Determining Functional Swimming Threshold

Don Macdonald training in 58 f fresh water for the English Channel
with support team under watchful eye of Doug McConnell.

There are a number of training assessment methodoligies. Understanding, especially as we age, how to train effectively, efficiently, and safely is critical to a long life and positive outcome.

TrainingPeaks WKO+ automatically generates training stress scores (TSS) for bike rides uploaded from a power meter and for run workouts uploaded from a speed and distance device. Triathletes who use WKO+ and appreciate this feature often wish that the program could do the same for swim workouts. Unfortunately, the swimming equivalent of a bike power meter or run speed and distance device does not yet exist. However, you can calculate TSS for your swims manually using a method we’ll describe in this article.

Why not simply use the same calculation for swim TSS that is used for running, in which the metric of pace is also used to quantify the training load? Because water presents more resistance than air, so the physiological stress of swimming increases with increasing swim speed faster than the physiological stress of running increases with increasing running speed.

The simplest, if not the most accurate, way to account for this difference in calculating TSS scores is to weight the “intensity factor” of swim workouts differently than it is weighted for run workouts. Specifically, we suggest, it should be cubed as opposed to squared.

Determining Functional Swimming Threshold Speed

Training stress score calculations in running and cycling are scaled according to the individual athlete’s current functional threshold pace (running) and functional threshold power (cycling), which correspond roughly to the lactate threshold running pace or cycling power. The lactate threshold can only be determined through laboratory testing, while the functional threshold is determined through field tests that are known to yield roughly equivalent results.

Similarly, the functional swimming threshold pace is a stand-in for the laboratory-determined swimming lactate threshold pace. There are two approaches that are most appropriate for the determination of swimming FTP. The first is the straightforward timed effort, where you swim as far as possible in a given time (e.g. 30 or 60 minutes). So, if you swim for 30 minutes and cover 1000 meters, then you can use the value of 33.3 m/min. as your FTP. Since the actual FTP is closer to the one-hour effort, it might be more advisable to perform a 60-minute test, or to take the value obtained for 30 minutes, multiply by two and subtract 2.5 percent (as most trained swimmers swim roughly 2.5 percent slower in a 60-minute maximal effort than in a 30-minute maximal effort). So again, if you cover 1000 m in 30 minutes, your 60-minute FTP would be 1900 m/hr or 31.7 m/min. This may seem like a minor difference, but due to the resistive aspect of swimming, small differences can have a substantial impact.

If you are not inclined to perform such long, exhaustive efforts in the pool, you may alternatively perform a critical velocity (CV) test. This method consists of two test efforts at different distances (200 m and 400 m) separated by a complete rest. Because complete rest is required for the results of a CV test to be valid, it is best to perform the first all-out effort at the beginning of one workout (after warming up, of course) and the next at the beginning of another. Record the time required to complete each effort and simply plot the results on a graph as distance vs. time. The slope of that line is your critical speed. Alternatively, a simple equation yields the same result:

Critical speed = (Distance of longer test swim – distance of shorter test swim) divided by (Time of longer test swim – time of shorter test swim)

For example, suppose you swim your 200m test swim in 2:02 (2.04 minutes) and your 400m test swim in 4:21 (4.35 minutes). Your critical velocity, then, is (400m – 200m) ÷ (4.35 min. – 2.02 min.) = 86.6 meters/min.

The results of your critical speed determination should yield a result that is very close to a 60-minute test or a laboratory-determined lactate threshold pace. Either of these results can then be used as the FTP for determination of TSS and performance modeling.

Calculating swim TSS

Now that you know your swim FTP, you can easily calculate the TSS for any swim workout using the following procedure:

1. Measure total distance covered for the workout

2. Determine time to cover total distance (not including rest periods)

3. Express distance vs. time in m/min to obtain normalized swim speed (NSS), which is analogous to the normalized power and normalized graded pace in cycling and running, respectively

4. Divide NSS by FT to obtain IF

5. Swim TSS = (Intensity Factor cubed) x hours x 100

For example:

Once you have determined the swim TSS, you can manually input values in Training Peaks WKO+ and then use the program’s analysis features for swimming as you do with running and cycling. Let’s look at an example of a specific workout. First, let’s suppose that your swim FTP is 75 m/minute. Next, let’s suppose you complete the following workout (remember, rest periods are not counted):

Warm-up: 200 m @ 3:20, 30 sec. rest (3:20 total)

Drills: 4 x 50 m @ 1:00, 10-sec. rest (4:00 total)

Main set: 10 x 100 m @ 1:15, 20-sec. rest (12:30)

Cool-down: 200 m @ 3:20 (3:20 total)

Total workout distance: 1,600 m

Total workout time: 23:10 (or 0.386 hours)

The average pace for the complete workout is 1,600 meters divided by 23:10 (23.16 minutes or 0.386 hours) or 69 m/min. The intensity factor for the complete workout is the average pace (69 m/min.) divided by the athlete’s functional threshold pace (75 m/min.) or 0.92. To cube IF, multiply it by itself three times (So, in this example, 0.92 x 0.92 x 0.92). So the TSS for the workout is So the TSS for the workout is 0.778x 0.386 hours x 100 = 30.1.

There are some important limitations of our do-it-yourself method of swim TSS calculation to bear in mind. First of all, although this simplistic approach can be effective, it should be noted that by simply tracking distance and time swum, the effects of rest periods on the sustainable efforts are neglected, whereas in cycling and running they are not, because power meters and speed and distance devices capture coasting and non-movement as part of the workout.

Similarly, our rough-and-ready method of calculating swim TSS lacks the exponential weighting of higher intensities that is done automatically with pace and power in the digital calculation of normalized cycling power and normalized graded pace, and which is an important means of capturing the exponentially greater stress imposed by higher intensities. That being said, the cubed weighting of the IF counterbalances this limitation to a certain extent.

These calculations ignore the differences between different swim strokes and the rather substantial differences in efficiency that result from good or poor technique. Finally, the impact of flip turns and push-offs is essentially neglected using this approach.

Still, it’s a lot better than nothing, which is what triathletes interested in logging their swim workouts on WKO+ have had up to this point!

This article was reprinted from and co-written by Matt Fitzgerald and Stephen McGregor, PhD. 

USMS National Open Water Championships 15K

USMS National Open Water 15k (9.3 mile) Championships from the perspective of kayaks, support crew and chief enthusiast me and several hundred other national caliber swimmers, coaches and avid supporters.

The beginning of any open water competitive swim can be frustrating for the calm and experienced, nervous for the un prepared, and nerve racking for the newbie no matter how capable. This is my 5th or 6th one of these both as a swimmer perspective and kayaker and I can say in the end its a team effort, including those that host the event. 

Our hosts from GRIN and NASTI masters teams in Indianapolis really do a nice job, giving up their potential to swim to help others become champions. This is one of the hallmarks of our sport, giving back.

This year was no different, than those of the past, stormy and grey weather threatened but held off. a few years ago when we did the 25k, swimming this many miles in hot water makes for a long day. 

The calm waters of Morse gave way to after winds chopping up the South End as usual, so much so I ran over Doug twice trying to stay close as a guide through the maze of buoys that makes up the turn/finish area for another lap. 

As you can see in this picture the shoreline undulates back and forth requiring the swimmer to be very precise in sighting. 

Here is Doug Mcconnell and myself heading up the East River last summer while circumnavigating Manhattan Island for a good idea of how close we operate.

A really strong fast swimmer can easily fall behind lifting their head too often, burning energy from dragging their hips low in the water. Experienced swimmers realize quickly that having an experienced kayaker is really critical, using them as a sight line on one side and the tree for example on the other. It's a choreographed dance on water.

In the end we had great fun, saw many old friends, made new ones and created hope for the future of our sport and the next race or chance to swim across a big body of open water.

Making It A Game - How to Get Across

Make It A Game

Outtakes from Article by Erin Barker on Navy Seal Training

Don about 14 miles into the Tampa Bay Marathon Swim

In this second part of the series we are breaking apart Erin Baker's article on why Navy Seals are so tough (Resilient) and what the everyday open water marathon swimmer can learn. 

When we do things repetitively we do take notice. More often than not however its an annoying type of recognition rather than motivating. I choose to make it a game.

• What’s one of the things people who live through disaster scenarios have in common? They make survival a game.

• Happiness expert Shawn Achor said the best way to deal with stress is to see problems as challenges, not threats.

• Kids do better in school when it’s treated like a game.

James, a Navy Seal, said the same thing about getting through the tough times at BUD/S:

Many people don’t recognize that what they’re doing at BUD/S is assessing your ability to handle a difficult circumstance and keep going.

It’s a game. If you want to be or attempt a seriously long swim in excess of say 6 miles and/or in cold water , you’ve got to play that game. You’ve got to have fun with it and you’ve got to keep your eye on the bigger picture.

A Navy SEAL Explains 8 Secrets to Grit and Resilience

Getting Across

Outtakes from Article by Erin Barker

In this series we are breaking apart Erin Baker's article on why Navy Seals are so tough (Resilient) and what the everyday open water marathon swimmer can learn. 

Purpose And Meaning

To say SEAL training is hard is a massive understatement. 

The initial vetting phase (“BUD/S”) is specifically designed to weed people out who aren’t serious.

How do you get serious? Grit often comes from a place of deep purpose and personal meaning. Here’s James:

"At BUD/S you have to know what you’re getting yourself into and what you’re there to do.I still mentor a lot of guys who are interested in trying out for BUD/S and they always ask, “What do I need to do to make my push ups better?” or “Can you teach me the proper swim technique?” My first question is always, “Why do you want to be a SEAL? What is it about being a SEAL that appeals to you?”

The research backs James up. Without a good reason to keep pushing, we’ll quit. Studies of “central governor theory” show our brains always give in long before our body does.

“…Overall, it seems that exercise performance is ultimately limited by perception of effort rather than cardiorespiratory and musculoenergetic factors.”

But this isn’t just true for athletics, it also holds for careers. In a study of West Point alums, those that had intrinsic goals (“I want to serve my country. I want to test my abilities.”) outperformed those that had extrinsic goals (“I want to rise in the ranks and become an officer because that’s a really powerful position and it’s prestigious.”)

So purpose matters. But what’s the attitude that keeps you going in the moment? It’s actually a bit less serious.

If your just trying it to see if you will get across, you will more than likely fail.

Barrington Ultra Marathon Swimmer helps others achieve their Dreams

Master Swimmer Don Macdonald knows in his heart that he would be gearing up to swim the English Channel if not for a cardiac arrhythmia that very nearly killed him.

Learning how to "take it easy" after the near-fatal episode, the 52-year Barrington man kayaked 28.5 miles around Manhattan Island on Saturday. Macdonald and his marathon swimming buddy and fellow Barrington resident, Doug McConnell, 56, have completed several similar grueling swims. But for the Manhattan Island Marathon Swim, Macdonald merely offered support from the kayak as McConnell swam the course to raise money in the fight against ALS.



"Kayaking," Macdonald says dismissively, "is very easy."

With the tide helping propel his kayak, Macdonald says his effort was more emotional than physical.

"There's value in helping other people achieve their dreams," Macdonald says, recalling how he rooted as his investment banker friend swam the English Channel in 2011 just before a storm wiped out Macdonald's scheduled shot at fame. "You want to revel in his success, and at the same time I say, 'Oh, man, I wish that could be me. I know I could do it.'"

A doctor on the medical team that saved Macdonald's life says the environmental engineer appeared to be in shape for that 2011 trek across the choppy, cold water that separates England from France.

"Fortunately, he didn't get to do the English Channel," says Dr. George Christy, a cardiologist with Advocate Good Shepherd Hospital in Barrington. "Swimming that distance in the cold of water for that long of time, there is a likelihood something adverse would have happened."

The bad weather that scuttled Macdonald's Channel swim gave the swimmer time to discover that a lingering pain in his shoulder blades was not just a training ache but a symptom of coronary disease.

"Here I am, a guy who swims 25 miles in 60-degree open water, and you're telling me I have clogged arteries?" Macdonald asked in disbelief.

Doctors inserted stents to open his narrowed arteries and put Macdonald on medication to regulate his heart.

"I'm fixed. They put the stents in. Let's go. Woo-hoo!" he remembers thinking. After a year of treatment and several stress tests on his heart, Macdonald was cleared to train again for a Channel swim this September.

"Even fit people develop coronary disease," says Christy, who adds that Macdonald developed another problem. "It's a false invulnerability people get, especially when they are endurance athletes. There's an aura of invincibility to some of these guys, and you can't blame them."

Having set swimming records during his high school career in Goshen, Indiana, competed on the swim team at Ball State University, played on the water polo team at Indiana University and enjoyed success as a master swimmer beating younger athletes, a confident Macdonald backed off his medications. "I made the decision to go with the less potent (medication), and it almost cost me my life," he says.

"He goes out for a jog when it's 100 degrees, which I wouldn't recommend for anybody," Christy says. Macdonald ran up to his home in the midst of a block party and "crashed," the doctor says, explaining how the athlete's heart went into ventricular fibrillation, an uncoordinated heart rhythm, which can be fatal.

A retired nurse on the scene performed CPR and a medical emergency team got him to Advocate Good Shepherd Hospital's emergency room within minutes. Knowing Macdonald's tolerance for long swims in cold water, doctors used a device to put him in a hypothermic state that lowered his body temperature.

"Neurological recovery was key," says Christy, noting that hypothermia slows the metabolic process that can cause cognitive damage when the brain goes without oxygen. Tests showed his heart and blood pressure were good. But Macdonald's life was in danger for days.

"Is he or is he not going to wake up? It was all guesswork until we warmed him up," Christy says.

"I wake up three or four days later," Macdonald says. "I don't remember a thing. I don't remember seeing a light at the end of the tunnel. Nothing."

Knowing how close he came to dying and leaving behind his daughter, Rachel, 16, and his wife, Jennifer, Macdonald says he wants others to know the value of stress tests and good cardiac care.

"The harsh reality is very scary," say Macdonald, who practices kayaking in Lake Zurich and on Lake Michigan, but misses swimming. "I have been in the swimming pool three times, and just sort of paddled around. I'd be lying to you if I didn't say it was scary."

Long, open-water swims have been part of his life since high school, when he and pal Steve Conder swam 8 miles across Lake Wawasee in Indiana. Macdonald has completed swims from Alcatraz off the coast of San Francisco and lighthouses off the coast of Boston. He and McConnell swam marathon races in Crystal Lake, Minnesota and Wisconsin.

"We were beating kids in their 20s and 30s pretty regularly," Macdonald says. "One night at the dinner table, drinking some wine, we said, 'How about the English Channel?'"

McConnell became the 48th person older than 50 to swim the Channel and continues to do well in marathon swims. Macdonald, who has a device implanted in his chest to shock him if his heart gets out of rhythm, stays in the kayak.

"If it goes off when you're facedown in the water, you could drown. After all this, to die drowning, that would be really embarrassing," Macdonald says. "But I just can't sit on a floaty and hang around. It's not me."

When talk turns to his English Channel quest, he repeats the mantra, "Sometimes you have to let that go." Then he pauses.

"I'll tell you," Macdonald says, softening his voice as if he's sharing a secret. "I'm not so sure about that."

Reprinted with modifications from Daily Herald, Burt Constable.

Fatal Arrhythmias in Open Water Swimming

Fatal Arrhythmia's in Open Water Swimming: What's the Mechanism?

Reprinted from Lawrence L. Creswell, M.D.

Introduction by Don Macdonald: I recently had a sudden cardiac event, collapsed, received life saving help immediately and found to have arrhythmia problems perhaps brought on by exercise, Well I survived and now find myself with an implanted ICD to prevent such future events. I was running, which I jokingly say was the problem, instead of swimming. I think ICD stands for "I Can't Die".

However my experience now takes me down a path relatively untraveled since only about 1% of such incidents leave survivor's. So onto the next chapter of my swimming journey just One Stroke At A Time.

Cardiac rehab has me exercising already and I am hopeful to return to the pool in the near future.

We've talked previously here at the blog about the general issue of sports-related sudden cardiac death (SCD).  And we've also talked about the specific issue of swimming fatalities during triathlons and open water swims.

But what triggers a sudden, fatal arrhythmia during open water swimming?

The answer isn't known and perhaps it will never be known with certainty.  But a recent report from a group of scientists in the U.K., though, suggests a very plausible mechanism.  Their idea is worth considering.


What's been learned from studies on runners?

As I've mentioned previously here at the blog, sports-related SCD has been best studied in the setting of long-distance running events.  Last year, Dr. Kim and colleagues in Boston reported on a decade-long study of runners with race-related SCD [1].  These investigators found that fatalities during marathons are not distributed uniformly along the race distance.  Instead, they predominate during the final 3 miles or so.  And interestingly, fatalities during half marathon events also predominate during the closing miles.  But why?

In the running population, we know from autopsy studies that the majority of victims have some sort of (often previously unknown) heart disease.  And something happens during the closing miles of the race.  In the words of the investigators, their "findings suggest that demand ischemia (i.e., ischemia due to an imbalance between oxygen supply and demand) may be operative in exercise-related acute coronary events during long-distance running races."  The leading hypothesis is that this mismatch in blood (or oxygen) supply and demand in the heart occurs when the runner picks up the pace, producing an adrenaline surge and increased physiologic demands on the heart, once the finish line is mentally within sight.

Based on this hypothesis, the International Marathon Medical Directors Association issued an advisory in March, 2010 that recommended, among other things, that athletes "not sprint the last part of the race unless you have practiced this in your training."

The concept here is that a susceptible heart (in a susceptible athlete) is triggered at a particular moment in the race to have a fatal arrhythmia because of a specific trigger.  The surge hypothesis might not explain all running race-related deaths, but is a plausible explanation for the physiology behind the majority of the deaths that occur late in a race.

It's very likely that the same concept is in play in triathlon-related sudden cardiac death.


What's going on in triathlon?

In triathlon, athletes have died at any point during the race--from the first few strokes of the swim through the final strides of the run.  And a couple athletes have collapsed with SCD even a few hours after the finish.  But the majority of deaths have occurred during the swim.  USA Triathlon issued a report last year that summarizes these facts.

What might be the trigger for sudden cardiac arrest during the swim portion of a triathlon?

Recently, two researchers in the U.K.--Michael Shattock and Michael Tipton--have offered a new hypothesis that they have labeled autonomic conflict [2,3]

To understand their hypothesis, we first need to talk for a moment about some features of the heart's physiology.


Sympathetic and Parasympathetic Influences

One component of our nervous system is called the autonomic system.  This portion of the nervous system is involuntary, responding to internal and external stimuli below the level of our consciousness.  The autonomic nervous system has 2 different divisions--the sympathetic and parasympathetic systems.  Each of these divisions can operate independently, often with opposite effects on the body's organs, including the heart.

We often think of the sympathetic nervous system as being excitatory--providing the so-called "fight or flight" response.  When activated, the sympathetic nervous system has several effects on the heart:  an increase in heart rate, vasodilation of the coronary arteries (leading to more blood flow), and increased contractility (contraction strength) of the heart muscle.  And importantly for athletes, activation of the sympathetic nervous system also increases the blood flow to the skeletal muscles, decreases blood flow to the abdominal organs, and opens up the airways of the lungs.

In contrast, the parasympathetic nervous system has an inhibitory effect on the heart, acting to restore a baseline heart rate after sympathetic activation and by slowing electrical conduction in the specialized areas of the heart's electrical system known as the sino-atrial (SA) node and the atrio-ventricular (AV) node.  In well-trained endurance athletes, the parasympathetic nervous system is often highly developed, and is one cause of a very low resting heart rate.


A Hypothesis

Drs. Shattock and Tipton have proposed a mechanism where sudden activation or sudden increase in activation of both the sympathetic and parasympathetic nervous systems can produce a fatal arrhythmia.  This idea is supported by studies in isolated hearts as well as in healthy volunteers.

Let's say that an athlete's heart might be predisposed to an arrhythmia because of one or more anatomic or physiologic conditions such as:  congenital or inherited long QT syndrome, coronary artery disease, myocardial hypertrophy, ischemic heart disease, or pathologic hypertrophy (eg, hypertrophic cardiomyopathy).

During an open water swim, an athlete's sympathetic nervous system is activated because of physical exertion, (relatively) cold water temperature, anxiety, or even anxiety or overcompetitiveness.  The parasympathetic nervous system is activated because of facial wetting, water entering the mouth, nose, and pharynx, and extended breath holding--and particularly so, just at the moment of breaking a breath hold.  At that very moment, there can be maximal parasympathetic activation.

These scientists suggest that this autonomic conflict--between the sympathetic and parasympathetic nervous systems--is what triggers a sudden, potentially fatal arrhythmia.


It's Plausible

This is a plausible hypothesis.  It fits with the observations that have been made on victims of sudden cardiac death during open water swimming.  And it fits with the general concept of a susceptible heart and an arrhythmia trigger that seems to be in play in victims of SCD in other sports.



References

1.  Kim JH et al.  Cardiac arrest during long-distance running races.  N Engl J Med 2012;366:130-140.

2. Shattock MJ, Tipton MJ.  'Autonomic conflict':  a different way todiedu  ring cold water immersion?  J Physiol 2012;590:3219-3230.

3.  Tipton MJ.  Sudden cardiac death during openwater  swimming.  Br J Sports Med 2013. Online in advance.


Related Posts

1. Sports-relatd sudden cardiac death in the general population

2. Athletes, sudden death, and CPR

Endurance Athletes - Nutrition Matters and corn products are not healthy for you long term

Corn is not a vegetable

Reprinted from The natural nutritionist

Endurance Athletes, pay attention to what you are eating as 'false' energy from corn products can adversely affect your cardiovascular system, causing inflammation long term. As an endurance athlete we eat lots of food but processed foods such as GU gels, snack bars, Gatorade, smoothies, the list goes on and on...carry very poor nutritrients and for some of us with genetic family traits, this can be harmful long term.

Parents, with kids in school and athletics. Please engage with your school and coaches to learn exactly what your kids are being fed. 

Just like peanuts are legumes and not nuts, corn is a grain, not a vegetable. But (whole)grains are good for me aren’t they? No. 

The truth is that we’ve been fed that lie to support industry. (Just like how the food pyramid was created by the agricultural industry!) Corn in particular, is the perfect industrial crop. According to Toby A.A. Heaps, author of The Killer Kernel, it has an abundant source of cheap interchangeable calories, and with a large amount of fertilizer, can be grown rapidly and predictably often on a one-person, one-machine farm enterprise.

Before I continue, let me get one thing straight. I’m not talking about the occasional corn on the cob at your family barbecue, but rather the reliance on corn as an every day food. Cornflakes for breakfast. Corn cakes and Vegemite as your afternoon snack. Cornbread. Corn starch, a common gluten free substitution; often found in low-fat products. ANYTHING containing high fructose corn syrup (HFCS). It’s simply not real food. All you are doing is jumping on the blood sugar-insulin roller coaster, which leads to chronic hunger, energy peaks and troughs, and the all-too-common 3.30-it is. Significantly, chronically elevated insulin levels are the enemy to sustainable weight loss, lean muscle mass development and weight maintenance.

Why corn is not part of my daily food pyramid

1. Corn is a sugary, starchy, low-nutrient grain.
2. While gluten is by far the worst culprit, grains can still be inflammatory and are high in phytic acid, substances that can inhibit nutrient absorption. The problem with high levels of phytate is mostly relevant when gut health is sub-optimal, and the overall nutrition is deficient in micro nutrients and essential food sources. Something you will definitely need to consider if you have been following our traditional food pyramid.
3. The over consumption of grains decreases the release of our major digestive and satiety hormone cholecystokinin, or CCK.  This is known to be one of the major causes of insulin resistance, the precursor to obesity.
4. There is not a single nutrient, vitamin or mineral present in grains that you cannot obtain from natural, wholefoods.
5. Corn is used to fatten pigs, cows and other livestock, and is the key ingredient in HFCS, the leading cause of obesity in America. Enough said?

Is corn GMO?

Overseas, corn, otherwise known as maize, is genetically modified (GM) for greater resistance to pests and viruses, higher nutritional value and longer shelf life. In Australia, imported GM corn is predominately used as cattle feed and thankfully, has not been approved for farming. 

However, GM corn may have entered our market through imported foods like bread and cereals, corn chips, gravy mixes and sports drinks. Avoid these products like the plague.

On a positive note, before any of these products are sold in Australia, they are checked for safety by Food Standards Australia and New Zealand (FSANZ). According to Australia’s Chief Scientist, the law in Australia requires that food labels must show if food has been GM, or contains GM ingredients, or whether GM additives or processing aids remain in the final food product. Please avoid GM foods, but that’s another story all together.

The moral of the story?

There are far better choices than corn. Focus on nutrient dense, real food. And if you do buy food products with a label, read them carefully. 

References

Genetically Modified Foods. Food Standards Australia and New Zealand. Available: http://www.foodstandards.gov.au/consumerinformation/gmfoods/.

Genetically modified food explained. Australia’s Chief Scientist. Available: http://www.chiefscientist.gov.au/2011/11/genetically-modified-food-explained/.

Haros M, Bielecka M, Honke J, & Sanz Y. (2007). Myo-inositol hexakisphosphate degradation by Bifidobacterium infantis ATCC 15697. International Journal of Food Microbiology, 117(1), 76-84.

Heaps TAA. The Killer Kernal. Corporate Knights. Available: http://www.corporateknights.com/article/killer-kernel.