Associations Among Smartphone Use, Activity Participation, and Hand Strength in University Students

Background: Hand strength supports occupational performance across daily activities, work, and leisure. Smartphone use has been linked to upper-extremity musculoskeletal symptoms, while activity participation involving repetitive hand use has been linked to greater grip/pinch strength. Few studies examine both together using objective usage data. This study examined associations among smartphone use, activity participation, and hand strength in university iPhone users. It was hypothesized that both smartphone use and activity participation would be associated with hand strength, and that activity participation would moderate the smartphone use-strength relationship. Methods: A cross-sectional correlational study was conducted with 166 undergraduate/graduate students at one U.S. university (2026). Eligible participants owned an iPhone X+ with Screen Time enabled. Data (single session) include demographics (age, sex, hand dominance, academic level, injury history, iPhone ownership length), grip/lateral pinch strength per hand in pounds (Jamar dynamometer/pinch gauge, ASHT protocol, mean of 3 trials), weekly smartphone use in hours from Screen Time across 6 apps, and participation in 6 activity domains (sports, physical activity, arts/crafts, tabletop, video games, instrument), coded as binary and weekly-hours. Smartphone use and strength variables were non-normally distributed (Shapiro-Wilk, p < .001); Spearman, point-biserial, and regression analyses were used accordingly. Results: Greater smartphone use was weakly, significantly associated with lower left-hand grip and pinch strength (rho = -.18, p < .03), concentrated among female and right-hand-dominant participants; no associations emerged for male or left-dominant participants. Sports participation was positively associated with all four strength measures (r = .26-.31), arts/crafts was negatively associated (r = -.30 to -.35), instrument playing was positively associated with pinch strength. Activity participation showed more consistent associations with hand strength than smartphone use in regression models; smartphone use did not independently predict strength once activity was controlled. An exploratory smartphone use x sports interaction predicted lower right-hand pinch strength (p = .024), interpreted cautiously given modest model-fit improvement. Conclusions: Activity participation, particularly sports and arts/crafts, was more consistently associated with hand strength than smartphone use, though associations were small-to-moderate and causality cannot be inferred. Reanalysis should use non-parametric methods given non-normal distributions; binary and hours-based measures diverged for some activities (e.g., tabletop), suggesting duration may matter beyond participation alone. Data may interest researchers studying technology use, activity engagement, and upper-extremity function in young adults.背景：手部力量支撑着日常活动、工作与休闲中的作业表现。既往研究表明，智能手机使用与上肢肌肉骨骼不适症状存在关联，而涉及重复性手部动作的活动参与则与更高的握力/捏力水平相关。目前鲜有研究借助客观使用数据同时探讨上述两类因素与手部力量的关联。本研究以美国某高校的iPhone用户为对象，考察了智能手机使用、活动参与与手部力量三者间的关联。本研究提出如下假设：智能手机使用与活动参与均与手部力量存在相关性，且活动参与会调节智能手机使用与手部力量间的关联。 方法：本研究针对美国某高校2026届的166名本科及研究生开展横断面相关性研究。合格参与者需持有iPhone X及以上机型且开启屏幕使用时长（Screen Time）功能。本次研究单次采集的数据包括：人口学信息（年龄、性别、利手、学业层次、损伤史、iPhone使用时长）；每只手的握力与侧捏力（单位：磅，采用Jamar握力计/捏力计，遵循美国手治疗师协会（American Society of Hand Therapists, ASHT）方案，取3次测试的平均值）；通过屏幕使用时长数据统计的6款应用每周总使用时长（单位：小时）；以及6类活动领域的参与情况，涵盖体育运动、体力活动、手工艺、桌面活动、电子游戏与乐器演奏，分别以二分类变量及每周活动时长两种形式编码。经夏皮罗-威尔克（Shapiro-Wilk）检验，智能手机使用与手部力量变量均不符合正态分布（p < 0.001），因此采用斯皮尔曼相关、点二列相关及回归分析方法开展统计分析。 结果：更高的智能手机使用时长与左手握力及捏力的降低呈微弱但显著的相关性（rho = -0.18, p < 0.03），该关联仅存在于女性及右利手参与者中，男性或左利手参与者未观察到此类关联。体育运动与四项手部力量指标均呈正相关（r = 0.26~0.31），手工艺活动则呈负相关（r = -0.30~-0.35），乐器演奏与捏力呈正相关。回归模型结果显示，活动参与相较于智能手机使用与手部力量的关联性更为稳定；在控制活动参与因素后，智能手机使用时长无法单独预测手部力量水平。探索性分析显示，智能手机使用时长与体育运动的交互项可预测右手捏力的降低（p = 0.024），鉴于模型拟合度提升幅度有限，需谨慎解读该结果。 结论：活动参与——尤其是体育运动与手工艺活动——相较于智能手机使用，与手部力量的关联性更为稳定，但关联强度仅为小至中等水平，且无法推断因果关系。鉴于数据不符合正态分布，后续重分析应采用非参数方法；部分活动（如桌面活动）的二分类参与变量与时长变量结果存在分歧，提示活动时长可能比单纯参与与否更具影响。本数据集可供研究青年人群技术使用、活动参与及上肢功能的学者参考。