Conclusions Leisure time physical activity may reduce the risk of chronic LBP by 11%–16 % .
Background There are plausible mechanisms whereby leisure time physical activity may protect against  low back pain ( LBP )  but there have been no quality systematic review s and meta-analyses of the subject .
Objective This review aims to assess the effect of leisure time physical activity on non-specific LBP .
Smoking, heavy physical work and low back pain: a four-year prospective study.
Data from a community-based four-year prospect i ve study were used to test the hypothesis that heavy physical work is a stronger predictor of  low back pain in smokers than in non-smokers . Of 708 working responders without low back pain during the entire year prior to 1990 , 562 ( 79 % ) completed a question naire four years later in 1994 . A job involving heavy lifting and much st and ing in 1990 was a strong predictor of low back pain in smokers four years later [ odds ratio ( OR ) = 5.53 , 95 % confidence interval ( CI ) = 1.93 - 15.84 , p < 0.01 ) after having adjusted for other job characteristics , demographic factors , emotional symptoms , physical exercise and musculoskeletal pain elsewhere . In non-smokers , having a job with heavy lifting and much st and ing was not associated with low back pain . One explanation may be that smoking leads to reduced perfusion and malnutrition of tissues in or around the spine and causes these tissues to respond inefficiently to mechanical stress
Conclusions Leisure time physical activity may reduce the risk of chronic LBP by 11%–16 % .
Background There are plausible mechanisms whereby leisure time physical activity may protect against  low back pain ( LBP )  but there have been no quality systematic review s and meta-analyses of the subject .
Objective This review aims to assess the effect of leisure time physical activity on non-specific LBP .