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Completed

NCT Number: NCT07785778

Cluster Training in Female Volleyball Players

This study compares the effects of three different resistance training methods-traditional training, standard cluster training, and undulating cluster training-on strength, hormonal responses, and inflammation in female volleyball players aged 18-30 years. Thirty participants with at least two years of volleyball and resistance training experience were randomly assigned to one of three groups. All participants performed resistance training three times per week and volleyball-specific training two times per week for eight weeks. Blood samples were taken before and after the first session (acute response) and after eight weeks (chronic adaptation) to measure testosterone, cortisol, IGF-1, progesterone, and C-reactive protein (CRP). Performance tests included upper-body and lower-body strength (bench press and squat), speed, agility, and vertical jump. The main finding was that undulating cluster training produced significantly greater improvements in upper-body strength compared to standard cluster training, while all three methods were equally effective for lower-body strength and other performance measures. No significant differences were found between groups for hormonal or inflammatory changes. The study provides practical guidance for coaches seeking to optimize upper-body strength gains in female volleyball players.

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Key information

Conditions

Athletic Performance Resistance Training Volleyball Players

Age range

18 year–30 year

Sex eligibility

Female

Study type

Interventional

Phase

Not applicable

Primary location

Faculty of Sport Sciences, University of Birjand

Birjand, South Khorasan Province, 9717434765, Iran

About this study

This study compares the effects of three different resistance training methods-traditional training, standard cluster training, and undulating cluster training-on strength, hormonal responses, and inflammation in female volleyball players aged 18-30 years. Thirty participants with at least two years of volleyball and resistance training experience were randomly assigned to one of three groups. All participants performed resistance training three times per week and volleyball-specific training two times per week for eight weeks. Blood samples were taken before and after the first session (acute response) and after eight weeks (chronic adaptation) to measure testosterone, cortisol, IGF-1, progesterone, and C-reactive protein (CRP). Performance tests included upper-body and lower-body strength (bench press and squat), speed, agility, and vertical jump. The main finding was that undulating cluster training produced significantly greater improvements in upper-body strength compared to standard cluster training, while all three methods were equally effective for lower-body strength and other performance measures. No significant differences were found between groups for hormonal or inflammatory changes. The study provides practical guidance for coaches seeking to optimize upper-body strength gains in female volleyball players.

Who can participate

Healthy volunteers accepted: Yes

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

Inclusion criteria

  • Female volleyball players aged 18 to 30 years

At least 2 years of continuous training in volleyball and resistance training

Complete health status (based on health and wellness questionnaire results)

No anterior cruciate ligament injury or other upper-/lower-extremity injuries in the past 6 months

Familiarity with basic resistance training techniques

Non-pregnant, with regular menstrual cycles

No regular use of medications (including oral contraceptives)

No use of ergogenic supplements affecting muscle mass (e.g., anabolic steroids, growth hormone, or insulin-like substances) in the 6 months prior to the study

Exclusion criteria

  • Absence from more than three consecutive training sessions

Any musculoskeletal injury that prevented continuation of the training program

Treatment and study plan

Traditional Resistance Training

Behavioral

Eight weeks of traditional resistance training, 3 sessions per week. Each session includes 8 exercises: dumbbell thruster, power clean, back squat, deadlift, knee flexion curl, bench press, military p

Standard Cluster Resistance Training

Behavioral

Eight weeks of standard cluster resistance training, 3 sessions per week. Same exercises and intensity progression as TRT, but with intra-set rest intervals (10-30 seconds between clusters) to maintain movement quality, repetition velocity, and power output across multiple sets.

Undulating Cluster Resistance Training

Behavioral

Eight weeks of undulating cluster resistance training, 3 sessions per week. Combines intra-set rest intervals (10-30 seconds between clusters) with systematic weekly variations in load and repetition schemes. Intensity and volume undulate across weeks to balance neural drive and load tolerance while preserving high-quality repetitions.

Primary outcomes

  1. Change in Relative Peak Power

    Time frame: baseline and after 8- week

    Relative peak power derived from the CMJ height and body mass, calculated using the Sayers equation: Peak power (W) = 60.7 × jump height (cm) + 45.3 × body mass (kg) - 2055.

Secondary outcomes

  1. Change in Lower-Body Strength (Squat 1-RM)

    Time frame: Baseline and 8 weeks

    Maximum dynamic strength of the lower body, measured using the estimated 1-repetition maximum (1-RM) test for the squat exercise. The 1-RM was estimated using the Brzycki formula based on the maximum weight participants could lift for 1-9 repetitions.

  2. Change in Speed (20-m Sprint)

    Time frame: baseline and after 8- week

    Sprint performance measured over a distance of 20 meters. Participants performed a maximal sprint, and the time was recorded in seconds.

  3. Change in Agility

    Time frame: baseline and after 8- week

    Agility performance measured using a standard agility test (e.g., T-test or similar). Participants performed the test, and the completion time was recorded in seconds.

  4. Change in Countermovement Jump (CMJ) Height

    Time frame: baseline and after 8- week

    Vertical jump height measured using a countermovement jump (CMJ) test. Participants performed 3 maximal jumps with 30-second rest intervals. The highest jump height (in centimeters) was recorded using a wall-mounted graduated tape. Peak power was then calculated using the Sayers equation.

  5. Change in Relative Peak Power

    Time frame: baseline and after 8- week

    Relative peak power derived from the CMJ height and body mass, calculated using the Sayers equation: Peak power (W) = 60.7 × jump height (cm) + 45.3 × body mass (kg) - 2055.

  6. Change in Serum Testosterone

    Time frame: Baseline, immediately after the first session, and 48 hours after the last session (week 8)

    Serum levels of testosterone measured using commercial chemiluminescence immunoassay kits. Samples were collected before and after the first session (acute) and after eight weeks (chronic).

  7. Change in Serum Cortisol

    Time frame: Baseline, immediately after the first session, and 48 hours after the last session (week 8)

    Serum levels of cortisol measured using commercial chemiluminescence immunoassay kits. Samples were collected before and after the first session (acute) and after eight weeks (chronic).

  8. Change in Serum IGF-1

    Time frame: Baseline, immediately after the first session, and 48 hours after the last session (week 8)

    Serum levels of insulin-like growth factor-1 (IGF-1) measured using commercial chemiluminescence immunoassay kits. Samples were collected before and after the first session (acute) and after eight weeks (chronic).

  9. Change in Serum Progesterone

    Time frame: Baseline, immediately after the first session, and 48 hours after the last session (week 8)

    Serum levels of progesterone measured using commercial chemiluminescence immunoassay kits. Samples were collected before and after the first session (acute) and after eight weeks (chronic) to verify menstrual cycle phase.

  10. Change in Serum C-Reactive Protein (CRP)

    Time frame: Baseline, immediately after the first session, and 48 hours after the last session (week 8)

    Serum levels of C-reactive protein (CRP), an inflammatory marker, measured using an enhanced turbidimetric assay. Samples were collected before and after the first session (acute) and after eight weeks (chronic).

Sponsors and collaborators

Lead sponsor

Birjand University of Medical Sciences

Other

Registry information

Official study title

Comparison of Traditional, Standard Cluster, and Undulating Cluster Resistance Training on Hormonal, Inflammatory, and Performance Outcomes in Female Volleyball Players: A Randomized Controlled Trial

Important dates

Study start
2022
Primary completion
2022
Study completion
2022
First posted
Aug 25, 2026
Registry last updated
Aug 25, 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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