Purpose: To compare the effect of static holds and continuous passive motio
n on stiffness and force relaxation of the soft tissue structures resisting
ankle joint dorsiflexion. Methods: This study used a randomized repeated m
easures trial design. Twenty-four asymptomatic subjects (15 males and 8 fem
ales) with a mean age of 26 yr participated. A Kin-Com dynamometer was used
to measure the stiffness and force relaxation response of tissues about th
e ankle joint in response to a plantar flexor stretch. A comparison was mad
e of the response for a 1 x 60-s hold, 2 x 30-s holds, 4 x 15-s holds, and
continuous passive motion for 60 s. All subjects undertook all conditions.
The main outcome measures were 1) stiffness at the ankle joint as it moved
to 80% of the maximum range of dorsiflexion, and 2) the decrease in force a
c 80% of the maximum range of motion of the ankle joint. Results: Stiffness
was decreased significantly (P < 0.05) for the continuous passive motion c
ondition only. The mean magnitude of the decrease in stiffness was 16%. Acr
oss hold times, force decreased significantly (P < 0.05). Bonferonni contra
sts indicated that there was a significant difference (P < 0.05) between th
e continuous passive motion condition and all other hold conditions. There
were no significant differences (P > 0.05) between the 4 x 15-s, 2 x 30-s.
and 1 x 60-s holds. The magnitude of the decline in force was 10.5%. 21.5%.
21.7%, and 19% for the 0-, 15-, 30-, and 60-s holds, respectively. The gre
atest decreases in tension were achieved in the first 20 s of a hold. Concl
usion: If decreasing stiffness is a key aim of a stretching program, the fi
ndings indicate that continuous motion is more effective than holds. In con
trast, if relaxation of peak tension is the main aim, then holds are most e
ffective.