Monday, November 23, 2015
I have always been a poor sleeper. Even when I was training very hard. In fact when I pushed myself too hard at training, I usually found it harder to fall asleep. And I could never sleep in. My internal body clock is set such that I could never sleep past 7 am.
Turns out not being able to sleep in may not be such a bad thing after all.
A group of researchers studied 447 men and women between the ages of 34 to 54. They wore devices that tracked movement and also monitored them when they slept and woke.
Nearly 85 percent of the group went to sleep and woke later on their off days compared to during their work days.
The researchers found that the greater the mismatch in sleep timing between their week days and week ends the higher the metabolic risk.
Sleeping late on off days (week ends) was linked to lower HDL (or good) cholesterol, higher triglycerides, higher insulin resistance and a higher body mass index. This is true even after adjusting for physical activity, caloric intake, alcohol intake and other factors.
The researchers are not sure if this is similar in the long term as the subjects were only studied for seven days. Several other studies have shown that there is an association between shift work and in increased risk for heart disease and diabetes, similar to what this study has shown.
Don't stay up too late on your off days.
Wong PM, Hasler BP et al (2015). Social Jetlag, Chrontype And Cardiometabolic Risk. J of Clin Endo and Metabolim. DOI: http://dx.doi.org/10.1210/jc.2015-2923.
Sunday, November 15, 2015
|Chromosome by Hey Paul Studios from Flickr|
The researchers found evidence from family and genetic studies that DNA sequence variants (together with non-genetic factors) can increase your risk for tendon and ligament injuries. This is for both exercise-associated and occupational-associated acute and chronic injuries to tendons and ligaments.
Although research at this stage is still preliminary, there have been specific gene variants found (COL5A1 gene) that are less likely (58 percent less) to cause Achilles tendinopathy (degenerative change in the tendon).
A different gene (COL1A1) is associated with ACL (anterior cruciate ligament) and Achilles tendon ruptures (September et al, 2009).
In fact, several other genes have been associated with injuries ranging from carpal tunnel to tennis elbow.
The common link among these genes is that they affect collagen fibrils structure. Collagen fibrils are the basic structural building block for tendons, ligaments and other connective tissue including fascia. In simple terms, some Achilles tendons are built better than others.
So what do you do with this information then? Athletes and coaches beware, especially when there are now many genetic tests marketed for self testing promising to reveal potential injury susceptibilities.
The researchers reported that such tests should be requested by an appropriately qualified healthcare professional since results need to be interpreted together with certain clinical indicators and other lifestyle factors.
Personally I'm fairly sceptical about such over the counter/ online genetic tests that you can purchase to do a self test on whether you're more prone to injury.
Will knowing that really change your training habits? As a previously compulsive competitive athlete, I trained as hard as I could handle and more without getting injured. Knowing I'm say, 10-20 percent more likely to get a tendon injury will not alter my day to day training. On the contrary, because I've been training hard for so long (previously), I know what injuries I'm prone to because I've already had them previously.
Hmmm, maybe from now I'll ask my patients whether they have a family history of tendon or ligament injuries instead. (Standard practice for Physiotherapists is asking patients if they have any family history of hypertension, heart diseases and cancer etc).
Collins M, September AV and Posthumus M (2015). Biological Variation In Musculoskeletal Injuries: Current Knowledge, Future Research And Practical Limitations. BJSM. DOI: 10.1136/bjsports-2015-095180.
September AV, Cook J et al (2009). Variants Within The COL5A1 Gene Are Associated With Achilles Tendinopathy In Two Populations. BJSM. 43: 357-365. DOI: 10.1136/bjsm.2008.048793.
Thursday, November 5, 2015
|Straits Times (051115)|
We wish him well for his recovery.
It's in the Straits Times today on page B10.
Sunday, November 1, 2015
|Picture by Cindy Funk from Flickr|
I told both of them what I knew was that under laboratory testing conditions, more pounding translates into shorter lifespans for artificial joints. That means when you load your joint more (after hip replacement surgery) during running, the artificial joint will wear out more rapidly than someone who participates in lower impact activities such as cycling or swimming.
Adverse effects could mean dislocations, fractures, loosening of the prosthesis and scraping off and scattering within the body of metal fragments.
In a 2014 study, researchers investigated 23 adults who returned or started running after hip replacement surgery reported few problems five years after their surgery. There was very little evidence that their subjects experienced the above mentioned adverse effects.
Theirs was quite a small group of subjects and the follow up period was relatively short too.
In another larger study, 804 hips from 608 patients were investigated. Among the subjects who ran (an average of four times a week covering 3.6 km), none of the subjects had any loosening, abnormal implant migration or excessive wear during the five year follow up as well.
I suggested to my patient (who had the hip replacement done) that she shouldn't rush back to running after surgery. She needs to regain full range of motion in the hip and get the muscles around the joint strong first before attempting to run. Of course I suggested deep water running/ aqua based rehabilitation first.
Abe H, Sakai T et al (2014). Jogging After Total Hip Arthroplasty. Am J Sp Med. 42(1): 131-137. DOI: 10.1177/0363546513506866.
Meira EP and Zeni J Jr (2014). Sports participation Following Total Hip Arthoplasty. Int J Sports Phys Ther. 996): 839-850.
Sunday, October 25, 2015
|Picture by Irving Henson from The Pit|
Maybe you didn't exercise hard enough? That was the first thing that came to mind when they asked for my thoughts on that matter. Granted, I know not everyone responds the same way to a certain exercise program. Turns out I may be right when I recently came across the following article.
Researchers studied 121 sedentary and obese adults who exercised five times a week over a duration of 24 weeks.
The subjects were split into three groups. A low intensity, low duration group who did moderate walking (31.2 minutes of exercise at 50 percent VO2 max). The second group exercised at low intensity but longer duration (57.9 minutes of exercise at 50 percent VO2 max). The final group did a higher intensity, longer duration of brisk walking (39.7 minutes at 75 percent VO2 max).
After four weeks there were "non-responders" across all three groups. Non responders were those whose fitness levels did not improve.
The number of "non-responders" decreased as the weeks passed although they remained in the low intensity groups. There was however, no "non'-responders" in the high intensity group, meaning everyone in that group got fitter.
The researchers suggested that there will not be any "non-responders" as long as they exercised hard enough for long enough.
Hard enough in this study basically involved brisk walking, meaning you may need to do more if you're younger and fitter.
Ross R, de Lannoy L and Stotz PJ (2015). Separate Effects Of Intensity And Amount Of Exercise On Interindividual Cardiorespiratory Fitness Response. Mayo Clinic Proceedings. pii: S0025-6196(15)00640-0. DOI: 10.1016/j.mayocp.2015.07.024.
|Walk this way! (Picture by Irving Henson from The Pit|
Friday, October 16, 2015
|How many of you recognize this shoe? Reebok ERS 5000- from 1988|
It seems that many shoe companies are joining the energy return movement again. Why did I say again?
Well, looking at the picture above, how many of you will know what I'm talking about if I mention "ERS"? To be specific, the Reebok ERS or energy return system technology Reebok came up with in 1988 to compete with the Nike Air technology. That was way back in 1988!
Let me sidetrack a little. The ERS comprises of a series of cylinders made from Dupont Hytrel placed in the midsole of the shoe to act as springs. This was meant to help propel the runner forward after foot strike or so Reebok claims. (Note - ERS was phased out when Reebok invented Hexalite their next technology). Come talk to me if you wanna discuss shoe technology from the 80's and 90's.
|The Adidas Boost|
When a running shoe cushions well, it also lowers the responsive response of that shoe (since it has to absorb the force). A responsive shoe means firmness in that shoe and that firmness allows you to transfer the force from your stride into running faster.
And cushioning and responsiveness are mutually exclusive. Either you have a shoe that is soft and cushions your landing by dissipating that energy or a shoe that allows your to put your energy directly into propulsion.
These new energy return shoes try to combine the two properties. They absorb more than the previous traditional foam used in running shoes and then store that energy that was absorbed to return the foam to original shape quickly producing a responsive feel as they push back on the bottom of your foot during push off.
Despite what the ads say, no material can actually produce energy that can propel your next running step. No foam can actually do that. The basic law of physics states that no system creates or destroys energy. Energy can only be transformed. If anything, what energy that is returned tends to be generated by your own stride in the first place.
Even if the foam did bounce back harder than it was compressed, it is unlikely it can propel you in any meaningful way. This is because running involves forces generated by your muscles, joints, tendons and bones along with gravity and friction. In order to get that "energy return", the energy has to be returned at the right time, frequency and right location (Nigg, 2010). It just doesn't happen so easily.
The running shoe industry has yet to get all these variables working together, regardless whether the rebound is from foam, tubes, springs or mechanical trampolines used by Newton, Spira or any other brand currently.
Moreover, the current energy return foam is fairly heavy. Weight has a large impact on running shoes. Previous studies show that for every 100 grams (or 3.5 ounces) added to your foot, energy cost is increased by one percent. This is also why you want to use racing flats when you race as a lighter shoe allows your foot to turnover faster and thus leading to faster race times.
If you have tried some of these newer "energy return" shoes though, you just might be sold on them. They actually feel fantastic when you first try them on. One of my patients who's tried it said his feet felt like a million dollars. But like I always say, it's the legs (and running technique) that makes you fast not the shoes.
Previous studies have shown that your own muscles and tendons and a good running technique will reduce overall impact forces better than the midsole of your running shoe can. What is important in the cushioning of the shoe is spreading the load across your foot. This may explain why those who switched to minimalist/ barefoot running type shoes had no more knee or hip pain but ended up with stress fractures on their metatarsals (or foot bones) instead. This of course lead to a huge outcry against such minimalist/ barefoot running type shoes.
So, now you know that getting energy return or propulsion is not so straight forward and not something you should expect from a shoe. Not yet anyway.
Liberman DE, Venkadesan et al (2010). Foot Strike Patterns And Collision Forces In Habitually Barefoot Versus Shod Runners. Nature. Jan 463(7280): 531-535.
Nigg BM (2010). Biomechanics Of Sports Shoes. Calgary, Alta. : University of Calgary, c2010.
Sunday, October 11, 2015
|Now that's a strong calf|
The article looked at a whole range of variables across a wide range of runners. The runners studied ranged from age 23 to 59 years old. The runners were filmed running at their normal pace on a treadmill with a high speed video camera.
The older runners in the study maintained the same stride frequency as the younger runners (about 83 strides/ minute). The one glaring difference was that they had a much shorter stride length, which the authors felt reduced their running speed.
Stride length and running speed decreased by about 20 percent from age 20 to 59. Ankle power also dropped by almost 48 percent during the same time frame leading the researchers to conclude that runners could probably maintain their running speed by increasing their calf muscle strength and power.
The authors suggested that strengthening the gastrocnemius and soleus muscles (which make up the calf muscles) will benefit runners. They suggested using a combination of slow reps but with heavy weight workouts and faster but using lower weight power workouts to strengthen the calf and to stave off the slowdown.
The authors were also impressed that the runners managed to maintain their weight through the decades and suggested that long term running could be an effective way to maintain weight without medication.
Personally, I feel that if you ran with good technique, you won't need to strengthen your calves. Look at the Kenyans and the Ethiopians that win all the big races all over the world, have they got big strong calves?
DeVita P, Fellin RE et al (2015). The Relationships Between Age And Running Biomechanics. Med Sci Sports Ex. Epub. DOI: 10.1249/MSS.0000000000000744.
|Here's another look - thanks to Vinny for the pictures|