‘I tend to only spew facts’: Phil Mickelson gets in Twitter science feud to help famed golf instructor

Phil Mickelson flashes a thumbs up to a photographer while walking course at 2021 Ryder Cup

Phil Mickelson knows what he's talking about, and he has the scientific studies to prove it.

Patrick Smith/Getty Images

If you’re a high-profile member of the golf world, any tweet you make could be pounced upon by the reigning golf Twitter champion: Phil Mickelson. And if you reply to one of Phil’s tweets with some salt, be prepared for a response from Lefty himself, no matter who you are.

Mickelson is not the most prolific Twitter user on Tour, but he doesn’t shy away from mixing it up in the replies. If he’s not playing golf, there’s a good chance he’s cruising the timeline, looking for his next opportunity to jump into the conversation and drop some knowledge.

Phil Mickelson at 2021 PGA Championship
‘Sipping wine, half lit, tweeting’: Phil Mickelson celebrates PGA win with late-night tweetstorm
By: Kevin Cunningham

On Tuesday, legendary golf instructor Peter Kostis unexpectedly caught Phil’s attention with a tweet about swing training. It was a bit of a role reversal for Kostis, in that he was requesting help with a golf mechanics question, instead of dishing out the tips himself.

Kostis was mystified by non-dominant swing training, where golfers practice swinging from their weak side to improve their normal swing, writing, “someone has to explain the science behind non-dominant swinging improving dominant swing speed. Making my car go 0-60 in 4 sec. in reverse, doesn’t make [it] go faster in drive.”

Dr. Mickelson was more than happy to assist.

Two hours after Kostis posted his original tweet, Mickelson responded, and not with his customary jokes or sarcasm, but with pure science, writing, “Your body won’t accelerate faster than it can stop. Accelerating the opposite way strengthens the decelerating muscles in your normal swing. This will raise your body’s internal governor allowing you to swing faster.”

Unsatisfied with his own explanation, Phil expanded on the idea with another reply, “A race car’s top speed has a lot to do with its breaking system (not it’s ability to go fast in reverse) The human body’s ability to create speed is dependent on it’s ability to slow down and stop as well. Another way to think of it.”

That’s when a third-party tweeter entered the fray, challenging Phil’s theory and questioning his scientific credentials. As any good scientist would do, Phil clapped back with a footnote, referencing the studies where he got his information, and closing with, “I tend to only spew facts.”

That’s when well-respected golf biomechanist Dr. Sasho Mackenzie offered up his own explanation.

Whether or not there’s a golf lesson to be learned here is unclear, though Mickelson, who is a natural righty but plays golf lefty, is clearly a supporter of non-dominant swing training.

The Twitter takeaway is clearer: when faced with a roving Mickelson in your replies, tread carefully.

Kevin Cunningham

Golf.com Editor

As managing producer for GOLF.com, Cunningham edits, writes and publishes stories on GOLF.com, and manages the brand’s e-newsletters, which reach more than 1.4 million subscribers each month. A former two-time intern, he also helps keep GOLF.com humming outside the news-breaking stories and service content provided by our reporters and writers, and works with the tech team in the development of new products and innovative ways to deliver an engaging site to our audience.