It’s no mystery that training for the NFL Scouting Combine is intense. The prospects are busting their butts to make a lasting impression on coaches and scouts. For some, it’s a make or break situation.

This sense of urgency was no more evident than during a workout we witnessed on the Malibu Sand Dunes, located just north of Malibu, California along Pacific Coast Highway.

Eight NFL prospects, including Su’a Cravens of USC and Kenny Clark of UCLA, performed an intense training session focused on lower-body explosive power at Proactive Sports Performance (Westlake Village, California) before making the 30-minute drive through the Santa Monica Mountains to the sand dunes.

From a distance, the dunes don’t look all that imposing. But once you get close, their scale is humongous. Based on our estimates, they are about 150 yards long with an incline of about 30 degrees.

RELATED: 7 Things Every Athlete Can Learn From NFL Combine Training

Only a few of the athletes had prior experience on the dunes. Cravens recalled the brutal difficulty of his first experience. The others had no idea what they were in for.

Josh Tuerpe, performance coach at Proactive, had the football players begin with a light jog up the dunes, then moved on to Shuffles and Broad Jumps. Although this was just a warm-up, it didn’t look easy—even walking up the hill was a challenge.

Once the warm-up was over, the real fun began.

The workout began with a Zigzag Sprint up the hill, which the players performed four times. Then Tuerpe lined up five cones 10 yards apart in a straight line, and the athletes formed two lines at the first cone. On Tuerpe’s cue, two of them raced to the cone and attempted to touch Tuerpe’s hand. This sequence was repeated every 10 yards to the final cone.

At the top of the course, the guys were absolutely gassed. As a group, they sat gasping for air before slowly walking down the hill for another set of Sprints—which they also repeated four times. It was exhausting just watching them.

There is an obvious conditioning element here. But also, training on the sand dune develops stride power and improves the technique needed to run a fast 40-Yard Dash.

“We come here to work specifically on the 40. We work on the first 10 to 15 yards, which is the acceleration phase,” explained Tuerpe. “It’s teaching them to stay down, because when you run [the dunes], you need to keep your chest down—just like when doing our drive phase.”

After finishing the races—which were highly competitive—the players moved to a sprint up to the entire hill, which did not look pleasant.

The guys were already gassed, and now they had to push themselves beyond the previous drills. For an athlete like Clark, who weighs over 300 pounds, this is no easy task. On the final sprint of the day, he was grinding up the hill with everything he had—egged on by cheers from the other athletes.

After they finished, the guys took a few minutes to recover before making their way down the hill. Some of them went for a dip in the ocean to cool off. Cravens decided to trek up the full hill to take in the scenery and reflect on the workout.

“The workout was brutal,” he said. “Going from a leg workout all the way to the dunes, doing as many reps as we did and competing against each other, that’s work you can’t get anywhere else. My legs feel like Jell-O. I want to sit down and take a nap.”

We don’t blame him.

RELATED: A Simple Core Routine Used by NFL Prospects