bobmcgee

Durability …

I have a buddy who lives in Queensland. We had taken a little time off our regular careers to study something totally unrelated and met at Charles Sturt University. Roy and I have a lot in common including a passion for birds and live music. It was not in the least surprising that we enjoyed a yarn and a beer.

When I signed up to the cycling app Strava up popped Roy’s visage and we have followed and encouraged each other since. Roy has clocked up more than 35,000 km since he started using the app. I am most impressed.

It got me thinking about the sort of distance Grand Tour professionals accumulate over their careers. Or what about a single big year?

When Strava got started the bench mark to aim at belonged to Tommy Godwin a native of Stoke on Trent, UK and a professional cyclist. Back in 1939 he rode a staggering 120,805 km (75,065 miles) in a year. Since 100,000 miles was a good round number and not far off he carried on to nail that landmark in 500 days!

The record stood until 2016 when the American Kurt Searvogel edged him out with 122,432 km (76,076 miles). The Ultramarathon Cycling Association logged his efforts on its website and vouched for his achievement to the satisfaction of the Guiness Book of World Records. His Strava trophy case is stacked with badges although it seems that he is not currently active.

Nor is his record. That was eclipsed by another American, Amanda Coker, the very next year. She blew it away with 139,326 km (86,573 miles) about 382 km a day. By then she was in the groove so she took the opportunity to knock off Tommy’s 100,000 mile record in just 423 days.

Bird watchers like to go for a big year so what about a cycling big year? I think there is a great opportunity there for you Roy.

Glycogen Dethroned …?

A couple of weeks ago I wrote Running on Fat in which I said that glycogen was king. The current paradigm can be summed up as things go better with carbs. That is before during and after. Muscle glycogen depletion during exercise is the main factor in the onset of fatigue. If you want to exercise again in a hurry you need to get some carbs down in a hurry. The amount and type vary from paper to paper and there is an unresolved debate about the addition of protein. Overall though it is suggested that 6 to 12 grams of carbohydrate per kilogram within 30 minutes of completing an exhausting workout should have you ready to go again the next day.

Since my muscles are not being rewarded for their efforts with a jar of marmalade after every session I have been wondering how much of a disadvantage I’m putting them at. And it’s not that easy to find out.

Some short term research has been done putting normal (high carb) athletes on low carb diets for three weeks and watching their performance suffer. Hardly surprising that it goes down hill it takes a few weeks to sort out your fluid and electrolyte balance and adjust to ketosis.

The body can make it’s own glucose from fat and if it’s starving it can turn to protein. In the absence of ingested carbohydrate does glycogen replacement grind to a halt or does gluconeogenesis step into the breach?

I was pleased to come across a paper by Volek et al describing research with 20 well matched elite athletes 10 of whom were regular high carb guys and 10 were low carbers (and had been for at least 9 months). Naturally, when you get your hands on such a group, you take muscle biopsies and put them on a treadmill for three hours, take more muscle biopsies and measure everything you can think of. Then you give them two hours to recover before taking another muscle biopsy!

The rate of fat oxidation was two to three times higher in the low carb athletes and it peaked at a higher level of effort. Glycogen stores, usage and replacement were very much the same in both groups.

Their conclusion …

Compared to highly trained ultra-endurance athletes consuming an HC (High Carb) diet, long-term keto-adaptation results in extraordinarily high rates of fat oxidation, whereas muscle glycogen utilization and repletion patterns during and after a 3 hour run are similar.

At the ultra marathon level the benefits of using fat as fuel are appealing to more and more competitors, you just don’t run out.

Metabolic Goodness …

It was my long ride this morning. In fact my longest in this incarnation of my cycling career. 80 km. Thirty years ago I would have made sure I ate a good breakfast and would have taken a banana or two and some other snacks perhaps. This morning was devoid of breakfast and there were no snacks en route. I just took plenty of fat, all stored internally and it will be a long time before that runs out!

After my low carb lunch my ketones were ~6mm/litre. My fat cells are throwing ketones around like the missus spends my money, my muscle cells by comparison are as tight as Mr Scrooge. (Forgive me Gayle I know you are very sensible with our money and I’m the one that throws it around).

The reason that fat cells waste energy when ketones are present whilst muscle cells, including heart muscle, are very efficient are complex. Dr Bikman explains this as clearly as is humanly possible …

He has a book coming out in a few months entitled Why We Get Sick. Spoiler – it’s because of insulin resistance but it will be very interesting to read what he has to say about that and I expect it will be remarkably lucid.

Ketosis …

In my recent reading I came across a paper in the medical literature than mentioned ketosis and followed that in brackets with ketoacidosis as though the two were synonymous. How dumb is that I thought and moved on. Now I can’t find it again and dumb is not a useful search term – way too many results.

On a carb restricted diet the body produces a group of chemicals called ketones, hence the keto in keto diet. Ketones are excellent fuel for the brain and heart in the absence of normal amounts of glucose. Our ancestors went through lean times it was ketones that got them through. Nutritional ketosis is a normal response to fasting and carbohydrate restriction.

Ketoacidosis on the other hand is a medical emergency. It occurs mostly in people with type 1 diabetes mellitus. Ketones are present at more than ten times the quantity found in dietary ketosis along with very high blood sugar. The combination causes a pH change in the blood which will bring liver and kidney function into a downward spiral. This is sometimes the way that diabetics first present and remains a risk if patients fail to manage their insulin properly or hit the booze. Death is the likely outcome in the absence of prompt treatment.

Type 1 diabetes occurs because the islet cells in the pancreas that make insulin are snuffed out by the body’s own antibodies. If there are still some functional islet cells ketoacidosis is less likely.

What stops the enthusiastic keto dieter from slipping into ketoacidosis? Two things. On a low carb diet blood sugar is not through the roof. Secondly functional islet cells mean that insulin is available when needed. Insulin doesn’t only regulate glucose it can also turn down the production of ketones. Ketosis is a normal functional response so it is hardly surprising that it is well regulated.

My low carb diet is rolling along quite nicely. A reduction of five inches off my circumference is evidence enough that I am maintaining an effective level of ketosis but it is easy to check. Ketones can be measured in blood, breath or urine. There is a good article on the available technologies at Diet Doctor. Given that I have no interest in checking every day for the rest of my life I opted for the low tech urine sticks. The brand available at the local pharmacy is Keto-Diastix which measures glucose and ketones and gives a numerical result. I am pleased to say that glucose has been absent from my urine, as it should be, whilst ketones have ranged from 1.5 to 4.0 mm/litre.

I have departed the ranks of the obese and I am now proudly overweight!

Stretch …

This article does not concern itself with my impact on Lycra. The world is not yet ready for that experience, getting there though. No, today’s analysis concerns the enormous benefit the cyclist can expect from stretching.

Athletes stretch for a number of reasons principally

to enhance athletic performance
prevent injury
prevent muscle soreness
improve flexibility

Let’s deal with the last first because this is purely an opinion. If you search for bike fit on Youtube you will be able to occupy hours of your time, hear the word flexibility frequently, learn the importance of a professional bike fit and learn virtually nothing about how to do it for yourself.

How much flexibility does a cyclist need? If you can bend at the waist, stretch your arms out in front and send your feet once round the pedals you’ve got it. What’s more repeating it will not increase it. Strength and stamina will help you keep at it longer but that comes from training not stretching.

So flexibility is not high on my list of concerns but I would definitely like to perform better whilst avoiding injury and muscle soreness.

Esposito and Limonta investigated the effect of passive stretching on performance. Nine males exercised at 85% of VO2max until exhaustion with and without pre-exercise stretching. A good stretch prior to exercise decreased endurance by 26%, increased the oxygen needed by 4% and decreased efficiency by 4%. No, I haven’t reported the results round the wrong way …

These results are suggestive of an impairment in cycling efficiency due to changes in muscle neural activation and viscoelastic characteristics induced by stretching.

It’s not an isolated finding. Here’s another Wilson et al. It also goes for sprinting but here’s some good news – dynamic stretching doesn’t hinder athletic performance as much!

It might be worth sacrificing some performance for insurance against injury. Pope et al …

investigated the effect of muscle stretching during warm-up on the risk of exercise-related injury. 1538 male army recruits were randomly allocated to stretch or control groups. During the ensuing 12 wk of training, both groups performed active warm-up exercises before physical training sessions. In addition, the stretch group performed one 20-s static stretch under supervision for each of six major leg muscle groups during every warm-up. The control group did not stretch.

The protective benefit? Nil.

Muscle soreness has been investigated sufficiently often for there to be a Cochrane meta-analysis on the subject. Twelve studies including over 12,000 participants were included in the review. The conclusions …

The evidence from randomised studies suggests that muscle stretching, whether conducted before, after, or before and after exercise, does not produce clinically important reductions in delayed‐onset muscle soreness in healthy adults.

So there you have it. If you see people stretching before your next race or charity ride give them a a few words of encouragement and a big smile.

Volume vs Intensity …

Cycling does you good. Does more cycling do you even more good?

Given my advanced age the effect of cycling on all cause mortality is of urgent concern. Research on older folk getting off the couch and onto their bikes is scant. The obvious advantage of such studies would be the relatively short time the researchers would need to wait for the endpoints. In the absence of old folk as guinea pigs we can look to wise coaches for opinion or extrapolate from studies that draw their participants from a wider spectrum.

Joe Friel is wise and famous and a prolific author. In Fast After Fifty he tells us that long slow distance will set you apart from the guy next door. It will also set you apart from the guys on the podium. In other words he damns it with faint praise. His prescription is to go for the intensity.

This is borne out by findings from the Copenhagen City Heart Study (Schnohr et al)

Relative intensity and duration of cycling were recorded in 5106 apparently healthy men and women aged 21-90 years drawn from the general population of Copenhagen, and followed for an average of 18 years. Total number of deaths during follow-up was 1172, of these 146 were coronary heart disease deaths. For both sexes we found a significant inverse association between cycling intensity and risk of all-cause and coronary heart disease death, but only a weak association with cycling duration.

If you want to live longer ride faster not further. QED.

Charity rides are a fun way to spice up your riding program. They’re better than races because they are races really but a large proportion of the riders don’t realise it and are therefore easier to beat. These events have succumbed to the Corona virus for the moment but they will return one day. The one I’m looking forward to is Maryborough’s R3R. I did the short course last time. Next time my goal is the full 109 km.

Can I prepare for 109 km by doing interval sprints? Well not on their own. Volume is vital, the effort though must be at a certain intensity. The “fat burn” zone doesn’t cut it. Joe again …

Very low heart rate training is often referred to as the “fat-burning” zone. This is another case of a myth that refuses to go away. Low intensity, slow exercise does not burn more calories or more fat than does high-intensity, fast paced exercise.

In fact high intensity exercise will have a greater impact on body fat than low intensity junk miles even if the calories consumed during the exercise is less because of the impact on metabolic rate during the rest of the day.

Which leads us to the real point. Volume is a fairly meaningless metric. What matters is effort versus recovery, training versus over-training.

Salt …

It’s been traded, taxed, fought over. It’s been ploughed into the fields of defeated city states. It is used in some religious ceremonies. It is essential to life and one of the fundamental tastes mediated by the human tongue. It’s the difference between a herring and a kipper, pork and bacon because it is an effective preservative. It has been used as currency and it gives us the word salary (although the Roman Army was never paid in salt).

Solntsata in Bulgaria was possibly the first city in Europe. The name translates as salt works and they have been in use since 5400 BC. There is evidence of even older salt extraction processes in China.

Cheetham Saltworks, Victoria

It is essential to our physiology, without it we couldn’t even generate a nerve impulse. But In excess it increases blood pressure which in turn increases the risk of heart disease and stroke. So how much is the right much?

The Australian guidelines are formulated by the National Health and Medical Research Council and can be accessed at this government website which also sets out the logic behind the recommendations. They deal in milligrams of sodium. Salt is sodium chloride. 1 unit of sodium = approximately 2.5 units of salt once you add the chloride.

The suggested daily target is 2 grams of sodium a day for adults (roughly 5 grams of salt). The NH&MRC wrestled with an upper limit but concluded that

… because the relationship between sodium intake and blood pressure is progressive and continuous, it is difficult to set a UL precisely.

So no upper limit was set.

The average Australian is ingesting about 9 grams of salt a day currently. Some is an inescapable part of the raw ingredients of our diet but much of that figure is added to restaurant and take away food, processed and packaged food, and drinks such as Coca Cola and sports drinks. It makes food more palatable by dialing down the sensations of bitterness and over sweetness. In the case of drinks it increases thirst – how convenient for the manufacturers.

So far as it goes the NH&MRC guideline purports to have an evidence base, is easy to understand and is aimed at getting the community’s blood pressure down.

The low carb intelligentsia seem to give the issue very little concern. How come?

A low carb diet has a real food base. McDonalds is out. Most packaged foods are out. If you start with the raw ingredients of a keto diet the challenge is to get enough salt especially if you are also into sweaty exercise.

The phrase lower limit doesn’t occur in the government website. Whilst the essential nature of salt is acknowledged the assumption seems to be that less is best. There is evidence to the contrary.

An article by Mente and an insane number of other authors (28 other authors – I imagine they wrote every 29th word and then had a committee meeting on where to put the punctuation marks) )from the Lancet May 2016 entitled Associations of urinary sodium excretion with cardiovascular events in individuals with and without hypertension: A pooled analysis of data from four studies, reports on a study of 133,118 individuals roughly half of whom were hypertensive. The daily intake of salt was compared to the likelihood of death and major cardiovascular events and blood pressure over a median period of 4.2 years.

Compared with moderate sodium intake, high sodium intake is associated with an increased risk of cardiovascular events and death in hypertensive populations (no association in normotensive population), while the association of low sodium intake with increased risk of cardiovascular events and death is observed in those with or without hypertension.

There is a subtlety there that I will return to but first let’s take a look at the results as a graph …

On the vertical axis we have the hazard ratio, on the horizontal axis the daily excretion of sodium in mg. Daily excretion of sodium is pretty much the same thing as daily intake of sodium. The amount of sodium in blood is regulated by the kidneys and there is no storage mechanism. The U-shaped curve comes as no surprise, sodium is essential therefore as you reduce the intake you’d expect to reach a point where risk starts to increase. Excretion of less than 3g of sodium a day increases the risk of cardiovascular catastrophes and death. The graph shows that the risk increases above 7g a day. The lowest point of the curve falls between 4000 mg and 6000mg of sodium or ~11 grams of salt.

If instead of looking at the whole cohort we look at the hypertensive and normotensive subgroups steepness to the left of the low point stays the same for both but to the right it rises more steeply for those with high blood pressure. Why should this be?

The kidneys play a pivotal role in the maintenance of blood pressure and not all kidneys are equal. Researchers have bred salt sensitive rats that develop high blood pressure. If their kidneys are transplanted into normal rats the recipients develop high blood pressure on a high sodium diet. Normal rats receiving kidneys from normal rats do far better. The problem follows the kidney. This is borne out in human transplantation as well. If the donor has a family history of hypertension the recipient has a ten fold increased risk of developing hypertension.

Mente et al looks like a pretty robust study. If we accept their findings it follows that –

The Australian public are not far from an ideal salt intake.
The NH&MRC guidelines are set at a level which will increase risk.
and unless you have hypertension there are more important things to think about.

If only things were that easy. Not all studies bear this out. Cook et al …

found an increased risk at high sodium intake and a direct relation with total mortality even at the lowest levels of sodium intake.

They suggest that other studies are in error …

While several studies suggest beneficial effects of lower sodium on cardiovascular disease, the relationship with total mortality remains controversial. Some have reported a J-shaped curve, but this may be due to poor quality measurement of sodium or confounding bias.

Clearly the definitive answer still eludes us although I am suspicious of any study of an essential nutrient that doesn’t find detriment at a low level of intake.

Which study do we choose to ignore?

I think the best strategy is to ignore neither despite their contradiction. Rather we should take our blood pressure. It’s easily done at home. The hypothetical guy I studied in Physiology weighed 74kg had a pulse rate of 72 and a BP of 120/80. Blood pressure tends to rise through life and the doctor tends to reach for his prescription pad at about 140/90. If you’re border line and want to stave off the pills there are some non-drug remedies to consider …

Lose weight
Exercise
Reduce your salt intake

If you’ve got it to lose then 10 kg off should drop your BP by about 10 mm of mercury. For each gram reduction of salt a hypertensive person can hope to drop about 2 mm of mercury.

Cycling Science …

I have been amusing myself by dipping into Cycling Science a neat little book by Max Glaskin, published by Ivy Press. It’s pitched at the interested reader but you don’t need a science degree to read it and the style is quite light …

There are hundreds of parts on a bicycle … Without doubt the most important part is the frame, often described as the heart of the bicycle by people whose grasp of anatomy should disqualify them from medical practice.

Yes, it’s the skeleton, of course.

Chapter 5 is on aerodynamics, such an important part of cycling that it repays any cyclist handsomely for the trouble of reading it. And it contains this welcome boost to my ego …

The graphic concerns the part that aerodynamics played in Chris Boardman’s one hour record (56.375 km or 35.03 miles) set in 1996. At this scale reading the print is a bit difficult but don’t hold that against the book. It is nicely illustrated. The gist of it is that Boardman adopted the superman position and reaped the benefits of reduced drag . Each line above that indicates how far he would have traveled in other positions. On a sit up and beg bike like my mountain bike (top line) he would have covered a mere 14.893 km. Well Mr Boardman you’re not superman at all – I can cover 25 km.

Returning to reality I suspect that Boardman could beat me on an icecream seller’s tricycle and that the calculations are a little astray in this particular figure.

A good addition to any cycling tragic’s library.

Oh Shit …

The ultimate coprolite was found in 1972 during excavation at a Viking settlement at Jorvik, now York. It Is possibly the largest example of fossilised human feces ever found, measuring 20 centimetres (8 in) long and 5 centimetres (2 in) wide. Analysis has revealed that its producer subsisted largely on meat and bread whilst the presence of several hundred parasitic eggs suggests they were afflicted with intestinal worms.

“This is the most exciting piece of excrement I’ve ever seen… In its own way, it’s as irreplaceable as the Crown Jewels”.

Dr Andrew Jones, paleoscatologist.

Not to be confused with a coprolite a coprolith is a mass of hard fecal matter in the colon, the end result of severe constipation.

The York coprolite was dropped whilst being handled. It broke into three pieces. It is quite likely that the butter fingers that did that to the crown jewel of turds said, “Oh shit”. Which is very much what I was saying at three o’clock this morning during the fourth attempt to eject a worthy replacement. It felt just as big and hard enough to be a fossil.

Constipation is a frequent complaint of those who have recently begun a low carb diet. I have heard it suggested that it’s not real – it’s just that there is now no need for a bowel movement every day and the problem is trying to pass something that just isn’t there. Believe me there was something there. Those that allow the possibility that it’s real suggest that it’s due to dehydration or a lack of salt. So keep up your salt and water intake.

Just as you struggle to disobey the first commandment, “Thou shalt not eat saturated fat” you bump into two more issues that the low carb proponents are heretical about – adding salt and a very mixed message regarding fibre. It was a bit late I felt for salt and water or even fibre to be of any use. Before going to bed I was thinking a few pints of Newcastle Brown Ale would be better but since beer is out I settled for half a bottle of red.

The scientific literature regarding nutrition is a mess but I must put in some time on salt and on fibre before I decide where I will be going on those issues. Here’s a quite entertaining lecture in the meantime …

Perhaps it was the red wine or maybe it was sheer determination but ultimately I was successful. I packaged it up and posted it York.

William Banting …

Good old King George lll died at Windsor Castle at 8.38 pm on the 29th of January, 1820. He’d been completely out of his mind for about a decade. He was buried in St Georges Chapel in the castle on the 16th of February. The undertaker was 5 feet 5 inches tall and about 5 feet 5 inches round.

These are the sort of details you have come to expect of McGee, though I confess that I made up the last one although it might have been close to the mark.

The undertaker in question was William Banting (1796 – 1878). He was much troubled by his weight, in 1863 he wrote …

Few men have led a more active life—bodily or mentally—from a constitutional anxiety for regularity, precision, and order, during fifty years business career, from which I have now retired, so that my corpulence and subsequent obesity was not through neglect of necessary bodily activity, nor from excessive eating, drinking, or self-indulgence of any kind, except that I partook of the simple aliments of bread, milk, butter, beer, sugar, and potatoes more freely than my aged nature required …

He had tried diet and exercise and a number of treatments we would find odd today such as taking the waters at various spas. At one stage of his life he was rowing a boat on the Thames every day before work but it made him so hungry it was doing more harm than good. Eminent doctors were consulted but to no avail.

Obesity seems to me very little understood or properly appreciated by the faculty and the public generally, or the former would long ere this have hit upon the cause for so lamentable a disease, and applied effective remedies, whilst the latter would have spared their injudicious indulgence in remarks and sneers, frequently painful in society, and which, even on the strongest mind, have an unhappy tendency …

Not a lot’s changed really.

Enter Dr William Harvey of Soho Square who prescribed a diet …

The items from which I was advised to abstain as much as possible were : —Bread, butter, milk, sugar, beer, and potatoes

By the time William was ready for bed he’d eaten about a pound (0.5 kg) of various dead animals, one serve of vegetables other than potato and a couple of ounces of dry toast. He’d drunk unlimited quantities of tea with no milk or sugar, half a dozen glasses of claret and a brandy, the first known keto diet published in the English language.

He tells us that he was 5 feet 5 inches tall and weighed 202 pounds (BMI 33.6). The weight and the girth dropped off. The undertaker to royalty was delighted …

I have not felt so well as now for the last twenty years.

Have suffered no inconvenience whatever in the probational remedy.

Am reduced many inches in bulk, and 35 lbs. in weight in thirty-eight weeks.

Come down stairs forward naturally, with perfect ease.

Go up stairs and take ordinary exercise freely, without the slightest inconvenience.

Can perform every necessary office for myself.

He tossed an extra fifty quid in the direction of Dr Harvey to use for the benefit of various hospitals and wrote and published a pamphlet, distributed free of charge so that others might share the benefits.

The Letter on Corpulence, Addressed to the Public ran into several editions and can still be downloaded. Subsequent editions were updated with further weight loss, reaching 46 pounds from a starting point of 202. He lost a little over 12 inches from his waist. (BMI 26).

I put on my former clothing, over what I now wear, which was a thoroughly convincing proof of the remarkable change. These important desiderata have been attained by the most easy and comfortable means, with but little medicine, and almost entirely by a system of diet that formerly I should have thought dangerously generous.