The LIFTMOR trial

LIFTMOR is the Australian trial that put women with fragile bones under a heavy barbell and found their spines got denser, not broken. Supervised heavy lifting plus jumping raised spine bone density by about 3% in eight months, the gentle comparison programme lost bone, and there was one minor adverse event. A follow-on trial from the same team found a smaller gain, and neither was large enough to count fractures.

If you have low bone mass, heavy lifting is an option worth discussing, not something to fear — but do it the way the trial did: screened beforehand, coached, and built up gradually. Two exclusions apply: avoid rounding your back, especially under load, and if you have already had a spinal fracture or several low-trauma fractures, keep impact to about brisk-walking level.

What the trial tested

LIFTMOR (Lifting Intervention For Training Muscle and Osteoporosis Rehabilitation) recruited 101 postmenopausal women (49 assigned to heavy training, 52 to the comparison) whose bone density was already low enough to be classed as osteopenia or osteoporosis. They were screened for conditions and medications that affect bone and physical function, then randomly assigned to one of two programmes for 8 months:^[1]

High-intensity resistance and impact training, twice a week, about 30 minutes a session, fully supervised: deadlifts, overhead presses and back squats at 5 sets of 5 reps above 85% of one-rep maximum (the most weight you can lift once), plus jumping chin-ups with firm drop landings. Women worked up to those loads gradually.
A low-intensity home programme as the comparison.

The design was deliberately aggressive. Low-impact exercise had long been the standard advice for people with fragile bones, on the fear that heavy loading would fracture them.

What it found

Spine: bone density rose about 2.9% in the heavy group and fell about 1.2% in the gentle group.
Hip: the femoral neck (the top of the thigh bone, where hips break) gained about 0.3% against a loss of about 1.9%. The thickness of its outer shell also improved.
Function: the heavy group did better on every physical test, including getting up from a chair, reaching and strength, and gained slightly in height while the gentle group lost a little.
Adherence was high: the heavy group attended about 92% of sessions.

Was it safe?

There was one adverse event in the heavy group, a minor lower-back spasm, and no fractures. That result has conditions attached, and they matter if you want to copy it: the women were otherwise healthy, had been screened for bone-affecting conditions and drugs, were supervised throughout, and there were 49 of them in the heavy group over 8 months. That is enough to overturn the blanket fear, not enough to rule out rare harms.

A UK expert consensus adds two exclusions that apply whatever programme you follow. Avoid postures that round the back a lot, in exercise or daily life and especially under load — which is not the same as the neutral-spine hinge of a deadlift. And if you have already had a vertebral fracture or several low-trauma fractures, keep impact to about the level of brisk walking.^[2] Many vertebral fractures cause no symptoms, so a pain-free back is not proof of an intact spine.

The follow-on trial: smaller, and not at the hip

The same group's next trial, MEDEX-OP, gave 115 postmenopausal women with low bone mass either a similar heavy programme (5 sets of 5 at above 80–85% of maximum, 40-minute sessions, twice a week for 8 months) or a low-intensity Pilates-based class. It also split the women by whether they were already taking bone-protective medication.^[3]

Spine density rose 1.9% on the heavy programme against 0.1% on the gentle one — the same direction as LIFTMOR at about two-thirds of the size. Total hip density, a main outcome, did not favour the heavy programme. Women who lifted heavier gained more at the spine. There were seven adverse events across the four groups (four with heavy training, three with Pilates), and the authors called both programmes well tolerated. Neither trial reported a fragility fracture.

What the trials can't tell you

Fractures. Bone density is a stand-in for the outcome that matters, and neither trial was big enough to count broken bones. The fracture evidence comes from pooling trials: across eleven controlled exercise trials covering nearly 20,000 participant-years, exercise cut major osteoporotic fractures by about a quarter. But programmes that increased intensity over time showed no significant advantage, so the pooled fracture data do not show that lifting as heavy as LIFTMOR is necessary.^[4]

Whether heavy is necessary. Pooled trials found heavier loading (70% of maximum or more) helped at the hip but not the spine,^[5] and a 2026 synthesis comparing heavy with lighter loading head-to-head in adults over 50 found no significant bone difference at either site (the spine result was borderline), although strength clearly favoured heavy. It also found no significant difference in adverse events or falls, though both estimates leaned toward more with heavy loading and were very imprecise.^[6]

Who it applies to. Both trials were in postmenopausal women with low bone mass, so the results do not transfer automatically to men or younger women.

What to do

If you have low bone mass, consider heavy lifting with supervision. The trial protocol — squat, deadlift and overhead press, built up to five sets of five at a heavy load, twice a week — is a tested template. Start lighter and progress under a coach.
Keep the impact part. The jumping drop landings were part of what LIFTMOR tested; daily hopping is covered in Impact exercise.
Respect the two exclusions above, and get a clinician's view first if you have had a fracture.
Keep going. In one trial, the spine advantage from training was gone three months after stopping; see Bone density for the full programme.