Strength Training After 40: The Supplement Questions Worth Asking

If you started lifting in your 40s, or came back to it after years away, you've probably noticed how fast the supplement conversation shows up. Someone at the gym swears by their pre-workout. An ad promises "anabolic support." A podcast recommends five things you've never heard of. The volume of recommendations tends to run in the opposite direction from the evidence behind them.

You don't need to evaluate every product on the shelf. A handful of questions, asked in the right order, sorts out most of them. This post walks through those questions and the research behind each one. Some of the answers point toward a supplement. More of them point somewhere else, and a couple point toward things worth avoiding entirely.

First, why strength training is worth doing at all

The case for lifting after 40 doesn't depend on anything you can buy.

The World Health Organization's 2020 guidelines on physical activity, published by Bull and colleagues in the British Journal of Sports Medicine, volume 54, pages 1451 to 1462, recommend that adults do muscle-strengthening activities at moderate or greater intensity, involving all major muscle groups, on two or more days a week. The WHO rated this a strong recommendation supported by moderate-certainty evidence.

For older adults, the guidelines go a step further. As part of their weekly activity, older adults should do varied multicomponent physical activity that emphasizes functional balance and strength training, at moderate or greater intensity, on three or more days a week, to enhance functional capacity and prevent falls. The review behind the guidelines found high-certainty evidence that balance and functional exercises reduce the rate of falls.

A 2022 systematic review and meta-analysis by Momma and colleagues, also in the British Journal of Sports Medicine, reported that muscle-strengthening activities are associated with lower risk and mortality across major non-communicable diseases.

One more detail from the WHO work is worth knowing. The review found no evidence supporting a dose-response association with higher volumes of muscle-strengthening activity for health outcomes. In other words, the target is two or more sessions a week done properly, not living in the gym.

Question 1: Is the training itself actually in place?

This comes first because it determines whether any supplement has something to work with.

Supplements that help with strength training work on the adaptation to training, not in place of it. We went through the evidence on this in detail in our post on muscle loss in midlife. The short version is that in research on older adults, resistance training consistently does the heavy lifting, and nutrition makes it work somewhat better. Where the two have been compared directly, adding nutritional support to a training program often produced little or no extra benefit over the training program alone.

So before anything else, check the basics against the WHO baseline. Are you training all the major muscle groups, legs, hips, back, chest, core, shoulders, and arms, at least twice a week? Is the effort genuinely moderate or harder? The WHO describes moderate intensity, on a scale relative to your own capacity, as usually a 5 or above out of 10. Are you gradually asking your muscles to do a bit more over time, whether that's more weight, more reps, or harder variations?

If the answer to any of those is no, fixing it is the highest-return change available to you, and nothing in a tub substitutes for it.

Question 2: Is your protein handled before anything else?

Protein is the one nutritional input with a direct, well-established role in building and maintaining muscle, so it belongs ahead of any supplement in the queue.

We've covered protein after 40 separately, so this is just the part that matters most for training. The total amount matters, but so does how it's spread across the day. The PROT-AGE Study Group, in its 2013 position paper by Bauer and colleagues in the Journal of the American Medical Directors Association, described a higher per-meal threshold for older adults, roughly 25 to 30 grams of protein per meal containing about 2.5 to 2.8 grams of leucine. That recommendation was written for people over 65, but the underlying point, that a meal needs enough high-quality protein to register as an anabolic signal, is a useful habit to build earlier.

If you use a protein powder, think of it as a way to make a low-protein meal count, usually breakfast, rather than as a performance product. And source matters here. For the specific job of clearing a per-meal leucine threshold, a whey-dominant protein does it more efficiently than a collagen-dominant one. Our own blend leans toward collagen, and we'd rather tell you that than let you assume it's optimized for this particular purpose.

Question 3: What exactly was measured, in whom, and how big was the effect?

Once training and protein are in place, this is the question that filters the rest of the shelf. It has three parts.

What was measured. Strength, muscle size, physical function, and lab markers are four different things. A supplement can move one without moving the others. Plenty of products cite studies showing a change in a blood marker or a signaling pathway, which is not the same as showing you'll lift more or move better.

In whom. A great deal of sports supplement research is done in young, trained men. Results in that group don't automatically carry over to a 45-year-old woman who started lifting last year, or to a 60-year-old man returning after a long break.

How big. A statistically significant result can still be small. The confidence interval tells you how precise the estimate is, and whether it plausibly includes no effect at all.

Creatine is a useful worked example, because it's the supplement most people in this position ask about, and because the evidence in older adults is genuinely good but narrower than the marketing suggests. A systematic review and three-level meta-analysis of resistance training plus creatine in older adults found a significant improvement in muscle strength compared with training alone, with a Hedges' g of 0.31, a 95 percent confidence interval of 0.18 to 0.45, and moderate certainty of evidence. The same analysis found no statistically significant effect on muscle mass, with a confidence interval of negative 0.09 to 0.78, or on physical function, with a confidence interval of negative 0.08 to 1.03.

Run that through the three questions. Measured: strength, yes; mass and function, not significantly. In whom: older adults, which is relevant. How big: small, but with a confidence interval that stays clear of zero. That makes creatine a reasonable addition if strength is your goal and you set realistic expectations. We sell creatine monohydrate, and that's the honest version of the case for it.

Question 4: Could it actually work against your training?

This is the question almost nobody asks, and it's the one with the most surprising answer.

Exercise produces reactive oxygen species, molecules often described simply as oxidative stress. The intuitive move is to neutralize them with antioxidant supplements. But researchers increasingly view some of these molecules as signals that help tell muscle to adapt. Blocking the signal could, in principle, blunt the response.

A randomized placebo-controlled trial by Bjørnsen and colleagues, published in the Scandinavian Journal of Medicine and Science in Sports in 2016, volume 26, pages 755 to 763, tested this directly. Thirty-four men aged 60 to 81 followed the same strength training program, three sessions a week for 12 weeks. Half took 500 milligrams of vitamin C and 117.5 milligrams of vitamin E before and after training, and half took a placebo.

The placebo group gained more. Rectus femoris thickness, a front thigh muscle, increased by 3.4 millimetres in the placebo group compared with 1.9 millimetres in the supplement group, and leg lean mass rose by around 5 percent versus around 2 percent. The paper's title states the conclusion: vitamin C and E supplementation blunts increases in total lean body mass in elderly men after strength training. Not every measure differed between groups, but the ones that did all pointed the same way. The authors suggested that high-dose antioxidants may suppress the signaling that activates hypertrophy pathways.

A follow-up analysis from the same research group, published by Stunes and colleagues in the European Journal of Applied Physiology in 2017, is titled plainly: high doses of vitamin C plus E reduce strength training-induced improvements in areal bone mineral density in elderly men.

The evidence isn't one-sided, and it's worth saying so. A 2014 study by Paulsen and colleagues in the Journal of Physiology found that vitamin C and E supplementation altered protein signaling after a strength training session, but not muscle growth over 10 weeks of training. An earlier study by Bobeuf and colleagues in healthy older adults reported a significant gain in lean mass only when resistance training was combined with vitamin C and E. A 2020 review of this literature in the International Journal of Environmental Research and Public Health also cautioned that findings in older adults may not represent athletic populations.

So this isn't settled. What can be said is that there's no good evidence that high-dose vitamin C and E supplements help strength training, and there's a well-designed trial suggesting they can blunt gains in older men. These studies tested high-dose supplements, not antioxidant-rich food, which is a separate question. If you're taking high-dose C and E specifically to help your training, the research doesn't support it.

Question 5: Is it doing a job your food already does?

Branched-chain amino acids, sold as BCAAs, are one of the most common strength training supplements, and they're a clean example of this question.

The three branched-chain amino acids are leucine, valine, and isoleucine. A multimillion-dollar supplement category has grown around the idea that taking them on their own stimulates muscle protein synthesis. Robert Wolfe of the University of Arkansas for Medical Sciences examined that claim in a 2017 review in the Journal of the International Society of Sports Nutrition, volume 14, article 30, titled "Branched-chain amino acids and muscle protein synthesis in humans: myth or reality?"

His reasoning is straightforward once laid out. Building new muscle protein requires all the essential amino acids, not just three of them. If you take only BCAAs, the other essential amino acids have to come from breaking down existing muscle protein. That puts a hard ceiling on how much new protein BCAAs alone could drive, and Wolfe notes that even his theoretical estimate of that ceiling is an overestimate. His conclusion: the claim that consumption of dietary BCAAs stimulates muscle protein synthesis or produces an anabolic response in human subjects is unwarranted.

Complete protein, from food or a quality powder, already contains the branched-chain amino acids along with every other essential amino acid your muscle needs. If your protein intake is in good shape, a standalone BCAA product is paying for a subset of something you're already getting in full.

The broader habit is worth keeping. Before buying an isolated ingredient, check whether your diet already supplies it in a more complete form. For a lot of products, it does.

Question 6: Is it only what the label says it is?

This is the question that matters most for the strength training category specifically, because the documented problems are concentrated here.

A 2018 study by Tucker and colleagues at the California Department of Public Health, published in JAMA Network Open, volume 1, issue 6, analyzed the FDA's Tainted Products Marketed as Dietary Supplements database from 2007 through 2016. It found 776 supplements containing unapproved pharmaceutical ingredients, from 146 companies. The three most affected categories were sexual enhancement at 45.5 percent, weight loss at 40.9 percent, and muscle building at 11.9 percent.

The muscle building findings are specific. Of 92 adulterated muscle building products, 82, or 89.1 percent, contained synthetic steroids or steroid-like ingredients. Seventy-three contained undeclared anabolic steroids or steroid-like substances. Across all 776 products, 157, or 20.2 percent, contained more than one unapproved ingredient. The authors wrote that adulteration with active pharmaceutical ingredients does not happen by accident.

One more detail cuts against a common reassurance. Twenty-eight products were named in more than one warning issued more than six months apart, and of those, 67.9 percent contained new unapproved ingredients in the later warnings. A product being pulled and brought back doesn't mean the problem was fixed.

An accompanying editorial by Pieter Cohen in the same issue was titled "The FDA and Adulterated Supplements: Dereliction of Duty," which gives a sense of how the research community read these findings.

For practical purposes, the pattern suggests where to be most skeptical: products marketed with aggressive muscle building language, claims of anabolic, steroid-like, or hormonal effects, and proprietary blends that don't disclose amounts. Single-ingredient products with clear documentation are easier to evaluate. For people who need extra assurance, such as competitive athletes subject to drug testing, certification programs such as NSF Certified for Sport exist specifically to screen products for banned substances.

It's worth being precise about our own testing here. Our lab reports cover things like potency, microbial safety, and, for some products, heavy metals. They are not banned-substance screens, and we're not going to suggest they are.

What that leaves

Worked through in order, the questions produce a short and fairly unglamorous list.

Training comes first, at the WHO baseline of two or more sessions a week covering all major muscle groups at a genuine effort level, with balance and functional work added as you get older.

Protein comes second, with attention to how it's distributed across meals, and a leucine-dense source if clearing that per-meal threshold is your goal.

Creatine monohydrate is the one addition with a consistent, if modest, strength benefit alongside training in older adults, supported by moderate-certainty evidence.

Standalone BCAAs add little if your protein intake is adequate. High-dose vitamin C and E aren't supported for training and may blunt gains. And products sold with steroid-like or hormonal muscle building claims are the part of the market where adulteration is most documented.

We don't sell a standalone BCAA product or a high-dose vitamin C and E supplement, so we have no stake in those two answers either way.

The honest summary

Strength training after 40 is well supported on its own terms. The WHO recommends muscle-strengthening activity on two or more days a week as a strong recommendation, adds multicomponent balance and strength work for older adults to help prevent falls, and found no evidence that higher training volumes add further health benefit.

Supplements sit downstream of that. Asking what was measured, in whom, and how big the effect was turns creatine into a reasonable, modest option for strength rather than a transformation. Asking whether something could interfere turns up a randomized trial in which high-dose vitamin C and E blunted muscle gains in older men, alongside other studies that found smaller or no effects. Asking whether your food already does the job makes standalone BCAAs largely redundant, per Wolfe's 2017 review. And asking whether a product is only what its label says points straight at the muscle building category, where 89.1 percent of the adulterated products in the FDA's database contained steroids or steroid-like ingredients.

That's fewer products than most people expect to end up with. It's also a list you can actually defend, which is more than can be said for most of what's on the shelf.