title: The effects of supplementation with P-Synephrine alone and in combination with caffeine on resistance exercise performance.
abstract: BACKGROUND
  Little is known concerning the potential ergogenic effects of p-synephrine supplementation. Therefore, the purpose of the present study was to examine the effects of supplementation with p-synephrine alone and in combination with caffeine on free-weight resistance exercise performance.
  
  
  METHODS
  Twelve healthy, college-aged men performed a control (CT) resistance exercise protocol consisting of 6 sets of squats for up to 10 repetitions per set using 80% of their one repetition-maximum (1RM) with 2 min of rest in between sets. Each subject was randomly assigned (in double-blind, balanced manner) to a treatment sequence consisting of use of 3 supplements: p-synephrine (S; 100 mg), p-synephrine + caffeine (SCF; 100 mg of p-synephrine plus 100 mg of caffeine), or a placebo (P). For each supplement treatment (separated by 1 week), subjects consumed the supplement for 3 days prior to each protocol and the morning of each protocol, and subsequently did not consume any supplements for 3 days following (i.e. wash-out period). On each protocol day, subjects reported to the lab at a standard time, consumed a supplement, sat quietly for 45 min, performed the resistance exercise protocol, and sat quietly for 30 min post exercise. Performance (repetition number, force, velocity and power), blood lactate, and ratings of perceived exertion (RPE) data were collected during each protocol.
  
  
  RESULTS
  Supplements SCF and S produced a significantly (P < 0.05) greater number of repetitions performed than CT (by 11.0 ± 8.0%) and P (by 6.0 ± 7.0%) and a 10.6 ± 12.0% greater increase in volume load per protocol than CT and P. Most of the differences were seen during the last 3 sets. Mean power and velocity for all 6 sets were significantly higher in SCF compared to CT and P by ~6.2 ± 8.0%. No supplement effects were observed in RPE or blood lactate, and no adverse side effects were observed or reported.
  
  
  CONCLUSIONS
  S and SCF augmented resistance exercise performance (total repetitions, volume load) without increasing blood lactate or RPE. The addition of caffeine in SCF increased mean power and velocity of squat performance. These results indicate supplementation with S and SCF can enhance local muscle endurance during resistance exercise.
authors.affiliation: Department of Health and Exercise Science, The College of New Jersey, Ewing, NJ 08628 USA.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Ratamess
authors.affiliation: Department of Health and Exercise Science, The College of New Jersey, Ewing, NJ 08628 USA.
authors.forename: Jill A
authors.initials: JA
authors.lastname: Bush
authors.affiliation: Department of Health and Exercise Science, The College of New Jersey, Ewing, NJ 08628 USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Kang
authors.affiliation: Department of Human Sciences, The Ohio State University, Columbus, OH 43210 USA.
authors.forename: William J
authors.initials: WJ
authors.lastname: Kraemer
authors.affiliation: School of Pharmacy and Health Professions, Creighton University, Omaha, NE 68178 USA.
authors.forename: Sidney J
authors.initials: SJ
authors.lastname: Stohs
authors.affiliation: Department of Health and Exercise Science, The College of New Jersey, Ewing, NJ 08628 USA.
authors.forename: Vincenzo G
authors.initials: VG
authors.lastname: Nocera
authors.affiliation: Department of Health and Exercise Science, The College of New Jersey, Ewing, NJ 08628 USA.
authors.forename: Megan D
authors.initials: MD
authors.lastname: Leise
authors.affiliation: Department of Health and Exercise Science, The College of New Jersey, Ewing, NJ 08628 USA.
authors.forename: Keith B
authors.initials: KB
authors.lastname: Diamond
authors.affiliation: Department of Health and Exercise Science, The College of New Jersey, Ewing, NJ 08628 USA.
authors.forename: Avery D
authors.initials: AD
authors.lastname: Faigenbaum
mesh_terms: D054874:Athletic Performance; D002110:Caffeine / Q000008:administration & dosage / Q000494:pharmacology*; D019587:Dietary Supplements; D004311:Double-Blind Method; D006801:Humans; D007537:Isometric Contraction / Q000187:drug effects* / Q000502:physiology; D008297:Male; D053580:Muscle Strength / Q000187:drug effects* / Q000502:physiology; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000502:physiology; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000187:drug effects* / Q000502:physiology; D055070:Resistance Training; D013578:Synephrine / Q000008:administration & dosage / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D002110:Caffeine; D013578:Synephrine