Train it or Lose it - Strength = Power, Part 1
In athletic terms, “power” is a much lauded quality for human beings to possess. The MLB pitcher who can throw a fastball in excess of 100mph, the tennis player with an almost un-returnable serve, the boxer with a knockout loaded in almost every punch; these are all obvious displays of explosive power. With such extreme examples of this capability in the limelight, we are quick to overlook the demand for this skill in our daily lives, but make no mistake, this physical attribute is as essential to our quality of life as it is to the professional athlete’s paycheck. Ascending a steep staircase, climbing over an obstacle, and even just pushing a tired body back up from a nice rest in a comfy chair are all activities requiring the use of athletic power. In modern society, not only do most of us give scant consideration to this aspect of our fundamentally physical existence. But we take it as a truism that whatever such power we might possess in our youth, it will certainly deteriorate considerably as we age. We must resist this apathetic descent into sedentary darkness and reclaim our freedom to move with purpose!
Fortunately, recent advances in the study of exercise science have given us a better understanding of where “power" comes from, and most importantly, how not to lose it. The rate at which force is generated provides us a simple definition of power in this context and as such, we are simply talking about a combination of strength and speed. There has long been a debate as to whether or not our muscle contractions get slower as we age, or if they just get weaker, causing a decrease in the ability to produce explosive power. This decline is obvious as it pertains to athletic performance but eventually it has a big influence on our ability to carry out the activities that enable independent living; a turning point when it becomes much more difficult to reverse. A team at Manchester Metropolitan University published a study just last year (https://journals.plos.org/plosone/article/authors?id=10.1371/journal.pone.0253531) that provides some important insights to settle this debate between speed and strength. First, each subject’s leg strength was assessed relative to their bodyweight, and their jump height was used as a determination of power output. As one might expect, the younger participants were generally stronger and able to jump higher. But by weighing down the younger participants and providing pulley assistance to the older ones, they were able to equalize their relative strengths. With the playing field leveled in this manner, the team observed that there was no significant difference in the speed of muscle contractions between the two groups when they performed a vertical jump. So it turns out that, as my fellow strength enthusiasts would likely have hypothesized, our muscles probably don’t somehow contract more slowly as we age, they just get weaker and thereby less able to produce power. The research team also compared their data with results of a “Timed Up and Go (TUG) Test,” which is a reliable assessment for quantifying functional mobility. For this test, subjects are asked to rise from a standard armchair, walk to a marker three meters away, turn, walk back, and sit down again. The study concluded that the critical power output level required to perform the basics of independent living (as simulated by the TUG) is about 23.7 watts per kilogram of bodyweight. If we fall below this threshold ability, just getting up out of a chair and moving around becomes too much of a challenge. Maintaining strength means that we also maintain power, and that includes the power to function independently. How can this not be something eagerly prescribed by doctors along with the usual host of pharmaceutical interventions that seem to multiply as we age?! Now that it has become even more obvious that athletic power is a quality we all must work to preserve and that strength is the key, how do we ensure that our training addresses this concern as directly and safely as possible? When most coaches think of “power” exercises, box jumps and explosive push ups spring to mind and frighten away even the most enthusiastic trainees. Too often a history of injury or just a more sedentary lifestyle imposes too great a restriction on a trainee’s safe range of motion for them to readily consider explosive movements as part of a training regimen. But the solution is not to give up and avoid them entirely! The problem in most cases is that coaches are only focused on the ability to expel energy and comparatively little practice time is spent on the skill of absorbing it. But if we take multi-joint, compound movements and directly focus on training mastery of their component parts, we can unlock the skills of power generation more effectively and safely.
Thanks to the work of coaches like Calvin Dietz, strength coach at the University of Minnesota and for the USA Olympic Hockey teams, we know that improved force production isn’t all about training the concentric phase of a movement. To safely work on explosive strength, we must spend as much practice time in the eccentric and isometric phases of dynamic movements as we do with the concentric phase. This means that we train the loading or yielding phase (eccentric) of a lift and the pause that occurs as the energy is transferred (isometric phase) with as much enthusiasm as the muscle contracting, dynamic power output phase (concentric). For example, if we can become confidently skilled and strong in the descending movement of a squat, and fully own the pause at the bottom, then the return to standing (even at high speeds or under loads) will become a stronger, safer affair. Lest you think this only applies to movements in the gym, the same goes for getting up from a chair, obviously. The crux of all this is to say that a body capable of absorbing more energy will also be capable of expelling more energy. Most of us aren’t hesitant about performing a high jump because we’re worried about the jump, we’re worried about the ability to safely absorb the shock of the landing. As such, the ability to safely land from greater heights will help us unlock the ability to jump to greater ones! Whether we want to be able to generate more power for sport, enjoy an active outdoor lifestyle or simply continue living independently, we mustn’t neglect training for explosive power. And to possess power, we must first possess strength. It is my hope that I’ve been able to pique your interest in this concept of effectively training the three phases of a dynamic movement for greater strength and power.
Stay tuned for more detail on this topic in my next Coach’s Corner; Strength = Power Part 2!