What is failure?Muscular failure during training represents the point when the neuromuscular system is unable to generate further increases in force to overcome a particular workload, set, or series of sets. Therefore, the individual has to stop or discontinue the set. This is followed by a brief recovery session where ATP is resynthesized. During this recovery time, some metabolic byproducts (i.e. hydrogen ions, lactate, creatine) inside and outside of the muscle fibers are removed or restored. Now, this is very important and probably a foundational basis of error. At this point, the muscle fibers involved are not completely fatigued. Simply, they just can’t generate enough force to overcome the particular load. This is why the overall load usually has to be decreased to a lighter load.
The theoretical basis of training to failure is based on, of course, motor unit recruitment and muscle fiber types. It is motor unit recruitment (and muscle fibers) that is the foundation of the force production needs of the muscle. To further illustrate this, see Table 1. In addition, if strength is the primary goal (which it almost always is), the magnitude of activation of motor units is directly linked to the magnitude of the strength training response.
Table 1: Fiber type characteristics
An early study by Rooney, Herbert, and Balnave (5) investigated the effects of training to fatigue by examining strength increases produced by a training protocol in which subjects rested between contractions versus those individuals who didn’t rest between repetitions. Forty-two male subjects were randomly assigned to a ‘no rest’ group, a rest group, or a control group (who did no training). Subjects in the two training groups trained their elbow flexor muscles (biceps) with a 6RM load for 6–10 reps three days per week for six weeks. Participants in the ‘no rest’ group performed repeated lifts without resting whereas subjects in the rest group rested for 30 seconds between each repetition. Intensity and volume of training were equated. The study showed that subjects who trained without rest experienced significantly greater mean increases in dynamic strength (+56.3 percent) than subjects who trained with rest (+41.2 percent).
While failure can be a valuable tool in a bodybuilder’s training routine, there is some evidence to indicate that it comes with a significant cost. Izquierdo (4) found that training to failure every set significantly increased resting levels of the catabolic hormone cortisol and suppressed anabolic growth factors such as IGF-1. This investigation demonstrated a potential beneficial stimulus of non-failure for improving strength and power whereas performing sets to failure resulted in greater gains in local muscular endurance. This study may indicate that bodybuilders who take every set to absolute failure may put themselves at risk of impeding long-term growth.
From a metabolism perspective, Gorostiaga (3) found that training to failure significantly increased levels of the nucleotide adenosine monophosphate (AMP) versus non-failure. Simply, elevated levels of AMP are an indicator that the cell is depleted of energy. As a result, protein synthesis is reduced. Athletes need to be aware that this particular training approach can be taxing and should be used intelligently.
In contrast to the previous study by Rooney (5), Drinkwater and colleagues (2) examined 26 elite junior male basketball players and soccer players, all who had been doing resistance exercise for the previous six months. The subjects completed bench press training three times per week for six weeks using equal volume programs (24 repetitions at 80–105 percent 6RM). Subjects were assigned to experimental groups designed either to elicit repetition failure with four sets of six repetitions (failure) or complete eight sets of three repetitions not to failure (non-failure). The training to failure group demonstrated significant increases in strength (+9.5 percent) and power (+10.6 percent) over the non-failure group in strength (+5.0 percent) and power (+6.8 percent).
Although the results from these two studies are mixed, they provide insight into the fact that physiological and metabolic processes are linked with fatigue and contribute to the strength training response.