Strength training in the endurance sport world can be rather taboo. Especially when elite level marathoners include little strength training in their programmes and nearly half do no strength training at all ([1] as cited in [2]).

But strength and power training is an all too important component in improving the efficiency of running. Otherwise known as running economy. Running economy (RE) can be defined as the steady-state V02 required at a given submaximal speed [2]. It is likely that any improvement in RE will be associated with improved long-term endurance performance [3]. RE is accounted for by factors such as anthropometry and age but is also largely influenced by training strategies. Most notably, strength and power training. Strength training contributes to enhance endurance performance by improving the economy of movement, delaying fatigue, improving anaerobic capacity and enhancing maximal speed [3].

Factors effecting running economy [4]

Increased maximal strength reduces the amount of activated muscles mass needed to generate the same absolute submaximal power [3]. Put into a running context, this allows a runner to do less work at a given running speed [4]. Effectively, making you a more efficient runner. Furthermore, plyometric training has the potential to increase tendon stiffness, allowing the body to utilise elastic energy more efficiently, resulting in decreased ground contact times and reduced energy expenditure [5].

Why is running economy so important?

Running economy is a measure of how much (or little, as the case may be) oxygen the runner uses for a given, sub-maximal speed. In theory, two runners can have the same maximal capacity for oxygen use (called VO2max), and the one who is more economical at the sub-maximal speeds is likely to be the better runner. I.e. less effort is required for a given sub maximal pace. Performance in most endurance events is mainly determined by the maximal sustained power production and the energy cost of maintaining a given competition speed [3].

A recent meta-analysis by Balsalobre-Fernandez et al., [2] looked at the effects of strength training on running economy in highly trained runners. The studies included in this meta-analysis had to meet the criteria of being middle or long distance runners, VO2 max greater than 60mL.kg.min (well trained endurance runner) and be controlled trials using strength training greater than 4 weeks and measuring RE before and after the strength training intervention. From the 174 unique results, only 5 studies met the inclusion criteria which combined resulted in an overall sample size of 93 well trained runners.

Strength training interventions ranged from 8-12 weeks long with 2-4 sessions a week where training lasted 15-90mins. Volumes ranged from 1-3sets of 4-10 reps at low to moderate/high intensities (40-85% 1RM) with 1-4 exercises in conjunction with 2-6 unloaded plyometric exercises.

What Did The Authors Find?

Strength training had an overall, significant, large beneficial effect on running economy (-2.32 ± 2.07ml.kg.min change in RE) while the control group showed a 0.57 ± 2.48ml/kg/min change in RE. From this meta-analysis, it is suggested that strength training be performed approx. 30% of total training sessions i.e. 6:2-9:3 endurance:strength training session ratio.

A brand new study by Beattie et al., [6] supports the above reviews findings with one of the longest strength training interventions to date within the published literature. They looked at the effects of 40 weeks of strength training on performance indicators in distance runners. The authors found significant improvements in relative strength (1RM back squat), fast reactive strength (drop jump), running economy, velocity at VO2max without significant changes in body composition (i.e. muscle size).

Practical Applications

According the above research, strength training should be performed with multiple leg exercises [3]. Furthermore, resistance training should closely simulate the competition movement so explosive training should also be performed. Studies that showed no improvements in endurance performance generally were short term with a low volume of strength training or only using explosive strength training [3]. From the research presented above, 2-3 strength/power sessions should be performed along-side your endurance training. Intensities should remain moderate to high (i.e. medium to heavy loading), while volume should be kept low to moderate ranging from 1-3 sets and 4-10 reps. Unloaded plyometric exercises should also be performed with volumes up to 200 jumps per week (training history and current ability dependent).

Summing Up

While the highest VO2max does not necessarily equate to the best endurance performance, the best endurance performance typically requires high VO2max values [3]. Similar to strength training where performance at sub maximal loads requires typically high maximal strength, a high RE also requires a typically high VO2max. However, once a high VO2max is reached, becoming more efficient at sub maximal paces becomes a greater determinant to endurance performance. RE can be improved with simultaneous resistance and endurance training without affecting running performance.  Incorporating strength training to your weekly training schedule will not only improve your running economy, but also aid in preventing injuries and restoring any postural issues.