Newton Sir Isaac Guidance Trainers

Since its launch two years ago, Newton Running’s shoe philosophy has been seen as revolutionary and at times highly controversial. As Gear Junkie readers know, I am a fan of Newton’s odd outsole, which includes minimal heel-to-toe drop to discourage a rolling stride and lugs underfoot to keep a runner forward and fast.

For runners intimidated by the company’s original shoe offerings, which skew aggressive and unforgiving on form, Newton ( has unveiled a new model for this fall. The men’s Sir Isaac Guidance Trainers and women’s Lady Isaac Guidance Trainers have most of the same attributes as the original Newtons, including the midfoot sole lugs, called “actuator lugs.” But with a wider heel and forefoot, increased toe spring, a midsole support shank, and a beveled heel, the shoes are more forgiving to people not used to the “Newton stride.”

Newton Running Sir Isaac Guidance Trainers.jpg

Newton Running Sir Isaac Guidance Trainers

The company says the Sir Isaac and Lady Isaac will help a runner “make the transition to a more efficient midfoot/forefoot running technique” and “embrace their natural running form.” This form would be a midfoot strike with shorter steps and a faster stride cadence — a style that is sometimes referred to as a barefoot running technique.

Both Isaac models — due out in September — have a breathable closed mesh upper. The sole has been beefed up for durability, including a hard plastic protective covering on the midfoot. The rubber feels much more durable than other Newton models I’ve tested, which have soft rubber that shows wear after only a couple runs.

The actuator lugs on the Sir Isaac and Lady Isaac have been updated. They have a slight tread pattern for traction on wet surfaces, and they are made of a harder-wearing carbon rubber for added durability.

Newton Running Sir Isaac Lugs.jpg

Bottom view: Sir Isaac Guidance Trainers, ‘actuator lugs’ exposed

Like past models, the Isaacs remain at the upper echelon of the running shoe pricing structure. They will cost $149.

The company quotes the Sir Isaac as weighing 10.9 ounces (men’s size 9) and the Lady Isaac at 8.9 ounces (women’s size 7). On my scale, they were 13.4 ounces per shoe (in a size men’s 12.5), which is lightweight for this kind of running shoe, though about an ounce heavier than the Newton Neutral Racer model I employ for training and events as long as marathons.

Newton Running Lady Isaac Guidance Trainers.jpg

Newton Running Lady Isaac Guidance Trainers

I took two five-mile test runs in the Sir Isaacs this week. My initial reaction was good. They are comfortable and indeed more forgiving than other Newtons I have tried. There is less negative feedback underfoot if you strike with the heel, letting a runner ease into a midfoot-strike technique while learning to run the Newton Way.

—Stephen Regenold writes about outdoors gear at

Posted by Gina - 08/19/2009 02:43 PM

What kind of pronation do they support?

Posted by brett - 08/19/2009 03:20 PM

I’m a HUGE Newton fan & barefoot training advocate and I frankly cannot wait for these shoes! The “Guidance Trainers” will span the gap between my barefoot/Vibram KSO workouts and my Newton Gravity Racers – AND allow for trail running!

Posted by Stephen Regenold - 08/20/2009 09:53 AM

The company says: “The Isaac features a dual-density universal posting system in the midsole to help stabilize neutral runners, pronators and supinators.”

To me, in my short test so far, they feel like a neutral shoe. (But that is what my foot is, too.)

Posted by Christine - 08/20/2009 10:54 AM

I love my Newton Gravity Trainers right now and I’m a major supinator and run short distances (5k)…do you suggest I use these Sir Isaac Trainers if I wanted to run longer (10k)?

Posted by Joey - 08/21/2009 09:28 AM

I’ve used the Newton racers for a full season now and I love them. They have helped my cadence and overall running style. I’ved used them in all my races that involve running includes 10 k’s, halfs, and IM. They are fantastic.

Posted by Stephen Regenold - 08/24/2009 10:46 AM

Christine — According to Newton, the performance is very close for Sir Isaac and the Gravity Trainer, however Isaac will have better wear and slightly more lateral support. This would be a good fit for your 10K runs.

Posted by Alex - 08/31/2009 04:14 PM

I just got a pair to wear test. Definitely a smoother transition from a normal trainer to the Sir Isaac as compared to the older Newton models.

Posted by Rob - 10/12/2009 03:18 AM

I’ve just received my first pair of Isaac Newton trainers and very impressed. Having trained and raced in the Gravity trainers for the season I am now planning slower longer base mile runs over the winter. These Isaac “Guidance trainers” work very well both for Newton newbies as well as for slower training runs where the original Gravity trainers are a bit too unforgiving (especially semi off-road conditions). The more supportive heel plus redesigned “actuator lugs” give a more forgiving feel but still have the Newton feel. Overall very impressed and a great addition to the Newton range.

Posted by Car - 12/01/2009 07:29 PM

I really do not understand how a shoe can be suitable for any kind of gait. How anybody with low arch/flat feet use it? How does it feel? I’m trying to decide between this new version or the trainer stability (


Posted by Brian - 03/09/2010 11:49 PM

I’m into my second pair of Newtons. The first were great and I wore them out pretty quickly. The second pair, which were exactly the same model and size as the first, didn’t quite do it for me for some reason. Might have come from a bad lot at the factory.. who knows? I’m very interested in the Sir Isaac and will probably head over to Roadrunner Sports next week to take a test run. So far, I’m impressed with Newton shoes. P.S., I’m also a pronator by the way but have never had any problems with the Newton brand or the running style.

Posted by Marc the Shark - 07/03/2010 11:16 AM

How do the Newtons compare to Asics in terms of comfort and cushioning, anybody know? I am a die-hard Asics guy, and I am so tempted to try the Newtons but wondering if the actuator lugs really do anything and if the shoes are as soft and nice on the feet as Asics gel. Thanks for any and all feedback.

Posted by betsy Gmerek - 08/23/2010 01:37 AM

Well, I bought the Lady Isaacs newtons n ($149) with actuator lugs about two weeks ago (I am a fore foot runner, varsity compettive runner in collere and have been running for last 25 years since) and do lots of hills, usually p[avement 5-8 mile runs 4-5 times a week at a 7-8 min mile pace. Well, after ONE run in these new shoes (which felt great for me!)the sole lug was worn completley down flat/bare on the left foot! I reported this to roadrunner where I purchased them and to newton. I love them so I was extremely shocked and disappointed in this unexceptable wear on sole, unlike I have hever experienced in a vaireyt of running shoes. ODD? Not sure what to replace them with? betsy

Posted by MensTrainers - 10/19/2010 02:23 AM

i didn’t have a chance to get some over-the-knee boots last season, so I’m saving up to make that purchase this year! Love the choices in every category!

this shoes is very tren and very2 good

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