By Bob Townsend, CSCS.
Life Time Endurance Coach & Personal Trainer

Can simultaneous plyometric and endurance training produce significant in running economy -- hence running performance?

Typically, long-slow distance training has been the preferential training method for improving running economy. Traditionally VO2 max has been considered the best predictor of endurance performance. Running economy is now thought to be a better predictor. Many runners still believe that strength training won't do anything for them. Numerous studies have shown that strength training reinforces muscles, tendons, and ligaments, reduces injury rates and improves running form. I believe that lower body plyometric exercises can improve running economy. This increase in economy will then increase running performance, resulting in faster race times.

Strength and endurance training represents distinctly different adaptive responses. Typically strength training involves high-resistance, low-repetitions to increase the force output. In contrast, endurance training utilizes low-resistance, high-repetition exercises to increase VO2 max.1 Strength training has minimal effect on VO2 max. It may be possible that stronger athletes are more efficient or economical in their movements, leading to enhanced endurance capabilities. 2

In a 1998 study by Dr. R.C. Hickson at the University of Illinois -- Chicago showed that by adding strength training to an endurance training program improved endurance performance. Subjects in the study increased their time to exhaustion by 13 percent. In another study conducted by Ron Johnston of the University of New Hampshire, Department of Kinesiology in 1994 found that running economy improved significantly with strength training. It is suggested that some fatigue resistance can be improved through strength training. Strength training has been shown to reduce the amount of muscle activation for a given load.2 Runners may improve endurance performance via a resistance-training program. Strength training may actually improve endurance capacity.1

If the studies suggest that strength training can enhance endurance performance, can it be presumed that plyometric exercises would improve running economy? Plyometrics is defined as exercises that allow the muscle to reach maximum force in as short time as possible.3 A practical definition of plyometrics is a quick powerful movement using a pre-stretch that involves the stretch shortening cycle (SSC).4 Muscle elasticity is an important factor in understanding how the SSC can produce more power than simple concentric contraction. The faster a muscle is stretch or lengthened, the greater the concentric force after the stretch. The result is a more forceful movement for overcoming the inertia of an object, a runners own body weight.3

Plyometrics trains the muscle to reach maximum force in as short of time as possible. The ability to combine speed and strength is what we refer to as power.5 By using plyometrics to develop the SSC, athletes are better able to accelerate their bodies and generate greater force therefore improving performance.6 The SSC function remains important in endurance running.7

Speed and strength are integral components of fitness found in varying degrees in virtually all athletic movements. For many years athletes have sought to improve power in order to enhance performance.8

What basic factors allow you to run faster? Biometrically, it's the combination of increased stride rate and/or stride length -- the more steps (leg turnover) and/or take bigger steps. To increase stride rate requires an increase in power. To increase stride length requires an increase in strength.

Explosive strength training may lead to specific neural adaptations, such as increased rate of motor unit activation, whereas muscle hypertrophy remains smaller than during typical heavy resistance training.9

There are basically two ways to increase a muscles' force:

1. increase the rate at which a motor unit is stimulated
   and/or
2. increase the number of motor units that are activated

Plyometrics training increases these two factors affecting force production and speed of that force production.5 A program of plyometrics and weight training will improve leg strength and power.10

In a six-week regime of ploymetric training of 18 regular, but not highly trained distance runners, concluded that plyometric training improved running economy.11 Running economy improved significantly in the endurance and strength-trained group. The finding suggests that strength training, when added to an endurance-training program, improves running economy.12

The fastest runners are those who spend less time on the ground, which is greatly determined by the runners' strength and power. SSC training will prepare the athlete to run faster through drills designed to work the specific muscles involved in fast locomotion.13

For runners, power usually means longer stride length. Merely lengthening the stride length by one inch -- shortens the marathon by about 1 kilometer (.62 miles). This 1 km improvement would trim an average of 3-6 minutes from a marathon finishing time.14

Numerous studies have established the effectiveness of plyometric drills in improving power and speed. One study showed that simultaneous sport-specific explosive-strength training and endurance training may also improve 5K running performance of well trained endurance athletes.9

The National Strength and Conditioning Association Position Statement on Plyometric Exercises is that:

1. The stretch-shortening cycle is essential in the performance of most competitive sports, particularly those involving running . . .
2. A plyometric exercise program . . . can improve performance in most competitive sports.

As concluded in the studies, resistance strength training undeniably benefits the endurance runner. Plyometics, being a high intensity form of resistance training, but different in that traditional resistance training is not optimal at delivering sport-specific speed and power. Studies have suggested that strength and power in the lower body may be more important than previously thought. It is possible that with lower body plyometric exercises, runners could achieve greater propulsion for the same or less energy expenditure.

Recommendations
It would seem that in trained runners, focused on the development of leg strength and power may further improve running performance. Plyometrics requires the muscle to reach maximal force in the shortest possible time. Lower body plyometric exercises emphasize quick foot movement and the ability to get off the ground quickly. Thus, lower body plyometric exercises could be appropriate for the endurance runner who wishes to produce the maximal amount of muscular force in a short amount of time and minimize contract with the ground. Many runners and coaches are constrained by tradition in training programs. Runners and coaches that are more open-minded break tradition and seek out innovative training methods. These runners and coaches who perform complex training methods may enjoy the best results from their training.

Bob is a veteran triathlete, a two time Ironman finisher with 10 years of experience, and nearly 30 years of running experience. He is a certified traithlon coach by USA Traithlon and a certified cycling coach by USA Cycling. Bob also holds certifications from the National Strength and Conditioning Association as a Certified Strength & Conditioning Specialist and a Personal Training certification from American College of Sports Medicine. For more information about Bob, click here.

References

1. Burne, Andrew. Concurrent Strength and Endurance Training." Curtin University of Technology School of Physiotherapy. 2000
2. Carlock, John, Meg Stone. "Maximum Strength & Stretch Training A Relationship to Endurance."
3. Chu PhD, Donald. Jumping into Plyometrics. Champaign, IL: Human Kinetics 1998
4. Potach, David and Donald Chu. Essentials of Strength Training and Conditioning. Thomas R. Baechle and Roger W. Earle, Editors. Champaign, IL: Human Kinetic 2000
5. Kutz, Matthew R. "Theoretical and Practical Issues for Plyometric Training" National Strength and Conditioning Association's Performance Training Journal. 2.2:10-12
6. Robberds, C. "Power Development" Faccioni Publications
7. Harrison, Andrew J., Sean P. Keane, and John Coglan. "Force-Velocity Relationship and Stretch-Shortening Cycle Function and Endurance Athletes" The Journal of Strength and Conditioning Research. 18.3: 473-479
8. "Plyometrics." Sports Coach. Brian Mackenzie, Editor
9. Paavolainen, Leena, Keijo Hakkinen, Ismo Hamalainen, Ari Nummela, and Heikki Rusko. "Explosive Strength Training Improves 5 km Running Time By Improving Running Economy and Muscle Power." Journal of Applied Physiology. 86 (1998) 1527-1533
10. Blakeyl, Jay b and Don Southard. "The Combined Effects of Weight Training and Plyometrics on Dynamic Leg Strength and Leg Power." The Journal of Strength and Conditioning Research. 1.1 (1987) 14-16
11. Turner, Amanda M., Matt Owings and James A. Schwane. "Improvement in Running Economy After 6 Weeks of Plyometric Training." The Journal of Strength and Conditioning Research. 17.1 (2003) 60-67
12. Johnson, Ronald E., Timothy J. Quinn, Robert Kertzer, and Neil B. Vroman. "Strength Training in Female Distance Runners: Impact on Running Economy." The Journal of Strength and Conditioning Research. 11.4 (1997) 224-229
13. Brown, Lee E. "Training for Speed, Agility and Quickness." American College of Sports Medicine. May 2003 Newsletter
14. Anderson, Owen. "Strength Training Routines: Is Strength Training Really Beneficial for Endurance Athletes." Peak Performance.







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