Review: Scivation’s Xtend Amino Acid Supplement
“Xtend is the ultimate, sugar-free, BCAA-containing drink mix to be consumed during exercise (intra-workout). Whether you’re a physique athlete, strongman, powerlifter, traditional athlete (e.g., football, basketball, baseball, soccer, etc), endurance competitor, or just looking to significantly change your body composition through resistance training and nutrition, Xtend is ideally formulated to maximize training intensity and support your goals.”
Scivation Xtend is a basic, sort of “no frills” supplement: there are only a handful of ingredients.
Five are amino acids. There’s also a B-vitamin and some electrolytes… that’s it.
Here’s the breakdown…
Serving Size: 2 Scoops (13g)
Servings Per Container: 30
Amount Per Serving
Vitamin B6 (as Pyridoxine HCL) 640 mcg 32%
Electrolyte Blend: 1170mg
Trisodium Citrate Dihydrate, Potassium Chloride, Sodium Chloride
Citrulline Malate 1000mg
As you can see from the list, it’s really a “value added” branched chain amino acid (BCAA) supplement. The simplicity extends to Scivation’s ads for the product: there are no extravagant claims made for hyooooge gains or slabs of muscle. Rather, Scivation states Xtend will:
- Speed Recovery.
- Enhance ATP production and promote cell volumization.
- Decrease muscle breakdown and cortisol levels.
- Avoid fatigue by blocking entry of fatigue-inducing tryptophan into the brain.
- Increase protein synthesis, immune function and digestive health.
- Promote vasodilation which can lead to better assimilation and absorption of protein.
- Elevate growth hormone levels.
Let’s see how well Xtend measures up on each of these points…
Speed Recovery: Intense exercise induces muscle proteolysis and a net negative protein balance. Fortunately, recovery of a positive protein balance is facilitated by the right nutrients. In particular, the BCAA leucine serves an important function as an initiator of muscle protein synthesis (MPS).
It appears to be effective when used alone, with other essential amino acids, or even with protein. For example, in one study, a post-workout mixture of leucine, protein and carbs stimulated greater protein synthesis than a combo of protein and carbs, or carbs alone, for up to 6 hours after ingestion. The leucine drink also reduced the rate of protein oxidation.
Xtend is a good source of leucine, so should be effective for facilitating MPS and recovery of muscle protein balance after a hard workout.
Enhance ATP Production and promote cell volumization: Xtend contains citrulline malate, which has been shown to have a positive effect on aerobic energy production. The malate component is partly responsible for this. Malate is an intermediate in the Kreb’s Cycle, which is used to generate ATP—the cellular “fuel” that drives metabolic reactions in the body.
Unfortunately, the optimal dose of citrulline malate is much larger than what Xtend provides. A serving of Xtend contains only 1 g of citrulline malate, whereas a useful dose for enhancing aerobic performance is 3–6 grams.
Xtend definitely falls flat in this department.
Ditto for the “cell volumization” claim. Like taurine, glutamine has been referred to as a “cell volumizer” in ads, thanks to its function as an “osmoregulator”—that is, as a regulator of the fluid volume within cells. While supplemental glutamine is known to normalize the distribution of body fluids in trauma and other severely catabolic states, there is no evidence that it enhances the intracellular fluid volume in the muscle cells of healthy people.
Decrease muscle breakdown and cortisol levels: BCAA supplementation has been shown to suppress protein breakdown during exercise and reduce post-workout muscle soreness. Other indices of muscle damage, such as creatine kinase and lactate dehydrogenase are similarly reduced.
Avoid fatigue by blocking entry of fatigue-inducing tryptophan into the brain: Tryptophan is the precursor for serotonin, a neurotransmitter involved in depression, relaxation and mood. Increases in serotonin are thought to be responsible for exercise-induced central fatigue. BCAAs, however, can reduce fatigue by competing with tryptophan for transport across the blood brain barrier.
Increase protein synthesis, immune function and digestive health: As noted above, leucine stimulates muscle protein synthesis. In addition, glutamine plays an important role in the gut, and supplemental glutamine can promote intestinal healing in critically injured/burned patients. It may also help combat exercise-induced immunosuppression
Promote vasodilation which can lead to better assimilation and absorption of protein. As previously stated, Xtend provides a small dose of citrulline malate. Citrulline converts to arginine in the urea cycle, which in turn, is used to produce nitric oxide (NO). NO is a cellular messenger that, among other things, mediates vasodilation and improves blood flow. It has been hypothesized that the increase in blood flow also enhances the delivery of nutrients to the muscles, as well as the removal of metabolic wastes.
This claim is questionable, however, as the dose of citrulline malate is quite low.
Elevate growth hormone levels: Glutamine is a growth hormone (GH) secretagogue, and one study demonstrated a significant elevation in GH levels following a small, 2 g dose, similar to the one supplied in Xtend.
So where does this leave us?
With a fairly useful supplement, I think. A couple of the claims are a stretch, but in general, Xtend meets most of them, as a BCAA product should. As I concluded in the BCAA review, supplementation can be useful, and Xtend is certainly one way to do it.
In fact, Xtend is a pretty good way to do it. I recently gave the “Refreshing Lemonade” version a trial run, and was pretty happy with it. Like most BCAA powders, it doesn’t mix perfectly in cold water, but warm water did the trick. The taste was ok…not great, but a lot better than many pre-workout supps I’ve used. And it worked pretty well for me: I was less sore on my leg days, and experienced the usual “bump” in weights/reps that I get with essential amino acid supplements when I add them back into my stack.
For long term use, I’d consider stacking it with some extra citrulline malate, to make up for the low dose. Otherwise, Xtend looks like a pretty good product. It’s one I’d consider buying again, as it’s relatively inexpensive, tastes/handles ok and gets the job done.
|Summary of Scivation Xtend