O'Leary D D, Hope K, Sale D G
Department of Kinesiology, McMaster University, Hamilton, ON, Canada.
Can J Physiol Pharmacol. 1998 Jul-Aug;76(7-8):772-9. doi: 10.1139/cjpp-76-7-8-772.
Twitch contractions of the ankle dorsiflexors were evoked before and after 7 s of tetanic stimulation at 100 Hz in young women and men. Torque decreased more in men (18%) than in women (12%) during the tetanus. There was no gender difference in twitch peak torque potentiation over the 5-min post-tetanus. Potentiation was 42% (women) and 45% (men) at 5 s post-tetanus, and still present at 5 min (women 24%, men 25%). The immediate (5 s) shortening of twitch rise time was similar in women (14%) and men (13%), but during the 5-min men's rise time came to exceed whereas women's only approached pretetanus values (e.g., +9% vs. -1% at 5 min). The immediate decrease in half-relaxation time was also similar in women (24%) and men (22%); however, women's but not men's values remained less than pretetanus values for most of the 5-min period. Twitch rate of torque development increased similarly (75%) in women and men at 5 s, with no gender difference over 5 min. In contrast, rate of torque relaxation increased significantly only in men. Rate of torque development normalized to peak torque was similar in women and men pretetanus and increased similarly 5 s post-tetanus, but women had greater values through most of the 5-min post-tetanus. Normalized rate of torque relaxation was similar in women and men and not affected by tetanus. In the dorsiflexor muscles, young women and men show a similar amount and pattern of twitch force potentiation, but there are gender differences in time-related twitch contractile properties in the first 5 min after tetanus.
在年轻女性和男性中，在100Hz的强直刺激7秒前后诱发踝背屈肌的抽搐收缩。在强直收缩期间，男性的扭矩下降幅度（18%）大于女性（12%）。在强直收缩后的5分钟内，抽搐峰值扭矩增强没有性别差异。强直收缩后5秒时，增强幅度女性为42%，男性为45%，在5分钟时仍存在（女性24%，男性25%）。抽搐上升时间的即时（5秒）缩短在女性（14%）和男性（13%）中相似，但在5分钟内，男性的上升时间超过了之前，而女性仅接近强直收缩前的值（例如，5分钟时分别为+9%和-1%）。半松弛时间的即时缩短在女性（24%）和男性（22%）中也相似；然而，在5分钟的大部分时间里，女性的值仍低于强直收缩前的值，而男性则不然。抽搐扭矩发展速率在5秒时女性和男性的增加相似（75%），在5分钟内没有性别差异。相比之下，扭矩松弛速率仅在男性中显著增加。相对于峰值扭矩标准化的扭矩发展速率在强直收缩前女性和男性相似，在强直收缩后5秒时增加相似，但在强直收缩后的5分钟内，女性在大部分时间里的值更高。标准化的扭矩松弛速率在女性和男性中相似，且不受强直收缩的影响。在背屈肌中，年轻女性和男性表现出相似程度和模式的抽搐力增强，但在强直收缩后的前5分钟，与时间相关的抽搐收缩特性存在性别差异。
