When deadlifting, is it a problem to have the shoulders in front of the bar?

As with all things; it depends on what you’re trying to accomplish.  So let's take a look at what’s happening during the lift before deciding if it’s acceptable for each individual person.  

In this example there are two main variables at play.  What is in front of the line of the bar and what is behind?  The further away a body part is from the midline of the bar the more work it has to do to reach full extension.  Leaning forward over the bar shortens the distance from the hips to the bar, reducing the amount of work required by the hip extensors to lift the weight.   Everything else behind the bar is likewise also exposed to less force.  So, each level of the lumbar spine now has less torque to deal with moving on up the thoracic spine until the point of the weight center.   On the front side of the bar the knee provides the driving vertical force. 

So here’s a question:  if the shoulders move back to the line of the bar and the knee stays the same distance in front of the bar, is it doing the same amount of work?   

The total mass in front of and behind the bar now becomes relevant.  The short answer is “no.”  Imagine doing a wall sit and how hard that is for the knees.  Now imagine doing a bodyweight squat.   You don’t feel nearly the same tension in the knee.  The reason is the shifted body weight of the torso serving as a counter force over the knee during the squat.  

Final question:  If the knee is doing less work then where is the extra force coming from?   Again, look at which major players are in front of the line.  As with all deadlifting form variations, the shoulder is the dynamic stabilizer connecting the bar to the body.  So the missing arrow in this picture is the line from the shoulder to the midline of the bar.  The lats are strongly firing along with the posterior deltoid to provide the missing force required of shooting that bar weight back towards the hips for full extension.   

Now the personalization of the lift starts to matter.   What is your goal for performing this lift?  Is your body doing this as a compensation movement?  If so, what’s not firing the way it should?  Does that change your ideal sets and reps?   You better believe all these variables matter!   As long as you’re performing smarter you can rest easy knowing your effort is translating to results that are important to you!