Speed-Strength Versus Strength-Endurance

Another way to define muscular strength is by the speed of contraction, or speed-strength. You can contract your muscles slowly, as you do when you complete a typical barbell bench press. Or you can contract them quickly and explosively, as you do for a vertical jump or Olympic power clean. The barbell bench press is an example of low-speed muscular strength whereas the explosive vertical jump or Olympic power clean shows high-speed muscular strength. Low-speed muscular strength involves lifting the heaviest weight possible for one repetition, as in power lifting or lifting a child from the ground into your arms. High-speed muscular strength involves a factor called power, which means exerting force very quickly (as you learned in chapter 4).

We see high-speed muscular strength in virtually all sports, and we also experience it in certain aspects of our lives. Examples from daily living include jumping up from a chair to answer the doorbell or rushing up a set of stairs when you are late. You can incorporate speed-strength into a pure strength-training program without doing Olympic lifts, simply by decreasing the weight you lift and increasing the speed at which you lift it. Choose one exercise in your routine for the day and concentrate on how fast you can move the weight (while still maintaining proper form) rather than how much weight you can move. Vary the exercises you choose throughout the weeks so that you can experience speed-strength with different movements.

If strength is the ability to exert force and endurance is the ability to maintain an activity, then strength-endurance is really the ultimate combination that everyone seeks to achieve. It would be awesome if we could maintain maximal muscular activation and contraction for extended periods, but is the combination even possible? Aren't the two abilities, by their very definitions, at odds with each other? Is strength-endurance even a relevant concept for the average person to consider?

Muscular strength and muscular endurance do seem to be the opposite of one another. They tend to differ in which muscle fibers they incorporate, in the way those muscles work, and in the way that they use energy from the body. Their goals are also totally different. Demonstrating strength requires you to complete a short, intense event, whereas showing endurance requires you to finish a long, moderate- to low-intensity event. Logically it might seem that your body couldn't do both. But what happens when the two abilities have to combine for a special occasion? Are they able to work in unison or does one win out over the other?

Strength and endurance come in closest contact with each other during sports movements. Some sporting events require both great strength and exceptional endurance at the same time. Think about the decathlon, mountain climbing, rowing, and adventure racing. What they all have in common is the need to recruit large numbers of muscle fibers to move the body powerfully for long distances. We know that typical gains in muscular strength occur with lower numbers of repetitions, and gains in muscular endurance occur with higher numbers of repetitions. Higher repetition ranges also take longer to complete than the lower ranges. Strength-endurance training uses the principle known as "going to failure" on exercises. Going to failure means you lift as heavy a weight as you can for as many repetitions as you can, until you can't lift it anymore (usually somewhere in the range of 75 to 85 percent of 1RM for 8 to 12 repetitions). For strength-endurance exercises you take your time with sets, going slowly so that the whole set takes up to 1 minute to complete. The reasoning is that what we call time under tension produces both strength and endurance gains in muscles.

The physical demands of athletic events don't often closely simulate the demands of our daily lives, even if we are construction workers or engage in physically demanding professions. Our usual routine consists of periods of rest (some shorter than others) interspersed with low, medium, and high levels of activity. Although each day paints a different picture, in general we lead pretty routine lives. With the exception of weekends, special occasions, and vacations, we are creatures of habit. Even if we do have a physically demanding job, we don't go all out every minute of the day; we take intermittent breaks for a bathroom visit, lunch, or chat.

We need strength-endurance in our daily lives when we perform tasks such as carrying in groceries on a big shopping day. Let's say that one bag weighs 25 pounds. No matter who you are or how strong you are, that bag is still going to weigh 25 pounds. If your 1RM in the dead lift is 100 pounds, then that 25-pound bag represents 25 percent of your 1RM. Since it weighs only 25 percent of the total amount of weight you could lift one time, the bag would be light for you and you wouldn't have to exert much effort. The greater your strength and the higher your 1RM, the lighter the 25-pound bag is going to be for you. If it seems like a light weight to you, you will be able to lift it many more times before becoming fatigued-- carrying in 12 bags of groceries won't be a major undertaking in your day.

You can argue that strength-endurance is exactly what we use in our daily activities. Nevertheless, your strength-- how much weight you can lift one time-- is actually the basic issue. In the preceding example, carrying in the groceries came on the heels of walking around the grocery store, standing in the checkout line, and sitting in the car on the way home-- activities that don't require exceptional strength or endurance. Taking the groceries into the house probably doesn't take long, but if the groceries seem light to you, you can do it even faster. You can also unpack and store everything more quickly and easily so that you have time for a short break before starting to make dinner. The point is that our bodies are used to our daily routines and therefore do not typically need additional endurance for us to last longer doing these things; we can usually push ourselves to do whatever needs to be done. However, we do need additional strength to make everything that we do in a day feel easier. Increasing our strength, then, is the best way not to feel worn out at the end of the day. Because the activities in our lives largely involve whole-body movements, we should include multi joint exercises that use many muscles so that our strength-training sessions closely simulate how we use our bodies every day.