New Study Does Not Recommend Standing Desks

Picture from CMD

I have written previously on the ill effects of sitting and prolonged sitting. This has also led to the phrase that "sitting is the new smoking". Which subsequently led to standing desks as a 'trendy' option to offer a way to reduce sitting time.

Previously, some of my patients have also asked me to write a memo for them so they can get  their company to pay for a standing desk at work, while other patients have simply asked for my opinion.

My take on standing desks then? I've seen many of my patients go straight from sitting to a standing desk get different problems. Being unaccustomed on their feet all day long posed new risks. It can inhibit proper circulation and add additional pressure to your legs, hips and lower back. Sort of like jumping from the frying pan into the fire if you ask me.

My suggestions for these patients was not to switch to a standing desk for the full work day, especially if they have been sitting all day immediately. To make sure they gradually phase it in.

Like previous ergonomic chairs, desks etc, there hasn't been much evidence supporting the benefits of standing desks. The earlier limited studies did not comprehensively assess long term health consequences.

In a newly published study this month (Ahmadi et al, 2024), 83, 013 participants wore devices for up to 7 years to track their sitting, standing and physical activities. This was more accurate and objective than self reporting by subjects. The researchers found that sitting for more than 10 hours a day was associated with a higher risk of heart disease and stroke.

The researchers also found that standing more did not mitigate this risk of stroke and heart disease. In fact standing for extended periods was linked to a increased risk of circulatory problems. This suggested that simply changing from stationary sitting to standing will not solve the problem since our bodies respond better to movement rather than staying in static positions. Remember motion is lotion.

Workplace interventions that promote movement found that office workers who reduce sitting time by adding light walking and standing had improvements in blood sugar levels.

So, walk to your colleague to talk to them instead of calling or emailing, take the stairs often instead of elevators, walking to the pantry etc all contribute. Better still if you can do 10 bodyweight squats every 45 minutes. All these can make a significant difference.

Reference

Ahmadi MN, Coenen P, Straker L et al (2024). Device-measured Stationary Behaviour And Cardiovascular And Orthostatic Circulatory Disease Incidence.  Int J Epidemiol. 53(60: dyae136. DOI: 10.1093/ije/dyae136

*Note that the study's large population use and the use of devices to measure objective data strengthen the findings. However, observational studies may not totally establish cause and effect. Also since the average age of the subjects was about 61 years, it may not totally apply to younger popuplations.

Single Leg Versus Double Leg Training

L leg bigger

We see many cases where patients have one limb bigger than the other in our clinics. There is an imbalance or deficit between limbs e.g. healthy versus injured, left versus right or dominant versus non dominant. This is also known as interlimb asymmetry in research. 

Strength, power, reactive strength have been shown to be affected when there were interlimb asymetries, especially in sporting performances. I have seen differences of 10-15 percent in deficits for patients even 5 years after they had surgery. Hence, I often suggest that patients work on single limb exercises to reduce this deficit/ asymmetry.

Single leg and double leg strength exercises, plyometrics, balance and even core training have been investigated in a wide variety of athletic populations to understand the effects of interlimb asymmetry. The following systematic analysis was to examine if training interventions are effective in reducing interlimb asymmetries and which types of interventions were more effective in the athletic population.

The single leg counter movement jump (SLCMJ), single leg broad jump (SLBJ), single leg lateral jump (SLLJ) and change of direction (COD) speed were the most commonly used test to check for sprint performance, jump height and COD speed.

Ready for the results? The review suggested that all training interventions have a small to moderate effects on the reduction of asymetry in SLBJ, SLCMJ and COD speed from pre to post training, although no statistically significant differences were reported. This was found in the intervention groups versus the control groups.      

The researchers suggested both unilateral and bilateral training should be considered to decrease interlimb asymmetries. If you're an athlete and have any limb asymmetries and no pain, then definitely do both single and double leg exercises to reduce the asymmetry. 

Please note that the above study was done on athletic populations. I will definitely avoid single leg exercises in the recently injured/ immediate post surgery patients and get them to do bilateral leg exercises first.

What about patients who are not loading equally a year (or longer) after a knee replacement or ACL reconstruction? I always see patients who tend to compensate too much with the non injured/ painful leg. By doing single leg exercises (pictured above), I can make their weaker side work harder.

Reference

Bettariga F,Turner A, Maloney S et al (2021). The Effects Of Training Interventions On Interlimb Asymmetries: A Systematic Review With Meta-Analysis. Strength Cond J. DOI: 10.1519/SSC.0000000000000701

Your Workout Today May Trigger A bright Idea Next Week

Picture from Triana et al (2024)

What if I told you your exercise session today can trigger a bright idea next week? That's exactly what a recent study by Finnish researchers found. They tracked a person's brain and behavioural activity for 5 months using brain scans and data from smart phones and wearable devices. 

This research (Trinan et al, 2024) was unusual since few brain scan studies involve such detailed monitoring over months. Using wearable technology in this study was crucial, especially since brain scans (while being useful) only shows the subject lying still for 30 minutes. 

2 distinct patterns were identified by the researchers. A short term wave that lasted under 7 days and a long term wave by up to 15 days. The short term wave reflects rapid adaptations like how focus is affected by poor sleep although it recovers quickly. The long term wave suggests more gradual, lasting effects, especially in areas tied to our attention and memory.

The study found that our brains do not respond to our activities of daily living in immediate, isolated bursts. Our brain activity evolves in response to our sleep patterns, physical activity, mood, and respiration rate over many days. This means that your exercise session or a restless night from the previous week can still affect your brain. Hence your memory, cognition and attention can be affected well into the next week.

It is a great study linking brain activity with environmental and physiological data as tracking our brain changes in real time can help detect mental health and neurological disorders early. This allows for earlier interventions and better outcomes.

Even though this study was not focused exclusively on exercise, the results showed that we definitely need a consistent exercise routine and maintain good sleep habits for our overall well being. I find myself particularly sensitive to these as I age. 

Reference

Triana AM, Salmi J, Hayward NME et al (2024). Longitudinal Single-subject Neuroimaging Study Reveals Effects Of Daily Environmental, Physiological, And Lifestyle Factors On Functional Brain Connectivity. Plos Bio. DOI: 10.1371/journal.pbio.3002797

Something You Do Not Know About Muscles

Picture from Burke et al, 2024

This is a very interesting finding about muscles. The muscles we use while exercising can actually communicate with our adipose (fat) stores in our body.

This study was done with 32 human subjects. A single bout of resistance exercise (or strength training) releases muscle specific microRNA-1 (miR-1) from muscles that are then transported to abdominal fat tissue via extracellular vesicles or EVs to stimulate lipolysis. Lipolysis is the breakdown of fats and other lipids to release fatty acids. This means you can use fats for energy, sparing your carbohydrate and protein.

I know what some of you reading must be thinking. Is spot reduction possible? Spot reduction means selective loss of body fat in regions involved in the exercise. Meaning can we isolate the fat in the abdomen (for men) by doing cruches or sit-ups?  Or doing lunges for the buttock and thighs (for women) and get rid of the fat there first? 

Well, sorry to disappoint you. In this study, the exercises were mainly done in the lower body- squats, leg press, leg extension and also lat pulldown (for the upper body). 3 sets of 8 reps at 80 percent of 1 rep max on the aboved mentioned exercises were performed. A fourth set to failure was performed straight after.

The lipolysis or fat breakdown in the adipose tissue was in a non specific area - the abdominal region. This was confirmed by the EV's found there.

Perhaps this is an interesting consideration suggesting that our muscles can function like a secretory organ. Like a giant endocrine organ in the body, more than we realize anyway. (Note : thoughts are my own, not from the study).

We are definitely only scratching the surface of understanding how exercise has so many other unknown benefits.

The women in the study did not have as strong an effect compared to the men in the study. Also note that is is a relatively small study with only 32 subjects.

If you are not already doing any strength training, you should. Not only it can increase your bone density, helps with insulin sensitivity, promote better sleep etc, it can also break down your stored fat.

Reference

Burke BI, Ismaeel A, Long DE et al (2024). Extracellular Vesicle Transfer Of miR-1 To Adipose Tissue Modifys Lipolythic Pathways Following Resistance Exercise. JCI Insight. DOI: 10.1172/jci.insight.182589