Published on in Vol 9, No 1 (2021): January
![Smartphone App (2kmFIT-App) for Measuring Cardiorespiratory Fitness: Validity and Reliability Study Smartphone App (2kmFIT-App) for Measuring Cardiorespiratory Fitness: Validity and Reliability Study](https://asset.jmir.pub/assets/2e97abf3ea7f1d154e92c87307c087b6.png 480w,https://asset.jmir.pub/assets/2e97abf3ea7f1d154e92c87307c087b6.png 960w,https://asset.jmir.pub/assets/2e97abf3ea7f1d154e92c87307c087b6.png 1920w,https://asset.jmir.pub/assets/2e97abf3ea7f1d154e92c87307c087b6.png 2500w)
1 Department of Physical Education and Sports, Faculty of Education, University of Balearic Islands, Palma, Spain
2 PROmoting FITness and Health Through Physical Activity Research Group, Department of Physical Education and Sports, Faculty of Sport Sciences, University of Granada, Granada, Spain
3 Chronobiology Research Group, Department of Physiology, Faculty of Biology, University of Murcia, Murcia, Spain
4 Ciber Fragilidad y Envejecimiento Saludable, Madrid, Spain
5 Department of Biosciences and Nutrition, Karolinska Institutet, Stockholm, Sweden