What muscles does cycling work? A physiologist’s guide to building power

From the explosive push of the quadriceps to the stabilizing tension of the core, cycling recruits more than just your legs. Here is a breakdown of the biomechanics, how to optimize your pedal stroke, and why your bike fit matters for long-term joint health.

The relationship

Cycling is often categorized strictly as a lower-body cardiovascular activity, but for the male physiology, it serves as a unique metabolic and muscular stimulus. Unlike running, which involves high-impact ground reaction forces, cycling is a closed-kinetic-chain exercise. This means your foot is fixed to the pedal, allowing for consistent force application throughout a rotational movement. This distinction allows men to generate high muscular torque with minimal eccentric loading (muscle damage from lengthening), making it a sustainable tool for lifelong fitness and leg hypertrophy.^[1]

When asking what muscles does cycling work, the answer depends heavily on the rider’s position and the terrain. While the legs are the primary engines, the trunk and upper body act as the chassis. If the chassis is weak, the power generated by the engine cannot be effectively transferred to the wheels. Research indicates that high-intensity cycling significantly improves insulin sensitivity and lipid profiles in men, largely due to the massive glucose uptake required by the quadriceps and glutes—the largest muscle groups in the body.

However, the relationship between man and machine is not automatic. The “biking muscles” only fire correctly if the bike fit is dialed in. A saddle that is too low forces the quads to do all the work, neglecting the glutes and straining the patellar tendon. A saddle that is too high destabilizes the pelvis, forcing the lower back muscles to compensate. Understanding this muscular interplay is the first step toward riding faster with less pain.

How it works

To understand exactly what muscles does cycling work, we have to look at the pedal stroke as a clock face. Muscle activation does not happen all at once; it occurs in a precise firing sequence. Electromyography (EMG) studies, which measure electrical activity in muscles, divide the pedal stroke into two main phases: the power phase and the recovery phase.^[2]

The Power Phase (12:00 to 5:00)

The majority of power is generated when the pedal moves from the top dead center (12 o’clock) down to about 5 o’clock. As your hip extends, the gluteus maximus initiates the movement. This is the largest muscle in the body and provides the initial torque.

Simultaneously, the quadriceps (specifically the vastus lateralis and vastus medialis) engage to extend the knee. This combination of hip extension and knee extension creates the massive downward force that propels the bike forward. If you are climbing out of the saddle, the glute activation increases significantly to stabilize the pelvis against gravity.

The Transition and Sweep (5:00 to 8:00)

As the pedal reaches the bottom of the stroke, the gastrocnemius and soleus (calf muscles) activate to plantarflex the foot (point the toes downward slightly). This action is often described as scraping mud off the bottom of your shoe. It transfers the force generated by the upper leg into the pedal before the upstroke begins.

This is also where the hamstrings (biceps femoris) begin to take over. While the quads push, the hamstrings act partly to stabilize the knee and partly to begin pulling the pedal back. This transition is critical for efficiency; a jerky transition at the bottom of the stroke is a common cause of wasted energy.

The Recovery Phase (8:00 to 12:00)

During the upstroke, the goal is not necessarily to generate power, but to get the leg out of the way so the opposite leg can push down effectively. The hamstrings continue to flex the knee, pulling the heel toward the buttock.

As the pedal approaches the top, the hip flexors (iliopsoas) and the rectus femoris (a muscle that acts as both a quad and a hip flexor) lift the thigh. Strong hip flexors are essential for high-cadence cycling (pedaling fast), as they help snap the leg over the top of the pedal stroke to begin the power phase again.

The Stabilization System: Core and Upper Body

While the legs move dynamically, the upper body performs an isometric contraction—muscles tense without changing length—to provide a stable platform. The rectus abdominis and obliques brace the torso, preventing the hips from rocking side to side. The erector spinae (lower back muscles) maintain a neutral spine angle.

The triceps, anterior deltoids (shoulders), and latissimus dorsi (back) support your weight on the handlebars. In road cycling, where the posture is more aggressive and aerodynamic, the load on the triceps and shoulders increases. During a sprint or a steep climb, the upper body engages violently to pull against the handlebars, providing leverage for the legs to push harder.

Conditions linked to it

While cycling is low-impact, the repetitive nature of the movement—often 5,000 revolutions in a single hour—can lead to specific overuse injuries and male-specific health concerns.

Patellofemoral Pain Syndrome (Cyclist’s Knee): This is the most common overuse injury in cycling, characterized by pain around the kneecap. It is frequently caused by quad dominance, where the outer quad muscle pulls the kneecap off-track, or by a saddle that is set too low or too far forward.^[3]

Pudendal Neuralgia and Urological Issues: For men, the saddle acts as a wedge that can compress the perineum (the area between the scrotum and anus). This compression can restrict blood flow and impinge the pudendal nerve, leading to penile numbness and, in chronic cases, temporary erectile dysfunction. Modern cut-out saddles and proper bike fitting have largely mitigated this risk, but it remains a critical consideration for male cyclists.^[4]

Low Bone Mineral Density: Because cycling is a non-weight-bearing sport, exclusive cyclists may develop lower bone density compared to runners or weightlifters. This condition, sometimes called osteopenia, increases the risk of fractures if a crash occurs. Men who cycle exclusively should incorporate resistance training to maintain skeletal strength.^[5]

Symptoms and signals

Your body provides clear feedback when your muscles are being recruited incorrectly or your bike fit is poor. Watch for these signals:

• Burning in the front of the knee: Usually signals a saddle that is too low, placing excessive strain on the quadriceps and patellar tendon.
• Pain behind the knee: Often indicates a saddle that is too high, causing the hamstrings to overstretch at the bottom of the stroke.
• Numbness in the hands: Suggests weak core muscles. When the core fatigues, riders collapse their weight onto the handlebars, compressing the ulnar nerve.
• Lower back tightness: A sign that the glutes are not firing properly. The lower back (lumbar erectors) creates a fake stability to compensate for lazy glutes.
• Rocking hips: Visible from behind, this indicates the saddle is too high, forcing the rider to reach for the pedals at the bottom of the stroke.

What to do about it

To maximize the benefits of the biking muscles and minimize injury risk, follow this three-step protocol.

1. Get a Professional Bike Fit: Before worrying about training zones, ensure your machine fits your body. A clinical bike fit adjusts the saddle height, fore/aft position, and handlebar reach to ensure your knee tracks over your foot and your pelvis remains stable. This is the single most effective intervention for preventing injury.
2. Train the “Antagonist” Muscles: Cycling is repetitive and occurs in a hunched, flexed position. To balance this, men should perform resistance training that focuses on extension. Key exercises include deadlifts, kettlebell swings, and face pulls. These movements strengthen the posterior chain and open up the chest, countering the cyclist’s hunch.
3. Monitor Training Volume: Increase your mileage gradually. The cardiovascular system (heart and lungs) often adapts faster than the musculoskeletal system (tendons and ligaments). A sudden spike in distance or intensity is a primary recipe for tendonitis.

Myth vs Fact: Building Cycling Power

Bottom line

Cycling is a powerhouse exercise that targets the quadriceps, glutes, hamstrings, and calves while demanding significant stability from the core. For men, it offers a high-yield cardiovascular workout that spares the joints from impact, provided the bike fit is correct. By understanding the biomechanics of the pedal stroke and supplementing time in the saddle with resistance training, you can build a resilient, powerful physique that performs as well off the bike as it does on the road.

References

1. Ozaki H, Loenneke JP, Thiebaud RS, et al. Cycle training induces muscle hypertrophy and strength gain: strategies and mechanisms. Acta physiologica Hungarica. 2015;102:1-22. PMID: 25804386
2. Hug F, Dorel S. Electromyographic analysis of pedaling: a review. Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology. 2009;19:182-98. PMID: 18093842
3. Clarsen B, Krosshaug T, Bahr R. Overuse injuries in professional road cyclists. The American journal of sports medicine. 2010;38:2494-501. PMID: 20847225
4. Awad MA, Gaither TW, Murphy GP, et al. Cycling, and Male Sexual and Urinary Function: Results from a Large, Multinational, Cross-Sectional Study. The Journal of urology. 2018;199:798-804. PMID: 29031767
5. Olmedillas H, González-Agüero A, Moreno LA, et al. Cycling and bone health: a systematic review. BMC medicine. 2012;10:168. PMID: 23256921