Research Review: Nutrition and Exercise Recovery – Part 2

In Part 1 of this article, we explored how JB set up an experiment to explore whether protein and carbohydrate supplementation affected recovery from an intense hour-long cycle in trained athletes. As you may remember, the athletes were split into two groups: one that received a carb-only supplement after an initial hard exercise session, and one that received a carb plus protein supplement. (Actually, there were three groups — to rule out as many unrelated factors as possible, a third group was given a placebo.)

Part 1 also gave us a peek into JB’s brain and taught us a few tricks of the scientific trade. This week, we’ll discover what he found out.

Results

Performance

First, both of the supplemented groups, carb+protein and carb only, didn’t bike as far in the afternoon exercise (aka the PM_ex) session. Not a surprise. Even tough, seasoned athletes get tired after busting their butts for an hour.

Now to answer the big question: Does carb+protein work better than carb alone to recover from aerobic exercise? YES!

The group of cyclists that were given the carbohydrate and protein drink did better in the afternoon session compared to the group that received only carbohydrates. They were able to cycle longer and faster, as shown in Table 1 below.

Although neither group cycled as far in the second session as in the first, the carb+protein group cycled, on average, 300 metres less in the PM_ex session than their AM_ex. In contrast, the carb only group were, on average, 1.05 kilometres short of their morning performance –- a difference of 750 m between the two groups!

This is especially significant if you remember that the cyclists were going up a 7% grade — approximately equivalent to one of the toughest mountains in the Tour de France. In this situation, every hard-won metre counts for a lot more than on a nice flat track.

Figure 1 below compares the three groups: carbohydrate + protein (C+P); carbohydrate-alone (CHO); and placebo (PLB).

Table 1: Average distances for the test day (in kilometres)

Figure 1: Decreases in performance from morning to afternoon sessions (in kilometres)

Comparison of carbohydrate + protein (C+P); carbohydrate-only (CHO); and placebo (PLB).

Not only was performance enhanced in the carb+protein group compared to carb alone, but so was power output. Since speed is based on power output, and distance is time x speed this makes perfect sense.

Fuel use

There was no difference in carbohydrate utilization, serum glucose, and lactate between groups. But there was a difference in fat utilization between groups in the PM_ex session: the carb+protein group utilized more fat.

Other studies have also shown that high protein meals during exercise can increase fat usage more than carbohydrate meals.¹ One reason seems to be the increase in insulin with carbohydrate meals. Since insulin inhibits lipolysis (fat breakdown), it could be that higher insulin (which is triggered by carbohydrate) reduces fat utilization.

How does a carbohydrate and protein drink increase fat usage? Taking in protein increases plasma glucagon that then stimulates lipolysis, so you use more fat.²

Recovery and re-synthesis

Another important difference between groups was the rate and amount of muscle glycogen re-synthesis.

A couple years ago, JB did a study that used a procedure very similar to the one I just described, in which he compared the amount of muscle glycogen in the two groups.³

NMR spectra

The cool part is how he measured vastus lateralis muscle glycogen. He used NMR (nuclear magnetic resonance)! Very cool. NMR is the basis for magnetic resonance imaging (MRI). In fact, an MRI is sometimes called NMR-I (nuclear magnetic resonance imaging). Using NRM, you can scan and identify what molecules are in your sample. For those in the know, the specific type of NMR that JB used was natural abundance 13C-NMR.⁴

Compared to the old standby of needle muscle biopsy, NMR is much less invasive and allows for infinite measures without affecting the muscle. Needle muscle biopsy not only takes a sample of muscle, but also causes damage that leads to bleeding, swelling and muscle soreness. NMR allows researchers to scan the entire muscle instead of taking one small sample and hoping that it represents the whole thing.

This is an important concept in understanding research: how you ask the questions and gather the data can affect what you find. The biopsy procedure itself has an effect on the experimental results, and researchers may err in assuming that the small sample they extracted truly represents the entire muscle.

In addition to his choice of a highly sensitive and sophisticated measurement technique, JB designed the experiment slightly differently the second time around, which also affected the results. In the earlier experiments the cyclists weren’t paced with previous performances and subsequently there was no difference in glycogen between groups.

This time around JB changed the study design and found that there were, indeed, differences. As Figure 2 below shows, this more recent study showed that the carb+protein group (red bar) were faster at making glycogen after their AM_ex session than the carb alone group (gray bar) or the placebo group (blue bar). Six hours after the AM_ex session the carb+protein group had 22% more glycogen than carb alone.

Conclusion

This research showed that if you’re a long-distance cyclist or runner, then you should definitely use a mix of protein and carbohydrates to recover from your race or training session. Great!

But what if you aren’t that interested in endurance cycling or running? Well, other sports activities also benefit from using carb+protein drinks.  One key insight from this study was that carb+protein improved overall recovery and performance in subsequent training sessions.  How many of you have been in tournaments with multiple games or events in one day? Soccer, basketball, tennis and hockey are examples of sports that routinely involve multi-day tournaments, with each day having up to 4 games. One long event can deplete your glycogen but so can multiple bouts of shorter events. Without proper recovery nutrition, you could easily “hit the wall” in the middle of your 5th basketball game in 2 days.

So, for both long-distance and multi-event athletes, a carb+protein supplement immediately following exercise bouts is a good idea.

References

1. Rowlands DS, Hopkins WG. Effect of high-fat, high-carbohydrate, and high-protein meals on metabolism and performance during endurance cycling. Int J Sport Nutr Exerc Metab. 2002 Sep;12(3):318-35.

2. Calbet JA, MacLean DA. Plasma glucagon and insulin responses depend on the rate of appearance of amino acids after ingestion of different protein solutions in humans. J Nutr. 2002 Aug;132(8):2174-82.

3. Berardi JM, Price TB, Noreen EE, Lemon PW. Postexercise muscle glycogen recovery enhanced with a carbohydrate-protein supplement. Med Sci Sports Exerc. 2006 Jun;38(6):1106-13.

4. Jue T, Rothman DL, Tavitian BA, Shulman RG. Natural-abundance 13C NMR study of glycogen repletion in human liver and muscle. Proc Natl Acad Sci U S A. 1989 Mar;86(5):1439-42.