Kick, Pull Buoy, Paddles: Which Tools Help Triathletes and Which Become Crutches

Walk past any triathlon club lane and you'll see a bag of kit at the end: pull buoy, paddles, fins, maybe a snorkel. Some athletes use all of it in every session. Others never touch it. And the kick divides opinion more than almost anything else in triathlon swimming. One coach says "save your legs for the bike," another says "your kick is why your legs sink."

The research doesn't settle all of this, but it does narrow it. This article looks at what the kick actually contributes, what swim toys do to your stroke, the shoulder risk with paddles, and how to use each tool deliberately. Where the evidence runs out, which happens quickly for pull buoys, that's stated plainly.

What the kick actually does

A 1999 study by Deschodt and colleagues gives one of the clearest pictures. Eight male swimmers sprinted 25 m at maximum speed under four conditions: one arm, two arms, one arm plus legs, and normal swimming with arms and legs. Adding the legs increased maximal velocity by about 10%.

The interesting part is how. The researchers found that kicking modified the underwater path of the wrist "in an improved manner." They concluded that the legs mainly enhanced the arms' propulsion rather than producing large amounts of propulsion directly. In other words, a good kick helps your arms work better, likely by supporting body position and rotation and providing a stable base to pull against.

Caveats: eight male swimmers, maximal 25 m sprints, more than 25 years ago. The leg contribution at triathlon race pace, over 1,500 m in a wetsuit, is likely to be different and probably smaller in direct terms. But the principle that the kick supports the stroke as much as it propels is the useful part. It's also why "just don't kick" can backfire. A kick that's switched off can let the hips drop and make the arms work harder.

The cost of kicking

Kicking is expensive. In a 2006 study, Zamparo and colleagues measured the energy cost of kicking in ten swimmers, barefoot and with different fins. Barefoot kicking had the highest energy cost, about 10.6 kJ per metre per kilogram at a slow 0.8 m/s, and each kick covered only about 0.5 m. Fins reduced the cost substantially and increased the distance travelled per kick.

That supports the conventional triathlon wisdom: a big, hard kick costs a lot of energy for relatively little direct propulsion, and the legs then have to bike and run. It's the main reason triathletes are told to use a light kick in races.

The case for training the kick

There's a counterweight, and it's triathlon-specific. Ambrosini and colleagues (2024) assigned 15 triathletes to three groups for an 8-week swimming programme: a six-beat kick group, a four-beat kick group, and a control group. After training, the six-beat group:

• swam with a lower stroke frequency and a longer stroke length than the control group, and
• showed lower heart rate, oxygen uptake and energy expenditure during cycling immediately after swimming.

The authors concluded that high-kick training improved both swim technique and cycling efficiency in the swim-to-bike transition.

This is a small study, with roughly five athletes per group, and needs replication. But it challenges the simple "save your legs" rule. A plausible explanation, and this is TriForward's inference, is that a trained kick is a more efficient kick. It supports a longer stroke and better body position at lower cost, so the overall swim is cheaper, leaving more for the bike. A weak, untrained kick may be the worst option: it costs energy, still drags, and doesn't support the stroke.

Reconciling "save your legs" with "train your kick"

Putting these findings together gives a reasonable middle ground, which is reasoned rather than directly tested:

• In training: do some kick work, aiming for a compact, efficient kick from the hip that supports body position and timing.
• In races: use a light, rhythmic kick that keeps your body position and stroke timing intact, rather than a hard kick or none at all. Many triathletes kick a little harder near the end of the swim to bring blood flow back to the legs before standing up, though that practice isn't well studied.
• Don't switch the kick off entirely if it makes your hips drop. The arm cost of sinking legs may outweigh the leg energy saved.

A wetsuit changes this balance. A 2021 review by Quagliarotti and colleagues found wetsuits improve performance by up to 11%, largely through increased buoyancy and reduced drag, with benefits varying by ability. With a wetsuit holding your legs up, the kick has less work to do for body position, which is one reason many triathletes kick very lightly in wetsuit races. In non-wetsuit races, your kick may need to do more.

Pull buoys: useful, but under-researched

Pull buoys are probably the most-used piece of triathlon swim kit, and there's remarkably little direct research on them. We didn't find a controlled study of pull-buoy training in triathletes. What follows is reasoning from related evidence and coaching practice, labelled as such.

What a pull buoy does: it lifts the legs, removes or reduces the kick, and lets you focus on the arms. In that sense it mimics some of the buoyancy effect of a wetsuit.

Where it helps:

• Arm-focused technique work, when you want to concentrate on the catch or entry without worrying about the legs.
• Rehearsing wetsuit-like body position, so you feel what a high-hip position is like.
• Upper-body endurance sets, where the aim is to load the pulling muscles.

Where it can become a crutch:

• Hiding sinking legs. If you're only comfortable with a pull buoy, your body position without one needs work. Using the buoy every session can disguise that.
• Changing your rotation. A buoy between the thighs can restrict or alter hip rotation, so the stroke you rehearse may differ from your normal one.
• Making sets feel artificially easy, so you never build the swim fitness to hold form without support.

A simple test: swim 100 m with and without a pull buoy at the same effort. If the gap is large, perhaps more than 5-10 seconds for an age-grouper, body position is likely a limiter. This is a rule of thumb, not a validated threshold. Work on it with technique feedback rather than reaching for the buoy.

Paddles: speed and shoulder risk

Paddles increase the surface area of your hand, so each stroke moves more water. Two studies show how they change the stroke:

• Lopez-Plaza and colleagues (2012) had nine elite swimmers swim 100 m without paddles, with small paddles and with large paddles. Stroke length increased significantly with paddles, speed increased in the second 50 m, and stroke rate tended to fall as paddle size grew.
• De Matos and colleagues (2023) tested 11 competitive male swimmers over 50 m all-out with paddles, fins or no equipment. Both paddles and fins improved arm-stroke efficiency compared with swimming without equipment, and the authors concluded that equipment "deeply modifies the structure" of the stroke.

What these studies show is that paddles change how you swim while you're wearing them. Whether they make you faster without paddles over time isn't clearly established in this evidence.

The more important finding for triathletes is about injury. In a retrospective study of 193 amateur triathletes, Schorn and colleagues (2018) found that paddle use was associated with shoulder overuse injuries. That's an association, not proof that paddles caused the injuries, but it fits with the mechanics: bigger paddles mean more force through the shoulder on every stroke.

Practical guidance, reasoned from the above:

• Start small. Paddles only slightly larger than your hand, not large power paddles.
• Small doses. A few hundred metres a week to begin with, built gradually.
• Use them for a reason: to feel the catch, or for short strength-endurance sets, not as default kit.
• Stop at the first sign of shoulder pain, and don't use paddles at all during a ramp-up in swim volume.

Fins: kick technique and speed

Fins reduce the energy cost of kicking and increase distance per kick, as Zamparo's study showed. In the De Matos study, fins produced the fastest 50 m times and highest speeds, increased stroke length and reduced kick amplitude, but energy cost at those all-out speeds was significantly higher.

For triathletes, fins have a few sensible uses, again reasoned rather than tested:

• Kick technique: short fins make it easier to feel a compact kick from the hip rather than from the knee.
• Ankle flexibility: many triathletes have stiff ankles from running and cycling, which limits the kick. Fins may help them feel the right foot position, although they don't directly improve flexibility.
• Speed work: short sprints with fins let you rehearse a faster stroke rate with good form.

Fins add load to the ankles, knees and hips. Build kick-with-fins sets gradually.

Snorkels

Centre-mounted snorkels let you swim without turning to breathe, which removes one of the biggest disruptions to many triathletes' strokes. They're useful for isolating head position, body alignment and the catch. We didn't find controlled research on snorkel training, so this is coaching practice. The obvious limitation is that you have to breathe in races, so snorkel work should be balanced with practice of your actual breathing pattern.

Building a better kick: an example progression

If kick work is new to you, here's one way to build it over 6-8 weeks. It's coaching practice, loosely modelled on the idea of training a steady, rhythmic kick, and not the protocol used in the Ambrosini study, which the abstract doesn't describe in detail.

• Weeks 1-2: 4-6 × 25 m kick with short fins, on your side or with arms extended, long rest. Focus on a compact kick from the hip, relaxed ankles and minimal knee bend.
• Weeks 3-4: 6-8 × 25-50 m kick, alternating with and without fins. Add 4 × 50 m of full stroke concentrating on keeping a light, continuous kick rhythm.
• Weeks 5-6: 6 × 50 m full stroke, counting kicks per arm cycle to practise a steady pattern. A six-beat rhythm is the one tested in the triathlon study, but a steady two- or four-beat kick that keeps your hips up may suit some athletes better.
• Weeks 7-8: include a few minutes of rhythmic kicking within threshold sets, so the kick holds under fatigue.

Keep total kick volume modest, and stop any set that causes knee or ankle pain.

Who these studies tested

It's worth being clear about who's behind these findings, because it affects how much weight they can carry. The kick-contribution study used eight male swimmers. The fins energy-cost study used ten swimmers. The paddle studies used nine elite swimmers and eleven competitive male swimmers. The triathlon kick trial had 15 triathletes, split three ways. The shoulder-injury association comes from a retrospective survey of 193 amateur triathletes, the only data here drawn from age-groupers.

Women are barely represented, masters athletes not at all, and none of these studies tested the long-term effect of a training aid on race performance. That doesn't make the findings useless. The mechanisms they describe are plausible and fit coaching experience. But it means "use toys deliberately and test the effect on your own unaided swimming" is better advice than any fixed rule.

A practical approach to the kit bag

The principle is simple: use each tool for a specific purpose, and do most of your swimming without them. A reasonable starting balance for an age-grouper, which is a judgement rather than a tested ratio, is that equipment makes up no more than about a quarter of weekly distance.

• Kick work: a short block in two sessions a week, with or without short fins, focused on a compact, efficient kick.
• Pull buoy: occasional arm-focused technique or endurance sets, not every session. Check regularly that your unsupported body position is improving.
• Paddles: small paddles, small doses, added gradually, and dropped at any sign of shoulder pain.
• Fins: technique and short speed work.
• Snorkel: technique blocks focusing on head position and alignment.

And always test the effect on your unaided swimming. The goal of every tool is to make your normal stroke, the one you race with, faster or cheaper.

References

• Deschodt VJ, et al. Relative contribution of arms and legs in humans to propulsion in 25-m sprint front-crawl swimming. European Journal of Applied Physiology, 1999;80(3):192–199. doi:10.1007/s004210050581
• Zamparo P, Pendergast DR, Termin A, Minetti AE. Economy and efficiency of swimming at the surface with fins of different sizes and stiffness. European Journal of Applied Physiology, 2006. doi:10.1007/s00421-005-0075-7
• Ambrosini L, Presta V, Vitale M, Menegatti E, Guarnieri A, Bianchi V, De Munari I, Condello G, Gobbi G. A higher kick frequency swimming training program optimizes swim-to-cycle transition in triathlon. Journal of Strength and Conditioning Research, 2024. doi:10.1519/JSC.0000000000004731
• Quagliarotti C, Cortesi M, Gatta G, Bonifazi M, Zamparo P, Baldassarre R, Vleck V, Piacentini MF. Wetsuit use during open water swimming. Does it "suit" everybody? A narrative review. International Journal of Sports Physiology and Performance, 2021;16(9):1217–1224. doi:10.1123/ijspp.2020-0808
• Lopez-Plaza D, Alacid F, Lopez-Minarro PA, Muyor JM. The influence of different hand paddle size on 100-m front crawl kinematics. Journal of Human Kinetics, 2012. doi:10.2478/v10078-012-0070-0
• De Matos CC, Guignard B, De Souza Castro F, Guimard A. Effects of paddles and fins on front crawl kinematics, arm stroke efficiency, coordination, and estimated energy cost. Frontiers in Physiology, 2023. doi:10.3389/fphys.2023.1174090
• Schorn D, Vogler T, Gosheger G, Schneider K, Klingebiel S, Rickert C, Andreou D, Liem D. Risk factors for acute injuries and overuse syndromes of the shoulder in amateur triathletes: a retrospective analysis. PLoS ONE, 2018;13(6):e0198168. doi:10.1371/journal.pone.0198168