Accurate Quantification in Physiologic Phosphorus MR Spectroscopy

我们正在BLSA人群中进行广泛的动态31 P运动研究，以开发衰老，步行速度和BLSA其他结果指标的生物能量相关性。有氧健身和肌肉生物能量能力随着年龄的增长而下降;这种下降是否解释了与年龄相关的步行速度减慢尚不清楚。我们假设肌肉能量和有氧能力是简单和具有挑战性的性能测试中步行速度的独立相关因素，并且它们解释了在这些相同的测试中观察到的与年龄相关的步行速度下降。 在巴尔的摩老龄化纵向研究的126名参与者（53名男性）中，使用磷磁共振波谱（31 P-MRS）评估肌肉生物能量学，即磷酸肌酸（PCr）的运动后恢复率（kPCr）。四种步行任务：正常步速6 m和150秒，快速步速6 m和400 m。另外，有氧健身评估为峰值耗氧量（峰值VO 2）使用分级跑台试验。 我们发现，所有的步态速度，kPCr和峰值VO 2随着年龄的增长而降低。与年龄、性别、身高和体重无关，kPCr和峰值VO 2均与快节奏和长距离步行显著正相关，但只有峰值VO 2而非kPCr与6 m以上的正常步态速度显著相关。kPCr和峰值VO 2大大衰减年龄和步态速度之间的关联，但在通常的步伐，最小的压力步行任务6米。 总体而言，使用31 P-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快速和长距离步行任务表现较差。

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.