Immune and Recovery Modulating Impact of Probiotic Supplementation After Intense Resistance Exercise

This study proposal seeks to examine the efficacy of probiotic supplementation at mitigating changes in immune function and recovery after completion of intense, stressful exercise while also allowing for a better understanding of its ability to promote recovery and maintenance of physical performance.

Study Visit 1 - Familiarization: During the familiarization visit, participants will first read and sign an IRB-approved informed consent document and complete a short form of the International Physical Activity Questionnaire (IPAQ). Participants will then have their height, weight, and body composition determined using Dual-Energy X-ray Absorptiometry (DEXA) (Hologic Discovery A). To standardize body composition assessment, participants will be required to observe an 8-hour fast and maintain a well-hydrated state. Each participant will provide a urine sample to confirm a hydrated stated through determination of a urine specific gravity values greater 1.020. Participants will then complete a peak oxygen consumption test (VO2Peak) using indirect calorimetry on a ParvoMedics TrueOne (Sandy, UT) metabolic cart interfaced to a motorized cycle ergometer (Lode Corival). The peak oxygen consumption test protocol will require each study participants to start at 100 watts before progressively increasing by 1 watt every two seconds. To determine whether maximal effort occurred a respiratory exchange ratio of \>1.00 must be achieved. Following the peak oxygen consumption assessment, participants will perform practice repetitions of all performance tests (force plate vertical jumps, isometric mid-thigh pulls, Biodex isometric and isokinetic knee extensor testing) as well as the exercises that will be performed during Visit 3 (leg press, hex bar deadlift, and drop jump). Study Visit 2 - Pre-Supplementation Baseline Testing: Study participants will be asked to complete a 24-hour food recall between each testing condition and will be asked to replicate their diet prior to this visit for all subsequent visits. Upon arrival, participants will first have their blood drawn from a forearm vein before completing a perceived soreness, pressure-pain threshold, and recovery assessment. Prior to testing, participants will complete the same standardized warm-up consisting of 5 minutes of light cycling, 10 body weight squats, 10 body weight walking lunges, 10 dynamic walking hamstring stretches (straight-leg march), and 10 dynamic walking quadriceps stretches. After the warm-up, participants will complete five countermovement jump squats on top of bilateral triaxial force plates (Hawkins Dynamics) interfaced to a personal computer to derive relevant force-time variables. Next, participants will complete two assessments of peak isometric force production. Using an electronic load cell with a 5,000-N capacity (Load Star load cells) connected to a computer, three 5-second maximal isometric mid-thigh pulls will be completed. Participants will then be outfitted on a Biodex isokinetic dynamometer where they will complete three maximal isometric knee extensions. Following the isometric knee extensor testing, participants will complete a 50-repetition test of concentric-only repetitions to assess changes in force production, torque, and rates of fatigue development. After the baseline performance testing, participants will have their leg press and hex bar deadlift one-repetition maximum (1RM) determined. \*Supplementation (14 days, described below) followed by exercise trial.\* Study Visit 3 (Post-Supplementation Testing, Exercise Trial): Upon arrival, study participants will be asked to complete a 24-hour food recall and between each testing condition, study participants will be asked to replicate their diet. Upon arrival, participants will first have their blood drawn from a forearm vein before completing perceived soreness, pressure-pain threshold, and recovery assessments. Prior to testing, participants will complete the same standardized warm-up consisting of 5 minutes of light cycling, 10 body weight squats, 10 body weight walking lunges, 10 dynamic walking hamstring stretches (straight-leg march), and 10 dynamic walking quadriceps stretches. After the warm-up, participants will complete five countermovement jump squats on top of bilateral triaxial force plates (Hawkins Dynamics) interfaced to a personal computer to derive relevant force-time variables. Using an electronic load cell with a 5,000-N capacity (Load Star load cells) connected to a computer, three 5-second maximal isometric mid-thigh pulls will be completed. Participants will then be positioned on a Biodex isokinetic dynamometer where they will complete three maximal isometric knee extensions. Lastly, participants will complete a 50-repetition test of concentric-only repetitions to assess changes in force production, torque, and rates of fatigue development. Following the completion of these tests, participants will perform an exercise trial according to the methods described below. Following completion of the exercise trial, participants will undergo the previous testing battery (blood sample, perceived soreness, pressure-pain threshold assessment, recovery assessment, countermovement vertical jumps, isometric mid-thigh pulls, Biodex isometric and isokinetic testing) at five time points: immediately after exercise, 30 minutes post-exercise, 1 hour, 2 hours, and 5 hours post-exercise. Study Visits 4 - 6: Post-Exercise Performance In an identical fashion, with the exception of 1RM assessment, study visits 4, 5, and 6 will be completed 24, 48, and 72 hours, respectively, after completion of the exercise bout. Briefly, study participants will return to the laboratory after an overnight fast (10 hours). Participants will bring in the completed 24-hour dietary recall, donate venous blood samples, assess their soreness, pressure-pain threshold, and recovery, complete the warm-up, perform five countermovement jumps, assess peak isometric force production, and complete a 50-repetition muscle fatigue test during each visit.