Two sessions a week, covering the major muscle groups, is the whole starting prescription for strength training in your 40s and 50s. That is the NHS guideline for adults, and the trial evidence suggests a modest amount of work does most of the job. What changes with age is how long the tissue takes to catch up.
The short version
- The NHS asks for strengthening work on at least two days a week.
- A low training volume delivers most of the function and muscle-size benefit.
- Strength and walking speed improve more reliably than muscle mass does.
- Tendon adapts slower than muscle, so add load across months.
- Heavier is not automatically better, particularly with an arthritic knee.
What actually changes after 40
Three tissues change on three different clocks, and confusing them is where most midlife training goes wrong.
Muscle is the one everybody knows about. The age-related loss of muscle mass alongside strength or physical function has a name, sarcopenia, and it is described in the endocrinology literature as a syndrome of ageing rather than a disease you catch. It does not arrive at 65 with a diagnosis attached. It accumulates quietly from midlife, faster in people who sit more.
Bone is the second. The NHS is blunt about it: losing bone is a normal part of ageing, and women lose bone rapidly in the first few years after the menopause. Resistance training does move bone density, and by less than the fitness industry implies. A systematic review in Osteoporosis International pooled 17 studies of dynamic resistance training in postmenopausal women, all running at least six months. Standardised mean differences came out at 0.54 at the lumbar spine, 0.22 at the femoral neck and 0.48 at the total hip. The authors called those effects significant but only low to moderate, and said their sub-analyses did not allow meaningful training recommendations to be derived. So lift, because the direction of travel is right and the rest of the benefits are real, but do not treat a set of dumbbells as a replacement for a bone density scan, or for medication where your GP thinks it is indicated.
Tendon is the third, and the one almost nobody plans for. A review of leg extensor mechanics found consistent reductions in calf and thigh muscle strength with ageing, accompanied by similar reductions in tendon stiffness. The change sits in the material the tendon is made of rather than in its size.
In my years of practice, the person who ended up in the treatment room was rarely someone who had done nothing. It was more often someone who had started well, trained the muscle hard for six weeks, and got caught out by a tendon that had not kept pace.
Why the tendon is the slow part
Muscle responds inside a few weeks. Some of that early gain is not new muscle at all, it is your nervous system learning to recruit what you already have. That is why the first month of any programme feels so encouraging.
Tendon works on a longer clock. The same review found that human tendons keep their mechanosensitivity with age, with older adults showing changes of similar magnitude to younger adults over 12 to 14 weeks of training. The catch is the dose. The authors concluded that loading needs to sit high, in the region of 80 to 90 per cent of maximum voluntary contraction, repeated for up to three or four months, to shift the age-related changes.
Read that as a timescale, not as an instruction to load up on day one. You do not start at 85 per cent of anything. You spend the first couple of months earning the right to train there, and you accept that the Achilles, the patellar tendon and the elbow are still catching up while the thigh is already showing off.
How much you actually need, and what improves first
Less than most people assume. A network meta-analysis in Sports Medicine pooled 151 randomised trials covering 6,306 older adults and compared low, moderate and high training volumes. Low volume came out as the most effective for the timed up and go test, the six-minute walk, lean body mass and muscle size. Moderate and high volumes were better for lower-limb strength, and only high volume improved fast walking speed.
Two caveats matter before you take that to the gym. Those participants were 60 and over, so the finding tells you the shape of the response rather than an exact dose for a 45-year-old. And the effects were clearest in healthy older adults, with the evidence thinner in people who were already physically impaired.
The practical read is that the first two sessions a week buy you most of what you are after. The case for training more than that is strength itself, and that case only becomes relevant once the habit is fixed.
A meta-analysis of 14 randomised trials in 561 older adults with sarcopenia found that resistance training improved handgrip strength, knee extension strength, gait speed and the timed up and go test. Body fat mass came down. What did not reach statistical significance was appendicular skeletal muscle mass, total skeletal muscle mass or leg lean mass.
So a group of people got stronger and moved better without the scans showing much more muscle. That is worth knowing before you judge three months of work by what the mirror says. Function improves ahead of size, and function is the thing that has you carrying shopping up the stairs at 70.
Training when something already hurts
This is where the assumption that harder is better falls over. The START trial, published in JAMA, randomised 377 adults aged 50 and over with knee osteoarthritis to high-intensity strength training, low-intensity strength training or an attention control, then followed them for 18 months. High-intensity training did not reduce knee pain more than the low-intensity group or the control group, and it did not reduce the compressive force through the knee during walking. It did generate more non-serious adverse events than either comparison.
That is one trial in one condition, and it does not make strength work pointless for a sore knee. It does mean the dial people reach for first, load, is not the dial doing the most work. Starting light and staying consistent beats starting heavy and stopping in week three.
The same logic applies to backs. We went through the specifics in what to keep and what to drop when your back hurts, and for a knee that has been grumbling for months, an assessment of the knee itself will tell you more than another set of leg extensions.
When to speak to a GP first
The NHS advice is to speak to your GP before starting if you have not exercised for some time, or if you have medical conditions or concerns. Take that literally at this age.
Stop and get medical advice the same day for chest tightness, unusual breathlessness or light-headedness during effort. The same goes for new numbness, pins and needles or weakness in an arm or leg, a joint that swells quickly or will not take your weight, or pain that wakes you at night and is not eased by changing position, particularly alongside unexplained weight loss, fever or night sweats. Loss of bladder or bowel control, or numbness around the saddle area, is an emergency and needs A&E rather than an appointment.
Where to actually start
Two sessions a week, around 40 minutes each, six movements. One squat or sit-to-stand pattern, one hinge, one push, one pull, one carry, one calf raise. Between them those cover the muscle groups the NHS guideline lists, which is legs, hips, back, abdomen, chest, shoulders and arms.
Two or three sets of eight to twelve repetitions on each. Pick a weight you could have managed two or three more reps with, then leave it alone for a fortnight before you add anything. Add small amounts. Nobody in their 50s needs to test a one-rep maximum to find out whether a programme is working. If the last repetition of a set is a genuine struggle every single session, the weight is too high for where you are, and the tendon will let you know about it before the muscle does.
Give it three months before you judge it, because that is roughly how long the tendon needs. Expect the first six weeks to feel easy and the seventh to feel like something is complaining. That is usually a signal to hold the load steady for a week or two rather than to stop.
If you would rather not guess at it, our osteopaths run exercise rehabilitation alongside hands-on treatment, and the clinic team sees around 100 patients a week across Luton and the surrounding towns, a fair number of them people restarting training in midlife. An initial assessment is £75 and covers a history, a movement assessment and a plan you can follow at home or in a gym.
If this sounds like what you're dealing with, an assessment is the next step. Book online here.