Sunday, March 17, 2019

High Intensity Interval Training (HIIT) Reduces Cancer Cell Growth?

Picture by richseow from Flickr
I've written positively before about the effects of running on cancer a few years ago. Now there seems to be more evidence that even a single session of high intensity interval training (HIIT) may significantly slow the growth of colon cancer cells.

Researchers had male colorectal cancer survivors perform either a single HIIT session or do HIIT regularly for a month.

After a ten minute warm up, the single HIIT group did four intervals of four minutes cycling (at 85to 95 percent maximum heart rate) with three minutes of recovery in between. The other group did this same session three times a week for a month.

Picture by jungle jim3 from Flickr
Blood samples were taken from these subjects before and after the HIIT sessions. Blood samples before exercise had no effect whatsoever on the cancer cells. Blood samples after the HIIT sessions showed a decrease in the cancer cells immediately.

While comparing the single session HIIT group with the other, there was no significant difference in the blood samples.

During high intensity exercises, our muscles releases lots of myokines (inflammatory cytokines) compared to moderate intensity exercises.

The researchers attributed the cancer cells reduction to cytokines (or inflammatory markers) found in the bloodstream after exercise.

The researchers suggested that the reduction in cancer cells in the colon is not specific to those who had cancer before. Other studies have found similar reductions in prostate cancer cells in healthy individuals as well.

Every individual tolerates and responds differently to exercises, especially HIIT sessions. Train don't strain is important too.


Devin JL, Hill MM et al (2019). Acute High Intensity Interval Exercise Reduces Colon Cancer Cell Growth. J Physiol. DOI: 10.1113/JP277648.

Sunday, March 10, 2019

Autologous Chondrocyte Transplantation For Articular Cartilage Injuries

In the two previous posts, we discussed the microfracture technique and the mosaicplasty technique for articular injuries. The third major procedure for articular cartilage injuries is autologous chondrocyte transplanatation (ACT) or autologous chondrocyte implantation (ACI). This is also the most invasive of the three. This method is usually chosen if the defect is larger than 5 cm and especially if there's a "kissing lesion" (or touching lesions on two joint surfaces).
Kissing lesions- both surfaces affected
The patient undergoes two surgeries for this. In the first, a small patch of healthy articular cartilage the size of one of two Tic Tacs is harvested (from the knee) and sent to a laboratory. It is subsequently grown in a protected medium to get more healthy articular cartilage. During the second surgery two to three weeks later, these newly grown articular cartilage cells are placed onto the defect (which is cleaned) to restore the surface.

There are of course variations to the three surgical interventions described in these few posts like a cell based scaffolding, stem cells etc.

Return to light sporting activities is usually allowed after six months with full return to sports at around nine to twelve months after the second surgery depending on how the patient recovers.

These have strong implications for physiotherapists in the management of these disorders as physiotherapists take charge of the patient's rehabilitation program after surgery. Successful rehabilitation for a patient requires the physiotherapist to have knowledge of the biology of articular cartilage and the factors that will influence damage and repair.

This requires restoring motion and muscle function while reducing functional limitations during weight bearing activities. Patient education and setting of realistic goals based on the extent of the damage is crucial to a successful outcome.

The postoperative management of patient varies according to the surgery performed. There are different time frames for non and partial weight bearing, specific physiotherapy treatment and use of continuous passive motion (CPM) machines. Other than improving range, CPM machines provide a mechanical stimulus to joints to promote healing (Sledge, 2001).

A good surgical technique is only as good as its rehabilitation. Come and see us if you have articular cartilage injuries as we definitely know what to do.


Brittberg M, Lindahl A et al (1994). N Eng J Med. 331(14): 889-95. DOI: 10.1056/NEJM199410063311401.

Vasiliadis HS and Wasiak J (2016). Autologous Chondrocyte Implantation For Full Thickness Articular Cartilage Defects Of The Knee. Cochrane Database of Systematic Reviews. Issue 10. Art. No CD003323. DOI: 10.1002/14651858.CD003323.pub3.

Sledge, SL (2001). Microfracture Techniques In The Treatment Of Osteochondral Injuries. Clinics Sp Med. 20(2): 365-377.

Sunday, March 3, 2019

Mosaicplasty For Articular Cartilage Injuries

Last week we discussed the microfracture technique for articular cartilage injuries. Many of my patients who read the article commented that they did not realize it was such a serious condition. Yes, indeed, having an articular cartilage injury is worse than tearing your anterior cruciate ligament (ACL). The lengthy rehabilitation makes it much worse.

Generally, the microfracture technique works well only for the smaller lesions (less than 3 cm). If the size of the defect is larger, the surgeon would usually perform mosaicplasty or autologous chondrocyte transplantation (ACT). The latter procedure works better if there is a "kissing lesion" (defect on both joint surfaces).

I wrote that the microfracture technique was made popular by Richard Steadman. For mosaicplasty, it is Professor Laszlo Hangody from Hungary who has probably performed the most procedures and published the most articles on the topic.
Harvesting the bone plugs

Mosaicplasty is a technique in which small bone plugs with healthy hyaline cartilage are taken and then transplanted to cover the defect in the damaged area. The bone plugs are usually taken from an area that is non weight bearing to cover the defect in the affected area. The end result ends up looking like mosaic tiles, hence the name mosaicplasty.
Here's a closer look

The hope is that the body will not miss the taken parts and it can be used where it is needed. Over time, the holes in that part of  bone that is taken will fill with bone and scar tissue. The bone plugs can be from the patient or from fresh cadavers.

The above diagram shows the procedure done on a patient's knee, but it can be done on the ankle, hip and other weight bearing articular surfaces too.

A similar technique to mosaicplasty is Osteochondral Autograft Transfer System or (OATS). The bone plugs used in OATS are usually larger and usually only one or two plugs are needed to fill the area of damage.
See the gaps in between the bone plugs?
In the above pictures, you can see that there are still gaps between the cylindrical bone plugs. This is the main problem with this particular technique. The defect is not filled completely and the gaps normally fill up with fibrocartilage. There is then a worry about how this holds up over time, especially if the patient is keen on returning to sports.

Recently, there has been an improvement/ modification to this technique. A group of researchers, inspired by the honey comb structure of a beehive of honey bees decided to use hexagonal shaped bone plugs instead of the cylindrical ones used previously.
No more gaps?
This is to eliminate the gaps while performing the procedure. The authors named it hexagonal osteochondral graft system (HOGS). Early outcomes of HOGS seemed comparable to mosaicplasty and promising at this stage although further follow up needs to be done.

Advantages of mosaicplasty  are that only one operation is needed (compared to two in ACT) and hence lower cost and less down time. There is less risk of disease transmission and there is a high percentage of hyaline cartilage for the damaged surface.

These procedures require the physiotherapist treating the patient to have knowledge of the biology of articular cartilage and the factors that may influence degradation and repair. The physiotherapist needs to know the nature, location, size of lesion and the surgical procedure performed.

Rehabilitation should address the patient's impairments and functional limitations without jeopardizing healing of the lesion.

I remember back in 1999, as a young physiotherapist a patient told me he had mosaicplasty done and I had asked him what it was. That piqued my interest in articular cartilage injuries and especially so when I later had to have a microfracture procedure done on my right knee in 2003. That also was why I did postgraduate work in that area as I desperately wanted to compete again.

My next post will be on the autologous chondrocyte transplantation/ implantation (ACT) procedure.


Erol MF and Karakoyun O. (2016). A New Point Of View For Mosaicplasty In The Treatment Of Focal Cartilage Defects Of Knee Joint: Honeycomb Pattern. SpringerPlus. 5(1): 1170. DOI: 10.1186/s40064-016-2796-y.

Gracitelli GC, Moraes VY et al (2016). Surgical Interventions (Microfracture, Drilling, Mosaicplasty And Allograft Transplantation) For Treating Isolated Cartilage Defects Of The Knee In Adults. Cochrane Database of Systematic Reviews. Issue 9. Art. No CD10675. DOI: 10.1002/4651858.CD010675.pub2.

Hangody L and Balo E (2011). Autologous Osteochondral Mosaicplasty. In Sanchis-Alfonso V. (eds). Anterior Knee Pain And Patellar Instability, London.

Sunday, February 24, 2019

My Patient Had A Microfracture Done In The Knee

Articular cartilage is white, with the bone exposed
A fellow physiotherapist who works in a hospital came to see me after a microfracture procedure done on her knee. There was a grade 4 articular cartilage defect on her knee and this led to swelling and pain while climbing stairs and after weight training.

Outerbridge articular cartilage classification
All of us have a layer of articular cartilage covering the ends of  our bones, especially the joint surfaces. It is normally tough and resilient. This helps to protect the joint during load bearing and reduce friction during movement. Injury or damage to the articular cartilage can result from trauma (during sports) or from daily wear and tear. As articular cartilage has poor/ no blood supply, it does not heal well after injury.

There is no standard and uniform approach to managing articular cartilage injuries in the knee. Left untreated it can progress to significant joint destruction. The patient may then need a total knee replacement in the worse case scenario.

Treatment options include microfracture, arthoscopic drilling, mosaicplasty and chondrocyte transplantation to restore the joint surface.

A microfracture technique is where the surgeon performs key hole surgery to cause bleeding on the bone surface to promote healing (picture below). After the blood clots and heals, a layer of fibrocartilage is formed. This technique was first made popular more than 20 years ago by Dr Richard Steadman from Vail, Colorado who has since retired.

My patient had the microfracture procedure done (in the picture above) and as you can imagine, the rehabilitation to return to sport can be lengthy. There is usually a period of non weight bearing for the first six to eight weeks to allow healing while using continuous passive motion (or CPM) machine at night. Use of the CPM machine is to stimulate movement to enable nutrition in the articular cartilage since the patient is non weight bearing. Yes, correct movement is necessary our articular cartilage.

Most surgeons here do not usually suggest use of the CPM machine after performing the microfracture technique which I feel is critical in order for optimal healing to occur in the articular cartilage.

Lots of patience and consistency are required by the patient and physiotherapist to slowly regain functional range of movement and strength before any return to sport work can be done.

Fortunately, articular cartilage injuries are my area of interest having had them myself (and requiring 3 knee surgeries) and my postgraduate research was in this area.

I'll write more about mosaicplasty and and the chondrocyte transplantation procedure in the next post. Stay tuned.


Hurst JM, Steadman JR et al (2010). Rehabilitation Following Microfracture For Chondral Injury In The Knee. Clin Sports Med. 29(2): 257-265. DOI: 10.1016/j.csm.2009012.009.

Steadmann JR, Rodkey WG et al (1997). Microfracture Technique For Full-thickness Chondral Defects. Oper Tech Orthop. 7:300-304.

Here's what the surgeons use to cause bleeding in the bone

Sunday, February 17, 2019

Is CrossFit Safer Than Running?

Picture by Kylie Siu 
There, I thought that headline will catch your attention. More on that statistic later in the article.

CrossFit comprises of calisthenics, Olympic weightlifting, powerlifting, plyometrics, high intensity interval training (HIIT), gymnastics, running, rowing and other exercises. Participants complete daily WODs (workouts of the day) to build cardiovascular endurance, stamina, strength, flexibility, power, speed, agility etc.

CrossFit Inc was founded by Greg Glassman and Lauren Jenai in 2000 in Santa Cruz, California. It was started earlier as Cross-Fit In 1996. After the couple fell out, Glassman bought over her share with a huge loan.

CrossFit was also made popular by military personnel, law enforcement agencies, fire departments etc who can do WODs anywhere by accessing it online.

I've seen many CrossFit athletes come to our clinic, mostly by word of mouth referral. I'm told by some of them that they like to see me because I don't ask them to stop training as they're often when they see someone else when they have an injury.

Other doctors and other health care practitioners often tell them that CrossFit has a high risk of musculoskeletal injury. I usually allow them to train (modified of course) while getting them better. One such patient asked if I can write about CrossFit injuries.

So here's what I found from published articles. Those of you reading this because of the title, thank you for reading this far.

Most of the research suggest that CrossFit is not more dangerous than other strength based training. like weight or power lifting. Researchers found CrossFit results in roughly 2.1 injuries per 1000 training hours. It was actually higher for endurance sports like running. Recreational running resulted in 8 injuries per 1000 hours of training. For novice runners the figure shot up to 18.

Athletes new to CrossFit (less than 6 months) were definitely injured more often. This finding is important and coaches and athletes need to focus on correct movement patterns. Workouts need to be modified for beginners.

Common injury locations were in the knee, lower back and shoulder. Majority of the injuries were reported as chronic/ overuse in nature. Possible causes included bad/incorrect form to lift a heavier weight, fatigue, old injury and too little/ bad coaching.

Because the WODs were constantly changing and varied, CrossFit athletes are often sore or will have some discomfort from training. This can result in an inability to do the next day's workout fresh, resulting in a higher chance of injury.

Majority of injuries we see in our clinics tend to be chronic/ overuse in nature. They can definitely be remedied by coaches through modification of complexity, volume and intensity of workouts. The healthcare practitioner treating such athletes will need to modify their training around their current injuries. A simple example is an athlete with a Right lower limb injury is still able to continue CrossFit by training the upper body and L lower limb.

Bear in mind that CrossFit for general strength and fitness is different from competing in CrossFit competitions. While competing, you need to go all out with fixed weight and exercises. When performing workouts for general fitness, you can reduce the weight, drop the reps or change to a similar but less technical exercise.


Claudino JG, Bourgeois F et al (2018). CorssFit Overview: Systematic Review And Meta-analysis. Sports Med Open. 4:11. DOI: 10.1186/s40798-018-0124-5.

Mehrab M, De Vos R et al (2017). Injury Incidence And Patterns Among Dutch CrossFit Athletes. Orth J Sp Med. DOI:

Poston WSC, Haddock CK et al (2016). Is High Intensity Training(HIFT)/ CrossFit Safe For Military Fitness Training. Mil Med. 181(7): 627-637. DOI: 10.7205/MILMED-D-15-00273.

Monday, February 11, 2019

Carbon Fiber Bikes Failure

See the fork break
If you're a cyclist, you would have probably seen the pictures of yesterday's crash from the failure of a carbon fiber fork. The fork snapped when the rider attempted to sprint. His teammate crashed as a result and broke his collar bone. Thankfully only one rider hurt.

Another look 
It looked like the epoxy bonding came off on one side of the fork and then the other side of the fork snapped. The cyclist is from the Integrated Riding Club and they were using Boardman bike frames previously. They just changed sponsors to this current 2019 Genesis frame.

Almost everyone who likes high performance bicycles uses a carbon fiber bike now. It's considered the norm and a wonder material since it's strong and extremely light to boot. Downside is damage to bikes with carbon fiber frames and/ or components can be hard to spot and potentially catastrophic as seen in the crash yesterday.

Of course these kinds of accidents are rare though they do happen. There was an article from Outside magazine last year highlighting other examples of carbon fiber bikes failing seemingly out of nowhere.

I spoke to Kenneth Tan from Cycleworx yesterday and he said that carbon fiber technology is "very advanced" now and not so prone to failure. In most cases, it's probably a legitimate design or manufacturing defect in the carbon fiber that leads to failure under normal conditions. Problem is it's difficult to see cracks with the naked eye before the cracks get worse and fail big time often without warning.

Kenneth says shoddy manufacturing and especially counterfeits, bikes that look like a "real" Pinarello (that Cycleworx is the agent) are the real problems. Counterfeit bikes pose a much greater risk than factory defects from a reputable brand. For those of you who don't know, Pinarello bikes are the Crème de la crème of bicycles. I've been going to Cycleworx since they opened in 1996 at the first Cycleworx location at Serangoon Gardens. And I used to ride a Fondriest and Pinarello before.

If you crashed your bike or plan to get a used carbon fiber one, get it checked by an expert. A foolproof test is to get an ultrasound scan done, but's it's pricey and not easily available here anyway. A simple test may be using a coin to tap the carbon fiber. When there's a defect in the carbon fiber it sounds a little flat compared to a "solid" sound.

Don't get me wrong, I'm not saying you need to abandon carbon fiber bikes. You just need to be aware that carbon fiber bikes need regular inspections and maintenance. Read the owner's manual and don't overtighten carbon fiber components (I'm sometimes guilty of that as I'm fearful of parts loosening and maybe causing a fall).

Me? I'm a fan of steel bikes although I do use a carbon fiber fork and seat post. Make sure you stay safe on the roads.
Steel is real for me
*From the Outside Magazine article.

"There's already a cottage industry of people who specialise in lawsuits resulting from bike accidents, including a growing cadre of attorneys and forensic experts who specialise in carbon fibre. Now that use of the material, once reserved for high-end bikes, has become widespread in the bike industry, reports of accidents and mysterious failures are on the rise. Kowal's case signals that bike manufacturers - even overseas brands - may be accountable. The result could be a dramatic spike in the number of lawsuits brought against makers of carbon fibre bike parts".  

Saturday, February 9, 2019

Trade Offs In Triathlon Training

The fastest triathlon bike?
I did my first triathlon when I was 16 years young. Coming from a cross country/ track and field background, my strongest leg was naturally the run.  Though I finished somewhere in the middle of that race (there was only the open category then), I ended up with a run time that was among the top ten fastest.

My swim and bike time was closer to the bottom half naturally. Yes, I learnt to swim when I was seven and definitely rode a bike from time to time, but my  swim/ bike timings in that race was not fast as I didn't have the specific training that I put in as a runner. Slow transitions and fumbling with my cycling cleats didn't help either.

It isn't surprising then that a particularly good performance in my run section will come at the cost of sub-par performances in the other two disciplines.

That's what I tried to explain to one of my triathlete patients (who swam competitively in school) who had an unusually fast swim but slower than normal bike and/or run splits in a recent race. Of course it may also be a simple question of pacing.

Other reasons may be genetic. His broad shoulders may work against him on the bike especially in the aerodynamics area and run for carrying the extra muscles in the upper body.

Unless you are a professional athlete, there will be a finite amount of time and energy to train. If you spend too much time on one discipline, it will be at the expense of the other two.

Sometimes, we don't observe the trade offs due to the "big houses, big cars" effect (Van Noordwijk and de Jong, 1986). Just because someone who spends a lot of money on a fancy car does not mean he/ she will not have enough money left to buy a fancy house and vice versa. In reality, we do know people who can afford big houses and many fancy cars to boot.

This scenario is usually more obvious in slower triathletes compared to faster triathletes in Ironman distances. For the triathletes with slower finishing times, faster than average bikers are very likely to have slower than average run splits and vice versa.

This is less likely as the overall finishing times get faster. In male triathletes who are capable of finishing sub nine hours, those with a faster than average bike split are also likely to have a faster than average run split. These are your athletes who can afford the "big fancy houses and big fancy cars".

The above pattern emerges when comparing different triathletes, and this may reflect differences in innate talent and/ or training levels.

However, while comparing multiple races from a single triathlete, results suggest that pacing strategies are more important. What researchers found in slower triathletes was recording a faster than usual bike time was associated with a slower than faster run time and vice versa.

The faster triathletes were not subject to this pattern. A good time on the bike did not necessarily mean a good or bad run time.

Exceptions are when you have a very good bicycle (a form of resource allocation) which can provide aerodynamic and mechanical advantages that don't have a trade off elsewhere (except your wallet).

Here's the simple truth, for mere mortals with normal jobs, with children especially, it's pretty much impossible to reach the starting line of an Ironman with sufficient / optimal preparation for all three disciplines.


Calsbeek R and Careau V (2019). Survival Of The Fittest: The Multivariate Optimization Of Performance Phenotypes. Med Sci Sports Ex. 51(2): 330-337. DOI: 10.1249/ MSS. 0000000000001788.

Van Noordwijk AJ and de Jong G (1986). Acquisition And Allocation Of Resourses: Their Influence On Variathlon In Life History Tactics. The Am Naturalist. 128(1): 137-142.

Me (left) at the 2005 SEA Games triathlon event
When I was racing, during my peak training periods, I swam up to 20 km, rode 400 km and ran 70 km a week. All this for Olympic distance racing.

I'll wake up at 4.20 am, eat a little before leaving at 4.40 am. I'll ride to the pool where we plunge in at 5.30 am sharp. This was when I swam with Joseph Schooling, Quah Ting Wen etc under Centre of Excellence (COE) coach John Dempsey. We usually end at around 7 am after which I'll ride my bike to work at the old National Stadium. (Sometimes I have to treat some of my fellow swimmers before going to work).

If I'm up to it I would do a short run before showering and seeing my first patient at 8.30 am. This was when I was working full time as a physiotherapist at the Singapore Sports Council (Sport Singapore now).

No children then and a very understanding wife definitely helps. And we definitely didn't have a big house or a fancy car then and even now. We only bought a three year old car after my first boy turned one.
Here's a closer look at my bike then