It's the classic coaching dilemma: how do you fit everything into a packed training week? Between skill work, conditioning, and recovery, strength training often gets squeezed. Many programs default to a single, full-body lift per week, hoping it's enough to move the needle. But is it?
A recent study published in the International Journal of Sports Physiology and Performance tackles this question head-on, comparing the effects of one versus two resistance training sessions per week in young, trained soccer players. The results provide a clear answer for coaches and athletes looking to optimize performance and durability.
Disclaimer: This article is a review of the study's abstract, as the full text was not available.
The Study: Setting the Stage
Researchers took forty young male soccer players (average age ~16.6) and split them into two groups for an entire season:
- Frequency 1 Group (F1G): Performed one resistance training (RT) session per week.
- Frequency 2 Group (F2G): Performed two RT sessions per week.
Crucially, both groups followed an "integral periodization" model, meaning their weight room work was designed to complement and support their on-field training loads, not just add random stress.
Over the season, the scientists tracked changes in key performance metrics: vertical jump (CMJ), squat and hip thrust strength, 10-meter and 30-meter sprint speed, agility (V-Cut test), and endurance (30-15 Intermittent Fitness Test). They also meticulously recorded all noncontact injuries.
The Results: Twice a Week is the Clear Winner
While one session per week was better than nothing, the group lifting twice a week saw far superior results across the board.
Strength Gains
Both groups got stronger. The one-session-per-week group saw significant improvements in their squat and hip thrust. However, the two-sessions-per-week group's improvements were significantly greater. If maximal strength is the goal, doubling the frequency delivered a much bigger payoff.
Speed and Acceleration
This is where the difference becomes undeniable. The group lifting twice a week got significantly faster, posting better times in both the 10-meter and 30-meter sprints.
In contrast, the group lifting only once a week saw no significant improvements in their sprint times. This is a critical finding: if you want to build a faster athlete, one lift a week might not be enough to get the job done.
Injury Reduction
Perhaps the most compelling finding for long-term athletic development was the impact on injuries. The group training twice a week experienced a significant reduction in the severity of noncontact injuries.
Lifting more frequently didn't just make the players more powerful and faster; it made them more robust and resilient to the demands of their sport.
Where Was the Difference Minimal?
To be fair, it wasn't a total blowout. Both groups saw similar improvements in their countermovement jump and V-Cut agility test results, with no significant difference between them. Neither group saw significant changes in the 30-15 Intermittent Fitness Test, suggesting that this particular RT program wasn't geared toward improving that specific endurance quality.
Practical Takeaways for Your Training
This study provides clear, actionable insights for structuring an athlete's training week:
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One Session is Good, Two is Better: If you're completely time-crunched, one session per week can still yield improvements in strength and agility. It's a viable minimum effective dose.
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Prioritize Two Sessions for Speed and Resilience: If you want to build faster, more explosive athletes who are less likely to suffer severe injuries, the evidence points strongly toward making time for a second lifting session. The superiority in sprint performance and injury severity reduction is too significant to ignore.
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Integrate, Don't Isolate: The success of this program was based on an "integral periodization" model. Your strength training should work in harmony with your sport-specific training, not as a separate, conflicting stressor.
For athletes and coaches, the message is clear. While one trip to the weight room is a start, making space for that second session could be the key to unlocking new levels of speed, strength, and season-long durability.
Reference:
Jimenez-Iglesias J, Castro-Piñero J, Landi-Fernández M, Perez-Bey A, de la Pascua-Roca E, Gonzalo-Skok O. (2025). Comparative Effects of 2 Different Frequencies of Resistance Training in an Integral Periodization Approach on High-Intensity Actions and Noncontact Injuries in Young Trained Soccer Players. International journal of sports physiology and performance.