Sex Differences in Heart Rate Variability Responses to Eight Weeks of Circuit Training

NCT07856628 | Completed DMC

• 1 other identifier: USM/JEPeM/KK/25010089
• Study Type: interventional
• Target: 17
• Locations: 1 country
• Sites: 1

Brief Summary

The main goal of this study is to find out how an 8-week circuit training exercise program affects heart health and how the body recovers in young adults who do not regularly exercise. The researchers also want to see if these responses are different between men and women. The body's nervous system controls automatic functions like heart rate. Measuring changes in heart rate patterns-known as heart rate variability (HRV)-helps show how well the body switches between "fight-or-flight" (stress/exercise mode) and "rest-and-digest" (recovery mode). While men and women naturally have different heart rate patterns at rest, less is known about whether they recover differently after a structured exercise program. The main questions this study aims to answer are:

• Exercise Sessions: Each session started with a 5-minute warm-up, followed by 10 exercise stations using light weights, resistance bands, and bodyweight movements. Exercises targeted both upper and lower body muscles.
• Workouts and Rest: Participants did each exercise for 30 seconds, rested for 1 minute between stations, and rested for 5 minutes between full sets.
• Progression: During Weeks 1 to 4, participants did 2 sets per session. During Weeks 5 to 8, they increased to 3 sets per session. To measure heart rate recovery, participants wore a heart rate chest monitor while resting quietly lying down:
• Before starting the 8-week program (Baseline)
• At 10 minutes after a workout at Week 8 (Short-term recovery)
• At 24 hours after a workout at Week 8 (Full recovery)

Conditions

Physical Inactivity

Keywords

Heart rate variability; Autonomic recovery; Sex differences; Circuit training; Frequency domain; Physically inactive

Outcome Measures

Primary Outcomes (3)

• Change in Low-Frequency (LF) Power in Normalized Units (LF n.u.)

  Frequency-domain heart rate variability metric reflecting combined sympathetic and parasympathetic autonomic modulation (measured in normalized units, n.u.).

  Measured at Baseline (Week 0), Post-10 minutes (Week 8), and Post-24 hours (Week 8).

• Change in High-Frequency (HF) Power in Normalized Units (HF n.u.)

  Frequency-domain heart rate variability metric reflecting parasympathetic (vagal) autonomic modulation (measured in normalized units, n.u.)

  Measured at Baseline (Week 0), Post-10 minutes (Week 8), and Post-24 hours (Week 8).

• Change in Low-Frequency to High-Frequency Ratio (LF/HF Ratio)

  Ratio of LF power to HF power, used as an index of sympathovagal balance during recovery.

  Measured at Baseline (Week 0), Post-10 minutes (Week 8), and Post-24 hours (Week 8).

Study Arms (2)

Male Group

EXPERIMENTAL

Male participants undergoing an 8-week supervised circuit training intervention (2 sessions per week; 2 sets per session for weeks 1-4, 3 sets per session for weeks 5-8).

Behavioral: Circuit Training Program

Female Group

EXPERIMENTAL

Female participants undergoing the identical 8-week supervised circuit training intervention (2 sessions per week; 2 sets per session for weeks 1-4, 3 sets per session for weeks 5-8).

Behavioral: Circuit Training Program

Interventions

Circuit Training Program BEHAVIORAL

Participants complete an 8-week supervised circuit training intervention consisting of 20 total sessions (2 sessions per week). Each session begins with a 5-minute warm-up, followed by 10 exercise stations targeting both upper-body and lower-body muscle groups using body weight, resistance bands, and dumbbells. The 10 stations include: heel raises with dumbbells, lateral raises with resistance bands, leg abductions with resistance bands, shoulder extensions and flexions with resistance bands, jump rope, triceps extensions with dumbbells, half squats with resistance bands, standing chest fly with dumbbells, leg curls with resistance bands, and bicep curls with dumbbells. Each exercise station is performed for 30 seconds with a 1-minute rest interval between stations, and a 5-minute rest interval between complete sets. Training volume progresses from 2 sets per session in Weeks 1-4 (8 sessions) to 3 sets per session in Weeks 5-8 (12 sessions)

Also known as: Progressive Circuit Training Protocol

Female Group; Male Group

Eligibility Criteria

• Age: 18 Years - 25 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Physically inactive, defined as engaging in less than 150 minutes of moderate-intensity aerobic activity or less than 75 minutes of vigorous-intensity activity per week.
• Enrolled university student.
• Willing and able to provide informed consent and attend supervised training sessions twice per week for 8 weeks.

You may not qualify if:

• Regular engagement in structured exercise or training programs.
• Current consumption of dietary supplements.
• Inability or unwillingness to refrain from caffeine, alcohol, and vigorous physical activity for 24 hours prior to heart rate variability (HRV) testing sessions.

Sponsors & Collaborators

• Universiti Sains Malaysia: lead

Study Sites (1)

Exercise and Sports Science Laboratory, Universiti Sains Malaysia

Kubang Kerian, Kelantan, 16150, Malaysia

Location

Related Publications (6)

• Ramos-Campo DJ, Andreu Caravaca L, Martinez-Rodriguez A, Rubio-Arias JA. Effects of Resistance Circuit-Based Training on Body Composition, Strength and Cardiorespiratory Fitness: A Systematic Review and Meta-Analysis. Biology (Basel). 2021 Apr 28;10(5):377. doi: 10.3390/biology10050377.

  PMID: 33924785 BACKGROUND

• Shaffer F, Ginsberg JP. An Overview of Heart Rate Variability Metrics and Norms. Front Public Health. 2017 Sep 28;5:258. doi: 10.3389/fpubh.2017.00258. eCollection 2017.

  PMID: 29034226 BACKGROUND

• Heart rate variability: standards of measurement, physiological interpretation and clinical use. Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. Circulation. 1996 Mar 1;93(5):1043-65. No abstract available.

  PMID: 8598068 BACKGROUND

• Kappus RM, Ranadive SM, Yan H, Lane-Cordova AD, Cook MD, Sun P, Harvey IS, Wilund KR, Woods JA, Fernhall B. Sex differences in autonomic function following maximal exercise. Biol Sex Differ. 2015 Dec 1;6:28. doi: 10.1186/s13293-015-0046-6. eCollection 2015.

  PMID: 26629325 BACKGROUND

• Koenig J, Thayer JF. Sex differences in healthy human heart rate variability: A meta-analysis. Neurosci Biobehav Rev. 2016 May;64:288-310. doi: 10.1016/j.neubiorev.2016.03.007. Epub 2016 Mar 7.

  PMID: 26964804 BACKGROUND

• Ibrahim NS, Muhamad AS, Chen CK, & Ooi FK. (2022) Effects of probiotics consumption and resistance exercise on bone metabolism markers in physically inactive young males. Malays J Sport Sci Recreat 18(1), 92. https://doi.org/10.24191/mjssr.v18i1.17643

  BACKGROUND

MeSH Terms

Conditions

Sedentary Behavior

Condition Hierarchy (Ancestors)

Behavior

Study Officials

• Marilyn Li Yin Ong, PhD

  Universiti Sains Malaysia

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Dr

Model Details: The study uses a two-arm non-randomized parallel design comparing male and female cohorts. Participants are assigned to their respective arm based on biologically determined sex (male vs. female). Both groups receive the identical supervised 8-week progressive circuit training intervention (2 sessions per week; 2 sets in weeks 1-4, 3 sets in weeks 5-8) and undergo identical heart rate variability (HRV) evaluations at baseline, 10 minutes post-training, and 24 hours post-training.

Study Record Dates

• First Submitted: September 28, 2026
• First Posted: October 2, 2026
• Study Start: March 6, 2025
• Primary Completion: March 5, 2026
• Study Completion: March 5, 2026
• Last Updated: October 2, 2026

Record last verified: 2026-09

Data Sharing

• IPD Sharing: Will not share

Locations

MY (1)