Effects of Phosphatidic Acid Supplementation on Strength and Hypertrophic Responses to Strength Training

There are indications that phosphatidic acid (PA) supplementation is capable of enhancing gains in strength and muscle mass in response to strength training, although the literature is still incipient and controversial. The present study will adopt a randomized, double-blind, parallel group and placebo-controlled design, with the objective of evaluating the effectiveness of chronic phosphatidic acid supplementation in gaining maximum dynamic muscle strength, body composition and muscle cross-sectional area in trained adult individuals submitted to a strength training program.

About 45 men will be randomly allocated to one of the three treatments, in the proportion 1: 1: 1: PA 750mg per day, PA 375 per day, or placebo (corn starch, 750 per day), for 8 weeks. The allocation of participants to the experimental groups will be randomized using software (www.random.org). In addition to the pairing, the groups will be equalized by the maximum dynamic force (sum of the upper and lower limb loads) of the participants at the PRE moment. For randomization, proportional distribution between groups and equalization by maximum force, participants will be recruited in blocks of 6 or 9 participants, which will be ranked based on their maximum strength, with these procedures being carried out within each block. Random sequences of numbers 1, 2 and 3, representing the treatments PA high dose, PA low dose and placebo, will be randomly distributed to each three participants within each block, respecting the ranking by maximum force.

All participants will be submitted to a 8-week strength training program, 3 times a week, totaling 24 sessions, which will start at the beginning of supplementation. The training will follow the daily wavy periodization model.In this model, the weekly training sessions are called A, B and C, with the total volume changed at each session, as follows: in sessions A, participants will do 3 sets of each exercise, in sessions B, 4 sets of each exercise and, in sessions C, again 3 sets of each exercise. Participants will perform the following exercises: bench press, 45º leg-press, pulley pull, squat on the guided bar and leg extension in the extension chair. The interval between sets will be 60 seconds and, between exercises, 90 seconds. The loads will be individually adjusted for each series, in such a way that the participants are able to perform between 8 and 12 maximum repetitions (until the concentric failure or until the participant cannot maintain an adequate pattern of movement).

Before and after treatments, participants will be evaluated for the following parameters: body composition, maximum dynamic strength of upper limbs (1RM supine) and lower limbs (1RM leg-press), dynamic strength resistance of upper and lower limbs, cross-sectional area of the vastus lateralis and rectus femoris muscles via ultrasound.The following blood parameters will also be evaluated: CK, LDH, free testosterone, IGF-1, GH and cortisol through immunoenzymatic, colorimetric enzymatic or fluorimetric enzymatic assays. Additional blood collections will be performed 48 hours after the first and last sessions training for specific determination of blood muscle damage markers: CK and LDH.

The assessment of maximum strength will be performed on leg-press equipment, for the lower limbs, and supine, for the upper limbs. The tests for assessing maximum dynamic strength (1RM) will follow methods proposed by the American Society for Exercise Physiology (Brown & Weir, 2001). The evaluation of dynamic strength endurance will be performed in leg-press and bench press exercises where the volunteers must perform repetitions until fatigue with a load equivalent to 70% of 1RM, which will be previously determined in the maximum strength test. Participants will have to perform the maximum number of repetitions until reaching the concentric failure. Each individual will perform 3 sets with an interval of 2 minutes between them.