Here's a claim that will make a lot of cyclists uncomfortable: the gym might be exactly where they should be spending more time. Not instead of riding, but alongside it. The evidence has been stacking up for years, and the 2025 meta-analysis in European Journal of Applied Physiology is probably the clearest picture we have yet — heavy strength training meaningfully improves cycling performance, and it does so through mechanisms that your aerobic training simply cannot replicate.
What "works" actually means here
When cyclists say they want to improve, they usually mean they want to go faster for longer. That improvement comes from a handful of physiological levers: your VO2max (the ceiling on how much oxygen your body can use), your metabolic steady state (the highest intensity you can sustain aerobically), your cycling efficiency (how much power you produce per litre of oxygen consumed), and your anaerobic power (what you can put out when you go over that aerobic ceiling). Strength training, perhaps counterintuitively, doesn't move the first two levers much. Across the 17 studies in that meta-analysis, combining roughly 262 participants with mean VO2max values around 61 ml/kg/min, heavy lifting showed no significant effect on VO2max or maximal metabolic steady state.
That sounds like bad news until you look at what it does change. Cycling efficiency improved with a moderate effect size (ES = 0.353), anaerobic power improved substantially (ES = 0.560), and overall cycling performance — measured across time trials and time-to-exhaustion tests — improved with an effect size of 0.463. In plain language: strength training makes you more economical on the bike and harder to crack when the racing turns explosive. Neither of those adaptations comes from more Zone 2 or sweet spot work.
The mechanisms behind the adaptation
The "why" here is worth understanding, because it changes how you think about programming. When you do heavy resistance training — think squats, leg press, Romanian deadlifts at 80% or more of your one-rep max — your neuromuscular system adapts in ways that carry over directly to pedalling. Specifically, you train your body to recruit fast-twitch muscle fibres more efficiently and, over time, to convert some of the most fatigable type IIX fibres into the more fatigue-resistant type IIA variety. Your tendons and connective tissue also stiffen, which means more of the force you generate gets transmitted into the pedal rather than absorbed as elastic deformation.
The net effect is that at submaximal intensities — which is where you spend most of a race or long sportive — you're using a smaller proportion of your total motor unit pool to produce the same power. Your legs have more in reserve. Slow-twitch fibres carry more of the load, fast-twitch fibres stay fresh, and your energy cost per watt drops. That's cycling efficiency improving in real time.
A 2024 randomised controlled study in Cureus made this concrete by comparing conventional strength training, core exercises, and no strength training in 36 trained road cyclists over 12 weeks. Power outputs were tested across 5-second, 60-second, 5-minute, and 20-minute durations. Conventional strength training outperformed core training across all four time windows. Not slightly — meaningfully. Core work, for all its value in injury prevention, is a poor substitute for the neuromuscular adaptations you only get from moving heavy loads through full range of motion.
How to actually structure it alongside your riding
The most common mistake is treating the gym as an afterthought — a 20-minute bolt-on after a long ride when your legs are already cooked. That approach almost guarantees suboptimal adaptation and a higher injury risk. Strength training needs its own dedicated sessions, ideally on lighter riding days or the day after a hard interval session (not before). Two sessions per week is the sweet spot for most amateurs: enough stimulus to drive adaptation, not so much that it competes with your cycling volume in a way that wrecks your recovery.
In the off-season and early base phase, this is the window to go heavier — 3 to 5 sets of 4 to 6 reps at truly challenging loads. Squats, leg press, step-ups, single-leg Romanian deadlifts, and hip hinge variations. Upper body work matters too, especially rowing movements that counteract the forward-flexed position of cycling, and core stability work for the platform from which your legs push. As the race season approaches, most coaches recommend transitioning to lower volume, higher velocity work (2–3 sets, more explosive) to maintain the neuromuscular adaptations without accumulating fatigue.
One thing worth saying to time-crunched riders specifically: yes, this adds hours to your training week. But the evidence suggests it can reduce the total cycling hours needed to achieve a given performance level, because you're becoming more efficient per pedalstroke. If you're already using an AI cycling coach to plan your training load, the key is making sure your gym sessions show up in the fatigue model — otherwise you'll be under-recovering and wondering why your intervals feel terrible.
A note for masters riders
If you're over 40, the case for strength training becomes even more straightforward. Aerobic capacity declines with age at roughly 1% per year after your early thirties, and there's not a lot you can do about that trajectory. Muscle mass, however, declines faster — and strength training is one of the few interventions that reliably slows it. A 2024 study of 555 male master cyclists found that strength training practices were common but inconsistently applied, often dropped in favour of more riding when time got tight. That's exactly backwards. Holding onto the muscle you have, and the bone density that comes with heavy loading, is protective both for performance and for long-term health. The rider who can still produce 4 watts per kilogram at 55 is almost certainly the one who never stopped picking up heavy things.
There's also a practical edge case worth mentioning: if you're newer to cycling, the strength gains from gym work will be proportionally larger than they are for well-trained riders, simply because you're starting from a lower base. The research generally shows that trained cyclists (VO2max around 60 ml/kg/min) still benefit significantly, but less-trained riders tend to see faster initial returns. Don't wait until you're "fit enough" to start — the gym is partly how you get there.
Sources
Spiering et al. (2025). Heavy strength training effects on physiological determinants of endurance cyclist performance: a systematic review with meta-analysis. European Journal of Applied Physiology. link.springer.com
Rønnestad & Mujika (2014). Optimizing strength training for running and cycling endurance performance. Scandinavian Journal of Medicine & Science in Sports, 24(4), 603–612.
Martínez-Aranda et al. (2024). Influence of conventional resistance training compared to core exercises on road cycling power output. Cureus. pmc.ncbi.nlm.nih.gov