Sunday, April 18, 2021

Does Your Growing Child Have Knee Pain?

Recently, we have seen some young athletes in our clinics, complaining about pain after playing sport. I've written about growing pain  in young children/ athletes before. When these children/ athletes are having a growth spurt during adolescence, the long bones grow faster than muscles. The muscles take a while to lengthen so the muscles tend to pull on the attachments on the bone.

This is especially so when a child is active, the muscles will pull on the bony attachments where the muscles attach causing pain (also known as apophysitis).

An area of pain at the knee which is common in children is known as Osgood Schlatters disease (OSD). The pain is located where the patella tendon finishes at the tibia, known as the tibial tuberosity.

Researchers from Denmark studied 51 youth athletes (51 percent female) between the ages to 10 to 14 with OSD. The youths already had pain for an average of 21 months.  Intervention consisted of four visits with a physiotherapist with both child and parent. The first block of treatment focused on decreasing load through decreased activity, education and static hold exercises.

The next block the subjects progressed to exercises which led to a return to their sport. Follow up was done at 4,8,12, 26 and 52 weeks. 

All subjects showed improvement at 12 weeks (study endpoint) with less kids complaining of pain and increased function and quality of life. 31 percent of subjects still suffered from discomfort at 12 weeks, discomfort that they would be not happy to live with, while 80 percent were very satisfied with their treatment results.

Only 16 percent of the subjects managed to return to their sport (RTS) at 12 weeks, compared to 69 percent at 52 weeks follow up. Thigh and hip abduction strength which was the focus of the exercise interventions improved significantly by 12 weeks as did vertical and horizontal single leg jumps.

At one year follow up, only 5 percent of subjects were very unsatisfied with their progress and unable to return to sport.

The study called for significant restrictions (guided by pain/ symptoms response) at the start of sporting activity to decrease load on the tibial tuberosity. Data from the tracking device the subjects wore prior to start of the study to the first block of treatment showed a decrease of 15 minutes per day of moderate to vigorous activity. This may suggest that getting active kids to slow down is difficult. 

Parents may need to explain to the child that activity modification is key to reducing symptoms. Reining in the kids in the short term will help return to sport sooner.

Surprisingly, the tracking devices showed that activity levels decreased by 37 minutes per day by week 12, suggesting that although many reported feeling better and can do more, they were actually less active.

We usually do not encourage stretching the affected muscle as static stretching can place more traction forces on the tendon insertion on the bone. Correct strength training that is pain free often helps to take the load off the tendon attachment. Meaning the weight does not have to be heavy. Elastic bands are very useful too when the young patients cannot handle the weight.

Please come and see us in our clinics if your young and teenage athletes need help.


Rathleff MS, Winiarski L, Krommes K et al 92020). Activity Modification And Knee Strengthening For Osgood-Schlatter Disease: A Prospective Cohort Study. Ortho J Sp Med.6(4): 2325967120911106. DOI: 10.1177/2325967120911106

*note that OSD or Osgood Schlatter's disease is not a disease. It is named after Robert Osgood (1873-1956) and Carl Schlatter (1864-1934), an American and Swiss surgeon respectively that described the condition concurrently.

Wednesday, April 14, 2021

Where The Streets Have Allyson Felix

I've written about Allyson Felix before previously and I hope she will still be a force to reckon with at the Tokyo Olympics. Being Nike's poster girl previously, I admired how she spoke up when Nike were unfair to their sponsored pregnant athletes.

As you can see from the article above, she still found a way to train when stadiums were closed during the lockdown after getting her coach to use a measuring wheel to mark out distances "on literally the street in front of her door". 

What a sight it must have been for her neighbors to behold when a six-time Olympic Olympic gold medalist, 13 times World Champion comes sprinting down the road at full speed. Along with her coach yelling encouragement at the top of his voice. 

Instead of complaining about what she can't do, I love the way she and other athletes resorted to unorthodox ways to train so they can be ready to compete when they can. 

I know too, that our Team Singapore athletes have resorted to ingenious ways to train too, chapeau to them. 

Let's see how she fares if the Olympics does go on.

Sunday, April 11, 2021

Can Your Menstrual Cycle Make You More Prone To Injury?

Photo by Jeffrey F Lin from Unsplash

Ladies, it's true that sometimes men don't get it, but not the way you think. Not when it comes to injury risk anyway. 

I've written way back in 2009 that women are more prone to ACL injuries compared to men during the time of the month because changing hormone levels affect ligament strength. The bad news is it's not just ligaments. Researchers found evidence that muscles, tendons, joint and ligaments were more affected across the menstrual cycle.

The English women's national football team (from under-15's to the senior squad) were studied over a four-year period for this study. Injuries during training camps and competitions were tracked. Only players with regular menstrual cycles and not on hormonal contraceptives were included in the analysis. 156 injuries from 113 players were recorded.

The key finding seems to be that estrogen has broad effects on decreasing stiffness of ligaments and tendons. While this is may be helpful during childbirth, it also make your knees, ankles and other joints less stable when estrogen levels are higher.

My wife explains that at the start of menstruation (which is the follicular phase), estrogen is lowest.  Estrogen levels begin to rise to a peak shortly before ovulation (luteal phase). It then drops sharply, before rising again to a gentler peak during the luteal phase.

Bearing the above in mind, ACL injuries tends to be more likely during the late follicular phase where estrogen levels tend to be highest and ligaments tend to be loosest. During this phase, knee joints get one to five millimeters looser (Chidi-Ogbolu and Baar, 2018). 

It can be that tendons that have became looser or more lax may actually decrease injuries to the muscles since they may be able to absorb some of the impact from forces that may strain or tear a muscle (Chidi-Ogbolu and Baar, 2018). 

The analysis showed that muscle and tendon injuries were about twice as likely during the late follicular phase (higher estrogen levels leading to lax muscles and tendons) compared to other phases.

Joint and ligament injuries were significantly less during the late follicular phase (24 in total). Quite the opposite of the study's hypothesis (lax ligaments bad, lax tendons good).

An interesting note was that 20 percent of the injuries happened when a player's menstrual cycle was late or overdue (based on when the players expected their next period to start). This may be due to the "female athlete triad", which involves persistent calorie deficits and can lead to missed or irregular periods, lower bone density and increased overall injury risk.

Some of you reading this may be planning to avoid contraceptives during training and then using them during during the competition season since hormonal contraceptives can be protective of ligaments (since they suppress the higher peaks in estrogen). Beware of the trade-offs though, higher estrogen levels help promote muscle building and repair muscles and tendons in response to training.

It is clear that hormonal fluctuations matter although clearer guidelines on the menstrual cycle may be needed since knowing estrogen can affect injury risk may not pan out totally in the real world. 

My suggestion would be to track and record your periods so you are aware of what factors can and may be at training/ competition. Knowledge is certainly power in this case.

More research is definitely needed and you'll be the first to know the latest information when you read it in our blogs.


Chidi-Ogbolu N and Barr K (2019). Effect Of Estrogen On Musculoskeletal Performance And Injury Risk. Frontiers Physiol. 9: 1834. DOI: 10.3390/fphys.2018.01834.

Martin D, Timmins K, Cowie C et al (2021). Injury Incidence Across The Menstrual Cycle In International Footballers. Frontiers in Sp Active Living. DOI: 10.3389/fspo.2021.616999.

Sunday, April 4, 2021

Scoff Not At Elastic Resistance Bands

Tan Howe Liang(pictured below) is still the strongest man I know. Yes, the same Tan Howe Liang that won Singapore's first ever medal at the 1960 Rome Olympics. He was a senior gym instructor at the gym at the old National Stadium and we often bumped into each other when I was still working there. I was always amazed when he told stories about his training days. Mind you, he could still squat with very heavy weights whenever I saw him train then. 

Silver at the Rome Olympics, SNOC picture

But don't fret if you don't have easy access to a gym or other fancy, expensive gym equipment. Other than your bodyweight, elastic resistance bands can be great for strengthening muscles too.

Not many of you may believe me if I said that training with elastic bands can be just as effective as training with weights for strengthening muscles.

The following systematic review and meta-analysis is possibly the first to compare the effects of strength training for strength gains with elastic tubes and bands versus conventional devices (dumbbells and weight machines).

The search identified 365 articles, of which eight studies were within the inclusion criteria comprising of 224 individuals between 15 to 88 years old. All subjects were performing regular strength training. In these groups were physically active individuals, athletes, individuals with coronary heart disease and moderate chronic obstructive pulmonary diseases.

Results of the meta-analysis showed that there is no superiority for both upper and lower limbs between training performed with elastic bands and training with free weights on strength gains. This was consistent across groups mentioned above and also when compared with a control group in the elderly, individuals with osteoarthritis and even fibromyalgia. 

The authors conclude that training with elastic bands is just as good as conventional resistance for promoting strength gains in different populations using diverse protocols. 

Having elastic bands at home to train with eliminates the need to travel to the gym and this may be more practical and a lot cheaper for certain people who may find it difficult to go to a gym. patients will have greater adherence to strengthening programs too. 

Personally I feel elastic bands are great for strengthening and correcting muscular imbalances. I still use them on a very regular basis. Especially after my accident.

Exercising with bands in my back brace in 2013

Do not let anyone tell you that you are wasting time if you are not using heavy weights and expensive equipment. Effective strength training can be achieved with body weight, free weights and especially elastic bands too.

We have managed to rehabilitate many national athletes back from injury and even avoid surgery in many cases using elastic bands to strengthen the injured areas. Especially in cases when a weight plate/ bar is initially too heavy and risk further injury and load to the person's joints.


Lopes JSS, Machado AF, Micheletti JK et al (2019). Effects Of Training With Elastic Resistance Versus Conventional Resistance On Muscular Strength: A Systematic Review and Meta-analysis. Sage Open Med. DOI: 10.1177/2050312119831116.

Don't neglect the legs

Sunday, March 28, 2021

Overdoing HIIT Sessions Can Affect Your Health

Picture by Ving Henson from The Pit

Many of my patients tell me they are doing HIIT classes now. If you interested about your fitness and have been exercising regularly, you will definitely know what HIIT stands for. High intensity, interval training.

When I was a teenage runner, those intervals we did certainly did not have such a fancy name like HIIT. You run 15 intervals or repetitions of 400m with a one minute rest in between or the coach will say run 6 x 1km going every 5 minutes (meaning if you run your kilometer in 3:50 min, you get 1:10 min rest before starting again).

I've written how HIIT can be beneficial and how it can even reduce growth in cancer cells. Since HIIT is a super time efficient method for improving aerobic fitness and other health outcomes and metabolic conditions such as diabetes, high cholesterol or high blood pressure.

One such outcome is increasing our cell mitochondria (power generators in our cells) in our muscles. With more mitochondria in our cells, we become stronger. 

Before you think more HIIT is better, a recent small study showed that people who tried to do 5 HIIT sessions in a week ended up with sudden and severe declines in their mitochondria function, along with blood sugar dysfunction. 

When the subjects decreased their HIIT sessions, their metabolic condition started to improve but did not disappear, hinting that the benefits of extremely strenuous exercise may still depend on how much we do and how we allow ourselves to rest and recover.

The researchers first tested the subjects in their lab for the current fitness levels and metabolic health, which included blood sugar levels throughout the day. In the first week, 2 sessions of HIIT were performed, 5 reps of 4 minute long bike intervals on a stationary bike with 3 mins rest in between. The subjects pedaled as hard as they could while their power output was tracked. Their leg muscles were biopsied while a 24 hour blood sugar control was investigated.

In week 2, they did 3 HIIT sessions while increasing some of their intervals to 8 minutes. During week 3, they did 5 HIIT sessions with a mix of 4 and 8 minute intervals of all out cycling. Week 4 allowed for some recovery and they subjects and the amount and intensity of exercises were halved. All the tests were repeated weekly.

The findings showed the subjects getting stronger by week 2. They were pedaling harder and getting fitter, better daily blood sugar control and more mitochondria in the cells. These mitochondria were also more efficient, producing greater energy compared to baseline.

However, by week 3, the subjects were not able to generate more power, their muscle biopsies showed that their mitochondria were only producing 60 percent of the energy of week 2. Blood sugar control levels were spiking and dipping throughout the day.

After allowing for recovery in week 4, the following week showed the mitochondria producing more energy, but still 25 percent less than week 2. Blood sugar levels stabilized too, but again not to the same extent as week 2. The subjects could however ride with the same or even greater vigor as with week 2.

The researchers did not find out what exactly caused the decline in results (glucose intolerance and insulin secretion)  that occurred after week 3. It may be the combination of total biochemical changes that weakened the mitochondria which in turn disrupted the blood sugar control levels.

This study was done on normal healthy subjects and not athletes nor people with metabolic conditions such as diabetes, high cholesterol or high blood pressure, so the latter group attempting such training must get the go ahead from your medical professional.

For those of us who just want to be healthier, don't do HIIT sessions excessively since previous studies and formal recommendations suggest 3 intense sessions in a week as maximum. Otherwise, injuries may come knocking on your doors too. 

The researchers managed to assess blood glucose profiles in world class endurance athletes and found that they, too had impaired glucose control when compared with a matched control group. So for athletes who want to be stronger, faster quicker, do allow ample time for recovery between training sessions.


Flockhart M, Nilsson LC, Tais S et al (2021). Excessive Exercise Training Causes Mitochondrial Functional Impairment And Decreases Glucose Tolerance In Healthy Volunteers. Cell Metab. DOI: 10.1016/jcmet.2021.02.017

Sunday, March 21, 2021

Reliable Predictors Of Running Injuries

You need a new pair of running shoes so you decide to go to a specialist running store to choose a pair that's suitable for you. The store manager at the specialist running store tells you to hop onto their in store treadmill and 'analyzes' your running gait.

He then proceeds to critique your running gait and its biomechanical implications. And suggests the most expensive running shoe (in the store) for you so you do not get injured. Is that a common scenario that happens?

Contrary to several long held beliefs, most biomechanical and structural factors are not reliable factors at predicting running injuries

Researchers studied 300 runners who have been injury-free for the past six months and found several more reliable factors (rather than biomechanical and structural factors) in predicting who would be more likely to get injured.

The runners' demographics, physiology, biomechanics, psychosocial issues and training were documented. Their hamstrings, quadriceps muscle strength, knee, ankle flexibility, arch height of their feet were tested. 

A gait analysis studied how their feet, knees and hips distribute forces while running

Any runner who reported an injury were followed up at six and twelve months later. After the first year, the researchers emailed the injured runners a biweekly questionnaire asking them what injuries they sustained in the past two weeks.

Those that were injured went to a doctor and physiotherapist who were part of the study for treatment.

Results of their study after the two year follow up indicate that female runners sustain injuries at a higher rate than male runners. Stiffness in the knee joint, which were more common in runners weighing more than 80 kg significantly increases the chances of an overuse running injury. 

The runners who were injured also reported significantly worse mental health related to their quality of life and more negative emotions compared to the non injured runners.

Most biomechanical, structural factors like arch height, overpronation, flexibility, Q-angle  (see picture above), lower limb strength, weekly mileage, footwear and previous injury are not reliable factors for overuse running injuries.

The researchers recommended that caution should be used when trying to alter what were commonly thought risk factors such as excessive pronation, poor flexibility, weekly mileage etc unless a runner has extreme values.

It appears from this study that the importance of biomechanics and anatomical structures assumed by doctors, physiotherapists, personal trainers and other clinicians are not as high risk as assumed. 

I feel that this does not mean they are not important. It is still important to consider the individual patient/ runner when assessing their condition. 

We still need to be aware of each patient's individual structural and biomechanical anomalies, but not to the point where we nitpick every discrepancy in strength, joint angle, foot position and range of motion.      


Messier SP, Martin DF, Shannon L et al (2018). A 2-Year Prospective Cohort Study Of Overuse Running Injuries: The Runners Injury Longitudinal Study (TRAILS). AJSM. 46(9): 2211-2221. DOI: 10.1177/0363546518773755

Sunday, March 14, 2021

Is It Better To Bend Your Back Or Knees When Picking Something Off The Ground?

Thanks to Tasneem and Joakim for the photo

I can't find any similar statistics in the local Singapore context, but more than 40% of employees in European countries suffer from work related musculoskeletal disorders (WMSD) yearly. This results in 3-6% absence from work, affecting 2.5% of the gross domestic product across Europe. 52% of injuries are attributed to overloading during lifting tasks, of which 65% affect the lower back.

When picking up something off the floor, we generally use two standard lifting techniques, the stoop or squat technique, which have been well described in many articles. The squatting technique is usually advised when lifting heavy objects since this technique is thought to result in lowering intervertebral disc (IVD) compression and shear forces compared to the stoop technique. 

Squat (a) versus Stoop (b)

Stoop lifting is usually restricted to lifting light objects since it is thought that stoop lifting causes higher IVD compression and shear forces compared to the squat.

However, there is no agreement or sound evidence for lifting ergonomic guidelines (or good lifting techniques). Hence the following study to investigate if squat or stoop lifting imposes more load on the person lifting.

Different weights were tested for both lifting techniques using a full body musculoskeletal model, 3D marker and ground reaction forces. They were used to calculate joint angles, forces and power. Muscle activity of nine different muscles were also measured to calculate effort.

Ready for the results? For all lifting conditions and both techniques, the highest joint forces during lifting and lowering were at the L5S1 spine levels, followed by the hip and knee. The hip joint generated the most power while lifting for both techniques.

Squat lifting was mainly executed by additional work on the knee extensors (Quadriceps), shoulder and elbow, potentially explaining similar prevalence of WMSD in the shoulder, elbow to LBP in people who do frequent lifting. 

The authors concluded that based on their findings, squat lifting is not favored over stoop lifting (this is in contrast to current recommendations) although forces were slightly higher in the L5,S1, hip and knee during the stoop technique. This is also supported by Van Dieen et al (1999) who concluded that there is no evidence to suggest squat over stoop lifting after reviewing 27 studies.

Now, many of you reading this may already not agree with what the authors concluded. There are so many variables that can change the results. How low the object is will influence the load on the back, making comparisons with other studies difficult. 

Even a small adjustment like turning the knees out (not controlled in this study) while squatting already reduces back loading. Likewise, healthy volunteers in this study will likely have different lifting dynamics compared to real blue collar/ laborers since the latter would have efficient strategies for all the lifting done over the years. Lifting in the research setting may not totally replicate real world situations.

Weight (10kg in this study) and dimensions of the load lifted will definitely affect the lifting technique as well since the box (length 36 cm, width 14 cm and height 21 cm) used in this study was relatively small. 

For those of you who do not have low back pain, this post may possibly challenge or even change the way you lift a box off the ground or while picking a pen that you've dropped. You have always been told that when you're picking up something or lifting that you should bend your knees, keep your back straight before you lift. That is supposed to be good form or good ergonomics.

Well, especially for those of you who are pain free, you can say to anyone who insist you bend your knees and not your back while lifting that it is not totally true. 


Van Der Have A, Van Rossom S and Jonkers I (2019). Squat Lifting Imposes Higher Peak Joint And Muscle Loading Compared to Stoop Lifting. Ap Sci 9(18): 3794. DOI: 10.3390/app9183794

Van Dieen JH, Hoozemans MJM and Toussaint HM (1999). Stoop Or Squat: A Review Of Biomechanical Studies On Lifting Technique. Clin Biomech. 14: 686-696

Thank you for reading this long article. If you're interested, another study by Mawston et al, (2021) pictured above and referenced below found that during a maximal lift in pain free individuals, a flexed lumbar spine (picture C) is more efficient and stronger as opposed to a straight spine! So much for having a 'good' posture while weight training. Perhaps that shall be another post.

Mawston G, Holder L, O' Sullivan P et al (2021). Flexed Lumbar Spine Postures Are Associated With Greater Strength And Efficiency Than Lordotic Postures During A Maximal Lift In Pain-free Individuals. Gait and Posture. DOI: 10.1016/j.gaitpost.2021.02.029