The Effects of Supplementation with p-Synephrine Alone and in Combination with Caffeine on Metabolic, Lipolytic, and Cardiovascular Responses during Resistance Exercise.

OBJECTIVE: The purpose of this study was to examine the metabolic, lipolytic, and cardiovascular responses to supplementation with p-synephrine alone and in combination with caffeine during resistance exercise (RE). METHODS: Twelve healthy men performed a control RE protocol (6 × 10 repetitions of squats) and were randomly assigned (using a double-blind crossover design with random protocol sequencing) to a supplement sequence: p-synephrine (S; 100 mg), p-synephrine + caffeine (SCF; 100 mg of p-synephrine plus 100 mg of caffeine), or a placebo (P). Subjects reported to the lab at a standard time, consumed a supplement, sat quietly for 45 minutes, performed the RE protocol, and sat quietly for 30 minutes. Blood samples were collected at rest (T1), after sitting quietly for 45 minutes (T2), immediately following RE (T3), and 15 minutes (T4) and 30 minutes (T5) postexercise. Oxygen consumption (VO2) and heart rate (HR) data were collected throughout. RESULTS: Serum glycerol was significantly elevated at T2 only in S and SCF and T3 to T5 in all treatments. Nonesterified fatty acid (NEFA) concentrations did not differ between treatments. Plasma glucose was significantly elevated compared to T1 with highest area under the curve values seen in SCF. Mean VO2 and energy expenditure (EE) were significantly higher in S and SCF through 30 minutes postexercise. Fat oxidation rates favored S and SCF between 25 and 30 minutes postexercise. Mean HR during RE was significantly highest in SCF. CONCLUSIONS: Supplementation with S and SCF increases lipolysis primarily at rest and increases VO2, EE, and fat oxidation rates 30 minutes following RE. No HR changes were observed unless caffeine was added.

The effects of supplementation with P-Synephrine alone and in combination with caffeine on resistance exercise performance.

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.