The bent-knee oblique v-up is an intermediate core exercise that targets the obliques and synergistically works several other core and leg muscles.
The inverse leg curl (aka bodyweight or Nordic hamstring curl) is useful for working your hamstrings in the absence of a leg-curling machine.
Use the stability ball leg curl to work your hamstrings in the absence of a leg-curling machine. To make it more difficult, perform it with one leg.
Use the spiderman push-up, a compound push exercise, to improve your balance and coordination, and build upper-body and core strength.
Depending on whether or not you flex your waist, the decline sit-up can either target your iliopsoas or your rectus abdominis.
The high bird dog plank is an excellent whole-body functional exercise for strengthening your core and improving your balance and coordination.
Targeting your iliopsoas, not your abs, the captain's chair leg raise is a hip flexion exercise. Your abs and obliques act as important stabilizers.
The one-leg push-up, which targets your lower pecs and obliques, puts your body out of balance, thus forcing the recruitment of more stabilizer muscles.
Work your iliopsoas and other hip flexors using the lying alternating leg raise, an isolation exercise. Your abs and obliques only act as stabilizers.
Use the weighted captain's chair leg and hip raise to strengthen your core and hip flexors. If you don't have a captain's chair, just hang from a bar.
Targeting your abs and obliques, the one-leg front plank is a unilateral bodyweight exercise useful for developing the strength and stability of your core.
Targeting your iliopsoas, not your rectus abdominis, the lying straight leg raise is an isolation pull exercise that activates all hip flexor muscles.