Nutrient timing and athletic performance

If you’re the sort of person who just likes to see the result of something, feel free to scroll down to the last paragraph for the take home message of this post.

Nutrient timing is all about focusing on when to eat, not only what to eat and there are four main principles that we, as coaches and athletes need to be aware of:

1.       Enhancing the performance of individual training sessions.

2.       Enhancing recovery following training

3.       Enhancing net protein balance (providing an anabolic environment), and

4.       Enhancing the adaptations to training programs over the long term.

I’m going to use this blog in the context of the strength/power training athlete (weightlifter, powerlifter, strongman, discus/shotput/javelin, sprinter etc).  However the principles are applicable to longer duration training with some adjustments.

Strength/power training is primarily anaerobic.  The athlete will use ATP-PC and stored glycogen for fuel during the workout, as well as small amounts of fat.  Fat is generally not utilised during the workout as an energy source as beta oxidation is too slow of a process to generate the amounts of ATP necessary for high intensity anaerobic training.

With this in mind, there really hasn’t been any conclusive evidence that supplementing with carbohydrates (CHO) or protein BEFORE an individual training session has much benefit FOR THAT SESSION.  However, this is not to say that it isn’t a good idea, as supplementation with both protein and carbohydrates has benefits in the longer term and in recovery.

Longer term effects of supplementation and timing of nutrients

An intense resistance training session can reduce muscle glycogen by 25-40%, depending on the session.  If this isn't replenished, subsequent workouts will suffer. It is therefore important to replenish you muscle glycogen, especially if you're doing more than one workout a day, or workouts clustered together (you crazy crossfitters you!)  

However, this is not to say that you can go and scoff down three kilos of sweet potato as there is a limit on the rate of muscle glycogen synthesis of about 1g/kg/hour.  This level has been shown to replace up to 90% of muscle glycogen.  This seems like a lot, however, remember that your body is primed after exercise to use whatever you put in it for recovery and adaptation to training, not storage.  It does get better however, as studies has shown that ingesting both protein and CHO directly following a workout will replenish muscle glycogen faster than CHO alone and do so with less CHO, around 0.67g/kg/hr.  This leads to faster recovery and the ability to hit high intensity workouts sooner and do so with more energy.

Protein/amino acids and muscle damage

A well as replacing lost glycogen, efficient recovery also includes reducing muscle damage.  Even a small amount of protein (10g essential amino acids) ingested after physical exertion has been shown to be enough to stimulate muscle recovery and reduce muscle damage, as shown by the blood levels of creatine kinase.

Of the essential amino acids, three have been shown to significantly reduce muscle damage, as much as a full dose of EAA’s.  These are the branched chain amino acids leucine, isoleucine and valine.  An equivalent dose of BCAA’s was shown to be more effective than whole protein sources at reducing muscle damage and aiding recovery.  This study also investigated the effect of supplementing with BCAA’s on DOMS and found that they caused a significant reduction in subjective levels of DOMS compared to the whole protein and control groups.

In summary, taking a CHO /protein supplement immediately following training will replenish muscle glycogen and BCAA’s will reduced muscle damage and DOMS.  This would be especially important for people competing in multiple workout events, hint hint.

Net protein balance

The central focus of resistance training is maximising the anabolic response.  This includes having a positive protein balance and an anabolic environment (building, not breaking down).  There are three ways we can do this, increase protein synthesis, decrease protein breakdown, or a combination of both.

EAA’s have, when ingested after training have been shown to cause an improvement in net protein balance and stimulate an anabolic environment with whey protein being shown to be superior to both casein and soy proteins.

Not surprisingly, when both CHO and protein are ingested directly after exercise, there is a significant increase in muscle protein synthesis which is greater than only taking a protein supplement.  It appears that EAAs/protein taken directly after a strength/power training session enhances protein synthesis and supplementing this with CHO inhibit protein breakdown.

The take home message…

To maximise any training program, you need the right nutrition.  This isn’t only a case of what to eat but also when to eat it.  We’ve seen in this post that supplementing your training with both CHO and protein directly after exercise will enhance muscle glycogen synthesis, inhibit protein breakdown and enhance protein synthesis.  Additionally, supplementing with BCAA’s will decrease muscle damage and hence improve recovery and decrease DOMS.  This has the effect over the course of a training program and enhances recovery and adaptation to the stimulus.