Resumen de Gender Differences in Musculotendinous Stiffness and Range of Motion After an Acute Bout of Stretching

Katherine M. Hoge, Eric D. Ryan, Pablo B. Costa, Trent J. Herda, Ashley A. Walter, Jeffrey R. Stout, Joel T. Cramer

• The purpose of the present study was to examine musculotendinous stiffness (MTS) and ankle joint range of motion (ROM) in men and women after an acute bout of passive stretching. Thirteen men (mean ± SD age = 21 ± 2 years; body mass = 79 ± 15 kg; and height = 177 ± 7 cm) and 19 women (21 ± 3 years; 61 ± 9 kg; 165 ± 8 cm) completed stretch tolerance tests to determine MTS and ROM before and after a stretching protocol that consisted of 9 repetitions of passive, constant-torque stretching. The women were all tested during menses. Each repetition was held for 135 seconds. The results indicated that ROM increased after the stretching for the women (means ± SD pre to post: 109.39° ± 10.16° to 116.63° ± 9.63°; p <= 0.05) but not for the men (111.79° ± 6.84° to 113.93° ± 8.15°; p > 0.05). There were no stretching-induced changes in MTS (women's pre to postchange in MTS: -0.35 ± 0.38; men's MTS: +0.17 ± 0.40; p > 0.05), but MTS was higher for the men than for the women (MTS: 1.34 ± 0.41 vs. 0.97 ± 0.38; p <= 0.05). electromyographic amplitude for the soleus and medial gastrocnemius during the stretching tests was unchanged from pre to poststretching (p > 0.05); however, it increased with joint angle during the passive movements (p <= 0.05). Passively stretching the calf muscles increased stretch tolerance in women but not in men. But the stretching may not have affected the viscoelastic properties of the muscles. Practitioners may want to consider the possible gender differences in passive stretching responses and that increases in ROM may not always reflect decreases in MTS.