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.

Majority Of Patients Prescribed Rocker Boots Do Not Need Them

Picture from Orthomed.ca

My patient came in to our clinic with a rocker boot recently. My opinion was that she should never have been prescribed one. She just had a very mild ankle sprain. Actually, the majority of patients that I have seen coming in to our clinics in a rocker boot do not actually need them. When patients are immobilized, there are side effects from wearing the boot. 

Have a look at how quickly another patient's leg had lost its size and, of course, strength after wearing a rocker boot pictured below.

See the size difference?

Rocker boots are often over prescribed. And patients who do not know better use them for way too long. I have a cupboard in our clinic with a collection of expensive boots, donated by patients so we can loan them to patients who actually need them.

These rocker boots are also known as controlled ankle motion (CAM) boots in published studies. They are below knee devices prescribed for managing foot and ankle injuries when there is a need to reduce ankle range of motion (ROM) and to take load off the foot and ankle while allowing ambulation during recovery. 

What's good with the CAM boots are that they can be prescribed as an alternative to plaster cast bacause they cabn be removed to allowed the fracture/ wound site to be cleaned and regularly checked. When used correctly, CAM boots improved mobility, decreased hospital stays and allows for earlier return to work.

There is still a lack of clarity within the current literature over biomechanics and the effectiveness of CAM boots.

A systematic review (Stolycia et al, 2024) published last year found that compensatory mechanisms occur at the hip and knee joint during CAM usage. This is a result of the incurred leg length discrepancy (LLD) caused by the thickness of the CAM boot sole when used with standard footwear on the non injured side.

This has been found to cause secondary site pain specifically at the ipsilateral (same side of ankle injury) knee and contralateral (opposite) hip and lower back with 1 out of 3 patients reporting new or worsened pain 3 months post CAM boot wear.

There was actually a study (Harvey et al, 2010) that suggested that the incurred LLD can also cause development of knee and hip osteoarthritis later in life. This may be true for older patients who may have an early onset or worsening of osteoarthritis at the knee and hip due to overuse caused by the increased load.

Of course there are occasions where they are needed. The findings of this systematic review (Stolycia et al, 2024) show that CAM boots are useful when needed to decrease pressure from the forefoot. but not the hindfoot. This can be useful for diabetic patients for treating plantar ulcerations or in patients with a toe fracture(s) in the forefoot.

The review (Stolycia et al, 2024) also found that tall (compared to short) CAM boots (pictured above) are more effective at restricting ankle ROM. So unless you have a fracture there, wearing the boot will severly reduce your ankle ROM. For those who do, as as soon as the fracture heals, you need to stop wearing it.

So, if you have been prescribed to wear a rocker boot, please understand the rationale for it, the plan, and the timeline that you need to be in it. For many patients, they stay in their rocker boot way too long for their condition. 

To sum up, question your healthcare professional if you are asked to use one. Very often they are not necessary.

Reference

Stolycia ML, Lunn DE, Stanier W et al (2024). Biomechanical Effectiveness Of Controlled Ankle Motion Boots: A Systematic Review And Narative Synthesis. J Foot Ankle Res. 17(3): e12044. DOI: 10.1002/jfa2.12044

Can Neurodynamic Mobilization help DOMs?

Picture from The Sensitive Nervous System

We invited our neighbours over for dinner on Friday night. She had just done circuit training at Virgin Fitness a few days ago (for the 1st time in a few years) and was sore and aching all over. She definitely had delayed onset of muscle soreness (DOMs).

There's not much we can do to recover quickly from DOMs. So I was very surprised to read that neurodynamic mobilization (NM) helped with DOMs.

NM (or neural mobilization) is a physiotherapy technique (made popular by David Butler, who first wrote about this in 1991) that can treat nerve dysfunction by mobilizing the nerves. Manual techniques involve stretching, moving and even 'pulling' on nerves to improve/ restore balance between neural tissue (nerves) and surrounding structures. It helps the nerves glide (or slide) better, decreases adhesions around nerves and surrounding structures to enhance nerve function.

Our brain and the spinal cord are packed in fluid in the skull and the spinal canal. Similarly, our nerves are covered with fluid too, in a sheath like structure. It's sort of like a fluid-fluid tube (nerve) inside another fluid filled tube. 

Neurodynamic mobilization helping DOMs? Now that is news to me.

Researchers had 34 untrained males randomized into the neurodynamic mobilization (NM) or random group. Femoral nerve NM and a placebo technique were performed for 3 weeks in both groups. 

Each session consisted of 3 sets of 10 repetitions with a 2 minute break between sets. Nine sessions were conducted within 3 weeks. The participants were lying sideways on their non-dominant leg side. The physiotherapist stood behind, supporting their upper leg to have the hip in a neutral (no adduction or abduction) position. The upper dominant leg was flexed and the hip extended until soreness/ pain was felt by the patient. This was held for 3 seconds before being released. See picture A below.

Picture from article Sozlu et al, 2025

For the placebo group. the participants were also lying sideways on their non-dominant leg side. The physiotherapist was behind with the upper leg held in full extension and the hip abducted for 3 seconds while the pelvis was stabilized. Each session also consisted of 3 sets of 10 repetitions with a 2 minute break between sets. Nine sessions were also conducted within 3 weeks. See picture B above.

Subsequently, all participants did 300 maximal isokinetic contractions of their dominant leg knee extensors (thigh muscles). 

Creatine kinase, lactate dehydrogenase (both markers of muscle damage), inflammation (IL-6, TNF-α), muscle soreness, pressure pain threshold (PPT) were compared. These were measured at baseline, immediately before exercise (pre) and after (0 hours) the exercise induced muscle damage (EIMD) protocol. Measurements were also taken at 24, 48 and 72 hours after exercise.

Muscle soreness peaked at 24 hours after EIMD, while PPT was at its lowest. The NM group had significantly lower muscle soreness and higher PPT values compared to the placebo group at 0, 24, 48 and 72 hours. Muscle function scores was at its lowest at 0 hours, withe the NM group demonstrating significantly higher function scores than the placebo group both before EIMD protocol and at 0 hours. 

The researchers concluded that 3 weeks of femoral nerve NM applied to healthy untrained individuals had positive effects on DOMs. NM may help sooth inflammation and muscle damage symptoms and shorten recovery time following DOMs.

Now that will be music to my neighbour's ears!

Reference

Sozlu U, Basar S, Semsi R et al (2025). Preventative Effect Of The Neurodynamic Mobilization Technique On Delayed Onset Of Muscle Soreness: A Randomized, Single-Blinded, Placebo-Controlled Study. BMC Muscskel Diso. 26: 464. 

Is The Adductor Magnus Muscle Really An Adductor?

Picture from Getbodysmart

Our adductor magnus muscle is a very large muscle in the medial (inner) part of the thigh. It has long been thought to be a hip adductor. If you are standing with your feet wide apart and you bring your left leg in towards the midline, you will be adducting your left leg. 

Think about that movement, we do not always actively adduct a lot do we? Even while walking or running, we do not need to adduct much. Why is the adductor magnus muscle so big if we do not adduct a lot? Unless you ride horses, donkeys or ponys, what do we need such large hip adductors for?

Adductor magnus also helps with flexion and medial rotation of the hip. And if were to read about group of Japanses researchers work, it is actually a very strong hip extensor. 

A group of Japanese researchers (Takahashi et al, 2025) tested the hypothesis that the adductor magnus is actually a hip extensor more than a hip adductor.

Picture from Takahashi et al, 2025

The researchers utilized advanced diffusion tensor imaging and reconstructed the entire muscle in 15 young adults pictured above. Adductor magnus is divided into 3 portions based on fascicle insertion. The posterior (back) and anterior-distal portions comprised over 80 percent of the whole muscle volume and cross-sectional area. These 2 portions demonstrated that hip extension was more commonly being activated rather than hip adduction.

Because of this, the maximal force generating capacity of the whole muscle was over 2 fold greater for hip extension than adduction. These results support the authors' hypothesis that adductor magnus is actually a major hip extensor rather than hip adductor, challenging the traditional view of this muscle as a hip adductor.

Those of you who have read this far (thank you) must be wondering what is the big deal? Or how does this help? Consider the following pictures that show a more 3D view of the adductor magnus.

Picture by John Hull Grundy

Look at the right leg in the picture on the left. The top part is actually adductor longus. See the twist below rarely seen in 2 dimensional anatomy books? This twist allows adductor magnus to be a major stabilizer of the pelvis (hip). If you bend down to pick something off the ground, the large muscles on the front, side and back of your pelvis are doing most of the work while adductor magnus prevents them working together to throw you off balance. It is uniquely positioned to resist too much hip flexion, extension, lateral rotation of the hip, swaying side to side and hip abduction. 

Many therapists may not know that adductor magnus' squarish shape and twisted nature makes it a very important pelvic stabilizer. One that we cannot ignore when patients come in with hip or back pain.

Yes back pain included. The longest part of adductor magnus is at the back (pictured above from Anatomy Trains). It almost looks like a separate muscle with its fibers going straight down from the ischial tuberosity (just like the hamstrings) and finishing at the medial epicondyle of the femur (inner part of the knee).

 

This part of adductor magnus keeps the pelvis and your upper body from falling forward. This is done much more efficiently by this part of adductor magnus compared to the hamstrings. So when patients or other therapists tell you that you have "tight" or "short" hamstrings, it is because your hamstrings are working too hard to stabilize your pelvis and upper body from falling forward.

The next time you have low back pain or hamstring pain, consider getting your adductor magnus checked!

Reference

Takahashi K, Tozawa H, Kawama R et al 92025). Redefining Muscular Action: Human "Adductor" Magnus Is Designed To Act Primarily For Hip "Extension" Rather Than Adduction In Young Living Individuals. J App Physiol. DOI: 10.1152/japplphysiol.00600.2024

Can Faith Kipyegon Run A Sub 4 Minute Mile?

Picture from Nike

Remember Nike's Breaking 2 project where Eliud Kipchoge went under 2 hours for the marathon? Nike is at it again, this time with Kenya's Faith Kipyegon, who will attempt to make history by becoming the first woman to go under 4 minutes for the mile.

Kipyegon already holds the mile and 1500 m world records and has worn 3 Olympic gold medals in the 1500 m. Her current world record for the mile is 4:07.61 min. Can she take more than 7 seconds off the world record? It is definitely an audacious attempt, but she wants to push boundaries and "dream outside the box".

The Breaking 4 project was announced by Nike in partnership with Kipyegon last week with Nike pledging to create a "holistic system of support that optimizes every aspect of her attempt".

This is good news as Nike had fallen behind their competitors during the Covid-19 years. Then Nike CEO John Donahoe who was appointed in January 2020 for his digital chops so he could help Nike cut out retailers (like Foot Locker and Macy's) by improving their e-commerce operations. As Nike cut off their wholesale partners, it paved the way for other upstart competitors like On Running and Hoka to take over crucial shelf space and grab market share.

Personally, I felt that Donahoe (former eBay and ServiceNow CEO), lacked the deep understanding required for the sneaker culture and industry that Nike required. Donahoe went too much into releasing different editions of Nike's classic sneaker lines (Dunks, Air Force 1's and Air Jordans). He  neglected the innovation section which led to Nike developing the Alphafly's that help Kipchoge break 2 hours  for the marathon.

Am glad he was replaced by Elliot Hill as CEO in October, 2024. Hill had retired from Nike in 2020, prior to Donahue being appointed. Hill was previously with Nike for more than 32 years. He will be better at getting back to the fundamentals that made Nike the market leader in sneakers and athletic apparel previously.

Kipyegon currently trains in Kenya with Kipchoge (who else) while Nike has a team at its headquarters in Oregon crafting her spikes and apparel while analyzing her scans to help her. 

She will only make 1 attempt on June 26, 2025 at the Stade Charlety in Paris, where she previously set world records for the 5,000 metres in 2023 and the 1,500 metres in 2024.

Can she break the world record? Da Silva and colleagues (2025) recently published an article suggesting that with "greatly improved" yet "reasonable" aerodynamic drafting off pacesetters, Kipygeon can break the barrier. 

Let's see if she can do it.

Reference

Da Silva ES, Hoogkamer W, Kipp S et al (2025). Could A Female Athlete Run A 4-Minute Mile With Improved Aerodynamic Drafting? Royal Soc Open Sci. DOI: 10.1098/rsos.241564