What if improving your running is not only about logging more miles, but also about how your legs handle each step? A new study suggests that pairing heavy strength moves with explosive jumps can make teenage distance runners more efficient at faster paces, meaning they use less oxygen to hold the same speed.
In an eight-week experiment, researchers led by Shiping Yu, with Shengqing Zhou, Daibin Peng, and Dongli Jie, tested this approach in 32 male runners ages 16 to 18 from provincial teams in China. The work involved Wuhan City Polytechnic and Wuhan Sports University, and the paper is available at doi.org/10.3389/fphys.2025.1718150.
What the team actually did
The runners were split into two groups of 16 and kept their normal endurance work, averaging about 28 miles a week. Three times a week, they added strength sessions that lasted about an hour, and coaches supervised every session to keep technique consistent.
Before and after the program, the athletes ran on a treadmill at about 7.5, 8.7, and 9.9 miles per hour while researchers measured oxygen use, heart rate, and blood lactate. They also tested max squat strength and several jumps, which are common ways to gauge lower-body power.
Why “running economy” matters
“Running economy” is basically the body’s energy bill for a steady pace, often tracked by how much oxygen you need each minute. If two runners have similar aerobic fitness, the one with the lower oxygen cost can usually hold a hard pace longer, especially late in a race when legs start to feel heavy.
A 2015 review in Sports Medicine Open explains that running economy can separate athletes who look similar when you only compare maximal oxygen uptake, sometimes called “VO2 max.” That overview is here, doi.org/10.1186/s40798-015-0007-y.
Complex training in plain terms
The “complex training” group did a heavy resistance exercise and then, after a short rest, performed a jump using a similar movement pattern. Think squats followed by box jumps, or a loaded hex bar pull followed by quick hops.
Plyometrics, the jump-based part of the plan, are drills where the legs act like springs, storing energy on landing and releasing it on takeoff. In practical terms, that can train the body to produce force quickly, which matters when you surge, sprint the final straightaway, or simply try not to lose form. A 2018 trial in Medicine and Science in Sports and Exercise reported that plyometric training alone can improve running economy in post-pubertal teen endurance athletes, doi.org/10.1249/MSS.0000000000001543.
The traditional group lifted the same main exercises but skipped the jump work, adding extra sets to keep training volume similar. The study followed guidance aligned with youth resistance training recommendations, including the 2014 international consensus statement in the British Journal of Sports Medicine, doi.org/10.1136/bjsports-2013-092952.
The biggest change showed up at faster speeds
After eight weeks, the complex training group reduced the oxygen cost of running at all three treadmill speeds, with the largest shifts at the faster paces. At about 9.9 miles per hour, their oxygen use dropped from roughly 27 to 23 milliliters per pound per minute, which is about a 15 percent improvement in efficiency.
The traditional lifting group improved a bit at the two slower speeds, but the changes were smaller overall. At the fastest pace, their oxygen cost barely moved, and the study reported a clear gap between the two groups.
Blood lactate, a chemical that tends to rise when the body relies more on fast energy, also fell more in the complex training group. At about 8.7 miles per hour, their lactate level dropped from about 3.3 to 3.0 millimoles per liter, while the traditional group stayed about the same.
More spring in the legs
Both groups got stronger on the squat, which makes sense given they were training it regularly. In the complex training group, the average max squat climbed from about 159 pounds to about 186 pounds, while the traditional group rose from about 157 pounds to about 181 pounds.
The jump tests leaned in favor of the complex training group, especially for movements that reward quick takeoff. Their countermovement jump rose from about 12.6 inches to about 14.5 inches, and their drop jump went from about 12.9 inches to about 15.0 inches, while the traditional group saw smaller gains.
One standout metric was the “reactive strength index,” a score that blends how high an athlete jumps with how quickly they leave the ground. That score rose about 26 percent in the complex training group, compared with about 8 percent in the traditional group.
What could be driving the efficiency boost
So why would jumping after heavy lifting help a distance runner? One idea is that the heavy set “primes” the nervous system, and the explosive move that follows teaches the body to turn that readiness into faster force, a concept coaches sometimes call “post-activation performance enhancement.”
Over time, this may help the legs waste less energy with each landing and push-off, like a spring that snaps back more cleanly. A 2017 systematic review in Sports Medicine reached a similar conclusion for endurance athletes and is here, doi.org/10.1007/s40279-016-0604-z.
What young athletes and coaches can take from this
For coaches, the message is not that every teen runner needs to chase bigger numbers in the weight room. It is that, for many athletes, a carefully supervised mix of strength and jump work may build efficiency and speed-related power without cutting into endurance training.
There are still limits to keep in mind, since the runners were all male, the program lasted eight weeks, and the training was monitored closely, so results may differ in other groups or settings. A 2020 position statement in Pediatrics says good supervision and gradual progression are key, doi.org/10.1542/peds.2020-1011.
The main study has been published in Frontiers in Physiology.
