1) Official Race Results
NAME:
Dxxxx Sxxx
EVENT:
Full Marathon
DATE:
Sunday, December 2nd, 2007
BIB/DIV:
6xx / M3539
TIME:
4h:22m:51s (gun) / 4h:21m:57s (net)
Splits (acc to timing chip)
Time Start: 5:31:06
7k700m: 12:46:35
21k: 2:01:08
26k750m: 2:29:46
Gun time: 4:22:51
Chip Finish: 4:21:57
Average Splits: 6m12s/km
Rank: 1002 (FM-Males), 1127 Overall
Link here --> http://www.runpix.biz/sin07/42/finord.php?LastName=632&lan=&aset=0
Splits (acc to Polar)
10k: 00:57:22
21.1k: 2:00:23
28k: 2:40:26
42.2k: 4:21:59
2) Visit to Atlas Chiropractic
I went to see my chiro on Tuesday evening after the race. By then still had soreness mainly over the quads, and a little tightness of the hams. Left knee pain had almost totally gone, phew! Didn't want a repeat of the ITB problem I had last time out.
Had me up on the table and gave me the once over. Hip was out of alignment he said, contributing to a limb length discrepancy (L>R). Did the usual side-pulling with all the crackling coming from the nether regions of the back and hips. Don't ask me how it works, but it works! The hip and quad pain significantly reduced with a 5-minute procedure. Next, worked on my ankles, again the twisting and crackling. Last, worked his way up to my shoulders. Now, I hadn't mentioned my shoulder and upper back cramps during the race, but Terence picked up on it straight away. More pulling and crackling.
All in all, felt looser and less achy after the session. Terence asks for some advice on training, wants to do the full next Dec! Gotta to remember to send him some stuff.
Wednesday, December 5, 2007
Monday, December 3, 2007
SCSM 2007
Race Report
My Race:
Felt quite undertrained for this event. Compared to previous 2, total mileage is probably down by about 20%, longest LSD short by 3k. Only saving grace is some speed work done. Also, tried a late taper as suggested by RW. My thoughts on this are a little mixed. I think my last LSD, a week later than I would usually run it, was probably about 3-4 days too close to the event. On the other hand, I think it did provide me with a much needed training boost. It may mean I will need to split the difference and run it mid-week in future.On the morning itself, still feeling a little leg heavy from fairly hard training 2 weeks prior, plus chasing the kids whole of Sat.
Got on the bus, and was at the esplanade shortly thereafter. True to my usual routine, queued for the esplanade toilets, thankfully still empty at around 4.50am. Nothing to pass out though, despite sitting on the bowl for a good 10 minutes.Had my last drink of 100plus, took half a banana and went to pee one more time at a porta-loo. Time was 5.15 and I made may way to the start line. Saw Sealboon on the side of the sub-4 pen, seemed very focussed so I did not trouble him. Didn't recognise anybody else.
Horn blows, away we go. First couple of clicks going as it typically does, some speedsters streaking away, some slowbies who have decided that they need to start in front, but the wide open avenue makes it less painful for everone. Stop at the telok ayer market toilet for a pee, good to get this out of the way early! Once the adrenaline kicks in, urine output will be minimal and I don't expect to need to use the loo anymore for the rest of the race. For the first 10k, fairly uneventful, was walk-breaking more frequently than expected as I couldn't properly identify stations with isotonic, so pretty much every water point I slowed downed to take a swig. Unfortunately, that meant each walk break was shorter than usual. Did this contribute to the crash? Maybe. Out of marina south and past the esplanade again. Huge crowds, which was nice and a good boost at this part of the race. Going better than expected at this point, clocking 5:30-5:40 pace and at the halfway point time was 2:01, just a little off my AHM 2007 timing. HR still under 162 average.
Now fully into the East Coast Park. Support was tremendous! Thank you volunteers. Was tracking an older gentleman who was running bow-legged. He was fast enough but I wonder what sort of impact this type of running biomechanic would hold for his knees in the future. At the 23km point, I see Freddy coming back own the other direction. Holy cow! What a smoking quick run he was doing! I am beginning to feel it. Pace average dropping off, now around 5:40-5:50 per km. Made the u-turn, back towards the city. The sun is now high enough to make a difference. I stretch my arms a little, and BANG, my whole upper back and shoulders cramp up. It was excruciating in the extreme and I almost stop running. I hang my arms down and push on. Pace is now 6+min/km. Legs are getting noticeably heavier, at 28km, its 2:41, still on target for a sub-4. A short while later, twing, and my left calf seizes momentarily. Oh no, the dreaded cramps. I've blown it, it was going to be a real struggle from here. And indeed, when I hit this wall, the fall was precipitous. In a matter of 1km, left calf, left thigh, right thigh, left hamstring, all started to threaten to cramp. I slow to a walk-run. For the first time, I gratefully accept deep heat, I have never ever used that stuff before. It seemed to work and the worst of the cramps were staved off. I mentally prepare myself to struggle for another 12km.
The rest of the way was pure agony, basically completely played by ear, shuffled when I could, walked when my legs refused to respond, stopped at almost every drink station. My lack of training and over-ambitious start had caught up with me. No chance of my heart giving out, now ticking along at 145/min, not even 85% max! Definitely the legs are rate limiting. Amazingly, still averaging around 7:30/km. I was going to come in PB! The last 500m, picked up to a decent trot so that I don't look too bad in the pictures :p.
Completed in 4:22.A PB by 6 minutes, despite being undertrained, hotter weather, less rest and being 3kg heavier. I think with a more discliplined and smarter program, better taper and race strategy, a sub-4 will be achievable by next year end. 2008 will be the year to try. Perversely, I felt as good about myself for having struggled through the last 12km and having run a good pace for the first 30!
Organisation:
Overall, a 9/10 for the organisers. Bag check was smooth and painless. Porta-loos seemed a plenty. Start point management was also pretty smooth with a nice clear avenue for folk to get to their starting pens. A 5.30 start is good, gives us a chance to get the miles in before the full brunt of the morning heat. Have not actually run the full in SG before, but apart from the first 10k in the quiet of Marina South, the rest of the way was quite well supported. Drink stations were plentiful, although it wasn't clear which had isotonic and which did not. Made my drink stop strategy a little messy. At the end, bag collection was a cinch. Well done organisers! Some feedback for improvement below.
Feedback to organisers
a. Get pacers positioning right
b. Get isotonic on all stations, or at least post in advance which stations will have them
My Race:
Felt quite undertrained for this event. Compared to previous 2, total mileage is probably down by about 20%, longest LSD short by 3k. Only saving grace is some speed work done. Also, tried a late taper as suggested by RW. My thoughts on this are a little mixed. I think my last LSD, a week later than I would usually run it, was probably about 3-4 days too close to the event. On the other hand, I think it did provide me with a much needed training boost. It may mean I will need to split the difference and run it mid-week in future.On the morning itself, still feeling a little leg heavy from fairly hard training 2 weeks prior, plus chasing the kids whole of Sat.
Got on the bus, and was at the esplanade shortly thereafter. True to my usual routine, queued for the esplanade toilets, thankfully still empty at around 4.50am. Nothing to pass out though, despite sitting on the bowl for a good 10 minutes.Had my last drink of 100plus, took half a banana and went to pee one more time at a porta-loo. Time was 5.15 and I made may way to the start line. Saw Sealboon on the side of the sub-4 pen, seemed very focussed so I did not trouble him. Didn't recognise anybody else.
Horn blows, away we go. First couple of clicks going as it typically does, some speedsters streaking away, some slowbies who have decided that they need to start in front, but the wide open avenue makes it less painful for everone. Stop at the telok ayer market toilet for a pee, good to get this out of the way early! Once the adrenaline kicks in, urine output will be minimal and I don't expect to need to use the loo anymore for the rest of the race. For the first 10k, fairly uneventful, was walk-breaking more frequently than expected as I couldn't properly identify stations with isotonic, so pretty much every water point I slowed downed to take a swig. Unfortunately, that meant each walk break was shorter than usual. Did this contribute to the crash? Maybe. Out of marina south and past the esplanade again. Huge crowds, which was nice and a good boost at this part of the race. Going better than expected at this point, clocking 5:30-5:40 pace and at the halfway point time was 2:01, just a little off my AHM 2007 timing. HR still under 162 average.
Now fully into the East Coast Park. Support was tremendous! Thank you volunteers. Was tracking an older gentleman who was running bow-legged. He was fast enough but I wonder what sort of impact this type of running biomechanic would hold for his knees in the future. At the 23km point, I see Freddy coming back own the other direction. Holy cow! What a smoking quick run he was doing! I am beginning to feel it. Pace average dropping off, now around 5:40-5:50 per km. Made the u-turn, back towards the city. The sun is now high enough to make a difference. I stretch my arms a little, and BANG, my whole upper back and shoulders cramp up. It was excruciating in the extreme and I almost stop running. I hang my arms down and push on. Pace is now 6+min/km. Legs are getting noticeably heavier, at 28km, its 2:41, still on target for a sub-4. A short while later, twing, and my left calf seizes momentarily. Oh no, the dreaded cramps. I've blown it, it was going to be a real struggle from here. And indeed, when I hit this wall, the fall was precipitous. In a matter of 1km, left calf, left thigh, right thigh, left hamstring, all started to threaten to cramp. I slow to a walk-run. For the first time, I gratefully accept deep heat, I have never ever used that stuff before. It seemed to work and the worst of the cramps were staved off. I mentally prepare myself to struggle for another 12km.
The rest of the way was pure agony, basically completely played by ear, shuffled when I could, walked when my legs refused to respond, stopped at almost every drink station. My lack of training and over-ambitious start had caught up with me. No chance of my heart giving out, now ticking along at 145/min, not even 85% max! Definitely the legs are rate limiting. Amazingly, still averaging around 7:30/km. I was going to come in PB! The last 500m, picked up to a decent trot so that I don't look too bad in the pictures :p.
Completed in 4:22.A PB by 6 minutes, despite being undertrained, hotter weather, less rest and being 3kg heavier. I think with a more discliplined and smarter program, better taper and race strategy, a sub-4 will be achievable by next year end. 2008 will be the year to try. Perversely, I felt as good about myself for having struggled through the last 12km and having run a good pace for the first 30!
Organisation:
Overall, a 9/10 for the organisers. Bag check was smooth and painless. Porta-loos seemed a plenty. Start point management was also pretty smooth with a nice clear avenue for folk to get to their starting pens. A 5.30 start is good, gives us a chance to get the miles in before the full brunt of the morning heat. Have not actually run the full in SG before, but apart from the first 10k in the quiet of Marina South, the rest of the way was quite well supported. Drink stations were plentiful, although it wasn't clear which had isotonic and which did not. Made my drink stop strategy a little messy. At the end, bag collection was a cinch. Well done organisers! Some feedback for improvement below.
Feedback to organisers
a. Get pacers positioning right
b. Get isotonic on all stations, or at least post in advance which stations will have them
Sunday, December 2, 2007
Personal Journal (SCSM2007)
This will be a long entry to reflect the prep I had for this race and also my observations of race-day events and my own performance.
1) Prep
I hadn't expected to do the SCSM this early in my running 'career'. Both of my marathons to date had been in the US in freezing temperatures. I had wanted to 'save' the SCSM to a later time I had started to run out of events to take part in. Ah well, events conspired to render my participation in US races difficult. Hadn't been travelling as much and had lingering ITB problems from the previous event in Chicago from Oct 2006, and therefore had pathetic mileage in training. So in July of this year, signed up for the local marathon. About this time, was when I became more active in SGRunners forum. So set up a 5 month programme, entered the AHM and NB realrun for prep, and determined to do a good one. No preset idea of what time to complete in, just needed to make sure I give a good account of myself.
2) Training
See above
6) Learning points
a. Get technical running socks
b. Use a cap/visor
c. Start taper 16-19 days before, last LSD no closer than 19 days to event.
d. Arm pouch is a no-go
e. Don't compromise on walk-breaks early on
f. Fibre diet is ok pre-race
g. Does deep heat help?
1) Prep
I hadn't expected to do the SCSM this early in my running 'career'. Both of my marathons to date had been in the US in freezing temperatures. I had wanted to 'save' the SCSM to a later time I had started to run out of events to take part in. Ah well, events conspired to render my participation in US races difficult. Hadn't been travelling as much and had lingering ITB problems from the previous event in Chicago from Oct 2006, and therefore had pathetic mileage in training. So in July of this year, signed up for the local marathon. About this time, was when I became more active in SGRunners forum. So set up a 5 month programme, entered the AHM and NB realrun for prep, and determined to do a good one. No preset idea of what time to complete in, just needed to make sure I give a good account of myself.
2) Training
What would I do different this time? I thought speed work was the key. Previously, being a marathon newbie, was pretty nervous about completing the event even, without looking like a complete idiot. Naturally the focus was on getting in those long miles to build up an aerobic and endurance base. The consensus from many different books and websites was that in order to run fast, you really had to train fast. How fast? I thought a 4:00-4:10 finish was a reasonable target, given my previous PB of 4:28. This time round, made sure I had at least 1 speed session per week, which usually ended up being hill repeats. Also, wanted to continue to build up an even better aerobic base. Alas, reality collides with theory, at the end of the day, only managed one LSD > 30km and 2 runs > 25km. All in all, would have considered myself significantly undertrained for the event.
Also, tried a shorter taper with my last LSD coming only 2 weekends before the event. It was probably a little too close for me.
Also, for the first time, used a camelbak for a few of my runs. I must say, it is a nifty invention. Will definitely make more use in the future. Mine is a small 1.5L version, but in truth could probably take 1.2L at most if it was to be used comfortably. When filled fully was pressing into my spine and felt better only after I swigged a few mouthfuls.
How did I set my target? I used the MacMillan race predictor which gives a comprehensive race time prediction based on real previous performances. With that, I had a target and training pace to use.
3) Equipment
My trusty arm pouch is turning out to be much more of a pain than I anticipated. I'd say it was a minor contributor to my near crash of this event. Whilst the previous Nike ones were good by not giving abrasions, this current black kit repeatedly caused armpits abrasions. Need to seriously rethink how to carry gear/food on runs.
Bought a pair of technical running socks for the first time the week before the race. Ran a 6k in it and it felt really really good. Only problem, with it being so thin, there was too much room inside of my shoe. Too risky to do something new at this stage. So reverted to my trusty cotton socks. At about the 35k mark, the socks bunched up and caused a horrid foot pain, to add to everything else going on.
Had an interesting exchange with a fellow forumer on the use of cap/visor in this race. My conclusion? It is invaluable! Just as a comparison, I took off the cap for a short bit on the return leg and I thought the glare and heat was intolerable. Next stop, a proper running visor.
4) Nutrition
So fibre or no fibre the days before a run? I must vote to go with your normal diet, no matter what it is. I switched to low fibre and although there weren't major issues, I just never felt entirely comfortable with it. No bulk for stools on race morning, but had a sense of constipation. Not really troubling but I think I'd stick with usual fruit and veggies.
On race, I knew they had bananas at 35k, so I could afford to eat stuff at 15k and 25k. As it turned out, ended up taking an extra mini-Mars bars with me so downed a Mars bar at 8k as well. A little sticky but as the drink stations are well posted, strategy was to slow down a short distance from station, chomp down the bar and then wash down with fluids. This works for me and somehow seems more pleasurable than gulping gel.
5) Race ReportSee above
6) Learning points
a. Get technical running socks
b. Use a cap/visor
c. Start taper 16-19 days before, last LSD no closer than 19 days to event.
d. Arm pouch is a no-go
e. Don't compromise on walk-breaks early on
f. Fibre diet is ok pre-race
g. Does deep heat help?
Friday, November 9, 2007
NUS Hill Run
After a couple of half-starts, finally managed to complete a proper NUS Hill run this week. What a turn out it was, 11 runners in total. Finally go to put some faces to nicks. Was undertaking this with a no small amount of trepidation, as had crashed and burned the first time I took on the hills. Once again started out at a pace somewhat faster than I am comfortable with (thanks to xdd!). 5:20min/km, HR up to 160 already and barely 1km into the run. Chatted with DO at the beginning and soon came up to HPV. Really cool to get into the park, probably not been there in over 25years. No time for sightseeing though, hit the top of the hill and waited for the rest to catch up. Nice to have an early break, and mindful of Vigilante Drive to come. Down the back lane and out to Zehnder Road, everyone still going strong. Soon hit the foot of Vigi Drive, don't care how slow I look, I am JOGGING up this slope. Sure enough, soon left behind as everybody else charged up. Took my time to get to the top, but as I got there, felt relieved as I had got to the top in good shape and now I knew I was going to finish the run at least! Down the slope, into SP1 and water break. All the breaks are making this a very manageable run. Retrospectively this was really good interval training, sweat it up the slopes, then take ample rest, then repeat.
Ok, onwards. Up science park, chatted with Freddy. First time he was doing this route and he was enjoying it tremendously. Gave him some tips on the area and soon we were turning back down South Buona Vista road. Cutting across SBV back down to SP2 is a really hazardous exercise, can't see round the bend and who knows what crazies may be driving.
Cut a long story short, the group hung tight till we hit the base of PGP (near guild house) again. wend88 calls it a day on her first NUS Hill Run. She's done fantastically well keeping up with the pace up till now. I remember my first Hill Run when I walked the last 6km after trying to keep up with Ronnie and tktan inthe first 3. Last 5 km around NUS. Freddy, DR, Ronnie decide to attack the PGP hill with gusto. I am hanging back a little. Finally, into NUS, around UCC and the last 1km. Everybody SPEEDS up! Finally, guild house comes into sight. I've officially COMPLETED a NUS Hill Run. xdd, I want my cert.
Post run refreshments were great. Drinks and fruit, thanks tktan and BR.
As usual, scoot off for my meetings. Heard the guys enjoyed dinner. Hopefully I'll get a chance next time.
Some pics here --> tktan's, BR's
Till next week (or this week, actually)
Ok, onwards. Up science park, chatted with Freddy. First time he was doing this route and he was enjoying it tremendously. Gave him some tips on the area and soon we were turning back down South Buona Vista road. Cutting across SBV back down to SP2 is a really hazardous exercise, can't see round the bend and who knows what crazies may be driving.
Cut a long story short, the group hung tight till we hit the base of PGP (near guild house) again. wend88 calls it a day on her first NUS Hill Run. She's done fantastically well keeping up with the pace up till now. I remember my first Hill Run when I walked the last 6km after trying to keep up with Ronnie and tktan inthe first 3. Last 5 km around NUS. Freddy, DR, Ronnie decide to attack the PGP hill with gusto. I am hanging back a little. Finally, into NUS, around UCC and the last 1km. Everybody SPEEDS up! Finally, guild house comes into sight. I've officially COMPLETED a NUS Hill Run. xdd, I want my cert.
Post run refreshments were great. Drinks and fruit, thanks tktan and BR.
As usual, scoot off for my meetings. Heard the guys enjoyed dinner. Hopefully I'll get a chance next time.
Some pics here --> tktan's, BR's
Till next week (or this week, actually)
Wednesday, November 7, 2007
Salt Supplementation for Exercise and Training?
For some reason, exercise and training seem to attract a fair amount of myth and magic. Is salt supplemenation really needed for aerobic training? Lets find some evidence.
http://www.ajcn.org/cgi/reprint/72/2/564S
http://www.ultrunr.com/noakes.html
I quote;
Other electrolytes and minerals
Potassium is the major intracellular ion and is lost from the body in sweat and urine during exercise. However these losses are small (<1 gm even during very prolonged exercise) and are replaced by the normal daily dietary intake of 2-4 g. There is no evidence that potassium supplementation is required by the physically active.
Magnesium is another intracellular ion that, like potassium, is lost in sweat and urine during exercise. But the losses are trivial. There is no published evidence showing that magnesium deficiency is either common amongst the physically active, or that magnesium supplementation can either increase the intracellular magnesium stores, or enhance performance (15). The balance of evidence indicates that although body iron stores may be marginally reduced in some athletes, especially long distance runners, the incidence of true iron deficiency requiring treatment is no higher in the physically-active than in the sedentary population (16,17). Furthermore, the causes of iron deficiency anaemia in the physically active are not different from the causes of the condition present in sedentary persons. There is no indication for the indiscriminate use of iron supplementation by the physically active.
The intake of calcium especially by adolescent females, whether or not they are physically active, is usually less than the Recommended Daily Allowance (RDA). Hence adolescent female athletes come from a population that is already predisposed to an inadequate calcium intake. Female athletes in activities that favour thinness such as gymnastics, ballet dancing and running, are especially likely to eat kilojoule-restricted and therefore calcium-deficient diets. The chronic ingestion of a low calcium diet is associated with a reduced adult bone mass (18) and greater risk for the development of osteoporosis including the complications of fractures of the hip (19) or, in athletes, stress fractures (20). Hence there is a need to insure that females especially, ingest sufficient calcium throughout life.
There is no published evidence that the dietary requirements for chromium, copper, zinc or phosphate are increased in the physically active or that supplementation with any of these nutrients will improve athletic performance.
http://www.ajcn.org/cgi/reprint/72/2/564S
http://www.ultrunr.com/noakes.html
I quote;
Other electrolytes and minerals
Potassium is the major intracellular ion and is lost from the body in sweat and urine during exercise. However these losses are small (<1 gm even during very prolonged exercise) and are replaced by the normal daily dietary intake of 2-4 g. There is no evidence that potassium supplementation is required by the physically active.
Magnesium is another intracellular ion that, like potassium, is lost in sweat and urine during exercise. But the losses are trivial. There is no published evidence showing that magnesium deficiency is either common amongst the physically active, or that magnesium supplementation can either increase the intracellular magnesium stores, or enhance performance (15). The balance of evidence indicates that although body iron stores may be marginally reduced in some athletes, especially long distance runners, the incidence of true iron deficiency requiring treatment is no higher in the physically-active than in the sedentary population (16,17). Furthermore, the causes of iron deficiency anaemia in the physically active are not different from the causes of the condition present in sedentary persons. There is no indication for the indiscriminate use of iron supplementation by the physically active.
The intake of calcium especially by adolescent females, whether or not they are physically active, is usually less than the Recommended Daily Allowance (RDA). Hence adolescent female athletes come from a population that is already predisposed to an inadequate calcium intake. Female athletes in activities that favour thinness such as gymnastics, ballet dancing and running, are especially likely to eat kilojoule-restricted and therefore calcium-deficient diets. The chronic ingestion of a low calcium diet is associated with a reduced adult bone mass (18) and greater risk for the development of osteoporosis including the complications of fractures of the hip (19) or, in athletes, stress fractures (20). Hence there is a need to insure that females especially, ingest sufficient calcium throughout life.
There is no published evidence that the dietary requirements for chromium, copper, zinc or phosphate are increased in the physically active or that supplementation with any of these nutrients will improve athletic performance.
Thursday, November 1, 2007
Sub-2hr Marathon?
In the wake of HG's phenomenal run in Berlin, there was an interesting discussion in SG Runners on the possibility of a sub-2hr marathon in the future. I beleive that the time will be soon, due to the greater opportunities and technologies that now exist.
http://sgrunners.com/forum/index.php?showtopic=5858&st=30&p=194107&#entry194107
http://sgrunners.com/forum/index.php?showtopic=5858&st=30&p=194107&#entry194107
Glycerol Hyperhydration?
An interesting discussion on glycerol hyperhydration. Does it work?
-->http://www.ultrunr.com/glycerin.html
An excerpt;
I have read the postings on the glycerol issue with interest, and need to inform you of several facts.
I am one of the University of New Mexico scientists who first researched glycerol hyper hydration for improved exercise performance. Based on our and Bud Riedesel's findings (1987), the university invested in patent protection for using glycerol as a hyper hydration agent suitable for use during exercise. In 1996, the patent was purchased by InterNutria, a nutritional supplements company within the larger InterNueron Pharmaceutical Company. Thus, InterNutria has patent protection for using glycerol hyper hydration for enhancing exercise performance.
I am currently contracted by InterNutria to provide scientific advice and commentary on their glycerol product - "ProHydrator". ProHydrator was scheduled to be released to market this June, but the USOC ban on glycerol 'came out of the blue' and has delayed the product release. Such a delay was decided by the company due to the sponsorship of USA Triathlon, as well as several professional triathletes.
From my understanding, the USOC ban is based on glycerol being classified as a tissue dehydrator. Other tissue dehydrators are mannitol, sorbitol, and urea. Such substances are routinely used in clinical practice to dehydrate the brain and eye as a treatment for edemas resulting from a variety of clinical disorders. It just so happens that mannitol, sorbitol, and urea are also potent osmotic diuretics. Glycerol seems to have been included in the banned list of mannitol and sorbitol due to the potential for glycerol-induced diuresis.
I have recently written a major review of the clinical and applied uses of glycerol ingestion. It is currently in review. Within this manuscript is a section that pertains to glycerol-induced diuresis. It is important to remember that glycerol ingestion is not the same as glycerol hyper hydration. The latter involves the additional ingestion of 1-2 L of water. Simply ingesting a concentrated solution of glycerol will not hyper hydrate the body, but dramatically increase glycerol concentrations in the blood, interstitial fluid, and kidney filtrate. Increased urinary glycerol has the potential to increase urine flow due to retarding water reabsorption in the kidney. This is the mechanism of the diuresis from mannitol and sorbitol.
Glycerol does not cause a marked diuresis, however, because glycerol is still rapidly reabsorbed in the proximal and distal tubules. Mannitol and sorbitol are not. There is no evidence in the medical literature for a glycerol-induced diuresis. Nevertheless, anecdotal expressions of glycerol-induced diuresis occur in many manuscripts.
I have written a scientific reply to InterNutria for use in the company petitioning the USOC to remove the ban on glycerol.
It is ironic that glycerol has been used by the world's elite athletes for many years. Although it is easy to assay for urinary glycerol, and interpret data, I do not think the testing lab has or is currently performing the assay. It would be easy to detect exaggerated use of glycerol as the kidney can reabsorb almost all glycerol up to blood glycerol concentrations approximating 1.2 mmol/L. As resting blood glycerol approximates 0.05 mmol/L and may increase to 0.5 mmol/L during extreme prolonged exercise and carbohydrate depletion, the only way to cause glycerol to appear in the urine is to ingest large quantities. Thus, if the USOC wanted to, they could easily determine a urinary concentration indicating large amounts of glycerol ingestion. For your information, urinary glycerol can increase to above 20 mmol/L within 30 min after ingesting 1.2 g glycerol/kg body wt.
The USOC is not justified in the ban on glycerol for hyper hydration or proposed metabolic advantages to athletes. Hyper hydration is no worse than ingesting liquid carbohydrate or water during exercise. In addition, glycerol turnover data indicate that 60% of glycerol is converted to glucose in the liver and kidney, 30% is incorporated into glycolysis for oxidation, and the remainder is presumably involved in triacylglycerol metabolism.
It appears that the ban on glycerol is a mistake and should be reversed in the near future. Failure to reverse the ban will not only expose to elite athletes to continued high risks of heat injury, but potentially result in a series of law suits from athletes and nutritional companies against the USOC.
I hope these facts help you understand the glycerol saga !
Rob Robergs, Ph.D. Director: The Center For Exercise and Applied Human Physiology The University of New Mexico
-->http://www.ultrunr.com/glycerin.html
An excerpt;
I have read the postings on the glycerol issue with interest, and need to inform you of several facts.
I am one of the University of New Mexico scientists who first researched glycerol hyper hydration for improved exercise performance. Based on our and Bud Riedesel's findings (1987), the university invested in patent protection for using glycerol as a hyper hydration agent suitable for use during exercise. In 1996, the patent was purchased by InterNutria, a nutritional supplements company within the larger InterNueron Pharmaceutical Company. Thus, InterNutria has patent protection for using glycerol hyper hydration for enhancing exercise performance.
I am currently contracted by InterNutria to provide scientific advice and commentary on their glycerol product - "ProHydrator". ProHydrator was scheduled to be released to market this June, but the USOC ban on glycerol 'came out of the blue' and has delayed the product release. Such a delay was decided by the company due to the sponsorship of USA Triathlon, as well as several professional triathletes.
From my understanding, the USOC ban is based on glycerol being classified as a tissue dehydrator. Other tissue dehydrators are mannitol, sorbitol, and urea. Such substances are routinely used in clinical practice to dehydrate the brain and eye as a treatment for edemas resulting from a variety of clinical disorders. It just so happens that mannitol, sorbitol, and urea are also potent osmotic diuretics. Glycerol seems to have been included in the banned list of mannitol and sorbitol due to the potential for glycerol-induced diuresis.
I have recently written a major review of the clinical and applied uses of glycerol ingestion. It is currently in review. Within this manuscript is a section that pertains to glycerol-induced diuresis. It is important to remember that glycerol ingestion is not the same as glycerol hyper hydration. The latter involves the additional ingestion of 1-2 L of water. Simply ingesting a concentrated solution of glycerol will not hyper hydrate the body, but dramatically increase glycerol concentrations in the blood, interstitial fluid, and kidney filtrate. Increased urinary glycerol has the potential to increase urine flow due to retarding water reabsorption in the kidney. This is the mechanism of the diuresis from mannitol and sorbitol.
Glycerol does not cause a marked diuresis, however, because glycerol is still rapidly reabsorbed in the proximal and distal tubules. Mannitol and sorbitol are not. There is no evidence in the medical literature for a glycerol-induced diuresis. Nevertheless, anecdotal expressions of glycerol-induced diuresis occur in many manuscripts.
I have written a scientific reply to InterNutria for use in the company petitioning the USOC to remove the ban on glycerol.
It is ironic that glycerol has been used by the world's elite athletes for many years. Although it is easy to assay for urinary glycerol, and interpret data, I do not think the testing lab has or is currently performing the assay. It would be easy to detect exaggerated use of glycerol as the kidney can reabsorb almost all glycerol up to blood glycerol concentrations approximating 1.2 mmol/L. As resting blood glycerol approximates 0.05 mmol/L and may increase to 0.5 mmol/L during extreme prolonged exercise and carbohydrate depletion, the only way to cause glycerol to appear in the urine is to ingest large quantities. Thus, if the USOC wanted to, they could easily determine a urinary concentration indicating large amounts of glycerol ingestion. For your information, urinary glycerol can increase to above 20 mmol/L within 30 min after ingesting 1.2 g glycerol/kg body wt.
The USOC is not justified in the ban on glycerol for hyper hydration or proposed metabolic advantages to athletes. Hyper hydration is no worse than ingesting liquid carbohydrate or water during exercise. In addition, glycerol turnover data indicate that 60% of glycerol is converted to glucose in the liver and kidney, 30% is incorporated into glycolysis for oxidation, and the remainder is presumably involved in triacylglycerol metabolism.
It appears that the ban on glycerol is a mistake and should be reversed in the near future. Failure to reverse the ban will not only expose to elite athletes to continued high risks of heat injury, but potentially result in a series of law suits from athletes and nutritional companies against the USOC.
I hope these facts help you understand the glycerol saga !
Rob Robergs, Ph.D. Director: The Center For Exercise and Applied Human Physiology The University of New Mexico
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