Aikawa Yuki, Wakasugi Yusuke, Fukuyasu Tomoya, Sasai Nobuaki, Yamashita Takenori, Ohtsuki Makoto, Hori Amane, Kioka Kazuki, Omi Naomi, Nakai Naoya, Higashida Kazuhiko
Department of Food and Nutrition, Tsu City College, Tsu, Japan.
Faculty of Health Science, Suzuka University of Medical Science, Suzuka, Japan.
J Appl Physiol (1985). 2025 Jul 1;139(1):14-26. doi: 10.1152/japplphysiol.00978.2024. Epub 2025 May 23.
Low energy availability refers to a state where the body cannot provide sufficient energy to maintain essential physiological functions due to excessive exercise and inadequate energy intake. In athletes, low energy availability impairs bone parameters but may assist muscle adaptation from endurance training. This study was conducted to explore the effect of the combination of running and energy restriction (ER) on bone parameters and muscular endurance adaptations in young female rats. Seven-week-old female rats were divided into four groups: ) sedentary and ad libitum feeding (AL); ) voluntary wheel running and AL; ) sedentary and ER; and ) voluntary wheel running and ER. The experimental period was 11.5 wk. The ER groups were fed a 28% restricted diet compared with the sedentary and AL group. Our results demonstrated that the combination of running and ER decreased the body weight, uterus weight, plantaris and soleus muscle weight, bone mineral density of femur, tibia, and lumbar, and trabecular number of tibia. However, running increased the cross-sectional area (CSA) of type I and IIA fibers and the mitochondrial proteins levels in plantaris muscle under both AL and ER conditions. In the soleus muscle, running exerted no significant main effects on the transition to the myofiber type. ER did not affect the transition to the myofiber type and the mitochondrial protein levels in plantaris and soleus muscles. Our study reveals that the combination of running and ER impairs bone parameters; however, running induces endurance adaptations of plantaris muscle under both AL and ER conditions in young female rats. Low energy availability impairs bone parameters but may assist muscle adaptation from endurance training. Our study demonstrated that the combination of running and energy restriction (ER) impaired bone mineral density and bone microarchitecture in young female rats. However, running increased the cross-sectional area of type I and IIA fibers, and the levels of mitochondrial proteins in plantaris muscle under both ad libitum feeding and ER conditions in young female rats.
低能量可利用性是指由于过度运动和能量摄入不足，身体无法提供足够能量来维持基本生理功能的一种状态。在运动员中，低能量可利用性会损害骨骼参数，但可能有助于肌肉从耐力训练中适应。本研究旨在探讨跑步与能量限制（ER）相结合对年轻雌性大鼠骨骼参数和肌肉耐力适应性的影响。将7周龄雌性大鼠分为四组：（1）久坐不动且自由进食（AL）；（2）自愿轮转跑步且自由进食；（3）久坐不动且能量限制；（4）自愿轮转跑步且能量限制。实验期为11.5周。与久坐不动且自由进食组相比，能量限制组给予28%的限制饮食。我们的结果表明，跑步与能量限制相结合降低了体重、子宫重量、跖肌和比目鱼肌重量、股骨、胫骨和腰椎的骨矿物质密度以及胫骨的骨小梁数量。然而，在自由进食和能量限制两种条件下，跑步均增加了跖肌中I型和IIA型纤维的横截面积（CSA）以及线粒体蛋白水平。在比目鱼肌中，跑步对肌纤维类型转变没有显著的主要影响。能量限制对跖肌和比目鱼肌的肌纤维类型转变以及线粒体蛋白水平没有影响。我们的研究表明，跑步与能量限制相结合会损害骨骼参数；然而，在年轻雌性大鼠中，无论自由进食还是能量限制条件下，跑步均可诱导跖肌的耐力适应性。低能量可利用性会损害骨骼参数，但可能有助于肌肉从耐力训练中适应。我们的研究表明，跑步与能量限制相结合会损害年轻雌性大鼠的骨矿物质密度和骨微结构。然而，在年轻雌性大鼠中，无论自由进食还是能量限制条件下，跑步均增加了跖肌中I型和IIA型纤维的横截面积以及线粒体蛋白水平。
