You’re probably wondering how strength training improves endurance performance. Strength and endurance training seem like they are on opposite ends of the workout spectrum, so how can one help the other? Well, the answer isn’t simple, but it is pretty logical, and it boils down to the concept of speed of muscular contraction (or, more technically, power).
The goal of all endurance athletes is to be faster: to run faster, to swim faster, to bike faster, to get across the finish line faster. In order to do this, muscles must repeatedly contract to propel the athlete along the course, all while resisting fatigue. Strength training, when performed properly (correct exercises, sets, reps, rest intervals, and poundage), dramatically increases the amount of force that all muscle fibers can produce (even the so-called Type I endurance fibers). Stronger muscles mean greater force production. Greater force production means greater propulsion of the body during the drive phase of the endurance activity. Examples of the drive phase of endurance activities would be the “push-off” phase of running, the down stroke during pedaling a bike, or the kicking and pulling action during swimming. So, simply speaking, by increasing force production during the drive phase, resistance training makes endurance athletes faster.
Power & Rate of Force Development
Furthermore, if strength training movements are performed at an increased speed of movement, power production and rate of force development increases. Power is the product of force and velocity, and it is essentially the key muscular attribute to all athletic success, with endurance sports being no exception. As an endurance athlete, you need force to overcome your own body weight, but you also need fast and rapid muscular contractions to go fast. Proper, power-based strength training results in greater amounts of force being generated in shorter periods of time. In running terms, this reduces ground contact time, and increases force produced in that split second the foot is in contact with the ground, which makes you faster. When cycling or swimming, this type of training allows more force to be applied over a shorter period of time to increase speed. So, contrary to the popular misconception that speed can’t be trained, it can be — you just have to do the right type of training.
Lastly, strength training improves the ability of connective tissue to store and release elastic energy. Essentially, your connective tissues (tendon and ligaments) are like springs — they compress with ground contact during running, storing energy, and that energy is in turn released when the connective tissue springs back to (and beyond) its resting length during the drive phase of the running stride. Since this is merely the transfer of elastic energy, it has no associated metabolic costs (meaning it allows you to produce more force without costing you more oxygen or energy).
The three mechanisms discussed above (force, power and rate of force development, and improved elasticity) all allow endurance exercise to be performed more economically. More economical endurance athletes perform at the same speed with lower energy costs than their less economical counterparts (and therefore go for a longer duration). More economical endurance athletes can also perform at a greater speed for the same energy costs (and therefore go faster). Either way, the more economical endurance athlete has a dramatic performance advantage.
To improve your endurance performance through strength training, try to integrate two (non-consecutive) days of resistance training per week, performing large structural lifts such as squats and deadlifts, along with supplemental exercises for the core, hamstrings, and shin musculature to prevent injury. Sets should be performed with either heavy weights (>90% of max), low reps (<4), and long rest intervals (> 3min) to increase strength without increasing muscle size (which would slow you down), or lighter weights (30-60% of max) moved at a high velocity for a low number of reps (<6), and long rest intervals (> 3min) to increase power and rate of force development.
If you’re new to strength training and don’t quite feel comfortable with the lifts or loads mentioned above, we can help!