Heavy Strength Training Improves Cycling Performance—But the Effect Size Might Surprise You

Should endurance cyclists lift heavy? The short answer from a new 2026 meta-analysis published in the European Journal of Applied Physiology is "yes, probably"—but with more caveats than you'd expect. Researchers Cristian Llanos-Lagos, Rodrigo Ramirez-Campillo, and Eduardo Sáez de Villarreal analyzed heavy strength training effects on physiological determinants of endurance cycling performance, finding improvements in time to exhaustion and time trial performance, but with low certainty of evidence and significant variability across studies.

The meta-analysis, published July 2025 and indexed through February 2025, examined randomized and non-randomized controlled studies where endurance cyclists (aged 18+) performed heavy strength training for at least 3 weeks. The outcome measures included VO2max, peak power at VO2max, maximal metabolic steady state, cycling efficiency, anaerobic capacity, anaerobic power, and crucially, cycling performance metrics like time to exhaustion and time trials.

What "Heavy" Actually Means

Heavy strength training in this context means loads ≥80% of one-repetition maximum (1RM), typically performed for 3-6 repetitions per set with full recovery between sets. This differs from muscular endurance work (lighter loads, higher reps, shorter rest) or hypertrophy-focused training (moderate loads, 8-12 reps). The rationale: heavy loads recruit high-threshold motor units and improve neuromuscular coordination without adding significant muscle mass—a critical distinction for cyclists concerned about power-to-weight ratios.

The exercises varied across studies but typically included squats, leg presses, leg curls, and sometimes upper-body movements. Training frequency ranged from 2-3 sessions per week, with intervention durations spanning 3-16 weeks. The meta-analysis found no significant effect of intervention duration, training frequency, or total sessions on outcomes—suggesting that strength training benefits plateau relatively quickly or that individual response variability swamps the aggregate signal.

The Performance Gains

Here's where it gets interesting: heavy strength training improved time to exhaustion and time trial performance, but the effect sizes were modest and the certainty of evidence was rated low. That means while the direction of the effect is positive, the magnitude varies considerably between individuals and study designs, and we can't be highly confident in precise predictions for any given cyclist.

Why low certainty? Several factors: heterogeneity in training protocols (some studies used back squats, others leg presses), variability in participant training status (recreational cyclists versus competitive racers), differences in concurrent endurance training volumes, and small sample sizes in many included studies. The researchers applied GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology, which downgraded certainty due to these limitations.

The Physiological Mechanisms

Despite modest performance gains, the physiological adaptations are well-documented. Heavy strength training improves:

Neuromuscular efficiency: Better recruitment and synchronization of motor units means producing the same power output with less muscular effort. This becomes critical during long rides when fatigue accumulates—your muscles can maintain force production more efficiently.

Rate of force development: Cycling isn't just about sustained power; it's about rapid force application during accelerations, climbs, and sprints. Heavy strength training improves how quickly you can generate force at the start of each pedal stroke.

Tendon stiffness: Stiffer tendons transmit force more effectively from muscle to pedal. This isn't about injury risk (appropriately stiff tendons are protective)—it's about power transfer efficiency.

Cycling economy: Some studies within the meta-analysis found improved cycling economy—the oxygen cost at a given submaximal workload decreased after strength training. That means you're burning less oxygen to maintain the same pace, theoretically extending endurance.

The Diminishing Returns Problem

Here's the practical challenge: if you're already training 15+ hours per week on the bike, adding 2-3 hours of strength training means either reducing cycling volume or increasing total training load. The meta-analysis couldn't definitively answer whether the performance gains from strength training outweigh the potential benefits of spending those same hours doing more cycling-specific work.

For time-crunched cyclists training 8-10 hours weekly, the calculus shifts. Two 45-minute strength sessions might deliver better marginal gains than two additional 45-minute endurance rides, especially if your cycling volume is already optimized. The key is integration—strength training shouldn't compromise recovery or interfere with high-intensity cycling sessions.

Polarized Meets Heavy: The Periodization Question

Interestingly, this strength training research intersects with polarized training methodology. If you're following an 80/20 intensity distribution on the bike, when do you schedule heavy strength sessions? The answer: not on hard days. Strength training creates neuromuscular fatigue that can blunt the quality of high-intensity intervals. Instead, schedule strength work on easy cycling days or rest days, treating it as a separate training stimulus that complements rather than competes with cycling intensity.

The U23 case study presented at Science & Cycling 2026 (Kamiel Eeman's season plan) illustrates this periodization. Winter training included heavy strength work during low-volume, polarized cycling. As race season approached and cycling volume increased, strength training shifted to maintenance mode—1-2 sessions weekly with lower volume to preserve adaptations without adding fatigue.

What This Means for Your Riding

If you're not currently doing heavy strength training, the meta-analysis suggests you should consider adding it—but temper expectations. You're unlikely to see dramatic FTP gains or suddenly drop minutes off your time trial. What you might gain: better neuromuscular efficiency during long rides, improved power output during short, hard efforts, and potentially reduced injury risk from improved lower-body strength and tendon resilience.

Start with 2 sessions weekly, focusing on compound lower-body movements: squats (back or front), deadlifts, and single-leg work like split squats. Progress from 3 sets of 5 reps at 80% 1RM to 4-5 sets as adaptation occurs. Include adequate rest between sets (2-3 minutes) to maintain intensity. Don't sacrifice cycling quality for gym volume—if strength sessions are compromising your ability to hit interval targets, reduce frequency or volume.

The low certainty of evidence means individual response will vary. Some cyclists see noticeable performance improvements; others see minimal change. The only way to know is systematic trial: add strength training for 8-12 weeks while monitoring cycling performance metrics (FTP, time trial results, subjective effort at threshold). If performance stagnates or declines, the added training stress may outweigh benefits. If performance improves, you've identified a productive training stimulus.

Heavy strength training isn't a magic bullet for endurance cycling, but the 2026 meta-analysis confirms it's a legitimate performance tool with physiological mechanisms that make sense. The question isn't whether it works in theory—it's whether it works for you, within your total training context, without compromising the cycling-specific volume and intensity that remain the primary drivers of performance.