Sit-ups and crunches are the most accessible ab exercises there are — no equipment, any floor. They're also surrounded by two persistent myths: that more is always better, and that enough of them will burn belly fat. Let's set realistic targets first.
Realistic daily targets
- Beginner: 2–3 sets of 10–15 reps, focusing on slow, controlled movement.
- Intermediate: 3–4 sets of 15–25 reps, or mix in variations — bicycle crunches, reverse crunches, leg raises.
- Advanced: higher volume helps endurance, but adding difficulty (decline, weighted, slower tempo) builds more strength than chasing 200 daily reps.
- Train abs 3–5 days a week — like any muscle, they grow between sessions, not during them.
The visible-abs truth
Sit-ups strengthen the muscles; they don't melt the fat covering them. "Spot reduction" has been tested repeatedly and doesn't hold up — visible abs come from overall body-fat reduction (diet plus total activity) layered over a strong core. The good news: the strength work still pays off in posture, back resilience, and performance long before any lines show.
Form cues that spare your neck and back
- Hands at your temples or across your chest — never yank your head forward.
- Curl up vertebra by vertebra; think "ribs toward hips", not "chest toward knees".
- Exhale on the way up, control the way down — dropping back fast wastes half the rep.
- Lower-back discomfort? Switch to crunches (shoulder blades off the floor only) or dead bugs and build up gradually.
An 18-a-day habit beats a 100-rep weekend
Consistency is the entire game with ab training, which is why SitUp - Workout DailyCrunch is built around a tiny daily dose — its public App Store subtitle is literally "18 sit-ups daily". The app counts reps automatically with iPhone sensors or Apple Watch, tracks your streak with widgets, and syncs to Apple Health. Eighteen controlled reps every day quietly outworks the occasional heroic session.