Physical fitness and chronic low back pain: A case-control study including 517 individuals

Abstract

Deconditioning syndrome in chronic low back pain is admitted. It is comprised of low lombo-pelvic mobility, low muscular strength of the trunk, anxiety, depression and altered lifting capacity. However, profile of physical fitness, on the basis of energy expenditure, is controversial. The goal of the study was therefore to assess physical fitness in chronic low back pain patients, using markers of energy expenditure. This was a monocentric, retrospective case-control study, with prospective recording. Patients with chronic low back pain and healthy age- and sex-matched controls underwent bicycle exercise test, up to muscle exhaustion. Recorded energy variables were: duration of exercise in seconds, maximal power (P max) in watts, percentage of age-predicted maximum heart rate (HR max) and metabolic equivalents (MET). Pain intensity using the 0-100-VAS, pain duration and functional limitation using the Quebec scale were also assessed in chronic low back pain patients. Relationship between energy variables and clinical parameters was investigated using the Spearman correlation coefficient. Results of both groups were compared using the Student t -test. One hundred and ninety-two chronic low back pain patients (age 44 ± 8, ratio M/F 106/86, pain intensity 47 ± 19, pain duration 51 ± 57 months, Quebec 39 ± 16) and 325 healthy controls (44 ± 8, ratio M/F 199/126) were included. Duration of exercise (−0.23), P max (−0.21), and MET (−0.29) were related with the Quebec score in chronic low back pain patients ( P < 0.05). There was no other relationship between energy variables and clinical parameters. Energy variables were not different in both groups as they were globally considered. However, chronic low back pain patients with highest functional limitation (the fourth quartile of the Quebec scores) had lower duration of exercise (349 ± 134 vs. 431 ± 189), lower P max (129 ± 39 vs. 147 ± 49), and lower MET (7 ± 2 vs. 8 ± 2) than healthy controls ( P < 0.05). Physical fitness was not altered in the entire chronic low back pain population. However, physical fitness appeared to be decreased in chronic low back pain patients with highest functional limitation.