The central principles about swimming faster I advocate in this series are universal when it comes to terrestrial mammals trying to move through an aquatic medium at higher speeds that before. These are:

1) Our human instincts – encoded in our DNA by millions of years adapting to a terrestrial environment – will virtually always lead us to actions that limit, not increase, our speed potential.

2) The content of workouts that focus on faster strokes, and bigger lungs and muscles are highly inefficient when it comes to addressing the physical limitations that keep us from swimming faster.

3) Therefore any effort to swim faster must be strategic and sustainable — and should be imprinted by purposeful practice for countless hours before racing.

These principles are true for any distance. They’re true in the pool or open water. They’re true whether you’re racing or swimming for fitness or just testing your limits. But they are true in a particularly compelling way when swimming in a triathlon. This is because:

1) The problem of the almost-never-rational way we respond to an urge to swim faster is hugely compounded when you’re a relatively inexperienced swimmer surrounded by a congested pack of churning arms and legs with no safe place to catch your breath.

2) The open-water-distance swim in a triathlon requires you to swim thousands of uninterrupted strokes, rather than 20 or so between walls in a pool.

3) The goal of the race isn’t to swim fast, but to complete three disciplines as fast as you can. Your chance of saving much from your final time is very limited in swimming, while your chance of severely undermining your final time by “spending too many heartbeats” during the swim is significant.

Part 2 explains the special need for swimming strategically – and never heedlessly – in triathlon. The challenges of TriSwimming are not only greater than for cycling or running; in fact they’re greater than for any other form of swimming.

Five years ago, as he was turning 60, Amby Burfoot, came to me for instruction, to sustain and complement a distinguished running history of over 40 years. In 1968, as a senior at Wesleyan (where he was a teammate of both Bill Rogers and Jeff Galloway) Amby won the Boston Marathon. Later that year he missed the American record in the marathon by just a second in Fukuoka Japan. As an editor of Runner’s World since 1978, Amby has been one of the most respected voices in the running world.

Amby has since become an avid, even passionate, TI swimmer. Some time ago he shared with me a key insight he’d gained into the difference between running and swimming. He said, “Running faster isn’t very complicated. My body just knows how. Swimming faster is highly complicated.”  He also said “It takes a little more energy to run a little faster; it takes a lot more energy to swim a little faster.”

I’d known that from instinct and experience. Though I’ve swum hundreds of pool and open water races over the last 45 years compared to only a dozen or so road races, I still find it much easier to shift from effective to wasteful effort when trying to swim faster  — an error I had no problem avoiding when I ran.

So I was made curious whether it was possible to quantify the relative efficiency of swimming, cycling, and running in Converting Heartbeats into Locomotion. I took that question to another good friend, Michael Joyner, M.D. an exercise researcher at the Mayo Clinic, who also had direct experience in all three. Mike ran a 2:24 marathon in his 20s and swam a sub-21-minute 1500 meters in his 40s. In his 50s he’s begun triathlon training.

Mike estimated that an increase of 10 percent in effort would convert to speed increases of 10 percent in running, about 6 percent in cycling and at best 3 percent in swimming. For an unskilled swimmer that conversion would likely be much less.

So I applied Mike’s efficiency factors to the median splits from the 2008 Hawaii Ironman: An effort increase of 10% would improve the median splits  by 33 minutes on the run, 23 minutes on the bike, but less than 3 minutes in the swim.

For triathletes, the main takeaway is that all your thoughts and actions in swimming should be directed toward achieving a steady sustainable pace with the least effort. Heartbeats you ‘save’ in the water will bring a far greater payoff when ‘spent’ on land. As I’ve written previously a simple way to view the swim leg is that you need to swim to the start of the actual race, which begins only when you mount your bike.

Simply swimming easily during the race isn’t enough. To get the maximum benefit from this insight, your swimming practice should be relentlessly focused on imprinting ease as a habit while also maximizing efficiency.