Examples of core training exercises. Bird dog: A, start position, B, lift opposite upper and lower extremities and hold, and C, lower to start. Repeat other combination. Prone plank: D, start position, E, add hip extension (sample variation), and F, side plank (sample variation). Dead bug: G, start position, H, lower opposite upper and lower extremities and hold, and I, repeat other combination (with or without ball). Half-knee rotation: J, start position (high), K, middle position, and L, end position. Repeat sequence.