Top

Journal of the International Society of Sports Nutrition

Published in:

Open Access 01-12-2017 | Research article

Effects of ingesting a pre-workout dietary supplement with and without synephrine for 8 weeks on training adaptations in resistance-trained males

Authors: Y. Peter Jung, Conrad P. Earnest, Majid Koozehchian, Minye Cho, Nick Barringer, Dillon Walker, Christopher Rasmussen, Mike Greenwood, Peter S. Murano, Richard B. Kreider

Published in: Journal of the International Society of Sports Nutrition | Issue 1/2017

Abstract

Background

The purpose of this study was to examine whether ingesting a pre-workout dietary supplement (PWS) with and without synephrine (S) during training affects training responses in resistance-trained males.

Methods

Resistance-trained males (N = 80) were randomly assigned to supplement their diet in a double-blind manner with either a flavored placebo (PLA); a PWS containing beta-alanine (3 g), creatine nitrate as a salt (2 g), arginine alpha-ketoglutarate (2 g), N-Acetyl-L-Tyrosine (300 mg), caffeine (284 mg), Mucuna pruiriens extract standardized for 15% L-Dopa (15 mg), Vitamin C as Ascorbic Acid (500 mg), niacin (60 mg), folate as folic acid (50 mg), and Vitamin B12 as Methylcobalamin (70 mg); or, the PWS supplement with Citrus aurantium extract containing 20 mg of synephrine (PWS + S) once per day for 8-weeks during training. Participants donated a fasting blood sample and had body composition (DXA), resting heart rate and blood pressure, cognitive function (Stroop Test), readiness to perform, bench and leg press 1 RM, and Wingate anaerobic capacity assessments determined a 0, 4, and 8-weeks of standardized training. Data were analyzed by MANOVA with repeated measures. Performance and cognitive function data were analyzed using baseline values as covariates as well as mean changes from baseline with 95% confidence intervals (CI). Blood chemistry data were also analyzed using Chi-square analysis.

Results

Although significant time effects were seen, no statistically significant overall MANOVA Wilks’ Lambda interactions were observed among groups for body composition, resting heart and blood pressure, readiness to perform questions, 1RM strength, anaerobic sprint capacity, or blood chemistry panels. MANOVA univariate analysis and analysis of changes from baseline with 95% CI revealed some evidence that cognitive function and 1RM strength were increased to a greater degree in the PWS and/or PWS + S groups after 4- and/or 8-weeks compared to PLA responses. However, there was no evidence that PWS + S promoted greater overall training adaptations compared to the PWS group. Dietary supplementation of PWS and PWS + S did not increase the incidence of reported side effects or significantly affect the number of blood values above clinical norms compared to PLA.

Conclusion

Results provide some evidence that 4-weeks of PWS and/or PWS + S supplementation can improve some indices of cognitive function and exercise performance during resistance-training without significant side effects in apparently health males. However, these effects were similar to PLA responses after 8-weeks of supplementation and inclusion of synephrine did not promote additive benefits.

Trial registration

This trial (NCT02999581) was retrospectively registered on December 16th 2016.

Campbell B, Wilborn C, La Bounty P, Taylor L, Nelson MT, Greenwood M, et al. International Society of Sports Nutrition position stand: energy drinks. J Int Soc Sports Nutr. 2013;10(1):1. doi:10.1186/1550-2783-10-1.CrossRefPubMedPubMedCentral

Kreider RB, Wilborn CD, Taylor L, Campbell B, Almada AL, Collins R, et al. ISSN exercise & sport nutrition review: research & recommendations. J Int Soc Sports Nutr. 2010;7:7. doi:10.1186/1550-2783-7-7.CrossRefPubMedPubMedCentral

Kerksick C, Harvey T, Stout J, Campbell B, Wilborn C, Kreider R, et al. International Society of Sports Nutrition position stand: nutrient timing. J Int Soc Sports Nutr. 2008;5:17. doi:10.1186/1550-2783-5-17.CrossRefPubMedPubMedCentral

Eudy AE, Gordon LL, Hockaday BC, Lee DA, Lee V, Luu D, et al. Efficacy and safety of ingredients found in preworkout supplements. Am J Health Syst Pharm. 2013;70(7):577–88. doi:10.2146/ajhp120118.CrossRefPubMed

Goldstein ER, Ziegenfuss T, Kalman D, Kreider R, Campbell B, Wilborn C, et al. International society of sports nutrition position stand: caffeine and performance. J Int Soc Sports Nutr. 2010;7(1):5. doi:10.1186/1550-2783-7-5.CrossRefPubMedPubMedCentral

Trexler ET, Smith-Ryan AE, Stout JR, Hoffman JR, Wilborn CD, Sale C, et al. International society of sports nutrition position stand: Beta-Alanine. J Int Soc Sports Nutr. 2015;12:30. doi:10.1186/s12970-015-0090-y.CrossRefPubMedPubMedCentral

Buford TW, Kreider RB, Stout JR, Greenwood M, Campbell B, Spano M, et al. International Society of Sports Nutrition position stand: creatine supplementation and exercise. J Int Soc Sports Nutr. 2007;4:6. doi:10.1186/1550-2783-4-6.CrossRefPubMedPubMedCentral

Diagnostic and therapeutic technology assessment (datta). JAMA. 1992;267(2):286–94. doi:10.1001/jama.1992.03480020096040.

Bond H, Morton L, Braakhuis AJ. Dietary nitrate supplementation improves rowing performance in well-trained rowers. Int J Sport Nutr Exerc Metab. 2012;22(4):251–6.CrossRefPubMed

10.

Bond V, Curry BH, Adams RG, Asadi MS, Stancil KA, Millis RM et al. Effects of Nitrate Supplementation on Cardiovascular and Autonomic Reactivity in African-American Females. ISRN Physiol. 2014;2014. doi:10.1155/2014/676235

11.

Flanagan SD, Looney DP, Miller MJ, DuPont WH, Pryor L, Creighton BC, et al. The Effects of Nitrate-Rich Supplementation on Neuromuscular Efficiency during Heavy Resistance Exercise. J Am Coll Nutr. 2016;35(2):100–7. doi:10.1080/07315724.2015.1081572.CrossRefPubMed

12.

Campbell B, Roberts M, Kerksick C, Wilborn C, Marcello B, Taylor L, et al. Pharmacokinetics, safety, and effects on exercise performance of L-arginine alpha-ketoglutarate in trained adult men. Nutrition. 2006;22(9):872–81. doi:10.1016/j.nut.2006.06.003.CrossRefPubMed

13.

Jongkees BJ, Hommel B, Kuhn S, Colzato LS. Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands--A review. J Psychiatr Res. 2015;70:50–7. doi:10.1016/j.jpsychires.2015.08.014.CrossRefPubMed

14.

Mahoney CR, Castellani J, Kramer FM, Young A, Lieberman HR. Tyrosine supplementation mitigates working memory decrements during cold exposure. Physiol Behav. 2007;92(4):575–82. doi:10.1016/j.physbeh.2007.05.003.CrossRefPubMed

15.

Haaker J, Lonsdorf TB, Kalisch R. Effects of post-extinction l-DOPA administration on the spontaneous recovery and reinstatement of fear in a human fMRI study. Eur Neuropsychopharmacol. 2015;25(10):1544–55. doi:10.1016/j.euroneuro.2015.07.016.CrossRefPubMed

16.

Monte-Silva K, Liebetanz D, Grundey J, Paulus W, Nitsche MA. Dosage-dependent non-linear effect of L-dopa on human motor cortex plasticity. J Physiol. 2010;588(Pt 18):3415–24. doi:10.1113/jphysiol.2010.190181.CrossRefPubMedPubMedCentral

17.

Bailey SJ, Varnham RL, DiMenna FJ, Breese BC, Wylie LJ, Jones AM. Inorganic nitrate supplementation improves muscle oxygenation, O(2) uptake kinetics, and exercise tolerance at high but not low pedal rates. J Appl Physiol (1985). 2015;118(11):1396–405. doi:10.1152/japplphysiol.01141.2014.CrossRef

18.

Bloomer RJ, Farney TM, Trepanowski JF, McCarthy CG, Canale RE. Effect of betaine supplementation on plasma nitrate/nitrite in exercise-trained men. J Int Soc Sports Nutr. 2011;8:5. doi:10.1186/1550-2783-8-5.CrossRefPubMedPubMedCentral

19.

Jones AM. Dietary Nitrate Supplementation and Exercise Performance. Sports Med. 2014;44:35–45. doi:10.1007/s40279-014-0149-y.CrossRefPubMedCentral

20.

Lansley KE, Winyard PG, Bailey SJ, Vanhatalo A, Wilkerson DP, Blackwell JR, et al. Acute dietary nitrate supplementation improves cycling time trial performance. Med Sci Sports Exerc. 2011;43(6):1125–31. doi:10.1249/MSS.0b013e31821597b4.CrossRefPubMed

21.

Baguet A, Koppo K, Pottier A, Derave W. Beta-alanine supplementation reduces acidosis but not oxygen uptake response during high-intensity cycling exercise. Eur J Appl Physiol. 2010;108(3):495–503. doi:10.1007/s00421-009-1225-0.CrossRefPubMed

22.

Hoffman JR, Ratamess NA, Faigenbaum AD, Ross R, Kang J, Stout JR, et al. Short-duration beta-alanine supplementation increases training volume and reduces subjective feelings of fatigue in college football players. Nutr Res. 2008;28(1):31–5. doi:10.1016/j.nutres.2007.11.004.CrossRefPubMed

23.

Kresta JY, Oliver JM, Jagim AR, Fluckey J, Riechman S, Kelly K et al. Effects of 28 days of beta-alanine and creatine supplementation on muscle carnosine, body composition and exercise performance in recreationally active females. J Int Soc Sports Nutr. 2014;11. doi:ARTN 55, DOI 10.1186/s12970-014-0055-6.

24.

Walter AA, Smith AE, Kendall KL, Stout JR, Cramer JT. Six weeks of high-intensity interval training with and without beta-alanine supplementation for improving cardiovascular fitness in women. J Strength Cond Res. 2010;24(5):1199–207. doi:10.1519/JSC.0b013e3181d82f8b.CrossRefPubMed

25.

Stellingwerff T, Decombaz J, Harris RC, Boesch C. Optimizing human in vivo dosing and delivery of beta-alanine supplements for muscle carnosine synthesis. Amino Acids. 2012;43(1):57–65. doi:10.1007/s00726-012-1245-7.CrossRefPubMed

26.

Harris RC, Wise JA, Price KA, Kim HJ, Kim CK, Sale C. Determinants of muscle carnosine content. Amino Acids. 2012;43(1):5–12. doi:10.1007/s00726-012-1233-y.CrossRefPubMedPubMedCentral

27.

Harris RC, Tallon MJ, Dunnett M, Boobis L, Coakley J, Kim HJ, et al. The absorption of orally supplied beta-alanine and its effect on muscle carnosine synthesis in human vastus lateralis. Amino Acids. 2006;30(3):279–89. doi:10.1007/s00726-006-0299-9.CrossRefPubMed

28.

Kreider RB, Jung YP. Creatine supplementation in exercise, sport, and medicine. J Exerc Nutr Biochem. 2011;15(2):53–69.CrossRef

29.

Astell KJ, Mathai ML, Su XQ. A review on botanical species and chemical compounds with appetite suppressing properties for body weight control. Plant Foods Hum Nutr. 2013;68(3):213–21. doi:10.1007/s11130-013-0361-1.CrossRefPubMed

30.

Ratamess NA, Bush JA, Kang J, Kraemer WJ, Stohs SJ, Nocera VG et al. The Effects of Supplementation with p-Synephrine Alone and in Combination with Caffeine on Metabolic, Lipolytic, and Cardiovascular Responses during Resistance Exercise. J Am Coll Nutr. 2016:1–13. doi:10.1080/07315724.2016.1150223

31.

Ratamess NA, Bush JA, Kang J, Kraemer WJ, Stohs SJ, Nocera VG, et al. The effects of supplementation with P-Synephrine alone and in combination with caffeine on resistance exercise performance. J Int Soc Sports Nutr. 2015;12:35. doi:10.1186/s12970-015-0096-5.CrossRefPubMedPubMedCentral

32.

Gutierrez-Hellin J, Del Coso J. Acute p-synephrine ingestion increases fat oxidation rate during exercise. Br J Clin Pharmacol. 2016;82(2):362–8. doi:10.1111/bcp.12952.CrossRefPubMed

33.

Sale C, Harris RC, Delves S, Corbett J. Metabolic and physiological effects of ingesting extracts of bitter orange, green tea and guarana at rest and during treadmill walking in overweight males. Int J Obes (Lond). 2006;30(5):764–73. doi:10.1038/sj.ijo.0803209.CrossRef

34.

Gougeon R, Harrigan K, Tremblay JF, Hedrei P, Lamarche M, Morais JA. Increase in the thermic effect of food in women by adrenergic amines extracted from citrus aurantium. Obes Res. 2005;13(7):1187–94. doi:10.1038/oby.2005.141.CrossRefPubMed

35.

Haaz S, Fontaine KR, Cutter G, Limdi N, Perumean-Chaney S, Allison DB. Citrus aurantium and synephrine alkaloids in the treatment of overweight and obesity: an update. Obes Rev. 2006;7(1):79–88. doi:10.1111/j.1467-789X.2006.00195.x.CrossRefPubMed

36.

Preuss HG, DiFerdinando D, Bagchi M, Bagchi D. Citrus aurantium as a thermogenic, weight-reduction replacement for ephedra: an overview. J Med. 2002;33(1–4):247–64.PubMed

37.

Hansen DK, George NI, White GE, Pellicore LS, Abdel-Rahman A, Fabricant D, et al. Physiological effects following administration of Citrus aurantium for 28 days in rats. Toxicol Appl Pharmacol. 2012;261(3):236–47. doi:10.1016/j.taap.2012.04.006.CrossRefPubMed

38.

Penzak SR, Jann MW, Cold JA, Hon YY, Desai HD, Gurley BJ. Seville (sour) orange juice: synephrine content and cardiovascular effects in normotensive adults. J Clin Pharmacol. 2001;41(10):1059–63.CrossRefPubMed

39.

Stohs SJ, Badmaev V. A Review of Natural Stimulant and Non-stimulant Thermogenic Agents. Phytother Res. 2016;30(5):732–40. doi:10.1002/ptr.5583.CrossRefPubMedPubMedCentral

40.

Rahnama S, Rabiei Z, Alibabaei Z, Mokhtari S, Rafieian-Kopaei M, Deris F. Anti-amnesic activity of Citrus aurantium flowers extract against scopolamine-induced memory impairments in rats. Neurol Sci. 2015;36(4):553–60. doi:10.1007/s10072-014-1991-2.CrossRefPubMed

41.

Yang W, Ma J, Liu Z, Lu Y, Hu B, Yu H. Effect of naringenin on brain insulin signaling and cognitive functions in ICV-STZ induced dementia model of rats. Neurol Sci. 2014;35(5):741–51. doi:10.1007/s10072-013-1594-3.CrossRefPubMed

42.

Cho M, Jung Y, Goodenough C, O’Connor A, Dalton R, Levers K, et al. Effects of ingesting a pre-workout supplement with and without synephrine on cognitive function, perceptions of readiness to perform, and exercise performance. J Int Soc Sports Nutr. 2014;11(1):1–2. doi:10.1186/1550-2783-11-s1-p36.CrossRef

43.

Jung Y, Goodenough C, Cho M, O’Connor A, Dalton R, Levers K, et al. Thermogenic and hemodynamic effects of ingesting a pre-workout supplement with and without synephrine. J Int Soc Sports Nutr. 2014;11(1):1–2. doi:10.1186/1550-2783-11-s1-p35.CrossRef

44.

Jung YP, Koozechian M, O’Connor A, Shin S, Collins PB, Dalton R, et al. Effects Of Short-term Pre-workout Supplement Ingestion At Different Dosages On Exercise Performance: 901 Board #217 June 1, 3: 30 PM - 5: 00 PM. Med Sci Sports Exerc. 2016;48(5 Suppl 1):254. doi:10.1249/01.mss.0000485764.31303.3e.CrossRefPubMed

45.

Kerksick CM, Wilborn CD, Campbell BI, Roberts MD, Rasmussen CJ, Greenwood M, et al. Early-phase adaptations to a split-body, linear periodization resistance training program in college-aged and middle-aged men. J Strength Cond Res. 2009;23(3):962–71. doi:10.1519/JSC.0b013e3181a00baf.CrossRefPubMed

46.

Galvan E, Walker DK, Simbo SY, Dalton R, Levers K, O’Connor A, et al. Acute and chronic safety and efficacy of dose dependent creatine nitrate supplementation and exercise performance. J Int Soc Sports Nutr. 2016;13:12. doi:10.1186/s12970-016-0124-0.CrossRefPubMedPubMedCentral

47.

Jagim AR, Oliver JM, Sanchez A, Galvan E, Fluckey J, Riechman S, et al. A buffered form of creatine does not promote greater changes in muscle creatine content, body composition, or training adaptations than creatine monohydrate. J Int Soc Sports Nutr. 2012;9(1):43. doi:10.1186/1550-2783-9-43.CrossRefPubMedPubMedCentral

48.

Kreider RB, Melton C, Rasmussen CJ, Greenwood M, Lancaster S, Cantler EC, et al. Long-term creatine supplementation does not significantly affect clinical markers of health in athletes. Mol Cell Biochem. 2003;244(1–2):95–104.CrossRefPubMed

49.

Levers K, Dalton R, Galvan E, O’Connor A, Goodenough C, Simbo S, et al. Effects of powdered Montmorency tart cherry supplementation on acute endurance exercise performance in aerobically trained individuals. J Int Soc Sports Nutr. 2016;13:22. doi:10.1186/s12970-016-0133-z.CrossRefPubMedPubMedCentral

50.

Klesges RC, Ward KD, Shelton ML, Applegate WB, Cantler ED, Palmieri GM, et al. Changes in bone mineral content in male athletes. Mechanisms of action and intervention effects. JAMA. 1996;276(3):226–30.CrossRefPubMed

51.

Almada AL, Kreider RB, Ransom J, Rasmussen C, Tutko R, Milnor P, Almada AL, Kreider RB, Ransom J, Rasmussen C, Tutko R, Milnor P. Comparison of the reliability of repeated whole body DEXA scans to repeated spine and hip scans. J Bone Miner Res. 1999;14:243.

52.

Kaminsky LA, Bryant CX, Mahler DA, Durstine JL, Humphrey RH. ACSM’s Guidelines for Exercise Testing and Prescription. 8th ed. Baltimore: Lippincott, Williams & Wilkins; 2009.

53.

Golden CJ. Group version of the Stroop color and word test. J Pers Assess. 1975;39(4):386–8. doi:10.1207/s15327752jpa3904_10.CrossRefPubMed

54.

Bowling JL, Katayev A. An evaluation of the Roche Cobas c 111. Lab Med. 2010;41(7):398–402.CrossRef

55.

Page P. Beyond statistical significance: clinical interpretation of rehabilitation research literature. Int J Sports Phys Ther. 2014;9(5):726–36.PubMedPubMedCentral

56.

Kedia AW, Hofheins JE, Habowski SM, Ferrando AA, Gothard MD, Lopez HL. Effects of a pre-workout supplement on lean mass, muscular performance, subjective workout experience and biomarkers of safety. Int J Med Sci. 2014;11(2):116–26. doi:10.7150/ijms.7073.CrossRefPubMedPubMedCentral

57.

Spradley BD, Crowley KR, Tai CY, Kendall KL, Fukuda DH, Esposito EN, et al. Ingesting a pre-workout supplement containing caffeine, B-vitamins, amino acids, creatine, and beta-alanine before exercise delays fatigue while improving reaction time and muscular endurance. Nutr Metab (Lond). 2012;9:28. doi:10.1186/1743-7075-9-28.CrossRef

58.

Outlaw JJ, Wilborn CD, Smith-Ryan AE, Hayward SE, Urbina SL, Taylor LW, et al. Acute effects of a commercially-available pre-workout supplement on markers of training: a double-blind study. J Int Soc Sports Nutr. 2014;11:40. doi:10.1186/s12970-014-0040-0.CrossRefPubMedPubMedCentral

59.

Gonzalez AM, Walsh AL, Ratamess NA, Kang J, Hoffman JR. Effect of a pre-workout energy supplement on acute multi-joint resistance exercise. J Sports Sci Med. 2011;10(2):261–6.PubMedPubMedCentral

60.

Sale C, Artioli GG, Gualano B, Saunders B, Hobson RM, Harris RC. Carnosine: from exercise performance to health. Amino Acids. 2013;44(6):1477–91. doi:10.1007/s00726-013-1476-2.CrossRefPubMed

61.

Harris RC, Sale C. Beta-alanine supplementation in high-intensity exercise. Med Sport Sci. 2012;59:1–17. doi:10.1159/000342372.CrossRefPubMed

62.

Sale C, Saunders B, Harris RC. Effect of beta-alanine supplementation on muscle carnosine concentrations and exercise performance. Amino Acids. 2010;39(2):321–33. doi:10.1007/s00726-009-0443-4.CrossRefPubMed

63.

Joy JM, Lowery RP, Falcone PH, Mosman MM, Vogel RM, Carson LR, et al. 28 days of creatine nitrate supplementation is apparently safe in healthy individuals. J Int Soc Sports Nutr. 2014;11(1):60. doi:10.1186/s12970-014-0060-9.CrossRefPubMedPubMedCentral

64.

d’El-Rei J, Cunha AR, Trindade M, Neves MF. Beneficial Effects of Dietary Nitrate on Endothelial Function and Blood Pressure Levels. Int J Hypertens. 2016;2016:6791519. doi:10.1155/2016/6791519.PubMedPubMedCentral

65.

Hord NG, Tang Y, Bryan NS. Food sources of nitrates and nitrites: the physiologic context for potential health benefits. Am J Clin Nutr. 2009;90(1):1–10. doi:10.3945/ajcn.2008.27131.CrossRefPubMed

66.

Wax B, Kavazis AN, Webb HE, Brown SP. Acute L-arginine alpha ketoglutarate supplementation fails to improve muscular performance in resistance trained and untrained men. J Int Soc Sports Nutr. 2012;9(1):17. doi:10.1186/1550-2783-9-17.CrossRefPubMedPubMedCentral

67.

Willoughby DS, Boucher T, Reid J, Skelton G, Clark M. Effects of 7 days of arginine-alpha-ketoglutarate supplementation on blood flow, plasma L-arginine, nitric oxide metabolites, and asymmetric dimethyl arginine after resistance exercise. Int J Sport Nutr Exerc Metab. 2011;21(4):291–9.CrossRefPubMed

68.

Kaats GR, Miller H, Preuss HG, Stohs SJ. A 60 day double-blind, placebo-controlled safety study involving Citrus aurantium (bitter orange) extract. Food Chem Toxicol. 2013;55:358–62. doi:10.1016/j.fct.2013.01.013. S0278-6915(13)00035-5 [pii].CrossRefPubMed

69.

Smith AE, Fukuda DH, Kendall KL, Stout JR. The effects of a pre-workout supplement containing caffeine, creatine, and amino acids during three weeks of high-intensity exercise on aerobic and anaerobic performance. J Int Soc Sports Nutr. 2010;7:10. doi:10.1186/1550-2783-7-10.CrossRefPubMedPubMedCentral

70.

Lopez HL, Ziegenfuss TN, Hofheins JE, Habowski SM, Arent SM, Weir JP, et al. Eight weeks of supplementation with a multi-ingredient weight loss product enhances body composition, reduces hip and waist girth, and increases energy levels in overweight men and women. J Int Soc Sports Nutr. 2013;10(1):22. doi:10.1186/1550-2783-10-22.CrossRefPubMedPubMedCentral

71.

Greenway F, de Jonge-Levitan L, Martin C, Roberts A, Grundy I, Parker C. Dietary herbal supplements with phenylephrine for weight loss. J Med Food. 2006;9(4):572–8. doi:10.1089/jmf.2006.9.572.CrossRefPubMed

72.

Joy JM, Lowery RP, Falcone PH, Vogel RM, Mosman MM, Tai CY, et al. A multi-ingredient, pre-workout supplement is apparently safe in healthy males and females. Food Nutr Res. 2015;59:27470. doi:10.3402/fnr.v59.27470.CrossRefPubMed

73.

Lowery RP, Joy JM, Dudeck JE, Oliveira de Souza E, McCleary SA, Wells S, et al. Effects of 8 weeks of Xpand(R) 2X pre workout supplementation on skeletal muscle hypertrophy, lean body mass, and strength in resistance trained males. J Int Soc Sports Nutr. 2013;10(1):44. doi:10.1186/1550-2783-10-44.CrossRefPubMedPubMedCentral

74.

Hoffman JR, Kang J, Ratamess NA, Hoffman MW, Tranchina CP, Faigenbaum AD. Examination of a pre-exercise, high energy supplement on exercise performance. J Int Soc Sports Nutr. 2009;6:2. doi:10.1186/1550-2783-6-2.CrossRefPubMedPubMedCentral

75.

Walsh AL, Gonzalez AM, Ratamess NA, Kang J, Hoffman JR. Improved time to exhaustion following ingestion of the energy drink Amino Impact (TM). Journal of the International Society of Sports Nutrition. 2010;7. doi:Artn 14, Doi 10.1186/1550-2783-7-14.

76.

Wells AJ, Hoffman JR, Gonzalez AM, Stout JR, Fragala MS, Mangine GT, et al. Phosphatidylserine and caffeine attenuate postexercise mood disturbance and perception of fatigue in humans. Nutr Res. 2013;33(6):464–72. doi:10.1016/j.nutres.2013.03.009.CrossRefPubMed

77.

Seifert JG, Nelson A, Devonish J, Burke ER, Stohs SJ. Effect of acute administration of an herbal preparation on blood pressure and heart rate in humans. Int J Med Sci. 2011;8(3):192–7.CrossRefPubMedPubMedCentral

78.

Stohs SJ, Preuss HG, Shara M. The safety of Citrus aurantium (bitter orange) and its primary protoalkaloid p-synephrine. Phytother Res. 2011;25(10):1421–8. doi:10.1002/ptr.3490.CrossRefPubMed

Title: Effects of ingesting a pre-workout dietary supplement with and without synephrine for 8 weeks on training adaptations in resistance-trained males
Authors: Y. Peter Jung
Conrad P. Earnest
Majid Koozehchian
Minye Cho
Nick Barringer
Dillon Walker
Christopher Rasmussen
Mike Greenwood
Peter S. Murano
Richard B. Kreider
Publication date: 01-12-2017
Publisher: BioMed Central
Published in: Journal of the International Society of Sports Nutrition / Issue 1/2017
Electronic ISSN: 1550-2783
DOI: https://doi.org/10.1186/s12970-016-0158-3

At a glance: The ONWARDS insulin icodec trials

Springer Medicine

Effects of ingesting a pre-workout dietary supplement with and without synephrine for 8 weeks on training adaptations in resistance-trained males

Abstract

Background

Methods

Results

Conclusion

Trial registration

At a glance: The ONWARDS insulin icodec trials

Springer Medicine

Abstract

Background

Methods

Results

Conclusion

Trial registration

Please log in to get access to this content

Other articles of this Issue 1/2017

Effects of an amylopectin and chromium complex on the anabolic response to a suboptimal dose of whey protein

Effects of Methylsulfonylmethane (MSM) on exercise-induced oxidative stress, muscle damage, and pain following a half-marathon: a double-blind, randomized, placebo-controlled trial

Serum reference value of two potential doping candidates—myostatin and insulin-like growth factor-I in the healthy young male

International society of sports nutrition position stand: nutrient timing

Availability of a sports dietitian may lead to improved performance and recovery of NCAA division I baseball athletes

The effect of acute pomegranate extract supplementation on oxygen uptake in highly-trained cyclists during high-intensity exercise in a high altitude environment