Accurate Quantification in Physiologic Phosphorus MR Spectroscopy

我们正在BLSA人群中进行广泛的动态31P运动研究，也从BLSA得出衰老、步行速度和其他结果指标的生物能量相关性。有氧体能和肌肉生物能量能力随着年龄的增长而下降；这种下降是否可以解释与年龄相关的步行速度放缓尚不清楚。我们假设，在简单和具有挑战性的运动测试中，肌肉能量和有氧能力是步行速度的独立相关因素，它们解释了在这些相同测试中观察到的与年龄相关的步行速度下降的原因。 使用磷磁共振波谱(31P-MRS)对126名(53名男性)参加巴尔的摩老龄纵向研究的126名参与者(平均年龄为72岁)进行了肌肉生物能量学评估，即运动后磷酸肌酸恢复率(PCr)，KPCr。分别进行4种步行任务，即普通步速6米150秒、快步速6米和400米，分别以最大耗氧量(最大摄氧量)作为有氧适应能力的评价指标。 我们发现，随着年龄的增长，所有步速、KPCR值和峰值VO2都会降低。与年龄、性别、身高和体重无关，KPCR值和峰值VO2都与快步速和长距离步行呈正相关，但只有峰值VO2和KPCR值与6米以上的正常步速显著相关。KPCR值和峰值VO2显著减弱了年龄和步速之间的关联，除了压力最小的6米常速步行任务外。 总体而言，使用31P-MRS评估的肌肉生物能量学与步行速度高度相关，并部分解释了与年龄相关的较差的快步和长步行走任务。

We are performing extensive dynamic 31P exercise studies in the BLSA population too develop bioenergetic correlates of aging, walking speed, and other outcome measures from the BLSA. Aerobic fitness and muscle bioenergetic capacity decline with age; whether such declines explain age-related slowing of walking speed is unclear. We hypothesized that muscle energetics and aerobic capacity are independent correlates of walking speed in simple and challenging performance tests and that they account for the observed age-related decline in walking speed in these same tests. Muscle bioenergetics was assessed as postexercise recovery rate of phosphocreatine (PCr), kPCr, using phosphorus magnetic resonance spectroscopy (31P-MRS) in 126 participants (53 men) of the Baltimore Longitudinal Study of Aging aged 2691 years (mean = 72 years). Four walking tasks were administeredusual pace over 6 m and 150 seconds and fast pace over 6 m and 400 m. Separately, aerobic fitness was assessed as peak oxygen consumption (peak VO2) using a graded treadmill test. We found that all gait speeds, kPCr, and peak VO2 were lower with older age. Independent of age, sex, height, and weight, both kPCr and peak VO2 were positively and significantly associated with fast pace and long distance walking but only peak VO2 and not kPCr was significantly associated with usual gait speed over 6 m. Both kPCr and peak VO2 substantially attenuated the association between age and gait speed for all but the least stressful walking task of 6 m at usual pace. Overall, muscle bioenergetics assessed using 31P-MRS is highly correlated with walking speed and partially explains age-related poorer performance in fast and long walking tasks.