Opazo-Díaz Edgardo, Corral-Pérez Juan, Pérez-Bey Alejandro, Marín-Galindo Alberto, Montes-de-Oca-García Adrián, Rebollo-Ramos María, Velázquez-Díaz Daniel, Casals Cristina, Ponce-González Jesús-Gustavo
University of Cadiz, ExPhy Research Group, Department of Physical Education, Puerto Real, Spain.
Instituto de Investigación e Innovación Biomédica de Cádiz (INiBICA), Cadiz, Spain.
J Int Soc Sports Nutr. 2025 Dec;22(1):2455011. doi: 10.1080/15502783.2025.2455011. Epub 2025 Jan 29.
Impaired fat oxidation is linked to cardiometabolic risk. Maximal fat oxidation rate (MFO) reflects metabolic flexibility and is influenced by lean mass, muscle strength, muscle quality - defined as the ratio of strength to mass - and cardiorespiratory fitness. The relationship between these factors and fat oxidation is not fully understood. The aim is to analyze the associations of lean-mass, muscle strength and quality with fat oxidation parameters in young adults, considering the mediating role of VOmax.
A cross-sectional observational study. Eighty-one adults (50 males, 31 females; age 22.8 ± 4.4, BMI 25.70 ± 5.75, lean-mass 54.19 ± 8.78, fat-mass 18.66 ± 11.32) Body composition assessment by bioimpedance determine fat and lean-mass. Indirect calorimetry at rest and exercise was used for the calculation of fat oxidation. An incremental exercise protocol in a cycle ergometer with two consecutive phases was performed. The first to determine MFO consisted of 3 min steps of 15W increments with a cadence of 60rpm. The test was stopped when RQ ≥ 1. After 5 min rest, a phase to detect VOmax began with steps of 15W/min until exhaustion. Muscular strength was assessed by handgrip dynamometry and the standing longitudinal jump test. A strength cluster was calculated with handgrip and long jump adjusted by sex and age. Data were analyzed using multiple linear regression and mediation analyses.
Total lean-mass and leg lean-mass were not associated with MFO. Long jump, relativized by lean-mass and by leg lean-mass have a standardized indirect effect on MFO of 0.50, CI: 0.32-0.70, on MFO/lean-mass 0.43, CI:0.27-0.60 and MFO/leg lean-mass 0.44, CI: 0.30-0.06, which VOmax mediated, VOmax/lean-mass and VOmax/leg lean-mass, respectively (all < 0.01). The handgrip/arm lean-mass had an indirect effect of 0.25 (CI: 0.12-0.38) on MFO/leg lean-mass, with VOmax/leg lean-mass as the mediator ( < 0.01). The Cluster/lean-mass and Cluster/Extremities lean-mass have a standardized indirect effect on MFO/lean-mass (0.34, CI: 0.20-0.48) and MFO/leg lean-mass (0.44, CI: 0.28-0.60), mediated by VO2max/lean-mass and VO2max/leg lean-mass ( < 0.01).
Muscular strength and quality have an indirect effect on MFO mediated by VOmax. These findings suggest the importance of muscle quality on MFO.
脂肪氧化受损与心脏代谢风险相关。最大脂肪氧化率（MFO）反映代谢灵活性，并受瘦体重、肌肉力量、肌肉质量（定义为力量与质量之比）和心肺适能影响。这些因素与脂肪氧化之间的关系尚未完全明确。目的是分析年轻人中瘦体重、肌肉力量和质量与脂肪氧化参数之间的关联，并考虑最大摄氧量（VOmax）的中介作用。
一项横断面观察性研究。81名成年人（50名男性，31名女性；年龄22.8±4.4岁，体重指数25.70±5.75，瘦体重54.19±8.78，脂肪量18.66±11.32）通过生物电阻抗法进行身体成分评估以确定脂肪和瘦体重。通过静息和运动时的间接测热法计算脂肪氧化。在功率自行车上进行了一个包含两个连续阶段的递增运动方案。第一个阶段用于确定MFO，包括以15W的增量进行3分钟的步骤，踏频为60转/分钟。当呼吸商（RQ）≥1时停止测试。休息5分钟后，开始一个检测VOmax的阶段，以15W/分钟的增量进行直至 exhaustion。通过握力测力计和立定纵跳测试评估肌肉力量。计算一个根据性别和年龄调整的握力和跳远的力量聚类。使用多元线性回归和中介分析对数据进行分析。
总瘦体重和腿部瘦体重与MFO无关。以瘦体重和腿部瘦体重进行相对化处理的跳远对MFO的标准化间接效应为0.50，置信区间：0.32 - 0.70，对MFO/瘦体重为0.43，置信区间：0.27 - 0.60，对MFO/腿部瘦体重为0.44，置信区间：0.30 - 0.06，分别由VOmax、VOmax/瘦体重和VOmax/腿部瘦体重介导（均<0.01）。握力/手臂瘦体重对MFO/腿部瘦体重有0.25的间接效应（置信区间：0.12 - 0.38），以VOmax/腿部瘦体重作为中介（<0.01）。聚类/瘦体重和聚类/四肢瘦体重对MFO/瘦体重（0.34，置信区间：0.20 - 0.48）和MFO/腿部瘦体重（0.44，置信区间：0.28 - 0.60）有标准化间接效应，由VO2max/瘦体重和VO2max/腿部瘦体重介导（<0.01）。
肌肉力量和质量通过VOmax对MFO有间接影响。这些发现表明肌肉质量对MFO的重要性。
