Factors contributing to lower metabolic demand of eccentric compared with concentric cycling
Factors contributing to lower metabolic demand of eccentric compared with concentric cycling
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DOI：
10.1152/japplphysiol.00536.2016
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发表时间：
2017-10-01
影响因子：
3.3
通讯作者：
Nosaka, Kazunori
中科院分区：
文献类型：
--
作者：
Penailillo, Luis;Blazevich, Anthony J.;Nosaka, Kazunori
这项研究比较了相同工作输出下偏心自行车运动和向心自行车运动之间的肌肉肌腱行为、肌肉氧合和肌肉活动，以调查为什么偏心自行车运动中的代谢需求低于向心自行车运动。 11 名未经训练的男性（27.1 +/- 7.0 岁）以最大同心循环功率输出 (191 +/- 45 W) 的 65% 进行同心循环 (CONC) 和偏心循环 (ECC) 10 分钟 (60 rpm)，间隔 4 周。骑行期间，记录耗氧量 (O-2)、心率 (HR)、股外侧肌 (VL) 组织总血红蛋白 (tHb) 和氧合指数 (TOI)，并使用超声检查评估肌肉肌腱行为。记录 VL、股内侧肌 (VM)、股直肌 (RF) 和股二头肌 (BF) 肌肉的表面肌电图 (EMG)，并记录每次旋转时的骑行扭矩和膝关节角度。 ECC 期间的平均 O-2 (-65 +/- 7%) 和 HR (-35 +/- 9%) 低于 CONC，平均 TOI 较高 (16 +/- 1%)，但两次比赛之间的 tHb 相似。 ECC 期间的正循环峰值曲柄扭矩和负循环峰值曲柄扭矩比 CONC 期间更大（分别为 32 +/- 21 和 48 +/- 24%），但 CONC 和 ECC 期间踏板旋转期间的肌肉肌腱单位、束和肌腱组织长度变化相似。 ECC 期间的 VL、VM、RF 和 BF 峰值 EMG 振幅（分别为 24 +/- 15、22 +/- 18、16 +/- 17 和 18 +/- 9%）比 CONC 更小。这些结果表明，与向心自行车相比，偏心自行车的代谢成本较低，主要是由于每扭矩输出的肌肉激活水平较低。新的和值得注意的这项研究表明，在相同的工作量下，与向心自行车相比，偏心自行车的耗氧量较低，这是因为与向心自行车相比，偏心自行车期间主动肌和拮抗肌的肌肉活动较低。
This study compared muscle-tendon behavior, muscle oxygenation, and muscle activity between eccentric and concentric cycling exercise at the same work output to investigate why metabolic demand is lower during eccentric cycling than with concentric cycling. Eleven untrained men (27.1 +/- 7.0 y) performed concentric cycling (CONC) and eccentric cycling (ECC) for 10 min (60 rpm) at 65% of the maximal concentric cycling power output (191 +/- 45 W) 4 wk apart. During cycling, oxygen consumption (O-2), heart rate (HR), vastus lateralis (VL) tissue total hemoglobin (tHb), and oxygenation index (TOI) were recorded, and muscle-tendon behavior was assessed using ultrasonography. The surface electromyogram (EMG) was recorded from VL, vastus medialis (VM), rectus femoris (RF), and biceps femoris (BF) muscles, and cycling torque and knee joint angle during each revolution were also recorded. Average O-2 (-65 +/- 7%) and HR (-35 +/- 9%) were lower and average TOI was greater (16 +/- 1%) during ECC than CONC, but tHb was similar between bouts. Positive and negative cycling peak crank torques were greater (32 +/- 21 and 48 +/- 24%, respectively) during ECC than CONC, but muscle-tendon unit and fascicle and tendinous tissue length changes during pedal revolutions were similar between CONC and ECC. VL, VM, RF, and BF peak EMG amplitudes were smaller (24 +/- 15, 22 +/- 18, 16 +/- 17, and 18 +/- 9%, respectively) during ECC than CONC. These results suggest that the lower metabolic cost of eccentric compared with concentric cycling was due mainly to a lower level of muscle activation per torque output.NEW & NOTEWORTHY This study shows that lower oxygen consumption of eccentric compared with concentric cycling at the same workload is explained by lower muscle activity of agonist and antagonist muscles during eccentric compared with during concentric cycling.