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science nutrition blog

science nutrition <strong>blog</strong>



By Steve Blechman


A recent study published in the August 2019 issue in The Journal of Human Kinetics found that protein shakes, when compared with high-carbohydrate drinks, do not reduce pain or enhance muscle recovery after a workout in resistance-trained men.       

Many people take protein shakes after a workout to help repair muscle, reduce muscle soreness, and restore performance and recovery. Research has shown that protein supplements can help people gain muscle mass and improve strength, but it’s not known whether protein shakes can speed recovery and reduce muscle pain after exercise.         

The researchers performed a double-blind study with 30 resistance-trained males aged 20 to 30. The resistance-trained males were put through an intensive resistance-training session. Ten minutes after the workout, participants consumed one of three drinks: a hydrolyzed whey protein drink, which contained 39 grams of protein and 97 grams of dextrose; another drink consisted of a skim milk protein powder and carbohydrate containing the same amount of protein; the third drink consisted of a carbohydrate drink containing 133 grams of dextrose. The three drinks were administered after resistance exercise.           

As expected, 24-48 hours post exercise, muscle soreness scores were higher but there were no differences between the experimental groups taking the three different post-workout drinks. Researchers also concluded that there was no difference between the hydrolyzed whey protein drink and the milk-protein drink in preventing muscle soreness or affecting dynamic power, compared with the carbohydrate-based drink containing dextrose. The results of the study concluded that consumption of hydrolyzed whey protein and milk protein did not “enhance recovery of dynamic power, producing ability or perceived muscle soreness,” compared to carbohydrate-based drinks only. The shortcoming of the study is the small amount of participants, only 30. Further studies are needed with larger groups to produce more reliable conclusions.         

As reported in Medical News Today, September 1, 2019, “It is also worth noting that not everyone uses these shakes for recovery. There is good evidence that protein supplements can help people gain muscle mass and improve strength.”         

Also, the scientists used no true control. As the authors write, "The recovery eliciting effects of carbohydrate-only solutions have been documented to provide significant increases in glycogen replenishment and muscle function recovery."         

Branched-chain amino acids (BCAAs) promote recovery by stimulating the mTOR pathway to increase protein synthesis to repair injured tissue. Leucine, one of the BCAAs, is the most important chemical that turns on the mTOR pathway, so it is likely that consuming leucine after exercise would be more effective (and cheaper) than consuming BCAAs. The addition of isoleucine and valine may hinder the benefits of leucine due to competition for transport into muscle cells. The BCAAs share the same active transport system into cells and muscle cells. Indeed, isoleucine and valine have been shown to inhibit absorption of leucine. In the March 2018 issue of the International Journal of Sports Nutrition and Exercise Metabolism, it was reported that men fed 6 grams of whey protein supplemented with leucine, isoleucine and valine observed less protein synthesis than whey protein supplemented with just leucine. Also, research has shown that valine can cause insulin resistance in muscle, which is detrimental to muscle growth and enhances the accumulation of body fat. Recent research has also found that valine is associated with higher risk of hypertension. BCAAs, or leucine, are best taken after exercise. BCAAs are involved in protein synthesis, tissue repair, signaling a biochemical pathway essential for muscle protein synthesis (i.e., mTOR) and blood sugar control. A meta-analysis that combined the results of seven studies showed that BCAA supplements are best taken after exercise, not before or during exercise (intra-workout). The studies revealed that BCAAs taken during exercise are “not effective on muscle soreness at follow-up time,” the researchers wrote.        

According to the meta-analysis, when BCAAs are taken after exercise, they reduce post-exercise muscle soreness and creatine kinase— a marker of muscle damage— better than rest alone.        

Benefits of leucine:

  • Leucine is the key anabolic trigger to protein synthesis.
  • Increase in muscle protein synthesis are dependent on leucine concentration.
  • 5 grams of leucine can increase the anabolic effects of protein synthesis when eating less protein, - which is ideal on a ketogenic diet.
  • Research has shown 6.25 grams of whey protein with 5 grams of leucine is equivalent to at least 25 grams of whey protein.
  • Anabolic resistance in people over 40 can be overcome by consuming greater quantities of leucine.
  • Leucine and not total protein content of a supplement is the primary determinant of muscle protein anabolic responses in healthy older people.
  • Research has shown that pure leucine is more anabolic than protein in food!
  • Leucine is the key amino acid for enhancing mTOR pathway that regulates cell growth and protein synthesis.
  • Leucine has many benefits: powering muscle growth, preventing muscle loss and enhancing recovery.


For best results as an anabolic trigger, take 5 grams of leucine (on an empty stomach) 15-30 minutes before a post-workout meal. By taking pure leucine on an empty stomach, you will get a better spike in blood levels than if you take leucine with food, because food can slow leucine’s absorption. When leucine is taken on an empty stomach, it’s a powerful metabolic switch that turns on protein synthesis. Leucine increases mTOR activity for several hours after training. When leucine is taken after resistance exercise, and before a post-workout protein-containing meal rich in essential amino acids, that’s also found in ADVANCED MOLECULAR LABS (AML)™ POST WORKOUT®, it will trigger greater protein synthesis for improved recovery and greater gains!



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