In case someone with actual nonspecific low back pain read this thread I need to inform you.
Not being completely convinced by Dave's argument that increasing 1 RM deadlift will help you I have done a literature search.
First of I will mention that altough it is often claimed by physioterapists that tight hamstrings cause lower back pain,
there seem to be no evidence for this.
On the contrary a large study (n=600) (1) found that “Tight hamstring- or psoas muscles could not be shown to correlate to current back pain or to the incidence of back pain during the follow-up period.”
There are however several studies that shows that lower back pain is caused by poor endurance in lower back muscles.
The Biering-Sorensen test consist of maintaining a horizontal position with arms folded across the chest in a glute-ham raise machine for the longest possible time up to 240 seconds.
Several studies have found that subjects with nonspecific low back pain have significantly shorter holding time.
In a study (2) with 928 subjects Biering-Sørensen found:
"The main findings were that good isometric endurance of the back muscles may prevent first-time occurrence of LBT in men.
Weak trunk muscles and reduced flexibility/elasticity of the back and hamstrings were found as residual signs". That is to say isometric endurance in lower back is important, strength in lower back or flexibility is not.
Demoulin et al.(3) shows that maintaining the Biering–Sorensen position for less than 176 seconds, predicts low back pain within the next year and greater than 198 seconds predicts absence of low back pain.
As Dave mentions increasing maximum strength also increases endurance, at least to some extent.
The big question is if 3 minutes 18 secs on the Biering-Sorensen test is too long a time to be influenced by 1 RM deadlift.
I guesstimate a 1 RM deadlift to take 2 secs. Therefore the equivalent of a passing score on the Biering–Sorenson test would be ca. 100 deadlifts.
I doubt someone that only trains 5 reps or less can do a 100 deadlifts with say an empty bar regardless of their 1 RM deadlift.
I have also found some studies that shows that increasing strength in lower back by deadlifts reduces lower back pain: (4, 5). However these seems to be of lower quality.
The first one has only 30 subjects, the second one 70.
In the absence of conclusive knowledge I think the safest is to hedge ones bets.
That is one should increase 1 RM deadlift by doing sets of 5 at 85% of 1 RM but one should also increase static endurance in lower back by training specifically for this.
How to best do this I am not sure about. I think holding the horizontal position in the glute-ham raise machine for increasingly long times may be the best choice.
Doing the founder exercise may be a viable alternative in the absense of a glute-ham raise machine.
(1) Ann-Lisa Hellsing. Tightness of Hamstring- and Psoas Major Muscles. Upsala Journal of Medical Sciences. 1988.
Physical Measurements as Risk Indicators for Low-Back Trouble Over a One-Year Period.
Demoulin C, Vanderthommen M, Duysens C, Crielaard CM. Spinal muscle evaluation using the sorensen test: a critical appraisal of the literature. Joint Bone Spine. 2006;73(1): 43-50.
Welch et al. The effects of a free-weight-based resistance training intervention on pain, squat biomechanics and MRI-defined lumbar fat infiltration and functional cross-sectional area in those with chronic low back.
Aasa et al .Individualized Low-Load Motor Control Exercises and Education Versus a High-Load Lifting Exercise and Education to Improve Activity, Pain Intensity, and Physical Performance in Patients With Low Back Pain: A Randomized Controlled Trial. 2015.