The LIFTMOR trial studied working loads above 85% of a one-rep maximum for 5 sets of 5 under close supervision. That is a study protocol, not an individual starting dose or a required destination. Too Fit to Fracture discusses general strength work of 8–12 repetitions at an effort of 5–8 on a 0–10 scale, starting lower for people who are sedentary, new to strength training or at high fracture risk. Agree on technique practice, loading and any progression with a qualified professional; elapsed app weeks do not establish readiness.
What does “80–85% of your one-rep max” actually mean?
One-repetition maximum (1RM) is a reference measure of the heaviest single repetition assessed for a particular movement. A percentage describes part of that reference load: 80% means four fifths. It does not guarantee a particular repetition count or effort; capacity varies between people and movements. LIFTMOR studied 5 sets of 5 at working loads above 85% under close supervision. Those study conditions are not an app starting dose or instructions to test a maximum alone.
What does the loading research show?
LIFTMOR supports the combined high-intensity resistance and impact program tested in its screened, closely supervised participants. It did not isolate five hard repetitions against twenty easy ones. Repetition count or perceived effort alone cannot predict a BMD change. Appropriate resistance exercise can use body weight, bands, machines or free weights; your starting load, technique practice and progression depend on individual assessment. Keep appropriate weight-bearing activity and balance work in the wider care conversation.
How do you judge load without testing a true one-rep max?
Ask a qualified professional whether any maximum-load assessment is needed and which submaximal method suits you. Repetition-based estimates are approximate and vary with the person and movement; they should not be treated as exact conversions or an instruction to lift to failure. Perceived effort is another discussion tool. Bone Builder uses RPE, or rating of perceived exertion, on a 0–10 reference scale to record how hard a set felt. An effort rating cannot verify technique, assess an injury or establish clinical readiness.
| What you're training | Reps per set | Effort (RPE 0–10 unless noted) | How to apply the example |
|---|---|---|---|
| Learning a new movement | 8–12 | 4–5 | An example to discuss when learning a movement |
| General strength and function | 8–12 | 5–6 | General strength guidance; adapt to your starting needs with a qualified professional |
| Getting measurably stronger | 6–8 | 7 | Depends on your plan and recorded response; not an automatic change with time |
| Heavier progressive loading | 5–6 | 7–8 | An individual prescription; completing app weeks does not establish readiness |
| Bone-targeted heavy loading (HiRIT) | 5 reps × 5 sets | Above 85% 1RM in LIFTMOR | Research dose under close supervision. Bone Builder's self-guided Peak reaches it gradually, after its unlock steps |
| Back-extensor endurance | 3–5 holds of 3–5 seconds | Low by design | Published guidance after a vertebral fracture; adapt positioning and dose with a physiotherapist |
When should you add weight, and how much?
Not before the pattern is solid, because load applied to a poor pattern is the actual risk. LIFTMOR itself opened with a lighter on-ramp so participants could master technique before the load went up. The Bone Fit™ manual makes a related point about free weights: they are preferable to machines only when the exercise has been taught with proper form and the person has enough strength to control the whole movement without compensating. In practice that means Hip Hinge Practice and Hip Hinge with Bar before a Barbell Deadlift, Chair Squat or Bodyweight Squat before a Barbell Back Squat, and often the Trap-Bar Deadlift as a friendlier first heavy hinge — the neutral grip makes it easier to keep the chest up and the spine neutral. Once that is in place:
- Review the challenge as your ability changes. Bone Fit describes progression through load, repetitions or exercise choices; adding weight is not the only option. Repeating or holding a target can be appropriate while technique, symptoms and recovery are reviewed.
- Ask a qualified professional to reassess an appropriate working load. Bone Fit™ discusses increases of 2–10% after managing 12–15 repetitions at a given load; this is general prescription guidance, not an automatic app instruction or a reason to test to failure alone.
- Review technique, symptoms, recovery, repetitions and effort before changing load. If control changes, stop that set and discuss adapting the movement or load. An app or camera score cannot verify technique — see movements to respect.
- Agree on session frequency and recovery with your clinician. LIFTMOR used two 30-minute supervised sessions a week. Bone Builder requires at least 48 hours from the end of the latest recorded strength attempt to the next start before suggesting a load increase; two comparable same-load records must also meet that recovery interval. See how the app handles progression.
- LIFTMOR assessed group bone-density changes over eight months. That observation period does not predict your result or set a deadline for repeat DXA; discuss meaningful scan comparisons and timing with your clinician.
Does supervision really matter at these loads?
Yes. LIFTMOR randomized 101 screened postmenopausal women with low bone mass: 49 to high-intensity resistance and impact training and 52 to a low-intensity home exercise control. The high-intensity group trained under close supervision in groups of up to eight per instructor. Over eight months, that group had 92% adherence and one reported minor adverse event; mean lumbar-spine BMD changed by +2.9%, compared with −1.2% in the control group. These are results for the studied groups, not a forecast for an app user. The researchers did not recommend reproducing the protocol without supervision, and Bone Fit’s summary likewise emphasizes the supervision requirement.
What if your bone density is very low, or you've had a fracture?
Then the honest answer to “how much weight” is: less, later, and with your physical therapist involved. A history of vertebral or hip fracture, a T-score of −3.0 or lower, or pain right now all place you on the Foundation track and away from loaded forward-bending and impact work — see exercise after a vertebral fracture. Too Fit to Fracture likewise advises starting at a lower intensity if you are sedentary, new to strength training or at high fracture risk. And for people who have had a vertebral fracture, the UK consensus statement summarised in the Bone Fit™ manual recommends daily back-extensor work at low intensity for endurance — exercises repeated 3–5 times and held for 3–5 seconds — rather than loaded heavy.