Iván Leonardo Duque

Maximal aerobic power in patients with chronic low back pain: a comparison with healthy subjects

The objective of the study was to compare the maximal aerobic capacity of patients with chronic low back pain with healthy asymptomatic controls matched for age, gender and level of physical activity at work and during sports activities. Reported data in the literature with respect to aerobic capacity in patients with chronic low back pain are not conclusive. Nevertheless, based on the assumption that chronic low back pain leads to deconditioning, physical training programs are widely used as a treatment. A total of 70 patients with chronic low back pain and 70 healthy asymptomatic subjects completed questionnaires regarding demographics and performed a graded maximal exercise test until exhaustion on a cycle ergometer. The maximal aerobic power was measured by indirect calorimetry. Heart rate, respiratory exchange ratio and blood lactate levels were also measured. The test was considered maximal when VO2max achievement criteria were obtained. VO2max values were compared among groups. The absolute and normalized for weight values of VO2max measured in patients with chronic low back pain were significantly lower than that of the control group. Independent comparison between men and women showed that absolute values of VO2max are also significantly lower in men and women with chronic low back pain. Women reached absolute and normalized for weight VO2max values significantly lower than those of men, both in chronic low back pain and control group. In conclusion, chronic low back pain patients, especially women, seem to have a reduced aerobic capacity compared to healthy asymptomatic subjects.

PHYSICAL DECONDITIONING IN CHRONIC LOW BACK PAIN

OBJECTIVE To establish the level of cardiorespiratory fitness and the rate of decrease in maximal aerobic capacity according to age in patients with chronic low back pain and compare these with normative data. DESIGN Prospective case series with historical controls. SUBJECTS/PATIENTS Seventy patients with chronic low back pain. METHODS A maximal cycle ergometer protocol was used to measure VO2max, heart rate, respiratory exchange ratio and blood lactate levels. RESULTS Seventy patients achieved absolute and normalized for weight VO2max values of 2.17 (standard deviation (SD) 0.65) l/min and 30.79 (SD 7.77) ml/kg/min, respectively. Absolute VO2max was poorly related to age in both men and women with chronic low back pain (r = -0.22 and r = -0.28, respectively). VO2max normalized for weight was also inversely related to age in both men and women (r = -0.36 and r = -0.42, respectively). The rate of VO2max decline between 20 and 59 years was -3.3 ml/kg/min/decade for the entire population and -1.2 and -5.4 ml/kg/min/decade in men and women, respectively. CONCLUSION The level of physical fitness of patients with chronic low back pain is comparable to the physical fitness of healthy, but poorly conditioned subjects. Patients with chronic low back pain show a VO2max decline with ageing that is slower than of active subjects.