SANTA CLARA, Calif. -- The San Francisco 49ers held their third practice of training camp Tuesday afternoon but for all intents and purposes it was really the first.

Training camp doesn't truly begin until the pads come on and the 49ers put theirs on for Tuesday's workout. It's a normal benchmark for any team that allows the real competition to begin and coaches to begin sorting out who can play and who can't.

But for the 49ers players who are still adjusting to practicing at coach Chip Kelly's patented overdrive speeds, it also meant more weight on their shoulders. Through the first couple of practices, the 49ers were undoubtedly tired at the end of the sessions but that fatigue kicked in sooner on Tuesday. Much sooner.

"Tempo is one thing, tempo with pads is a completely different thing," safety Eric Reid said. "We felt all of that today. It’s good for us as a defense. I think it’s obvious nobody else in the league is going to run at that pace so we should be very comfortable when it comes time to playing football.”

I asked Reid when he first started feeling the effects of the additional weight from the pads and he pointed to a timeframe that falls right at the beginning of practice.

"You notice it much earlier, like individual drills," Reid said. "You are doing all your drills, you have the extra weight, you feel it earlier."

Kelly's padded practices do not include live tackling sessions but do have live blocking, with "thud" tempo for the ball carrier in which the defender makes contact but does not take him all the way to the ground. Kelly wants his players to stay on their feet as much as possible.

Asked who he was most excited to see in pads, Kelly joked that it was all 90 players before pointing to the big men upfront.

"There’s a lot of those guys you really can’t tell until you get a chance and specifically offensively and defensive line-wise," Kelly said. "Because there’s been a lot of real cooperation there where, you know, Joe (Staley) may be able to jack a guy up and knock him back, but Joe understands that he’s going to take two steps and kind of pull out of it. The same thing with our D-Line, has done a great job. So, I think, hopefully things will iron out a little bit, but it’ll be a really big test because I think we’ve got some strength in our defensive line and I’ll be really impressed to see those guys when we get a chance to see them in full pads and see how they can disrupt things.”

While Kelly emphasizes tempo and efficiency in his practices, he also puts a premium on recovery. Which is why it's no coincidence that the 49ers will have their first day off of this training camp Wednesday.

-- As you'd probably expect, the defense appeared to be ahead of the offense in Tuesday's practice. Quarterbacks Blaine Gabbert and Colin Kaepernick both had passes batted down, including three for Gabbert, and there were more mental miscues like false starts, including a sequence in which the offense had two in a row during team drills. That could potentially be attributed to the fatigue of practicing at such speeds with pads on for the first time. Gabbert did connect with receiver Torrey Smith for a touchdown from about 40 yards out as Smith got behind Jimmie Ward on a post route.

-- Kelly said before practice that his coaching staff is still seeing how the two quarterbacks acclimate themselves and he expects the preseason games to be "huge" for determining a starter.

-- Not much change in terms of how the Niners aligned during practice though, as expected, Ray Ray Armstrong took his turn working at inside linebacker with the first unit. Armstrong had a couple of nice moments, including batting down a pass from Gabbert in team drills. Armstrong, Michael Wilhoite and Gerald Hodges have each taken a day so far in this camp and will continue that rotation moving forward.

-- The 49ers had their first round of one-on-one pass rush drills Tuesday. A few takeaways from that. ... Rookie guard Joshua Garnett had a couple of impressive blocks that showed off his powerful base, including one in which he was bull rushed, looked like he was going to get pushed back and firmly planted to hold his ground. ... While tackle Anthony Davis seemed to have a solid day overall, he did get beat soundly once by Aaron Lynch. ... Right tackle Trent Brown got physical with linebacker Ahmad Brooks on one of his reps, firmly planting Brooks on the ground. ... Linebacker Eli Harold showed his speed in getting around Colin Kelly but also was stood up on another rep. ... Left tackle Joe Staley also made it look easy against Brooks on one rep though intriguing young defensive lineman Ronald Blair beat him with a quick move to the inside later on. Blair showed up a few times later during team drills as well, getting the better of rookie tackle John Theus.

-- The 49ers are back at it Thursday after Wednesday's scheduled off day.