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by Terry Heggy

January 21, 2020

You can diagnose stroke flaws that are hidden from deck-level observation

The birds-eye view you get from coaching on deck lets you scan the entire pool. You can see who’s working hard and who’s loafing, who’s lifting their head to breathe and who’s crossing over on hand entry. From your elevated position, you can observe and correct a multitude of stroke flaws, and your voice carries extra authority as you tower over your aquatic minions. A coach who constantly walks the deck and generously distributes helpful feedback will soon see swimmers succeed.

But there’s a lot going on in the pool that you simply can’t perceive from the sidelines. You’re a long way from the center lanes, there’s glare on the surface, and lane ropes disrupt your line of sight. For full access to the visual stroke data you need, you must see what’s underwater.


The best way to analyze underwater performance is with slow-motion video. You’ll spot opportunities for correction that you might miss at full speed, and you can watch the video repeatedly to determine what feedback you want to give. Optimal video shows the swimmer from multiple angles so you can spot and eliminate drag that is unseen by a deck observer. Slow-motion video also reveals flaws in hand and wrist position as well as synchronization issues that are hard to spot at full speed.

There are several ways to acquire underwater video, including:

  • Via an underwater window (if your pool has one)
  • From the deck with a submerged camera attached to a selfie stick (or taped to a broom handle)
  • From a handheld camera operated by someone in the water
  • Using an underwater robot

Underwater camera robots are still quite pricey, but affordable cameras are available for the other options. You can even get an inexpensive waterproof bag that lets you take underwater video with your phone.

I prefer to shoot the video myself to ensure I get the shots I want, using fins to propel myself beside the swimmer I’m recording, breathing through a snorkel so I can keep my eyes on the viewfinder. But if you have a reliable volunteer among your swimmers, it’s great to delegate the videography to someone who’s already wet.


When using your own eyes to watch swimmers underwater, watch the stroke from multiple angles.

  • Front—As the swimmer comes toward you, watch for alignment/crossover, hand depth, hand pitch, body rotation, head position, etc.
  • Side—As the athlete swims past you, watch for catch position and vertical forearm engagement, stroke length, hand pitch at the end of the stroke/release point, kick depth, breathing motion, etc.
  • Behind—Follow the swimmer to watch for fishtailing, ankle flexion, body rotation, kick timing/technique, etc.
  • Underneath—Lie on the bottom as the swimmer passes overhead and watch for bubbles, spinal alignment, shoulder wobble, etc.

Scuba-certified coaches have the advantage of longer-duration viewing. Scuba-type weight belts or stiff-arming a lane rope may help breath-holding coaches keep from floating to the surface before they’re finished watching. Whenever you’re in the water, take care to avoid collisions with other swimmers.

An alternative to submersion is to have swimmers stand in shallow water (or on deck) and show you how they pull while they’re vertical. They won’t exactly duplicate the movements they make when swimming, but they’ll often reveal mechanical or conceptual issues. Always get permission before touching or manipulating a swimmer’s limbs, but when appropriate, take advantage of the fact that some swimmers learn best when you physically move their arms/hands into the desired positions.

If possible, give feedback to the swimmer immediately. It’s easy to forget the details you’ve observed if you wait until the end of practice to share what you saw. Jotting your observations in a notebook or phone app helps you follow up later to ensure that the corrections stick.


The effort required to obtain underwater visuals provides amazing benefits for the swimmers while enhancing your abilities and reputation as a coach. But it does come at a cost.

  • When you focus on one swimmer, you risk neglecting the other people in the pool. Verify that there’s a certified lifeguard watching the rest of the pool, and ensure that the other swimmers can continue their workout without disruption.
  • Swimmers pay more attention to form when they know they’re being watched and may not exhibit the same technique they use when doing their “regular” stroke. Compare your clandestine surface observations with what you see underwater to ensure your feedback is optimally helpful.
  • The time and attention you commit to underwater analysis goes above and beyond your responsibilities as workout designer and manager. Consider offering underwater analysis as a separate service at additional cost at a time outside normal workout hours. You may want to offer a stroke clinic, engaging other local coaches, your LMSC, or the USMS National Office to help.


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