Hi!
I love taking a swim late in the evening... about 45 minutes of the breast-stroke right before bed. It exhausts me, and I have no trouble sleeping through the night (I keep myself well-hydrated during the session, but never eat afterwards). But reading the information posted below, I have to wonder how effective it is at burning fat stores... it sounds as if it depletes glycogen more than anything else. Thoughts? Opinions?
I love taking a swim late in the evening... about 45 minutes of the breast-stroke right before bed. It exhausts me, and I have no trouble sleeping through the night (I keep myself well-hydrated during the session, but never eat afterwards). But reading the information posted below, I have to wonder how effective it is at burning fat stores... it sounds as if it depletes glycogen more than anything else. Thoughts? Opinions?
>> Swimming could increase body fat through the following mechanism:
>>
>>
>> Compared to running and cycling, swimmers burn more sugar and
>> less fat. Swimmers leave a workout more glucose and glycogen
>> depleted. This is a stimulus for eating. Swimmers tend to be hungrier
>> post workout than are runners and cyclists. Controlled studies
>> show that when fat content of post-workout meals are covertly adjusted,
>>
>> there is greater caloric intake than calories burned when higher fat
>> meals are consumed. However, there is greater calories burned
>> than calories taken in when high carb/low fat meals are consumed.
>>
>>
>> Thus, swimming could theoretically result in increased body fat
>> were certain swimmers to unwisely eat high fat meals in the
>> post-workout, glycogen recovery period. There is a greater "risk"
>> of this happening with swimming than with running or cycling because
>> of the relatively greater amount of sugar burning, compared to
>> fat burning.
>>
>>
>> This issue is debated in the Dec 97/Jan 98 issue of Fitness Swimmer.
>>
>>
>> Noted swimming physiologist Costill agrees with me on this.
>> Actually, the evidence is completely consistent and quite
>> persuasive. For starters, the Gwinup study (abstracted below) was very
>> clear
>> cut.
>>
>>
>> 60 moderately obese young (20-40) women. 20 did front
>> crawl and/or back crawl an hour a day 6 days a week for 6
>> months. 20 walked. 20 stationary cycled. Land exercisers
>> lost both weight and body fat. Swimmers lost neither. All
>> groups dropped resting pulse rate to the same degree,
>> confirming equal training effect. This doesn't apply to
>> serious masters competitors, but it certainly does relate to
>> what exercise you recommend to a young, moderately obese
>> woman, who wants to lose weight.
>>
>>
>> Costill studied competitive swimmers, cyclists, and
>> runners. Each did 40 minutes at 70% VO2 max (just sub
>> lactate threshold). Swimmers metabolized sugar almost
>> exclusively and emerged from the water glucose (and
>> presumably glycogen) depleted. Land athletes metabolized
>> substantial amounts of fat and less sugar.
>>
>>
>> This goes well with both evolution and muscle anatomy.
>> Upper body muscle is more "white muscle," with fewer
>> capillaries and mitochondria per unit volume. Also, total
>> volume is much smaller for upper body than lower body muscles.
>> Fat burning absolutely requires capillaries and mitochondria
>> (i.e. "red muscle," as it is exclusively aerobic). Cross
>> country skiers (who equally use and train both upper and
>> lower body), develop significantly more lower body aerobic
>> (capable of fat burning) capacity with training than do
>> their upper body muscles. This fits with evolution, were
>> lower body evolved to meet aerobic demands of migration,
>> hunting, and fleeing. Upper body activity was virtually all
>> anaerobic (sugar burning): i.e. spear throwing, tree
>> climbing.
>>
>>
>> True enough, elite swimmers are all thin and "ripped." But
>> this is selection, not causation. You can't make it to the
>> top without favorable passive drag. Likewise, Whitten's
>> surveys of runners vs. swimmers is selection and not
>> causation. No one who wants to lose weight will stick with
>> a sport where they do not lose weight. Contrariwise, obese
>> people who are losing weight will stick with a sport where
>> the weight loss is occurring, even if they do remain
>> overweight in an absolute sense. So you have a tendency to
>> lose obese swimmers who are swimming primarily to control
>> obesity, while you retain runners who are losing fat, even
>> though they haven't yet achieved slimness. People who
>> stick with swimming long term (like my 84 year old father,
>> who has been a competitive swimmer since 1920), are
>> obviously not those who are predisposed to significant
>> weight gain while doing it.
>>
>>
>> This also does not mean that it is not possible to lose fat
>> through swimming. Obviously, many do. The whole purpose of
>> trying to identify "problems," such as the "fat swimmer," is
>> that if one understands the problem, then one can develop
>> solutions to improve the sport, in this case as a weight
>> loss tool.
>>
>>
>> In the Fitness Swimmer debate, Laughlin says that
>> the way to do this is to avoid eating
>> carbohydrate for 10-12 hours before swimming and then to
>> swim for a long time at only 60% of maximum effort. I don't
>> agree at all with this. In the first place, the 60% effort
>> as continuous motion is probably pretty close to what
>> Gwinup's moderately obese young females were doing.
>> Secondly, the carbohydrate avoidance is exactly the opposite
>> of what a swimmer desiring weight loss should be doing.
>>
>>
>> This whole idea of eating fat to promote fat burning is
>> absurd. Sure enough, eat more fat and you will burn more
>> fat, no doubt about it. But you never burn more than the
>> extra dietary fat you are taking in. What does it profit a
>> swimmer to eat 3 extra grams of fat in order to burn 2?
>> What you would like to do is eat three extra grams of fat
>> and then burn 4, but that doesn't happen. And you can lose
>> fat by burning carbohydrate when you exercise; you don't
>> have to burn fat during exercise to lose fat. And eating
>> carbohydrates does not make you fat. There have been
>> many studies of high carbohydrate diets and not a single one
>> has ever shown weight gain, and most show weight loss, as
>> long as the diet is followed. And the world's largest
>> registry of people who have successfully lost 30 pounds and
>> kept it off for more than 5 years shows that the successfull
>> weight losers were primarily eating a high carbohydrate
>> diet. Sears says that the "fatterning of America," is owing
>> to eating less fat and more carbs. This is not true.
>> Between 1960 and 1976 average American calories as fat
>> consumption decreased from 39% to 36%. There was no
>> significant increase in obesity. Between 1976 and 1994, fat
>> consumption decreased further from 36% to 33%. Obesity
>> zoomed. But what also happened during this time was that
>> average TV viewing time increased to 4.4 hours per day per
>> person (cable TV, VCRs, Blockbuster Video), use of public
>> transportation (requires walking) fell significantly, school
>> children physical fitness scores plummeted on standardized
>> testing, and per capita sugar consumption increased by 20-30
>> pounds per year. Also huge numbers of people quit smoking.
>>
>>
>> What about insulin inhibiting fat mobilization and
>> inhibiting fat burning? Sure enough, it does this, but it is
>> very temporary. And carbohydrate gets converted to fat and
>> stored as fat at only 76% efficiency, while fat gets stored
>> as fat at 98% efficiency. And when you covertly adjust the
>> fat content of post exercise meals, you end up with a net
>> burning of calories when high carb food is eaten, but with
>> no net burning of calories (calories burned during exercise
>> minus calories taken in after exercise) when higher fat food
>> is eaten.
>>
>>
>> So what do you fear more, an "insulin spike" after a
>> carbohydrate meal which has a _temporary_ inhibiting effect
>> on fat burning, or a "fat spike" (i.e. postprandial
>> hypertriglyceridemia) in which extra fat is absorbed
>> (because extra fat is taken in at mealtime), which must then
>> be disposed of or stored (at 98% efficiency)?
>>
>>
>> What is the difference between having a high insulin level
>> for one hour or a high load of recently-absorbed fat for one
>> hour? Actually, the insulin goes promptly back to baseline.
>> The post-prandial triglycerides stay around longer, while
>> they are searching for fat cells to go hide in.
>>
>>
>> So here is really why swimming makes it tough to lose
>> weight...it doesn't really have all that much to do with fat
>> burning, per se, as it has to do with energy balance
>> (calories burned minus calories taken in after exercise).
>>
>>
>> Swimming burns sugar and leaves muscles glycogen depleted,
>> this is a powerful stimulus to hunger. Our club's age group,
>> USS senior, and masters swimmers talk about being
>> "famished" when they are getting dressed after their
>> workouts.
>>
>>
>> But walk from our club pool 200 yards over to the nearby
>> community college track and talk to the track athletes who
>> have just completed a typical workout of mixed intervals or
>> come back from a long run. The last thing they want to do
>> is eat a big meal. Why is this? Well, the swimmers have
>> depleted their muscle glycogen, and are hungry to replete
>> it. If they are foolish enough to try and replete it with
>> 30% fat/30% protein/40% carbohdrate, they will be eating a
>> lot of unnecessary calories to try and build back up their
>> muscle glycogen. The track athletes, in contrast, have
>> burned less glycogen and more fat. Products of fat
>> metabolism (ketones) are appetite suppressing.
