Steroid Esters, Half-lives, and Blood Concentrations

We're all pretty familiar with varioussteroid esters and there associated half lives. After all this isnewbie stuff, right? Well, maybe, but I was a little enlightenedwhen I took the time to actually plot out a typical cycle.


To keep everything as simple aspossible lets look at a typical first cycle:


Testosterone Cypionate: 500mg/week(divided two 250mg injections weekly Mon, Thr) for 8-weeks


Most are aware the cypionate ester hasa half life of approximately 12 days. What this means is that after12 days the amount of the dose remaining in the body is reduce byfifty percent. So looking at just the first 250mg injection:


Day 1: 250mg
Day 12: 125mg
Day 24: 63mg
Day 36: 31mg
Day 48: 16mg
Day 60: 8mg
Day 72: 4mg
Day 90: 2mg
Day 102: 1mg


This first important point is that theamounts listed above are the quantities of testosterone cypionatestill in the oil depot NOT the amount of testosterone in theblood. There is a big difference as we'll soon see.


Sticking with just the first 250mginjection, on day one approximately 1/12 of half the injected amountis converted to actual testosterone and released into the blood(250mg / 2 = 125mg / 12 = 10.4mg). Note: For simplicity we'll notfactor in the weight of the ester and assume the 250mg of test-c willultimately release 250mg of testosterone. This same amount isreleased for each of the next 11 days from this dose.


Now, still looking only at the firstdose, on day 12 there is still 125mg of test-c remaining. Over thenext 12 days this will release 5.2mg per day into the blood. And 12days after that the remaining 63mg will release 2.6mg per day. Thiscontinues until the depot is completely released.


Of course we are dosing twice per week,so the initial 250mg is joined by another 250mg on days 4, 8, 11,etc. A picture is worth 1,000 words so let's take a look at how this plays out over the course of theentire cycle:



Points of interest:

2. Although we are injecting 500mg per week of testosterone, at no point do blood levels get anyway near 500mg. This actually makes a lot of sense if you think about it. Our natural testosterone production is somewhere around 7-10mg per day. So the 70mg per day peak on this cycle is 10x our natural amount.
3. The cycle peaks at 71.6mg. This peak occurs three time with the first being week 7 day 4.
4. We need to wait until week 2 day 4 for levels to reach 50% of their eventual peak.

Hope this is helpful to others. Also,this is my understanding of the process. Although I believeeverything I'm presenting here is accurate, I may not have it 100%. So any of the vets are welcome to correct me if I'm wrong.

The chart didn't display correctly. Here is an image of the chart:
I would have liked to edit the original post, but the system only allows me to do this for ten minutes.

Very nice. Thanks for that.

And here's the correct graph (the one in the OP was for 500mg test-p dosed 3 times per week). Interesting comparison anyway:

Testosterone Cypionate 500mg per week divided into two weekly does - 8 weeks:



Testosterone Propionate 500mg per week divided into three weekly does - 8 weeks:

Nice thread bro.... Glad to see new guys contributing some intelligent info instead of just askin what sponcor to buy from .

Reps jrock

Cool read indeed. Bravo on putting the time into this.

Sent via Tapatalk Pro.

Some other things to think about based on this data:

1. Consider using an oral for the first two or three weeks. The half lives of most orals are around 6 hrs so peak concentrations occur very quickly.
2. Without a "kick start" carefully considered starting calories. In these cases it really doesn't make sense to start pounding 5,000 kcal on day one. It may be better to ramp up a bulking diet.
3. Although training intensity should always be high, it also may make more sense to slowly increase volume over the first few weeks.
5. Weeks 5-8 are the money weeks! But at this point you've been at it hard for a while. Reach down deep and push everything to another level for the last half.
6. It's been written about several times on this site that gains start to stall around week 8 or 9. This makes perfect sense since steroid concentrations have been at their peak level for a couple of weeks at this point. For longer cycles consider a dosage bump at week 8.

Take another look at the test-c graph. Again, it is not until week 7 that levels finally reach their peak. Before doing this exercise I would have guessed somewhere around week 4.