Is kettlebell training cardio or strength?

Is kettlebell training cardio or strength? It is a strength and power stimulus that runs at a cardio heart rate. Across 12 minutes of swings with a 16kg (35lb) bell, ten men averaged 86.8 percent of maximum heart rate while drawing only 65.3 percent of their peak oxygen uptake. Both halves are real. The aerobic half is smaller than your heart rate makes it feel.

That gap is the whole argument of this page. During kettlebell work, heart rate overstates oxygen cost — which is why "kettlebells are cardio" keeps being half-true, and why eight-week kettlebell trials keep returning strength gains next to flat aerobic numbers.

If you have not bought a bell or run a session yet, Exercise Legend's kettlebell guide covers the equipment, movements and frequency questions this page skips. What follows is only the cardio-versus-strength ledger.

One caution before any of it. McGill and Marshall, in the Journal of Strength and Conditioning Research, concluded that "the large shear to compression load ratio on the lumbar spine created during swing exercises suggests that this training approach may be contraindicated for some individuals with spine shear load intolerance." Conditioning work means many reps performed tired, which is when a hinge is most likely to degrade. If you have a history of back pain, that decision belongs with a clinician or physiotherapist, and are kettlebell swings bad for your back sets out what has and has not been measured.

Why your heart rate lies during kettlebell work

The cleanest demonstration is the simplest study. Farrar, Mayhew and Koch, in the Journal of Strength and Conditioning Research, had 10 college-aged men perform as many two-handed swings as they could in 12 minutes with a 16kg (35lb) bell, with expired gases collected throughout. The men completed an average of 265 swings. Average heart rate landed at 165 beats per minute, which was 86.8 percent of their maximum. Average oxygen uptake was 34.31 ml/kg/min — 65.3 percent of the VO2max they had already recorded on a graded exercise test to exhaustion. That gap was statistically significant, and the authors state it plainly: "Heart rate was substantially higher than Vo2 during kettlebell swings."

A monitor reading 87 percent of max tells you how hard your cardiovascular system is working. It does not tell you how much oxygen you are using. They track each other when you run or cycle. Under load, gripping and bracing, they come apart.

The decoupling shows up from both directions. Hulsey and colleagues, in the same journal, had 13 subjects complete a 10-minute swing routine on a 35-seconds-on, 25-seconds-off clock — 16kg (35lb) for men, 8kg (18lb) for women — and then, 48 hours later, run on a treadmill at the same rating of perceived exertion. Heart rate came out effectively identical: "Average HR and RPE were not significantly different between KB and TM and averaged 90 and 89%, respectively, of age-predicted HRmax." Everything metabolic did not: "Oxygen consumption, METS, pulmonary ventilation, and calorie expenditure were significantly higher for TM (25-39%) than for KB."

Run it the other way and you get the mirror image. Thomas and colleagues matched a 30-minute session of swings and sumo deadlifts against graded treadmill walking at the same measured oxygen uptake in 10 novice volunteers. Oxygen cost, respiratory exchange ratio and blood pressure came out similar, "but RPE and heart rate were greater during KB exercise."

Why? The usual explanation is the pressor response: heart rate and blood pressure driven up by muscular effort rather than by oxygen demand. The direct evidence comes from barbell work. Collins, Cureton, Hill and Ray, in Medicine and Science in Sports and Exercise, measured heart rate and oxygen uptake in 15 men lifting at 40, 50, 60 and 70 percent of one-rep max. Oxygen uptake sat at 33 to 47 percent of treadmill VO2max while heart rate sat at 63 to 82 percent of maximum. The slope relating the two "was approximately half that reported for dynamic low-resistance exercise such as running or cycling". Their conclusion is the one that matters for programming: using heart rate to prescribe the metabolic intensity of weight lifting "results in a substantially lower level of aerobic metabolism than during dynamic low-resistance exercise."

Read the limit, which Meigh's review states for us. Writing about kettlebells specifically, the authors note that "Physiological mechanisms for the pressor response (disproportionately elevated HR when compared to oxygen consumption during resistance training) have been proposed, however these claims have not been validated in practice". So the pattern is measured repeatedly. The mechanism, applied to kettlebells, is still an inference.

What the strength side of the ledger looks like

Stronger, and better documented. Ballistics sit almost exactly where ACSM's power recommendation lives: ACSM's summary of its 2026 position stand on resistance training advises moderate loads of 30 to 70 percent of one-rep max for power, and tells you to "emphasize moving the weight as quickly as possible during the concentric (lifting) phase." That is a description of a swing.

The mechanical demand has been quantified. Lake and Lauder, in the Journal of Strength and Conditioning Research, had 16 men swing 16, 24 and 32kg bells on a force plate alongside back squats and jump squats, and found the highest net impulse of the protocol came from the 32kg swing: 276.1 newton-seconds against 182.8 for a back squat at 60 percent of one-rep max. Peak force was generally higher in the squats, but swing power exceeded back-squat power. The authors' summary: "These findings indicate a large mechanical demand during swing exercise".

Training studies follow. In a separate trial, Lake and Lauder randomised 21 healthy men to swing training or jump squat training twice a week, the swing group doing 12 rounds of 30 seconds on and 30 seconds off with 12kg (26lb) under 70kg of body mass and 16kg (35lb) above it. "Maximum strength improved by 9.8%" on the half-squat one-rep max and "Explosive strength improved by 19.8%" on vertical jump height, with no significant difference between the two training methods. The ACE-commissioned eight-week study at the University of Wisconsin-La Crosse measured a 41.7kg rise in leg press and a prone plank going from 1:05 to 1:50 against 12 controls. Jay and colleagues in the Scandinavian Journal of Work, Environment and Health found that after eight weeks of ballistic kettlebell training, "the training group increased muscle strength of the trunk extensors", though not the trunk flexors or shoulders.

The ceiling is real, and the one head-to-head trial against barbell weightlifting finds it. Otto and colleagues randomised 30 healthy men to six weeks of weightlifting or kettlebell training and reported that "short-term weightlifting and kettlebell training were effective in increasing strength and power" — but also that "6 weeks of weightlifting induced significantly greater improvements in strength compared with kettlebell training." Six weeks is short, 30 men is small, and maximum strength was tested with the back squat, which only one group trained. Can kettlebell training build muscle handles the size question separately.

Are kettlebell workouts HIIT?

Structurally, usually yes. Definitionally, not always — and the gap is instructive.

The American Council on Exercise's guide to HIIT for clinical populations, written by Lance Dalleck, Ph.D., defines it this way: "High-intensity interval training (HIIT) involves alternating brief bouts (30 seconds to 5 minutes) of higher-intensity sessions with either rest or lower-intensity workloads throughout an exercise routine."

Now look at the protocols the research actually used. Hulsey's swing routine ran 35 seconds on, 25 off. Lake and Lauder's training arm ran 30 on, 30 off. The ACE snatch study and the Falatic trial both ran 15 on, 15 off. Most of those work bouts sit at or below the bottom of ACE's own definitional range. Kettlebell conditioning is interval training, but it is usually built from intervals shorter than the HIIT literature was written around — our editorial reading of the protocol list, not a published finding.

The intensity is not in doubt. ACE's snatch study — the Wisconsin-La Crosse team under John Porcari and Chad Schnettler, 10 experienced volunteers aged 29 to 46 — reports that "The average heart rate during the kettlebell snatch workout was between 86 percent and 99 percent of the kettlebell heart rate max."

That study also produced kettlebell marketing's most-quoted number, and it needs handling. ACE reports that "volunteers burned an average of 272 calories which turns out to be 13.6 calories a minute" across the 20 minutes, then adds an estimate of anaerobic cost from blood lactate — another 6.6 calories per minute — to reach roughly 20.2, which it calls "equivalent to running at a 6-minute mile pace". Neither number was measured directly. Chad Schnettler's underlying thesis records that "Only HR was measured" during the 20-minute workout, with oxygen uptake and so the 13.6 derived from a heart rate/VO2 regression equation built during a separate 5-minute snatch test, and notes that energy expenditure was likely underestimated because anaerobic energy expenditure could not be calculated accurately. Our reading: cite 13.6 and treat 20.2 as an upper bound, not a headline.

The same study carries the finding this article turns on. ACE's write-up states that "the treadmill VO2max was 23 percent higher (38.9 ml/kg/min vs. 31.6 ml/kg/min) than the VO2max attained during the kettlebell VO2max test." The thesis reports a 23 percent gap too, but from different absolute values — 49.7 ml/kg/min on the treadmill against 40.3 on the kettlebell snatch test. We cannot reconcile the two, so we are flagging the discrepancy rather than picking one. The direction holds either way: test maximum oxygen uptake with a kettlebell and you get a lower number than on a treadmill. The limiter is not your heart and lungs.

What eight weeks of swinging does to aerobic fitness

In the best-known randomised trial, nothing measurable. Jay and colleagues ran a single-blind randomised controlled trial in 40 adults drawn from occupations with a high prevalence of musculoskeletal pain — mean age 44, 85 percent women — assigning them to ballistic full-body kettlebell exercise three times a week for eight weeks or to a control group, with a blinded assessor taking measures at both ends. The result on the aerobic outcome is one sentence long: "Aerobic fitness remained unchanged." Their conclusion repeats it: "This type of training does not appear to improve aerobic fitness."

Say what that does and does not establish. It was eight weeks, three sessions a week, in mostly female workers in their forties recruited for their occupational pain risk rather than for an aerobic goal. The same trial found neck and shoulder pain down 2.1 points and low back pain down 1.4 points on a 0 to 10 scale, plus the trunk extensor gain — so this was not a trial where nothing happened. The honest reading is that this dose, in this population, over this period, did not move aerobic fitness. It is not evidence that kettlebell conditioning cannot.

When kettlebell conditioning did move oxygen uptake

Other trials did move it, and which ones did is the useful part.

• Snatches on a 15:15 clock, four weeks. Falatic and colleagues assigned 17 female NCAA Division I soccer players to kettlebell snatching or a circuit weight-training control, three days a week for four weeks on top of their off-season programme. The kettlebell group gained an average of 2.3 ml/kg/min of VO2max, roughly 6 percent; the control group did not change significantly. The authors concluded the protocol "significantly improved aerobic capacity in female intercollegiate soccer players". Nine athletes in the training arm is a small sample, and these were trained players adding work to an existing programme.
• Eight weeks of classes. The ACE-sponsored training study put 18 volunteers aged 19 to 25 through hour-long kettlebell classes twice a week for eight weeks against 12 controls, and recorded VO2max rising from 36.3 to 41.3 ml/kg/min. Porcari's quoted summary: "Yet, we saw a 13.8 percent increase in aerobic capacity." The limit beside it is ours rather than the authors': aerobic capacity there was assessed with "a modified kettlebell snatch test", so eight weeks of practising snatches may have improved the test as well as the athlete. The same write-up records that "Researchers saw no significant changes in body composition (body weight, sum of skinfolds and percent body fat) for either group over the course of the study."
• Ten weeks, no control group. Zimerer and colleagues, in the Journal of Chiropractic Medicine, took 14 recreationally active women with no kettlebell experience through a 10-week progressive programme and measured maximum strength up 23.73 percent and VO2max up 9.63 percent. One group, no comparison arm — a plausible signal rather than a result.

The review that read all of this is appropriately unexcited. Meigh and colleagues identified 829 records to February 2019, included 99 publications, and reported that across the longitudinal literature, "Effect sizes were typically trivial to small" and "Confidence in reported effects is low to very low." On conditioning, their verdict runs in three parts worth quoting together: "Kettlebell training appears to induce a cardiometabolic response sufficient to improve cardiovascular fitness"; "Effects have often been over-reported, and reliable clinically meaningful effects remain to be demonstrated in a high quality randomised controlled trial"; and "hardstyle kettlebell training is not the most effective form of exercise for improving cardiovascular capacity". They close with the sentence that best describes the state of play: "The long-term cardiometabolic effects of kettlebell training remain equivocal."

How to program for one adaptation instead of neither

The common failure is not choosing. A circuit heavy enough to feel like lifting and long enough to feel like running is often too light to drive strength and too interrupted to drive aerobic fitness. Decide what each session is for before you pick up the bell.

• Give every session one job. Strength days use grinds — presses, rows, front squats, carries — at low reps with real rests, because ACSM's strength figure is "80% of one-repetition maximum (1RM)" and you cannot approach that on a clock. Conditioning days use ballistics on a timer. Our four-week starter plan, kettlebell workouts for beginners, splits them this way on purpose.
• Stop using heart rate as the dial for bell work. At a given percentage of maximum heart rate, Collins and colleagues found oxygen uptake during lifting runs well below what the same heart rate would mean on a treadmill. Score conditioning sessions by work completed — rounds, reps, bell size, total time — not by how high the watch went.
• Keep some genuinely aerobic work if VO2max is the goal. ACSM's 2011 position stand asks most adults for at least 150 minutes a week of moderate-intensity cardiorespiratory exercise or at least 75 minutes of vigorous-intensity exercise, plus resistance exercise for the major muscle groups two to three days a week. Nothing we read argues for dropping the first half.
• Mind how much endurance work sits next to your strength work. The meta-analysis by Wilson and colleagues, covering 21 studies and 422 effect sizes, found that "resistance training concurrently with running, but not cycling, resulted in significant decrements in both hypertrophy and strength", with negative correlations between endurance frequency and duration and gains in strength, power and size. Their conclusion: "interference effects of endurance training are a factor of the modality, frequency, and duration of the endurance training selected."
• Let technique end the conditioning set. On ballistics the limiter is usually grip, breathing or the hinge, not your cardiorespiratory system — part of why kettlebell VO2max tests return lower numbers than treadmill tests. Porcari's advice in ACE's write-up is worth repeating: "Good form is key to avoiding injury."

None of this is a prescription for an individual. If you are managing heart or blood-pressure conditions, a back or shoulder problem, pregnancy or recovery from surgery, the intensity question belongs with a clinician first.

The honest verdict

Kettlebell training is strength and power work first, with a conditioning effect that is genuine, modest and easy to overstate because your heart rate reports it so loudly. The numbers to carry away: 86.8 percent of maximum heart rate at 65.3 percent of VO2max during 12 minutes of swings; oxygen cost and calorie burn 25 to 39 percent higher on a treadmill than in swings at matched perceived exertion; roughly 6 percent VO2max gain from four weeks of snatch intervals in trained athletes; and no measurable aerobic change after eight weeks of ballistic kettlebell training in a 40-person randomised trial.

So choose. If you want strength and power from one bell in a small space, the evidence supports you and the sessions should look like lifting. If you want aerobic fitness, kettlebell intervals can contribute, and in our reading they are not the most efficient tool available — the review literature says the same more carefully. What the evidence does not support is a permanent middle zone scored by heart rate.

If you are earlier in the series, start a level up: Exercise Legend's beginner kettlebell guide covers the bell, the patterns and the weekly structure everything above assumes.