Some drugs have relatively long half-lives, this being a measure of how quickly the drug leaves the system.
When such a drug is being used, then the amount in the system at any given time is not only that resulting from the dose just taken, but also a further amount that is remaining from previous doses.
So, using a steroid cycle as an example, suppose someone is dosing 100 mg/day of a steroid which has a half-life of one week, and over the long term this is giving him the levels he wants.
Once well into his cycle, after any given injection he will have in his system not only the 100 mg that he just injected, but another 700 mg (one half-life’s worth) remaining from previous injections.
So clearly, if on Day 1 all he does is inject 100 mg, he won’t have nearly the levels that his cycle, over time, will eventually produce. He would need to inject 800 mg to be in a comparable place.
Frontloading is the practice where a calculated larger injection amount is used on Day 1 to promptly bring levels to the same value that they would eventually stabilize at.
The amount to use is the amount that is on average taken in one half-life of the drug, plus the injection amount that will ordinarily be used.
So for another example, let’s say someone is planning on using 600 mg/week of testosterone enanthate, taken as 200 mg three times per week.
If figuring the half-life at 5 days, then on average the amount taken per half-life (per 5 days) is 5/7 of the 600 mg. That works out to an average of 429 mg taken per 5 days.
So the frontload amount is that amount, plus the usual ongoing amount of 200 mg.
If being highly exact this would work out as 629 mg, but as 600 mg is a more convenient figure, this would be more than close enough. There’s no problem in rounding the number a little.
So on Day 1 the injection would be 600 mg. This would not produce unusually high levels, but instead would promptly get levels to where they need to be.
If not frontloading but just doing the 200 mg 3x/week schedule, even at the end of two weeks levels would still be building. Only by the 3 week point (approximately) would they be nearly to their steady-state value — the value where they will or would eventually stabilize.
Equipose Boldenone undecanoate liquid has a particularly long half-life and so if there is no frontload, it takes even longer for levels to build. This is why many say that it takes 6 weeks, or some similar figure, for it to anything.
Actually the boldenone is capable of contributing well by the end of the first week, if the levels are there, but in the situations being referred to levels are not there due to lack of frontload.