The Case for Lifting Heavy In-Season: Injury Resilience and the Force-Velocity Connection in Soccer

During the competitive season, many athletes and parents instinctively reduce or avoid strength training, fearing fatigue or injury. However, when programmed correctly, maintaining high-intensity lifting serves a critical role in protecting athletes against soft tissue injuries and preserving the neuromuscular qualities needed for elite performance.

This is where RSI (Reactive Strength Index Testing) and sub-maximal lifting come together to ensure players readiness and well-being.

RSI is a measure of how quickly an athlete can transition from eccentric (landing) to concentric (takeoff) phases during a plyometric movement—typically assessed via drop jumps or depth jumps.

During the competitive season, athletes are exposed to high CNS and muscular fatigue from training, matches, and travel. RSI serves as a non-invasive, repeatable way to track:

• Neurological freshness

• Tendon and muscle function

• Force transmission capacity

• 
  

If RSI is significantly reduced (>10–15% from baseline), this may signal the need to:

• Lower the load or intensity of strength sessions that week

• Prioritize recovery modalities

• Avoid plyometrics or high-velocity sprint work

If they are recovered and show readiness, then we can proceed into adjusting the load of the strength work.

Moving on with thoughts of how the players move within the game.

Soccer is a sport with high volumes of eccentric braking, rapid accelerations, and explosive decelerations. A player performs hundreds of explosive actions—sprints, changes of direction, and jumps—each requiring rapid force generation. Peak sprint efforts in professional players have been shown to exceed 5.0x bodyweight in ground reaction forces (Morin et al., 2015).

Heavy resistance training (loads ≥ 80–85% 1RM) targets the high-force, low-velocity end of the curve. Maintaining this end is critical for enhancing or preserving force production, even when game speed occurs at high velocity.

Why does this matter?

During match play, athletes rely on high-velocity force expression—sprinting, changing direction, and decelerating—all of which demand strong neural output and rapid recruitment of high-threshold motor units.

If you remove heavy strength training during the season:

• Neural drive diminishes

• Maximal force outputs drop

• The athlete slides leftward on the force-velocity curve (less force at any speed)

• Injury risk increases as tissues lose their ability to absorb and redirect force (e.g., during deceleration)

“Heavy loading is essential to maintain the neuromuscular qualities underpinning high-speed locomotion, particularly in hamstrings and posterior chain musculature.” — Suchomel et al., 2016

In-season strength isn’t just about maintenance—it’s about preserving access to force. Without high-intensity resistance training, athletes lose the capacity to express velocity-specific power, and that translates to slower sprints, weaker cuts, and a higher risk of injury when reacting at full speed.

Multiple studies demonstrate a link between strength levels and injury prevention. Tim Gabbett’s load management research shows that chronic exposure to moderate-to-high loads builds tissue capacity, while sudden drops in training load can increase injury risk.

• Hamstring Example: High eccentric strength (measured via Nordic Hamstring testing) correlates with reduced hamstring injuries, especially in soccer and rugby populations.

So what's the framework look like for performance coaches that work with soccer players?

Guidelines or Protocol:

• Frequency: 1–2x/week

• Intensity: 80–90% 1RM

• Volume: Low (2–3 sets of 2–4 reps)

• Focus: Posterior chain (RDLs, Trap Bar DLs), unilateral work (Bulgarian SS), and eccentric strength (Nordics, Copenhagen planks)

Sample Rotation (Post 48h match recovery):

• Monday or Tuesday (MD+1/2): Lower Body (Heavy Trap Bar Deadlifts, Nordics)

• Thursday (MD-2): Priming Neural Session (Loaded jumps, low volume sprints)

Again low volume is key, most players won't "feel" like doing this, depending on the previous MD loads, however 2 sets is a a sweet spot.

Parents and athletes often treat in-season training as a maintenance afterthought. Yet, in elite programs (Premier League, MLS, La Liga), in-season lifting is non-negotiable for performance and durability. Reframing the narrative to reflect this standard ensures our athletes are prepared, not just preserved.

The game doesn't lower its demands in-season—so neither should our strength protocols. By continuing to lift heavy, athletes protect themselves, stay neurologically sharp, and better express power on the pitch.

If you're a player, parent, or coach looking to integrate smart, season-friendly strength training into your routine, check out our Perform First App. We offer tailored in-season programs that keep your performance high and your injury risk low—all built on real sports science.