Tsuchiya Y, Sakuraba K, Ochi E
Graduate School of Medicine, Juntendo University, Tokyo, Japan - ochi @gen.meijigakuin.ac.jp.
J Sports Med Phys Fitness. 2014 Oct;54(5):651-7.
This study aimed to investigate the effects of eccentric contractions (ECs) of the biceps brachii muscle on bone metabolism markers.
Eight untrained subjects (20.0±0.5 years) performed 5 sets of 6 maximal ECs of the elbow flexors with a 2-min rest interval between each set. Blood samples were collected at 6 time points: before (Pre) ECs, immediately after (Post) ECs, and two hours (2 hours), 1 (day 1), 3 (days 3), and 5 days (days 5) after ECs. We measured the levels of the bone formation marker osteocalcin (OC) and the resorption marker tartrate-resistant acid phosphatase 5b (TRACP-5b). In addition, we measured the isometric tetanic torque and the levels of myoglobin (Mb), creatine kinase (CK), blood lactate, and insulin-like growth factor-1 (IGF-1).
The results showed 1) CK and Mb levels increased significantly by days 3 and 5 (P<0.05); 2) OC levels significantly decreased in Post and 2 hours (P<0.01) and TRACP-5b levels significantly increased in Post (P<0.01); 3) OC positively correlated with the total work output in Post, 2 hours, and days 5 (Post: r=0.79, P<0.05; 2 hours: r=0.82, P<0.01; days 5: r=0.79, P<0.05); and 4) TRACP-5b levels positively correlated with IGF-1 levels (r=0.69, P<0.01).
We conclude that a single bout of ECs of the biceps has a negative effect on bone metabolism in the acute phase.
本研究旨在探讨肱二头肌离心收缩（ECs）对骨代谢标志物的影响。
八名未经训练的受试者（20.0±0.5岁）进行5组每组6次的肘部屈肌最大离心收缩，每组之间休息2分钟。在6个时间点采集血样：离心收缩前（Pre）、离心收缩后即刻（Post）、离心收缩后2小时、1天（第1天）、3天（第3天）和5天（第5天）。我们测量了骨形成标志物骨钙素（OC）和骨吸收标志物抗酒石酸酸性磷酸酶5b（TRACP-5b）的水平。此外，我们还测量了等长强直扭矩以及肌红蛋白（Mb）、肌酸激酶（CK）、血乳酸和胰岛素样生长因子-1（IGF-1）的水平。
结果显示：1）第3天和第5天CK和Mb水平显著升高（P<0.05）；2）OC水平在离心收缩后即刻和2小时显著降低（P<0.01），TRACP-5b水平在离心收缩后即刻显著升高（P<0.01）；3）OC与离心收缩后即刻、2小时和第5天的总功输出呈正相关（离心收缩后即刻：r=0.79，P<0.05；2小时：r=0.82，P<0.01；第5天：r=0.79，P<0.05）；4）TRACP-5b水平与IGF-1水平呈正相关（r=0.69，P<0.01）。
我们得出结论，单次肱二头肌离心收缩在急性期对骨代谢有负面影响。
