BCAA Reviews - Machine Fuel vs. Scivation Xtend

Branched-chain amino acid (BCAA) supplements are some of the most popular are widely used products on the market. More often than not, you’ll see them included in pre, intra, or post workout supplements due to their muscle-sparing, endurance-boosting effects.

Today, we do a head to head comparison between two of the most popular BCAA supplements around MTS Nutrition Machine Fuel and the supplement that catapulted BCAAs into the spotlight - Scivation Xtend.

BCAA Review Highlights

MTS Machine Fuel profile:

  • 6g 2:1:1 BCAA
  • 2g Coconut Water
  • 1g Taurine
  • 500mg Agmatine

Scivation Xtend:

  • 7g 2:1:1 BCAA
  • 2.5g Glutamine
  • 1.14g Proprietary Electrolyte Blend
  • 1g Citrulline Malate

Flavor reviewed - Mango strawberry.

Head-to-Head Flavor Champion - MTS Nutrition Machine Fuel

Machine Fuel Ingredients

Branched-Chain Amino Acids

MTS Fuel contains 6 grams of 2:1:1 branched-chain amino acids (BCAA), meaning that each serving of MTS Machine Fuel supplies:

  • 3 grams of leucine
  • 1.5 grams of isoleucine
  • 1.5 grams of valine

Why BCAAs?

The branched-chain amino acids are a special subclass of the essential amino acids that offer two key benefits:

  • They stimulate muscle protein synthesis (via activation of the mTOR pathway), and
  • They can be oxidized (‘burned”) for energy in the muscle

The result of these two actions mean that supplementing with BCAAs, especially during training, can help prevent muscle protein breakdown, a.k.a. catabolism, as well as support energy production, thereby enhancing athletic performance. On top of that, BCAA supplementation can also help reduce soreness and muscle damage brought on by those intense training sessions, meaning less severe DOMS following leg day!

Coconut Water Powder

Intense training is almost always accompanied by profuse amounts of sweat, and subsequently the loss of a lot of water, minerals, and electrolytes. Lose enough of these nutrients, and you will eventually become dehydrated which brings with it decreased performance, reduced stamina, cramping, and increased mental and physical fatigue.

That’s where coconut water powder comes in.

Coconut water is rich in potassium, a key electrolyte that affects muscle function and athletic performance. MTS Fuel contains a whopping 2g dose of coconut water, which is about 4x as much as other BCAA supplements on the market.


L-Taurine is a nonessential amino acid found in high concentrations in the brain, heart, and skeletal muscle. As such, taurine offers a number of benefits to mental and physical performance during training.

First, taurine functions as an osmolytic compound, which is a fancy way of saying taurine improves cellular hydration by encouraging your muscles to store extra water. The additional water helps prolong endurance, protect against dehydration, and deliver some nice “water-based” muscle pumps.

Additionally, since taurine is found in the brain, it also helps reduce mental fatigue and enhance focus during training.

Agmatine Sulfate

Nitric oxide is the compound most often associated with gorging veins and massive muscle, pumps. Agmatine is a potent nitric oxide extender, that prolongs the vasodilating effects of nitric oxide by inhibiting the actions of arginase, the enzyme that degrades arginine, the primary substrate for nitric oxide production.

With arginase out of the picture, nitric oxide production remains strong all workout long, ensuring your pumps and performance never suffer.

On top of that, agmatine also serves as a neurotransmitter/neuromodulator in the brain where it can improve concentration and reduce sensitivity to pain, enabling you to push harder during workouts before succumbing to the inevitable muscle burn.

Scivation Xtend Ingredients


The main difference between Xtend and MTS Machine Fuel is that Xtend contains an additional gram of branched-chain amino acids compared to MTS Machine Fuel. All actions and benefits described above still hold true here.


The most abundant amino acid in the body, glutamine has been highly regarded as a “staple” supplement for muscle recovery and growth. It also supports gut health and immune function, too.

The issue with free from L-glutamine is that it has terrible bioavailability in the body, and when supplemented orally (as it is here) it’s almost completely broken down and absorbed in the stomach, meaning it never reaches the intestines or gets to your muscles to do the repair and recovery work it’s supposed to be doing.

While a nice ingredient in theory, you’re really not going to see much of any benefit from it here.

Electrolyte Blend

Xtend’s proprietary electrolyte blend includes a trio of electrolyte compounds including:

  • Trisodium Citrate Dihydrate
  • Potassium Chloride
  • Sodium Chloride (salt)

Similar to our discussion of Coconut Water Powder above, the electrolytes here serve to protect against dehydration and decreased performance by replenishing those vital nutrients that are lost during intense training.

Citrulline Malate 1:1

A prominent nitric oxide booster, citrulline malate is most commonly encountered in pre-workouts to improve blood flow and provide the pumps. Here, you’re getting 1 gram of 1:1 citrulline malate, which supplies 500mg l-citrulline and 500mg malic acid (malate).

That’s not enough to get significant nitric oxide production from (you need 6-8g for that), but what this amount can do is sustain the nitric oxide production you get from your pre-workout dose of Citrulline and prolong stamina from the endurance-boosting effects of citrulline and malic acid.

Head-to-Head Flavor Review

Although both products come in numerous flavors, the flavor used for the review today was one of the more recent ones in mango strawberry.

Both products mixed up seamlessly, with MTS Machine Fuel having a clear color, while Xtend had a bright reddish-orange color, due to the artificial coloring added to it.

In terms of flavoring, make no mistake both taste great and could very well serve the purpose for an intra-workout beverage. However, Xtend verges on being too sweet, even when additional water is added.

MTS Machine Fuel provides a more refreshing taste that pleasantly balances the mango and strawberry flavors. It’s “cleaner” tasting too, which can’t be said of Xtend as it has a mouth-coating effect, not the most appealing sensation to have during training. Additionally, Xtend also is very strong on the strawberry flavor, while the mango is much more subtle, almost subdued by the prominent strawberry flavor.

While both are enjoyable to drink, in the opinion of this review, MTS Fuel gets the nod due to its more balanced flavor and more refreshing taste. Xtend is a bit too sweet for us to enjoy during the workout, but could make for a fine “sipper” during the day.

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Damon Harrison - April 19, 2018

great comparison.

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