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Body-fat percentage

pbt150pbt150 Posts: 338
edited November 2008 in Training, fitness and health
I'm 22, and I've just had my body fat percentage measured for the first time (at a University sport science lab). I'm 5'10", 71 kg, and am 12.5% fat. I was wondering what a safe amount of weight would be to lose over the winter - what sort of BFP do fit athletes tend to carry, and would losing a few pounds help come next summer?

Posts

  • damage36damage36 Posts: 282
    12.5kg is in the healthy range, and is pretty respectable. Elite athletes are around 8-10% but you don't want to get too cold this winter! I wouldn't go nuts on your BFP just yet.
    Legs, lungs and lycra.

    Build a man a fire, and he'll be warm for a day. Set a man on fire, and he'll be warm for the rest of his life.
  • azzerbazzerb Posts: 208
    I wouldn't worry too much about it. If you're doing it for aesthetics, just keep losing the fat (don't forget to include weight sessions to retain muscle mass), I usually get to a point where i'm more noticeably less energetic/insanely hungry a lot, so i know when to stop cutting down.
  • Al_38Al_38 Posts: 277
    First of all - you need to have reason to want to lose body fat 12.5% is a perfectly sensible and healthy figure. I would advise against trying to lose it coming in to the winter though, from personal experience this will make you cold and miserable and more than likely ill more frequently too. It would be better to start doing this (if at all) once it starts getting warm again. If you did lose a bit, I would suggest you probably wouldn't notice the difference - it is a very gradual change. So while you might be a little quicker up the hills (due to being lighter i.e. increasing power to weight) you most likely won't notice as you can't directly compare. There are some downsides too - you have less places to put lactate and so high intensity work will hurt a bit more (in theory), also you have to be much more careful about fueling - it is very easy to simply run out of glycogen and then you will feel completely addled.

    Secondly, very few of the tests are especially good at measuring body fat levels:
    If it used electrodes then it can be altered significantly by how well hydrated you are and how hard the electrodes were attached to your skin.
    Calipers where they take skin fold measurements of illiac, bicep, tricep and scapula (normally) only measures subcutaneous body fat levels. This still has issues in that unless you are calipered in exactly the same place each time by the same person using the same technique, it is possible to get different readings.
    The only test that works properly AFAIK is to weigh yourself then to be submerged in a tank of water and have you weight taken again (after exhaling all possible air from your lungs) - at this point fat should be the only thing less dense than water, so you should get a true body fat measurement

    As to what you can get down to? you need a minimum of 4% to survive but this is an absolute minimum - in practice you shouldn't try to go below 6%. Even at this level you get very ill very easily and have to be exceptionally careful. Based on the figures you gave your 6%fat mass is somewhere around 66 - 67kg (this depends on how much weight you had in your stomach / intestines when tested). Personally I think most athletes go lower than the 8-10% level. Principally I am a lightweight rower and come the racing season in the summer will be around 7% BF or so - this is purely to make weight - there is an individual maximum of 72.5kg and a crew average maximum of 70.0kg. Even at these levels I would suggest that most of the professional cyclists are lower than that.
    We have a lot of support in the squad for this - our own dietician and regularly have weigths and skinfold measurements taken, to make sure it has as little impact on health as possible.
    Without this level of support I would not advise actively trying to lose BF.

    Al
  • pbt150pbt150 Posts: 338
    AI - the main reason I asked actually was because I am also a lightweight rower (who cycles), and I was having a chat with my coach just after having my measurements taken. We've got a couple of quite big guys in the squad so I'm clearly going to have to go a couple of kilos under 70 to make up for them. Then, once the summer arrives I'm quite keen to keep that level of fitness so I'm going to spend a lot of time cycling, so I'm interested in the weight for rowing and getting up hills quickly.
  • Al_38Al_38 Posts: 277
    OUL??
    I would imagine that you will find the weight / BF comes off under the training load - it will be a gradual change.

    AL
  • pbt150pbt150 Posts: 338
    Yeah, OULRC, are you CULRC by any chance?

    TBH I am finding it hard to keep the weight on ATM, I was just curious how low a BFP was considered unhealthy.

    FTT.
  • damage36damage36 Posts: 282
    edited November 2008
    pbt150 wrote:
    Yeah, OULRC, are you CULRC by any chance?

    TBH I am finding it hard to keep the weight on ATM, I was just curious how low a BFP was considered unhealthy.

    FTT.

    Come on the light blues! Seriously though, cambridge haven't won in years, do we have a granta (culrc 2nd VIII) this year?
    Anyway, I can't say too much, rowing for selwyn isn't such a big deal :P
    Legs, lungs and lycra.

    Build a man a fire, and he'll be warm for a day. Set a man on fire, and he'll be warm for the rest of his life.
  • Al_38Al_38 Posts: 277
    damage36 wrote:
    pbt150 wrote:
    Yeah, OULRC, are you CULRC by any chance?

    TBH I am finding it hard to keep the weight on ATM, I was just curious how low a BFP was considered unhealthy.

    FTT.

    Come on the blues! Seriously though, cambridge haven't won in years, do we have a granta (culrc 2nd VIII) this year?
    Anyway, I can't say too much, rowing for selwyn isn't such a big deal :P

    I think the crucial missing word is "light" :wink:
  • sward29sward29 Posts: 205
    Al_38 wrote:
    ]There are some downsides too - you have less places to put lactate and so high intensity work will hurt a bit more (in theory),
    Al

    Not sure that bodyfat has any role in lactic acid accumulation or clearance.

    In terms of perfomance gains, Cycling Weekly recently suggested that a 3kg reduction in mass on a long climb (bodyfat rather than lean mass) offers the same improvement in climbing performance as a 10 watt increase in functional threshold power. Obviously it is ideal to reduce bodyfat and improve FTP but I would suggest that you focus upon improving cardiovascular fitness rather than focussing too heavily upon bodyfat unless it becomes critical to your rowing.
  • Al_38Al_38 Posts: 277
    sward

    I wasn't suggesting that fat did anything special with lactatic acid - as i understand it when you start generating lactic acid at a rate that you can't clear it from muscle mass, it essentially sits near where it was generated. If you have less tissue there for it to sit in then you end up with a higher concentration of lactic acid per unit tissue. So it hurts a bit more.

    This is just what I have picked up - maybe somebody with a better understanding of physiology could explain it better / tell me I am completely wrong!

    With regards to rowing I suspect both CUL and OUL do very similar amounts of training - with a lot of work done to improve CV fitness. However unlike cycling, summer rowing races take place over a 2k stretch of water which takes around about 6 minutes (roughly) to complete - i.e. there is more of an anerobic element to it. BFP comes into it because when there is an average maximum weight to make, you want to have as much power as possible. So as little useless weight (fat) as possible
  • pbt150pbt150 Posts: 338
    damage36 - as far as I know you guys aren't fielding a Granta this year, and our reserves (Nephthys) are going to row over for the third and final time before the event is retired from the Henley Boat Races.

    As far as weight goes, the aim is to race at the minimum weight you can whilst at full strength - you don't want any excess weight that doesn't help move the boat. I guess it's the same principle as cycling up a hill, in that you don't want to have to carry any weight you don't need. I'm just trying to work out where that is for me, and given the fact we're training pretty hard I shouldn't have much trouble both losing the BFP and increasing my FTP. Seriously, if anyone's looking for a good way to improve their cycling, give rowing a go, it's great!

    Oh yeah, and FTT :) .
  • damage36damage36 Posts: 282
    pbt150 wrote:
    damage36 - as far as I know you guys aren't fielding a Granta this year, and our reserves (Nephthys) are going to row over for the third and final time before the event is retired from the Henley Boat Races.

    As far as weight goes, the aim is to race at the minimum weight you can whilst at full strength - you don't want any excess weight that doesn't help move the boat. I guess it's the same principle as cycling up a hill, in that you don't want to have to carry any weight you don't need. I'm just trying to work out where that is for me, and given the fact we're training pretty hard I shouldn't have much trouble both losing the BFP and increasing my FTP. Seriously, if anyone's looking for a good way to improve their cycling, give rowing a go, it's great!

    Oh yeah, and FTT :) .

    FTT? I think I'm missing something here...
    Legs, lungs and lycra.

    Build a man a fire, and he'll be warm for a day. Set a man on fire, and he'll be warm for the rest of his life.
  • Al_38Al_38 Posts: 277
    F**k the tabs...

    our nearest equivalent is GDBO
  • pbt150 wrote:
    Seriously, if anyone's looking for a good way to improve their cycling, give rowing a go, it's great!
    Seriously, if anyone's looking for a good way to improve their cycling, then ride a bike!!

    As for body fat & power.

    My advice would be to train to improve your sustainable aerobic power. Provide you eat well, then your fat % / weight will look after itself.
  • MichuelMichuel Posts: 269
    pbt150 wrote:
    I'm 22, and I've just had my body fat percentage measured for the first time (at a University sport science lab). I'm 5'10", 71 kg, and am 12.5% fat. I was wondering what a safe amount of weight would be to lose over the winter - what sort of BFP do fit athletes tend to carry, and would losing a few pounds help come next summer?

    Just to add some stats to the debate :-

    There's been a lot of studies of pro racing cyclists. These stats are of 14 in a minor Spanish team in 2000 Vuelta where the test was to assess intensity of effort on climbs.

    BodyMass70.1kg (+-1.5)Height180.2cm (+-1.6)BodyFat7.3%(+-0.2)VO2Mx/kg80.2+-(1.6)

    18 Top class world pro cyclists (Indurain?)
    BodyMass68.6kg (+-4.89) Height 177.1cm(+-4.1) Fat 8.08%(+-1.4)(min6.5% max 11.3%)


    McKardle,Katch,Katch(1991) summarise body fat% for different sports:-

    MarathonRunners BodyMass 59.4kg BodyFat 3.3%
    Gymnasts BodyMass 69.2kg BodyFat 4.6%
    Swimmers BodyMass 79kg BodyFat 6.8%
    ProRoadCyclists BodyMass 71.3kg BodyFat 11.6%
    DistanceRunners BodyMass 67.2kg BodyFat 11.8%
    Sprinters BodyMass 74.1kg BodyFat 16.5%

    FemaleDistanceR BodyMass 55.1kg BodyFat 17.2%

    In same book from Tokyo/Mexico Olympics:-

    MarathonRunners BodyMass 60.8kg BodyFat 2.7%
    Sprinters BodyMass 72.2kg BodyFat 10.1%
    Distance (10k) BodyMass 59.8kg BodyFat -0.5%
    RowingSingle,Dbl BodyMass 82.2kg BodyFat 14.1%

    The contribution weight loss gives to cycling derives from the usual watts/work equation where road friction and wind resistance can be dropped (they're about 10%) on a mountain as speeds low. Thus percent reduction in weight divided by total weight of bike, equipment rider gives percent time saving. This can be worked out accurately using the many models on web such as AnalyticCycling as the models standard.-

    Jeukendrup (Rabobank consultant & UoB professor) estimated effect of 3kg weight reduction for Novice, Trained, Elite riders for 3%, 6%, 12% slopes on 20km climb:-

    Novice 3% 1m34s 6% 3m38s 12% 7m25s
    Trained3% 42s 6% 1m52s 12% 4m2s
    Elite 3% 29s 6% 1m15s 12% 2m48s
  • Michuel wrote:
    Jeukendrup (Rabobank consultant & UoB professor) estimated effect of 3kg weight reduction for Novice, Trained, Elite riders for 3%, 6%, 12% slopes on 20km climb:-

    Novice 3% 1m34s 6% 3m38s 12% 7m25s
    Trained3% 42s 6% 1m52s 12% 4m2s
    Elite 3% 29s 6% 1m15s 12% 2m48s
    That would be better expressed as:
    - per km improvement in absolute time (e.g. sec/km), and
    - the % improvement, which, for the reasons you have stated, would be approximately the same no matter the level of cyclist (provided they are the same mass to start with).

    The greatest variations in % improvement will be on the lesser gradients since pace is higher and aero resistance plays a slightly larger part in the equations.
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