Does Better Fitness Protect Us From Dementia And Depression?

I'm not a mental health expert. I only know that I always feel better after I run, cycle or do any other form of exercise. Especially if I've been particularly stressed about something or everything.

We know for sure that having good cardiorespiratory fitness is a strong indicator of overall physical  health. However, is someone with good cardiorespiratory fitness less likely to have mental health disorders or dementia later in life?

A newly published systematic review and meta-analysis provides new updates on this link across all age groups in their study (Diaz-Goni et al, 2026). 22 studies (out of 27 chosen) with 4,007,638 participants were studied in that review. 

The participants were between 18 and 64 years old, who had fitness measured at baseline and followed for 4 to 29 years. Different methods were used for measuring fitness. Some studies used VO2 max, others used indirect or submaximal exercise tests while others measured peak workload and exercise duration. Note that this paper talks about cardiorespiratory fitness and NOT about VO2 max values.

Higher cardiorespiratory fitness was associated with substantially lower future risk of depression, psychotic disorders and dementia. However it did not show to clearly help with anxiety.

Each 3.5 mL/kg/ min (or 1 MET) increase in cardiorespiratory fitness was associated with a 5 percent lower risk of depression and 19 percent lower risk of dementia.

Overall, those with higher cardiorespiratory fitness had a 36 percent lower risk of depression, 39 percent lower risk of dementia and 29 percent lower risk of psychotic disorders compared to those with lower fitness.

The authors discussed a few potential mechanisms that may explain why higher cardiorespiratory fitness helps mental or neurocognitive disorders.

From a physiological perspective, improved brain blood flow, vascular function induces structural, cellular and molecular adaptations to enhance neuroplasticity which then support cognitive and emotional regulation.

Exercise and higher cardiorespiratory fitness has been shown to help maintain the size/ volume of the hippocampus. The role of the hippocampus is linked to emotion regulation, memory and cognitive resilience. Atrophy of the hippocampus has been consistently linked to mental and cognitive disorders.

Mental health disorders and neurodegeneration are definitely complex and multifactorial. Please note that the authors also did not just conclude that "exercise is the answer". They concluded that higher cardiorespiratory fitness appears to be associated with a lower risk of several mental and neurocognitive disorders and cardiorespiratory fitness may be a useful marker to sort out groups at risk.

This is also interesting to note. Because only 1 or 2 studies were available, the authors were not able to study them as a group. Those individual studies suggested that higher fitness may be associated with lower risk of bipolar related disorders, dissociative, obsessive-compulsive and stressor-related disorders, sleep apnea as well as anxiety and ADHD in children. Depression in girls also appeared lower with higher fitness.

If the fitness influencers do pick up on this topic, I hope they do not simplify it by making it as easy as doing "some exercise or sports". 

So taken at face value, higher cardiorespiratory fitness seems to lower risk across a wide range of psychiatric and neurocognitive disorders. Do note that genetic predisposition, chronic pain, social support, smoking and diet are definitely confounding factors.

The evidence does continue to add up showing that higher cardiorespiratory fitness helps with physical disease and premature death, but also with better mental health, lower dementia risk and other mental disorders. 

Reference

Diaz-Goni V, Lopez-Gil JF, Rodriguez-Gutierrez E et al (2026). Cardiorespiratory Fitness And Risk Of Mental Disorders And Dementia: A Systematic Review And Meta-Analysis. Nat Mental Health. DOI: 10.1038/s44220-026-00599-4

New Strength Training Guidelines From ACSM

Earlier this month the American College of Sports Medicine (ACSM) revised its strength training guidelines for the first time since 2009. Needless to say there are plenty of changes after 17 years.

Especially since strength training is still treated like a recipe by many healthcare professionals. Sets, reps, rest periods, percentage of 1RM (rep max).

This new stand came from a review of 137 systematic reviews and data from more than 30,000 participants making it the most comprehensive evidenced based review on strength (or resistance) training prescription.

Strength training definitely works. It improves strength, power, hypertrophy, muscular endurance, walking speed, balance and daily tasks.

Also an update that many forms of strength training can be effective. Not just lifting weights in a gym, but also elastic bands, circuit training, home based and speed based training.

To improve strength, the evidence suggests that one needs to strength train at least 2 times a week using heavier loads. Exercise through a meaningful range of motion with 2-3 sets doing the key lifts (exercise) at the start of the session.

For hypertrophy, what matters most is doing enough work. High volume weekly, especially more than 10 sets per muscle group each week. Eccentric overload would be most effective to enhance growth.

If you are training for power, moderate loads of 20 to 70 percent of 1RM max moved fast with low to moderate volume are suggested. Olympic style lifting and power focused training seems to be most effective.

Just as interesting to note is what did not consistently matter. Time of muscle under tension, training to failure, equipment type, set structure, periodization and blood flow restriction did not consistently show improvement across the studies reviewed.

Surprised? The best strength training program is definitely not the most complex or complicated one. It is one that you can do consistently and progress reasonably and sensibly over time. And to be able to do it long term.

No need to obsess over set structure, exercise selection, home gym or public. There is no perfect strength training program, the results come from what you can do regularly over time and not what looks best on paper. Adherence is what helps you progress.

Reference

Currier BS, D'Souza AC, Singh MAF et al (2026). American College Of Sports Medicine Position Stand. Resistance Training Prescription For Muscle Function, Hypertrophy, And Physical Performance In Healthy Adults: An Overview Of Reviews. Med Sci Sports Ex. 58(4): 851-872. DOI: 10.1249/MSS.0000000000003897.

You can read the whole article here.

Should Runners Get Running Gait Analysis?

My patient who's training for a marathon came to me this past week telling me she had a friend who had just gone for a paid running gait analysis. Stride length, cadence, gait symmetry were all filmed after checking for muscle imbalance, flexibility and joint alignment. She was tempted to go too.

I shared with my patient a really interesting article I read this past week (Cochrum et al, 2021). The study assessed if running coaches could visually assess a long distance runner's running economy. These 121 running coaches were coaching high school runners to runners at international level.

Running economy was measured in 5 trained recreational runners at about 12.8 km/ hour. The runners were filmed from the front, side and rear while running on a treadmill. There was a minimum VO2 difference of 2 mL.kg/ min between adjacent runners that the coaches visually assessed.

The coaches viewed each video and ranked the runners on a scale from 1 (most economical) to 5 (least economical). They also completed a demographic questionnaire and listed running style biomechanical observations they used in determining each ranking. 

There was also a statistical algorithm to determine the effect of coaching level, years of coaching, training experience, competition level, certification status and educational level on the ability to accurately rank running economy.

Get ready for this, NONE of the coaches ranked them all correctly. Only 6 percent (or 7 out of 121 coaches) managed to identify 3 correctly.

In our clinics, we sometimes blame running economy (due to cadence, stride length, running style, gait) as a cause of problems or injuries. From the research paper, it is surprisingly difficult to judge visually.

Perhaps most runners do not have a "wrong" running style or form. Running mechanics are definitely self organized. As one trains more regularly, their body would gradually find the path of least resistance. The running style would then suit their anatomy and training load after accounting for their injury history, and strength. 

Much research suggests that runners often become more economical simply by running regularly, without needing to consciously change their running style and technique (Van Hooren et al, 2024)

Does this mean most runners do not need running gait correction? Since biomechanical measures did not reliably predict injury suggesting that we cannot so easily "see a risky/ wrong running gait" and fix it. 

Most healthcare professionals may disagree (since it means they cannot charge their patients more) and I would encourage you to pause and take a step back. Do not assume your running style is the problem however fancy these "advance" running gait analyses may promise. Especially if you are not injured.

I am also not saying running gait analysis is useless. It can be helpful when a runner is already injured. Small adjustments like shortening stride length, width or increasing cadence can easily help runners with knee pain and help them return to running more comfortably while the underlying tissue settles.

So, if you are a healthy, non injured runner looking to run faster or even prevent injuries, it's better to work on your strength, recovery, consistency, training load and progression. Your running style may not need correction. Your body would have already figured that out, especially if you are a serious runner with more than 5 years of consistent running.

I may look at and discuss running gait in our clinic as part of my assessment, but it is usually not a immediate area of concern. Personally I do not like looking at running gait on a treadmill since it will be different compared to running outside. I would get my patients to run outside while watching them if I need to.

Unfortunately there are many other healthcare professionals who do not understand this or choose not to understand (so they can make more money), to keep up with this misconception.

References

Cochrum RG, Conners RT, Caputo JL eyt al (2021). Visual Classification Of Running Economy By Distance Running Coaches. Eur J Sp Sci. 21(8): 1111-1118. DOI: 10.1080/17461391.2020.1824020

Van Hooren B, Jukic I, Cox M et L (2025). The Relationship Between Running Biomechanics And Running Economy: A Systematic Review And Meta-Analysis Of Observational Studies. Soorts Med. 54(5): 1269-1316. DOI: 10.1007/s40279-024-01997-3

Running Associated With Good Intervertebral Discs Adaptations

Remember how I previously wrote that running helped eased my back pain after my compression fracture following my first bike accident. Well, this is not just coming from me (n=1) who has 2 compression fractures in my spine. A recently published article this past week (on 5th March 26) shows that running is associated with good intervertebral disc (IVD) adaptations (Samanna et al, 2026) too and thus may help those suffering from chronic low back pain.

The authors, in their randomized controlled trial, showed  how a 12 week run-walk program affected the spinal health of 40 adults with chronic low back pain.

The subjects either followed a digitally delivered progressive run-walk interval program of doing 3 run-walk days each week at 30 minutes a session or in a waitlist control group.

 

MRI were used to track changes in the health of the T11/12 to L5/S1 IVD relaxation times. This is a reliable way to assess IVD hydration and structural integrity. This was done at the start, 6th and end of the 12th week of the run-walk program. T2 values were tracked since it is influenced by IVD composition and water content, with higher values indicating higher hydration and better IVD health.

The results surprisingly showed that the subjects with more significant multi level IVD degeneration actually showed more favorable improvements in the IVD health after 12 weeks. Even more improvement than those with healthier discs.

This suggests that even IVD's that have already undergone degenerative changes still have the capacity to adapt and rehydrate when exposed to regular, dynamic movement. The "degenerated" IVD's with lower baseline hydration may also show greater potential for rehydration and measurable improvement since they are starting at a lower base.

A person's body mass index (BMI) did not significantly change how they responded to the program.

The study showed that a total running volume between 28.6 to 46.1 km over the 12 weeks led to best results for the IVD T2 changes. That is a manageable weekly average of 2.4 to 3.8 km.

Moderate running speeds between 10.5 km/h and 11.7 km/h was associated with better outcomes at the 12 week mark. 

Running on grass was also identified as a positive factor for improving disc health. Possibly because of a lower biomechanical load compared to running on concrete.

There was also some negative effects briefly seen at the 6 week mark with lower running speeds or those with mild degeneration, but they disappeared by week 12. This implies that the initial weeks may involve a temporary "adjustment" phase as the body adapts to new movements from a new exercise. Sticking with the program leads to long term benefits.

Do note that the sample size is fairly small and an improvement in T2 values may not necessarily reflect physiological or therapeutic improvement. The subject has to feel less back pain. I definitely have less back pain after running. Your discs definitely need the gentle loading from running.

Reference

 

Samanna CL, Neason C, Tagliaferri SD et al (2026). Running Is Associated With Intevertebral Disc Adaptations : A Pre-Planned Secondary Analysis Of The ASTEROID Randomised Controlled Trial. Eur Spine J. Epub 5 Mar. DOI: 10.1007/s00586-026-09759-7.

Inflammaging Across Human Populations

Aging is more than just getting gray hair and wrinkles. It is a gradual decline in how our cells in the human body function.  This can result from various metabolic, environmental and genetic factors. When our cells accumulate damage, important systemic processes in our body become dysregulated, and this leads to an increased rate of disease and mortality.

Inflammaging, a combination of inflammation and aging is when there is a chronic, low grade persistent  inflammation occurring in the body without infection or obvious injury. 

This is characterized by increased levels of inflammatory markers in the blood. The term was first coined by Claudio Franceschi to detect the systemic, hard to detect inflammation that creeps in with advancing age.

Inflammaging stems from an immune system that is malfunctioning, when there is overstimulation of our natural immune system and when damaged cells there do not die (cellular senescence). 

Increased tummy fat, genetic predisposition, accumulated cell damage and lifestyle factors like chronic stress and poor diet can contribute to it. It is a sterile and persistent process not triggered by acute infection. It accelerates aging and contributes to age-related diseases like Alzheimer's, diabetes, arthritis and cardiovascular diseases.

It then leads to functional decline, frailty and increased mortality.

A study published recently suggested that low grade chronic inflammation may be actually tied to environmental factors in industrialized countries. This suggests that inflammaging may not be equal in different parts of the world.

The researchers analyzed data from 4 different populations. Italy and Singapore (industrialized) and 2 non-industrialized (indigenous communities) in the Bolivian Amazon and Malaysia (Orang Asli). 

Orang Asli

They found that inflammation levels increased with age in industrialized societies while this was absent in the non-industrialized societies studied. In the non-industrialized societies, inflammation appeared mostly linked to short term infections rather than chronic age-related diseases.

Their findings suggest that the persistent inflammation seen in wealthier nations may be more influenced by lifestyle and environmental factors such as pollution, diet, levels of physical activity rather than aging itself. 

This shows the need to consider both environmental and cultural contexts while studying the causes of aging. 

The human species have gone from increasing lifespan over the past 150 years to extending lifespan and living well. 

Before falling from grace recently because of ties with Jeffrey Epstein, Peter Attia and American entrepreneur Brian Johnson have been at the forefront of the "living forever" (or longevity) movement. Johnson has even organized the Rejuvenation Olympics to get participants to find ways including exercise and dietary supplements to slow biological aging. 

Johnson's tactics have been labeled extreme in cost and nature especially when he gets regular injections of blood from his teenage son. Perhaps he needs to go live in indigenous communities for a while to help him in his quest.

Reference

Franck M, Tanner KT, Tennyson RL et al (2025). Nonuniversality Of Inflammaging Across Human Populations. Nat Aging.5 : 1471-1480. DOI: 10.1038/s43587-025-00888-0

Still Think It's The Thigh Muscles?

I have seen many patients who have had an anterior cruciate ligament (ACL) tear over the years.  Some patients chose not to go under the knife but most had reconstruction done. ALL of them were taught to focus their strengthening on their quadriceps (or thigh) muscles.

So not surprising that a recently published study by Alzobi et al (2026) found that patients who did not opt for surgery exhibited progressive hamstring muscle atrophy.

A total of 1,207 thighs were examined. There were 92 with ACL tears and the other 1,115 acted as controls. The average age of the subject group was 61± 9 years.

Over 4 years, the ACL deficit thighs were smaller by an average of 28.18 mm, all due to progressive hamstring atrophy. The differences ranged from 13.92 to 42.43 mm smaller. The sartorius muscle also atrophied by an average of 3.02 mm.

There were no significant differences in the quadriceps or adductor cross sectional area. hamstring force was decreased significantly whereas quadriceps force showed no significant change.

The researchers concluded that muscle deterioration occurred in the posterior thigh muscles (hamstrings) with minimal changes in the front thigh muscles (quadriceps) over time. And for ACL deficient knees, it is really important to target long term rehabilitation strategies focusing on hamstring preservation. 

We already know that one of the reasons women sustained ACL tears is that their hamstrings were significantly weaker than their quadriceps muscle strength.

If you have been reading our previous blog articles, you already know that the quadriceps (thigh muscles) and gastrocnemius (calf muscles) increases load on the ACL due to anterior shearing forces at the tibia (shin bone). This is especially so when the knee is straightened (Maniar et al, 2022).

The hamstrings and soleus (deeper calf muscles) help to unload the ACL by generating posterior tibial shearing forces (Maniar et al, 2022).

So for those of you who have torn your ACL, whether or not you choose to go for surgery, make sure you focus on your hamstrings and soleus muscles instead.

References

Alzobi O, Mohajer B, Fleuriscar J et al (2026). Thigh Muscle Changes In The ACL-Deficient Knee: A 4-Year Lonitudinal MRI Study of 1,207 Patients. JBJS Am. 108(3): 219-226. DOI: 10.2106/JBJS.25.0064

Maniar N, Cole MH, Bryant AL et al (2022). Muscle Force Contributions To Anterior Cruciate Ligament Loading Sports Med. DOI: 10.1007/s40279-022-016743

Carbon Plated Running Shoes Improve Running Economy

Picture from Runrepeat.com

Remember my post on whether super running shoes work or whether it was just a placebo, especially for recreational runners?  Well, for serious runners they definitely make one run faster. 

In theory, the super shoes reduces your energy cost when you run, making runners more efficient at the same running speed.

How do they actually make you run faster? In my past versus present post, I highlighted how super highly stacked midsoles, super responsive PEBA foam, and uppers are optimized biomechanically. In addition, the carbon plates offer runners with energy return on every stride. The propulsion and fit designed to minimize fatigue over the whole marathon distance, almost like pushing off, off a trampoline when you run.

However, what if one ran in carbon plated running shoes versus shoes that did not have a carbon plate? That was what a new systematic review investigated, how much lower the energy cost is when you compare running in carbon plated versus non carbon plated shoes and how big the effect was.

14 studies pooled by researchers to compare carbon plated versus non carbon plated shoes when running (Kobayashi et al, 2026). Each runner in all the studies ran in both types of shoes to minimize 'between-runner" variability.

The results showed that the carbon plated shoes significantly lowered metabolic cost (or energy cost) for all the variables measured. Running economy, oxygen consumption and energetic cost of transport (ECOT)  all favoured the carbon plated running shoes.

Here's what the researchers summarized that was interesting. The carbon plated shoes lowered metabolic demand during running by 2 to 3 percent on average. This means that the total amount of energy and oxygen required by the body to sustain cardiovascular function, muscle demands and heat regulation while running was less in the carbon plated shoes.

This matches what runners "feel" in super shoes. Not a night and day transformation but definitely a sufficient edge, more so when pace increases and race distances get longer. (Recap: runners were only running 6 minutes at 10 km/h pace in the super shoes or super placebo post).

So if you are still deciding on buying carbon plated super shoes for your next attempt to beat your 10km/ 21km/ marathon, (or insert your distance) personal best, the scientific answer is a definite yes. Especially if you are not a beginner and can afford them.

Reference

Kobayashi EN, Toledo RRF, de Almeida MO et al (2026). Metabolic Effects Of Carbon-Plated Running Shoes: A Systematic Review And Meta-Analysis. Front Sports Act Living. 9(7): 1710224. DOI: 10.3389/fspor.2025.1710224