San Francisco 49ers tight end George Kittle opened up about a unique training and recovery method that he says has improved his performance and sleep — and comes with some unanticipated side effects, as reported by The New York Post.

During an appearance on the Bussin with the Boys podcast, Kittle, 31, discussed his use of the Vasper machine, a high-tech recovery bike that uses blood flow restriction, compression, liquid cooling, and interval training to simulate high-intensity exercise without the wear and tear of conventional workouts.

Image Credit: © Kirby Lee-Imagn Images

“I do it a little bit during OTAs, but as soon as I get back in the summer, it’s like my cardio every day at the end of my workout,” Kittle said. “I’ll go lift, run my routes, run hills, and then I’ll do a 20-minute Vasper session, four days a week. I love it.”

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Kittle claimed the machine helps him sleep deeply and even reported vivid dreams. However, it was another result that caught listeners’ attention.

Kittle described the alleged increase in testosterone levels associated with the training.

“The main selling point is you, um, blow huge loads. That’s how it was sold to players. It boosts your testosterone, you sleep really well, you’re going to feel great.”

The veteran tight end, who has been married since 2019 to Claire Kittle, said he was skeptical at first. “I was like, ‘Oh, that’s bullsh*t.’ Not bullsh*t,” he admitted.

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He added that the practice has become popular among some NFL staffers.

“In 2019, there were six or seven coaches that were doing it all the time… one of my [offensive coordinators], he was in there all the time, going to town.”

Following a rare early offseason due to the 49ers missing the playoffs for the first time since 2020, Kittle said he’s mentally and physically ahead of schedule.

“The one benefit of not making the playoffs is you get an entire month off. I haven’t had January off since 2020,” he said. “Mentally and physically, I’m light years ahead of where I was last year.”

This video is wild

George Kittle talks about using a Vasper System for his training:“It knocks you the fuck out at night. You sleep so well and you have wild dreams. The main selling point is that you blow huge loads… That’s how it was sold to players that it boosts your… pic.twitter.com/cU9iGjMocF— Coach Yac (@Coach_Yac) June 24, 2025

Kittle signed a four-year extension with the 49ers in April worth up to $76.4 million, including $40 million guaranteed, tying him to San Francisco through 2029.

He finished the 2024 season with 78 receptions for 1,106 yards and eight touchdowns, becoming the fifth tight end in NFL history to log at least four 1,000-yard seasons.

The 49ers are scheduled to open their 2025 season on Sept. 7 against the Seahawks in Seattle. Veterans report to training camp on July 22.

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