When it comes to building biceps, two dominant tools dominate the gym floor: cable machines and free weights. Both are effective, widely used, and supported by experienced athletes and trainers.
But which of the two provides the most effective stimulus for biceps hypertrophy and strength development? In this article, we dissect the biomechanical, physiological, and practical differences between cable and free weight exercises to determine which builds better biceps, using evidence from peer-reviewed studies and expert consensus.
Understanding Biceps Anatomy and Function
The biceps brachii is a two-headed muscle composed of the long head and short head. Both originate from the scapula and insert on the radius. The primary function of the biceps is elbow flexion and forearm supination, with a secondary role in shoulder flexion (Marieb and Hoehn, 2019). For optimal development, exercises must target both heads across their full range of motion.
Key Variables in Biceps Development
Muscle hypertrophy is driven primarily by mechanical tension, muscle damage, and metabolic stress (Schoenfeld, 2010). Each training modality—cables and free weights—produces these variables differently.
Mechanical Tension
Mechanical tension is created when a muscle contracts against a load. Both cables and free weights provide external resistance, but the nature of this resistance differs. Free weights operate under the influence of gravity, which means resistance is vertical and changes depending on joint angle. This creates a strength curve that can limit tension at certain points in the movement. For example, in a standing dumbbell curl, the resistance is highest when the forearm is perpendicular to the ground and lower at the top and bottom of the movement.
In contrast, cable machines offer constant tension throughout the range of motion because the resistance comes from the pulley system rather than gravity. A study by Signorile et al. (2002) showed that cable curls provided more uniform torque across the elbow joint angle compared to free weights. This suggests cables may offer superior mechanical tension across the entire range of motion.
Muscle Activation
Electromyography (EMG) studies measure muscle activation and offer insight into how effectively an exercise recruits target muscles. A study by Oliveira et al. (2009) compared EMG activity of the biceps during different curl variations and found that preacher curls and concentration curls (both typically performed with free weights) produced higher peak activation. However, another study by Signorile et al. (2002) demonstrated that cable curls yielded more consistent activation throughout the movement.
Thus, while free weights may offer higher peak activation, cables can deliver more sustained muscle engagement, potentially leading to greater hypertrophy over time due to prolonged time under tension.
Range of Motion (ROM)
Full range of motion is critical for hypertrophy because it increases time under tension and muscle fiber recruitment. Cables allow for a more adjustable line of resistance, enabling users to manipulate the angle and position to ensure full ROM and tension at both the start and end of the movement. Free weights, depending on form and joint angle, can sometimes fall short in this aspect. Pinto et al. (2012) found that training with a full range of motion led to significantly greater increases in muscle size compared to partial ROM.
Stability and Secondary Muscle Recruitment
Free weights challenge stabilizer muscles because the user must control the path of the load. This can be beneficial for overall functional strength. However, when the goal is pure biceps hypertrophy, this additional recruitment can be a drawback by diverting effort away from the biceps themselves. Schick et al. (2010) found that machine-based movements, which require less stabilization, resulted in greater target muscle activation compared to free weight alternatives. Therefore, cable exercises may isolate the biceps more effectively than free weights.
Exercise Variability and Specificity
Both cables and free weights allow for multiple biceps exercise variations. With free weights, standard options include dumbbell curls, hammer curls, preacher curls, and concentration curls. Cables offer variations such as high cable curls, low cable curls, rope curls, and single-arm cable curls. Cables excel in their ability to adjust the direction and angle of resistance, enabling more targeted stimulation of either the long or short head of the biceps.
For example, a study by Stauber et al. (2010) demonstrated that altering the angle of resistance in cable curls can shift emphasis between different muscle regions.
Overcoming Strength Curves
The resistance profile of an exercise is called its strength curve. Free weight exercises often have ascending or descending strength curves, meaning resistance is not constant. This can lead to portions of the lift being less effective.
In contrast, cables offer a linear resistance curve when properly aligned, ensuring that the biceps are engaged through the entire ROM. A study by Cronin et al. (2003) confirmed that linear resistance curves can be more effective for hypertrophy due to constant mechanical loading.
Convenience and Accessibility
Cables offer significant advantages in terms of setup and control, particularly for beginners or those with joint limitations. They allow for more precise adjustments, making them ideal for rehabilitation and hypertrophy-focused routines. Free weights, while more portable and accessible outside the gym environment, often require more coaching and technical skill to execute correctly.
Load and Progressive Overload
Progressive overload is essential for muscle growth. Free weights allow for more straightforward loading through standard weight increments. Cables, depending on the machine, may offer smaller increments and a smoother resistance profile, which can be both an advantage (for gradual progression) and a limitation (if max strength is the goal). A study by Mangine et al. (2015) found that heavy loading led to greater increases in muscle thickness, suggesting that free weights may offer an edge in absolute strength and mass gains when very heavy loading is applied.
Practical Recommendations
For bodybuilders and hypertrophy-focused athletes, cables offer superior isolation, constant tension, and variability. These traits make them excellent for maximizing biceps hypertrophy. However, free weights are indispensable for building foundational strength and peak activation. A combined approach may be optimal. A study by Gentil et al. (2013) showed that combining machine and free weight training produced greater hypertrophy than using either modality alone.
Conclusion
In the debate between cables and free weights for biceps development, neither is definitively superior in all contexts. Cables offer better constant tension, customization, and isolation, making them ideal for maximizing hypertrophy. Free weights deliver higher peak activation and improved functional strength. The most effective strategy may be to integrate both modalities into a periodized training plan that leverages the unique advantages of each.
References
Cronin, J.B., McNair, P.J. and Marshall, R.N. (2003) ‘Force-velocity analysis of strength-training techniques and load: implications for training and sports performance’, Journal of Strength and Conditioning Research, 17(1), pp.148–155.
Gentil, P., Soares, S., Pereira, M.C., Cunha, R.R., Martorelli, A.S. and Bottaro, M. (2013) ‘Effect of adding single-joint exercises to a multi-joint exercise resistance-training program on strength and hypertrophy in untrained subjects’, Applied Physiology, Nutrition, and Metabolism, 38(3), pp.341–344.
Mangine, G.T., Hoffman, J.R., Wang, R., Gonzalez, A.M., Townsend, J.R., Wells, A.J., Jajtner, A.R., Beyer, K.S., Bohner, J.D., La Monica, M.B. and Fukuda, D.H. (2015) ‘Resistance training intensity and volume affect changes in rate of force development in resistance-trained men’, European Journal of Applied Physiology, 115(11), pp.2381–2392.
Marieb, E.N. and Hoehn, K. (2019) Human Anatomy & Physiology. 11th edn. Boston: Pearson.
Oliveira, L.F., Matta, T.T., Alves, D.S., Garcia, M.A. and Vieira, T.M. (2009) ‘EMG amplitude of the biceps brachii during different curl exercises’, Journal of Sports Science & Medicine, 8(4), pp.498–502.
Pinto, R.S., Gomes, N., Radaelli, R., Botton, C.E., Brown, L.E. and Bottaro, M. (2012) ‘Effect of range of motion on muscle strength and thickness’, Journal of Strength and Conditioning Research, 26(8), pp.2140–2145.
Schick, E.E., Coburn, J.W., Brown, L.E., Judelson, D.A., Khamoui, A.V., Tran, T.T., Uribe, B.P. and Uribe, Z. (2010) ‘A comparison of muscle activation between a Smith machine and free weight bench press’, Journal of Strength and Conditioning Research, 24(3), pp.779–784.
Schoenfeld, B.J. (2010) ‘The mechanisms of muscle hypertrophy and their application to resistance training’, Journal of Strength and Conditioning Research, 24(10), pp.2857–2872.
Signorile, J.F., Zink, A.J. and Szwed, S. (2002) ‘A comparative electromyographical investigation of muscle utilization patterns using various hand positions during the lat pull-down’, Journal of Strength and Conditioning Research, 16(4), pp.539–546.
Stauber, W.T., Miller, G.R., Grimmett, J.G. and Knack, K.K. (2010) ‘Comparison of muscle adaptations in response to three different resistance-training regimens’, Journal of Applied Physiology, 108(5), pp.1245–1252.
