REF-940 · Peeling et al., 2005 · British Journal of Sports Medicine, Vol. · Paper · PubMed

Effect of swimming intensity on subsequent cycling and overall triathlon performance

Blimited evidenceMeasured on highly trained athletesWritten before October 2026, being re-checked

The aim was to see how swim intensity changes the cycling and overall triathlon performance that follow.

Nine highly trained male triathletes did five lab sessions — one graded exercise test, one STT (swim time trial) and three sprint-distance triathlons, swimming at 80-85% (S80), 90-95% (S90) or 98-102% (S100) of STT velocity and then cycling and running at what felt like maximal intensity.

Cycling was faster after the S80 and S90 swims than after S100, and the S80 triathlon was faster overall than the S100 one. The S100 swim brought a higher stroke rate and a higher plasma lactate concentration. The authors conclude that swimming below time-trial effort significantly improves the cycling that follows and overall triathlon performance.

Participants

n=9 highly trained, male triathletes.

Protocol

Five separate laboratory sessions: one graded exercise test, a swim time trial (STT), three sprint distance triathlons (TRI).
Swim velocity in the three TRI: 80-85% (S80), 90-95% (S90), 98-102% (S100) of STT velocity; cycling and running at a perceived maximal intensity.
Stroke mechanics during the swim; plasma lactate and ratings of perceived exertion after the swim and during cycling and running; oxygen consumption during the cycle.

Key Results

Cycle time: S80 and S90 faster than S100 (p<0.05).
Overall triathlon time: S80 faster than S100 (p<0.05).
S100 swim: greater stroke rate than S80 and S90 (p<0.05); greater plasma lactate than S80 (p<0.01).
The abstract gives no times or magnitudes.

Practical Application

In nine highly trained male triathletes racing laboratory sprint-distance triathlons, swimming at 80-85% of time-trial velocity gave a faster bike split and a faster overall time than swimming at 98-102%; the 90-95% swim also gave a faster bike than the all-out swim. To "should I go all-out in the triathlon swim?": no — a swim held below time-trial effort was repaid on the bike and in the total time.
The all-out swim came with a higher stroke rate and higher lactate out of the water: the cost is carried onto the bike.
Inference, not tested here: in a draft-legal or pack-start race, making the front group can be worth a harder swim; this laboratory design had no drafting and no positioning, so it measures only the physiological cost.
Inference, not tested here: swim drafting REF-939 is the way to hold a group's speed at a lower effort.
Not from this paper; the base's own practice: the triathlon frameworks SYNTH-52 and the swim framework SYNTH-74 set race swim pace relative to CSS rather than "as hard as possible".

Limitations

n=9 highly trained men; sprint distance only; laboratory conditions.
No times or effect sizes in the abstract — direction and significance only.
No significant overall-time difference is reported for S90 vs S100.
No drafting or positioning, so the tactical value of a fast swim is not captured.
Written from the abstract and record metadata only (full text not read).
How this entry was checked and changed
Why this level

within-subject crossover, n=9