  Let $X$ be a regular linear continuous positively recurrent Markov process
with state space $\R$, scale function $S$ and speed measure $m$. For $a\in \R$
denote B^+_a&=\sup_{x\geq a} \m(]x,+\infty[)(S(x)-S(a)) B^-_a&=\sup_{x\leq a}
\m(]-\infty;x[)(S(a)-S(x)) We study some characteristic relations between
$B^+_a$, $B^-_a$, the exponential moments of the hitting times $T_a$ of $X$,
the Hardy and Poincar\'e inequalities for the Dirichlet form associated with
$X$. As a corollary, we establish the equivalence between the existence of
exponential moments of the hitting times and the spectral gap of the generator
of $X$.
