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NCT Number: NCT07418619

Minimum Effective Exercise Intensity in Sedentary Individuals

The aim of this randomized controlled intervention study is to examine the minimum exercise intensity that has an effect on cardiorespiratory fitness and/or cardiometabolic risk factors in sedentary adults. In addition, the study seeks to examine which background factors explain individual differences in exercise responses.

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Key information

Conditions

Sedentary Individuals Not Participating in Regular Exercise Training/Physical Activity Behavior Motor Activity

Age range

30 year–55 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

UKK institute for Health Promotion Research, Tampere, Pirkanmaa, Finland

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About this study

The study consists of a 2-week baseline period followed by two 6-week intervention periods. The study will compare changes in the predefined outcome variables between the exercise intervention groups and the control group that does not perform any exercise training. In addition to intensity prescribed relative to oxygen uptake reserve, exercise intensity will be retrospectively analyzed in relation to the first ventilatory threshold in order to examine the lowest effective intensity using this method as well. Among background factors, possible modifiers assumed on the basis of previous literature, will be analyzed to assess their contribution to inter-individual differences in the outcome responses. Potential main contributors are considered to be sex, the basal value of the outcome, nutritional habits, physical activity and stationary behavior outside the prescribed training, and non-invasive indicators of stress.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 30-50-year old males and females
  • Sedentary, not participating in regular exercise training/physical activity

Exclusion criteria

  • Cardiovascular symptoms/diseases
  • Musculoskeletal symptoms/diseases
  • Metabolic diseases
  • Resting blood pressure > 160/100 mmHg
  • Body mass index ≥ 35

Treatment and study plan

Exercise

Other

6 weeks of 3 x 30 min/week supervised cycle ergometer training and 6 weeks of 3 x 40-50 min/week supervised cycle ergometer training

Primary outcomes

  1. Maximal oxygen consumption

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    Assessed with step-ramp-step protocol

  2. Ventilatory thresholds

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    Assessed with step-ramp-step protocol

Secondary outcomes

  1. Pmax

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    Maximum power of the ramp cycle ergometer test

  2. Concentration of LDL cholesterol

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    Fasting state blood sample

  3. Concentration of HDL cholesterol

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    Fasting state blood sample

  4. Concentration of total cholesterol

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    Fasting state blood sample

  5. Concentration of triglycerides

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    Fasting state blood sample

  6. Concentration of blood glucose

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    Fasting state blood sample

  7. Concentration of insulin

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    Fasting state blood sample

  8. HOMA-IR

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    (Insulin × Glucose) / 22.5

  9. HbA1c

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    Fasting state blood sample

  10. Blood pressure

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    Systolic and diastolic blood pressure

  11. Resting heart rate

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    In sitting position

  12. Resting heart rate variability

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    Root mean square of successive differences in sitting position

  13. Gross efficiency

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    Gross efficiency during standard load

  14. Body weight

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    Measured using an electronic scale.

  15. Waist circumference

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

Other outcomes

  1. Body fat percentage

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    Assessed with bioimpedance

  2. Healthy diet index

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    0-100, higher score means a better outcome.

  3. NEO-FFI

    Time frame: Pre (week 0)

    Psychological personality inventory

  4. FIMS

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    Finnish version of Brunel Mood Scale; It includes 24 items divided into 6 factors: tension, depression, anger, vigour, fatigue, confusion. Each factor has scale from 0 to 16, higher score meaning worse outcome. In addition total mood disturbance = summing the five negative mood dimensions and subtracting vigour. Score can be between -16 and 84 with higher score meaning worse outcome.

  5. CD-RISC-25

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    The 25-item Connor-Davidson Resilience Scale: scoring from 0 to 100, where the higher score means better outcome.

  6. Estimated cardiorespiratory fitness

    Time frame: Pre (screening phase)

    Ekblom-Bak test

  7. Self-estimated fitness and health

    Time frame: Pre (week 0), mid (after 6 weeks), post (after 12 weeks)

    One item self-estimated fitness in 1-5 scale where higher score means worse outcome; one item self-estimated health in 1-5 scale where higher score means worse outcome.

  8. Non-exercise fitness test

    Time frame: Pre (screening phase)

    Jackson N-eX

  9. Physical/stationary behavior

    Time frame: Weekly averages throughout the study (Baseline + weeks 1-12)

    Measured with an accelerometer 24/7. Physical activity will be distributed into intensity domains according to 1) ACSM 2025 description, and 2) ventilatory thresholds. Stationary behavior will be distributed into sitting, standing and lying.

  10. Exercise heart rate

    Time frame: Throughout the study (weeks 1-12)

    Heart rate during intervention exercise

  11. Rating of perceived exertion

    Time frame: Throughout the study (weeks 1-12)

    Estimation of perceived exertion during (6-20) and after (0-10) intervention exercises

  12. Exercise heart rate variability

    Time frame: Week 1, week 6, week 7, week 12

    Heart rate variability response to intervention exercise and during 5-min recovery phase

  13. Exercise blood lactate

    Time frame: Week 1, week 6, week 7, week 12

    Blood lactate response to intervention exercise

  14. Exercise motivation

    Time frame: Week 1, week 6, week 7, week 12

    Exercise motivation in a 3-item scale based on Eccles' expectancy-value theory with a total score from 3 to 15, where higher score means better outcome

  15. State of alertness during exercise

    Time frame: Week 1, week 6, week 7, week 12

    State of alertness from a scale 1 (low alertness, relaxed) to 6 (high alertness, aroused)

  16. Affective responses to exercise

    Time frame: Week 1, week 6, week 7, week 12

    Feeling scale from -5 to 5 with higher value meaning more positive affective response

Study contacts

Contact information is provided by the study sponsor or research team.

Olli-Pekka S Nuuttila, PhD

CONTACT

[email protected]

+358505946170

Sponsors and collaborators

Lead sponsor

UKK Institute

Other

Collaborators

  • Juho Vainion säätiö
  • Paavo Nurmi Center & Unit for Health and Physical Activity

Registry information

Official study title

Minimum Effective Exercise Intensity for Improving Cardiorespiratory Fitness and Cardiometabolic Health in Sedentary Individuals

Acronym: MEI

Important dates

Study start
2026
Primary completion
2026
Study completion
2026
First posted
Feb 18, 2026
Registry last updated
Feb 18, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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