Swim paddles are advertised and promoted as swim-aids building power and strength. They're also alleged to lengthen the simmer's stroke at the front end: the paddle's large surface area causing a long glide, or feeling of glide, commonly quantified as Distance per Stroke (DPS).
Over the last 20 years, the reengineering and development of the modern-day paddle has resulted in an architecture with significantly larger surface areas and varying shapes, each design touting its own benefits. We've reached a stage now where paddles are either large, very large or super-sized. In assessing the benefits of such paddles, remember they're created and developed by national level swim coaches, to train their national level athletes.
In my view, most of these large paddles do not benefit triathletes or non-elite swimmers.
Almost all triathletes and non-elite swimmers lack the strength, power, and specific muscular endurance to drive large paddles through the water. Most will compensate by dropping their elbows quickly or otherwise resorting to an improper stroke. These incorrect repeated movements only serve to imprint poor mechanics. The swimmer may feel he or she is training harder but there is almost never any real gain technically.
They also slow stroke rate, the number of swim strokes per minute, which is already a limiter for many triathletes. Low stroke rates equal slow swimming; lower stroke rates, even slower swimming. A separate post will address stroke rate as it deserves its own discussion.
For these athletes and swimmers, these larger paddle types are harmful.
I recall one swim workout with a well-known pro triathlete, a front-of-pack swimmer, who was using a then newly introduced paddle, a behemoth in mass and shaped like a stealth bomber. His stroke breakdown was immediately obvious to me, his elbows collapsing to his ribcage. I tried to point out that these giant paddles were not working for him and, in fact, were actively undermining his training. In retrospect, I should have minded my own business: he would have no part of my advice and fervently believed that the manufacturer's claims worked for him. He knew he was swimming faster - which he was, with the paddles. Without them, he would be left with no extra benefits and a wrecked technique. Like most triathletes and non-elite swimmers, he would have been much better off - ultimately building more speed, strength and specific endurance - by abandoning these 'trash can lid' paddles and simply using pull buoys and an ankle strap.
Naturally, in an article this short, I'm generalizing. Some paddles do have their place in the training schedule. If you want to try paddles, find a design that works for your particular mechanics, and one that fits your hand. Generally, smaller is better.
Disclaimer: My notes are written for the general swim and triathlon audience. Some statements are quite broad while others are specific. Every athlete, every swimmer is different. Learn to recognize what applies particularly to you so that you can make the decisions that enable you to train and compete most effectively.
Gerry Rodrigues has been coaching triathletes since 1983, and presently coaches "Tower 26" www.tower26.com. He's a US Masters coach of the year; a world and national masters champion; coach and advisor to world champion open water swimmers, triathletes, and Olympians; former owner of SWIM Magazine and publisher of Swimming World and Swimming Technique Magazines. He says: "I do not have a monopoly on information, rather continue to learn from athletes and other coaches, loving every day of it."