Tuesday, February 25, 2020

Thinking Of Changing To Maximalist Running Shoes?

Picture from Nike
I received an email recently on what shoes top Japanese runners want to be wearing. I'm sure not only the top Japanese runners want the shoe, I bet all the top runners in the world would dearly love to get a pair of Nike's Vaporfly.

Better still if they can get a pair Kipchoge's prototype shoe dubbed the Alphafly that he wore during the sub 2 hour marathon in Vienna.
Picture from Nike
Consider Reid Coolsaet, a 2-time Canadian Olympic marathoner who let his shoe contract with New Balance expire in 2019 so he can use the Nike Vaporfly to try and qualify for a third Olympics. He has been sponsored by New Balance and wearing their running shoes since 2008.

If you compete in running races or support your friends or loved one at their races you will surely notice that ultra thick, super cushioned shoes are quite the norm now. This is different from the minimalistbarefoot style shoes that were popular just a few years ago.

Some runners definitely got hurt wearing the barely there, minimalist type running shoes, while others did not like the skimpy feel which probably contributed to the wide swing towards the maximalist  running shoes that are popular now.

Running in these thickly cushioned shoes can affect running form in surprising ways as found by researchers on recreational athletes. As I wrote before in a previous post, these recreational runners pound harder and pronate more in thickly cushioned shoes compared to standard running shoes (Pollard et al, 2018).

In a follow up study to Pollard et al's study (2018), the researchers had the runners run in the maximalist shoes for six weeks (so the runners get used to them) before they repeated the testing.

The runners somehow did not adjust to the shoes. Interestingly, the runners still landed with greater force and pronated more in the maximalist shoes compared to their initial test run (Hannigan and Pollard, 2019).

There was a yet another follow up study which was just published last month on a new group of male and female recreational runners (Hannigan and Pollard, 2020). The researchers got New Balance to custom make a pair of their neutral running shoes to allow them to alter the shoe by adding or removing foam. This shoe can then serve as minimalist, traditional or maximalist shoes to allow the researchers to focus solely on the role of cushioning in the runners' form.

This time, a few of the runners in this study were found to land heavily in the minimalist and maximalist shoes, but they pronated most in the maximalist shoes.

The authors commented that looking at the three studies as a whole would suggest that extra cushioning does influence several aspects of the way we run. The thickly stacked soles of maximalist shoes seem to subtly affect balance, making the shoe more unstable. This is then likely to increase ankle movement and pronation.

With the extra layers of foam, it also affects the way our legs feel the ground when we land. This affects our muscles, brains and our nervous system in coordinating and anticipating foot fall when we walk or run.

Points to note are the researchers did not look at how fast the runners ran nor did they ask how the runners felt in the maximalist shoes. They also did not track actual running injuries in the runners studied so they cannot say if the extra cushioning contributes to or reduces injury.

Even though I have treated runners who have gotten seriously injured while wearing maximalist running shoes, I'm definitely not against any runners switching to them. Provided they have tested them and ease into training with them slowly and finding them suitable.

Reading the 3 articles and interpreting their results has made me wonder if the thicker soled models are right for recreational runners since comfort and injury risks are different compared to elite runners.


*Note -In the 2018 and 2019 running studies, the runners wore Hoka running shoes and not the Nike Vaporfly.

References

Hannigan JJ and Pollard CD (2019). A 6-Week Transition To Maximal Running Shoes Does Not Change Running Biomechanics. AJSM. 47(4): 968-973. DOI: 10.1177/0363546519826086.

Hannigan JJ and Pollard CD (2020). Differences In Running Biomechanics Between A Maximal, Traditional And Minimal Running Shoe. J Sci Med Sp. 23(1): 15-19. DOI: 10.1016/j.jsams.2019.08.008

Pollard CD Ter Har JA et al (2018). Influence Of Maximal Running Shoes On Biomechanics Before And After A 5k Run. Orth J Sp Med. 6(6): 2325967118775720. DOI: 10.1177/2325967118775720.

Monday, February 17, 2020

Who Says Your Knees Cannot Come Forward When You Squat

Rachel squatting forward with her knees over toes
For almost as long as I have been working as a physiotherapist (> 20 years), I have often heard other physiotherapists, trainers, strength and conditioning coaches tell patients that it's wrong to let their knees come forward when performing a squat. That by doing so, they will damage their knees. In fact, I've had many arguments/ disagreements with my ex colleagues at Sport Singapore (formerly Singapore Sports Council) regarding this.

To which I say that it's one of the biggest training myths ever. Yes, that your knees should not travel forward past the toes during a squat is definitely a myth.

In a study by Fry et al (2003), the authors looked at how joint forces at the knees and hips changed when restricting forward knee movement during a squat. What the authors found was that squatting with restricted forward knee movement showed a 22% decrease in knee forces while increasing hip forces by 1070%!
Picture A- knee travels forward, B restricted knee movement
Hence, you're simply shifting the load from the knees to the hips and lower back when you restrict forward movement of the knee. This is a lot more work for your hips and back to absorb and is potentially more dangerous for your hip and back.

Yes, I do agree it's true that it does stress your knees more when you allow your knees to come forward while squatting. However, this is well within the normal limits of what the knees can handle (Schoenfeld 2010).

You go to any Crossfit gym and/ or watch any  Olympic weight lifters and you will see that in order to reach full depth in the squat, their knees will almost always have to go forward past the toes (see picture below). The Olympic weight lifters will often do that with very high loads too.
Picture from Irving Henson taken at The Pit
If you stick your bum out when you squat, you are engaging more of your bum (Gluteus Maximus) muscles. If your let your knees travel forward when you squat, you are definitely using your thigh (Quadriceps) muscles. It just depends on what muscles you want to engage more. Try it yourself.
Different types of squats will have different types of knee forward movement as well. Front squat, high bar back squat, low bar back squat and box squats just to name a few.

So now you know that there is no real need to restrict forward knee movement when you squat, especially if you want to load your quadriceps more. As long as you are not squatting excessively  and with a super heavy load like the Olympic weight lifters.



References

Fry AC, Smith JC and Schilling BK (2003). Effect Of Knee Position On Hip And Knee Torques During The Barbell Squat. J Strength Cond Res. 17(4): 629-633.

Schoenfeld BJ (2010). Squatting Performance And Kinematics And Their Application To Exercise Performance. J Strength Cond Res. 24(12): 3497-3506. DOI: 10.1519/JSC.0b013e3181bac2d7.

Now surely the knees have to come forward .... picture from Catalyst Athletics

Monday, February 10, 2020

Slipped Discs Can Heal

Yes, you read correctly, our intervertebral discs (IVD) can heal after injury! Last week I wrote about how strong our IVD's are and how our discs cannot 'slip' as they are firmly attached to the vertebral end plate by very strong connective tissue. But they can get injured or herniated, especially by shearing forces.
Disc strongly attached to vertebral end plate
You probably will not believe how many times this scenario has happened. A patient coming in to our clinic telling me that they had a 'slipped' disc or "blew out a disc" years ago and have been having back problems since. And I've to go through the following evidence and healing process of our IVD with them.

Since the IVD is part of our human anatomy just like our muscles, nerves, bones, tendons, ligaments etc, the IVD can heal with correct conservative management and time. Consider the following evidence.

Chui et al (2015) did a systematic review of the literature to look for evidence of our lumbar discs healing. Their inclusion criteria was patients who had herniated lumbar discs that were treated conservatively and patients must have at least two imaging evaluations of their lumbar spine.

Patients who had previous lower back surgery, tumours, spinal infections, spondylolistheis and spinal stenosis were excluded from the review. In their systematic review, the authors found 31 studies that fit their criteria.

Their results will definitely surprise you. Here's what the author's wrote. "Spontaneous regression of herniated disc tissue can occur, and can completely resolve after conservative treatment. Patients with disc extrusion and sequestration had a significantly higher possibility of having spontaneous regression than did those with bulging or protruding discs. Disc sequestration had a significantly higher rate of complete regression than dis disc extrusion."

The larger the disc injury, the more likely it is to revert to its former shape and heal! For disc sequestration, rate of spontaneous regression was found to be 96%. For disc extrusion 70%, 41% for disc protrusion and 13% for a disc bulge.

It does seem like (my personal opinion) the more serious the disc injury, the larger response our bodies have for healing.

In another study by Nakashima et al (2015), the authors studied the MRI's of 1211 asymptomatic adults ranging from 20 to 70 years old. They found that 87.6% of subjects presented with disc bulges, and this significantly increased with age in terms of frequency.

Even most of the subjects in the 20's had bulging discs, 73.3% of males and 78% of females respectively. The authors concluded that disc bulging was frequently observed in asymptomatic subjects including those in their 20's.

It is my hope that after reading this, patients who have been told that they have on their MRI 'slip' discs, herniated discs etc will have new found knowledge and confidence that they can definitely get better with conservative management and not require surgery.

If the healthcare professional treating your 'slip disc' tells you you need surgery, you can show them this article.


References

Chui CC, Chuang TY et al (2015). The Probability Of Spontaneous Regression Of Lumbar Herniated Disc: A Systematic Review. Clin Rehabil. 29(2); 184-195. DOI: 10.1177/0269215514540919

Nakashima H, Yukawa Y et al (2015). Abnormal Findings On Magentic Resonance Images Of The Cervical Spines In 1211 Asymptomatic Subjects. Spine. 40(6): 392-398. DOI: 10.1097/BRS.0000000000000775

Monday, February 3, 2020

What You Need To Know About Slipped Discs


We're still writing about our backs. This week I'm writing about 'slipped discs' in the spine. This is a topic that I get questions from most often among my friends and patients alike.

Patients have always been told that the intervertebral disc (IVD) causes referred pain down the back/ side of your legs. They often think that discs are very fragile and get easily injured.

Almost every single one of my patients are fearful of having a 'slipped intervertebral disc' whenever they have low back pain (LBP). The discs have a really bad reputation for causing significant pain and disability in many people

Are these common beliefs accurate? Let's go through the anatomy of the spine and the IVD.


The IVD consists of a very tough outer layer called the annulus fibrosis (AF). It is made of of several layers of fibrocartilage consisting of Type I and II collagen fibers. The AF protects the soft, gel-like substance in the middle known as the nucleus pulposus (NP). The NP helps distribute pressure evenly across the IVD and prevent excessive forces on the spine.


See how thick the AF is from the picture above? Here's something else you need to know. There is a cartilaginous endplate between the AF and the vertebra (the spine). The endplates hold the IVD in place. It allows load to be spread evenly and to provide attachment to the IVD. This creates a super strong connection to the AF making it impossible for the IVD to 'slip' out of position.

How strong are our IVD's? In a published study on thoracic discs in the young (28 years old plus minus 8 years) , it took about 740 pounds of force to compress the disc height 1 mm. For the older subjects (70 years young plus minus 7 years), it took almost 460 pounds of force. Note that these are on cadavers with the muscles and bones cut away (Stemper et al, 2010).


The endplates also allow for hydration of the disc to take place (see picture above).

Just like your ACL is often injured by shearing forces, it is also shearing forces that is most likely to hurt your discs. Twisting, rotating your back while lifting a heavy load is definitely not recommended.

What happens after your disc is injured? Find out more next week as I write more on that topic.



Reference

Stemper BD, Board D et al (2010). Biomechanical Properties Of Human Thoracic Spine Disc Segments. J Craniovert Junct Sp. 1(1): 18-22. DOI: 10.4103/09774-8237.65477