More Sugar More Pain?

Many patients tell me they have a high threshold for pain. Until I start to work on them. Then they change their mind (not everyone of course).

Being in the pain business (i.e. finding the cause of patients' pain and treating it), I've always been intrigued about how we tolerate pain. Some patients can definitely tolerate pain better than others.

The article referenced below (Ye et al, 2022) definitely caught my eye. The researchers investigated the effects of high blood sugar on pain sensitivity and pain inhibition (the act of stopping or slowing down pain) in healthy adults with normal and excess body fat.

The researchers found that ingesting just 75 grams of glucose (2 standard cans of soft drink) in the overweight group of subjects caused the subjects more pain when both their feet were submerged in cold water for 1 minute.

In addition, having acute hyperglycaemia (high blood sugar levels) also suppressed resting heart rate variablity (HRV) in the group with excess fat mass. *HRV is where the amount of time between your heart beats fluctates slightly.These fluctuations can indicated current or future health problems like heart conditions or anxiety and depression.

Regardless of blood sugar levels, the group with excess fat mass could not tolerate the pain from a pin prick after cold water immersion. This group also reported higher pain levels during a 5-minute period of blood flow occlusion.

In addition to the effects of high blood sugar on pain sensitivity and pain inhibition, effects on HRV and reactive hyperaemia (increase of blood flow) after arterial occlusion were also investigated. Both high blood sugar and excess body fat affected HRV and reactive hyperaemia only in people with extra fat mass.

Interpreted together, the researchers concluded that high blood sugar levels affected pain processing levels and autonomic function, especially in people with excess body fat mass. 

So, if you are overweight and consume more than 75 grams of sugar (2 standard cans of soft drinks) you will more likely feel more pain compared to someone who is not overweight.

The authors added that since both hyperglycaemia (high blood sugar levels) and being overweight are risk factors for diabetes, further research should be done on whether and how these sources of pain affects people with diabetes.

Reference

Ye D, Fairchild TJ, Vo L et al (2022). High Blood Glucose And Excess Body Fat Enhance Pain Sensitivity And Weaken Pain Inhibition In Healthy Adults: A Single-blind And Cross-over Randomised Controlled Trial. J of Pain. In Press, published 16 Sep 2022. DOI: 10.1016/j.pain.2022.09.006

*HRV responds uniquely for everyone. As a rule of thumb, values under 50 ms are unhealthy, 50-100 ms signal compromised health and readings above 100 ms are healthy.

How Accurate Is Your Smart Watch?

I have noticed almost all my patients wear a smart watch now. Mostly an Apple watch. Actually, Aized recently has a patient who wears a Rolex on his left hand and an Apple watch on his right. He says he is a watch connoisseur (hence the Rolex), but the Apple watch is more practical since it monitors his health, allows him to read his whatsapp messages, email and also to make payments easily.

Are the readings for heart rate, calories used and energy expenditure accurate? Definitely more so if you have updated personalized metrics like your weight, height, age and gender to make the calorie estimates more accurate. That was what I thought until I looked it up.

I found a study that studied the heart rate and energy expenditure accuracy of the Apple watch, Fitbit Charge HR and Garmin Forerunner 225. All the watches overestimated energy expenditure. 

Another study looked at the Apple watch, Samsung Gear 2, Basis Peak, Fitbit Surge, Microsoft Band, Mio Alpha 2 and the PulseOn. That study found that even though heart rate was adequately measured, energy expenditure was not.

A third study concluded that 2 fitness watches (Polar V800, Garmin Forerunner 920XT) and 3 activity trackers (Garmin vivosmart@HR, TomTom Touch and Withings pulse Ox) were not accurate enough to be used for sports or heathcare applications. Ouch! And I thought Polar and Garmin are the market leaders for sports watches. No prizes for guessing when measuring distances and altitude gain then.

The quality of heart rate data reading can affect accuracy. Compared to using a chest strap to measuring your heart rate with having an Apple watch on your wrist, the chest strap will be more accurate.

According to Apple, how snugly the watch fits against your skin, the surrounding temperature and tattoos can affect readings. The ink, pattern and saturation of some tattoos can block light from the sensor, affecting the reliability of readings. 

Yes, you read correctly, tattoos can affect your sporting performance as we have written before. 

Note that all the 3 studies had less than 100 participants each and technology for such watches and activity trackers are consistenly improving so the latest versions can be more accurate. For now, bear in mind that the readings are just an estimate.

References

Dooley EE, Golaszewski NM and Bartholomew JB (2017). Estimating Accuracy At Exercise Intensities: A Comparative Study Of Self-monitoring Heart Rate And Physical Activity Wearable Devices. MMIR Mhealth Uhealth. 5(3): e34. DOI: 10.2196/mhealth.7043

Passhler S, Bohrer J, Blochinger L et al (2019). Validity Of Wrist-worn Activity Trackers For Estimating VO2 Max and Energy Expenditure. Int J Environ Res Public Health 16(17), 3037. DOI: 10.3390/ijerph16173037

Shcherbina A, Mattsson CM, Waggott D et al (2017). Accuracy in Wrist-worn, Sensor-based Measurements Of Heart Rate And Energy Expenditure In A Diverse Cohort. J pers Med. 7(2): 3. DOI: 10.3390/jpm7020003

Team Building This Quarter

Our 3rd team building session for the year. One every quarter so far this year. We went to Ves Studio to learn pottery. We had great fun with Jeanette Wee teaching us. 

Jeanette is the real master here

Our hand skills in treating patients did not translate the same way however. 

Our craft

Stay tuned for the next team building session.

Group photo

Deltoid Ligament Sprain? No! It's the Tibialis Posterior

R tibilais posterior

A patient who came in to see me yesterday was diagnosed with a deltoid ligament sprain in his left ankle. He had seen a doctor who referred him to a surgeon. An MRI was ordered, but all came back normal. The surgeon referred him for physiotherapy to treat his deltoid ligament.

L deltoid ligament from Dr R LaPrade JBJS

Here's what the patient told me. He was training for the Ironman 70.3 triathlon in Cebu, Philippines on August 7th, 2022. He had done a lot of  *'brick' training prior to the pain in his left ankle. Triathletes will know that *'brick' workouts are cycling followed by running straight after dismounting to simulate race conditions. One day before the race he felt a sharp left calf pain. As a result, he had to walk the whole run (21.1 km) during his race. Thereafter, after returning to Singapore, the inside part of his left ankle started hurting.

I assessed his ankle joint and his ankle proproception and both were good. No tenderness over the deltoid (inner) and outer ankle ligaments. There was however some tenderness behind his left medial malleolus (that bone sticking out at the inside ankle region) and definitely along his tibalis posterior muscle. Much more than his right ride. 

Single-leg heel raise (SLHR) test ability on the left elicited pain too. Bingo! For the physiotherapists and clinicians reading this, you may already know what is wrong with my patient. He had a problem with his left tibialis posterior. Yes, the same tibialis posterior muscle that can cause the dreaded shin splints and your arches to "collapse". Definitely not a deltoid ligament sprain in his case.

The SLHR test was described by a study (Ross et al, 2021) as one of 4 clinical tests to find out if a patient has tibialis posterior tendinopathy. The other 3 are; pain on tendon palpation, swelling around the tendon and pain and/or weakness with tibialis posterior muscle contraction.

My patient was happy to know that he can resume running after I treated him. 

Reference

Ross, MH, Smith MD, Mellor R  et al (2021). Clinical Tests Of Tibilailis Posterior Tendinopathy: Are They Reliable, And How Are They Reflected In Structural Changes On Imaging? J Orthop Sports Phys Ther. 51(5): 253-260. DOI: 10.2519/jospt.2019.9707

Picture by Ezisports.com.au

*Brick training- short form for bike-run-in-combination. Perhaps also because it was name after a world champion duathlete and surgeon Dr Matt Brick who came up with the term whem he described his bike-run and run-bike training sessions while training for a duathlon race

The Larger The Disc Injury The More Likely To Heal Without Surgery

Picture from article referenced below

I saw a few patients with slipped discs this past week. Most patients are still very fearful even if their 'slipped discs' happened years ago. They will complain that they have been having back problems ever since.

Having written previously about how 'slipped discs' can heal I will share with my patients the facts about how the larger the disc injury, the more likely it can heal without surgery.

The picture above shows the diffferent types of herniated disc, bulging being the mildest and sequestration the most severe.

When there is a lumbar disc herniation, there is a tear or damage to the outer layers (annulus fibrosus) leading to leakage (or herniation) of the soft, gel-like inside material (nucleus pulposus). This leakage may touch or compress (irritate) the spinal nerves which causes an inflammatory response. This results in the patient complaining of pain, sensations of numbness, tingling sensations down their leg and sometimes neurological dysfunction.

Conservative management for 6 weeks (instead of surgical management) is usually the first choice for  newly diagnosed patients. In some patients, spontaneous reabsorption of the disc herniation is a widely recognized clinical observation. The spontaneous shrinkage or disapperance of a herniated lumbar intervertebral disc without surgery is called reabsorption or resorption.

The biological mechanisms involved in herniated disc resorption includes macrophage infiltration, matrix remodelling and neovascularization.

Since our immune system recognizes the gel leakage as 'foreigners' in our vertebral epidural space, this triggers a casade of inflammatory responses including phagocytosis of inflammatory cells, enzymatic degradation, increased inflammatory mediators. All of which means that healing is taking place. As the herniation decreases after resorption, the clinical symptoms also improve.

The type and composition of the herniated disc may predict the possibility of natural resorption. Extrusion and sequestration have a higher chance for resorption since the leakage is in the epidural space, creating favorable conditions for macrophage infiltration and neovascularization.

Picture from Radiopaedia

However if the area of the spine shows Modic changes, it is not conducive to macrophage infiltration and ingrowth of blood vessels, thus preventing resorption. Modic changes in the spine occur in response to degenerative changes of the discs, pathology or infections. 

An earlier meta-analysis of 38 clinical studies done in 2015 showed that resorption of lumbar disc herniation was as high as 62-66 percent (Chiu et al, 2015).

Further research is ongoing to understand what conditions can induce or promote the reabsorbtion of 'slipped discs'. This will help clinicians to rationally formulate treatment plans for patients.

Today is exactly one year on from my 2nd bike accident. Not the kind of anniversary I like to remember but it does mean that I've come quite a bit further than where I was. Of course I'm still not working the hours I did before the accident, but definitely much more than just after the accident. So I'm testimony that you can definitely recover, even after 2 compression fractures in my spine! 

References

Chiu CC, Chuang TV, Chang KH et al (2015). The Probability Of Spontaneous Regression Of Lumbar Herniated Disc: A Systematic Review. Clic Rehabil. 29(2): 184-195. DOI:10.118/269215514540919.

Yu P, Mao F, Chen J et al (2022). Characteristics And Mechanisms Of Resorption In Lumbar Disc Herniation. Arthritis Res Ther. 24, 205. DOI: 10.1186/s13075-022-02894-8

A meta-analysis of 38 clinical studies done in 2015 showed that resorption of lumbar disc herniation was as high as 62-66 percent.