Strength

The evidence here is a systematic review of 16 long-term cohort studies. Doing any muscle-strengthening activity was associated with about 15% lower risk of dying from any cause and about 17% lower risk of cardiovascular disease. Crucially, the benefit peaked at just 30 to 60 minutes a week and then flattened - the curve is J-shaped, so more is not clearly better. That is two short sessions, not hours in a gym.

Momma H et al. 2022

The strength-training benefit held even after accounting for aerobic exercise - meaning it adds something walking and running don't. Muscle is a major site where your body stores and disposes of blood sugar, and keeping it strong protects your metabolism, your mobility and your independence as you age. So cardio and strength are two different jobs; doing one doesn't cover the other.

Momma H et al. 2022

The same review found muscle-strengthening activity was also linked to lower risk of total cancer (about 12% lower) and type 2 diabetes (about 17% lower). These are associations from observational data, not proof, and people who strength-train may be healthier in other ways - but the pattern across many large studies is consistent and points the same direction.

Momma H et al. 2022

The studies counted muscle-strengthening activity broadly - not just barbells. Your muscles can't tell the difference between a loaded gym machine and your own bodyweight; what matters is that they work hard enough to tire out. Sit-to-stands from a chair, push-ups against a kitchen counter, wall sits and carrying heavy shopping all qualify, with no equipment and nothing to buy.

Momma H et al. 2022

The review pooled sixteen prospective studies and found muscle-strengthening activity linked to roughly ten to seventeen per cent lower risk of death from any cause, of cardiovascular disease, of cancer overall, of diabetes and of lung cancer. It also found no association at all with several specific cancers - colon, kidney, bladder and pancreatic - and that null is reported here because a list of only the positive findings would misrepresent what the paper says. The shape matters too: for death, heart disease and cancer the curve was J-shaped, with the largest reduction at roughly thirty to sixty minutes a week and no clear further benefit beyond it. For diabetes the shape was different, with benefit continuing up to about an hour a week.

Momma H et al. 2022

No. Every study behind this figure was observational - people reported what they already did, and were followed up afterwards. People who do strength work differ from people who do not in ways that are hard to adjust away, and being well enough to exercise is itself part of the picture. What the review does add is that the association held independently of aerobic activity, which is a genuine finding rather than a restatement of "exercise is good". Read it as a consistent link, not as a demonstration that the exercise produced the difference.

The evidence gives no reason to. The largest risk reductions sat at about thirty to sixty minutes a week, and beyond roughly an hour the reviewers describe the picture as unclear - the curve for death, heart disease and cancer was J-shaped, meaning the line stopped falling and in places turned back up. That is not a reason to avoid doing more if you enjoy it, and it is certainly not a reason to think more is required. If anything the useful message runs the other way: the amount associated with most of the benefit is small enough to do at home without equipment.