Off-season Training Effects on U19 Soccer Players

Comparison of Functional and Traditional Strength and Power Training on U19 Soccer Players During Off-season in Norway: A Randomized Controlled Trial

The goal of this randomized controlled trial is to evaluate whether functional strength and power training or traditional strength and power training during the off-season can improve soccer-specific performance in trained male U19 Norwegian soccer players.

The main questions it aims to answer are:

Does functional training lead to greater improvements in technical soccer skills (passing, shooting, dribbling) compared to traditional training?

Do both training modalities improve mobility, dynamic balance, sprint speed, change of direction, and jumping performance?

Researchers will compare the functional training group, the traditional training group, and a control group to see if either training approach provides superior performance benefits.

Participants will:

Take part in an 8-week intervention.

Complete two weekly strength sessions (functional or traditional depending on allocation).

Attend two weekly soccer sessions during the first 4 weeks (all groups).

Undergo a standardized test battery measuring mobility, balance, technical skills, sprinting, change of direction, and vertical jump before and after the intervention.

Study Overview

• Status: Completed
• Conditions: Soccer Performance
• Intervention / Treatment: Other: Experimental, comparator and control

• Study Type: Interventional
• Enrollment (Actual): 53
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Norway
  • Trøndelag
    • Steinkjer, Trøndelag, Norway, 7714
      • SSA Steinkjer

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 14 years to 16 years (Child, Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria

Male soccer players aged 16-20 years.

Active competitors in the Norwegian G19 0. Division or the Norwegian Tipping League (Senior 3. Division).

Minimum of eight years of organized soccer experience.

At least two years of structured resistance training experience.

No concurrent involvement in other structured physical activity programs.

Exclusion Criteria

History of lower-limb injury within the past three months.

Inability to meet the required training attendance (≥14 out of 16 sessions).

Participation in additional structured training programs outside the intervention.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Factorial Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Intervention; This group will use a functional training system developed specifically for football players to improve their physical strength and movement abilities on the field.	Other: Experimental, comparator and control; To quantify the effect of a strength intervention for footballers on improved range of motion, balance, speed, jump height, and technical football skills compared to a training group performing basic power exercises and machine-based strength training and a control group.
Active Comparator: Positive control; This group will use general strength exercises with the purpose of improving physical strength.	Other: Experimental, comparator and control; To quantify the effect of a strength intervention for footballers on improved range of motion, balance, speed, jump height, and technical football skills compared to a training group performing basic power exercises and machine-based strength training and a control group.
No Intervention: Negative control; Control group A group that is not treated

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Loughborough soccer passing test	Measure precision in passing (Seconds)	Day 1
Loughborough soccer shooting test	Measure precision in shooting and reaction (Points and secounds )	Day 1
Agility with ball	Measure technical abilities with the ball (Seconds)	Day 1
Loughborough soccer passing test	Measure precision in passing (Seconds)	2 months
Loughborough soccer shooting test	Measure precision in shooting and reaction (Points and secounds )	2 months
Agility with ball	Measure technical abilities with the ball (Seconds)	2 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Dynamic leap balance test	Measure improved dynamic balance (Secounds)	Day 1
S180 sprinting test	Measure change of direction abilities (Secounds)	Day 1
Vertical jumping test	Measure jumping abilities (Cm)	Day 1
Dynamic leap balance test	Measure improved dynamic balance (Secounds)	2 months
S180 sprinting test	Measure change of direction abilities (Secounds)	2 months
Vertical jumping test	Measure jumping abilities (Cm)	2 months
10 m and 20 m linear sprint	Measure the ability to accelerate and maximum speed (Seconds; Km/h)	Day 1
10 m and 20 m linear sprint	Measure the ability to accelerate and maximum speed (Seconds; Km/h)	2 months
Active knee extension test	Measure range of motion (Degrees)	Day 1
Active knee extension test	Measure range of motion (Degrees)	2 months
Active dorsi flexion test	Measure range of motion (Degrees)	Day 1
Active dorsi flexion test	Measure range of motion (Degrees)	2 months
Hip External rotation	Measure range of motion (Degrees)	Day 1
Hip External rotation	Measure range of motion (Degrees)	2 months
Hip Internal rotation	Measure range of motion (Degrees)	Day 1
Hip Internal rotation	Measure range of motion (Degrees)	2 months

Collaborators and Investigators

• Sponsor: Aalborg University
• Collaborators: The Research Council of Norway

Study record dates

Study Major Dates

• Study Start (Actual): September 1, 2023
• Primary Completion (Actual): January 14, 2024
• Study Completion (Actual): January 14, 2024

Study Registration Dates

• First Submitted: August 26, 2022
• First Submitted That Met QC Criteria: September 7, 2022
• First Posted (Actual): September 9, 2022

Study Record Updates

• Last Update Posted (Estimated): September 4, 2025
• Last Update Submitted That Met QC Criteria: August 27, 2025
• Last Verified: August 1, 2025

More Information

Terms related to this study

• Keywords: Coordination; Speed; Power; Technical skills
• Additional Relevant MeSH Terms: Wounds and Injuries; Athletic Injuries
• Other Study ID Numbers: 438956

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No