Improve Your Running Economy Durability

Remember my post for runners who want to log long distances so that they can race well? Here's another benefit for running longer.

Runners with regular long runs tend to hold their form and keep their running economy better late in a run. Running economy durability becomes better.

If you have high running economy, your body uses less oxygen and burns less carbohydrates when running at 6 minutes per kilometer pace. If you have low running economy, your body is less efficient and has to work harder and burn through more carbs to maintain that same 6 min / km pace. 

When you start running, your body is fresh and highly efficient. As the minutes and miles go by, your muscles fatigue, your running form deteriorates and your systems have to work harder. Running economy durability is your resistance to this degradation over time.

Consider the following study by Zanini et al (2026). Two groups of 13 male runners were recruited as long distance training (LDT) or short distance training (SDT) runners. The LDT group of runners had regular long runs ≥ 90 mins while the SDT group had all their runs under 70 mins.

Both groups of runners were first assessed to determine their lactate threshold and maximal oxygen uptake. On another day, they then did a 90 minute run at lactate threshold. Lactate threshold here is the running pace (or exercise intensity) where lactate begins to accumulate in your bloodstream faster than your body can clear. It represents a boundary line between sustainable effort and unsustainable exhaustion.

Respiratory gases were collected and assessed every 15 minutes. Isometric squat peak force and counter movement jump values were assessed before and after the run.

When matched for 10 km performance, the LDT was faster (39:00 versus 39:10 min), had higher maximal oxygen uptake (58.9 versus 56.6 mL kg⁻¹ · min⁻¹). The LDT runners lost 3.1 percent running economy over 90 minutes versus 6.0 percent for the SDT runners. 

Results show that SDT runners had greater losses in running economy, isometric squat force and jump power compared to the LDT running group of runners. Running economy durability also correlates significantly with weekly training volume and length of the weekly longest run rather than muscular fatigue.

This study shows that long runs and higher training volumes positively affect running economy durability and protects a runner's aerobic efficiency over time. So even if there are 2 runners who can run a fast 10 km at the exact same pace, the runner who skips or does not do as many long runs will burn through significantly more energy and experience drastically higher muscle fatigue as the duration of an event stretches past the one hour mark.

Want to run a personal best in a marathon (or any long event), make sure you do your long runs regularly and race pace training.

Reference

Zanini M, Folland JP, Blagrove RC. (2026). Regular Long Runs And Higher Training Volumes Are Associated With Better Running Economy Durability In Performance Matched well-Trained Male Runners. Med Sci Sp Ex. 58(1): 162-173. DOI: 10.1249/MSS0000000000003840.

Why We Ask If You Drink Alcohol?

One of the questions we always ask our patients when they see us for the first time is whether they smoke or drink. This past week, I had a patient who gave me a 'none of your business' kind of look when I asked that question. 

I told him actually it is none of my business whether he smoked or drank. The only reason we ask that in our clinic is that both can affect tissue healing. Smoking dries and dehydrates our interstitial spaces and connective tissues. Alcohol has an inflammatory effect and damages articular cartilage.

Surprised? Consider a prospective Osteoarthritis Initiative study that studied 2,846 participants (between 45-79 years old) and most importantly had no radiographic (or x-ray) evidence of knee osteoarthritis (OA) in at least 1 knee at baseline. These participants were followed for 96 months.

The researchers investigated for incident cases of radiographic knee OA as Kellegren-Lawrence grade changing from zero or one to ≥ two during the follow-up period. Incident symptomatic OA was defined as radiographic knee OA with knee pain worsening. 691 knees with incident radiographic OA knees were identified and 496 knees with symptomatic OA were found among the subjects.

Baseline information on alcohol consumption were obtained using the Block Brief Food Frequency Questionnaire. 

Drinking 30 grams of alcohol a day or more (about 2-3 drinks) was associated with a 93 percent higher risk of radiographic knee OA and 61 percent higher risk of symptomatic disease versus non drinkers. A similar result was observed for liquor spirit consumption (pictured above).

The underlying mechanism between between alcohol consumption and OA onset is still controversial. An animal study demonstrated that chronic alcohol consumption increased the articular cartilage breakdown enzymes (MMP-13, ADAMTS-5) in both shoulder and knee joints in mice. They also suppressed the molecules that protect articular cartilage.

The authors concluded that excessive alcohol consumption (≥30 grams/ day) was significantly associated with an increased risk of developing both knee structural changes and clinical knee joint pain. Light to moderate drinking showed no measurable negative impact on knee OA development in this study.

Light to moderate drinking data was mixed for other factors. What we know is not mixed is alcohol also disrupts sleep, triggers inflammation, adds empty calories which affects every other healthy knee arthritis habit.

Now you know why we ask about smoking and drinking. Especially if you have knee pain.

Reference

Liu T, Xu C, Driban JB et al (2022). Excessive Alcohol Consumption And The Risk Of Knee Osteoarthritis: A Prospective Study From The Osteoarthritis Initiative. Osteo Cartilage. 30(5): 697-701. DOI: 10.1016/j.joca.2022.01.011

And there is an article on drinking less alcohol in the Sunday Times today too.

Rotator Cuff Tear

A patient sent me a message yesterday regarding her shoulder. She had slept poorly and woke up with some shoulder discomfort. After seeing her doctor, he referred her for a scan. Her MRI shows a tear in the supraspinatus muscle (part of the rotator cuff) and some osteoarthritic changes in the joint. She was worried about the tear. It got scarier when her friends told her that if she did not "fix it" the tear would become worse and her shoulder would wear out.

I told her about a recently published study done where 602 participants had  scans done on both shoulders. (Ibounig et al, 2026). Median age of the participants was 59 (range from 41-76 years old) and 52 percent were female. 

Rotator cuff abnormalities were found in 98.7 percent of painful shoulders. There were 25 percent with tendinopathy, 62 percent partial thickness tears and 11 percent with full thickness tears (FTT).

More importantly, rotator cuff (RC) abnormalities were seen in 96 percent of pain free shoulders. Full thickness tears of the RC were in 7 percent of shoulders that did not hurt. 

The prevalence and severity of abnormalities increased with age, but did not differ between sexes. 

Only FTT were more prevalent in painful shoulders (14.6 percent) than in non-painful shoulders (6.5 percent). However this difference decreased after "adjustment" (absolute difference, 0.8%; 95% CI, -3.4% - 6%). This means that once the researchers accounted for age, the apparent link between having shoulder pain and a FTT vanished.

At first glance, FTT looked more common in painful shoulders (14.6%) versus non-painful shoulders (6.5%). However, older people are more likely to have shoulder pain and a FTT just from normal aging.

"Adjustment" is a statistical technique that levels the playing field as it allows reserachers to compare painful and non-painful shoulders of the exact same age. When they did this, the true difference was just 0.8 percent. This is a very tiny margin, meaning the presence of a tear does not reliably explain why a shoulder hurts.

95% CI, -3.4%-6%. When the confidence interval (CI) crosses zero (goes from a negative to positive number), it means there is no statistically significant difference. The negative side means it is statistically possible that FTT are actually less common in painful shoulders by 3.4 percent.

The positive side means it is statistically possible FTT are more common in painful shoulders by 6 percent.

The math proves that one cannot look at a FTT on an MRI an automatically assume it is the cause of someone's shoulder pain. A person with a painful shoulder is statistically no more likely to have a full thickness tear than a person of the same age with completely pain free shoulders.

I told my patient that her 'abnormalities' on the scan were actually just aging. What matters most for her (and others) is function. Is there weakness and/ or pain when she moves her shoulder?

Can she sleep without pain and can she play pickleball without pain? If all her answers are no, she most likely will NOT need an operation. Just because abnormalities are seen on MRI does not mean it can cause pain or needs to be fixed.

Reference

Iboinig T, Jarvinen TLN, Raatikainen S et al (2026). INcidental Rotator Cuff Abnormalities ON Magnetic Resonance Imaging. JAMA Intern Med. 186(4): 406-414. DOI: jamainternmed..2025.7903

Best Way To Train For Hyrox

Photo by CNA/ Marcus Mark Ramos

Yesterday I had a patient who's training for her second Hyrox competition coming up this November.  She has been going to the gym and participates in their Hyrox training program 5 times a week. The sessions are mostly strength sessions with simulated practices of lunges, farmers walk, wall balls and other strength training. There is very little running, rowing or cardio during these sessions. I mentioned 8 km of running is involved and I suggested that being able to run well when tired will allow her drop her time significantly. 

I also shared with her an article that was published last year that analyzed, in depth, the physiological responses and performance factors in Hyrox (Brandt et al, 2025).

Here are the numbers that matter and the requirements needed. On the rate of perceived exertion (RPE) on the Borg scale, participants rated it as 18 out of 20 difficulty. Average time the study participants took was 1 hour 26 and half minutes. 

Average heart rate during the event was 171 beats per minute. That's very high, easily above the 90 percent of maximum heart rate for probably everyone. In fact during 79 percent of the whole event, participants are competing at intensities of 90-100 percent of their maximum heart rate.

What set apart the better performers? VO2 max showed a strong relationship with finishing time. Spearman's rank coefficient was p = -0.71. It explains how critical an athlete's aerobic fitness is to their race success. Yes you read correctly, it's aerobic fitness, not strength. In exercise science, a correlation of 0.71 is considered strong. It proves that aerobic capacity (or fitness) is not just a minor factor, but a primary driver of performance.

In contrast, neither hand grip strength (a good predictor of work efficiency and fatigue management during sled pull, farmers carry and sandbag lunges) nor muscle mass percentage were good predictors. Hand grip strength also correlates with strength in other muscle groups and is used as a predictor for total muscle strength.

While variables like strength, pacing and transition speed matter, your raw capacity to absorb and utilize oxygen (VO2 max) is one the most reliable predictors of how fast you will finish the Hyrox event.

The negative sign indicates an inverse (or opposite) relationship, as an athlete's VO2 max increases, their race time decreases. This means they finish faster.

Recommendations for training?

According to the authors, endurance training should be emphasized at moderate intensities as well as forms of HIIT (high intensity interval training) to improve both aerobic and anaerobic capacity. Since 8 km of running is involved, a substantial amount of training volume needs to be dedicated to running based sessions. 

Since excessive running mileage can increase injury risk, a strategy would be to replace or combine running with Hyrox specific endurance activities like rowing or skiing. Combining running with other Hyrox requirements should be an integral part of Hyrox training to improve running economy in a pre-fatigued state and will help with ability to transition between different metabolic demands.

Even though strength appears to be less important, participants still need to be able to move external weights as per competition standards. Previous research indicated that endurance and weight training may interfere with each other if done together, affecting adaptations. To minimise interference, separating strength and endurance into distinct sessions. If both are done together, the more important aspect should be trained earlier.

It is not enough to run fast in isolation. Not enough to just be strong either. You have to be able to keep running fast after you have rowed, pushed the sled, done wall balls and lunges etc. And to repeat it over and over again.

Your aerobic (or cardiovascular) engine, running and the ability to maintain performance while fatigued is crucial.

"More running?" My patient said. Definitely I said, at least more than what you have been running so far, since you have doing lots of strength training previously.

Reference

Brandt T, Ebel C, Lebahn C et al (2025). Acute Physiological Responses And Performance Determinants In Hyrox- A New Running-Focused High Intensity Functional Fitness Trend. Front Physiol. 16:1519240. DOI: 10.3389/fphys.2025.1519240