I've long been skeptical about the direct-to-consumer approach in digital health and of those who push slick apps and gadgets to a market that wants simple rather than flashy. "The vast majority of healthcare spending comes not from workout freaks and the worried well, but from chronic diseases and acute care," I wrote in a particularly inflammatory column in February.

Now I'm starting to believe that some DTC products are finding markets in the limited but potentially highly lucrative niches of military personnel and elite athletes.

I came to this realization last Friday at the University of Southern California's seventh annual Body Computing Conference in Los Angeles.

Readers of MobiHealthNews probably already know about the BioHarness, a wearable sensor from Annapolis, Md.-based Zephyr Technology that athletic apparel manufacturer Under Armour has embedded in a shirt. It's been used at the National Football League Scouting Combine and to measure stress levels in firefighters, soldiers and NASA astronauts.

Clarke Lethin, managing director of the USC Institute for Creative Technologies, is an ex-Marine colonel who sees promise in biosensors for keeping service members physically and mentally healthy. "We have to have the tools" to prepare and predict before something tragic happens to those in combat, according to Lethin.

But military brass want to know who, what, why and how they are measuring, he said. That's where digital health experts come in. "We look to this community to help us understand some of these questions," Lethin said at the Body Computing Conference.

You might also know about wearable sensor maker MC10, Cambridge, Mass., which teamed up with Reebok to market Checklight, a helmet insert that measures blows to the head. One of the developers of that technology was Isaiah Kacyvenski, an eight-year veteran of the National Football League—and a Harvard MBA—who suffered seven diagnosed concussions during his playing career.

Kacyvenski, who has agreed to donate his brain for research into traumatic injuries when he dies, shared part of his chilling story during Q&A portion of a Body Computing Conference session.

The National Basketball Association won't let its players wear sensors during games, according to Paul Robbins, director of elite performance at Northbrook, Ill.-based sports statistics firm Stats LLC. But the company, with its SportVU system, tracks athlete movement and ball possession with overhead cameras in about half the NBA's arenas and at all UEFA Champions League soccer matches in Europe. (He said every NBA venue will have the technology for the upcoming 2013-14 season.)

SportVU measures player speed, distance traveled, separation from other players, time of ball possession and even the trajectory of shots, for the benefit of teams, athletic trainers and TV viewers.

USC women's basketball coach Cynthia Cooper sat in on that session and said she wasn't sure how much players would value all these data points, since they tend to care more about how they feel than they do about the technology. However, she said coaches, trainers and administrators would welcome the information as a means of assuring athlete fitness, preventing injuries and achieving her team's primary goal each year: "Beat UCLA."

Apparently, some things never change.