VoltraAb exercises: the 7 best moves and how often to do them
In two muscle-activity (EMG) studies, the ab-wheel roll-out worked the abs harder than crunches and sit-ups, and hanging knee raises were among the most effective moves tested [1] [2]. Train your abs like any other muscle, as part of strength training on 2 or more days a week [3].
Ab exercises make your abs stronger, but they don't burn the fat over them: six weeks of ab exercises, five days a week, didn't reduce belly fat or waist size [4].
What the studies found
- In 21 healthy adults, the ab wheel (roll-out, pike and knee-up), hanging knee-ups with straps and a reverse crunch on a 30-degree incline activated the abs the most of the exercises tested [1].
- In 18 adults, a roll-out and a pike on a Swiss ball reached 63% and 46% of a maximal contraction in the upper abs, more than most of the other exercises, which ranged from 7% to 53%, among them the crunch and the bent-knee sit-up [2].
- Lower-back muscle activity was low in every exercise, in both studies [1] [2].
- The bent-knee sit-up, the ab-wheel pike and knee-up, and the inclined reverse crunch also worked the hip flexors hard, which the authors say may be a problem for some people with low back problems [1].
The 7 ab exercises in Voltra
These are the ab exercises in Voltra's exercise library, with the rep range the app starts you on.
| Exercise | Equipment | Voltra's reps |
|---|---|---|
| Ab wheel rollout | Ab wheel | 6 to 12 |
| Hanging leg raise | Pull-up bar | 8 to 15 |
| Cable crunch | Cable machine | 10 to 20 |
| Decline sit-up | Decline bench | 10 to 20 |
| Russian twist | None | 15 to 30 |
| Plank | None | A timed hold |
| Side plank | None | A timed hold |
The roll-out and the hanging raises are the closest to the moves that scored highest in the studies above [1] [2]. Neither study tested the cable crunch, the Russian twist or planks.
How often, and how many
The WHO recommends muscle-strengthening activities that work all the major muscle groups on 2 or more days a week [3]; your abs can go on the same days. In the six-week study, 2 sets of 10 reps of 7 ab exercises, 5 days a week, improved ab endurance: the group that trained managed 47 curl-ups at the end, against 32 in the group that didn't [4].
Ab exercises and belly fat
On their own, ab exercises don't burn belly fat. In the same study, ab training changed none of body weight, body fat percentage, belly fat, waist circumference or the skinfolds over the abs, with everyone eating the same as before [4]. Belly fat goes down when you lose fat overall: see Can ab exercises burn belly fat?
How Voltra fits in
All seven are in Voltra's Exercise Library, each with a how-to video and the rep range above. Add any of them to a workout with Add exercise and log your sets as you go. Some of Voltra's programs already include planks.
Frequently asked
Do ab exercises burn belly fat?
Not on their own. Six weeks of ab exercises, five days a week, didn't reduce belly fat or waist size in a controlled study, though it did improve ab endurance.
How many days a week should I train abs?
Two or more, as part of your strength training: the WHO recommends muscle-strengthening activities on 2 or more days a week.
What is the most effective ab exercise?
In two EMG studies, roll-outs worked the abs harder than crunches and sit-ups, and hanging knee raises were among the most effective moves tested.
Are sit-ups bad for your back?
Sit-ups also work the hip flexors hard, which the authors of one study say may be a problem for some people with low back problems. Lower-back muscle activity was low in every exercise they tested.
Sources
- Escamilla RF, Babb E, DeWitt R, et al. (2006). Electromyographic analysis of traditional and nontraditional abdominal exercises: implications for rehabilitation and training. Phys Ther 86(5):656–671. Abstract.
- Escamilla RF, Lewis C, Bell D, et al. (2010). Core muscle activation during Swiss ball and traditional abdominal exercises. J Orthop Sports Phys Ther 40(5):265–276. Abstract.
- World Health Organization (2020). WHO guidelines on physical activity and sedentary behaviour. Recommendations for adults.
- Vispute SS, Smith JD, LeCheminant JD, Hurley KS (2011). The effect of abdominal exercise on abdominal fat. J Strength Cond Res 25(9):2559–2564. Abstract.
Sources checked on 1 October 2026.
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