Tip · Exercise

Strength training 3× per week

Q: Are two training sessions per week enough, or does it have to be three?

For bone strength, the DVO S3 guideline calls for at least twice per week on an annual average; for training focused on fall prevention, it cites around three sessions. The meta-regression across 67 studies shows that a higher frequency mainly increases strength, while the effect on muscle mass is compatible with a negligible difference. Two sessions are therefore no half measure. The third mainly distributes the weekly volume.

Q: How much weight does it have to be?

For capable persons, the DVO guideline cites a range of 60 to 90 % of the one-repetition maximum with varying stimulus magnitude so that the bone structure does not become desensitized. LIFTMOR trained above 85 % of the one-repetition maximum in 5 sets of 5 repetitions. At the same time, the same guideline states with recommendation grade A that training should not be done at a high degree of exhaustion. Heavy here therefore does not mean to muscle failure.

Q: Is strength training dangerous with osteoporosis?

The LIFTMOR study tested exactly that: 101 postmenopausal women with osteopenia or osteoporosis, eight months of training above 85 % of the one-repetition maximum, a single adverse event, and bone density at the lumbar spine rose instead of falling. What matters is that the training was supervised throughout. With existing vertebral fractures, different rules apply: there, according to the DVO guideline, jumps and high axial compression loads are contraindicated.

Q: Can I still build muscle at over 70?

Fiatarone’s study was conducted in nursing home residents with a mean age of 87.1 years and found a strength increase of 113 % after ten weeks. The muscle cross-sectional area of the thigh, however, rose by only 2.7 % and missed significance. The rapid gain is therefore initially neural. Mass takes longer.

Q: Does strength training lower my blood sugar?

Yes, but less than endurance or interval training. In a network meta-analysis in older people with type 2 diabetes, the estimated HbA1c reduction from strength training was 0.29 percentage points, from HIIT 0.95 and from combined training 0.59. Anyone whose main goal is blood sugar is therefore better off combining. A second network meta-analysis in 633 overweight people with type 2 diabetes found the optimum at three times per week and 45 minutes per session.

Q: Do I have to train to muscle failure?

For healthy, capable people there is no clear guideline on this, and the meta-regression mainly shows that weekly volume counts. For everyone with reduced bone strength, by contrast, the answer is clear. The DVO guideline states with recommendation grade A and evidence level 1a that training should not be done at a high degree of exhaustion, and in the osteoporotic range, exhaustion to momentary muscle failure should be avoided.

The best-supported single measure in this database: muscle mass, bone density, metabolism, mortality.

Strength training has the broadest data base in this database: muscle strength, bone density, blood sugar and mortality have all been studied. The tip is here because the core holds up — and because the useful information is not that you should train, but how often, how heavy and how close to muscle failure.

In short

It works, and across an unusually wide age range. In nursing home residents with a mean age of 87.1 years, muscle strength rose by 113 ± 8 % in ten weeks, compared with 3 ± 9 % without training. In postmenopausal women with osteopenia or osteoporosis, bone density at the lumbar spine rose by 2.9 ± 2.8 % in eight months instead of falling by 1.2 ± 2.8 % as in the control group. For mortality there is an association from 16 cohort studies: 10 to 17 % lower risk — observed, not measured in an intervention study. The optimum of this curve lies at around 30 to 60 minutes of muscle-strengthening activity per week and is therefore lower than training culture suggests.

What is behind it

Mechanical load deforms muscle and bone and triggers two separate adaptations. In muscle, radial fiber hypertrophy arises via additional myofibrils, and longitudinal growth via additional sarcomeres. Weekly sets, volume load, rest between sets and proximity to muscle failure measurably influence this, whereas the choice of exercise is flexible.

In bone, the stimulus is not muscle mass but the deformation itself. The S3 guideline of the German umbrella association for osteology (DVO) assigns high importance to the rate of deformation in addition to the magnitude of the stimulus, and states that the unloading phase is just as important as the loading phase.

How much, how often, how heavy

The volume question is answered by the largest available meta-regression, 67 studies with 2,058 participants: the posterior probability that more weekly sets increase both hypertrophy and strength is 100 %. Both models, however, show diminishing returns, much more pronounced for strength.

On training frequency, the two goals diverge. For strength, the posterior probability is also 100 %: more sessions, more strength. For hypertrophy it is lower and compatible with a negligible effect. Going from two to three sessions therefore mainly distributes weekly volume. For bone strength, the DVO guideline calls for at least twice per week on an annual average (recommendation grade A, evidence level 1a) and cites around three sessions for training focused on fall prevention. Two sessions are therefore no half measure.

The metabolic part is the weakest

Strength training lowers long-term blood sugar, but at the lower end of all training forms tested. In a network meta-analysis in older people with type 2 diabetes, the estimated HbA1c reduction was −0.29 % (95 % CrI −0.51 to −0.08) — behind HIIT at −0.95 %, combined training at −0.59 % and aerobic training at −0.46 %.

What is well supported

The two intervention studies carry the most weight. In 100 frail nursing home residents, muscle strength rose by 113 ± 8 % in ten weeks compared with 3 ± 9 % (p < 0.001), gait speed by 11.8 ± 3.8 % and stair-climbing power by 28.4 ± 6.6 %. In the LIFTMOR study with 101 postmenopausal women, bone density at the lumbar spine rose by 2.9 ± 2.8 % compared with −1.2 ± 2.8 % (p < 0.001) and remained stable at the femoral neck (0.3 ± 2.6 % compared with −1.9 ± 2.6 %). For bone strength, dynamic strength training is at the highest level in the DVO S3 guideline: recommendation grade A, evidence level 1a, consensus strength 100 %.

What the studies show

Fiatarone 1994: the intervention with the largest effect

Randomized, placebo-controlled trial with four arms — progressive strength training, nutritional supplement, both, neither. 100 frail nursing home residents, mean age 87.1 ± 0.6 years with a range of 72 to 98, ten weeks, 94 % study completion, training of the hip and knee extensors on three days per week. Strength rose by 113 ± 8 %, while thigh muscle area rose by only 2.7 ± 1.8 % and missed significance (p = 0.11). The nutritional supplement alone had no effect on any primary outcome.

LIFTMOR 2018: the counter-test to a common warning

High-intensity strength training was long considered risky in osteoporosis. 101 postmenopausal women with a T-score below −1.0, aged 65 ± 5 years, were randomized: 49 trained under supervision for eight months, twice a week for 30 minutes, with 5 sets of 5 repetitions above 85 % of the one-repetition maximum plus impact training; 52 completed a low-intensity home program. Bone density rose instead of falling, all functional tests came out in favor of the training group with p < 0.001, and compliance was 92 ± 11 %. A single adverse event occurred, a mild back spasm with two missed sessions out of 70.

Momma 2022: the observational basis for mortality

Systematic review and meta-analysis of prospective cohort studies, 16 included studies. Muscle-strengthening activity, independent of aerobic activity, was associated with a 10 to 17 % lower risk of all-cause mortality, cardiovascular disease, total cancer, diabetes and lung cancer. No association was found for colon, kidney, bladder and pancreatic cancer.

Where the data stop

The mortality part is entirely observational. There is no randomized trial that sets strength training against no strength training and measures all-cause mortality as the primary end point. Added to this is the shape of the curve: above 30 to 60 minutes per week, the association not only flattens out, it reverses in the pooled curve. The authors explicitly describe the effect of higher volume as unclear. Whether this is a biological limit or an artifact of self-report and residual confounding is open. The training data themselves come predominantly from young men: in the large meta-regression, 79.1 % of the 2,058 participants were male, with a mean age of 25.16 ± 5.22 years.

How to do it

For capable persons around menopause, the DVO guideline describes periodized strength training, ideally of all major muscle groups, with 10 to 13 exercises, variable stimulus intensity of 60 to 90 % of the one-repetition maximum and variable movement speed, as single-set or multiple-set training, with or without machines. The stimulus magnitude should vary to avoid desensitization and overloading of the bone structure. Beginners and people with severe orthopedic limitations should train on guided machines where possible, advanced trainees increasingly with free weights. And progression should be slow: overloading of tendons can only be avoided through a gradual increase in load.

Safety

Regardless of risk profile, the DVO S3 guideline names no fundamental contraindication to physical training, as long as training content and load dosage are chosen appropriately; cardiovascular diseases are more of an indication than a contraindication. There are four concrete limits. Exhaustion: strength training should not be performed at a high degree of exhaustion (recommendation grade A, evidence level 1a), and in the osteoporotic range, training to momentary muscle failure should be avoided. Flexion of the spine under load should be avoided in principle — without load, flexion and extension are explicitly unproblematic. Impact loading: with vertebral fractures, jumps and intensity-focused axial strength training with high loads are contraindicated; with osteoporosis without fracture, high-intensity jump forms such as drop jumps should be omitted; with joint replacements, the same applies to impact and rotational loads. And breathing technique: attention must be drawn to avoiding the Valsalva maneuver. The guideline does not name the deadlift as contraindicated anywhere; in substance, it falls under high axial compression loading. This is information, not a treatment recommendation.

BK-Score Well supported

Human evidence		9
Mechanism		8
Safety data		9
Hype gap		8
Track record of use		10

Strength training is the best-supported single measure in this entire database: meta-analyses show effects on muscle mass, bone density and metabolism. For mortality it is an association from cohort studies, not a measured effect, and the dose-response curve is J-shaped with an optimum at 30 to 60 minutes per week. The deduction concerns the phrase “nothing is as anti-aging” – a comparison that no study has made in that way.

The score rates the state of knowledge, not the effect. “Safety data 9” means well studied – not harmless.
Subjective assessment by Biohacking Kompakt based on published scoring rules – not a scientific rating and not a medical recommendation. Rules and all ratings (German)

Frequently asked questions about strength training 3× per week

Are two training sessions per week enough, or does it have to be three?