Interestingly enough, pilots are acutely aware of their TWR, figure it regularly and must stay within certain guidelines to stay airborne. In contrast, fitness enthusiasts almost completely ignore the efficiency issue, and almost never get any regular percentage of body fat feedback, even though change in percentage of body fat (efficiency) is the best indicator of fitness improvement. The strength-to-weight ratio But, what happens if exercise physiologists change their approach, and measure efficiency as an aeronautical engineer does? In human physical efficiency, the concept comparable to TWR is called the strength-to-weight ratio (SWR).1 It compares muscle (not fat) to a person's overall body weight. And muscle, unlike fat, is active and easy to measure, since significant changes in muscle mass are reflected by significant changes in strength. And, so long as you perform some type of regular resistance training, the SWR approach has some important advantages over the percentage of body fat approach, including getting accurate and immediate feedback without special equipment, technicians, added time or added money. Also, clients can easily do it themselves. Feedback from the SWR is also more functional and user-friendly than the feedback from percentage of body fat. For example, SWR gives you specific feedback on the relationship between antagonistic and protagonistic muscles, and imbalances that may be present and may encourage injury. It can also give you the relationship between the upper and lower body, core muscle strength and proportionality that can affect performance. None of this information comes with a percent body fat reading, yet many exercise physiologists ignore SWR. The problem is that, even though the SWR concept has been around for more than a decade, exercise physiologists continue to use body fat measurements to determine fitness.

The SWR concept, which is technically an indicator of relative strength, may have never been tested for its ability to measure and document changes in human physical efficiency, even though engineers effectively use the corresponding concept every day. And, if nobody takes the time to test it, then the field of exercise physiology may be worse off because of it.

But, if you'd like to use the SWR, think about what you might do for your members and clients, who can get regular feedback on changes to their physical efficiency.

Calculating SWR