Jumps or Iron? What Plyometric Training Really Does for Triathlon Run Speed

If you've spent five minutes scrolling triathlon gym content, you've seen the pitch: a few sets of box jumps or ankle hops before your run, twice a week, and you'll unlock "free speed." It's a tidy story, and Triathlete has run a version of it, promoting a 5-minute plyometric warm-up on the premise that twice-weekly plyos improve running economy. The trouble is that when you actually read the studies behind that claim, the picture is a lot more conditional than the reels suggest. This article walks through what the evidence really shows about plyometric training and running economy, where it genuinely helps, where heavy resistance training still wins, and how to add jump work sensibly on top of a running and cycling volume that's already taxing your tendons and joints.

Why this question matters for age-group triathletes

Running economy — how much oxygen you burn to hold a given pace — is one of the few physiological levers age-group triathletes can meaningfully train, alongside aerobic capacity and threshold. Anything that plausibly improves economy without adding fatigue is attractive, because most of us are not short on run mileage; we're short on the hours to add more of it. Plyometrics fit that appeal perfectly: short, punchy, easy to film for a 30-second video, and framed as a shortcut that traditional heavy lifting supposedly can't match.

That framing deserves scrutiny for two reasons. First, triathletes already carry a heavier orthopedic load than most single-sport runners, because the run leg happens on already-fatigued tissue after swimming and biking. A systematic review of injuries in long-distance triathletes found overuse injury incidence ranging from 37% to 91% across studies, with the knee, lower back, and ankle/foot the most commonly affected sites — evidence that adding impact work casually is not a neutral decision (systematic review of long-distance triathlon injuries, PMC). Second, "improves running economy" and "makes you faster in a triathlon" are not the same claim, and most of the plyometrics content blurs the two. Before you add jump work to an already full week, it's worth knowing exactly what has and hasn't been shown, and for whom.

What the evidence actually says

Heavy resistance training beats plyometrics for running economy, on average

The most direct answer to "jumps or iron" comes from a meta-analysis that compared the two approaches head-to-head. Pooling 14 studies of heavy resistance training and 8 studies of plyometric training, with mean intervention lengths of 9.6 and 6.9 weeks respectively, heavy resistance training produced a small but real improvement in running economy (Hedges' g = −0.32, 95% CI −0.55 to −0.10), while plyometric training alone produced a trivial effect that could not be distinguished from no effect (g = −0.13, 95% CI −0.47 to 0.21) (Heavy Resistance Training Versus Plyometric Training for Improving Running Economy, Sports Medicine – Open / PMC). In plain terms: on average, across the pooled research, loading a barbell did more for your running economy than hopping did, and the plyometric effect was small enough that it's not clearly different from zero.

That's a useful corrective to the "jumps for free speed" pitch, but it isn't the whole story, and a single pooled number can hide meaningful nuance underneath it — which is exactly what the next two studies reveal.

Plyometrics may still help, but mostly at the paces most age-groupers actually run

A 2024 review in *Sports Medicine* examined strength training methods across a range of running speeds and found that plyometric training improved running economy only at speeds of 12.00 km/h or slower (effect size = −0.307, p = 0.028, rated moderate certainty). High-load resistance training (≥80% of one-rep max), by contrast, improved economy across a much wider band from 8.64 to 17.85 km/h, with the benefit growing larger at faster speeds (Sports Medicine, 2024).

This is the detail that actually matters for most of the people reading this. A 12 km/h pace is 5:00/km, or roughly an 8:03/mile — solidly in the easy-to-moderate range for the bulk of age-group triathletes, especially off the bike. If you run at or below that pace for most of your training and racing, you're sitting squarely in the speed band where plyometrics showed a real, if moderate-certainty, benefit. If you're a faster age-grouper running well under 5:00/km pace, the evidence tilts more clearly toward heavy loading as the higher-value use of your gym time. Neither finding licenses the claim that jump training "makes you faster" in general — it's a speed-dependent effect from a single moderator analysis, not a guarantee.

Jump training plus resistance training may beat either alone — but the "large effect" comes with caveats

A dedicated meta-analysis of plyometric jump training and running economy found a trivial standalone effect (effect size = 0.19) that echoes the head-to-head finding above. But when jump training was combined with resistance training, the pooled effect size jumped to 1.34 — a large effect by conventional benchmarks. Results were better after more than 15 sessions, more than 7 weeks of training, more than 2 sessions per week, and in younger, more highly trained runners working at faster velocities (plyometric jump training and running economy, Kinesiology, 2023).

This is genuinely useful and genuinely counter-narrative for anyone deciding between 20 minutes of hopping and 20 minutes of squats: it suggests the real answer isn't "jumps or iron" but "iron, with jumps layered carefully on top, sustained for long enough." The caveat writers (and readers) need to hold onto is that this large combined-training effect comes from a subgroup analysis inside a broader meta-analysis, not from a single dedicated trial designed to test the combination. It's a real and consistent signal across the pooled data, but it's not the same level of evidence as a purpose-built randomized trial, and the "better after >15 sessions, >7 weeks" dosing detail is itself descriptive of the underlying studies rather than a prescription that's been tested against alternatives.

The one triathlon-specific trial: better neuromotor control, not better running economy

Nearly everything above comes from general endurance-running research, not triathlon research specifically — an important distinction, because triathletes run on fatigued, post-cycling legs, not fresh ones. There is exactly one randomized trial that tested plyometrics in triathletes directly, and it's small and sobering. Researchers screened 15 moderately trained triathletes for aberrant neuromotor control while running after cycling; only 8 showed the abnormal pattern and were randomized into the trial. Eight weeks of added plyometric training improved neuromotor control during running-after-cycling in that group, but running economy did not differ between the plyometric group and the control group (plyometric training and neuromotor control after cycling in triathletes, BJSM/PubMed).

Two things are worth sitting with here. First, an 8-person randomized sample is not enough to draw firm conclusions about triathletes generally — treat this as a signal worth watching, not settled science. Second, and more importantly for how you use this information: the outcome that improved was movement control after the bike-to-run transition, not economy or speed. If your goal in adding plyometrics is "run better after cycling" rather than "run more efficiently in the abstract," this is the most relevant piece of evidence you have, even though it's thin. If your goal is a faster off-the-bike split, the honest answer from this trial is that plyometrics didn't move that needle for these athletes over 8 weeks.

Mechanistically, plyometrics and heavy lifting are training different things

A useful way to hold all of the above together, rather than as contradictory findings, comes from a coaching-oriented explainer on the mechanisms: heavy resistance training primarily improves musculotendinous stiffness and force production capacity, while plyometrics target the stretch-shortening cycle — the tendon's ability to store and return elastic energy quickly during ground contact (Strength Training, Plyometrics and Running Economy, TrainingPeaks). These are related but distinct qualities, which is consistent with why combining them outperforms either alone in the pooled data above — they're not fully redundant, they're complementary, and it's plausible that most age-groupers are more likely to be limited on the "force production and stiffness" side than the "elastic return" side, given how little heavy loading most triathletes do in the first place.

Practical application: what this means for your training

Put together, the evidence supports a fairly specific and fairly cautious recommendation, not a blanket "jump more" or "jump never":

• If you're choosing where to spend limited gym time and can only pick one, heavy, low-rep loaded strength work (squats, deadlifts, step-ups, calf raises) has the stronger and more consistent evidence base for running economy, and it benefits a wider range of paces.
• If you're already doing that heavy strength work consistently and have a stable technical base, layering in a small amount of plyometric work is where the "combined" effect becomes relevant — but the dosing detail (>15 sessions, >7 weeks, >2x/week) suggests this needs sustained, structured exposure, not a one-off circuit before a run.
• If most of your training and racing happens at an easy-to-moderate pace (roughly 12 km/h / 5:00 per km or slower), you're in the specific speed band where the evidence for a plyometric benefit is most direct.
• Don't expect plyometrics, on their own, to fix your off-the-bike run split. The one triathlon-specific trial suggests a possible benefit to movement control after cycling, not to economy or pace — a reasonable thing to try if you notice you run clumsily off the bike, but not a proven speed intervention.

Common mistakes to avoid

• Starting with drop jumps or depth jumps. These are the highest-impact end of the plyometric spectrum and require an established technical and strength base. If you haven't been doing any jump training, start with low-intensity, ground-contact-limited work — pogo hops, low-amplitude bounds — and earn your way toward higher-impact variations over weeks, not days.
• Adding plyometrics in the same week you increase run volume. Impact load is impact load, regardless of source. Stacking a new jump session on top of a bump in weekly mileage is one of the more avoidable ways to trigger an overuse injury, and long-distance triathletes already report overuse injury rates as high as 37–91% depending on the study population (PMC systematic review).
• Training through Achilles, patellar, plantar, or bone-stress symptoms. Plyometrics load exactly the tissues most commonly injured in triathletes. Any of these symptom patterns is a reason to pause jump training, not push through it.
• Treating a small subgroup finding as a broad promise. The large combined-training effect size in the Kinesiology meta-analysis is a genuine, useful signal, but it's a subgroup result, not a dedicated head-to-head trial. Don't repeat it as "plyometrics plus lifting will transform your running" — it's closer to "there's reasonable evidence this combination is worth trying if your foundation is solid."
• Skipping the strength foundation to jump straight to jumps. If your goal is running economy and you have to choose a starting point, the data favors heavy loading first, plyometrics second — not the reverse.

How to apply this in the next week

If you want to test this sensibly without disrupting your current training block:

• Audit your current gym work. If you're doing no loaded strength training at all, that's the higher-value gap to close first, before adding any jump work — the evidence for heavy resistance training and running economy is both stronger and more broadly applicable across paces.
• If you already lift 1–2x/week consistently and are asymptomatic, add a short, low-impact plyometric block (5–10 minutes) after your strength session, twice weekly — not before a hard run, and not in a week where run volume is also increasing.
• Start conservative on impact. Begin with low-amplitude hops and pogo jumps for 2–3 weeks before considering higher-impact variations like bounds or box jumps, and only progress if you remain free of Achilles, knee, plantar, or shin symptoms.
• If you notice you run noticeably worse or clumsier off the bike than off fresh legs, that's the specific scenario the triathlon trial addressed — a modest, consistent plyometric block over 8+ weeks is a reasonable experiment, with the expectation of better movement control rather than a faster split.
• Get technique coaching before adding higher-impact variations. A physiotherapist or qualified strength and conditioning coach can check your jumping and landing mechanics before you load them further, particularly if you have any history of lower-limb injury or bone-stress issues.

References

• A 5-Minute Plyometric Warm-Up to Unlock Your Running Power (Triathlete)
• Heavy Resistance Training Versus Plyometric Training for Improving Running Economy and Running Time Trial Performance (Sports Medicine – Open / PMC)
• Effect of Strength Training Programs in Middle- and Long-Distance Runners' Economy at Different Running Speeds (Sports Medicine, 2024)
• Effects of plyometric jump training on running economy in endurance runners: systematic review and meta-analysis (Kinesiology, 2023)
• Plyometric training as an intervention to correct altered neuromotor control during running after cycling in triathletes: preliminary RCT (PubMed)
• Strength Training, Plyometrics and Running Economy (TrainingPeaks coach blog)
• A Systematic Review of Long-Distance Triathlon Injuries (PMC)