Surface-Knit and Reformulate CADENCE-Kids for Translation: The SKyRoCKeT Study

Specific Aims: The SKyRoCKeT Study will:

1. Expand CADENCE-Kids (1; NCT01989104) to innovatively surface-'knit' the age dimension through a continuous, unbiased-by-age, and physiologically-coherent age-cadence-log(MET) flexible surface approach without artificially-generated jumps between age ranges and with enhanced precision of cadence-intensity threshold estimates. This single surface will coherently transition between ages, borrow inter-age information, and be data-driven.
2. Reformulate CADENCE-Kids (1; NCT01989104) by providing age-specific cadence-intensity thresholds, calculated with enhanced precision for moderate and vigorous PA. Data will be objectively collected using a similar treadmill protocol to the R21-funded pilot study, with incrementally faster paces. Age-specific results will be compared to the pilot's age-range thresholds. A full running bout will now also be included. The investigators will concurrently collect cadence with direct observation and with multiple contemporary wearable technologies. Collecting cardiorespiratory fitness (CRF) and habitual PA data, the investigators will develop additional, innovative algorithms to predict relative intensity defined by lab-based indicators of oxygen uptake (%VO2peak, %VO2R), heart rate (%HRR, %HRmax), and rate of perceived of exertion (RPE) to facilitate computation of individually calibrated thresholds applicable to the free-living or habitual PA living condition. Investigators will assess differences in surfaces and cadence-intensity thresholds by sex and body mass index standard deviation scores (BMI SDS). Height- and/or leg-length-specific (hyper)surfaces will be explored as more precise alternatives to age.
3. Propel science forward innovatively through translation to over-ground walking. The investigators hypothesize that treadmill-set cadence-intensity thresholds will reliably translate and be useful for eliciting predictable metabolic costs during over-ground walking emblematic of free-living ambulatory behaviors.

Protocol/Procedures: 3 visits to the lab and 1 at home, free-living protocol

Screening: Screening questions will be completed online by potential participants (or their parents, where appropriate) and will take approximately 5 minutes. Following the initial recruitment web screener, potential participants (or their parents, where appropriate) will complete a telephone screener to confirm their responses. Potential participants (or their parents, where appropriate) will then attend a virtual or in-person orientation during which the study design procedures will be described in detail. Eligible potential participants who remain interested in the study will be scheduled for their first lab visit (with their parent/guardian if between 6-17 years of age).

Days of Testing in the Lab: Upon signing informed consent(s), participants must be fasted (no food for 4 hours before visit). Study procedures involving participants will be completed at the University of North Carolina at Charlotte. Visits 1 and 2 will be conducted at the Health Risk Assessment Laboratory (HRAL), and visit 3 will be conducted on an indoor track. Visit 1 will occur first and will be immediately followed by a week of free-living physical activity monitoring at home. Visit 2 will be completed once free-living, at-home monitoring is complete, and will be followed by visit 3.