As Sterczala et al. (2015) point out in the introduction to their latest paper in the Journal of Strength and Conditioning Research, a salvage pathway is therefore required to synthesize nucleotides from exogenous sources (Gil. 2002).
As such, dietary nucleotides are necessary to maintain immune function, tissue growth and cellular repair. Sounds familiar? Yeah, all of those functions are affected by exercise, which can (at least temporarily) significantly increase one's nucleotide demands to levels that cannot be supplied by endogenous (=the body's own) synthesis, alone. A recent study which shows that the blunted hypertrophic response in aged skeletal muscle is associated with decreased ribosome biogenesis even suggest that this may be one of the reasons old muscle won't grow (Kirby. 2015). Consequently, there has been a growing interest in the potentiaL implications of exogenous nucleotide supplementation on exercise-induced immune
"Aside from increases in salivary immunoglobulins, McNaughton et al. (2006 & 2007) have observed a decreased cortisol response to exercise, which would partially explain the reduced immunosuppression. Animal models have observed similarly attenuated cortisol responses to stressful stimuli (Palermo. 2013, Tahmasebi-Kohyani. 2012). Given the roles of cortisol in gluconeogenesis and glycogenolysis, a reduced cortisol response may indicate a reduction in the metabolic stress of the exercise bout as a result of nucleotide supplementation. In the days following stressful exercise, [chronically (!) | see red box to learn why this is important] elevated cortisol levels could impair recovery, as cortisol can increase protein degradation and inhibit protein synthesis (Hickson. 1993; Kraemer. 2005)" (Sterczala. 2015).So, while we don't want to block the cortisol response to exercise altogether (here's why), Sterczala et al. are right: Attenuating or controlling it may quite beneficial. Especially if this attenuation occurs in the days after the exercise-stressor, when you want your cortisol levels to return to normal. Unfortunately, Ostojic et al. (2012 & 2013) and McNaughton et al. (2006 & 2007) who have already demonstrated the beneficial effects of nucleotide supplementation following acute exercise, did not control for the immune and cortisol response during the recovery period after the exercise stimulus. In addition, their studies involved cycling and running exercises which are, as Sterczala et al. rightly point out, "quite different in terms of muscle recruitment and metabolic demands when compared to heavy resistance exercise" (Sterczala. 2015). Therefore, the effects of nucleotide supplementation on the response patterns to resistance exercise are currently unknown and thus the perfect research object for a new study - Sterczala et al.'s new study.
|Only the cortisol, not the GH, IGF-1 or testosterone response to exercise correlate w/ increased lean mass gains in response to 12w of resistance training (West. 2012).|
Each cycle (placebo - PL; nucleiotides - NT) began with a two week loading phase in which subjects took the supplement while maintaining their normal exercise routines. At the beginning of the third week, an acute heavy resistance exercise protocol (AHREP) was completed. To assess the effects on recovery, subjects reported to the laboratory 24, 48 and 72 hrs following the AHREP for additional blood draws and performance testing. Before and after the the acute heavy resistance exercise protocol (AHREP), and at 24, 48, and 72 hrs thereafter, blood samples were analyzed for cortisol, myeloperoxidase, and absolute neutrophil, lymphocyte and monocyte counts. Creatine kinase was analyzed pre-AHREP and at 24, 48, and 72 hrs post-AHREP. Performance measures, including peak back squat isometric force and peak countermovement jump power were also analyzed.
"The nuBound® (Nu Science Laboratories, Inc., Boston, MA [the sponsor of the study]) supplement contains dietary nucleotides, which are extracted from yeast (saccharomyces cerevisiae). During the supplement treatment cycle, subjects took two capsules of nuBound® daily, one upon waking, and one following exercise. The two capsules (1000mg) contained 278mg of dietary nucleotides, 375mg amino acids (l-glutamine, l-methionine, l-lysine), riboflavin (4.5mg), folate (400mcg), biotin (188mg) and pantothenic acid (12mcg). Other ingredients included fructo-oligosaccharides (chicory root), inositol and sodium citrate.
Do you remember that protease supple- mentation (e.g. 1,000mg Bromelain) has recently been shown to have ergogenic effects in athletes, too?
During the placebo cycle, subjects followed a dosing schedule identical to the supplement cycle. The placebo capsules were identical in size, shape and color to the nucleotide supplement but contained only lactose and magnesium stearate. During the first treatment cycle, subjects recorded their daily dietary intake on a diet log. The log was then used to help subjects replicate their diet during the second treatment cycle. Subjects also replicated their activity protocol during the study for each cycle" (Sterczala. 2015)."
|Figure 1: Effects of nucleotide (NT) and placebo supplement (PL) preload for two weeks on cortisol (~stress) and creatine kinase (~muscle damage) response to exercise (Sterczala. 2015).|
|Figure 2: While the improved cortisol and CK are nice to see, only the accelerated force recovery in the isometric back-squat test may actually be practically relevant for athletes (Sterczala. 2015).|
- Gil, A. "Modulation of the immune response mediated by dietary nucleotides." European Journal of Clinical Nutrition 56 (2002): S1-4.
- Hickson, et al. "Exercise and inhibition of glucocorticoid-induced muscle atrophy." Exercise and sport sciences reviews 21.1 (1993): 135-168.
- Kraemer, William J., and Nicholas A. Ratamess. "Hormonal responses and adaptations to resistance exercise and training." Sports Medicine 35.4 (2005): 339-361.
- Kirby, et al. "Blunted hypertrophic response in aged skeletal muscle is associated with decreased ribosome biogenesis." Journal of Applied Physiology 119.4 (2015).
- Mc Naughton, L., D. J. Bentley, and P. Koeppel. "The effects of a nucleotide supplement on salivary IgA and cortisol after moderate endurance exercise." Journal of sports medicine and physical fitness 46.1 (2006): 84.
- Mc Naughton, Lars, David Bentley, and Peter Koeppel. "The effects of a nucleotide supplement on the immune and metabolic response to short term, high intensity exercise performance in trained male subjects." Journal of sports medicine and physical fitness 47.1 (2007): 112.
- Ostojic, Sergej M., and Milos Obrenovic. "Sublingual nucleotides and immune response to exercise." J. Int. Soc. Sports Nutr 9 (2012): 31.
- Ostojic, Sergej M., Kemal Idrizovic, and Marko D. Stojanovic. "Sublingual Nucleotides Prolong Run Time to Exhaustion in Young Physically Active Men." Nutrients 5.11 (2013): 4776-4785.
- Palermo, Francesco Alessandro, et al. "Effects of dietary nucleotides on acute stress response and cannabinoid receptor 1 mRNAs in sole, Solea solea." Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 164.3 (2013): 477-482.
- Sterczala, et al. " The Physiological Effects of Nucleotide Supplementation on Resistance Exercise Stress in Men and Women." Journal of Strength and Conditioning Research (2015): Publish Ahead of Print.
- West, Daniel WD, and Stuart M. Phillips. "Associations of exercise-induced hormone profiles and gains in strength and hypertrophy in a large cohort after weight training." European journal of applied physiology 112.7 (2012): 2693-2702.