Waterloo Chiropractor, Physiotherapist and Registered Dietitian

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Sports Science

keto 1

Welcome to part 2 of the my exploration of very low carb diets for endurance athletes.  My last article provided the basis for understanding this article as it explored how and when our body choses to use fat vs. carbs.  Check it out here.

In this article, I will now explore (1) do low carb diets actually enhance fat metabolism and (2) does that actually makes us faster.

Does VLCD increase fat burning capacity?

Short answer, yes, the body is forced to increase fat use to support the energy needs during exercise. Research clearly shows that after adapting to a keto diet for as little as 3 weeks results in significantly elevated rates of fat oxidation (0.6g/min to 1.5g/min) during exercise. Fat oxidation at moderate intensities (65% VO2max) in elite ultra-endurance athletes on a keto diet contributed 88% of the fuel for exercise verses 56% in athletes consuming high carbohydrate diets. Now, if we remember what we discussed in the last article, we learned that as we increase intensity we increase the amount of carbohydrates burned. This begs the question “will those high fat oxidation rates continue at intense ecercise (80% VO2max)?”. Another study investigated the fuel usage of elite race walkers at 80% VO2max, and they too found that fat oxidation was elevated to the same levels as previous research (1.5g/min).

low carb

Research Outcomes of VLCD and Performance:

The more important question in my mind (and likely yours as well) is “well that is fine and dandy- my body will burn more fat, but what will happen to my performance?!”. We will review some key research studies that have looked at fat adaption diets (high fat diets for 3-7days), keto diets and their effect on performance. The majority of high fat diet adaptation and keto diets find that performance decreased and a handful found they had no-statistically significant effect. Only two articles find a performance benefit.

Keto, Training and Performance

Louise Burke et al. (2017) conducted a large study investigating the effects of a keto diet, chronically high carbohydrate diet or periodised carbohydrate diet on race performance of elite race walkers after a 3 week intervention and training camp. Athletes on the keto diet perceived the training to be significantly more difficult and experienced an inability to complete the exercise training sessions planned. This is a very important point because if an athlete cannot train as hard as they could they won’t see much improvement in their sport.

After the 3 weeks of intense training, the keto group had higher fat oxidation compared to the two high carbohydrate groups. All groups had significant increases in their maximal oxygen uptake (VO2max) as a result of the training. As we discussed in the previous article, burning fat is less efficient and this study clearly demonstrated that at all competition race speeds there was significantly more oxygen used in the keto group and there was no change in the fraction of VO2max at various speeds. The high carbohydrate and periodised carbohydrate groups used less oxygen and were able to keep the same pace at lower fraction of VO2max. In plain English, the two carbohydrate groups improved their running economy and efficiency with the training where the keto group did not reap the benefits of the training because the cost of burning fat is so high.

Lastly, this study compared pre and post training performance walk times in a real 10km race. They found that both carbohydrate groups had a reduction in their time by 5-6% (on average 190s and 124s faster for high carbohydrate and periodised carbohydrate group). There was no improvement in the keto group and on average their times were 23s slower. There was a wide variability in performance for the keto group, ranging from 162s faster to 208s slower, meaning that keto worked for some individuals but not others.

High Fat Diet With Carbohydrate Loading

What if we don’t go into ketosis and we use a fat adaptation strategy + carbohydrate load, best of both worlds right? Havemann et al. (2006) showed that when elite cyclists consumed a high fat diet (68%) for 6 days with 1 day of carbohydrate loading that there was no significant difference in time to complete a 100km simulated bike race compared to a traditional high carbohydrate diet. However, if we look at the time to completion, we find that the high carbohydrate trial was completed on average 3 minutes 44 seconds faster (likely significant in the real world), leading us to believe that on average high carbohydrate diet may be superior to high fat diets. Again, 3 out of 8 racers on the high fat diet did improve their time compared to high carbohydrate diet, demonstrating that there may be some athletes who may respond well to a high fat diet.

More importantly, this research included 1km sprints throughout the ride to simulate a race like situation and found that the power output was significantly lower in the high fat diet group which lead to slower sprint times. Despite having lower power output in the high fat trial, they perceived they were working as hard as they were in the high carbohydrate trial. There was no difference in muscle recruitment during the sprints, meaning the high fat trial worked just as hard as the carbohydrate trial but did not achieve the same results in the sprint performance. The researchers thought that the high fat diet + a carbohydrate loading period would result in glycogen sparing due to increased reliance on fat for fuel, thus improving sprint times as sprinting relies on glucose to provide fuel. This was not the case and it is possible that high fat/fat adaptation diets reduce the ability to effectively burn carbohydrates.

Summary

  • VLCD do result in higher rates of fat oxidation during exercise
  • VLCD may reduce response to training
  • VLCD decreases economy in elite athletes
  • VLCD decreases ability to work at maximal effort which is important when there is change in work intensity- ie running up a hill, breaking away from the pack
  • Most studies show that on average VLCD negatively affect performance in endurance athletes, however there are some that may respond well
  • Remember that VLCD are not the same as training fasted or temporarily low carb diets to train your body to use fat more effectively, as this is an effective training method

In my final article in this series, I will explore the roll of supplements, the keto diet, and how that relates to athletic performance.

References:

Volek JS, Noakes T, Phinney SD. Rethinking fat as a fuel for endurance exercise. Eur J Sport Sci. 2015;15(1):13- 20.

Volek JS, Freidenreich DJ, Saenz C, Kunces LJ, Creighton BC, Bartley JM, Davitt PM, Munoz CX, Anderson JM, Maresh CM, Lee EC, Schuenke MD, Aerni G, Kraemer WJ, Phinney SD. Metabolic Characteristics of keto-adapted ultra –endurance runners. Metabolism. 2016;65(3):100-10.

Burke LM, Ross ML, Garvican-Lewis LA, Welvaert M, Heikura IA, Forbes SG, Mirtschin JG, Cato LE, Strobel N, Sharma AP, Hawley JA. Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers. J. Physiol. 2017;595(9):2785-2807.

Havemann L, West SJ, Goedecke JH, Macdonald IA, Gobson ASC, Noakes TD, Lambert EV. Fat adaptation followed by carbohydrate loading compromises high intensity sprint performance. J. Appl. Physiol. 2006;100: 194-202.

Leckey JJ, Ross ML, Quod M, Hawley JA, Burke LM. Ketone diester ingestion impairs time-trial performance in professional cyclists. Front. Physiol. 2017;8(806).

training and performance

The days of my protein rambling have almost come to an end! In my last post, I discussed how much protein should be ingested/day and how that protein should be distributed. The article before that discussed whether acute protein consumption before and activity enhances performance.iron sources

In my final article in the protein series, I want to discuss acute protein ingestion related to an acute bout of exercise. This is something that I get asked about all the time at the club: is it important to quickly ingest protein directly after a given activity to enhance recovery from that bout of training?

CLICK HERE to read the rest in the RW Magazine.

training and performance

Welcome back to another protein-focused edition of Training & Performance! My last article looked at the evidence in support of avoiding protein while you run. Today, I will discuss one of the more common questions I hear at my practice: does protein timing and distribution matter? And should you be consuming protein directly after a workout?

iron sources

Muscle/Protein Physiology

Our muscles are in a constant state of breakdown and renewal. For the average person (depending on factors such as age and level of activity), muscles are broken down and rebuilt at a rate of 1-2%/ day. To help support this renewal, the building blocks of muscle (amino acids) need to be taken in on a regular basis.

While the amino acids we ingest provide the raw material to support that 1-2% renewal rate, that is not all they do. The act of ingesting amino acids also triggers a physiological cascade that signals more muscle growth. So, when the body is being fed amino acids, not only does it have the material for muscle growth, but an anabolic muscle-building state is also put into action!

So it’s no surprise that ingesting protein is important to muscle growth. Now the question is, how much and how frequently do we need to ingest protein to optimize both of these benefits and maximize our gains?

Click HERE to read the rest in the Run Waterloo Magazine.

training and performance

I have written many times(1234)  about the importance of ingesting carbohydrates during a race (if it’s long enough).

I’ve also discussed how taking in other sources of fuel, like protein, is not the best move due to it triggering an increased risk of GI distress. The reason: in part, protein is not absorbed and metabolized as quickly as carbohydrates. Delayed gastric emptying results in water diffusing into your guts and increasing the odds of needing to take a PB-killing washroom break! iron sources

One thing I have heard in response to this tip from patients and athletes at H+P is that IF one is able to handle protein from a GI standpoint, is it worth experimenting with on top of carbohydrates as a fuel source? Is there an additional benefit to taking in protein during a race if it doesn’t bother your stomach? That is what we’ll be looking at with this article.

CLICK HERE to read the rest in the RunWaterloo magazine!

iron sources

When it comes to performance, there’s no doubt that nutrition plays a significant role. In the past, I’ve really focused on acute nutrition: what you can do directly before or during your run to be faster (i.e. here).

training and performance

An area I have neglected to focus on is what you should be doing from a nutritional standpoint on an on-going basis to stay healthy and perform at your best. One key area that I see as a recurring problem in my practice and athletes around me is iron deficiency anemia.

Iron has a number of roles in the human body. The most important function is how it is incorporated into hemoglobin and myglobin to facilitate oxygen transportation. If these proteins decline, our ability to transport oxygen to our working muscles also drops, and performance plummets along with it (such as here and here).

CLICK HERE to read more in the RW Magazine

training and performance

Well, it’s safe to say that the hot summer days of running are here! With many big races on the horizon, including the Waterloo Classic, it’s important make sure we do our best to prepare for the additional challenge heat provides.

gregIt’s a topic I wrote about briefly in the past, but this week I wanted to take a closer look at things. Two strategies I discussed before were (1) getting acclimated to the heat and (2) pre-cooling.

Both of these strategies make sense logically.  If you practice running in the heat, your body will be better equipped to handle it. In the case of pre-cooling, if you start with a cooler body temperature, then there is more wiggle room before your body really has to make the push to cool off. But what does the research show, and how well does each strategy work?

Click HERE to read the rest in the RW Magazine.

I’ve written a few times (1, 2, 3, 4) before about how important it is to ingest carbs while racing a distance that takes over ~40-60mins to enhance performance. There still seems to be some resistance to doing this; some of it is fueled by pseudoscience, but some is fueled by the very legitimate concern that ingesting 30-60g of glucose/hour will cause GI distress and potentially an even more detrimental impact on performance.

There’s no doubt, GI distress is often caused by factors other than the carbs ingested during the race (such as ingesting slowly absorbed, slowly metabolized fat, protein or fibre in close proximity to or during a race). So before trying to fix your carb situation, first make sure that it is indeed your problem.shutterstock_335916845

Training the Gut

So how do we train the gut?  And does it work?  CLICK HERE to read my latest in the Run Waterloo Magazine. 

glut med

Let’s target the hip abductor muscles! In my last article I discussed the importance of core strength and control to stabilize our trunk when we run – specifically the importance of the hip abductor muscles.

To refresh, the hip abductors help to bring the leg to the outside of our midline to counteract the moment of force where our leg naturally wants to move toward the midline each time our foot hits the ground.

We have several hip abductor muscles in our body, the majority of them are in our butt muscles! Gluteus medius (Gmglut meded), gluteus maximus (GMax), gluteus minimus (GMin) and TFL (tensor fascia latae). The focus of this article is going to be on the gluteus medius because of its important role in stabilizing the pelvis.

Why do the gluteal muscles become weak? Most of us spend our days sitting and therefore develop weak gluteal muscles making it harder to recruit them during exercise. This can lead to improper use and poor muscle patterning of other muscles to try to compensate for a weak GMed which may increase risk of injury somewhere down the road.

Using techniques to help isolate these muscles can increase their activation and ultimately improve performance. So, how do we target these muscles? A few electromyographic (EMG) studies can help us out!

Study #1: One leg vs. two legs for Gmed activation 

This study used EMG signal amplitude to measure GMed activation in 5 different weight-bearing exercises; double leg stance, single leg (SL) stance, single leg squat, single leg stance on a cushion, and single leg squat on a cushion, where the cushion was an unstable surface underneath the foot to make the exercise more difficult.

To no surprise, the results showed that a SL stance placed higher demands on the GMed than double leg stance and SL squats are more demanding than SL stance. As for the SL exercises on the cushion; the GMed muscle was activated more, but not significantly more than on flat ground.

Study #2: How do we activate Gmed even more?

This study used EMG signals to measure muscle activation patterns of the GMed (among 3 other hip muscles) during 5 unilateral weight-bearing exercises as shown here:
picss

They compared the level of activation to the subject’s maximal voluntary contraction. The EMG signal amplitude had to be between 40-60% of the maximal voluntary contraction to have sufficient intensity for strengthening.

Of the 5 exercises, the results for the GMed showed the highest amount of activation during the wall squat! The next exercises for activation were as follows: forward step-up, lateral step-up, backward step-up and then mini squat. The authors suggested that these exercises may be used as progression exercises towards the wall squat.

TFLStudy #3: What happens when the gluts are weak?

The last article looked at hip abductor muscle activity during resisted side-stepping exercises in either a squatted or standing position. They found that both the GMax and GMed had greater muscle activity during the squatted position than the upright posture. By being in this squatted position, the TFL muscle is less active which means the gluteal muscles should, in theory, be more active. This is important because if the gluteal muscles are weak, the
TFL will compensate which may lead to further underuse and weakening of the gluteal muscles.

Practical Applications

Here are a few key take home points for activating the Gmed to help enhance our running:

  • The GMed plays an important role in stabilizing the pelvis/hip joint during weight-bearing
  • GMed activation is greater when the base of support is less ie: during a side bridge, unilateral squat and lateral step up
  • Some key exercises to get the most activation from the GMed:
    • Single Leg Stance
    • Single Leg Wall Squats
    • Forward Step Ups
    • Lateral Step Ups
    • Side Steps with a resistance band around the knees/ankle (aka: Monster Walks)

And does strengthening GMed actually help to prevent injuries?  As always, the answer is that it depends, but check out this article  from Dr. Delanghe exploring how GMed strength work can decrease injury-causing variability of motion at the knee.

Happy strengthening!

vitc

Last week I spent most of the week with a mild head cold. Nothing crazy, but enough to motivate me to review my old imtraining-and-performancemunology notes yet again to relearn what I already know (it’s always fun picturing the T-cells destroying the bad stuff). Times like these also motivate me to relearn other things, like how nothing gets rid of a cold other than some basics including: sufficient rest, fluids, stress management and a good diet.

Sometimes when I’m sick, I’ll also scan the literature for new research on the common cold. Usually it’s more of the same: sleep deprivation triggers a depression in immune function, more research is needed to show if supplement X helps, excessive exercise causes a depression in immune function while light exercise may help, and so on.

However, in today’s search, I came across something new that may help us cope with the common cold. The only downside is that this new information applies to a small subset of the population. It fact it’s so specific, it’s almost not worth mentioning and learning…other than the fact that the specific subset I’m referring to is exactly who we are: athletes to train vigorously in cold weather!

What does the science say?

In general, it’s has been proven time and time again that popping vitamins does not help to speed up the recovery associated with the common cold if you are already sick. Long-term supplementation also does not help to prevent the common cold. There is some research suggesting that long term supplementation may reduce the duration of the cold, but that always sounded like a lot of effort and money for a marginal improvement on something
that rarely happens.

So I had long given up on vitamin C. Maintain a healthy diet rich and fruits and vegetables, and that was all I needed in my mind (if I achieve said goal).

Continue reading HERE in the WRS Magazine 

Custom Orthotics

Last month I wrote about how much of a difference light shoes make. In summary, the study I referenced showed losing 100g/shoe will result in just under a 1% improvement in running economy (RE) as long as all other features remain equal.

At Health & Performance, this article generated a lot of good questiontraining-and-performances. The main ones revolved around if it was good to race in the LIGHTEST shoe possible.

In response, I discussed the importance of features such as cushioning providing a boost in RE. Utilizing a shoe that completely lacks cushioning will provide a boost from lost weight, but this change will be at the expense of the spring-like action from that missing cushioning.

Where is the perfect balance?

Once I explained this, the next question became: Where is the perfect balance? How much weight in cushioning is worth it, and just how much of a boost does it provide?

My easy answer was/is to go with a lightly cushioned racing shoe that feels comfortable, and to not worry about the rest. My favourite is the New Balance 1400, which comes in at just over 200g/shoe, but does have some cushioning. The cost of that 200g, I assumed, would be more than offset with the benefits that the 200g provided. That being said, in a world where we strive to be pro-science, evidence-based and anti-fake news, I wanted to dig a little deeper to provide a more clear and proven answer.

What is light enough?

CLICK HERE to read the rest in the RW Magazine

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