Effects of CrossFit Training on the Immune System (CFIT-IMMUNE)

September 11, 2026 updated by: Assoc. Prof. Dr. Özgür EKEN, Inonu University

From Acute Response to Chronic Adaptation: Immunological Effects of an Eight-Week CrossFit Training Program in Sedentary Adults

This interventional study aims to investigate the effects of both acute and eight-week CrossFit training on immune system responses in sedentary adults. Participants will undergo an acute CrossFit exercise session, followed by an eight-week supervised CrossFit training program. Blood samples will be collected before and after the acute exercise session and again following the eight-week intervention to evaluate changes in selected immune system biomarkers. The primary objective is to determine whether acute and chronic CrossFit training induces significant alterations in immune function in previously sedentary individuals. The findings are expected to contribute to a better understanding of the immunological adaptations associated with high-intensity functional training and to provide evidence regarding the safety and potential health benefits of CrossFit exercise in sedentary populations.

Study Overview

Status

Completed

Detailed Description

CrossFit is a high-intensity functional training (HIFT) program that combines aerobic exercise, resistance training, weightlifting, gymnastics, and metabolic conditioning within a single exercise session. Owing to its increasing popularity among both athletes and the general population, there is growing interest in understanding the physiological and immunological adaptations associated with CrossFit training. Although regular physical activity is known to enhance immune function and improve overall health, high-intensity exercise may induce transient alterations in immune responses, particularly in previously sedentary individuals.

The immune system plays a critical role in protecting the body against infections and maintaining physiological homeostasis. Acute bouts of strenuous exercise may temporarily modify immune cell function and inflammatory responses, whereas long-term exercise training may promote beneficial adaptations and improve immune regulation. However, the effects of CrossFit training on immune system biomarkers in sedentary adults remain insufficiently investigated.

The purpose of this interventional study is to evaluate the effects of both an acute CrossFit exercise session and an eight-week supervised CrossFit training program on immune system responses in sedentary adults. Participants will complete baseline assessments followed by an acute CrossFit exercise session. Subsequently, they will participate in an eight-week supervised CrossFit training program. Blood samples will be collected at predetermined time points before and after the acute exercise session and following completion of the eight-week intervention to assess changes in immune system biomarkers.

The primary objective is to determine whether acute and chronic CrossFit training produce significant changes in immune function in sedentary individuals. The results of this study are expected to improve understanding of the immunological responses to high-intensity functional training and provide evidence regarding the safety and potential health benefits of CrossFit exercise for previously sedentary adults.

Study Type

Interventional

Enrollment (Actual)

30

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

    • Karabük Province
      • Karabük, Karabük Province, Turkey (Türkiye)
        • Exercise Physiology Laboratory, Faculty of Sport Sciences, Karabuk University

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:- Male participants aged 18 to 23 years

  • Currently enrolled as a student at Yalova University
  • Not regularly participating in exercise or sports training
  • Medically eligible to participate in CrossFit training
  • Willing and able to complete the eight-week CrossFit training program conducted three days per week
  • Willing to provide venous blood samples at the specified assessment times
  • Willing to provide written informed consent

Exclusion Criteria:- Regular participation in exercise or sports training

  • History of a neurological disorder within the previous year
  • History of an auditory, visual, or vestibular disorder within the previous year
  • Serious upper- or lower-extremity injury within the previous six months
  • Presence of a medical condition that could prevent safe participation in the exercise program
  • Inability to complete the training or blood-sampling procedures
  • Withdrawal of voluntary consent

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: CrossFit Training
Participants assigned to the CrossFit Training Group will participate in a structured CrossFit exercise program for 8 weeks. Training sessions will be performed three times per week under the supervision of certified trainers. Each session will include warm-up, functional strength exercises, high-intensity metabolic conditioning exercises, and cool-down periods. Exercise intensity will be monitored throughout the intervention period.

articipants in the experimental group will participate in an eight-week CrossFit training program performed three days per week (Monday, Wednesday, and Friday). Each training session will last approximately 60 minutes and will include a dynamic warm-up, strength training exercises, a Workout of the Day (WOD) section, and a cool-down period.

The strength training component will include functional resistance exercises such as squats, deadlifts, and push presses, performed for 3-5 sets of 5-10 repetitions. Training intensity will progressively increase from approximately 60-70% of one-repetition maximum (1RM) during the first four weeks to 70-80% of 1RM during the final four weeks.

The WOD component will include high-intensity functional exercises such as burpees, kettlebell swings, box jumps, rowing, sit-ups, pull-ups, and short-distance running. WOD sessions will be performed using AMRAP (As Many Rounds As Possible) and For Time formats with durations of approximately 10-20 minutes. P

Other Names:
  • 8-Week CrossFit Training Program

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Mean Change in Total Leukocyte Count From Baseline to Completion of the Eight-Week CrossFit Program
Time Frame: Baseline and immediately after completion of the eight-week CrossFit training program
Total leukocyte count will be determined from venous blood samples collected before the first training session and immediately after completion of the eight-week CrossFit training program. For each participant, the change will be calculated as the post-program value minus the baseline value. The group-level outcome will be summarized using the mean change and standard deviation.
Baseline and immediately after completion of the eight-week CrossFit training program
Mean Change in Absolute Monocyte Count From Baseline to Completion of the Eight-Week CrossFit Program
Time Frame: Baseline and immediately after completion of the eight-week CrossFit training program
Absolute monocyte count will be determined from venous blood samples collected before the first training session and immediately after completion of the eight-week CrossFit training program. For each participant, the change will be calculated as the post-program value minus the baseline value. The group-level outcome will be summarized using the mean change and standard deviation.
Baseline and immediately after completion of the eight-week CrossFit training program
Mean Change in Absolute Lymphocyte Count From Baseline to Completion of the Eight-Week CrossFit Program
Time Frame: Baseline and immediately after completion of the eight-week CrossFit training program
Absolute lymphocyte count will be determined from venous blood samples collected before the first training session and immediately after completion of the eight-week CrossFit training program. For each participant, the change will be calculated as the post-program value minus the baseline value. The group-level outcome will be summarized using the mean change and standard deviation.
Baseline and immediately after completion of the eight-week CrossFit training program
Mean Change in Absolute Neutrophil Count From Baseline to Completion of the Eight-Week CrossFit Program
Time Frame: Baseline and immediately after completion of the eight-week CrossFit training program
Absolute neutrophil count will be determined from venous blood samples collected before the first training session and immediately after completion of the eight-week CrossFit training program. For each participant, the change will be calculated as the post-program value minus the baseline value. The group-level outcome will be summarized using the mean change and standard deviation.
Baseline and immediately after completion of the eight-week CrossFit training program

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

May 5, 2026

Primary Completion (Actual)

June 30, 2026

Study Completion (Actual)

June 30, 2026

Study Registration Dates

First Submitted

July 28, 2026

First Submitted That Met QC Criteria

September 11, 2026

First Posted (Actual)

September 17, 2026

Study Record Updates

Last Update Posted (Actual)

September 17, 2026

Last Update Submitted That Met QC Criteria

September 11, 2026

Last Verified

September 1, 2026

More Information

Terms related to this study

Other Study ID Numbers

  • KBU-FTB12-2026-002

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

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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