Shimizu Kazuhiro, Kimura Fuminori, Akimoto Takayuki, Akama Takao, Kuno Shinya, Kono Ichiro
Graduate School of Comprehensive Human Sciences, Doctoral Program of Sports Medicine, Tsukuba University, Ibaraki, Japan.
Med Sci Sports Exerc. 2007 Apr;39(4):593-8. doi: 10.1249/mss.0b013e318031306d.
The aim of this work was to assess the relationship in elderly subjects between free-living daily physical activity and mucosal immunity, especially salivary secretory immunoglobulin A (SIgA).
Elderly volunteers (114 men and 170 women) aged 71.3 +/- 0.3 yr (range: 65-86 yr) participated in this study. Resting saliva samples were collected in the morning. Saliva samples stimulated by chewing a sterile cotton ball at a frequency of 60/60 s were collected. The SIgA concentration was measured using enzyme-linked immunosorbent assay (ELISA), and the SIgA secretion rate was calculated. Free-living step count (steps per day), energy expenditure (kJ x kg(-1) x d(-1)), and activity durations (min x d(-1)) at specific intensity levels (inactive, light, moderate, and vigorous) were evaluated using an electric pedometer. The data obtained were stratified by pedometer-determined steps per day using quartiles (Q1-Q4) for distribution.
Elderly in quartiles showed step counts of 2962 +/- 94, 5118 +/- 62, 6832 +/- 59, and 9951 +/- 264 steps per day. Significant differences were found in the mean step count (P<0.0001), energy expenditure (P<0.0001), and activity duration (P<0.0001) with increasing pedometer-determined activity quartiles. Both SIgA concentration and SIgA-secretion rate were significantly higher for Q3 than for Q1 (P<0.05). Meanwhile, saliva flow rates showed no significant differences across quartiles.
These results suggest that a free-living daily physical activity level of approximately 7000 steps per day might be regarded as a moderate daily physical activity target for elderly people to improve mucosal immune function.
本研究旨在评估老年受试者自由生活状态下的日常身体活动与黏膜免疫之间的关系，尤其是唾液分泌型免疫球蛋白A（SIgA）。
114名男性和170名女性老年志愿者（年龄71.3±0.3岁，范围：65 - 86岁）参与了本研究。早晨采集静息唾液样本。以60/60秒的频率咀嚼无菌棉球刺激后采集唾液样本。使用酶联免疫吸附测定法（ELISA）测量SIgA浓度，并计算SIgA分泌率。使用电子计步器评估自由生活状态下的步数（每天步数）、能量消耗（kJ×kg⁻¹×d⁻¹）以及特定强度水平（不活动、轻度、中度和剧烈）下的活动时长（分钟×d⁻¹）。所获数据根据计步器确定的每日步数，采用四分位数（Q1 - Q4）进行分层分布。
处于四分位数的老年人每天的步数分别为2962±94、5118±62、6832±59和9951±264步。随着计步器确定的活动四分位数增加，平均步数（P<0.0001）、能量消耗（P<0.0001）和活动时长（P<0.0001）均存在显著差异。Q3组的SIgA浓度和SIgA分泌率均显著高于Q1组（P<0.05）。同时，四分位数间唾液流速无显著差异。
这些结果表明，对于老年人而言，自由生活状态下每天约7000步的日常身体活动水平可被视为改善黏膜免疫功能的适度日常身体活动目标。
