nutrient timing


By Jose Antonio, Ph.D.

One of the most effective strategies at gaining lean body mass and improving performance and recovery is via nutrient timing. That is, one should make sure that you consume nutrients (protein and carbohydrate) pre- and post-workout.

A recent study looked at the effects of supplement timing compared with supplementation in the hours not close to the workout on muscle-fiber hypertrophy, strength, and body composition during a 10-week weight training program.

In a single-blind (meaning the investigators knew what they were giving the subjects but the subjects didn’t know what they were getting), randomized protocol, resistance-trained males were matched for strength and placed into one of two groups.

The PRE-POST group consumed a supplement (1 gram of the supplement per kilogram of body weight) containing protein/creatine/glucose immediately before and after weight training.
The MOR-EVE group consumed the same dose of the same supplement in the morning and late evening. For a 176 pound person, this translates into 32 g protein, 34.4 g cho, less than 0.4 g fat, and 5.6 g of creatine monohydrate.
Guess what happened? The group that took the supplement PRE-POST had better adaptations. The PRE-POST demonstrated a significantly greater increase in lean body mass and 1-repetition maximum strength in the squat and bench press.

The PRE-POST group also had a greater increase in the size of their type II fibers (a.k.a. fast twitch) and contractile protein content. And last but not least, PRE-POST supplementation also resulted in higher muscle creatine and glycogen levels after the training program.1

Protein Supplements and Resistance Training

Another fairly recent investigation examined the long-term hypertrophic effect of protein supplementation in combination with resistance training. The study involved 14 weeks of resistance training combined with timed ingestion of isoenergetic (i.e. same calories) protein (25 grams) versus carbohydrate (25 grams) supplementation on muscle fiber hypertrophy and mechanical muscle performance. The subjects in this study were “physically active.”1

Subjects were instructed not to ingest anything else aside from plain water two hours before and two hours after the training session. On training days, the subjects consumed 25 grams of the protein or carbohydrate supplement immediately before training and immediately after the last set of the training session. On non-training days, subjects consumed one sachet (of the protein or carbohydrate supplement) mixed with water in the morning. Each sachet of protein powder contained 16.6 g of whey protein, 2.8 g of casein, 2.8 g of egg white protein, and 2.8 g of l-glutamine. Each sachet of carbohydrate powder contained 25 g of maltodextrin.

Muscle biopsies were taken from the vastus lateralis muscle and analyzed for muscle fiber cross-sectional area. Squat jump, countermovement jump, and peak torque during slow (30 degrees s-1) and fast (240 degrees s-1) concentric and eccentric contractions were determined.

After 14 weeks of resistance training, the protein group experienced an 18% and 26% increase in type I and type II muscle fiber cross-sectional area; however, no change above baseline occurred in the carbohydrate group. Squat jump height increased only in the protein group, whereas countermovement jump height and peak torque during slow isokinetic muscle contraction increased similarly in both groups.6

Thus, the most important and critical finding in this study is that physically active individuals benefit (i.e. greater muscle fiber size and enhanced squat jump performance) from timed protein supplementation in conjunction with heavy resistance training whereas carbohydrate supplementation had no effect.

Looking at diets

It is unclear why the carbohydrate-consuming group did not experience significant muscle fiber hypertrophy from the training alone. Dietary analysis showed that the two groups had the same levels of energy and protein intake before the training intervention. However, the investigators did not measure food intake during the treatment period.

It is quite possible that energy and macronutrient intake differed between groups during the intervention; however, it would seem implausible that only one group would make systematic changes in their overall diet while the other remained unchanged.

The protein supplemented group experienced a significant increase in squat jump height while countermovement jump height and peak torque during slow isokinetic muscle contraction increased similarly in both groups. It isn’t clear mechanistically why this discrepancy was found.

Nonetheless, neural adaptation (i.e. rate coding, motor unit recruitment) would explain the performance changes in the carbohydrate supplemented group. Perhaps a slight advantage in the protein supplemented group was manifest in one of the performance measures due to the fact that muscle fiber size increased only that group.

Nonetheless, it is apparent from this investigation as well as others, that consuming protein or a combination of protein plus carbohydrate is important for enhancing the adaptive response to exercise.6-14

Based on this recent investigation, it is apparent that you can consume protein/amino acids pre- and post-exercise (without carbohydrate) and get significant benefits in terms of muscle fiber size and performance. From a practical standpoint, it would make sense that athletes should be advised to consume a meal before and after training. For the sake of convenience, this meal may be best consumed as a ready-to-drink beverage.

Strength-power athletes would likely need to place greater emphasis on protein (and less so on carbohydrate) because of the dietary needs vis-à-vis skeletal muscle growth whereas endurance athletes may need proportionately more carbohydrate with protein to promote skeletal muscle glycogen repletion. Sports nutritionists must of course work with each individual to determine what works best for their particular athlete.

Practical Application Summary
It is best to consume a combination of protein and carbohydrate immediately post-exercise (as well as pre-exercise if your stomach can handle it) for promoting optimal gains in lean body mass. There isn’t a magic ratio per se in carbohydrate to protein. What is clear however is that if you don’t take advantage of this “nutrient timing” window, the benefits you incur will be less.

A minimum of 100 total calories post-workout has been shown to have significant positive benefits. If you are in the “physique” sports such as bodybuilding or fitness/figure competitions, a ratio favoring more protein than carbohydrate is likely better.