Perhaps We Got Lactic Acid All Wrong

I think I got it wrong anyway. Remember the last time you pushed yourself way too hard while exercising? The buildup in lactic acid feels like a sharp, intense burning sensation in your working muscles. Your muscles feel really heavy, you quickly fatigue and you suddenly lose strength. This feeling goes away rather quickly when you slow down or stop.

What if we misunderstood what lactate (or lactic acid) is all this while? What if lactate does not slow you down but is actually a nutritional super fuel?

Yes, lactate has been accused to be the culprit behind behind 'burning' legs previously, but is now thought to be endurance sport's next nutritional breakthrough. 

Yomif Kejelcha used lactate gels (Spanish brand Santa Madre's Lactate 60) while finishing 2nd and also clocking sub 2 hours in the London marathon earlier this year. In fact, Tadej Pogacar has been trialing a Enervit 'lactate gel' (a gel with lactic acid) since 2024 when he won the Tour De France for the 3rd time. Pogacar recently won his 5th Tour De France this year.

Tadej Pogacar using Enervit's C2:1Pro Lactate Gel

So what are these new lactate gels and what is the science behind them? I was skeptical as I have been taught that lactate was the 'enemy', a by product that is responsible for burning legs and fatigue, not as a potential fuel source.

Going into Pogacar's jersey pocket

It all started in 2020 when Basque researcher Aitor Viribay first documented how 120 grams of carbohydrates an hour during exercise ignited the carbohydrate boom that was credited with helping cyclists, runners and triathletes race much faster. Viribay found that consuming more carbs promoted higher lactate availability in the body and thought that perhaps they can bypass the carbs and go straight to lactate utilization instead.

The original 'godfather' of lactate is Professor George A Brooks whose Lactate Shuttle Hypothesis in 1985 completely overturned the old belief that lactate (or lactic acid) is a "toxic waste product" of anaerobic metabolism, but an important energy source. 

When you exercise really hard, your fast twitch Type IIb muscle fibers produce lactate through glycolysis - the breakdown of carbohydrate. Brooks found that lactate does not just build up and fatigue, but is actually 'shuttled' (or transported) to slow twitch Type I muscle fibers, the heart and even the brain where it is converted into pyruvate and used to generate energy through aerobic metabolism.

Lactate also goes to the liver, where it is converted into glucose via the Cori cycle (a metabolic pathway where the liver and muscles work together to recycle energy during intense exercise). This newly formed glucose can be released into the bloodstream to help replenish energy supplies for working muscles or stored as glycogen when demand from working muscles is less.

The lactate does build up when exercising hard, and at some point the body cannot clear or reuse it, but it is the associated rise in hydrogen ions that slows you down and not lactate. 

This Lactate Shuttle Hypothesis by Prof Brooks provides the physiological foundation for Viribay's ExoLactate Gel (40 grams carbs with 1:1 ratio of glucose to fructose and 5 grams of lactate) and Enervit's C2:1Pro Lactate Gel used by Pogacar and UAE Team Emirates-XRG cycling team.

The gel works by sidestepping several metabolic steps so users enjoy an extra energy boost quicker by bypassing the glucose and frutose intestinal transporters at the heart of those 120 grams/ hour studies. Lactate is absorbed through a different transporter called monocarboxylate or MCT1.

Athletes that have reached a carbohydrate ceiling now has the potential of adding a complementary lactate energy boost without the 2 substrates (glucose and fructose) competing at the gut wall. One can then go faster for a longer time frame.

And there is more. Lactate is also a 'lactormone', a signaling molecule which kickstarts a variety of physiological responses to help the body adapt and grow back stronger. High lactate cranks up mitochondrial biogenesis (growth). 

Mitochondria are our cells' energy powerhouses. So more mitochondria means improved stamina, reduced fatigue and improved performance. 

It also means better cardiovascular function, insulin sensitivity and overall metabolic efficiency. This may even have implications beyond sports as increasing research links lactate to health and diseases. Ringer's lactate is already used in hospitals used to treat patient's low blood volume from trauma, surgery and burns. Gut microbiota that is more exposed to lactate from exercise are also healthier.

What about having a product that can mimic an exercise dose for someone who cannot move is a huge health potential. This is called 'exercise mimetics' where a drug mimics the biological effects without actually exercising. Kind of like a much healthier version of GLP-1 (Ozempic and Wegovy). Perhaps you can lose weight without exercising in the future. 

Will I try these new lactate gels? I am keen to try, but my first question is how they taste and what is it going to do to my stomach as gastrointestinal issues are one of the biggest concerns for endurance athletes when trying something new.

Will lactate gels offer similar breakthroughs similar to the high carb fueling trends we have seen? Is it for pros only or can most of us mortals also use them? You should already be training, sleeping and eating well, fueling correctly before exercising for best results, prior to trying. Those are the true pillars of performance.

Reference

Viibay A, Arribalzaga S, Mielgo-Ayuso J et al (2020). Effects Of 120 g/h Of Carbohydrates Intake During A Mountain Marathon On Exercise-Induced Muscle Damage In Elite Runners, Nutrients. 12 95): 1367. DOI: 10.3390/nu12051367.

Exolactate's version

Running Twice A Day?

Remember earlier in the year I wrote about how it wasn't really increasing total weekly mileage that caused running injuries. Instead, huge single session mileage increases known as "single-session paradigm" more likely caused injuries. That study (Frandsen et al, 2025) found that large jumps in a single-session distance predicted injuries much better than large jumps in weekly mileage.

The 5,205 runners were followed over 18 months and accumulated 588,071 run sessions. The authors found that instead of keeping your longest run to within 10 percent of your previous longer run, a 10-30 percent increase increased your injury risk by 64 percent. A 30-100 percent increase increased risk by 52 percent while more than 100 percent increase increased risk by almost 128 percent.

To increase mileage safely, instead of running say 10 km at a go, you can run 5 km in the morning and a second 5 km in the evening. Each 5 km run stays well within what your body can tolerate. Instead of doing one run further than what your body can normally handle, you can log more volume by running 5 km in 2 manageable sessions separated by many hours of recovery.

Moreover, a 5 km run definitely feels easier than the last 5 km if you are running the last 5km in a 20 km run. Your running form stays better, you have less fatigue and that second run may feel better after a stressful day at work.

When I used to race triathlons, I can run up to 15 km in the morning and then do another easy 5 km in the late afternoon. It allows me to log 20 km without needing to do all 20 km in the morning.

While it's not mandatory to run twice a day, it's probably one of the simplest and safest way to increase mileage compared to running as many days as you already can. Especially if that is your goal without getting injured.

Reference

Schuster Brant Frandsen J, Hlme A, Parner ET et al (2025). How Much Running Is Too Much? Identifying High-Risk Running Sessions In A 5200-Person Cohort Study? BJSM. 59 (17): 1203-1210. DOI: 10.1136/bjsports-2024-109380

Lots Of Volume Needed

A nice place to log some serious mileage

Previously I wrote that high mileage alone may not enough for you to run fast. Just because Sebastian Sawe clocked over 240 km a week leading to his sub-2 hour marathon does not mean you too have to clock huge distances to run fast. 

So this post is for serious runners. For runners who want and can log long distances. Runners who want to run fast and are prepared to spend lots of time running. The recommendations will not help weekend warriors who just want to complete a race or fitness influencers to quote this to their followers.

Here is what a comprehensive analysis of the training intensity distribution (TID) across runners from different performance levels looks like. Researchers looked at different training sessions from 16 weeks before 151,813 marathons (yes you read correctly), done by 119,452 runners.

TID was measured using a 3 zone approach (Z1, Z2 and Z3) where critical speed is defined the boundary between Z2 and Z3. Note that this IS different from the Zone 1-5 runners talk about. The Zone 2 most runners talk about is Z1 here and Z3 here is Zone 5 on that scale.

The transition between Z1 and Z2 was assumed to occur at 82.3 percent of critical speed. Critical speed is the maximum running speed you can maintain for 30 to 60 minutes without fatiguing rapidly. It is strongly correlated to your lactate threshold.The training characteristics and TID were reported based on the runners' marathon finish time.

Results show that training mileage was 45.1 ± 26.4 km each week. The fastest runners in the study group (marathon finishing time between 120-150 mins) ran greater than 3 times more volume than slower runners.They did not run fast often.

The amount of time spent training in Z2 and Z3 remained relatively stable across all performance levels, but the proportion of training time spent in  was progressively higher in faster runners.

More than 80 percent of the runners with faster marathon times had a pyramidal approach where the volume of training (mileage) decreases as intensity increases. Visually it forms a pyramid pictured below. A big base of easy Z1 running, a smaller middle section of moderate effort and a tiny peak of high intensity work. 

With regards to total mileage that the faster runners covered, the more time they spent in Z1 (really easy pace), the faster their marathon finish time (p < 0.01 - highly siginificant statistical finding, less than 1 percent chance this happened by coincidence). Moreover, R² ≥ 0.9, meaning over 90 percent of the variance in marathon finish times can be explained by looking at how much total volume the runner did and how much of it was in Z1.

The study also found that the more time a runner spent training at Z2 or Z3 intensities, the slower their marathon finish time. p < 0.01 and R² ≥ 0.85, at least 85 percent of the variance in slower finish times can be predicted by an over reliance on Z2 and Z3 training.

Focusing too much on hard and moderate efforts usually backfires. Why? Running too 'fast' on easy days and not hard enough on hard days means you are in the "grey zone". Not easy enough to get the aerobic adaptations needed and not hard enough to get the benefits of the high quality intervals.

Spending too much time in Z2 (moderately hard) causes higher fatigue levels without the beneficial effects of Z1 nor the high end fitness gains of Z3. 

The fastest runners in this study achieved their better times by increasing training volume mainly in Z1. They also ran less when they incorporated high intensity runs to allow for recovery. 

Is that true for all distances? What about a 5km or 10 km race? Will you still need to run lots of easy Z1 miles. If you want to simply finish the race, no. But if you consider that even a mile race of 5 km race is predominantly aerobic (pictured above) then you will understand why a large volume is needed to build a large base. 

Slower means more sustainable over time, you will not get injured so easily and hence more adaptation over time. That's how you will get stronger. 

Find more ways to increase your training volume with long easy runs. True aerobic developmnent is only possible from accumulating volume.  It allows you to recover and handle the key sessions. You cannot HIIT your way to the top. If you cannot get your hours in then it would be a lot more difficult to run faster.

Reference

Muniz-Pumares D, Hunter B, Meyler S et al (2025). The Training Insity Distribution Of Marathon Runners Across Performance Levels. Sports Med 55: 1023-1035. DOI: 10.1007/s40279-024-02137-7

Run Faster With Zero Drop Shoes

And we thought zero drop shoes were 'dead'. Zero drop shoes were all the rage after Christopher McDougall wrote about the Tarahumara Mexican Natives in his book, 'Born To Run', in 2009. Remember those Vibram shoes? Now, Vibrams I will classify as barefoot type and then there were minimalist type running shoes (or racing flats). Maximalist shoes have since replaced minimalist zero drop running shoes.

The research article I read was to determine if shoe heel-toe drop affects running economy. The researchers studied how shoe heel drop affects metabolic energy (total energy usage) in runners during running. 

20 runners were recruited for the study. Running speed was 3.5m/ sec (or 12.6km/ hr) in custom footwear that only differed in heel-toe drop of 0, 10, 20 and 30 mm. Running shoe and weight of the shoe were fixed with a US size 10, Air Pegasus. The heaviest shoe mass was the 30 mm shoe at 260 grams. Small weights were attached to the exterior heel of the shoes with the lower heel drops (pictured below).

During the research, the runners first did a standing 5 minute test and then ran for 5 minutes in their own running shoes at 3.5m/ sec (or 12.6km/ hr) on a force measuring treadmill (Treadmetrix). Each runner then completed a 5 min running trial at 3.5m/ sec in each of the 4 heel-toe drop shoe conditons in a randomized order. Participants rested at least 5 minutes between the runs.

To measure metabolic energy (or total energy usage), open circuit expired gas analysis was done to record oxygen and carbon dioxide uptake. Normalized net metabolic power (W/kg) was derived by subtracting the participants's corresponding standing metabolic power from each running trial and divided by their masses.

The results show that higher heel drop shoes increased plantar flexion in the ankles and knee flexion during ground contact. This we know from past research since runners who previously had knee pain had decreased knee forces and knee pain when they switched to zero drop running shoes.

Higher shoe heel-toe drop also increased metabolic power by 0.08W/kg per 10mm of heel-toe shoe drop.

One limitation in the study was that they only had one relatively large shoe size (US 10) which resulted in only one female participant in their study. Future studies may be warranted to test for potential effects between male and female runners.

Based on the researchers findings, they concluded that decreasing shoe heel-toe drop from 20mm to 0mm elicits a 1.6 percent more economical running which is predicted to improve total marathon performance by 1-3 minutes. 

Perhaps we will see the carbon plated maximalist running shoes come with zero heel-toe drop next?

Reference

Renninger K, Beck ON (2026). Shoe Heel-Toe Drop Affects Running Economy. J Appl Physiol. 141(1): 280-290. DOI: 10.1152/japplphysiol.00886.2025

27 Year Old Mile World Record Broken

I wasn't a fan of Josh Kerr before I read up on him while researching for this post. He always seemed too confident which many others (and I) interpreted as cocky. I realized what it really is, is a deep conviction that's founded in the work he and his coach Danny Mackey have done.

In front of 60,000 fans in the London Diamond League meet, Kerr ran 3:42.66 min to beat Hichan El Guerrouj's record set 27 years ago in 1999. 

Earlier in March this year, Kerr announced Project 222, an attempt to beat one of track's hardest and most hallowed record, El Guerrouj's 3:43.13 min mile world record. In typical Kerr fashion, he said: "It's time for that record to have a real go at it, and I'm going to be the guy to do it."

And he did it on 18th July! He etched his name into track and field history, joining previous UK legends like Bannister, Ibottsen, Coe, Ovett and Cram.

Both Kerr and his coach Danny Mackey are always methodical in their preparation, one of the reasons why Kerr always performs in the big meets where the lights are the brightest. Kerr won the 1500m world athletics championship gold medal in 2023, and was 3rd at the 2021 Tokyo Olympics and 2nd at the Paris 2024 Olympics in the 1500m. 

So difficult to do, but both Kerr and Mackey almost always get it right. A big part of that comes from how they approach training and performance. They know that consistency is what matters most.

They know that being consistent compounds. It is not having one super workout now and then. It is putting in the necessary work that prepares Kerr. 

While preparing for this, Kerr ran 2:42 min for a 1200m time trial at altitude, 5,355 feet in Albuquerque, New Mexico while being paced by Brannon Kidder, who also paced him in London. The last 400m done in 51.88 seconds. During El Guerrouj's world record run, he reached the bell lap in 2:47.9 with a lap to go (1209m).

Kerr says he "don't do crazy workouts or crazy mlileage. I just don't miss days. Consistency is my biggest weapon. I'll break any athlete down with how consistent I'm going to be training and just getting the work done." 

"The way that I get fast is stacking. I'm stacking years, I'm stacking days, I'm stacking months." "If you show up and put in the same level of effort regardless of how you feel, you're winning every day."

Sure he had 2 rabbits pacing him til 1000m. But he had to run the last 600m on his own. In those last 600m his 100m splits only varied between 13.7 and 13.9 seconds! Super consistent. One of the most impressive performances I've seen. 

Have a look at his official splits.

400m: 55.3 seconds

800m: 1:51.1 (56.8)

1200m: 2:46.5 (54.9)

1600m: 3:41.4 (54.9)

Finish (mile): 3:42.66 min. WR!!

It's even more amazing if you look at his splits by 100m.

100m: 13.8 seconds

200m: 27.5 (13.7)

300m: 41.0 (13.5)

400m: 55.3 (14.3)

500m: 1:09.3 (14.0)

600m: 1:23.2 (13.9)

700m: 1:37.0 (13.8)

800m: 1:51.1 (14.1)

900m: 2:05.1 (14.0)

1000m: 2:18.8 (13.7)

1100m: 2:32.6 (13.8)

1200m: 2: 46.5 (13.9)

1300m: 3:00.3 (13.8)

1400m: 3:14.0 (13.7)

1500m: 3:27.7 (13.7)

1600m: 3:41.4 (13.7)

Mile (1609.34m) : 3:42.66 min (1.2 sec for final 9.34m)

https://x.com/_OwenM_/status/2078491974399574210 - watch the video

Picture from Letsrun.com

Day 2 Of Kinesio Foundations Course

Most of the participants left some of the Kinesio taping done on Day 1 on them throughout the weekend. We went through how that felt so they can better understand how patients feel with tapes on after they leave to go home. Everyone felt that the taping had good results.

We then started Day 2 with the Kinesio Corrective Techniques. The occupational therapists in the class requested for a few scenarios for the upper arm and shoulder after a patient has a stroke and we covered that too, even though that was not in the syllabus.

We left more time at the end to do the Jelly fish and the epidermis, dermis and fascia (or EDF) techniques. The participants took their time as those techniques needed lots of focus and handling skills.

Doing the jellyfish taping

A big thank you to all the participants, my family and colleagues for helping out. Could not have done it without all of you. Stay tuned for the next course most likely in mid 2027.

Kinesio Foundations Course Day 1

Sports Solutions hosted Day 1 of the Kinesio Foundations Course today. We have occupational therapists, physiotherapists, a medical doctor, a yoga instructor in our class this time.

With Dr Sangita and Sarah

Stay tuned for Day 2 tomorrow where there is a bigger emphasis on the Kinesio Medical Taping section instead of just the Kinesio Taping Methods where muscles, joint and tendons were the main focus. 

Some of the techniques include the Space Correction and webcut applications for bruising and swelling. We will also do the EDF (epidermis, dermis and fascia) and jellyfish taping. 

None of the other brands of tape have any of those techniques mentioned above.

Tarsal Tunnel Syndrome

Picture from Orthopaedia.com

A patient came in to our clinic declaring she has plantar fascia pain in her right foot. She had seen another physiotherapist a few years ago for plantar fascia pain in her left foot and had gotten better. This time she tried orthotics, lots of stretching and even shockwave (or ESWT) with the same physiotherapist, but there was no improvement.

This is how she described her foot pain. She said there was a burning, aching pain at the bottom of her foot and on the inner heel. She said it almost feels like an electric shock. Her pain gets a lot worse after prolonged standing and sometimes wakes her up at night. She also gets numbness in her toes. 

None of those symptoms sound like plantar fascia pain to me. Patients with plantar fasciitis usually have pain during the first few steps when they get out of bed in the morning. There is rarely numbness, burning or electric shock sensations in the toes.

Upon assessment, there was no pain on the posterior calcaneal tubercle (where the PF inserts) nor along the plantar fascia itself. 

I elicited her pain when I did a modified Straight Leg Raise test by holding her foot in full dorsiflexion and eversion. However, there was no tingling or zinging in the foot when I tap on the medial malleolus (over the tarsal tunnel) - also known as Tinel's test. Online articles often describe a positive Tinel's test.

I explained my findings to her. My patient actually has Tarsal Tunnel Syndrome. This is when the posterior tibial nerve gets 'trapped' and irritated in the tarsal tunnel at the inner part of the foot (pictured below). 

Picture from Teachmeanatomy

The tarsal tunnel is a space just behind and below the medial malleolus and serves as a passageway for the posterior tibial artery, nerve and what we call Tom Dick and Harry muscles (tibialis posterior, flexor digitorum longus and flexor hallucis longus). The 'roof' of this tunnel is covered by the flexor retinaculum. It is a thick and strong fibrous band that holds Tom, Dick and Harry in place.

Tom, Dick and Harry- back of R leg

Entrapment of the posterior tibial nerve in the tarsal tunnel caused my patient's foot pain, not plantar fasciitis.

Online or AI* searches always say that flat feet or severe overpronation can cause tarsal tunnel pain as it can stretch the nerve although my patient does NOT have flat feet.

My patient did have a severe right ankle sprain a few months ago that caused swelling and perhaps thickening in the connective tissue in the tunnel that eventually caused this. It was also not treated properly, causing her to compensate and stand and walk differently possibly 'tractioning' her posterior tibial nerve.

A ganglion cyst in the canal may also cause this since it reduces the space in the tunnel. I have never come across this though in the 27 years of being a physiotherapist.

When a patient complains of bottom of foot pain, plantar fasciitis is usually the diagnosis one thinks of. The symptoms of tarsal tunnel syndrome pain can be similar to lumbar radiculopathy, diabetic and peripheral neuropathy or plantar fasciitis. Hopefully this article will correct that. 

 (*All the articles in this blog are written by me not by AI).

Reference

Boers N, Haverkamp M, Eligh AM et al (2026). Differences in Diagnosing Tarsal Tunnel Syndrome Across The Literature: A Systematic Review And A Call For Standardization. JBJS Rev. 14(2): e25.00222. DOI: 10.2106/JBJS.RVW.25.00222

L flexor retinaculum

Picture from https://drjustindean.com/retinaculaofthefoot/

Can Cross Training On A Bike Translate To Better Running Performance?

Picture from Bikatadventures.com

I had shin stress fractures in both legs from running too much when I was 20. The doctor I saw said that I could not run for a minimum of 6 weeks. I could only swim or bike. It was this cross training regime that got me started in triathlon later.

This concept cross training emerged in the 1980s along with the popularity of triathlon. Earlier studies reported that performance in a primary sport can be maintained despite reductions in volume of the primary sport by training in a variety of sports. These findings suggest potential crossover effects between endurance training modalities. Are these findings still relevant?

The following systematic review by Menges et al (2026) compared the effects of running only and cycling only training interventions to evaluate cross training transfer to sport specific VO2 max and running performance.

The authors found 7 studies with intervention durations of at least 4 weeks. These were run only training with cycling only or combined running-cycling interventions. Outcomes included VO2 max assessed on a treadmill or cycle ergometer as well as running time trial performance for 1 mile, 3000m and 5000m.

So does cross training on a bike help running performance? This meta-analysis suggests it does. The subjects who performed run only, bike only or combined running and cycling training performed similarly in the 1 mile, 3000m and 5000m time trials. They also had improved VO2 max values regardless of testing method (treadmill or cycle ergometer).

Cycling engages the quadriceps and gluteus maximus muscles in ways that running does not. When the muscles get stronger, it helps improve running economy and power (especially in hilly races).

Instead of running twice a day, you can take away some of the extra strain on the legs by cycling (or even training on the elliptical machine) without the repetitive impact forces of running. This is especially beneficial during recovery periods or for runners prone to injuries.

Cycling is low impact which is great for your joints. However, it does little to help your bone density. Running on the other hand has impact loading that helps to maintain or even increase bone strength which is great for older athletes.

The findings should be interpreted with some caution since there were limited studies (7) and the fairly short training period.

For shorter distances up to 5 km at least, there may not be any differences but in a longer event like the marathon, you still need to run since the run muscles will not used as much while cycling. Biking can definitely help the aerobic fitness but not the specific leg muscles, and running performance may decline.

Running and cycling can actively enhance each other when integrated carefully. If you're a runner looking to improve your endurance without extra impact or a cyclist looking for stronger stabilizing muscles, cross training helps.

The key is balancing both to meet your specific training goals while avoiding overuse injuries.

The principle of specificity suggests that cross training can offer general fitness benefits, the most significant performances are achieved through sport specific training. Before Sabastian Sawe broke the 2 hour barrier for the marathon, he was running in excess of 200 km a week in the 6 weeks leading up to London, with a maximum of 241 km (150 miles). 

So, runners and cyclists should incorporate cross training as a supplementary activity rather than a replacement for their primary sport.

References

Menges T, Dindorf C, Dully J et al (2026). Cross-Training Between Rnning And Cycling: Effects On VO2 Max And Running Performance- A Systematic Review And Meta-Analysis. Front Sp Act Living. 8: 1843803. DOI: 10,3389/fspor.2026.1843803

Tanaka H. (1994). Effects Of Cross-Training. Sports Med. 18: 330-339. DOI: 10.2165/00007256-199418050-00005

Carbon Plated Shoes And Stress Fractures

Picture from Prodirectsport

I just saw 3 different people wearing carbon plated shoes at the Cold Storage in Holland Village. They were shopping for groceries and definitely not running. On one hand you have someone like me who's still unwilling to run in carbon plated shoes while on the other hand they are a dime a dozen amongst runners now (and people walking in Cold Storage). Most runners use them in training as well, not just at races. 

No running study has studied whether carbon plated shoes (known as advanced footwear technology or AFT) changes running biomechanics associated with bone stress injuries (BSI), or shin splints. The researchers goals were to measure running biomechanics while running in an AFT shoe.

23 runners (11 women, 12 men) with an average age of 25.4 ± 2.7 years were recruited for the study. They ran randomly in 3 different types of running shoes, neutral, lightweight (responsive foam) and AFT at 3 self selected running speeds. A run at their 'training effort', a tempo run and at 5 km race pace.

Biomechanical variables associated with BSI such as cadence, vertical ground reaction forces, ankle and rearfoot eversion forces were measured during each run and shoe condition.

Results show that with neutral running shoes, ankle plantarflexion moment was higher compared to lightweight foam and AFT. There was less rearfoot eversion movement in the neutral shoe compared to lightweight foam and AFT. 

Cadence was lower while running in AFT shoes  compared to neutral or lightweight foam shoes. This is relevant since a longer running stride has been linked (in earlier studies) to BSI in the lower limbs.

Rearfoot eversion velocity (the speed at which your foot rolls down and inwards), or pronation was higher in the lightweight foam shoe compared with both neutral and AFT shoes. There was no significant difference in this between the neutral and AFT shoe.

The authors concluded that there were increases in several biomechanical variables associated with BSI  while running in AFT shoes. Although these changes were small, they tend to accumulate and can contribute to increased forces on bones in the lower limbs.  

The authors suggest that rotating running shoes and gradually using AFT to adapt to the differences may help reduce potential injury risk while optimizing running performance.

Reference

Bruneau MM, Gaudette LW, Sirls E et al (2026). Biomechanics Associated Withe Bone Stress Injuries While Using Advanced Footwear Technology In Elite Distance Runners. PM & R. 18(2): S143-150. DOI: 10.1002/pmrj.70153

Repeat The Same Training?

I started keeping a handwritten training log (pictured below) after I started running at 13. Back then there were no apps to keep such records for you. I would record how far I ran, time taken, how I felt, what shoes I used, etc. 

I found it useful so I could look back on what training I did when taking part in a similar event. Say my key interval workout for a 1500m track race that I had won previously was 8x200m with 30 seconds rest. I would replicate those sessions along with deciding if I could handle more. Back then, I was a teenager and was able to run personal bests in all my events every year.

I assume that when I responded well to a training program once, I'd respond similarly or better the next time. However, a recent study suggested otherwise.

A group of researchers had subjects do the same 8 week endurance training program twice, but separated by a period of detraining that had to return to baseline. 42 out of the 53 recruited completed the study.

Each 8 week period had 24 supervised 45 minute interval cycling sessions at moderate to maximal intensity. Identical training instructions were applied such that the same training program was repeatedly prescribed to the same individuals. Exercise intensity was individually prescribed relative to performance and adjusted every second week to mainatin a comparable training stimulus across periods.

Results show very poor reproducibility of adaptation. One athlete increased VO2 max by about 600mL min⁻¹ after the first training period. However, there was no improvement at all after the second training period. Yes you read correctly, zero improvement.

Same athlete, same program, but very different outcome. I asked a few coaches whom I treat if this was similar to the athletes they coach. They told me they see it all the time. Training response varies.

The training may be the same but the variations in external factors such as sleep, diet, work stress, travel and illness contributes to the variability in individual training adaptations.

That's what the researchers concluded too. The substantial within-individual fluctuations were largely consistent between training periods and they suggest that this  within-individual fluctuations does not reliably reflect their capacity to adapt to the same training stimulus in the future.

So low stress plus good training leads to adaptation while high stress plus the same training may lead to very different outcomes.

Take away message? Do not assume that because a program worked once, it will work the same way the next time. Monitor the state of your own life stresses and modify accordingly.

Reference

OddenIV, Hamarsland H, Odden TU et al (2026). Limited Reproducibility Of Individual Physiological Adaptations To Repeated Endurance Exercise Training. J App Phy. DOI: 10.1152/japplphysiol.00154.2026

Can You Trust AI With Nutritional And Athletic Performance Advice?

Picture from Sixminutemile.com

I was reading about how 2024 Olympic road race cycling winner Kristen Faulkner built her own artificial intelligence (AI) model to analyse 9 years of her own performance data to help her uncover what's missing from women's sports science. It allowed her to have data that helps explain not just what happened but why.

Faulkner said she coded to build the AI technology that can learn from data, spot patterns and make decisions. These are skills that we usually associate with human intelligence. 

AI is already in our everyday lives. We get Google Maps directing our commute, Spotify suggesting songs on your playlist and hit ChatGPT with any question we might have.

Many people use AI for everyday health, exercise and medical queries. Are these AI driven chatbots reliable and accurate? Our patients already use AI to self diagnose their pain and injuries. Some studies show chatbots are largely accurate, while others reported frequent errors and even a risk for transmitting inaccurate information.

The following research investigated 5 popular AI driven chatbots to evaluate their responses to everyday health and medical queries across 5 categories: cancer, vacines, stem cells, nutrition and athletic performance. Both open ended and closed ended questions were used.

Gemini, Meta AI, DeepSeek, ChatGPT and Grok were the 5 chatbots used. They were each presented with 50 prompts across the 5 topics mentioned above. The researchers used an adversarial framework to strain models towards misinformation or contraindicated advice.

An adversarial framework refers to a system, process or analytical model structured around opposition, competition or conflict. This is a cybersecurity approach used to test the vulnerabilities of AI systems.

Responses were then independently rated by 2 domain experts as non-problematic, somewhat problematic or highly problematic. Citations were assessed for authenticity and completeness while readability evaluated using the Flesch Reading Ease score (100 point scale with higher scores being easier to read).

Results showed that nearly half of ALL responses (49.6 percent) were problematic, 30 percent somewhat and 19.6 percent highly problematic. Nutrition and athletic performance topics had the weakest performance and Grok generated significantly more highly problematic responses than expected.

Reference quality was poor across all chatbots. The median completeness score was 40 percent. No chatbot came up with a fully accurate reference list. Misleading, unreliable or fabricated citations were common. So please be careful if you use them.

All the 5 chatbots produced responses that were rated "difficult" on the Flesch Reading Ease scale, equivalent to university-level reading. Chatbots answered consistently with confidence regardless of accuracy, while rarely declined to respond (2 refusals to answer across 250 total responses).

The researchers concluded that continued deployment of AI chatbots without public education and regulatory oversight risk amplifying health misinformation. Especially in the field of nutrition and athletic performance. They also suggested that public education, professional training and regulatory oversight to ensure that generative AI support rather than replace professionals.

My suggestion when searching for health information is to treat these AI chatbots with a good amount of skepticisim and to verify information with qualified professionals or peer-reviewed sources. There will be some benefit seeking ideas and initial information from a chatbot, but beyond that you will need a real human expert.

Reference

Tikker NB, Marcon AR, Zenone M et al (2026). Generative Artifical Intelligence-Driven Chatbots And Medical Misinformation: An Accuracy, Referencing And Readability Audit. BMJ Open. 16(4): e112695. DOI: 10.1136/bmjopen-2025-112695.

New Way Of Grading ACL Tears

A group of researchers have introduced a new way of grading anterior cruciate (ACL) tears that are relevant to ACL healing potential. This is based on the results of managing 1080 active individuals and athletes using the Cross Bracing Protocol

Remember the Cross Bracing Protocol (CBP)? These are patients who are managed conservatively without surgery, they are put in a brace to allow ACL healing to occur.The injured knee is kept at 90 degrees of knee flexion to reduce the gap between the ruptured ACL remnants. Research shows that 90 percent people regain continuity of the fibers after 3 months of treatment in the CBP. 

Yes, the torn ACL can heal when both ruptured ends attached to each other while the knee is in a bent position. However, more severe ruptures are the least likely to achieve optimal healing.

Not all ACL's that heal (or regain continuity of fibers) in studies had a normal appearance on MRI. 50 percent of subjects in the KANON trial had a normal appearance ACL, the other 50 percent had a thinner/ elongated continuous ligament (Filbay et al, 2023). 

56 percent of those with a continuous ligament 3 months post CBP treatment had a thick ligament with normal course. The other 44 percent had a thinned/ elongated continuous ligament.

In this currrent study, subjects with a thick ACL with normal course at 3 months had better 12 month outcomes when it came to knee function, quality of life and return to sport.

In addition, the following characteristics may affect the likelihood of achieving an optimal healing outcome. Patients with partial avulsion of ACL tissue from the femoral attachment are more likely to have a suboptimal healing or even no healing compared to those with the femoral origin intact (pictured above).

Displacement of the ACL ligament outside the intercondylar notch is also associated with suboptimal healing when managed with CBP. This may be due to a significant disruption to the synovial sheath that encapsulates the ACL. Disruption of this sheath negatively impacts healing potential.

If the distance of the gap between the 2 ends of the ruptured  ACL is too wide (assessed by measuring the largest distance between the torn ends of the ACL), optimal healing is less likely to occur. Among the first 80 people in this study, 7 out of 40  (18 percent) patients achieved a thick/ taut ligament healing had a gap of ≥7mm on MRI.19 out of 32 (59 percent) had a thinned/ elongated ligament while 7 out of 8 (88%) had no ACL healing at 3 months.

When one or both ends of the ACL stumps appear rounded or retracted, also know as ACL involution, it is usually the early stages of a 'non-heal' and may correspond to poor or no healing. This is observed commonly in patients who present for MRI more than 3 weeks post ACL tear.

Besides the above, meniscal injuries, another ligament injury, articular cartilage damage, osteoarthritic features, bone bruising and joint swelling may also affect the likelihood of achieving optimal healing.

The authors concluded that with further research they may be able to assist people in making an informed treatment decision of the likelihood of individuals achieving optimal healing with nonsurgical management.

Reference

Filbay S, Dowsett M, van Haeringen M et al (2025). A New Way Of Grading Severity Of ACL Rupture On Acute MRI To Consider Potential For Noin- Surgical Healing With Cross Bracing Protocol: ACL Acvute Rupture  Characteristics For Healing (ACL-ARCH) MRI Criteria. J Sci Med Sp. 29: 145-148. https://www.jsams.org/article/S1440-2440(25)00411-6/fulltext

Is Your Evening Workout Costing You Sleep?

Picture from Sitnsleep.com

I read that the Kenyan runners usually ran at least twice a day. The first run when it's still dark between 6 to 630 am to beat the heat. It is usually an easy progressive run though sometimes long runs or fartleks can take place. 

A second session often takes place between 10-11 am. This is usually reserved for track interval sessions. Typically they do 2-3 key interval sessions a week with most of the runs really easy so they can recover. When asked why they do the second run before lunch, the reply is so that they have more time to recover before the next day's sessions. 

Sometimes they even do a lighter recovery run between 4 to 5 pm to add to their weekly mileage.

So I was not surprised when I read that the timing of our workouts can affect our sleep (Akhtar and Eleftheriou, 2026). To avoid confounding factors, sleep and activity data from the same day through a model with fixed effects and terms for activity time, activity-sleep gap and the interaction between these terms. 

Data collected from users sleep looked at how sleep was affected by when they decide to exercise. The focus was on cardiovascular exercises, specifically walking, running (outdoor and treadmill), cycling (outdoor and stationary) and hiking. They studied over 100,000+ workout sessions and found that the later you train, the worse you recovered (pictured above).

When you exercise later in the day, your sleep heart rate is higher, your heart rate variabilty (HRV) is lower and you get fewer REM sleep events. You may sleep quicker with later workouts, but it is not better sleep. It is falling asleep faster while recovering less.

The benefits plateau around the 10 hour mark. The sweet spot is a 11 to 14 hour gap between your workout and bedtime. If you can exercise earlier in the day, you can capture most of the benefits. Perhaps that's the reason the Kenyan runners do their second run at 9 am. 

What about those people who can only exercise at 8pm onwards or later? Should you worry about this?  My take is no. Majority of people should NOT worry. I think it is more important to exercise where it fits in your life. 

Don't worry too much about HRV scores or perfect recovery. You are only working out at 8 pm or later because that's the only time when family and work gives you an opportunity to. Many people do not have the luxury to choose the time to exercise and exercising at any time is better than no exercise.

Our bodies are remarkably adaptable too. I am sure if you exercise at 8 pm or later long enough your body will get better sleep. Not perfect sleep but the detriment is less.

Showing up and exercising is way more important than perfect conditions. Consistency beats optimization every time. That is what will compound.

Reference

Akhtar F and Eleftheriou K (2026, May 24). Your Evening Workout Is Costing You Sleep. Terra API. Https://trryterra.co/research/best-time-toworkout--for-sleep#the-honest-takeaway

Warming Up Body And Mind

Picture from Healthywomen.org

All of us are familar with warm ups. Before you run, exercise and especially before a race. You are trying to increase your core temperature, send more blood flow to the limbs and 'wake' the muscles up. Before a running race you may even try some race pace striding so the actual start of the race does not feel like a shock.

So I was surprised to read that combining mental and physical warm ups can improve running times. Curious? Please read on to find out more.

Researchers in that study investigated whether combining cognitive tasks with a standard physical warm up could improve 1-mile performance in runners. 25 runners (11 male, 14 females) with an average weekly mileage of 20 miles (32 km) and 5km personal best timing of 23:31 min were recruited for the study. Each runner completed 3 separate testing sessions.

First was with only a physical warm up which included a 1200m easy jog, 800m alternating 100m jogs and 100m strides and 3 minutes of active stretching drills. 

Next was the same physical warm up plus a low load cognitive task and finally same physical warm up with a high load cognitive task.

In the cognitive warm up conditions, the runners completed four 3-minute cognitive tasks before and between the physical components.These tasks targeted mental functions like switching between tasks, decision making, inhibiting responses to stimuli and memory. They were doing short bursts of focused mental work designed to activate the brain without exhausting it.

 

After that all the runners ran 4 laps of a 400m track with their watch face covered so that they could only rely on feel rather than constant pace feedback.

Ready for the results? The runners were faster after both cognitive plus physical warm ups compared to only doing the physical warm up. The  low load cognitive task improved 1-mile timing by about 8 seconds (2.3%),  while the high load cognitive task improved performance by about 11 seconds (2.8%).

The runners did not appear to muscle their way to faster timings since their perceived effort was lower after the combined warm ups and their average heart rate during the time 1-mile run was also lower. Their readiness to perform was higher, meaning the runners felt more prepared to run hard.

Stride length and cadence did not change meaningfully suggesting that performance boost was not explained by obvious mechanical changes.

Take home message? No, you do not need to download an app to challenge your cognitve skills before every workout or race. However, this study does suggest that the best warm up should prepare both mind and body.

Before you do your track interval sessions, time trials or short, hard and fast sessions or even up to a 5 km race, it may be useful to add a small cognitive task that perhaps include coordination games, quick reaction tasks, fast feet with visual cues to make you engage attention before you start running hard.

The important thing to note is dose. A few short mental tasks coupled with jogging, drills and race pace striding may help you feel sharper and more ready for your workout. A long, draining task may do the opposite.

This sharpens the nervous system rather than stressing your brain. Keep it brief and engaging and please try it in your training first before trying it on race day.

Reference 

Mortimer, H Dallaway N, Diaz-Garcia J et al (2026). Warming Up The Body And Mind: Bombined Cognitive And Exercise Priming Improves 1-Mile Time Trial Performance In Recreational Runners. Eur J Sp Sci. 26(5): e70163. DOI: 10.1002/ejsc.70163