Sunday, June 29, 2014

Can Running (And Other Endurance Sports) Lead To Worse Dental Health?

Picture by Jason Lee from Flickr
While out with my son earlier today, I met a patient asking why I hadn't written recently. I told her that since Luis Suarez and his teeth attracted attention for all the wrong reasons recently at the World Cup, I'll be writing a post on teeth as well. She then asked me what does running have to do with teeth?

Well here you go Audrey, a post on how running (or endurance exercise) can affect your teeth.

A group of German researchers studied a group of triathletes and non athletes and found that the triathletes had significantly higher rates of tooth erosion. What's more, among the athletes, those who trained harder had more cavities than those who trained less.

The researchers found that 46% of the athletes consumed sports drinks while training, while 51% drank water. 74% used gels or bars during training. Both groups revealed no significant difference in cavities, but those who trained the most amongst the triathletes had the most cavities. There was also a highly significant difference in the triathlete group for tooth erosion.

Like me, you must be starting to scratch your head and wonder why. Well, due to the triathletes high carbohydrate consumption of which includes gels, bars and sports drinks during training, their mouth's pH levels are below 5.5 (and  hence acidic), leading to dental erosion and cavities. In addition, during hard training, the athletes breathe through their mouth, making the mouth dry and produces less saliva (more acidic), which normally protects the teeth.

Note that both groups had similar saliva profile at rest. Only when the athletes begin exercising then they had less saliva. Degree of acidity increased with the length of time spent exercising.

The researchers concluded that endurance training has a detrimental effect on oral health.

This view has been raised before by Needleman and colleagues who found poor dental and even overall health in many Olympic athletes at the London 2012 Olympics (Needleman et al, 2013). Prof Tim Noakes suggested that this may happen due to their high carbohydrate diet and the frequent ingestion of sports drinks.

So make sure you brush your teeth following your bike or run session, especially if you've consumed gels, bars or sports drinks during or after your run.


Needleman I, Ashley P et al (2013). Oral Health And Impact On Performance Of Athletes Participating On The London 2012 Olympic Games: A Cross-sectional Study. BJSM. 47:1054-1136.doi: 10.1136/bjsports-2013-092891.

Frese C, Frese F et al (2014). Effect Of Endurance training On Dental Erosion, Caries, And Saliva. Scan J Med Sci Sports. doi: 10.1111/sms.12266.

Always clean your teeth after you run
Picture by doc18 from Flickr

Friday, June 20, 2014

Shin Splints Most Common In New Runners

Picture by Anne Sophie from Flickr
Latest published  research indicates that shin pain is the most common complaint among new runners. Shin splints or stress fractures is also our most popular article in this blog with over 200 comments and counting.

The researchers studied 933 new runners for a year to see how many were injured, what injuries they had and how long it took before they resumed running. They were considered new runners if they haven't run more than 10 kilometres the previous year. The runners were considered injured if they had running induced pain in their legs or lower back that prevented them from training (distance, duration, pace or frequency) for at least a week.

254 runners were injured during their first year of running. 15% of this injured runners had medial tibial stress syndrome (or shin splints), 10% had knee pain, 7% injured their Achilles tendons while 5% hurt their plantar fascia or soleus (deep calf muscle).

Stress fractures were relatively rare, probably because the new runners' mileage in their first year were not high enough. 75% of the injuries happened during the runner's first 201 kilometres.

Time to heal varied widely amongst the injured runners.Those who hurt their calf resumed training after 30 to 40 days, while those with shin pain took an average of 72 days to fully recover. The worst were those who had plantar fasciitis, it took an average of 159 days to recover.

Majority of the 254 injured runners recovered fully (220) by the end of the year long study. Only 34 remained injured.

The researchers concluded that their findings emphasized the importance of the need for new runners to be mindful of shin splints as it is most common injury in their study. Even among recreational and elite runners, shin splints was the most common injury with an incidence of 13-20% (Lopes et al 2012).

Wanna run pain free? Have a read here.


Lopes AD, Hespanhol Junior LC et al (2012). What Are The Main Running-related Musculoskeletal Injuries? A Systematic Review. Sports Med 42: 891-905.

Nielsen RO et al (2014). A Prosepective Study On Time To Recovery In 254 Injured Novice Runners. PLOS One. DOI: 10.1371/journal.pone.099877.

Even Kobe has shin pain. (Picture from Flickr)

Friday, June 13, 2014

A Hard Warm Up Helps You Run Faster

Weight vest from Flickr by Dennis S Hurd
Wanna run faster in your next race? Turns out a hard warm up can help you run faster before your race.

If you've ever been to a track meet and seen the runners warm up, you'll probably see them jog/run a fair bit, do some running drills, short sprints or strides (depending on their event) and other fairly vigorous activities as part of their warm up. You'll probably see the same prior to hard track/ interval sessions of some runners if you run at your local track. Usually the shorter the race, the more intensive the warm up.

Now there's research backing this up. Researchers studied a group of runners who went through their warm up and a race simulation thereafter on 2 occasions.  Before each race simulation, the runners (as part of their warm up) did 10 mins of easy jogging, 5 mins at a brisk (but not all out pace), six 10-seconds of striding (or accelerations at their mile race pace or faster). The runners rested 10 mins and did a series of jumps, another submaximal 5 min run and then a treadmill test at peak running speed.

That's some weight vest! (Picture by Ving Henson from The Pit)
The only difference was the runners wore a weighted vest while doing their 10-second striding. The runners after warming up with the weight vest had results significantly better. Their running economy was 6% better on the post striding 5 min run, peak running speed was 2.9% faster! (Running economy measures your running efficiency. You can run faster at the same effort if your running economy improves as that pace will feel easier, hence elite runners often use intervals to improve their running economy).

The researchers think that increased "leg stiffness" noted in the post striding jumps primed the legs and improved running economy in the runners, leading to faster times. I suppose an exercise scientist would say that running with the weight vest causes neuromuscular training adaptations (which means your brain is also being trained)  which makes the runners' legs stiffer so their running economy improves.

If you said "Jump", I'd say "How high?" Picture from The Pit 
A similar scenario may be felt for those of you who run intervals. You will probably notice that during your first 2-3 reps (of say a 10 x 1 km interval session) will feel more difficult than the next few reps as your body acclimatizes.

Now before you go and order that weight vest, do keep in mind that this work best for track middle and long distances and for road races up to 10 km. You should also try this in your interval training sessions and before low key races to see how it works for you before trying it prior to an important race.


Barnes KR, Hopkins WG et al (2013). Warm-up With A Weighted Vest Improves Running Performance Via Leg Stiffness And Running Economy. J Sci and Med in Sport. DOI: 10.1016/j.jsams.2013.12.005.

Sunday, June 8, 2014

Is Carbohydrate Loading Still Relevant For Endurance Sports?

Picture by Weena from Flickr
Runners accept that carbo loading to be a norm prior to a race. Exercise physiologists have long told us that our muscles primarily use muscle glycogen (what the carbohydrate we eat turns into) during high intensity exercise. Hence we are advised to eat large amounts of carbohydrate before and during exercise.

However, 3 famous exercise scientists have come forward and suggested this is not totally logical. Since most if not all elite (and recreational) athletes spend most of their time training at submaximal levels (and not at high intensities) is it necessary to always eat a high carbohydrate diet?

The authors suggest that there is a lack of evidence surrounding low carb diets and its relationship to performance in the endurance exercise. Out of only 11 published studies done previously, 9 of them actually suggests that the subjects perform better or at least the same on a low carb diet compared to a high carb diet.

As a matter of fact only one study out of the 11 used subjects that were used to a low carb diet. Why is this important? Well just like a runner who have just changed shoes from a "regular cushioned" pair to a thinner soled pair will need time to adapt, a low carb eater will need time to adapt if he/ she has been used to a typical high carb diet (used by most runners).

As humans store limited amounts muscle glycogen in the body, this glycogen is mostly depleted after 20 miles of running. Hence runners often "hit the wall" after 20 miles into the marathon. Our bodies however store large amounts of fat in the body, if we can utilize the fat stores we have, we would be able to run two marathons back to back.

One of the authors (Phinney) in the current paper published a previous study in which cyclists after being on a low carb diet for three weeks used significantly more fat than they had on a typical high carb diet. Moreover, they also showed a four fold reduction in the use of muscle glycogen. This is remarkable as it was thought to very difficult (or even impossible) to produce energy purely from utilizing body fat (and not using muscle glycogen) at such high intensities of exercise.

Based on the Paleo outlook, the authors suggested that the subjects were able to have instant access to their fat reserves at all times since they live and train on low blood sugar levels (based on their low carb diet). This metabolism is similar to our ancestors in the prehistoric (or caveman era) where they were predatory hunters.

Since there is much variation among athletes, there are many unanswered questions regarding low carb diets especially since there are so many more studies done on high carb diets.

We await more research on the effectiveness on low carb diets since there may be long term health consequences of regularly eating a high carbohydrate diet since there are increasing numbers of recreational athletes who are insulin resistant (IR 4-6) and those eating too much refined sugar from high carbohydrate diets may be at risk of developing Type II Diabetes Mellitus.


Nokes T, Volek JS and Phinney SD. (2014). Low-carbohydrate Diets For Athletes: What Evidence? BJSM. doi: 10. 1136/bjsports-2014-093824.

Phinney SD et al (1983). The Human Metabolic Response To Chronic Ketosis Without Caloric Restriction: Preservation Of Submaximal exercise Capability With Reduced Carbohydrate Oxidation. Metabolism. Aug 32(8): 768-776.

Low carb diet
Picture from Flickr