Post-Run Carbs May Mean Healthier Bones

New research adds to the case for kilojoules soon after long or hard workouts.

Consuming a large amount of kilojoules not long after an exhausting run has become an accepted best practice. Consuming carbohydrates with a little bit of protein in the first 90 minutes post-run speeds muscle recovery, because in the immediate aftermath of a hard workout your muscles absorb the nutrients at up three times their normal rate. This practice might also help you maintain good bone health, suggests new research that will be published in Medicine & Science in Sports & Exercise.

British researchers had 10 accomplished male runners (sub-35:00 10K runners or sub-3:00 marathoners) do a treadmill run on three occasions. The runs were done at a steady intensity of 75 per cent of VO2 max, or somewhere between 16K and marathon race pace, for as long as possible; the average duration was 75 minutes. After the runs, the men drank the following: a placebo immediately after and two hours later; or a carb/protein drink immediately after and the placebo two hours later; or the placebo immediately after and the carb/protein drink two hours later. The carb/protein drink had a carb-to-protein ratio of 3 to 1. (For purposes of muscle recovery, the standard recommendation is a 3-to-1 or 4-to-1 carb-to-protein ratio.) The placebo contained artificial sweetener and flavouring so that the runners wouldn’t know which drink they had.

The researchers took blood samples seven times (!) between just before the start of the treadmill runs and 24 hours later. They were looking for changes in indicators of bone remodelling, and differences in those indicators among the three different post-run drink scenarios.

The key finding: three hours after the runs to exhaustion, the runners had higher levels of a type of collagen associated with bone resorption when they drank only the placebo instead of the carb-protein drink. This is significant because increased bone resorption can indicate an imbalance in bone remodeling, potentially leading to worsened bone mass and health, including the development of stress fractures. In addition, blood values of an indicator of bone formation were higher after drinking the carb-protein drink than after drinking only the placebo.

The carb-protein drink, in other words, appeared to provide some protection against the deleterious short-term effects that especially hard and/or long runs can have on bones.

Again, the workout used in this study was running at the high end of the subjects’ aerobic capacity (roughly 10-mile to marathon race pace) for as long as possible. That’s a very hard session that places tremendous strain on bones. One of the researchers, Craig Sale, Ph.D., a professor of physiology at Nottingham Trent University, told Runner’s World that consuming carbs and protein might boost bone health after other types of hard workouts.

“The post-exercise feeding may also be beneficial after longer, slower sessions as well as after shorter, high-intensity interval sessions, as all of these types of sessions include repetitive mechanical loading and cause increased physiological/hormonal responses,” Sale wrote in an email. Sale added that, for people who aren’t training multiple times per day, the post-http://www.runnersworld.com/sweat-science/is-weight-bearing-exercise-really-useless-for-bone-strengthrun feeding should be sufficiently protective for bone health as long as it occurs during the first two hours after a hard workout.

Sale doesn’t advise this practice after every run “because you will want some adaptation of the bone to training.” Indeed, other research has shown that moderate weight-bearing activity strengthens bone.

There are many commercially available sport drinks and shakes with the recommended carb-to-protein ratio. Many runners prefer chocolate milk for this purpose. Some “real-food” combos include cereal with milk or yoghurt, toast with eggs, and a bagel with peanut butter or hummus. Solid food will take a little longer to process than a drink, but if you eat it within the first two hours of your hard workout, it should be digested in time to provide the bone-protective benefits found in Sale’s study.


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