Xtend GO is yet another sequel to Scivation’s extremely popular BCAA formula, Xtend. It features the usual Xtend mix of BCAAs, Glutamine, and Citrulline, but also contains a well-formulated energy blend…FIND IT HERE
Leucine’s primary mechanism of action is via activation of Mammalian Target of Rapamycin (mTOR) which is a signaling molecule that signals the body to synthesize protein. To put it simply, Leucine activates mTOR which in turn stimulates protein synthesis.
One of the most commonly cites studies was published in the “International Journal of Sports Physiology and Performance” and found that 12 weeks of Leucine supplementation (4g/day) significantly increased 5-rep max in previously untrained (but healthy) male subjects, compared to the placebo group.
Leucine has also been shown, in multiple studies, to preserve muscle mass in individuals with certain diseases characterized by muscular wasting, further establishing Leucine as a potent anti-catabolic agent, and indicating that it is particularly useful for those with inadequate protein intake (during fasting).
Xtend GO contains 3.5g of Leucine per serving, just shy of the 4g dose used in the study mentioned above, but still an effective dose nonetheless.
Leucine does appear to be the most critical in regards to muscle protein synthesis, but Isoleucine has its own benefit pertaining to glucose uptake. In rat studies, Isoleucine has been shown to lower blood glucose and increase glucose uptake into muscle cells. While the effect of Isoleucine (in isolation) on muscle glucose uptake has not been studied in humans, BCAAs in general due appear to increase glucose uptake, and based on the rat studies this may be due to Isoleucine more so than the others.
Xtend GO contains 1.75g of Isoleucine.
Valine appears to possess the least unique benefit out of the three, but there are claims circulating that Valine may reduce mental exercise-induced fatigue by reducing the amount of Tryptophan available for Serotonin synthesis.
A 2001 study concluded that Valine lowered the amount of exercise-induced 5-HT (Serotonin) in mouse hippocampuses. During exercise Tryptophan is transported to the brain where it is converted into Serotonin. It is hypothesized that Serotonin is responsible for mental fatigue. It has also been established that BCAA directly compete with tryptophan for the same pathway to the brain, and therefore may reduce the amount of Tryptophan available for Serotonin production.
This would explain certain anti-fatigue effects of BCAA supplementation noted in a few studies. However, the claim that Valine is solely responsible for this effect is unsubstantiated by human studies. Given the current literature, it appears more likely that BCAAs in general help to attenuate fatigue.
Xtend GO contains 1.75g of Valine for a BCAA ratio of 2:1:1.
A 2009 study published in the “Journal of the International Society of Sports Nutrition” concluded that BCAAs (2:1:1) have a more pronounced effect on protein synthesis than the same amount of Leucine alone, indicating that consuming all three BCAAs is better than just Leucine.
A 2004 study conducted by the American Society for Nutritional Sciences found that BCAA requirement was significantly increased by exercise and that supplementation had “beneficial effects for decreasing exercise-induced muscle damage and promoting muscle-protein synthesis”.
A 2009 study published in the “Journal of the International Society of Sports Nutrition” tested the effects of BCAA supplementation in comparison to whey protein supplementation or simple carbohydrates (from a sports drink) in athletes. All subjects consumed the same diet and participated in the same physical training regimen. At the end of the 8 week study, the BCAA group significantly outperformed both the whey group and carbohydrate group in terms of lean body mass as well as strength.
Xtend GO packs a total of 7g of BCAAs in the classis 2:1:1 ratio.
Glutamine is a non-essential amino acid (your body can make it) that is involved in a variety of bodily functions, from immune health, to providing a back-up fuel-source for the brain. Aside from its general physiological roles, supplemental Glutamine has shown a lot of promise when it comes to fighting exercise induced immune system suppression.
Our immune systems ultimately benefit from regular exercise, but in the short-term, exercise actually temporarily lowers our immune defenses, thus making us more susceptible to infection during that time-frame. This temporary compromise of the immune system has been proven to correlate with lower levels of glutamine.
For this reason, it is suggested that increased uptake of glutamine may help keep the immune system strong post-exercise. In addition, lower glutamine levels have been recorded in over-trained athletes, suggesting that higher levels of glutamine may help to prevent overtraining.
Xtend GO contains 2500mg of Glutamine, a potentially effective dose with regards to fighting exercise-induced immune suppression.
Citrulline is usually found in pre-workout supplements, as it has been shown in multiple studies to imrove exercise performance. However, Xtend GO contains 1g of Citrulline which is much less than what has been used clinically. In the context of Xtend GO Citrulline may serve a different purpose.
There is preliminary evidence to suggest Citrulline may act in a synergistic manner with Leucine by positively affecting Leucine’s stimulation of mTOR, which is why we like seeing it in amino-based supplements.
So, even though Xtend GO contains much less than what can be considered “clinical”, we still feel Citrulline makes sense in this formula.
Scivation’s us of Theanine indicates that at least the brand is up on the current research. Considering the overwhelming amount of evidence indicating that Theanine enhances the positive effects of Caffeine AND reduces the negative effects, it amazes us that more brands don’t use it. Theanine and Caffeine is one of the few combinations that can actually be considered synergistic, rather than merely additive.
The clinically effective range for Theanine is 50-200mg, usually depending on how much Caffeine is consumed. Scivation does not disclose the exact amount of Theanine in Xtend GO but given that it is listed before Caffeine in the proprietary blend, there is undoubtedly an effective dose (relative to Caffeine).
The inclusion of Theanine helps separate Xtend GO from other BCAA + Energy supplements out there which tend to only use Caffeine.
Caffeine is a well-established ergogenic aid, oral consumption of which triggers the release of Catcholamines (Noradrenaline, Dopamine, Adrenaline, etc.), generally inducing a state of increased alertness, focus, and perceived energy.
Additionally, Caffeine can directly enhance calcium-ion release in muscle tissue, which directly increases muscle contraction force. Rather than discuss dozens of studies, we’ll leave it at this: Caffeine is an extremely effective ergogenic aid, though tolerance build-up is certainly an issue to keep in mind.
Scivation lists the amount of Caffeine in Xtend GO at 100mg per serving.
We’ve seen Sceletium tortuosum, also known as Kanna, pop up before in Scivation’s Psycho as well as MAN Sports NOOPump, but it still remains very under-researched.
Kanna contains two types of alkaloids, mesembrine tortuosamine, which are alleged to convey the psychoactive effects.
A 2011 study published in the “Journal of Ethnopharmacology” found that Sceletium tortuosum extract had limited anxiolytic effects in rats subjected to psychological stress (in the form of restraint). While no mechanism of action has been established, the results of the study indicated that the herb does not act as a serotonin reuptake inhibitor (SSRI).
Sceletium tortuosum may certainly add to the cognitive dimension of Xtend GO and, like Theanine, helps to differentiate the formula from other BCAA + Energy formulas.
THE BOTTOM LINE:
Xtend GO is a homerun for Scivation as far as we’re concerned. The BCAA + Energy category has rapidly expanded recently, as clearly there is a demand for amino acid-based products with a little “kick”. The BCAA portion of the formula is no different than any other formula, but Scivation nailed the “kick” aspect, with effective dosing of Theanine and Caffeine.
[expand title=”REFERENCES” tag=”h5″]
- Blomstrand, Eva. “A Role for Branched-Chain Amino Acids in Reducing Central Fatigue.”American Society for Nutrition (n.d.): n. pag.
- Shimomura, Yoshiharu, et al. “Nutraceutical effects of branched-chain amino acids on skeletal muscle.” The Journal of nutrition 136.2 (2006): 529S-532S.
- Anthony, Tracy G., et al. “Oral administration of leucine stimulates ribosomal protein mRNA translation but not global rates of protein synthesis in the liver of rats.” The Journal of nutrition 131.4 (2001): 1171-1176.
- Shimomura, Yoshiharu, et al. “Exercise promotes BCAA catabolism: effects of BCAA supplementation on skeletal muscle during exercise.” The Journal of nutrition 134.6 (2004): 1583S-1587S.
- Tipton, Kevin D., et al. “Stimulation of muscle anabolism by resistance exercise and ingestion of leucine plus protein.” Applied Physiology, Nutrition, and Metabolism 34.2 (2009): 151-161.
- Tipton, Kevin D., et al. “Stimulation of net muscle protein synthesis by whey protein ingestion before and after exercise.” American Journal of Physiology-Endocrinology and Metabolism 292.1 (2007): E71-E76.
- Blomstrand, E., P. Hassm�n, B. Ekblom, and E. A. Newsholme. “Administration of Branched-chain Amino Acids during Sustained Exercise ? Effects on Performance and on Plasma Concentration of Some Amino Acids.” European Journal of Applied Physiology and Occupational Physiology 63.2 (1991): 83-88.
- Anthony Anthony, Joshua C., Tracy Gautsch Anthony, and Donald K. Layman. “Leucine supplementation enhances skeletal muscle recovery in rats following exercise.”The Journal of nutrition 129.6 (1999): 1102-1106.
- MacLean D.A..Graham,T.E. and B. Saltin. “Branched-chain amino acids augment ammonia metabolism while attenuating protein breakdown during exercise.” American Journal of Physiology-Endocrinology And Metabolism 267.6 (1994): E1010-E1022.
- Stoppani, Jim, et al. “Consuming branched-chain amino acid supplement during a resistance training program increases lean mass, muscle strength and fat loss.” Journal of the International Society of Sports Nutrition 6.Suppl 1 (2009): P
- Gomez-Merino, D., et al. Evidence that the branched-chain amino acid L-valine prevents exercise-induced release of 5-HT in rat hippocampus. Int J Sports Med. 2001 Jul;22(5):317-22
- Casperson, Shanon L., et al. “Leucine supplementation chronically improves muscle protein synthesis in older adults consuming the RDA for protein.”Clinical Nutrition 31.4 (2012): 512-519.
- Sureda, Antoni, et al. “Effects of L-citrulline oral supplementation on polymorphonuclear neutrophils oxidative burst and nitric oxide production after exercise.” Free radical research 43.9 (2009): 828-835.
- Giannesini, Benoît, et al. “Citrulline malate supplementation increases muscle efficiency in rat skeletal muscle.” European journal of pharmacology 667.1 (2011): 100-104.
- Pérez-Guisado, Joaquín, and Philip M. Jakeman. “Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness.” The Journal of Strength & Conditioning Research 24.5 (2010): 1215-1222.
- Haskell, Crystal F., et al. “The effects of L-theanine, caffeine and their combination on cognition and mood.” Biological psychology 77.2 (2008): 113-122.
- Owen, Gail N., et al. “The combined effects of L-theanine and caffeine on cognitive performance and mood.” Nutritional neuroscience 11.4 (2008): 193-19
- Einöther, Suzanne JL, et al. “L-theanine and caffeine improve task switching but not intersensory attention or subjective alertness.” Appetite 54.2 (2010): 406-409.
- Giesbrecht, Timo, et al. “The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness.” Nutritional neuroscience 13.6 (2010): 283-290.
- Ebashi, S., and Mi Endo. “Calcium and muscle contraction.” Progress in biophysics and molecular biology 18 (1968): 123-183.
- Kraemer Graham, T. E., and L. L. Spriet. “Metabolic, catecholamine, and exercise performance responses to various doses of caffeine.” Journal of Applied Physiology 78.3 (1995): 867-874.
- Kraemer Graham, Terry E. “Caffeine and exercise.” Sports medicine 31.11 (2001): 785-807.
- Kraemer Graham, Terry E., Danielle S. Battram, Flemming Dela, Ahmed El-Sohemy, and Farah S.L. Thong. “Does Caffeine Alter Muscle Carbohydrate and Fat Metabolism during Exercise?” Applied Physiology, Nutrition, and Metabolism 33.6 (2008): 1311-31
- Poisner, Alan M. “Caffeine–Induced Catecholamine Secretion: Similarity to Caffeine–Induced Muscle Contraction.” Experimental Biology and Medicine142.1 (1973): 103-105.
- Smith, C. “The effects of< i> Sceletium tortuosum in an< i> in vivo model of psychological stress.” Journal of ethnopharmacology 133.1 (2011): 31-36.
- Smith, Michael T., et al. “Psychoactive constituents of the genus< i> Sceletium NE Br. and other Mesembryanthemaceae: a review.” Journal of ethnopharmacology 50.3 (1996): 119-130