"The Experiment" Part 2

Now that you’ve heard my little diatribe in part 1 of "The Experiment", it’s time to turn to the game plan. Any half-witted coach will tell you that you need a goal prior to the commencement of any training regimen. Since bikini season is approaching, one would speculate that I’d be looking to lean down and muscle up in an effort to impress anyone who's easily impressed by a big hairy greased up dude in a speedo. Although not totally impossible, this is a slightly daunting task when considering that I cannot tell my body that I want to get my guns bigger while getting rid of my love handles and expect it to arbitrarily do this. Consider that (a) my body doesn’t really talk or listenb and does not have a conscience and (b) it take approximately a 2500kcal (calorie) surplus to gain a pound of muscle and a 3500kcal deficit to lose a pound of fat. Certainly, these are two very conflicting points and unless you’re a beginner to training or you’ve contacted your local black market pharmacist, the concomitant decrease of fat and increase of muscle is rather implausible.



So, what are my goals? I could easily just look back to some embarrassing moments in my life which revolved around body weight and attempt to avoid them again. One such wonderful example was when I was attempting to scare my friends at a cottage by putting on a novelty adult g-string in the form of a friendly monkey. At 320lbs this comedy soon became a tragedy as it snapped with great fury leaving me with few options for undergarments (ALWAYS have a backup plan). Rather than focusing on vanity however, I’m going to try something that seems novel and unique in fitness and is blatantly subjective; I’m going to train with the aim of feeling better about myself and staying healthy in an attempt to stave off diabetes and cardiovascular related disorders. By virtue of hard work, I’ll get stronger in addition to looking and feeling better about myself. As a trainer, I think this is an often overlooked concept and I have noticed that a greater reliance on metrics results in lower exercise retention. It’s important to set measurable goals (which I do have, but they’re really nothing that needs to be shared in this blog), but it’s equally important to emphasize that these goals should focus on improving oneself outside of the mirror. That being said, I still want to kick my own ass because I enjoy the feeling of giving it my best regardless of the outcome, so here’s my plan in addition to some fun practical applications of bioenergetics!



TRAINING

Since I've been training for hammer throw for 4 years now, I'm going to continue to do so but with some fun little modifications. As stated before, I'll be lifting and doing some hammer related training at PhysXtreme where I work out of (it's essentially the opposite of gyms like these). Here are some videos from the archive to give people an idea of what exactly hammer throw is since the typical initial reaction I get is one of blank stares with a concomitant response of "You throw hammers at people?"

This is me performing hammer throw:


This is also me performing hammer throw:



This is NOT hammer throw:

Without going into much detail because I think advertising my training protocol is sort of lame, I'm essentially going to be combining my throwing and lifting together. I'm focusing on more sport specific training which essentially means I try to lift heavy weights using as many muscles as possible, especially the muscles that will help me spin around in circles quickly and throw a metal ball with a wire attached to it as far as I can. I'll also blast my guns (biceps and triceps) periodically in an effort to keep myself impressed in the mirror.


Essentially, based on some of the pointers from my coach in the past, I'm going to do throws or turns in between exercises. It's a little different than what most people do in the gym but fundamentally I'm lifting weights, working hard and sweating. That should burn a few calories here and there.



NUTRITION

A key aspect to losing weight is nutrition. I often have to remind my clients that I only see them an hour out of the day and I can't control what they ingest the other 23hours. The problem with most diets is that they have a beginning and an end, and as I've discussed in the previous post, the yo-yo dieting ends up placing the individual in a worse situation than when they started. Without going off on a tangent too much (I'll save it for a different blog), this may be a result of evolution. Scientists are now looking at obesity as a function of survival through famine, which may have been an important selective pressure throughout human existence (4, 5). In this case, it's important to change the eating habits and behaviour rather than just making drastic and finite changes. It also doesn't hurt that members at our gym get some pretty nice discounts off of supplements from Hyperforme Nutrition.



I've also found that simplicity is best in terms of recommending nutritional changes. I've taken a liking to Dr. John Berardi's '7 rules of Good Nutrition ' and I'm going to regurgitate it here as well as add in my own little spiel underneath each rule discussing its validity and application:



1. Eat every 2-3 hours, no matter what. You should eat between 5-8 meals per day.

Generally speaking, eating every 2-3 hours won't necessarily boost the metabolism (I cringe at that idea in fitness as someone in the sciences and research of metabolism). Furthermore, it's been postulated that eating more frequently will generate greater fat loss by not only augmenting metabolism (ugggh) but also decreasing appetite and increasing fat loss. Work from  J. Cameron et al in own laboratory, The Behavioural and Metabolic Research Unit has indicated that this doesn't seem to be the case. With a consistent calorie deficit, there were no differences between those that ate 3 times per day and those that ate 6 times per day when body fat decreases and appetite were compared (measured objectively through gut peptides that regulate appetite as well as subjectively with questionnaires) (3). Personally, the only reason I would have smaller meals throughout the day is because it forces me to control my portions as I have an uncanny ability to eat an insurmountable quantity of food in one sitting. Have you ever been kicked out of a buffet or suffered from the 'meat sweats' as a result of competitive eating? Welcome to my world.

J. Cameron et al after a hard day of scientific networking in Amsterdam, pondering whether to order a small meal and eat more, or just gorge on a massive Dutch plate.

2. Eat complete (containing all the essential amino acids), lean protein with each meal.

There has been evidence to indicate that individuals who used high protein diets lost around twice as much fat as those in high carbohydrate diets even when no energy restriction was imposed (6). Proteins also have the highest thermic effect of feeding (TEF) and highest rating of satiety. In a nutshell, this means that an individual will burn more calories digesting protein in comparison to carbohydrates and fat, and furthermore they will feel more full if they have more protein in their meal.

3. Eat fruits and/or vegetables with each food meal.

Pretty self-explanatory. Fiber helps you stay regular and fiber will also increase the feeling of fullness in a given meal- pretty awesome for a substance that doesn't even get absorbed into the body to be stored as fat. Fruits and veggies are a great source of fiber and vitamins so after all that complaining, your parents were right about something although I still disagree with my Euro family about the coolness of Speedos.

4. Ensure that your carbohydrate intake comes from fruits and vegetables. Exception: workout and post-workout drinks and meals.
Avoiding starchy foods which especially those that are fried and leached of all of their nutrientsis is never a horrible idea in our diabetic and 'obesogenic' North American society . There has been a steady increase in the popularity of multi-grain and whole wheat products which are in fact full of fiber and nutrients. However, there is still so much garbage in a lot of breads and cereals that you may just be better off avoiding them all together and substituting them with veggies, fruits and maybe basic oats and grains (azodicarbonamidec, calcium propionate and sulphur dioxide; what ever happened to mixing some yeast, flower and eggs?!).

Bread can be evil.

Now, there is the exception that workout and post-workout nutrition does not have to encompass fruits and vegetables. This is where we start to manipulate insulin a little bit. In the world of weight loss and weight gain, insulin can be one of the great allies or an even greater foe. Consider the following graph (don't fret!).

To simplify it, with some exceptions, glucose needs insulin in order to get into the cell (in this case, we'll refer to muscle). Think of insulin as that person that can get you (glucose) into the bar (muscle) without having to wait in line or pay cover. Insulin does this because it knows the manager of the bar(Glut-4) and calls them whenever you're too cheap or impatient to pay cover or wait in line. Glut-4 comes to the front door and tells everyone that you're cool, so you can come in and party because your friends have been dancing all night (muscle contractions) and are in need of some more energy (glucose!). On a side note, this is what goes through your brain when you work at bars and nightclubs in order to pay tuition.

So why is this workout and post-workout drink so important? Basically, during and after exercise the muscles are depleted of energy (derived from the breakdown of glycogen aka stored glucose in muscle). As a result, the muscles are more sensitive to insulin. Going back to the bar reference, you could say that the bar is empty and they are desperate to get people in. The workout shake replenishes this depletion and as a bonus keeps blood sugar levels relatively stable. I've tested my blood sugar after training using one of these shakes and it was an ideal reading.

The shake also includes protein which helps repair damaged muscle. Furthermore, protein and glucose act more effectively in synergy. finally, the added bonus of the 'meal' coming in liquid form is that it has faster gastric emptying which is just a fancy way of saying it gets digested more quickly and enters the blood faster in order to do the job it's supposed to do. The fact that muscle insulin sensitivity is high also means that the glucose is less likely to be stored in fat. This response is high about 45 minutes after training and tapers down thereafter, which is why the second shake should be consumed immediately after. Who would have thought that a sugar drink with some protein powder could have so many benefits? Well, apparently researchers at the University of Bath in England weren't so convinced, and there now seems to be some questions as to whether a protein drink is actually beneficial for athletes during training. Check out the press release. What it doesn't tell you is that they haven't performed research on it quite yet themselves, but rather conducted a review of all the research in the past. It usually leads the way for a thorough study to be conducted to try and put the final nail in the coffin on the issue. Sounds like sports performance research funding in England has suddenly increased, a function likely London 2012.

He should have had some proper workout nutrition.

5. Ensure that 25-35% of your energy intake comes from fat, with your fat intake split equally between saturates (e.g. animal fat), monounsaturates (e.g., olive oil), and polyunsaturates (e.g. flax oil, salmon oil).
Contrary to popular belief, there is no such thing as 'bad fats' and this belief is merely a result of uninformed people being given painfully brief summaries on selected scientific reports. The benefits of monounsaturates and polyunsaturates are constantly being touted (brain function, improved cardiovascular profile etc) so I think it would be redundant of me to list them here. The real problem is that people will avoid cholesterols for fear of the possible negative (and inconclusive) repercussions. Fundamentally, cholesterols and saturated/animal fats are necessary for normal hormonal functions. If cholesterol was really that bad for us then hormones such as estrogen and testosterone as well as cell membranes wouldn't exist in our bodies! Cholesterol is necessary for regular hormonal functioning, but like ANYTHING else, there is a threshold to the benefits before it may cause more harm than good. Realistically, if anyone is consuming excess amounts of cholesterol, they typically don't have a healthy lifestyle and these confounding factors have lead many to draw irrational conclusions. Even the current fad of bashing trans-fats isn't fully justifiable. Research has indicated that consumption of natural trans fats from milks and animal meat can actually do more good than harm in the fight to prevent metabolic disorders (7).

Warning: Buying foods that make health claims based on hysteria will not result in you being any healthier. Seriously though, did you really think that buying a bag of chips was going to be a healthy option?

6. Drink only non-calorie containing beverages, the best choices being water and green tea.
This is always an easy way to eliminate calories and diabetes-causing agents from your diet. I also prefer coffee since I drink mine black. Orange juice might seem like a healthy idea, but even 2 cups of the PC Blue Menu OJ will end up being around 240 calories and 44 grams of sugar.


7. Eat mostly whole foods (except workout and post-workout drinks).
If you're not convinced, try consuming nothing but protein shakes all day. You'll find that you change your mind quickly when your social life goes down the drain as a result of gastrointestinal distress.

Dr. Berardi also sticks to the 90% rule, which essentially means that if you follow these rules 90% of the time, the other 10% won't make a big difference and will also let you keep your mental sanity. So, if you're eating 40 meals/week, 4 of those meals don't necessarily have to adhere to the rules.



BIKING

One of the few things about living in the capital city is that it's pleasantly accessible to cyclists. Although there are some sketchy routes and the usual band of terrible drivers, I'm still thankful it's not as bad as this. With the combination of my personal efforts to do my part in attenuating climate change in addition to fighting the size of my adipocytes, I've found a great form of transportation (chaffing aside). In fact, on average I'll be biking around 85km/ week. With gas prices being brutal I thought that it might be appropriate to compare biking against my 2004 Corolla (a no-frills car that sports wonderful features such as a fuel efficient engine roughly the size of a lawn mower and manual windows). First thing is first, I need to roughly determine the amount of fuel my own body has which involves some physiological assumptions.



Here are some basic concepts before I start:

Fig 1.Step 1: You eat.
Step 2: Food breaks down, glucose goes into the blood.
Step 3: Glucose gets stored in the body in different forms. It's like a Transformer that you eat. Weird comparison, I know, but Transformers are awesome. Thanks to Dr. Pascal Imbeault for this pretty diagram and as well for passing me in his Exercise Physiology II class.

ATP (adenosine triphosphate) = the fundamental substance of energy in our muscles. Simply put, it receives energy and can give off that energy. This is important as the energy that it gives off is responsible for virtually all of the functions in our body (i.e. muscle contraction).


Glucose = A simple sugar that we get from foods. It gets broken down through a series of steps not worth mentioning here because most of you aren't that into the exciting world of biochemistry. The final product is ATP. BOOM! Energy. If it's not broken down, then it's stored in the form of glycogen. The presence of glucose in adipose tissue (fat) stimulates fat synthesis (tirglycerides, see Fig. 1). Twix + Skittles + sitting and playing video games = fat synthesis. Science.



So, with that out of the way, I can start calculating how much energy I have in my body using the following numbers:



Liver glycogen: 4.2g/100g fresh tissue (liver is ~ 1.5kg). The liver is 'pound for pound' the most glycogen dense part of the body so stop trashing the poor thing with so much alcohol!

Muscle glycogen: 1.6-2.1g/100g fresh tissue



The easiest way to figure out how much energy I'm going to get out of the glucose derived from glycogen (because remember, glycogen is the stored form of glucose) is by converting it into calories (kcal). We know that for glucose, it's roughly 4 kcal/g. Now that we've gotten most of the 'carb' energy out of the way, we also need to remember that we can break down fat and muscle proteins for energy as well. Here is the breakdown of how much energy we can get from muscle and fat in the body:



Muscle protein: 4.2 kcal/g

Fat: 9.5 kcal/g



Okay, you're probably falling asleep on me here, so I'll get to the point. I'll spare you the calculations for the sake of both your time and my embarrassment and just say that I have approximately 628 278 kcal to use in my body! WOW! That's like all-you-can-eat buffet for a week for me. Biking at 17km/h resulted in me burning approximately 690 kcal in one hour calculated through basic indirect calorimetry, which is a fancy way of saying that we can figure out how many calories you burn by measuring your breathing. If I was to bike to ‘empty’ I could bike for 910 hours and cover a distance of 15 470km which means that I can essentially take the scenic route from Ottawa to Charlotte North Carolina on one tank of gas!



Filling up my Toyota Corolla costs about $50 now for around 500km if I do primarily highway driving and buy the cheapest form of gas. That’s over 30 fill ups or $1500 for a trip straight to Charlotte. Buying the equivalent of 628 000 kcal of sugar ($3 for a kg) would cost me about $450. Win bike (This is all assuming that my pancreas doesn’t decide to call it quits halfway through the trip forcing me to buy Metformin or insulin which, if I’m in the U.S. and uninsured, would probably cost me the price of a new car).

GOALS
As I mentioned in the previous posting, I don't really have any major goals short of feeling better. Although, now that I think of it, losing ~10cm off my waist line and maybe around 4.5-6.5kg wouldn't hurt my chances at living longer and healthier. If that fails, I COULD always opt for surgery.

Stay tuned for results, assuming something actually happens. 


In the mean time, I'll be blogging less about myself and a lot more on more interesting topics like weight loss surgery, physical activity vs. diet, nutrition, weight loss supplementation, human metabolism and one of my personal favourites, the evolutionary origins of our weight gain!





REFERENCES

1. Ainsworth, B. E., Haskell, W. L., Herrmann, S. D., Meckes, N., Bassett, D. R., Jr., Tudor-Locke, C., et al. 2011 Compendium of Physical Activities: A Second Update of Codes and MET Values. Med Sci Sports Exerc.

2. Brooks, G. A., Fahey, T.D., Baldwin, K.M. (2005). Exercise Physiology (4th ed.). New York: McGraw-Hill.

3. Cameron, J. D., Cyr, M. J., & Doucet, E. Increased meal frequency does not promote greater weight loss in subjects who were prescribed an 8-week equi-energetic energy-restricted diet. Br J Nutr, 103(8), 1098-1101.

4. Prentice, A. M. (2005). Starvation in humans: evolutionary background and contemporary implications. Mech Ageing Dev, 126(9), 976-981.

5. Prentice, A. M., Hennig, B. J., & Fulford, A. J. (2008). Evolutionary origins of the obesity epidemic: natural selection of thrifty genes or genetic drift following predation release? Int J Obes (Lond), 32(11), 1607-1610.

6. Skov, A. R., Toubro, S., Ronn, B., Holm, L., & Astrup, A. (1999). Randomized trial on protein vs   carbohydrate in ad libitum fat reduced diet for the treatment of obesity. Int J Obes Relat Metab Disord, 23(5), 528-536.

 7. Ye Wang, M. Miriam Jacome-Sosa, Donna F. Vine, Spencer D. Proctor (2010) Beneficial effects of vaccenic acid on postprandial lipid metabolism dyslipidemia: Impact of natural trans-fats to improve CVD risk. Lipid Technology, 22(5), 103-106.

“The Experiment” Part 1

For those of you that don’t know me that well, I have spent the last 7+ years in post-secondary education trying to learn new and interesting things about the human body and in the process getting a few letters after my name. I’m a published scientific author and am currently completing my MSc. in exercise physiology, although my research is primarily focused on the physiology of obesity and weight loss (which encompasses all those buzz words like ‘metabolism’, ‘hormones’ and ‘appetite regulation’). I’m also a competitive athlete in my spare time and have drawn upon my knowledge and experience to help improve my own performance. The whole point of this blog is to bring some of the latest research and science on weight loss into the mainstream. I figured that it’s better to try and make a positive difference rather than sitting on my cynical ass and complaining about all of the garbage that’s being put out with the sole intent of putting large holes in the wallets of people just trying to make a difference in their lives on their quest to battle their own biology. I believe that it’s the unwritten duty of my colleagues and I to be able to translate and disseminate our research to the general public.

Yep, science still rules.

Since I love science, specifically the physiology of weight loss, I figured that it was appropriate to begin this epic journey through blogging by performing an exercise related experiment on myself. For those of you that have had the displeasure of knowing me for an extended period of time, you know that I myself have gone through some drastic physical changes. Before I get into the summary of my magical journey through body composition fluctuations, I want to briefly go over some important concepts in weight loss science.

1)  When someone gains fat, they will typically see both an increase in size of the fat cells as well as the number of fat cells. If you want to play the part of the pretentious intellectual jerk, slap on a pair of leather elbow patches and tell your overweight friends that their chronic positive energy balance has led to both the hypertrophy and hyperplasia of adipocytes. That’s a fancy way of saying that too many wings, nachos and beer has mysteriously led to the disappearance of one’s feet. Why is this concept important? The short answer is that even after weight loss, these fat cells may remain in the body, sitting there like hungry birds in the nest waiting for their mother to come back and feed them. Short of  good old liposuction, there’s really no easy way of getting rid of them. Luckily, we're not completely doomed as there are some biological mechanisms that may reduce the number during caloric restriction/negative energy balance (eat less and move more) (3)but the general advice is to not gain weight in the first place. This information may have been a lot more useful to me years ago, although perhaps like many other pieces of knowledge we accrue in our lifetime, it may have just as easily been ignored. 

The mysterious 'missing foot syndrome'.

2) Previous research (1, 2) as well as work from our own laboratory has indicated that the amount of energy our body burns may be depressed after gaining weight and then losing it again. As an example, if you took two identical twins (an ideal scenario in clinical research) forced one to gain weight and then lose it all (the experimental condition) while the other twin remained weight stable (the control), then the one that gained and lost weight would theoretically burn less energy in a day, assuming they performed the exact same tasks. This may be one of the reasons why so many people go through the ‘yo-yo diet’ phenomena and gain back weight after putting so much time and effort into losing it. I’ll go through it in more detail on another blog, but it seems that losing weight is a battle against our own biology.

So that being said, you’ll see that these two factors may play a role in my own personal physical history.

 In brief (sort of), here’s a third-person summary with some visual aids to keep you interested.

A young skinny immigrant boy arrives in Canada and begins to face the wrath of both his culture and the accompanying parenting which measure affluence through food intake. Years of a pallet riddled with guilt in conjunction with a decent medical system and some genetic assistance result in both large vertical and horizontal growth. The fondest memory in third grade was stepping on the scale and reading 99.5lbs, quickly running downstairs and gorging on some rice, running back upstairs and feeling a sense of accomplishment after reading three digits for the first time. This was also his first crude lesson in how thermodynamics applies to obesity research.

Social stigma and a fear of getting bullied in high school force the pre-teen to start running laps around his neighbourhood. He loses a substantial amount of weight by eating what amounts to a few apples a day and excessive exercise. He realizes that the appearance of his spine through a shirt whenever bends over and a really sad mother isn’t worth the hassle of looking like a Hollywood boy toy (6’2”, 130lbs).

 His rapid interest in football and some highly positive influences in the form of high school teachers resulted in him combining his love of food and lifting heavy weights. New surging pubescent levels of testosterone assisted in substantial muscle growth in addition to some newly accrued fat deposits. (~200lbs).

A football culture which encourages that ‘bigger is better’ results in large but gradual gains in fat and muscle. At 240lbs, he’s now a good size for a lineman in high school. The new possibility of playing college football results in a very brief but exaggerated weight gain, 6 month and 35lbs later. The composition of this weight was sadly not all muscle.

"Training for football" at the buffet with my brother and father as coaches.

       After a few years of college football and some other strength related sports on the side that involve wearing a plaid skirt, he’s reached a peak weight of 320lbs! Again, positive influences inform him that being able to block a large opponent may not necessarily be more important than preventing diabetes and cardiovascular disease. Additionally, he witnessed the paradox of a bunch of men his size referring to themselves as athletes and being unable to walk up a flight of stairs without groaning, making loud whistling noises through their nose or taking a breath after 5 steps and having to ice their knees afterwards.

For times when you can't afford to take chances, you can count on Immodium.

"Does anyone feel that draft?"

      ~200 concussions later and a month of constant vertigo, he decides that a future in football may not be in the cards for him. He joins two of his very close friends (who happen to be the ‘voices of reason’) in competing in weightlifting and actually focusing on school. In 8 months time, lifting heavy things for almost 20 hours a week and eating a little better results in a new weight of 255lbs and the provincial weightlifting title in a thin (ha!) pool of superheavyweights.

Concussions can lead to severe symptoms, like frequent and uncontrollable impractical nose picking.

Due to external factors and the lack of a training facility, he is forced to stop weightlifting. Without any sport in mind, he just ends up biking a lot to and from work (50km/week), working out and eating a low amount of calories relative to his weight. He weighs in at 215lbs at his lowest weight. In 1.5 years, he’s lost over 100lbs. He walks around campus and gets frustrated when his own friends the year before don’t recognize him or say hello. They claim it was because he had lost weight, be he secretly thinks that they’re just assholes looking for a way out of the friendship.

Not only did I lose weight, but I lost clothes as well.  I had to battle the evil Skeletor during my quest to find my pants. 

       He continues lifting weights, briefly competes in shot put and concentrates on hammer throw since he’s realized that individual sports are a lot more appealing to him than team sports. Maintaining a steady bodyweight of 220-225lbs, he decides that he wants to try and get much stronger and throw farther for his sport (even though his coach keeps insisting that strength is one of his only strengths in the sport and he needs to work on that whole ‘technical thing’... pffft). He hits a peak weight of 260lbs and is strong. The hammer travels farther.

Warning: Getting strong and beefy may result in doing  silly things like letting your significant other straighten your hair before work.

Graduate studies began to seep into his life along with his financial obligations. Training hits the backburner. The good news: He’s still 260ish lbs and strong. The bad news: The weight has been displaced on his body and the hammer isn’t going very far anymore

So, that being said, with my MSc. on the finishing block and my future PhD not yet commenced because, well, it’s not the future yet, I figured that it was an opportune time to try something a little different from all of the previous trials and tribulations. I have a lot of tools at my disposal including my knowledge/experience as a researcher/athlete/personal trainer as well as the new gym I work at called PhysXtreme which specializes in athletic training and has all the modern bells and whistles to make you a better athlete and manage your anger accordingly (sledge hammers, tires, chains, ropes, kettelbells and techno music... we’re still working on the last one).

Puking: Not a good weight loss strategy, but hilarious when your friends do it.

Stay tuned for PART 2 of this blog where I start outlining my nutty plan (nutrition, training) and hit you with a little bit of science here or there as well as some really bad jokes.









REFERENCES
 (Yup, you just learned something!)

1.            Astrup A, Gotzsche PC, van de Werken K, Ranneries C, Toubro S, Raben A, and Buemann B. Meta-analysis of resting metabolic rate in formerly obese subjects. Am J Clin Nutr 69: 1117-1122, 1999.

2.            Rosenbaum M, Hirsch J, Gallagher DA, and Leibel RL. Long-term persistence of adaptive thermogenesis in subjects who have maintained a reduced body weight. Am J Clin Nutr 88: 906-912, 2008.

3.            Sjostrom L and William-Olsson T. Prospective studies on adipose tissue development in man. Int J Obes 5: 597-604, 1981.