Fat burner or fashion statement? Depending on one’s personal preference, weighted vests can deliver either.

While some military and law enforcement types have used the items for training, a wider range of individuals are picking them up for more enhanced cardio workouts and improved endurance. Whether training in weighted vests improves bone density is still a matter of debate.

For starters, physical trainers advise bulking up by adding 5 to 10 percent of your body weight. While the more athletically inclined might increase that percentage over a period of time, one baseline is to avoid piling on more than 20 percent of your body weight. The versatility of walking and the popularity of rucking lend themselves to weighted vests. Last year 115.3 million Americans walked as a form of fitness compared to the 114 million who did so in 2023, according to Statista.

Equinox is upping its performance training with what it is calling the world’s first treadmill-based hiking class, “Fully Vested.” The wellness operation has introduced a proprietary weighted vest called “the Precision vest” that people can use for the 60-minute class or their own adventures. The item was developed in collaboration with Kilogear and costs $375 for a 20-pound version.

The class and the vest are the latest evolution of Equinox’s Precision Run ecosystem. Precision Run’s creator David Siik said skeptics will be surprised by “what a low-impact way it is to have a really big energy burn in such a short amount of time. It also helps you to discover how your body moves in a very different way,” he said.

Siik was inspired fashion-wise by Angelina Jolie’s role in “Lara Croft: Tomb Raider” and, as he says, the sturdy and tactile vest often makes wearers feel like “a bit of a badass.”