Foster has been dealing with a sore back and has not practiced at all during the Texans' training camp. He has also been dealing with a calf injury, but the back soreness is believed to be the root of his continued absence from practice.
The 26-year-old Foster has been a workhorse for Houston in recent seasons. He has 1,115 total touches over the last three seasons and has dealt with his fair share of injuries. Given his workload and advancing age, the latest development isn't completely out of left field.
Ben Tate, who is in a contract year, would be the next in line to get carries if Foster misses any significant time. After piling up over 1,000 total yards in 2011, Tate played in only 11 games in 2012 and mustered just 279 rushing yards.
Houston has some depth at running back, too, after signing both Dennis Johnson and Ray Graham as undrafted free agents back in the spring. Still, Kubiak probably isn't thrilled with having to rely on a Plan B at one of the most important positions in his offense.