3 Common Sites Of Musculotendinous Junction Injuries

I recently had a patient with a musculotendinous junction injury. Also known as the muscle-tendon junction (MTJ), it acts like a bridge to transfer forces from the muscle via the tendon to the connecting bone the muscle attaches to. This allows for movement to take place. 

It is a special area where the muscle's fascia connects and inersects with tendon tissue. Structurally, the MTJ is seamlessly integrated into the tendon, with finger-like folds increasing the surface area for a stronger connection and to distribute stress (pictured above).

It's a common site for injury as the MTJ undergoes some stress during daily activities and substanstial stress while playing sports. MTJ injury is often accompanied with both muscle and tendon injuries leading to restricted force trasmission.

Due to it's highly specialized structure, it does not often heal well after injury. Conservative treatment are mostly effective for minor MTJ sprains while partial tears and complete ruptures will require surgical intervention.

It can happen during a fall leading to trauma to the area. It often occurs due to repeated overload, usually from high intensity training in young athletes or overuse in middle age or older adults. My observations are MTJ injuries usually happen after a period of rest/ decreased muscle use followed by a period of intense muscle activity. 

An example who be my patient mentioned above. He went on holiday for 3 weeks with no exercise and resumed his weekly basketball game on returrn and promptly tore his hamstrings at the MTJ. These tears occur frequently during eccentric muscle loading. 

They are usually complete muscle tears. In hamstring injuries this account for 14.4% of all bicep femoris injuries. The supraspinatus muscle has the highest incidence of the tendon midsubstance injuries (11.4%). Complete tendon avulsions are more frequent in the triceps brachii and pectoralis major.

Conservative treatmant options like rest, ice and compression etc helps in the initial stages if the tear is small. Several studies have indicated that surgical treatment yields better results in terms of function, strength, patient ratings and recovery to pre-injury performance for the more serious tears.

Continous development of tissue engineering that focuses on regenerating new tissue from cells are now helpful to MTJ injuries by utilizing biological and synthetic scaffold-based tissue. This helps in the repair and healing of MTJ tears. However it is not easy to fully mimic the unique characteristics of our muscles, tendons and the MTJ itself.

Hopefully, newer polymers and scaffolds will help with healing of MTJ injuries in the future. For now, please be vigilant in your exercise after a period of rest. Avoid exercising at higher intensities initially while allowing for your muscles to adapt again. Note that the calf, pectoralis major (chest) and hamstrings are the most vulnearble areas.

Reference

Tong Sm Sun Y, Kuang B et al (2024). A Comprehensive Review Of Muscle-Tendon Junction: Structure, Function, Injury And Repair. Biomedicines 12, 243. DOI: 10.3390/biomedicines12020423

The Old Do Not Need Gentle Movement

Picture from NRI Nation

I was very surprised to read that older adults need more than gentle movement. They need strength. Yes, a lot of stength if you read the following review by Toien et al (2025). This is in contrast to current guidelines which recommend low to moderate intensity (60-70 percent of 1 RM) and slow to moderate concentric velocity.

The review showed convincing benefits of maximal strength training (MST) in healthy and 'diseased' older adults including frail and post stroke patients. Training performed with heavy (80-84 percent) of 1 RM and very heavy loads (>85% of 1 RM).

Key benefits were increased strength gains (2.5 percent per session). 4.5 percent increases in muscle power per session. Increase in Type II muscle fiber size, decrease in oxygen cost of walking and stair climbing. It also helps with balance.

MST uses loads of about 90% of 1 RM, which can only be performed a maximum of 3-5 reps, 3-5 sets and maximum intentional concentric velocity.

Here are the guidelines. Do 4 sets of 4 reps at about 90% of 1 RM or 4 RM. Do this 2 to 3 times a week. Single set options are also effective twice  a week. Prioritize lower body compound lifts e.g. leg press, squats, step ups since strength reduction is more effective in lower compared to upper limbs with increasing age. Moreover the lower limbs are crucial for walking during everyday activities. 

Picture from article

For this, a horizontal leg press (pictured above) may be ideal over a free weight squat since technique and safety will minimally limit the intensity of the load. The health care provider needs to consider the main challenges of the specific disease or individual. Those with osteopenia or osteoporosis will benefit from axial loading through the spine to stimulate bone density enhancement. The hack squat or horizontal leg press where the back can be reclined to ensure loading through the spine is recommended to attain this axial loading of the spine while also protecting the impact of the heavy load. 

Some diseases or injuries may require other exercises to target an affected or impaired muscle or muscle group. Examples may include the bench press for wheelchair users, dorsiflexion for foot drop patients or hip abduction following hip surgery. Also note that very heavy unilateral (or single leg) strength training induces adaptations in the untrained, opposite injured limb. This is useful during acute or chronic periods of immobilization to limit the loss of function in the immobilized limb.

Supervised training are encouraged since it improves safety and confidence.

It is a very interesting read since it is good to have evidence that it is safe to use the heavier strength training lifts compared to the current guidelines. I am wondering if the 4 sets of 4 repetitions at 90 percent of 1 RM for older patients is a recipe for injury. Is the volume and frequency of the MST sustainable for the long term?

Reference

Toein T, Berg OK, Modena R et al (2025). Heavy Strength Training In Older Adults: Implications For Health, Disease And Physical Performance. J Cachexia Sar Muscle. 16(2): e13804. DOI: 10.002/jcsm.13804

Day 2 Of Kinesio Foundations Course

Ligament correction with Dr Frank Liew (dentist)

Most of the participants already took the Kinesio tapes off after the the first day. For the few who still haves them on, we started with some questions on how tape left overnight felt. The participants discussed why there were good or adverse reactions.

What's up Dr Kong (on the right)?

Day 2 Of Kinesio Foundations Course started with corrective techniques. Mechanical correction, fascia correction, ligament/ tendon correction and spring assist etc

Surprisingly, the 2nd day of the course zipped by much quicker than usual as we went through more the corrective techniques. There were practical applications such the association of MCL (medial collateral ligament) and your pes anserinus, how a rotated pelvis would affect the shoulder. How the hip affects the knee and also strategies on how to treat a foot drop. We covered all that and more.

Cutting the tape for EDF, jelly fish - not easy

The coup de grace were the EDF and jelly fish taping affecting the epidermis, dermis and fascia. The participants realized it's much easier to have a good pair of scissors for the EDF techniques.

A big thank you to the participants, my family and colleagues for helping out. Would not have done it without all of you. Looking forward to the next course.

Day 1 Of Kinesio Foundations Course

Sports Solutions hosted Day 1 of the Kinesio Foundations Course today. It's been quite a few years since we have had this course. During that course, we had 2 participants from Saudi Arabia. 

This time it's all local with 15 participants. We have 4 medical doctors, 1 dentist, 1 occupational therapist with physiotherapists rounding out the rest.

The course is now a two day in person course with a 4 hour online pre course. Compared to the 2 previous versions of the course, there is now a much bigger emphasis on the Kinesio Medical Taping section instead of just the Kinesio Taping Methods where muscles, joint and tendons were the main focus. 

Here are some of the pictures from today.

Stay tuned for Day 2 tomorrow.

Zone 2 or HIIT? Or Neither?

My 58 year old patient walked in yesterday to the treatment room and the first question she asked was if she should start HIIT training. Woah! Hang on, I said to her do you really know what HIIT is? (*See end of article for what HIIT is please).

She said her friends, children and all the fitness influencers she sees extols the benefits of HIIT. Then without batting an eyelid, she said, "What about Zone 2 training?"

That is basically what is happening online. One group says train at Zone 2 while the other says go hard or go home, HIIT is the way to go.  

What do the best in the world actually do? A new study by Sandbakk et al (published in April 2025) investigated elite endurance coaches and their training were not what you expected. These coaches had athletes winning more than 380 international medals in long distance running, biathlon, rowing, cross country skiing, road cycling, swimming, triathlon and speed skating.

All the coaches stick to a traditional periodization model, including a gradual shift towards overall lower training volume and more competition-specific (race pace) training as the competitive period approaches.

Another common emerging feature was an emphasis on high volume low intensity training. Look at the picture above, MOST (80-90 percent) of the weekly training was easy. Here is the key insight, majority of the easy work was not in Zone 2. It was in Zone 1. Slower than what the internet experts are obsessed with. Slower means more sustainable and more adaptation over time. That's how you get stronger. 

True aerobic development is only possible from accumulating volume. It also allows one to recover and handle key sessions. 

This Zone 1 low intensity sessions along with combined with 2-3 weekly "key workout" days consisting of 3-5 intensive training sessions. The sessions are purposeful and focused, with recovery all planned. 

Finally, coaches across all sports focused on getting high training quality by optimizing training sessions by controlling the load-recovery balance to ensure optimal preparations for major competitions.

The athletes go through all the zones (see the above picture), not just high intensity (Zone 5), but also in between. Short, fast intervals and controlled thresholds. The exact proportion is dependent on their competition demands. There were not a lot of really hard anaerobic sessions. 

Why the big difference between these elite coaches and what we see online with all the fitness influencers? Firstly the fitness influencers usually do not compete in races or competitions. They won't be posting so many videos if they do. Train easy, adapt, get stronger does not sell as well as "unlocking this magic Zone of HIIT". High performance is not about shortcuts. It's about accumulating consistency over time. Not as attention catching, but it definitely works.

To sum up, it's mostly sessions of low intensity, with occasionally high sessions adjusted to the individual. Balance stress and recovery and consistency over all else. Now you know.

* Many gyms, fitness influencers and trainers get patients to do what is traditionally circuit training but call it HIIT. Circuit training is like 30 seconds doing push ups, rest a minute, go to another station and perform 30 seconds of high knee lifts, rest a min, 30 seconds of lifting dumbbells etc

HIIT stands for high intensity interval training. Or interval training for short.  Example, 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). You can also cycle intervals outdoors or on a trainer with your bicycle attached.

Circuit training does not sound sexy, but HIIT certainly does!

Reference

Sandbakk O, Tonnessen E, Sandbakk SB et al (2025). Best-practice Training Characteristics Within Olympic Endurance SpoRts As Described By Norwegian World-Class Coaches. Sports Med 11:45. DOI: 10.1186/s40978-025000848-3

Are Treadmill Calorie Counters Accurate?

My patient said he ran 20 km on a treadmill recently. He also told me stats like his average pace and treadmill incline of the run and calories burned. Since he mentioned about the calories he burned, I told him that they were not very accurate.

Different treadmill manufacturers will have their own formulas that they use for their treadmills, elliptical, X-trainer, stepper etc. Speed, treadmill incline, and distance are typically used to calculate how many calories you burned.

However, for a more accurate reading, your gender, height, weight, muscle, fat mass, heart rate and fitness levels are typically needed as well. Note that a higher heart rate may be associated with greater energy expenditure, hence a lower heart rate running at a certain pace means you are fitter and will burn less calories.

Heart rate is affected by temperature (of the gym), medication, food you ate, what muscles are being used and whether your run is continuous or in spurts/ bursts.

You may also notice that your run becomes much easier when you hold onto the hand rails while running. By taking some weight off by holding on to the rails, actual effort is reduced but the calorie counter does not account for that and will overestimate calories expended.

Treadmills and elliptical machines need to be calibrated regularly (especially in busy commercial gyms) otherwise the speed you may be running at may not be accurate. That discrepancy alone can influence the accuracy of the calorie count.

I could not find much research specifically on how accurate the calorie counts on treadmills. There was a 2018 study by Glave et al (referenced below) involving elliptical machines. Their study found that the calories burned were significantly overestimated. More than 100 calories were added for a 30 minute workout.

So take your exercise machine calorie counts with many grains of salt since they are definitely not accurate and may be way off in some cases.

You can certainly use a smart watch to track your calorie estimates too but even these tend to overestimate energy expenditure. My previous post covered that, but do note that fitness and smart watch technology is consistently improving so they may be more accurate now.

One can also use an online calorie counter to provide an estimate of how many calories you've used. Again it's just an estimate.

Remember not to totally rely on treadmill calorie counts or your smart watch to rule your workout. Sticking to your exercise plan consistently is what really counts, not just the numbers you see on the treadmill or elliptical machine.

Reference

Glave P, Didier JJ, Oden GL et al (2018). Caloric Expenditure Estimation Differences Between An Elliptical Machine And Indirect Calorimetry. Ex Med. 2:8. DOI: 10.26644/em.2018.008

Past Versus Present

Adizero PR (top) versus Adizero X Parley

I've always preferrred running in racing flats so I ordered the OG Adizero PR a few weeks ago when I saw them online. I'd worn quite a few pairs of those in the early 2000's when they were really popular. Actually, Adidas made a custom pair for me when I represented Singapore at the SEA Games triathlon event in 2005 (pictured below).

I did my first run in them on Friday 2 days ago. It was a terrible run! Compared to my previous Adidas racing flats, the Adizero X Parley (which I bought in 2023), I felt the hard ground with every single step.

Adizero PR

My calfs were sore and tired after less than a kilometer of running. Later, I went back to the Adidas website and realized that the Adizero PR's foam was EVA foam compared to the Parley's more advanced Lightstrike foam (pictured below).

Adizero X Parley

Meanwhile, have a look at the humble, really minimalist 1970 Onitsuka Tiger (now known as Asics) compared to the 2025 Asics carbon plated supershoe pictured below. One used for marathons back in the 1970's and the one used currently. The latest version is packed with space age technology. 

Those who raced marathons back in the 1970's used shoes with almost no cushioning, no support and definitely no energy return. The classic Onitsuka Tiger model has an almost zero drop profile and super thin outsole (to save weight). Runners back then needed super efficient running form/ technique, lots of grit and mental toughness since there was no technology back then. There will not be many runners who heel strike with these shoes. They will feel it straight away. Heel strikers back then were definitely 'handicapped'.

And guess what, these shoes are now still making the rounds as a casual sneaker and making Onitsuka Tiger / Asics lots of money.

Now in 2025, we have super highly stacked midsoles, super responsive PEBA foam, uppers that are  optimized biomechanically and carbon plates of course. These can offer runners with energy return on every stride, propulsion and fit designed to minimize fatigue over the whole marathon distance. Just like wearing a springboard when you run.

Today's footwear gives an undeniable edge to help you train and race and definitely run faster. Especially for weaker runners who cannot rely on their muscles as much and efficient running form to run injury free. Good to be able to run and not feel 'damaged' post run. 

I still prefer to be lower to the ground and more stable compared to feeling more 'wobbly' when the midsole is stacked higher. Definitely does not help when you have to turn around on a run or avoid a child on the pavement. I've treated many runners who have sprained their ankles as a result.

I probably will not run in super shoes yet. Call me old school (or OG- original gangster), but I still prefer to be lower to the ground. I prefer the newer versions of the racing flats using PEBA instead of EVA foam. But no highly stacked midsoles and no carbon plates. Not yet anyway.