Why More Leg Muscle Might Not Always Mean Better Cycling Efficiency
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When it comes to cycling, most people assume that bigger and stronger leg muscles will always lead to better performance. While this might be true for sprinting or short bursts of power, new research suggests that having more leg muscle mass could actually reduce efficiency during moderate-intensity cycling. Let’s break down what that means and why it matters.
What Is Cycling Efficiency?
Cycling efficiency is about how well your body converts the energy it uses into actual movement on the bike. In this study, scientists looked at something called gross mechanical efficiency (GE). GE compares the mechanical power you produce while cycling to the total energy your body spends to create that power. The higher your GE, the less energy you waste for a given output. They also looked at delta efficiency (DE), which focuses on the energy changes as workload increases.
The Study in a Nutshell
Twelve healthy young men who were not trained cyclists took part in the study. Their leg muscle mass was measured using MRI scans, and they performed an incremental cycling test where the resistance increased every three minutes until they could not continue. The researchers recorded oxygen uptake, power output, and efficiency during moderate-intensity cycling—specifically, below each participant’s lactate threshold.
Key Findings
The surprising result was that greater leg muscle mass was linked to lower gross mechanical efficiency during moderate-intensity cycling. In simpler terms, those with bigger leg muscles used more energy to produce the same amount of power. However, leg muscle mass did not affect delta efficiency.
So why does this happen? The study points to two main reasons:
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Higher Resting Oxygen Use
Muscles consume oxygen even at rest. More leg muscle means a higher baseline oxygen demand, which adds to the total energy cost during cycling. This extra cost pushes efficiency down.
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Increased “Internal Work”
Internal work refers to the effort required to move your own legs during the pedaling motion. Bigger muscles are heavier, and moving them takes more energy—even before you add the resistance of the bike.
Interestingly, the researchers found that the extra oxygen needed for simply moving heavier legs explained a much larger part of the reduced efficiency than the higher resting oxygen cost.
What This Means for Cyclists
For casual or endurance-focused cyclists, the findings are important. If your goal is to ride longer at a steady pace, chasing bigger leg size in the gym might not help and could even slightly hurt your efficiency. Instead, training should focus on improving muscle endurance, pedaling technique, and cardiovascular capacity.
That doesn’t mean strength training is bad for cyclists. Stronger muscles can improve sprint power, climbing ability, and injury prevention. But if efficiency over long distances is the goal, it’s worth balancing muscle growth with endurance training.
Practical Tips to Improve Cycling Efficiency
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Prioritize Endurance Training
Long rides, tempo sessions, and interval training help your muscles use oxygen more effectively.
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Work on Pedal Technique
Smooth, circular pedaling can reduce wasted effort and make better use of available power.
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Maintain a Balanced Strength Program
Include lower-body strength exercises, but avoid excessive hypertrophy if endurance is your main target.
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Focus on Aerobic Conditioning
A strong cardiovascular system supports more efficient energy use during moderate efforts.
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Optimize Bike Fit
A well-fitted bike can reduce unnecessary muscle strain and improve comfort, which supports better efficiency.
The Bottom Line
More leg muscle can be great for power and sprinting, but when it comes to steady, moderate cycling, bigger isn’t always better. Efficiency is about how well you convert energy into movement, and this study shows that too much muscle mass in the legs can work against you in that specific context. If your goal is long-distance or endurance cycling, train for strength, but keep efficiency in mind.