Department of Health and Kinesiology, Purdue University, West Lafayette, IN, United States.
Department of Health and Kinesiology, Purdue University, West Lafayette, IN, United States.
J Nutr. 2024 Jun;154(6):1803-1814. doi: 10.1016/j.tjnut.2024.04.001. Epub 2024 Apr 9.
Although experimental research supports that resistance training (RT), especially with greater dietary protein intake, improves muscle mass and strength in older adults, comparable research on tendons is needed.
We assessed the effects of a protein-rich diet emphasizing lean beef, compared with 2 control diets, on RT-induced changes in skeletal muscle and tendon size and strength in older women.
We randomly assigned women [age: 66 ± 1 y, body mass index (BMI): 28 ± 1] to groups that consumed 1) 0.8 g total protein/kg body weight/day from mixed food sources (normal protein control, n = 16); 2) 1.4 g/kg/d protein from mixed food sources (high protein control, n = 17); or 3) 1.4 g/kg/d protein emphasizing unprocessed lean beef (high protein experimental group, n = 16). Participants were provided with all foods and performed RT 3 times/wk, 70% of 1-repetition maximum for 12 wk. We measured quadriceps muscle volume via magnetic resonance imaging (MRI). We estimated patellar tendon biomechanical properties and cross-sectional area (CSA) using ultrasound and MRI.
Dietary intake did not influence RT-induced increases in quadriceps strength (P < 0.0001) or muscle volume (P < 0.05). We noted a trend for an RT effect on mean tendon CSA (P = 0.07), with no differences among diets (P > 0.05). Proximal tendon CSA increased with RT (P < 0.05) with no difference between dietary groups (P > 0.05). Among all participants, midtendon CSA increased with RT (P ≤ 0.05). We found a decrease in distal CSA in the 0.8 g group (P < 0.05) but no change in the 1.4 g group (P > 0.05). Patellar tendon MRI signal or biomechanical properties were unchanged.
Our findings indicated that greater daily protein intake, emphasizing beef, did not influence RT-induced changes in quadriceps muscle strength or muscle volume of older women. Although we noted trends in tendon CSA, we did not find a statistically significant impact of greater daily protein intake from beef on tendon outcomes. This trial was registered at clinicaltrials.gov as NCT04347447.
尽管实验研究支持阻力训练（RT），尤其是结合较高的膳食蛋白质摄入，可改善老年人的肌肉质量和力量，但类似的肌腱研究仍很有必要。
我们评估了富含蛋白质的饮食（强调瘦牛肉）与 2 种对照饮食相比，对老年女性 RT 引起的骨骼肌和肌腱大小及强度变化的影响。
我们随机分配女性（年龄：66±1 岁，体重指数（BMI）：28±1）到以下 3 组：1）混合食物来源的 0.8 g 总蛋白/kg 体重/天（正常蛋白对照组，n=16）；2）混合食物来源的 1.4 g/kg/d 蛋白（高蛋白对照组，n=17）；或 3）强调未加工瘦牛肉的 1.4 g/kg/d 蛋白（高蛋白实验组，n=16）。为参与者提供所有食物，并进行 12 周、每周 3 次、70%的 1 次重复最大量的 RT。我们通过磁共振成像（MRI）测量股四头肌肌肉体积。我们使用超声和 MRI 估计髌腱生物力学特性和横截面积（CSA）。
饮食摄入并不影响 RT 引起的股四头肌力量增加（P<0.0001）或肌肉体积增加（P<0.05）。我们注意到 RT 对平均腱 CSA 有影响的趋势（P=0.07），但不同饮食之间没有差异（P>0.05）。近端腱 CSA 随 RT 增加（P<0.05），但不同饮食组之间没有差异（P>0.05）。在所有参与者中，中腱 CSA 随 RT 增加（P≤0.05）。我们发现 0.8 g 组的远端 CSA 减少（P<0.05），但 1.4 g 组没有变化（P>0.05）。髌腱 MRI 信号或生物力学特性没有变化。
我们的研究结果表明，每日摄入更多的蛋白质，强调牛肉，不会影响老年女性 RT 引起的股四头肌力量或肌肉体积的变化。尽管我们注意到 CSA 的趋势，但我们没有发现从牛肉中摄入更多的每日蛋白质对腱结果有统计学意义的影响。本试验在 clinicaltrials.gov 注册，编号为 NCT04347447。
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