Is Drinking Milk Or Eating Beef Better For Recovery After Exercise?

Picture by Steve p2008 from Flickr

After your workout, is drinking milk better or eating beef better for recovery? Make a quick guess before you read on.

That was the basic question the authors wanted to find out. The impact of beef and milk as a protein source as a post workout meal.

Here's what made this study unique and interesting.The researchers injected a cow with amino acids specially labelled with a rare isotope of carbon. After that they milked the cow and had it slaughtered to produce meat. The researchers then used the specially labelled milk and meat to feed the subjects in their trial.

This allowed the researchers to track where the protein went through muscle biopsies after the subjects did a strength training session.

The subjects consume 30 grams of protein from either 350 ml of skim milk or 158 grams of ground beef. Rate of protein synthesis (how quickly your body is building new muscle) were as follows.

Picture from Am J of Clinical Nutrition

Milk clearly has the edge two hours after working out. However, after five hours, the rates of protein synthesis were similar.

Other than using the same cow for both milk and beef, this study differs from previous studies as soy protein or whey powder is commonly used in other studies.

The researchers suggested that there may be larger differences between milk and meat if the amount of protein consumed were smaller. 

Personally I would like to know if other kinds of protein such as eggs, chicken or other vegetable proteins will produce different results.

References

Burd NA, Hamer HM et al (2013). Substiatial Differences Between Organ And Muscle Specific Tracer Incorporation Rates In A Lactating Dairy Cow. Plos One. DOI:10.1371/journal.pone.0068109.

Burd NA, Gorissen SH et al (2015). Differences In Postprandial Protein Handling After Beef Compared With Milk Ingestion During Postexercise Recovery: A Randomized Controlled Trial. Am J Clin Nutr. 102(4) 828-836. DOI: 10.3945/ajcn.114.103184.

Carbohydrates Still The Best Energy Source For Racing

Picture by Erik Stattin from Flick.

Stick to your carbohydrate diet if you want to race well? Or train your body to burn more fat to be more effective in sustaining your effort. Much has been debated over how much carbohydrates and fat we need in our diet to enhance running (or endurance) performance.

Since our bodies can only hold limited amounts of muscle glycogen (or carbohydrates), we usually "hit the wall" after about 20 miles of running. Our bodies store large amounts of fat and if we can utilize the fat stores, we can potentially rely less on carbs.

And fat-adapted running diet is getting popular, especially in the long/ ultra distance running community in an attempt to teach their bodies to use fat (instead of carbs) for fuel.

Prominent exercise physiologist Tim Noakes has suggested that training your body to burn more fat is a more effective way to sustain effort (especially in a long race). Noakes may be right about utilizing fat for ultra distances and we await more research from him.

But carbs may be better if you are running high intensity intervals or racing hard and fast, so says a recently published research.

The researchers studied a group of male competitive runners in four randomized trials running on a treadmill at a speed of 95 per cent of their best half marathon time to exhaustion.

The runners consumed a pre run meal before each trial with different nutritional values. Runners in the first two trials were fed carbs in the form of a jelly. Runners in the next two trials fasted overnight and were given a jelly that looked and tasted the same to the carb group but contained no calories.

Runners in trials two and four were given nicotinic acid which prevented the use of fat stores during testing. This is to test whether blocking the use of fat as a fuel hampered run performance.

Results showed that majority of the time, (83-91 per cent) carbohydrates were the source of primary fuel. The nicotinic acid did not affect the runner's performance or the body's ability to use carbohydrates as fuel. The runners did use a small amount of fat as fuel, but the main source was still carbohydrates.

Your friends or other runners may want to experiment with utilizing more fat to fuel their runs, but this study shows that at least for races up to half marathon, carbohydrates are still best for getting you to the finish line or clocking your personal best timing.


Reference

Lackey JJ, Burke LM et al (2015). Altering Fatty Acid Availability Does Not Impair Prolonged, Continous Running to Fatigue: Evidence For Carbohydrate Dependence. J App Physiol. DOI:10.1152/japplphysiol.00855.2015.

**Note from a runner

A friend who's been on a low carb,  high fat Paleo diet shared that adding carbs back to his diet can be discouraging. For every ounce of carbohydrate he ate after training his body to be used to low carbs, his body stored three ounces of water. His weight shot up quickly.

You Should Not Be Heel Striking

Picture by richseow from Flickr

In the picture above, you can see clearly the lead runner and a few others behind him heel striking whilst running. So is heel striking bad?

A group of Danish researchers studied runners who landed on their heels while running, The runners had a personal best time of 17 minutes or slower for 5 km.

In the study, the runners ran 1 km on a track with a force plate at three different speeds. 8 km/ hour (about 12 min/ mile), 11.79 km/ hour (8:20 pace) and 15.78 km/ hour (slightly over 6:00 pace).

The results showed that the total load on the front of the knee actually increases with slower running. This can cause or aggravate anterior (or front) knee pain, also commonly known as runner's knee.

Although the load on the runners' knees was higher on each stride during faster running, the runners took more strides to cover the same distance if they ran slower. As a result, the runners accumulated 80 per cent more load on the front of their knees when they ran at a slower pace.

The results explain why running more mileage (and heel striking) is linked to pain at the front of the knees. This also explains why runners with knee pain who switched to running with minimalist type shoes with the correct technique stopped having knee pain. Note that it has to be correct technique, otherwise the impact can be 7 times greater.

The authors suggest that if you are a heel striker with knee pain you may want to consider running shorter distances at a faster pace to limit the cumulative loads on your knees.

Well, better not heel strike when you run to avoid getting knee pain in the first place.

Reference

Petersen J, Sorensen H et al (2015). Cumulative Loads Increase At The Knee Joint With Slow-speed Running Compared to Faster Running: A Biomechanical Study. J Orth Sports Phy Ther. 45(4): 316-322. DOI: 10. 2519/jospt.2015.5469.