Freudenthal suspension theorem

Statement
Let $$X$$ be a $$(n-1)$$-connected space having a nondegenerate basepoint $$x_0$$. Then the suspension homomorphism from $$\pi_q(X) \to \pi_{q+1}(\Sigma X)$$ is an isomorphism for $$q \le 2n - 2$$ and is surjective for $$q = 2n - 1$$.