What is the best supplement to increase strength?

The only strength trial a lifter can run on themselves: the log as a design, why a controlled single-person experiment outranks any testimonial, and the three rules that make it fair

What is the best supplement to increase strength is a question that every lifter can answer for themselves with a document they already keep, the training log, read as a design rather than a diary, and the page's first job is to show the design, because it outranks everything else a lifter will be told. The evidence hierarchy that the research uses places a controlled experiment above an observation and an observation above a testimonial, and the forum thread in which someone's bench went up on a product is a testimonial at the bottom; a lifter who runs a controlled single-person experiment on their own numbers has produced evidence near the top, for themselves, about themselves, which is the only population they are buying for. The design is three blocks on the same programme: a block without the product, a block with it, and a block without it again, with the top sets of the same lifts recorded in the log across all three, and the question answered by whether the middle block's line sits above the lines either side of it by more than the programme's own progress explains.

Three rules make the design fair, and they are the rules the trials use. The first is a stable programme: the same lifts, the same rep ranges and the same progression across all three blocks, because a programme change in the middle block is the thing most lifters credit a product with, and the design exists to separate the two. The second is the count of doses, which sets the blocks: creatine saturates the muscle store after around twenty-eight daily doses at 3g or a short loading period and empties over a similar count after stopping, so the middle block begins once the store is full and the third block is read for the slow return as it empties, with the washout being the half of the design most lifters never run and the half that proves the effect was the product's. The third is the comparison against the trend: a lifter's numbers rise on a good programme without any product, so the middle block is judged against the slope of the first and third rather than against zero, and a product whose block sits on the same slope as the blocks around it has done nothing the log can see.

The design has one honest limit and one honest strength. The limit is that a lifter cannot blind themselves, and knowing they are on a product can add a little to the middle block through expectation, which is why the third block matters: expectation does not wash out slowly over a count of doses and a real effect does. The strength is that the design is specific to the lifter, so that a product the meta-analyses credit with a few percent in the average lifter is tested in this one, with their stores, their plate and their training age, and the answer is theirs.

A design with three blocks and three rules, and what the meta-analyses predict the log will show for each product, creatine's line, the flat lines, caffeine's different test and the worked example, which is the next section.

What the design is predicted to show: creatine's line in the middle block and its return in the third, the flat lines of the boosters and stacks, caffeine as a same-day product the log tests differently, the worked example, and the verdict

The meta-analyses predict what the log will show before a lifter runs the design, and the prediction is the page's answer. Creatine monohydrate at 3 to 5g a day, after saturation, is predicted to lift the middle block's top sets by a few percent above the slope of the blocks either side, the figure the meta-analyses return across most people who train, with the extra repetition on the heavy set and the slightly heavier top set accumulating over the block, and the third block is predicted to show a slow return toward the first block's slope as the store empties over a similar count of doses, which is the signature of a real effect rather than an expectation. A lifter who sees that shape in their own log has the best evidence available to anyone that creatine increases their strength, and the meta-analyses say most lifters will see it, more clearly in those with low starting stores and less in heavy meat eaters.

The flat lines are the design's other prediction, and they are why the shelf does not want lifters to run it. The testosterone boosters, audited across dozens of products with almost no data and no effect on the hormone, are predicted to leave the middle block on the same slope as the blocks around it. The branched-chain amino acids, which add nothing to adequate protein, the same. The pump products, the nitric oxide boosters, the HMB in a trained lifter, the proprietary strength stacks that bundle creatine with the above at a premium, the same, with the stack's line being creatine's line at a higher price if it contains enough monohydrate and a flat line if it does not. A lifter who has run the design on one of these and seen a rise has seen the programme's slope or the expectation effect, and the third block, if they ran it, would have shown no return because there was nothing to wash out.

Caffeine is a same-day product and the log tests it differently: its effect on a session is present for the hours after a tablet and gone by the next session, so the three-block design shows nothing and the right design is within a block, the same lift on alternating sessions with and without the tablet, read for the difference on the day. The meta-analyses predict a small lift on the day at 3 to 6mg per kilogram, which the log will show on the caffeinated sessions and not on the others, and which does not accumulate; it is the best same-day supplement for strength and not a strength increase in the sense the question means, and a lifter who runs both designs has both answers.

The worked example is placed with no effect to read on the bar, which is the honest position for a mineral: {FL}, 1500mg magnesium bisglycinate stated as 300mg elemental at 80% NRV, two capsules with the evening meal, with authorised claims for normal muscle function, normal protein synthesis and electrolyte balance, which describe the mineral's role in a working muscle and are not a strength claim, and nothing the three-block design would show in a lifter who is not deficient, which this page says plainly; it is taken for a plate the survey finds a share of adults short of, batch tested for lead, mercury, arsenic and cadmium, UK made, 180 capsules for £19.99 at 22p a day. The full label breakdown is here.

The verdict: the best supplement to increase strength is the one that survives the trial a lifter runs on themselves, three blocks on the same programme, without, with and without again, read in the log against the programme's own slope. The meta-analyses predict creatine will show a few percent on the top sets in the middle block and a slow return in the third, that the boosters, the amino acids and the stacks will show a flat line, and that caffeine will show a same-day lift in a within-block design and nothing across blocks. A lifter who runs the design owns the answer, and most will find it is creatine.

What to check on the label

Questions people also ask

How can I tell if a strength supplement is actually working?

Run the trial on yourself with the log read as a design: a block without the product, a block with it and a block without it again, on the same programme with the same lifts, with the top sets recorded and the middle block judged against the slope of the blocks either side rather than against zero; a real effect appears above the slope in the middle block and returns slowly in the third as the product washes out, while expectation and a programme change do not wash out over a count of doses, which is why the third block, the one most lifters never run, is the proof.

Which supplement will show up in my training log?

The meta-analyses predict creatine monohydrate at 3 to 5g a day, after the store has saturated over around twenty-eight daily doses, will lift the top sets by a few percent above the programme's slope in the middle block, with an extra repetition on the heavy set and a slightly heavier top set accumulating, and will show a slow return in the third block as the store empties; they predict the testosterone boosters, the amino acid blends, the pump products and the strength stacks will leave the line flat, because the trials could not find their effect and the log will not either.

Does caffeine increase strength over time or just on the day?

On the day: caffeine's effect on a session is present for the hours after a tablet at 3 to 6mg per kilogram and gone by the next session, so the three-block design shows nothing and the right test is within a block, the same lift on alternating sessions with and without the tablet, read for the difference on the caffeinated days; the meta-analyses predict a small lift on those days that does not accumulate, which makes caffeine the best same-day supplement for strength and not a strength increase in the sense the question means.

Why do people think strength supplements work when they do not?

Because a lifter's numbers rise on a good programme without any product, and a product started at the same time as a programme change or a new block is credited with the programme's slope; because expectation adds a little to a block a lifter knows they are supplemented in; and because almost nobody runs the washout block, in which a real effect returns slowly over a count of doses and an expectation or a programme effect does not return at all; the three-block design on a stable programme separates the three, and the forum testimonial sits at the bottom of the evidence hierarchy for exactly this reason.

Would magnesium show up in a strength log?

Not in a lifter who is not deficient, and the page says so: magnesium has authorised claims for normal muscle function, normal protein synthesis and electrolyte balance, which describe the mineral's role in a working muscle and are not a strength claim, and the trials in non-deficient people are small and inconsistent, so the three-block design would show a flat line; the worked example is 300mg elemental at 80% NRV in two capsules with the evening meal for 22p a day, batch tested for four metals and UK made, taken for a plate the national survey finds a share of adults short of.

Sources

1. Rawson ES, Volek JS. Effects of creatine supplementation and resistance training on muscle strength and weightlifting performance. Journal of Strength and Conditioning Research 2003;17(4):822-831: creatine with resistance training produced around 8 per cent greater gains in maximal strength and around 14 per cent greater gains in repetitions at a given load than training alone. PubMed record
2. The muscle creatine saturation study: a loading dose of 20g a day for about six days or a steady 3g a day both raise muscle creatine to the same ceiling, the steady dose taking around twenty-eight daily doses to arrive, after which 3 to 5g a day maintains it and stores return to baseline over roughly a month of stopping. PubMed record
3. The caffeine and strength literature: meta-analyses report small but consistent improvements in maximal strength and power after caffeine doses in the range studied, typically 3 to 6mg per kilogram, with individual response varying. PubMed record
4. The evidence hierarchy in clinical research: systematic reviews and meta-analyses of randomised controlled trials sit above single randomised trials, which sit above pilot and uncontrolled studies, which sit above animal and cell work, and a claim is proven in proportion to the highest level it reaches and the number and size of studies at that level. PubMed record

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