Do the hamstrings actually make the legs look bigger? The answer is yes. While the quadriceps on the front of the thigh are often the most visible muscle group, the hamstrings, located on the rear of the thigh, contribute significantly to the overall thickness, shape, and aesthetic appeal of the legs, especially when viewed from the side or back. Developing this posterior muscle group is a factor in achieving a balanced, strong, and visually impressive lower body.
Understanding Hamstring Anatomy and Function
The hamstrings are a group of three distinct muscles situated on the back of the thigh: the semitendinosus, the semimembranosus, and the biceps femoris (which has a long and a short head). All of these muscles, except for the short head of the biceps femoris, are biarticular. This means they cross both the hip joint and the knee joint.
This dual-joint crossing gives the hamstrings two primary functions. The first is hip extension, which involves moving the thigh backward (such as during the upward phase of a deadlift). The second function is knee flexion, the action of bending the knee (exemplified by a leg curl). Because the muscles originate at the pelvis and insert into the lower leg bones, their size and development directly influence the entire rear profile of the upper leg.
The Hamstring’s Role in Overall Leg Size
Developed hamstrings substantially contribute to the perception of larger, more complete legs, adding depth and thickness. They are estimated to represent approximately one-third of the total muscle volume in a well-developed thigh. This large volume of muscle mass on the posterior side creates a fuller, more rounded look to the entire upper leg.
When the hamstrings are well-trained, they create a noticeable “sweep” or outward curve from the glutes down toward the knee, particularly when viewed in profile. This depth counteracts the visual appearance of a thigh developed only by the quadriceps. A lack of hamstring development can leave the legs looking thin or flat from the side and back, even if the quads are large. Strong hamstrings also help create a clear, defined separation between the thigh and the gluteal muscles, enhancing the aesthetic shape of the entire posterior chain.
Effective Training Methods for Hamstring Hypertrophy
Maximizing hamstring size requires a training approach that targets both primary functions: hip extension and knee flexion. Relying solely on hip extension exercises will not fully develop all three hamstring muscles, necessitating a varied routine. A combination of movements is necessary because different exercises emphasize different parts of the muscle group.
Hip-extension movements primarily load the hamstrings in a lengthened position and are effective for hypertrophy, especially for the upper portion of the muscles. Examples include the Romanian Deadlift (RDL), which involves hinging at the hips, and the Good Morning exercise. Knee-flexion movements, such as the lying or seated leg curl, focus on contracting the hamstrings by bending the knee. Studies suggest that knee flexion exercises, particularly those performed in a hip-flexed position, can be superior for overall hamstring size increase, as they train the muscle at a longer length.
Achieving Balanced Lower Body Aesthetics
The most visually appealing and functionally robust legs result from balancing hamstring development with the size of the quadriceps and glutes. Focusing too heavily on the quadriceps without adequate posterior chain work leads to an imbalanced look, where the front of the thigh is significantly larger than the back. This disproportionate development can also increase the risk of injury and impact joint stability around the knee.
A balanced approach ensures that the legs look thick and powerful from all angles. A good guideline for training is to incorporate a roughly equal volume of exercises for the quadriceps and the hamstrings. By training both the anterior and posterior muscle groups effectively, hamstring development completes the look of a large, well-proportioned lower body.