When it comes to hamstring training, the prone leg curl and standing leg curl are two staple machine exercises—but which one deserves a spot in your routine? The answer depends on your goals, fitness level, and muscle activation needs. Both target the hamstrings (biceps femoris, semitendinosus, semimembranosus) but differ in mechanics, stability, and secondary muscle engagement. Let’s break down their key differences, pros, cons, and who should prioritize each.
First, let’s clarify how each exercise works. The prone leg curl has you lie face-down on a machine, with your calves resting on a padded lever. As you curl your heels toward your glutes, your hamstrings contract concentrically, with your hips and lower back stabilized by the machine. The standing leg curl places you upright, holding a support bar, with one ankle hooked under a lever. You curl one leg back at a time, engaging your core and glutes to maintain balance while the hamstrings do the work.
Muscle activation is where the first key difference emerges. Prone leg curls isolate the hamstrings more effectively because the machine stabilizes your hips and lower back. This reduces compensation from the glutes and quads, making it ideal for targeting the hamstrings directly—especially the biceps femoris (the outer hamstring). Studies show prone leg curls elicit slightly higher hamstring activation than standing variations, thanks to this stability.
Standing leg curls, by contrast, are more functional. They require core engagement, balance, and glute activation to keep your body upright, mimicking real-world movements (like walking or running) where the hamstrings work alongside other muscles. They also tend to engage the semitendinosus and semimembranosus (inner hamstrings) slightly more, as the upright position changes the angle of muscle pull. For athletes or anyone focused on functional strength, standing leg curls offer added benefits beyond hamstring growth.
Now, let’s weigh the pros and cons. Prone leg curl pros: superior hamstring isolation, less balance required, great for beginners or those recovering from injury. Cons: can strain the lower back if form is poor (avoid arching your back), and less functional than standing curls. Standing leg curl pros: functional strength, core/balance engagement, better for inner hamstrings. Cons: more balance needed (harder for beginners), higher risk of compensation (swinging the leg) if you lift too heavy.
Who should choose which? If your goal is maximum hamstring hypertrophy (muscle growth) or you’re new to strength training, the prone leg curl is better. It lets you focus on the hamstrings without worrying about balance, allowing you to lift heavier with better form. If you’re an athlete, train for functional fitness, or want to engage more core and glutes, standing leg curls are the way to go. They build hamstring strength in a more natural movement pattern.
The bottom line: neither exercise is “better”—they’re complementary. For a well-rounded hamstring routine, include both. Do 3-4 sets of 8-12 reps for prone leg curls (focus on slow, controlled movements) and 2-3 sets of 10-15 reps per leg for standing leg curls (prioritize balance and form over weight). Adjust based on your goals: hypertrophy-focused routines can lean into prone curls, while functional routines can emphasize standing curls.
By understanding how each exercise targets your hamstrings, you can tailor your training to get the results you want—whether that’s bigger, stronger hamstrings or functional strength for daily life and sports.
