Physical Therapists Using Clinical Analysis To Discuss The Art And Science Behind Running and The Stuff We Put On Our Feet

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Saucony Endorphin Shift 2 Review - Guest Team
By Contributors Andrea Myers and Ryan Flugaur

Saucony has made some subtle, but important updates in the Endorphin Shift 2. Saucony categorizes this shoe as “structured cushioning,” which makes for an interesting and unique ride. I originally bought the Shift v1 back in 2020, but found them so uncomfortable after a short run (too firm and caused severe pain at the 5th MTP/outside ball of foot) that I returned them. I was a little unsure about testing the 2, but have found it to be a very nice addition to my rotation of neutral footwear.|

Editor's Note: The following review is a follow-up to our original Shift 2 review featuring thoughts from our new reviewers! Click here to see the original Shift 2 review.

Saucony Endorphin Shift 2 lateral side view. Mild checker pattern through heel and thinly through midfoot.
Specifications for the Saucony Endorphin Shift 2 (via Saucony)
Weight: Women’s 9.2oz/Men’s 10.4oz (253g/296g)
Stack height: 38mm heel/34mm forefoot
Drop: 4mm
Classification: Structured cushioning


Andrea: The Shift 2 is unique as a firmer, high stack, 4mm drop shoe. The Speedroll technology (ankle rocker and toe spring) contributes to an incredibly smooth ride. The fit has been improved from the original, with a thinner heel counter, thinner and more breathable mesh upper, and updated anti-slip laces. This shoe will work best for runners with neutral mechanics who would benefit from the Shift’s mild stability features. Runners who are accustomed to 8-12mm drop shoes will notice the difference in drop, and should proceed carefully if purchasing the Shift 2 to avoid injury.


Andrea: I size up ½ size in the entire Endorphin line and was very pleased with the fit of my women’s size 10. The length gave my big toe plenty of room and the width was sufficient to allow a little toe splay. As I have found with the entire Endorphin line, the fit of a size 10 feels exactly the same as the fit of a 9.5 in their non-Endorphin shoes. I tend to dislike shoes for two main reasons: rubbing on the inside of my big toe, and pinching/burning pain at my 5th MTP/outside ball of foot. As I mentioned above, I had horrible burning pain at both 5th MTPs with the original Shift, so I did my first run in the Shift 2 on the treadmill so I could switch shoes if needed. I was very pleasantly surprised by the Shift 2. I noticed two improvements immediately: the 2 is a little softer than the original, and the mesh felt like it stretched a little to give the outside of my foot a little more room. The external heel counter is pretty rigid, but only present around the lower part of the heel. Internally, the heel counter is soft and on the thin side. I did not notice the heel counter at all and experienced no heel slippage. The tongue is gusseted and the laces are an appropriate length and stay in place. Overall, the shoe has a very secure, locked in feel, without being restrictive.

Ryan: I was super excited to try out the Saucony Endorphin Shift 2 since the high review Matt and Nate gave it. However, after my time with the Shift 2, my experience was a little bit different. When first putting on my normal Men’s size 9, I could instantly tell that something was off. The mesh upper provided good support but felt a bit too restrictive especially on the dorsum of the foot, near the big toe. I would say my foot is fairly normal in terms of width. I have noticed a few shoes were a tad snug in the toe box but they stretched out after the first few miles. This was not the case with Shift 2, even after 40 miles, my toes continued to feel cramped. The length of the shoe fit well for me as I had a thumb nail space between my big toe and the edge of the shoe. The external heel counter was barely noticeable but still provided a good heel lock. The tongue is lightly padded and stays in place well. I really enjoyed the cushioning of the heel and had no problems with the width there.

Editors Note: Please check out our original review of the Shift 2 for more fit thoughts.


Andrea: The ride of the Shift 2 for me is best described as running with light guide rails. I typically do not like stability features in shoes, but I actually found that these shoes helped me to not land as severely on the lateral aspect of my midfoot. The 4mm stack combined with the heel bevel and toe spring produce a very smooth and centered feel from initial contact to push off. These shoes were most enjoyable the day after a race or hard workout because of the feeling of guidance and cushioning. I was aware of the weight of the Shift 2 (9.2oz compared with 7.8oz of my go-to trainer, the New Balance Beacon v3), but I found the increased weight an acceptable trade off for the increased comfort and stability. The cushioning in the Speed 2 feels dense and not bouncy. There is very little ground feel in these shoes, which make them nice for tired feet and legs. I did 5 miles in them on a dirt/gravel rail trail, and definitely did not feel the sharper rocks like I would in a lower stack shoe. I would use these shoes primarily for easy runs due to the weight, but they certainly could be used for tempo runs for someone looking for a little more cushioning and stability. I definitely prefer the Endorphin Speed for tempo runs and faster intervals due to the lighter weight and greater responsiveness. There is no visible wear on the sole after 40 miles and I expect these to be 300+ mile shoes.

Ryan: The fit of the Saucony Shift 2 definitely affected the performance of the shoe for me. By mile 2 on my first run, the toes on my right foot began to go numb. This made for a very uncomfortable first run. On subsequent runs, I tried loosening the laces and switched to a bungee lace to test if it would help with the numbness and discomfort. I was able to relieve some of the numbness I was experiencing but the lacing modification did nothing to help with the discomfort of the shoe. Most of the discomfort I was experiencing came from the stitching and the checkered overlay of the shoe. The material used in the checkered pattern is different from the upper and does not allow for much stretch. For some people, this will add to stability in the forefoot but for me it just made it uncomfortable. Despite the discomfort I had with the Saucony Shift 2, there were many things I enjoyed and I feel it could still be a good pick for many runners

I mainly ran in the Shift 2 during my recovery pace and longer mile runs and it held up nicely during those paces. The PWRRUN midsole has a firm feel but when paired with the shoe rocker it makes a smooth transition from midfoot to forefoot. I was a little worried about the 4 mm drop, but when combined with the speedroll technology, the low drop was barely noticeable. From initial contact to toe off, the Shift 2 does a great job progressing through the heel, ankle, foot rockers making the ride feel natural and smooth.


Andrea: The best way to describe the stability of the Shift 2 is centered. While there are no traditional stability features, the heel and forefoot rockers and external heel counter provide some guidance that will work for runners with neutral mechanics or mild stability needs. The heel counter extends fairly far forward (towards the toes) both medially and laterally, providing neutral stabilization without guiding the rearfoot excessively in either direction. The checkered overlays in the upper also help keep the foot centered in the shoe without feeling rigid or restrictive. There is also both medial and lateral sole flare in the rearfoot and forefoot, which also contributes to the shoe’s centered ride.

The Saucony Endorphin Shift 2 is a structured shoe and it does an amazing job of doing just that. This is a shoe that both neutral runners as well as those that need a small amount of guidance can rely on to give them some support. The structure offered in the forefoot and heel may just be too much for my needs.


On Proprioception, by Andrea Myers
At the end of my first run in the Shift 2 on the treadmill, I switched over to my Beacons for comparison. I was surprised at how much more I could feel in the Beacons as compared to the Shift 2. The Beacons have a 30mm/24mm stack as compared to the 38mm/34mm of the Shift 2. As I put more miles on the Shift, I was acutely aware of how little of the ground I could feel. This is a positive when your feet or legs are tired, but it made me consider what the implications of decreased proprioception could be during running.

Proprioception was originally defined by neurophysiologist Charles Sherrington as “the perception of joint and body movement as well as position of the body, or body segments, in space.” (Han et al 2016). It is well established in the scientific literature that improving proprioception can reduce both lower extremity injury risk as well as reduce pain in people who have knee osteoarthritis (Jeong et al 2019). Other researchers have concluded that improving proprioception may reduce ankle injuries in basketball players (Payne et al 1997) and improve global knee function after ACL reconstruction (Risberg et al 2007).

DOR Contributor Peanut (a dog) seen with a BOSU.
Does a shoe that reduces a runner’s proprioceptive input also put that runner at greater risk of injury? I was unable to find any studies that directly examine this topic, likely because it would be extremely difficult to isolate proprioceptive input from a shoe as an independent variable during running. I may indirectly attempt to answer this question by looking at the effect of midsole thickness on running kinematics. A French study tested runners in 0mm heel-toe drop shoes that only varied in midsole thickness: 0mm, 2mm, 4mm, 8mm, and 16mm (Chambon et al 2014). They found that the only gait parameter that varied between test conditions was stance phase duration. The authors stated that this may be due to the shoes with thicker midsole condition (8 and 16mm) being less stiff than the 0-4mm midsole shoes. A different study examined runners in 4mm heel-toe drop shoes that varied in midsole thickness: 4mm heel/0mm forefoot, 12mm/8mm, and 20/16mm (Hamill et al 2011). They also included a test condition in which the runners ran barefoot. They found no differences in impact characteristics between the three shoe conditions, but did find differences between all shoe conditions and the barefoot condition. They stated that the differences were likely due to the runners adapting a midfoot strike pattern when running barefoot as compared to a heel strike pattern in all three shoes.

Sometimes a conclusion that appears logical is not supported by scientific data. I may feel less sensory input when running in a high stack shoe like the Shift, but current scientific evidence does not suggest this will increase my risk of injury. However, current scientific evidence greatly supports athletes including proprioceptive training as part of a comprehensive exercise program to reduce injury risk. Such a program may include exercises on a BOSU, slant board, or balance disc. I would recommend consulting your favorite orthopedic physical therapist for instruction in such a program.

Hee Seong Jeong, Sung-Cheol Lee, Hyunseok Jee, Jun Bom Song, Hyun Sik Chang, Sae Yong Lee; Proprioceptive Training and Outcomes of Patients With Knee Osteoarthritis: A Meta-Analysis of Randomized Controlled Trials. J Athl Train 2 April 2019; 54 (4): 418–428. doi:

Han, J., Waddington, G., Adams, R., Anson, J., & Liu, Y. (2016). Assessing proprioception: A critical review of methods. Journal of sport and health science, 5(1), 80–90.

Payne, K. A., Berg, K., & Latin, R. W. (1997). Ankle injuries and ankle strength, flexibility, and proprioception in college basketball players. Journal of athletic training, 32(3), 221–225.

May Arna Risberg, Inger Holm, Grethe Myklebust, Lars Engebretsen, Neuromuscular Training Versus Strength Training During First 6 Months After Anterior Cruciate Ligament Reconstruction: A Randomized Clinical Trial, Physical Therapy, Volume 87, Issue 6, 1 June 2007, Pages 737–750,

Chambon N., Delattre N., Gu├ęguen N., Berton E., Rao G. (2014) Is midsole thickness a key parameter for the running pattern? Gait Posture 40, 58-63.

Hamill, Joseph & Russell, Elizabeth & Gruber, Allison & Miller, Ross. (2011). Impact characteristics in shod and barefoot running. Footwear Science. 3. 33-40. 10.1080/19424280.2010.542187.

On Numbness and the Importance of Fit, by Ryan Flugaur
During my experience with the Shift 2 I experienced numbness in my foot. I want to discuss why this may happen in a runner. Numbness in the foot or toes when running can be caused by a large number of factors. These include an injury to a different part of the body, poor running mechanics, and possibly poor fitting footwear. In my case when running in the Saucony Endorphin Shift 2, I believe that the footwear was the main contributor. There are bundles of nerves located throughout the foot that transmit signals from the brain to the toes. When that connection is disrupted, the individual may experience numbness as well as possible muscle weakness. Switching up the laces to a bungee lace or skipping lace eyelets may also help to relieve pressure on the nerve and eliminate the numbness.

The tarsal tunnel is also another more common area of nerve impingement in runners which can lead to numbness over the lateral foot and ankle. The tibial nerve runs through the tarsal tunnel on the lateral side of the ankle as well as the tibialis posterior, flexor hallucis longus, flexor digitorum longus, and the posterior tibial artery. Swelling or inflammation to any of these structures can increase the pressure in the tarsal tunnel causing compression on the tibial nerve with possible pain and numbness. This can sometimes lead to what clinicians call tarsal tunnel syndrome. Many times physical therapy is able to treat these injuries conservatively through an exercise program and activity modification.

In the clinic, I have seen patients have numbness in their feet or legs while running due to other various injuries such as a herniated disk or poor pelvic stability. If changing the lace system or going up a shoe size does not correct the problem, having a physical therapist trained in running biomechanics take a look may be able help you diagnose the problem.

McKean KA. Neurologic running injuries. Neurol Clin. 2008 Feb;26(1) 281-96; xii. doi:10.1016/j.ncl.2007.11.007. PMID: 18295096.


Andrea: Overall, I was very happy with the updates to the Shift 2. I would recommend that Saucony standardize their sizing between the Endorphin line and the rest of their footwear. I would also recommend keeping the slightly softer midsole of the 2 for future updates (and not go back to the original).

I feel the toe box and vamp of the shoe could be a bit wider or the material used in the checkered pattern be more flexible. Going up a ½ size may also eliminate the problems I am experiencing.


Andrea: The Saucony Endorphin Shift 2 is a neutral, cushioned trainer that has non-traditional stability features that will work for runners with mild stability needs. It is best for easy miles, but runners who do not mind the extra weight will like it for tempo runs.

The Shift 2 is a shoe that will work well for neutral runners as well as those that need some light guidance. It performs well in a variety of paces ranging from slower recovery runs to a tempo workout. If an individual is in-between shoe sizes or prefers more space in the forefoot, I would suggest going up a ½ size to ensure adequate space in the toe box.


Fit: B+ (fit is perfect except I have to go up ½ size from other Sauconys)
Performance: A-
(protective, smooth neutral trainer)
Stability: A
(non traditional stability features result in a smooth ride)
DPT/Footwear Science: A-
(thick midsole reduces proprioception which some runners may not like, although the evidence does not indicate this will increase injury risk)
Personal: A
(love the updates of the 2!)
Overall: A
(durable, comfortable trainer that provides mild stability and guidance during easy and uptempo runs)

Fit: C (The toe box and vamp was much too restrictive for me despite modifications I made.)
Performance: A- (Smooth transition from initial contact to push off, great high mileage shoe)
Stability: A (One of my favorite parts of the shoe. The structure of the shoe will provide the guidance needed for many runners)
DPT/Footwear Science: A- (Saucony is able to create structural support through a variety of measures that combine nicely to create a smooth ride.)
Personal: B- (I think going up a ½ size would have eliminated many of the problems I had with the forefoot and toe box.)
Overall: B (Despite my problems with the toe box, I still decided to give this shoe a B since its performance and structural stability are going to be great for a large percentage of runners )


Visit Running Warehouse here to purchase the Endorphin Shift 2. Using the link helps support Doctors of Running. Thank you so much!

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Dr. Andrea Myers is a Doctor of Physical Therapy and Board Certified Orthopedic Specialist who sees patients in Bethel, CT at Carlson ProCare. She also provides bike fitting services at Class Cycles in Southbury, CT. Andrea completed her undergraduate degree in molecular and cellular biology at the University of Illinois at Urbana-Champaign. She graduated from St. Ambrose University in 2006 with a Doctorate in Physical Therapy.

Dr. Andrea Myers is a 5’7”, 130 pound female with PRs of 3:04:48 for the marathon and 18:41 for the 5k. She typically runs 35-60 miles per week with recovery runs at 8:00-8:30/mi pace and 5:30/mi pace for shorter efforts. She prefers firmer, neutral shoes with 4-8mm of drop and high volume toe boxes. IG handle: dreamy560

Dr. Ryan Flugaur is a Doctor of Physical Therapy at Point Forward Physical Therapy in Stevens Point, WI. He works with variety of orthopedic conditions but specializes in treating injured athletes including runners, throwers, and swimmers. Dr. Flugaur graduated from the University of Wisconsin- Stevens Point with a bachelor’s degree in biology. He attained his doctorate from Concordia University Wisconsin. Since becoming a physical therapist, Dr Flugaur has completed advanced training through the Movement Performance Institute in advanced biomechanics of running, Washington University (St. Louis) in movement system impairment syndromes, and the Titleist Performance Institute in golfing biomechanics.

PRs Include: 5K:20:05 (2021) 10 K: 43:36 (2021) Half-Marathon 1:42:22 (2021)

Editor's Note: As always, the views presented on this website belong to myself or the selected few who contribute to these posts. This website should not and does not serve as a replacement for seeking medical care. If you are currently injured or concerned about an injury, please see your
local running physical therapist. If you are in the Los Angeles area, I am currently taking clients for running evaluations.

***Disclaimer: These shoes were provided free of charge in exchange for a review.  We thank the  people at Saucony for sending us a pair.  This in no way affected the honesty of this review. We systematically put each type of shoe through certain runs prior to review. For trainers and performance trainers, we take them on daily runs, workouts, recovery runs and a long run prior to review (often accumulating anywhere from 20-50 miles in the process). For racing flats we ensure that we have completed intervals, a tempo or steady state run run as well as a warm up and cool down in each pair prior to review. This systematic process is to ensure that we have experience with each shoe in a large variety of conditions to provide expansive and thorough reviews for the public and for companies. Our views are based on our extensive history in the footwear industry and years testing and developing footwear. If you are a footwear rep looking for footwear reviews or consultations on development, we are currently looking to partner with companies to assist, discuss and promote footwear models. Partnership will not affect the honesty of our reviews.

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