Who has stronger legs – runners or cyclists?

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Both endurance activities are great for cardiovascular health, but which is better when it comes to building lower limb strength? Mdf Table

Who has stronger legs – runners or cyclists?

Ever found yourself in a petty debate with your mates about which sport is better: running vs cycling? Perhaps you've squabbled over which sport makes you fitter, or even, who has stronger legs – runners or cyclists?

Well, next time you find yourself in a quarrel over that latter point, you might want to reference this very article.

To find out how each sport works our leg muscles differently, leading to differing strengths and physiques between runners and cyclists, we asked Dr Robin Chatterjee, consultant in musculoskeletal, sport and exercise medicine at Chelsea Outpatient Centre, part of HCA Healthcare UK, for some answers.

We also caught up with Jack Hutchins, pro triathlete and coach at Scientific Triathlon, to find out how incorporating cycling into your training week may help to improve running performance and reduce the risk of injury.

Broadly speaking, running and cycling are lower-limb forms of exercise and use the four main leg muscle groups: quadriceps, calves, glutes and hamstrings. But the action of each works them in different ways.

When pedalling, cyclists use the quads and the glutes to produce power – the quads just before the top of the stroke through to the bottom, while the glutes contribute to generating power while also stabilising the hip. The hamstrings take care of six o’clock to nine o’clock of the pedal stroke and keep the knee stable when the leg is fully extended, while the calves help with ankle stability.

'The most important muscles [for cyclists] are the quadriceps – the muscles at the front of your thighs,' says Chatterjee. 'Cyclists often have these massive upper thighs – the reason is the constant pedalling action that leads to the over-development of the quads compared to the hamstrings or the glutes.'

It’s why cyclists’ legs may sometimes appear bigger than runners'. 'It's not that the other [muscles] aren't getting bigger and stronger or that you're not using them when cycling, it’s just the amount you're using the quads exceeds all the others, so [cyclists] may have big thighs and slimmer calves,' he adds.

The running equivalent of the pedal stroke is the gait cycle which describes how we run. This is split into the stance phase, where part of the foot is touching the ground and the foot and leg bear your bodyweight, and the swing phase, where that same foot is suspended in the air.

During these phases, the leg’s muscle groups perform a balanced role in propelling you forward, while preventing your joints from buckling beneath you with every load-bearing step. The quads extend and stabilise the knee and drive the hip to start the swing phase, and the glutes stabilise the hip, pelvis and femur while also extending the leg at the hip to aid forward propulsion. The hamstrings, meanwhile, work alongside the glutes during leg extension, allowing you to bend your knee when driving forward, and the calves soak up the impact every time you land before acting as a spring to drive your leg up on toe-off.

Runners, therefore, tend to have a better strength balance between the quads, hamstrings, glutes and calves, when compared to cyclists, but asymmetries between these muscles are still common in runners.

For example, one study found that recreational runners have stronger quadriceps than hamstrings and concluded that a more balanced strength ratio between the two may help to improve running economy.

Moreover, strength imbalances are commonly the cause of injuries, so for example quad dominant runners are more susceptible to patellofemoral pain syndrome (more commonly known as runner’s knee) due to increased stress on the knees.

Aside from the key leg muscle groups, both forms of exercise require many more intricate muscles and tendons to keep you moving forward. The main supporting cast that running uses are:

Cycling, meanwhile, recruits muscles including:

Given the ways in which the action of cycling and running recruit muscles in different ways and to varying degrees, it's hard to compare leg strength like-for-like between runners and cyclists.

If defining strength as the greatest load that can be lifted, pushed or pulled, then there will be some differences in leg strength between a similarly aerobically trained runner and cyclist, so this is best compared in specific muscles or muscle groups, rather than looking at the legs as a whole.

'They will be stronger in a different way,' says Chatterjee. 'The calves of a runner are likely to be stronger than the calves of a cyclist, whereas the quads of cyclists are likely to be stronger than the quads of a runner. So depending on what weights you're lifting, you could argue that one is stronger than the other.'

It's worth mentioning that the two forms of exercise also develop different fibres within our muscles at different ratios.

'We all have fast-twitch and slow-twitch [muscle] fibres and the ratio alters based on your activity,' explains Chatterjee. Every skeletal muscle (those used to move your bones) contains both fast and slow-twitch muscle fibres; the former is used for rapid, explosive movements like sprinting or jumping, while the latter is endurance-focused.

'Cyclists have [more] fast-twitch fibres – that type of muscle that generates power, which you need for sprints, climbs or long distance cycling. Whereas runners have [more] slow-twitch fibres, which are more fatigue resistant and better for endurance running.'

Pro triathlete and coach Jack Hutchins says that integrating cycling into a runner's training can have myriad benefits.

'Look at who's winning all the biggest cross-country races in the UK – Hugo Milner, Callum Johnson, Alex Yee – they're all triathletes, while triathlete Hayden Wilde just ran a 13:23 5K. And their run mileage is [relatively] low.'

The performance benefit, says Hutchins, is the result of an increased training load – in terms of both volume (duration) and intensity (how hard). If you’re just relying on running to do this, it can be difficult, particularly if your legs aren’t conditioned to ramp up the training load or you’re injury-prone. While beneficial for improving fitness and muscular endurance, long runs incur stress on the body and need to be incorporated into a runners' training gradually and sensibly – including with plenty of recovery time– to reduce risk of injury.

'Cycling’s relatively similar to running and you're still using a lot of the same muscles, but is a much safer way to get more total volume in,' explains Hutchins. 'You can ride easily over three, four, five hours on the bike, whereas you're not going to go out for a five-hour run – some people can, but for that to be a regular addition to a training schedule is pretty much impossible.'

'These long-duration workouts on the bike create significant metabolic stress and elicit some really good physiological benefits because you accumulate fatigue metabolites. The fitness transfers are not just cardiovascular – cycling uses similar muscle groups but recruits muscle fibres in a different way. You could do it [create the same training effect] by doing loads of double run days, but by having those one or two three to four hour sessions a week in your schedule, you get that different and additional stimulus you can't really get running.'

Hutchinson points out that long rides can even be fun! 'On a bike, you can get out and explore all day, which is good fun and stop for lunch. If athletes can incorporate a training session into a nice day out, they will probably do more training.'

If you don't own a bike, though, or you are a nervous cyclist, you can elicit the same training benefit by using an indoor bike or turbo trainer.

The way in which you fit sessions into your run training will depend on what your running goals are for the year but Hutchins suggests using cycling as part of building your base fitness before embarking on a training plan.

'Rather than doing loads of run volume all-year round, you can be a little bit more precise and use more cross training in the winter, base season or build phase and then save that increase in run volume for the competition or specific [phase] as you're leading into your big 'A' race.'

Chatterjee does, however, caution that while combing the two may reduce the risk of injury for some, be mindful that it's not a magic bullet as, in doing so, 'you are taking on the risk of injury from both [sports]', citing buttock pain and lower back pain as niggles sometimes seen in cyclists.

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