reduction (about 40 %) in kick frequency, which lowered both the internal work rate and the power wasted in giving kinetic energy to the water. Froude efficiency was 0.70 with fins and 0.61 without, and mechanical efficiency was about 10 % larger with fins.

Participants

The abstract gives no sample size or level; MEDLINE indexing lists male participants, adolescent and adult.

Protocol

Surface swimming with and without fins over a range of aerobically sustainable speeds.
Energy cost (C) measured; kick amplitude and frequency and internal work rate from video analysis.
Froude efficiency computed from the speed of the bending waves moving along the body; power wasted to impart kinetic energy to the water derived from it.
Mechanical efficiency = total power (kinetic + internal + frictional) / (C x speed).

Key Results

Variable (with fins vs without, at comparable speeds)Result
Energy costabout 40 % lower with fins
Speed at the same metabolic powerhigher by about 0.2 ms(-1)
Kick amplitudelower by about 10 %
Kick frequencylower by about 40 %
Internal work ratelower by about 75 %
Power wasted to impart kinetic energy to the waterlower by about 40 %
Froude efficiency0.70 vs 0.61
Mechanical efficiency0.13+/-0.02 vs 0.11+/-0.02 (about 10 % larger with fins)
No difference in the power to overcome frictional forces between conditions at comparable speeds.

Practical Application

At comparable aerobic speeds, kicking with fins cost about 40 % less energy than kicking without, chiefly because kick frequency fell by about 40 % while amplitude fell only about 10 %; at the same metabolic power, speed was about 0.2 m/s higher. To "what do fins actually do?": they make each kick move more water more efficiently (Froude efficiency 0.70 vs 0.61), so the same speed is cheaper and the kick is slower.
A fins set at the usual pace is therefore an easier set metabolically; to keep the load, the speed has to go up.
Inference, not tested here: because fins lower kick frequency so much, fin kicking does not rehearse the kick rate of unassisted swimming — useful for body position and speed feel, not as a like-for-like substitute.
Inference, not tested here: this study did not examine whether training with fins improves swimming without them.
Not from this paper; the base's own practice: the gear rules in the swim framework SYNTH-74 (fins, paddles, pull buoy) are practice, not evidence.

Limitations

Sample size and swimmer level are not in the abstract.
Kicking with and without fins at aerobic speeds; not full-stroke front crawl and not sprinting.
An acute comparison: no training intervention, no performance test.
Fin type is not described in the abstract; results may differ with fin size and stiffness.
Written from the abstract and record metadata only (full text not read).
How this entry was checked and changed
Why this level

within-subject comparison; sample size not given in the abstract