Strength Training for Healthy Aging: What Your Metrics Can and Cannot Show

Strength is what lets you climb the stairs without the handrail, carry the shopping in one trip and get out of a low chair easily. Muscle-strengthening work helps you keep those abilities as you age, yet a wearable sees only part of it. This guide covers how much to do, how to progress, what research associates with it, and what My Bio Age can and cannot tell you.

How much and how often

The CDC's guidelines for adults recommend muscle-strengthening activity on at least two days a week, working all the major muscle groups: legs, hips, back, abdomen, chest, shoulders and arms. That comes on top of 150 minutes a week of moderate aerobic activity.

It doesn't have to mean a gym. The NHS's strength exercises include sit-to-stands, mini-squats, calf raises and wall press-ups, mostly done holding a chair or a wall for support.

The National Institute on Aging explains why this matters later in life. Being active makes everyday jobs such as housework or getting out of bed easier, which helps people stay independent. It may also help slow sarcopenia, the gradual loss of muscle and strength that comes with age, and staying strong and mobile can make a fall less likely.

What the evidence suggests

A 2022 meta-analysis by Momma and colleagues pooled 16 prospective cohort studies of adults. Across them, people who reported muscle-strengthening activity had roughly a 10–17% lower risk of several outcomes: death from any cause, cardiovascular disease, cancer overall, diabetes and lung cancer. For death, cardiovascular disease and cancer, the largest reductions appeared at roughly 30–60 minutes a week, and people who did both strength and aerobic activity had a lower risk of death than those who did neither.

Keep these findings in proportion. Cohort studies show associations, not proof that lifting caused the difference, and several of the curves were J-shaped: the benefit didn't keep growing beyond about an hour a week, and the authors called the effect of larger volumes unclear. A couple of modest sessions a week appears worthwhile; long ones aren't required.

Strength work can also build lean mass later in life. A 2011 meta-analysis by Peterson and colleagues pooled 49 resistance training studies in adults aged 50 and over. After an average of about 20 weeks, participants gained roughly 1.1 kg of lean body mass. Higher-volume programmes produced larger gains, and older participants tended to gain less.

Progress sensibly

Muscles adapt when they are asked to do a little more over time, an idea known as progressive overload. The American College of Sports Medicine's position stand on resistance training suggests that beginners use loads they can lift for about 8–12 repetitions, two or three days a week, and add roughly 2–10% once they can manage one or two repetitions beyond their target. It also stresses fitting any plan to your goals, capacity and training history.

• Start light, technique first. Learn each movement slowly, with a weight you can control, before adding more.
• Change one thing at a time. Add a repetition, a set or a little weight, not all three in the same week.
• Get guidance if you need it. With a heart condition, diabetes, high blood pressure, joint problems or an injury, ask a doctor or physiotherapist which exercises suit you. The NHLBI also suggests talking with your doctor about symptoms such as chest pain or dizziness during activity.

What My Bio Age sees, and what it misses

My Bio Age doesn't log sets, repetitions or weights. It works from Apple Health data, so a strength session shows up only indirectly:

• Active energy. The calories your watch estimates for a session add to that day's active energy. That is an energy estimate, not a record of what you lifted, so a short, heavy session can register as fairly little.
• Training Load. Training Load compares your average daily active energy over the last 7 days with the last 28, so it shares that blind spot. Our guide to the acute:chronic ratio explains the zones.
• Recovery and HRV. Recovery (Recovery Capacity) combines heart-rate recovery with resting heart rate and HRV trends, and includes its overnight part only when sleep data is present. A run of hard weeks may show as a dip, but so can illness or a run of poor nights, if they shift your resting heart rate or HRV. It needs at least one heart-rate recovery reading from the last 14 days, and not every session produces one.
• Lean body mass, if you log it. If a smart scale saves your body weight and lean body mass to Apple Health, My Bio Age uses their ratio as optional context that adjusts how much emphasis heart-rate inputs, such as resting heart rate and HRV, receive in the weekly MyBioAge Index™. It isn't a muscle score, and lean mass usually changes slowly. See body composition and lean mass in Apple Health.

None of these can see the load on the bar, your technique, or whether everyday tasks feel easier. If the stairs or the shopping become easier, that progress is real even if your Index stays flat.

My Bio Age 1.0.23, now in development, will add an optional setting, “Estimate from workout cooldowns”, which will be off by default. With it on, a strength session followed by a separately logged Cooldown workout can provide a heart-rate recovery estimate for your Recovery score. Mind-and-body, flexibility and “Other” workouts don't count as exercise for this, so log lifting as a strength workout. Read how cooldown estimates work before relying on them.

A simple weekly plan

1. Two or three strength sessions, covering all the major muscle groups across the week.
2. A day's rest for each muscle group. The National Institute on Aging advises leaving a day between sessions that work the same muscles. Aerobic activity such as brisk walks or cycling can go on any day.
3. A log outside the app. Note exercises, weights and repetitions, plus one everyday task you would like to find easier.
4. A weekly review. Look at your log alongside Training Load, Recovery and how you feel. If load is climbing and Recovery has drifted down for several days, hold your weights steady for a week. Our guide to balancing training load and recovery has a fuller routine.

Where My Bio Age fits

Strength training is one of the habits most worth keeping as you age, and one of the hardest for a wearable to measure. My Bio Age shows how your activity and recovery shift day to day in Training Load and Recovery, and across complete weeks in the MyBioAge Index™, while your own log records the lifting. Read more about lowering your biological age score without chasing the number and what functional age means.

Keep your lifting log and use My Bio Age for the wider activity and recovery picture: download My Bio Age free on the App Store. The iPhone app is completely free, with no in-app purchases, subscription or account required. Your Apple Health data is processed privately on your iPhone, so reviewing your weekly trends does not require uploading it.

My Bio Age offers general wellness information, not medical advice, and cannot tell you whether an exercise is safe for you. If you have pain that changes how you move, chest pain, dizziness or unusual breathlessness, stop and speak to a doctor or other qualified professional. The NHS advises calling emergency services for sudden chest pain that does not go away.