Think of the world’s greatest athletes, like Chris Johnson, John Wall, Alex Ovechkin or Rafael Nadal. What do they have in common? They’re among the fastest players in their games. Speed is essential to success in sports, and it’s a quality that coaches look for when selecting athletes.
One of the best methods for developing speed is Resisted Sprints—sprints with some sort of weighted resistance to slow you down. Resisted sprints build lower-body power and cause more muscles to fire. Over time, you’ll be able to sprint much faster (especially when you run without resistance).
That said, you need to be cautious with this type of exercise—more is not better! Sprinting against too much weight changes your running form. You exert less force into the ground, have less range of motion at the hip and tend to lean forward. In short, too much resistance promotes bad running habits, which can carry over to unresisted sprinting.
Below are three resistance training drills that, if performed on your speed training days, will increase your sprinting speed. They  require no special equipment—just a few things that are available in any weight room. Follow the suggested weight limits to avoid developing bad running form.
Backpack Resisted Sprints
Wearing a backpack with weights inside is a great way to perform this exercise. (Note: use a cheap backpack, since the weights might rip the fabric.) Some things to watch out for when doing this:

• Use weights weighing no more than 10 to 15 percent of bodyweight
• Secure backpack tightly to prevent movement during sprints
• Start on backline of field in standing start position
• Explosively run straight, sprinting for specified distance
• Sets/Distance: 3-5×5-40 yards

Perform this drill for five or 40 yards, depending on the focus of your workout. Once you have sprinted the desired distance with the backpack, take it off and sprint another five to 10 yards without the resistance. Do this three to five times on your speed workout days.
Partner Resisted Sprints
This is a great partner drill for football players or other athletes working on first-step explosiveness.

• Assume starting position with partner standing in front of you
• Partner places his hands on your shoulders
• Sprint forward
• Partner backpedals, applying resistance to your shoulders
• Sets/Distance: 3-5×10-15 yards

Normally, this drill is only done for five yards. Once you reach five yards, your partner should move out of the way so that you can sprint unresisted for another five to 10 yards. Perform it three to five times during your speed workouts.
Towel Resisted Sprints
This is a variation of the above drill. For this drill, you need a partner and a large bath towel.

• Assume starting position
• Twist large bath towel and place it around your waist
• Partner stands behind you holding ends of towel
• Sprint forward
• Partner jogs behind you, holding onto towel
• Sets/Distance: 3-5×20-30 yards

Perform this drill for up to 20 yards. Once you have sprinted the desired distance, drop the towel and sprint another five to 10 yards. Perform this drill three to five times during your speed workouts.
Again, although Resisted Sprinting is effective, you need to be extremely cautious about the amount of resistance and maintain good form. If you find yourself leaning forward while doing the sprints, you have too much resistance!
Photo:  tylerknowshockey.com
John M. Cissik is the president of Human Performance Services, LLC, which helps athletics professionals solve their strength and conditioning problems. He has worked with all levels, produced four videos, written 10 books and more than 70 articles on strength and speed training. For more information, follow him on Twitter (@yourhpservices).