Responses of candidate intensity measures to different mental and motor load levels using upper limb exergames in typically developing children and adolescents

Figures

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  Fig 1. A child plays the custom-made mental exergame using the Myro® while wearing a Shimmer® inertial measurement unit (IMU) at the wrist. The Myro® is a device with a 941x529 mm touchscreen. The therapist can adapt the device to the patient’s needs by adjusting the angulation, height, and work surface. The device responds to motion, pressure, and pulling, and patients can steer the games using their hands or objects that require different grasps. In therapy, the Myro® enables the training of gross and fine motor skills through video gaming. For this study, children steered the game using their dominant hand and fingers.

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  Fig 2. Study protocol. After the participant setup and a baseline measurement, the participant played two exergames in a randomized order. Each exergame consisted of a familiarization, a calibration, and a measurement, where the participant played each exergame at three intensity levels (i.e., “very easy”, “challenging”, and “very difficult”) in a randomized order. While playing, we measured the responses of the various intensity measures to each intensity level. After each intensity level, the participant answered the NASA-TLX questionnaire.

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  Fig 3. Mental exergame with the «owl with a brown beak» and «zombie with square glasses» targets. (A) Start screens before familiarization, calibration, and exergame with the target object (bottom) and its distractors (top). The start screen allowed the participant to memorize the target better. (B) Examples of three intensity levels for the «owl with a brown beak» and «zombie with square glasses»: a “very easy” intensity level (50% according to the calibrated output, left), a “challenging” level (100% of calibrated output, middle), and a “very high” intensity level (150% of calibrated output, right). The three intensity levels are compared here to visualize how the number of distractors changes. The participants performed the exergames on the large Myro® screen, where the targets and distractors were well recognizable.

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  Fig 4. Motor exergame. The participants had to hit the balloon with the nail. Once the balloon was hit, it reappeared in another position. The distance between the occurrence of two consecutive balloons is always between 60-80% of the participant’s range of motion. The time of reappearance depended on the calibration procedure and the intensity level. (N: Total number of balloons that appeared during the calibration).

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  Fig 5. Participant setup. (A) A chest strap with a Polar H10 Heart Rate Sensor tied tightly under the pectoral muscles measures heart rate variability. We assessed skin conductance using electrodes positioned on (B) the hypothenar side of the non-dominant hand and (C) the neck para-medial below the hairline. (D) An IMU sensor placed dorsally around the wrist of the dominant hand to measure activity counts. The blue box on the table is the MentalBioScreen K3 device for measuring skin conductance.

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  Fig 6. Results of the physiological measures. Boxplots with the descriptive statistics, i.e., median and interquartile ranges, and predicted values from the regression models in blue.

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  Fig 7. Results of the movement-based measures. Boxplots with the descriptive statistics, i.e., median and interquartile ranges, and predicted values from the regression models in blue.

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  Fig 8. Results of the patient reported measures. Boxplots with the descriptive statistics, i.e., median and interquartile ranges, and predicted values from the regression models in blue.