Being stressed is not usually a good thing. But when you're reviewing a high-profile smartwatch that touts stress-tracking as one of its most noteworthy new features, experiencing stress can be helpful. During the time I tested the Pixel Watch 2, I was going through a lot emotionally. I was maid of honor at our senior commerce editor's wedding, had a family funeral to think about and was getting updates on the results of my best friend's cancer diagnosis. Add to that the frenzy of Google's hardware launch event and a super tight deadline for this review, and my mental landscape became the perfect testing scenario for the Pixel Watch 2's body-response sensor. That's not the only new feature Google is bringing to its sophomore smartwatch.

This study investigates the effects of anthropometric attributes, biological sex, and posture on translational body kinematic responses in translational vibrations. In total, 35 participants were recruited. Perturbations were applied on a standard car seat using a motion-based platform with 0.1 to 12.0 Hz random noise signals, with 0.3 m/s2 rms acceleration, for 60 seconds. Multiple linear regression models (three basic models and one advanced model, including interactions between predictors) were created to determine the most influential predictors of peak translational gains in the frequency domain per body segment (pelvis, trunk, and head). The models introduced experimentally manipulated factors (motion direction, posture, measured anthropometric attributes, and biological sex) as predictors. Effects of included predictors on the model fit were estimated. Basic linear regression models could explain over 70% of peak body segments' kinematic body response (where the R2 adjusted was 0.728). The inclusion of additional predictors (posture, body height and weight, and biological sex) did enhance the model fit, but not significantly (R2 adjusted was 0.730). The multiple stepwise linear regression, including interactions between predictors, accounted for the data well with an adjusted R2 of 0.907. The present study shows that perturbation direction and body segment kinematics are crucial factors influencing peak translational gains. Besides the body segments' response, perturbation direction was the strongest predictor. Adopted postures and biological sex do not significantly affect kinematic responses.