This study aimed to characterize the biomechanical stresses in the neck and shoulder, self-reported discomfort, and usability by different target distance or size during augmented reality (AR) interactions. In a repeated-measures laboratory-based study, 20 participants (10 males) performed three standardized AR tasks (3-dimensional (3-D) cube, omni-directional pointing, and web-browsing tasks) with three target distances (0.3, 0.6, and 0.9 m from each participant denoted by near, middle, far targets) for the 3-D cube and omni-directional pointing tasks or three target sizes: small (30% smaller than default), medium (default: 1.0 × 1.1 m), and large (30% larger than default) for the web-browsing task. Joint angle, joint moment, muscle activity, self-reported discomfort and comfort in the neck and shoulders; and subjective usability ratings were measured. The results showed that shoulder angle (flexion and abduction), shoulder moment (flexion), middle deltoid muscle activity significantly increased as the target distance increased during the 3-D cube task (p's < 0.001). Self-reported neck and shoulder discomfort significantly increased after completing each task (p's < 0.001). The participants preferred the near to middle distance (0.3–0.6 m) or the medium to large window size due to task easiness (p's < 0.005). The highest task performance (speed) was occurred at the near distance or the large window size during the 3-D cube and web-browsing tasks (p's < 0.001). The results indicate that AR interactions with the far target distance (close to maximum reach envelop) may increase the risk for musculoskeletal discomfort in the shoulder regions. Given the increased usability and task performance, the near to middle distance (less than 0.6 m) or the medium to large window size (greater than 1.0 × 1.1 m) would be recommended for AR interactions.

这项研究旨在通过增强现实（AR）交互过程中不同的目标距离或大小来表征脖子和肩膀上的生物力学应力，自我报告的不适以及可用性。在一项基于重复测量实验室的研究中，有20名参与者（10名男性）执行了三个标准化的AR任务（3维（3-D）立方体，全向指向和网络浏览任务），并具有三个目标距离（0.3，距离每个参与者分别为0.6、0.9 m（由近，中，远目标表示），用于3-D多维数据集和全向指向任务，或三个目标大小：小（比默认值小30％），中（默认值：1.0×1.1 m），并且较大（比默认值大30％）用于网络浏览任务。关节角度，关节力矩，肌肉活动，自我报告的脖子和肩膀不适感和舒适感；并评估了主观可用性等级。结果表明，在3-D立方体任务中，随着目标距离的增加，肩部角度（屈曲和外展），肩膀力矩（屈曲），中三角肌活动显着增加（p＜0.001）。完成每项任务后，自我报告的脖子和肩膀不适感明显增加（p <0.001）。由于任务的容易程度，参与者更喜欢近中距离（0.3-0.6 m）或中等到较大的窗口大小（p 's <0.005）。在3-D立方体和网络浏览任务期间，最高的任务性能（速度）发生在近距离或较大的窗口尺寸上（p（<0.001）。结果表明，AR与较远的目标距离（接近最大到达范围）的交互作用可能会增加肩部区域肌肉骨骼不适的风险。鉴于可用性和任务性能的提高，建议将AR交互使用近中距离（小于0.6 m）或中等大小的窗口（大于1.0×1.1 m）。