I have been on the search for an app to measure distance for a long time...unpaid. I hate paying for apps although I will if its really compelling. Last week I found AirMeasure is part of Apple's new iOS 11. It looks like its made for interior decorators, measuring furniture height, room dimensions, etc. There is a mode to measure a person's height I have yet to try out.
I need to measure distance for 2 reasons: 6 Minute Walk Test, and then other distances such as classroom to cafeteria. I have been using reference values from Li, 2007, but recently came across a systematic review that pooled data from 12 studies. UNFORTUNATELY (and I know using caps is screaming), the authors pointed out that there was 159 meter difference between normative values and that the distance walked varied by culture.
The authors reported:
"Our systematic review clearly showed that the reference value for the walked distance can vary up to 159 meters, which is of great clinical importance if we consider the minimally significant difference already established in several adult populations, such as 32 meters for heart failure[29], 25 meters for coronary artery disease[30] and 30 meters for chronic pulmonary obstructive disease[31]. Unfortunately, no minimally significant difference is available for children and adolescents."
However, I was able to pull up another study that published norms by Geiger who published population based norms in 2007. These norms and other details are available online.
The lessons here? Be extremely careful about citing any normative value for the 6 Minute Walk test, and we need ularger population samples (anyone need a PhD or other research project?). For now, Geiger is sufficient for me...but I will continue to use it as a progress and outcomes measure.
Now back to the app, which was actually the reason I had planned to write this article: a few caveats I learned to use the app successfully...
1. Use the app to measure straight paths. When I tried measuring repeated loops, the app reset to zero.
2. Using the Point and Shoot feature, target a space that is several feet behind the starting point, and end several feet behind the finishing point (square floor tiles worked well). If I kept the camera focused focused on a person, it kept resetting to zero to measure dimensions of the person.
Perhaps when you experiment you will find a better way to use it, but for now this will be a huge time saver for me...and as for 6 Minute Walk Test norms,
References:
Cacau Lde AP, Santana-Filho VJde, Maynard LG, Neto MG, Fernandes M, Carvalho VO. Reference Values for the Six-Minute Walk Test in Healthy Children and Adolescents: a Systematic Review. Brazilian Journal of Cardiovascular Surgery. http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-76382016000500381. Accessed October 15, 2017.
Geiger, R, Strasak, A, Tremi, B, Gasser, K, Kleinsasser, A, Fischer, V, Geiger, H, Loeckinger, A, Stein, J. Six-Minute Walk Test in Children and Adolescents. Jour Pediatr. 2007: 395-399e2
Lammers AE, Hislop AA, Flynn Y, Haworth SG. The 6-minute walk test: normal values for children of 4–11 years of age. Archives of Disease in Childhood. http://adc.bmj.com/content/93/6/464. Published June 1, 2008. Accessed October 15, 2017.
Li AM, Yin J, Au JT, So HK, Tsang T, Wong E, et al. Standard reference for the six-minute-walk test in healthy children aged 7 to 16 years. Am J Respir Crit Care Med. 2007;176(2):174-80.