Hi could anyone give me an idea of what a normal peak flow reading is for a 57 year old female, mine is between 300 - 330.

[McMD]

Peak Flow Normal Range

[Lysistrata Administrator Community Ambassador]

Hi, this depends on your height as well as your age and sex. But it also depends on a lot of other factors! Predicted best is just a start and is based on the average of readings from other people of the same age/sex/height - ideally you need to know what is normal/best *for you*.

For example, my predicted best is around 450-470 but my actual best is 630, probably because I played the oboe for years as a child. However, I still have severe asthma. Someone else my age/sex/height might never blow above 400 but have well controlled mild asthma or even no asthma or respiratory disease at all.

This link gives an idea of the predicted ranges to get you started/as an introduction blf.org.uk/support-for-you/...

This post has a much more detailed look at peak flow and how it works in the real world:healthunlocked.com/asthmauk...

[twinkly29 in reply to Lysistrata]

Yes agree - I so wish much more education was done on peak flow and how

(a) values are only relevant in relation to one's own best

(b) regular monitoring of peak flow is important so that one knows one's own best!

(c) having a high or low best is not indicative of asthma severity or asthma control - that comes from what someone's current pf is compared to their own best (looked at in conjunction with symptoms and other factors as well).

[Chip_y2kuk]

Predicted peak flows are based on age height and gender they don't take anything else into consideration.... however my 30 year old sister who ran 31miles for charity... only blows 400.... so 330 for someone older (peak flows start to drop when you get over a certain age) doesn't sound far from where it should be

[Lysistrata Administrator Community Ambassador in reply to Chip_y2kuk]

Not sure if you were agreeing re the limitations of predicted peak flow, but while predicted values don't take anything else into account, there do seem to be other factors at play on an individual level, though these aren't always well studied currently. There are also population studies on the effect of certain factors on lifetime lung function trajectory ( I'm more aware of studies on FEV1 than peak flow, but peak flow studies may also exist). These show that some factors appear to make a major difference across the lifespan, even in people without respiratory disease.

Very informally and anecdotally, it does seem to make a difference when you did an activity - intense sports or wind instruments or singing starting young seems to make a difference to max peak flow more than taking them up in late adolescence or adulthood.

As far as I'm aware, having certain conditions or some kinds of prior surgery, especially when young, can also make a difference to best peak flow, even if someone is completely well now and doesn't have any respiratory problems.

[Chip_y2kuk in reply to Lysistrata]

I think they have a place but are limited.... for example I used to be able to swim 25 meters at 2 meters deep (holding my breathe for ages, 2 and a half mins ish)... at that time I never ever blew my predicted peak flow, I was always significantly 80-100 l/min lower

And now I'm on enough stuff to sort a cruise ships breathing problems out and k still don't get my predicted peak flow ..... but I now normal for me

[Lysistrata Administrator Community Ambassador in reply to Chip_y2kuk]

There are quite a few potential factors besides age/sex/height that can contribute though, in varying amounts.

With the lung function studies, there were multiple genetic and environmental factors that changed over the lifespan, some becoming more or less important with increasing age and some staying fairly constant. Even if a single factor doesn't contribute much, it's likely that the sum of various different factors will.

Predicted peak flow is a helpful start, but it's quite a blunt tool and should be recognised as such - as you've seen with yours.

Re the breath hold swimming - I also used to be relatively good at that so looked up what factors affect it. Peak flow itself depends on multiple physiological factors including lung volume and elastic recoil. Breath holding physiology (without even involving the exercise component of swimming) is apparently very complex and again multiple factors are involved, including both physiological and psychological. I would imagine the relationship with someone's best peak flow over time just from that is very complex.

[Superzob]

Beware of "normality"! Your PF is a little on the low side (see graph below), but then it's the same as mine and I'm a 6ft man, 71 years old! You need to bear in mind that these figures are averages for a person fitting the description indicated. They represent the centre of a bell curve (not shown) which, in turn, represents what is known as the 95%ile range (ie, the range in which 95% of people, fitting that description, fall into). That is usually 20% either way of the mean figure; so, if your optimal peak flow is supposed to be, say, 400, then 320 (ie, 20% less) is still within the normal range.

The real point is: do you have any ill effects as a result of your particular peak flow? If the answer is no, then it doesn't really matter what it is; if, on the other hand, you feel breathless, then that particular PF is too low for you (bear in mind that some people have theoretically adequate PFs, but still have breathing problems).

As you've probably guessed, I'm not a great believer in treating these figures as gospel - they are a useful guide but, if you have asthma, then measuring the variation in peak flow is a useful way of ensuring it is correctly controlled. Trying to achieve a theoretical PF is pointless, and the stress of failing to do so would probably make the asthma worse!

Peak flow curves