Relative Strength is muscular strength relative to body weight. Literally, relative strength is a person’s strength per kilogram or pound of body weight.
Since absolute strength is the total strength, as defined by the total force that can be exerted regardless of body weight, relative strength is found by dividing the absolute strength by body weight.
So RELATIVE STRENGTH = ABSOLUTE STRENGTH/BODY WEIGHT meaning that it measures the total strength per unit of body mass.
Thus, if an athlete’s one rep maximum for the back squat is 136 kilograms at a body weight of 113 kilograms, that athletes relative strength equals 1.2 for the back squat.
If the athlete gains 5 kilograms without improving his 1RM for the back squat his relative strength goes down to 1.1 and his absolute strength has not improved. However, if the increases his back squat by 5 kilograms while gaining 15 kilograms, his relative strength has decreased while his absolute strength increased.
Relative strength has a very strong correlation with performance in most athletic endeavors and for strength related competitions it is a lifter’s relative strength, rather than his absolute strength, that determines performance since these lifters compete within a specified weight class.
The large majority of the strength athlete population, then, is concerned with relative strength instead of absolute strength. Only for the highest body weight class does this distinction become less important.
This is also expressed as a power-to-weight ratio. It is also important in sports like wrestling, mixed martial arts, and gymnastics, where it is crucial.
Relative strength measurements are more useful when comparing one athlete to another, but a lifter should be concerned if his relative strength is going down, as this is an indication that body weight is being gained that does not correlate with absolute strength, meaning that the weight gain is probably fat instead of muscle.
In sports where the athlete controls his or her body weight, such as gymnastics, wrestling, figure skating, rock climbing, boxing, running, etc., relative strength is of the utmost importance as any excess body weight will be a detriment to performance and these athletes must develop as much strength as possible per each unit of body mass.
A female’s absolute strength is, on average, less than that of males. Their upper body strength averages around 55% of a male’s and lower body strength around 70%. Interestingly, however, these differences are less pronounced for relative strength measures, especially for lower body strength, where it can be equivalent to that of males.
Pure strength training, or training for maximum strength, which is what I am primarily concerned with here on StrengthMinded, concerns absolute strength. Although excess body weight can be a detriment for some strength training lifts, the goal is this type of strength training is always to increase absolute strength.