REF-1637 · Jay et al., 2011 · Scandinavian Journal of Work, Environment & Health · Paper · PubMed

Eight weeks of ballistic kettlebell training at the workplace, three times a week, eased neck/shoulder pain by 2.1 points (95% CI −3.7 to −0.4, 0-10 scale) and low-back pain by 1.4 points against controls and strengthened the trunk extensors, but left aerobic fitness unchanged, in 40 adults from pain-prone jobs (mean age 44, 85% women)

Main caveat: One worksite trial of 40 workers with existing pain over 8 weeks; not athletes.
moderate evidenceMeasured on non-athletes and recreational peopleRead from the abstract only

Jay and colleagues tested whether kettlebell training at work improves musculoskeletal and cardiovascular health.

Forty adults whose occupations carry a high rate of reported musculoskeletal pain (mean age 44, BMI 23 kg/m², 85% women; baseline pain 3.5 of 10 in the neck/shoulders and 2.8 in the low back) were randomised to ballistic, whole-body kettlebell exercise three times a week for 8 weeks or to a control group, and an assessor blinded to group measured them before and after.

The main outcomes were neck/shoulder and low-back pain intensity, isometric muscle strength and aerobic fitness. Against control, training cut neck/shoulder pain by 2.1 points and low-back pain by 1.4 points and raised trunk-extensor strength; trunk-flexor and shoulder strength did not rise more than in controls, and aerobic fitness stayed where it was.

The authors conclude that the programme reduces neck/shoulder and low-back pain and strengthens the low back in these workers, while it "does not appear to improve aerobic fitness".

Participants

n = 40 adults from occupations with a high reported rate of musculoskeletal pain; mean age 44 y, BMI 23 kg/m², 85% women.
Baseline pain intensity (0-10 scale): neck/shoulders 3.5, low back 2.8.
Not in the abstract: group sizes, the occupations, training or activity history, dropouts, baseline aerobic fitness.

Protocol

Random allocation to training or control; single-blind, with a blinded assessor at baseline and follow-up.
Training: ballistic whole-body kettlebell exercise at the worksite, 3 sessions a week for 8 weeks.
Control: what the control group did is not in the abstract.
Outcomes: pain intensity in the neck/shoulders and low back; isometric strength of the trunk extensors, trunk flexors and shoulders; aerobic fitness.
Not in the abstract: the exercises, kettlebell mass, sets and work bouts, session length, supervision, adherence, how aerobic fitness was tested.

Key Results

Outcome, training vs controlResult
Neck/shoulder pain (0-10)−2.1 points (95% CI −3.7 to −0.4)
Low-back pain (0-10)−1.4 points (95% CI −2.7 to −0.02)
Trunk-extensor strengthincreased (P < 0.001)
Trunk-flexor and shoulder strengthno increase vs control
Aerobic fitnessunchanged
The abstract gives no values for strength or aerobic fitness, only the direction.

Practical Application

At this dose, ballistic kettlebell work built the back, not the engine. Eight weeks of ballistic kettlebell work three times a week strengthened the trunk extensors and eased neck/shoulder and low-back pain in workers, but aerobic fitness did not move; plan kettlebell work as strength work, not as a stand-in for an aerobic session.
Inference, not tested here: a back-strength option for riders and runners. The trunk-extensor gain is the result most relevant to an endurance athlete; cyclists with low back pain had weaker back-extensor endurance in a review of small studies (REF-1266), but no trial here tests kettlebells in athletes or for back pain on the bike.
Pain that is new, severe, getting worse, or comes with leg symptoms goes to a clinician. The assistant does not diagnose back or neck pain; this trial enrolled workers with existing low-grade pain (3.5 and 2.8 of 10) and says nothing about acute injury.
Not settled by this design: whether a harder kettlebell protocol (heavier bells, longer work bouts, shorter rests) raises aerobic fitness, since the load, session length and aerobic test are not in the abstract and two groups of about 20 can miss a small change; other kettlebell studies are in REF-1635 and REF-1636.

Limitations

One worksite trial of 40 workers with existing pain over 8 weeks; not athletes.
Exercises, load, session length, adherence and the aerobic test are not in the abstract; the aerobic null comes without numbers.
What the control group did is not described in the abstract, and participants knew whether they trained (single-blind design).
The PubMed subject terms ("Male" only) conflict with the abstract's 85% women; the abstract is taken as correct.
Written from the abstract and the PubMed record; full text not read.
How this entry was checked and changed
Why this level

parallel RCT, 40 randomised to two groups (20 per arm by the rubric's division; group sizes not in the abstract); a trial with ≥20 per arm reaches A- only when read in full, so risk of bias not read (abstract only)

Content correction 2026-11-07
2026-11-07: added from the abstract and the PubMed record; level B+ (parallel RCT, 40 in two arms; risk of bias not read, abstract only).