The short answer
Your heart rate overstates the work
In one study, ten college men did as many two-handed swings with a 16 kg kettlebell as they could in 12 minutes. Heart rate averaged 87% of maximum, which looks like hard cardio. But oxygen use, the thing VO2max measures, averaged only 65% of their VO2max1.
The researchers concluded swings are intense enough to train VO2max, but warned that heart rate runs well ahead of actual oxygen demand during kettlebell work1. If you train by heart rate zones, expect them to flatter a kettlebell session.
A kettlebell routine that raised VO2max
Seventeen college soccer players trained three days a week for four weeks, on top of their normal off-season training2:
| Group | Session | VO2max change |
|---|---|---|
| Kettlebell | 20 minutes of snatches, 15 s work and 15 s rest | Up 2.3 ml/kg/min (about 6%) |
| Circuit weights | 20 minutes of free-weight and body-weight exercises in a continuous circuit | No significant change |
The difference was the structure: the snatch routine was a long interval session done with a kettlebell. Each player's workload was set from a snatch test beforehand2.
When kettlebells did not move it
In a workplace trial, adults with neck, shoulder and back pain did eight weeks of full-body kettlebell training, three times a week. Pain dropped and back strength improved, but aerobic fitness did not change3. Kettlebell training is not automatically cardio training; how you program it decides what it builds.
How to set up a kettlebell VO2max circuit
Use simple, explosive hip movements
Two-handed kettlebell swings to start; one-arm swings or snatches once your technique is solid. These let you move fast for a long time without the technique demands of more complex lifts.
Run it as intervals
| Level | Session |
|---|---|
| Starting out | 10 min of 15 s swings, 15 s rest |
| Building | 15 min of 15 s swings or snatches, 15 s rest |
| Full session | 20 min of 15 s snatches, 15 s rest, as in the study above |
Choose a weight you can move fast
The goal is steady, quick reps for the full session, not the heaviest bell you can swing. If your reps slow down badly or your hips stop snapping through, the bell is too heavy for this.
Stop before your form breaks
End the set if your lower back starts to round or take over from your hips, or if your grip is about to fail. A dropped or wild bell is the main risk in this kind of session.
Try this workout
Kettlebell intervals for VO2max
Who it is for: People who can already swing a kettlebell with good form, as a second hard session or when they cannot run.
- 1Warm up. A few light sets of swings, building the hip snap.
- 2Main set. 10 minutes of 15 seconds of two-handed swings, 15 seconds rest.
- 3Build up. Add 5 minutes every week or two, up to 20 minutes of 15-second snatches with 15 seconds rest: the routine that raised VO2max about 6% in four weeks, three times a week 2.
- 4Stay safe. Use a bell you can move fast for the whole session, and end a set if your lower back takes over or your grip is about to fail.
Put it into practice
Sources
All research- 1Oxygen cost of kettlebell swingsFarrar et al., 2010. Journal of Strength and Conditioning Research 24(4):1034-1036.
- 2Effects of kettlebell training on aerobic capacityFalatic et al., 2015. Journal of Strength and Conditioning Research 29(7):1943-1947.
- 3Kettlebell training for musculoskeletal and cardiovascular health: a randomized controlled trialJay et al., 2011. Scandinavian Journal of Work, Environment & Health 37(3):196-203.
General fitness information, not medical advice. If you have an injury or a health condition, check with a professional before starting a new kind of training.