Explain the terminal Length concept to me

[khrystyne572]

So I've been reading here about Terminal Length, and that after a certain period of time your hair enters telophase and stops growing.

But, your hair eventually comes out of telophase and begins growing again right? Or not? What triggers telophase? The weight of your hair on the follicle, or just some mysterious time clock hidden in the genes? Is it preset like leg hair to just grow a certain amount and be done?

How long will hair sit in telophase and have no growth? Lets say that a person's hair is on an eight year cycle- meaning it grows for eight years and then hits telophase- does that mean it grows for eight years and then takes an eight year break?

I'm confused.

[WildEagle]

Oooh great question Khrystyne! Unfortunatly I don't have these answers at all, so will be keeping an eye on this thread.

I just wanted to add another question to your post that maybe someone could answer too...
Is there an 'average' terminal length in which the majority of people have? Would most stop at around the same length, and then very few have the special genes to grow longer?
If so, what is the average terminal length?

[pixiedust]

I got this one. Give me a second to type up an explanation

ETA:

There are three phases of hair growth, the Telogen phase being the last one. A hair goes through all three phases (and they all do, eventually) and then releases from the follicle, or the 'root', which is a tiny 'pocket' that hairs grow out of (like your pores). Each hair follicle is said to go through about 20 or so of these growth cycles in a life time (EDIT: this is questionable information) The cycles of growth are:

Anagen
The anagen phase is known as the growth phase. It begins in the papilla (this is basically another word for the hair follicle or hair root) and can last around eight years. The longer the hair stays in the anagen phase, the faster and longer it will grow. During this phase, the cells in the papilla divide to produce new hair fibers, and the follicle buries itself into the dermal layer of the skin to nourish the strand. About 85% of the hairs on one's head are in the Anagen phase at a given time.

Catagen
When the anagen phase ends, the catagen phase begins. The catagen phase, also known as the transitional phase, allows the follicle to, in a sense, renew itself. During this time, which lasts about two weeks, the hair follicle shrinks due to disintegration and the papilla (or root) detaches and "rests", cutting the hair strand off from its nourishing blood supply. Although the hair is not "growing" during this phase, the length of the hair fibers continue to increase when the follicle pushes them upward. These hairs usually don't shed, but they don't "grow" as fast as hairs in the Anagen phase. This is the shortest cycle, lasting about a month, and only about 3% of hairs are usually in this cycle at once.

Telogen (the one you're talking about)
During the telogen, or resting, phase the hair and follicle remain dormant anywhere from 1–4 months. 10%-15% of the hairs on one's head are in this phase of growth in any given time. 70 percent of hair prematurely can enter a phase of rest, called the telogen phase. Three months later, these hair begin to fall. The Anagen phase begins again once the Telogen phase is complete. The preceding hair strand is pushed up and out by the new, growing strand. The process causes the normal hair loss known as shedding.

That was all mostly stolen from wiki, but I edited it because the article wasn't 100% factual (in comparison with my book on Trichology) and I wanted to make sure it was a little easier to understand.

These are some of the things that affect hair growth cycles:

1. Stress, diet, sleeping habits, medications, illnesses, body weight, etc etc. I can't go much into detail about how because this post would become entirely too long, but if you dig in the forums for a little while you can find out more. Personally, I've only found that stress and diet have been significant factors in my personal growth rate/quality of hair (I am slightly underweight and it hasn't slowed my growth, caused my hair to thin or become brittle etc).

2. The harsher you are with handling hair, the more likely it is to prematurely enter the telogen phase (aka, pulling out hairs while combing/brushing that aren't quite ready to fall) and this sort of relates to my next point...

3. While haircuts and breakage don't necessarily effect your growth cycles, they shorten hairs that should technically be longer, which can appear to be "premature shedding" when really, a hair is falling out at a terminal length of 12" and not, say, 40" because it was cut/broken several times throughout its growth cycle. This is why many people who first start on LHC (or women in general) think that they have a terminal length that is much shorter than it really is.

4. Chemical and Mechanical damage. See number 3.

5. Genetics and Hormones have been said to be a big factor in how long a hair stays in the Anagen phase. Science has found in studies that Estrogen (female hormone) has a lot to do with having healthy, thick hair. Certain male sex hormones (both men and women have them, in varying amounts) like Androgens (sometimes called DHT) in excess in the body can cause hair to fall and not grow back, for some reason; More often than not, it seems to be a lack of estrogen rather than an excess of Androgens that causes hair to fall prematurely. This is why you see a lot of little girls with baby fine, super thin hair. This premature hairfall is called Loose Anagen Syndrome, where hair falls or can be pulled out in all growth phases. Usually, this corrects itself with age. If it doesn't, things can be done about it to reduce premature shedding (ie, careful handling, birth control, etc etc)

Anyways, most people's terminal length (if I remember correctly) is somewhere around 45" or tailbone. Some women can grow their hair longer (I couldn't tell you why, there's not really any science-proven reason yet to my knowledge.) Keep in mind that a woman who is 5'11 might have the same length of hair as a woman who is 5'0 tall (for example, 40" in of hair) but the tall woman's hair would appear shorter, say TB length, where the shorter woman has less height; thusly the same length on her would appear to be, say, knee length. For example, Crystal Gayle is a famous country singer who is known fr her very very long hair, but she IS only 5'2. I'm not saying that this is ALWAYS a factor in terminal length, but it's something to think about.

Wow, that was really long, sorry. Hopefully this was helpful (If you can bear to read it all, haha.)

Anybody who sees something in here that they want to ask questions about, feel free. Also, if I missed something or if information is incorrect, let me know and I'll correct it asap. Thanks (:

[mathnerd]

I'm kind of interested by this topic as well. Will wait for your explanation too pixiedust! lol

[Nevvie]

You have to think of each individual strand (and follicle) of hair as a separate entity. Each strand has a life cycle. They don't all grow at the same rate or fall out at the same time. At any given time usually about 85% of your follicles are in various stages of the growing phase, anywhere from not yet breaking past the skin on your scalp to the longest strands and everywhere in between.

Anagen Phase is the growing phase. This phase lasts for years, but each person is different. Catagen Phase (which only lasts a week or two) is an in between phase where the follicle shrinks and starts to break apart. Telogen Phase is the resting phase and the end of a follicles life cycle. This last phase usually only lasts for a few weeks. When it's over the strand of hair will either fall out or be pushed out by the new strand of hair that has begun growing in the follicle.

Everyday you shed a few of the oldest hairs and gain a few brand new ones. Terminal length is the maximum amount of growth that a strand can reach before falling out and being replaced. Some strands will grow slightly faster or slower than others and some strands are considerably older than others, which is why not every hair on your head is the same length.

[ilovelonghair]

Each hair follicle goes through about 20 or so of these growth cycles in a life time (but this is just an estimation.)

So if you'd wax your legs 20 times (with letting the hair grow back fully each time after) would mean you can get rid of leg hair forever? No wait, that wouldn't make sense, leghair doesn't even grow that long so each phase is much shorter, that would mean you'd run out of leghair pretty soon in life. Not true!

I'm trying to calculate something and I am terrible with numbers, so if anyone can help please :
the average person (man or woman) can grow their hair 45", I assume thats LHC lenght and not the actual lenght of a single strand. From what I could find out from Google, average hair grows 70-90 centimeters (27.6"-35.4") before it falls out. And most hair grows 1 centimeter a month. So wouldn't an average person 'run out' of hair before they die, if you calculate how often a hair can grow, how many years it grows and the phases in between? (using the numbers provided)

[Juicematic]

Very interesting! I've seen terminal length on some members stats and wondered about it. Thanks to everyone for the excellent explanations.

[spidermom]

Once a hair stops growing, it doesn't start growing again. It sheds out.

The 3 phases of hair growth have already been explained very well. You will notice that most of the people who have terminal length hair have a lot of taper at the ends. Sometimes there is one longest hair because that one either has a longer growth cycle than other hairs, grows faster than other hairs, or both.

I did have a roommate in the past whose hair never got longer than BSL in all the 8 years that I knew her. She didn't cut it and she didn't abuse it, so I can only conclude that most of her hairs had growth cycles that ended at about 3 years. She didn't have much taper either. It was kind of strange, and she was so frustrated because she wanted to have really-really-really long hair. It just wasn't in the genes for her.

[WildEagle]

Thanks Pixiedust for all that helpful info...the OP got me very curious about this!
I understand a whole lot more now, thanks

[Kiwiwi]

@pixiedust

That was super interesting, thank you so much! ^_^