Cluster Training in Female Volleyball Players

Birjand University of Medical Sciences30 enrolled

Overview

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.

Study Type

Interventions

Traditional Resistance TrainingBEHAVIORAL

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 TrainingBEHAVIORAL

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 TrainingBEHAVIORAL

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.

Eligibility

Sex: FEMALEMin age: 18 YearsMax age: 30 YearsHealthy volunteers:

Medical Language ↔ Plain English

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

Outcomes

Primary Outcomes

Change in Relative Peak Power

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.

Time frame: baseline and after 8- week

Secondary Outcomes

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

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.

Time frame: Baseline and 8 weeks

Change in Speed (20-m Sprint)

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

Time frame: baseline and after 8- week

Change in Agility

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.

Time frame: baseline and after 8- week

Change in Countermovement Jump (CMJ) Height

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.

Time frame: baseline and after 8- week

Change in Relative Peak Power

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.

Time frame: baseline and after 8- week

Change in Serum Testosterone

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).