First things first so this makes sense. Let’s find your Max Heart Rate. Subtract your age from 220. Whatever your number is, that is how many pulses per minute you should have at most when working out, at most. In other words, this is your Max Heart Rate. Then, if you are looking to address chronic pain, there is a lot of research showing that aerobic exercises decrease pain. Take 50-60% of your Max Heart Rate will improve your chronic pain syndromes. And if you exercise keeping a HR of 60-80% MaxHR, if you can tolerate it and have chronic pain, you will increase your fitness. Also, you should be able to perform from 15 to 60 minutes of aerobic exercises. Hence, the intensity should be light enough to allow the person to last this much time at this heart rate.
To measure your heart rate, you can: do it manually, use a pulse oxymeter, fitbit, or a digital watch such as an iwatch.
See the references below:
Physical activity and public health in older adults: recommendation from the American College of Sports Medicine and the American Heart Association. Nelson ME, Rejeski WJ, Blair SN, Duncan PW, Judge JO, King AC, Macera CA, Castaneda-Sceppa C. Med Sci Sports Exerc. 2007 Aug; 39(8):1435-45.
A comprehensive review of 46 exercise treatment studies in fibromyalgia (1988-2005). Jones KD, Adams D, Winters-Stone K, Burckhardt CS. Health Qual Life Outcomes. 2006 Sep 25; 4():67.
Vos T, Allen C, Arora M, et al. Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990–2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet. 2016;388(10053):1545.
Additional file 1: of Effects of aerobic exercise on pain and disability in patients with non-specific chronic low back pain: a systematic review protocol
dos Santos, I., Lunardi, A.C., de Oliveira, N.T.B. et al. Effects of aerobic exercise on pain and disability in patients with non-specific chronic low back pain: a systematic review protocol. Syst Rev 8, 101 (2019). https://doi.org/10.1186/s13643-019-1019-3