Strength is the physical capability of force production. Technically it is the ability to produce maximal force, but in layman’s terms it is being able to pick up heavy things.
There are essentially two components of strength: the muscular and the neural. Or, to put it another way, the hardware and the software. The hardware is the actual fibers of your muscles themselves. The muscle receives an electrical signal and contracts, thus producing force. All other things being equal, a larger muscle will produce more force. Of course, people often forget about the all other things being equal part, and assume that the only way to get stronger is to get bigger. They’re forgetting about the neural component to strength.
Your nervous system plays a huge part in how much force you can produce. It effects how efficiently your muscles fire, and how strongly they fire. That’s why smaller athletes can sometimes outlift bigger athletes, and why athletes in weight-category sports such as weightlifting and powerlifting can keep improving without putting on more mass.
Although when most people think of strength, they think of how much weight a person can lift in the gym, strength is a physical capacity that is useful across a whole range of tasks in real life. Getting stronger makes it easier for a new mum to carry her baby around; it helps when you’re moving into a new house; and it means that you don’t strain your back picking up a box at work. In fact, the best possible intervention for injury prevention isn’t putting up ‘Lift with your knees’ posters, or stretching regularly, or doing Yoga; it’s getting people stronger. A lack of strength is what puts older people into retirement homes. Once they can’t pick up their groceries up off the ground, or lower themselves onto the toilet, they lose their ability to live independently. On a related subject, being strong is one of the best things to do for longevity. Strength training prevents osteoporosis, meaning you don’t break a hip as easily. Also, have you ever seen an old lady walking down the street with her head pointed at her feet and her shoulders slumped forward? It isn’t because she didn’t do enough cardio in her youth, it’s because she’s too weak to assume a proper posture.
So strength is something people should do for healthy lives, but it is also something a lot of athletes would benefit from doing more of.
There are only a few sports where being strong is the actual competition. Powerlifting is one of the few examples of this. A powerlifter lifts his heaviest weight for a single rep on the squat, deadlift, and bench press. Whoever lifts the most weight wins. But most sports aren’t like that. The strongest soccer player doesn’t always help win the game, the strongest boxer doesn’t always win the fight and the long-jumper with the biggest squat doesn’t automatically win the Olympic gold medal. But a soccer player who gets stronger improves his acceleration, and thus can get to the ball faster. A stronger boxer can hit harder, and knock his opponent out. A long-jumper who is already powerful will be able to jump further if he gets stronger.
Movements such as jumping, throwing, or accelerating are dependent on power. Power is defined as force divided by time (i.e. producing force quickly). So we can improve power by making the top part of the equation bigger.
This is also true for another physical capacity: muscular endurance. As an example, doing a heavy set of 3 reps on the bench press is an expression of strength, while doing a set of 50 push-ups is an expression of muscular endurance. If you’re very weak, doing a lot of push-ups is hard because every rep is a large percentage of your maximum force. By increasing your force production, reps become easier, and you can do more. As a hypothetical, take two lifters. Lifter A can squat 150kg. Lifter B can squat 200kg. Who do you think can squat 130kg for more reps? For Lifter A that’s 86% of his maximum, but for Lifter B it’s only 65% – practically a warm up.
Strength training is very different from bodybuilding. Bodybuilders are concerned with getting the biggest muscles. They’re focused increasing size, not strength. Because of the different goals, the two types of training look very different. They have a saying in the NFL: ‘looks like Tarzan, plays like Jane.’ Does that sound like someone you know?