Recovery Nutrition: Should you bother?

News Written by Richard Harris

Nutrition strategies for training and competition are vital in order to help you achieve the most from your sport. It is quite common however to find that individuals are either unaware, or do not quite understand this subject, neglecting their nutrition, thus neglecting their sporting performance.

In the first of a three-part series, this article concentrates on the importance of recovery and post exercise nutrition strategies, something we at MPN find people are often first to neglect. 

How many words: 1742!

How long to read: 5 minutes.

Recovery – should I bother?

Put simply, if you are looking to maintain or enhance exercise performance, whether in training or competition, then absolutely!

Key Point: after prolonged endurance activity, our bodies are in a depleted state and require the ingestion of several nutrients in order to begin the repair and regeneration process.

Thinking of it in a different context, when your car runs out of petrol, what do you do…?

There are several determining factors contributing towards successful sporting performance in a nutrition sense. Arguably, the most important factor is carbohydrate availability, specifically in the form of muscle and liver glycogen (stored carbohydrates).

Carbohydrate – our fuel

Carbohydrates (CHO), along with fatty acids are the main sources of energy substrates during endurance activity (1). The substrate that provides the greatest contribution of energy depends upon several factors including training status of the individual, and the duration and intensity of the activity being performed.

Our stored muscle and liver glycogen represents only approximately 5% of the total energy stores within our body (1), yet during moderate and high intensity prolonged endurance activity, these stores contribute more than 50% of the energy required (4). During near maximal, interval or resistance type activity, the contribution of energy from CHO could be even greater, highlighting the importance of CHO availability.

Key Point: Evidence has highlighted that muscle and liver glycogen levels can reduce by up to 75% after just 3 hours of cycling at 70% VO2max* (low intensity activity) (1).

Ok so I need carbs…

Yep!

As discussed previously our body only stores very little CHO, roughly enough to fuel just 90 minutes of moderate to high intensity activity (2). As is often the way with prolonged endurance activity, we can require energy for hours at a time. For example, an endurance cyclist may be in the saddle for up to 4 to 5 hours at a time.

Key Point: This further highlights the importance of exogenous (from ‘outside’ the body) CHO ingestion before, during and after activity, as our stores will be ‘empty’ after 90 minutes if the intensity is moderate to high.

As we are focusing on recovery, we will focus on the importance of CHO ingestion post exercise.

Carbohydrates post exercise… Pass me the beer!

Ok. We think we have bored you enough with the importance of CHO for fuelling exercise. But why is it important to ingest CHO after exercise and not just before and during?

For those taking part in moderate to high intensity prolonged endurance or resistant type activity, it is vital to begin replenishing CHO as soon as possible post exercise. It is particularly important for individuals performing back to back/multiple training sessions throughout a week, as evidence suggests these individuals will have higher rates of CHO usage to fuel activity (2).

Key Point (!): Unfortunately, we hate to be the bearers of bad news, but beer isn’t quite the ideal CHO replenisher!

Just a little bit of science… Stay with us!

The rate at which muscle and liver glycogen levels are replenished all depends upon how quickly CHO is ingested after exercise.

Key Point: It is suggested that this phenomenon: post exercise glycogen repletion, is THE most important aspect determining how quickly one recovers from a bout of moderate to high intensity activity (1).

Traditionally, researchers have described a ‘window of opportunity’ to maximise glycogen repletion post exercise. Evidence suggests CHO repletion levels can drop by up to 90% if ingestion does not occur immediately following exercise (3). Put simply, you are reducing your rate of recovery, and potentially reducing the performance enhancing adaptations to exercise.

In scientific terms, there are thought to be two phases to glycogen repletion. The first ‘rapid’ phase occurs 30 – 60 minutes post exercise (1), and is mediated by the high rate of glucose transport into the cell, by the glucose transporter – 4 (GLUT-4) (4). Evidence suggests the majority of GLUT-4 are bound to stored glycogen; glycogen depletion following exercise therefore causes an increase in available ‘free’ GLUT-4 (5). Furthermore, decreases in muscle and liver glycogen levels stimulates the activity of the enzyme glycogen synthase**** (6). Suggestions are that repeated muscular contractions during exercise, also stimulates the activity of glycogen synthase, therefore highlighting the increased potential to store CHO post exercise (6).

The second phase of glycogen repletion is through an increased sensitivity of our cells to the hormone insulin (5). It is suggested the increased sensitivity to insulin can last for up to 48 hours post exercise, where by CHO repletion must continue to occur, although to lesser intensities (1).

The take home message here is that CHO should be ingested immediately, or as soon as is viable after exercise has ceased.

Key Point: In order to promote the optimal environment for CHO replenishment, it is suggested that a CHO with a high glycaemic index**, and a high bioavailability*** should be ingested as part of a post exercise beverage (1). This is one of the reasons we chose Karbo-Lyn™ as the CHO in our myrecovery product.

It’s not just about carbs…

Prolonged endurance activity not only serves to deplete our substrate levels, but also causes metabolic stress, and thus sets about stimulating remodelling of various structures such as our skeletal muscles, which in turn helps enhance our future exercise performance, provided the necessary nutrition is available.

Key Point: Evidence suggests the ingestion of a post exercise beverage containing a combination of CHO and protein can exaggerate the release of insulin, part of the ‘window of opportunity’ described earlier (8).

It is suggested the increased levels of insulin could cause a greater rate of stored CHO within more ‘insulin sensitive’ cells, such as our liver and skeletal muscle, leading to an efficient way of promoting glycogen repletion in tissues that require CHO to a greater extent; tissues involved heavily in exercise (1). This is particularly important for individuals training and competing more frequently, as they will have less time in between exercise bouts for replenishing glycogen levels.  

How much?

In order to maximise recovery, individuals should aim to ingest up to 1.2 g of CHO per kg of bodyweight per hour (1), for up to 4 hours post exercise (2)... Phew!

For some, this can equate to A LOT of CHO, and can be very impractical! This however is where the benefit of the co-ingestion of CHO and protein is at its maximum. Consuming approximately 0.25 g of protein per kg of bodyweight, per hour, OR, a maximum dose of 20 g of protein, can augment the same glycogen repletion rates but alongside a smaller than recommended dose of CHO (7), due to the exaggerated insulin spike discussed previously. Any more than 20 g of protein has not been suggested to promote additional benefits with regards to recovery however. (1).

This combination of a smaller dose of CHO and protein will not only benefit muscle and tissue remodelling and repair, but also provide a more practical way of ingesting CHO, as for some, the recommended CHO amounts for optimum recovery could be seen as rather a lot!

See here for the amounts of CHO and protein included within our myrecovery product.

To sum up…

As well as the benefits of ingesting CHO and protein together in a post exercise beverage, several other nutrients, for example creatine and electrolytes, have been highlighted as vitally important in promoting the recovery needed in order to improve performance. These nutrients however are beyond the scope of this article.

Please see the article here, containing more information as to why these other vital nutrients are so important.  

Key Point: For those looking to progress in their sport and exercise, it is of paramount importance to optimise post exercise nutrition after bouts of moderate to high intensity endurance and resistance activity.  Those who succeed in doing so will promote performance enhancements during subsequent bouts of training, and therefore competition.

We hope this article has been helpful!

Thanks for reading!

Team MPN

* VO2max is defined as our maximal oxygen uptake. It is considered to be one of the gold standard methods of measuring aerobic fitness.

** the glycaemic index is a ranking of carbohydrate foods. Foods are ranked based on how they affect blood glucose levels.

*** the bioavailability of a nutrient is defined as the amount ingested capable of being absorbed and available for use or storage.

**** glycogen synthase is an enzyme responsible for converting glucose into stored glycogen.

References:

1) Beelen, M., Burke, L.M., Gibala, M.J. and van Loon, L.J.C. (2010) ‘Nutritional Strategies to Promote Postexercise Recovery’, International Journal of Sports Nutrition and Exercise Metabolism,20 (6), pp. 515 – 532.

2) Beck, K.L., Thomson, J.S., Swift, R.J. and von Hurst, P.R. (2015) ‘Role of nutrition in performance enhancement and postexercise recovery’, Open Access Journal of Sports Medicine, 6, pp. 259 – 267.

3) Price, T.B., Rothman, D.L., Taylor, R., Avison, M.J., Shulman, G.I. and Shulman, R.G. (1994) ‘Human muscle glycogen resynthesis after exercise: Insulin-dependent and independent phases’, Journal of Applied Physiology, 76 (1), pp. 104 – 111.

4) Richter, E.A., Derave, W. and Wojtaszewski, J.F. (2001) ‘Glucose, exercise and insulin: Emerging concepts’, The Journal of Physiology, 535 (2), pp. 313 – 322.

5) Jentjens, R. and Jeukendrup, A. (2003) ‘Determinants of postexercise glycogen synthesis during short-term recovery’, Sports Medicine, 33 (2), pp. 117 – 144.

6) Nielsen, J.N., Derave, W., Kristiansen, S., Ralston, E., Ploug, T. and Richter, E.A. (2001) ‘Glycogen synthase localization and activity in rat skeletal muscle is strongly dependent on glycogen content’, The Journal of Physiology, 531 (3), pp. 757 – 769.

7) Moore, D.R. (2015) ‘Nutrition to Support Recovery from Endurance Exercise: Optimal Carbohydrate and Protein Replacement’, Nutrition and Ergogenic Aids, 14 (4), pp. 294 – 300.

8) Kaastra, B., Manders, R.J., Van Breda, E., Kies, A., Jeukendrup, A.E., Keizer, H.A. and van Loon, L.J. (2006). ‘Effects of increasing insulin secretion on acute postexercise blood glucose disposal’, Medicine and Science in Sports and Exercise, 38 (2), pp. 268 – 275.

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