Bicycle crunches: the EMG data, the technique, and the thing they will not do

The bicycle crunch earned its reputation from one study, and the study is better than most fitness claims get. A research team at the Biomechanics Lab at San Diego State University, led by Peter Francis and sponsored by the American Council on Exercise, put 30 men and women aged 20 to 45 through 13 common abdominal exercises while recording muscle activity with electromyography. Every exercise was normalized against a traditional crunch set at 100.

The bicycle maneuver ranked first for the rectus abdominis at 248 percent of a traditional crunch, and second for the obliques at 290 percent, behind the captain’s chair at 310 percent.

Two footnotes the fitness magazines dropped. The researchers noted that only exercises generating at least 25 percent more activity than a crunch count as notably more effective, so the reverse crunch at 109 is statistically the same as a crunch for the rectus abdominis. And the study also measured the rectus femoris, a hip flexor, because high activity there means the exercise is recruiting hip flexors rather than abs. On that measure the exercise ball crunch looked best overall, which is why Francis argued the ball was arguably the best exercise of the group despite ranking third.

how to do it so the numbers apply to you

EMG numbers come from people doing the movement correctly. Done badly, the bicycle crunch is a neck exercise with a hip flexor finish.

Lie on your back on a mat. Bring your knees up so your hips and knees are both near 90 degrees. Put your fingertips behind your ears, not laced behind your skull, because laced hands turn into a lever that yanks your head forward.

Press your lower back toward the floor and keep it there. This is the rule everything else depends on. Rotate your torso to bring one shoulder toward the opposite knee while that leg draws in and the other extends. The rotation comes from your ribs turning, not from your elbow reaching. Extending your arm across instead of turning your chest is the most common error and it removes most of the oblique work.

If your lower back lifts off the floor when a leg extends, raise that leg higher, closer to 45 degrees above the floor, until you can keep contact. Lower legs mean a longer lever and more demand on the hip flexors to hold the pelvis, which is exactly the recruitment pattern the researchers flagged as a sign of poor execution.

Exhale as you rotate, inhale as you switch. Make the movement match the breath rather than the other way around. Most beginners go roughly twice as fast as they should. The study used a two count in each direction, so about two seconds turning and two seconds returning. At that speed 10 reps per side is plenty, and fast sloppy reps at 30 per side are worth less than slow strict reps at 8.

what it will not do

The original version of this advice claimed bicycle crunches burn extra calories and raise body temperature. Technically true of any movement, and functionally irrelevant. A set of bicycle crunches lasting 40 seconds burns single digit calories.

The bigger claim is the one worth killing. Vispute and colleagues published a trial in the Journal of Strength and Conditioning Research in 2011 in which participants did seven abdominal exercises, two sets of 10 reps each, five days a week for six weeks. Compared with a control group, there was no significant reduction in abdominal subcutaneous fat, body weight, body fat percentage, or waist circumference. The training worked. Their abdominal endurance improved. The fat did not move.

Spot reduction does not happen, and that finding has held up across decades of similar studies. Visible abs come from lower total body fat, which comes from energy intake and overall activity, and the distribution of where you lose it is largely genetic. No number of repetitions changes that.

so what is the point of training abs

A reasonable case against dedicated ab work exists: heavy squats, deadlifts, carries, and overhead pressing already load the trunk hard, and plenty of strong people with visible abdominals have never done a crunch. I think that argument is mostly right for people who lift heavy three times a week.

Direct work still earns a place if you are not doing those lifts, if you want rotational strength for a sport, or if trunk endurance is your limiter on other movements. Two or three exercises, a few sets each, twice a week is sufficient. Rotation from the bicycle crunch, anti extension from a plank or dead bug, and something loaded like a cable or band press away covers the range.

Skip the gadgets. The Ab Rocker in that study measured 21 percent of a crunch for the rectus abdominis, meaning it was roughly 80 percent less effective than an exercise that costs nothing and needs a floor.