Effects of a 5-Week Probiotic Supplementation Intervention on Markers of Delayed Onset Muscle Soreness

The purpose of this study is to evaluate how probiotic supplementation (PS) influences post-exercise recovery in healthy, physically active young adults. Researchers aim to determine if the Lactobacillus casei probiotic strain reduces symptoms of delayed onset muscle soreness (DOMS) based on perceived muscle soreness, pressure pain threshold, and power output following exercise induced muscle damage (EIMD).

Study Overview

• Status: Recruiting
• Conditions: Exercise Induced Muscle Damage; Delayed Onset Muscle Soreness (DOMS)
• Intervention / Treatment: Dietary supplement: Lactobacillus casei; Other: Placebo Capsule(s)

• Study Type: Interventional
• Enrollment (Estimated): 24
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Jakob Fischer; Phone Number: 507-236-8051; Email: fisc0887@d.umn.edu

Study Locations

• United States
  • Minnesota
    • Minneapolis, Minnesota, United States, 55455
      • Recruiting
      • University of Minnesota
      • Contact: Jakob Fischer; Phone Number: 507-236-8051; Email: fisc0887@d.umn.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• complete a minimum of 150 minutes a week of at least moderate intensity exercise in either an endurance-based or resistance-based training style based on a self-reported physical activity over the past month
• good general health with no injuries or health conditions that would affect physical activity
• willing to abstain from consistent NSAID use and other probiotic supplements over the course of this study

Exclusion Criteria:

• known musculoskeletal injuries or physical limitations that could interfere with performing the designated physical activity required
• underlying conditions that could place them at an increased risk during exercise such as cardiovascular, respiratory, or metabolic diseases
• currently take a probiotic supplement, are prescribed and taking an antibiotic during the intervention, or report using NSAIDs or steroids within the recovery time window
• report using an NSAID more than twice a week on a regular basis

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: Placebo Group	Other: Placebo Capsule(s); The brand name of placebo capsules that will be used in this study is Magic Bullet Placebo Capsules. This placebo is manufactured by Progressive Placebo as stated on the product label.
Active Comparator: Probiotic Group	Dietary supplement: Lactobacillus casei; Probiohealth is the manufacturer of this strain and they use a stringent quality control program that utilizes a multi point product variability check system.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in perceived muscle soreness	Visual Analog Scale for perceived muscle soreness Each number on the scale will be designated with a descriptive word that corresponds to the soreness level they are experiencing. The scale will be laid out in order of increasing muscle soreness with "1" representing no pain.	From baseline to post 5-week intervention
Change in pressure pain threshold (PPT)	Calf pressure pain threshold (PPT) will be assessed by placing marks on the medial condyle of the femur and the posterior of the medial malleolus. The researcher will place the algometer on the muscle belly exactly halfway between the two marks. Volunteers will be instructed to specify when the first onset of pain occurs as the researcher gradually applies pressure. Quadricep measurements will involve the participant lying in the supine position where marks will be made on the anterior inferior iliac spine and the top of the patella so the researchers can once again find a point exactly halfway between these two locations to apply the algometer. Participants will be instructed to verbally indicate to the researcher when the onset of pain occurs as pressure is applied.	From baseline to post 5-week intervention
Change in countermovement jump assessment (CMJ) performance recovery	The researchers will demonstrate and instruct volunteers to "Stand upright with their hands above their head. When you are ready, bend your knees and stick your hips back while keeping your hands to your hips. Jump as high as possible and land softly." Participants will perform three CMJs separated by 60 seconds. Jump height will be recorded in cm and the highest value will be recorded.	From baseline to post 5-week intervention

Collaborators and Investigators

• Sponsor: University of Minnesota
• Investigators: Principal Investigator: Mary Stenson, University of Minnesota

Study record dates

Study Major Dates

• Study Start (Actual): February 5, 2026
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: October 17, 2025
• First Submitted That Met QC Criteria: October 17, 2025
• First Posted (Actual): October 22, 2025

Study Record Updates

• Last Update Posted (Actual): May 4, 2026
• Last Update Submitted That Met QC Criteria: April 30, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: Probiotic Supplementation

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No