“Exertion” in weight training is defined as the effort level during a set of an exercise.

A maximum rate of exertion would be training to failure, where an individual would complete as many reps as possible with maximum effort.

The natural instincts of beginner lifters tend to lead to a mindset where a set is only valuable if you have reached failure and pushed your limits. It comes back to the “more is better” mindset. However, maximal exertion is not the best method to progress in strength or tension overload. Training to failure may have acute benefits, but only when implemented strategically and appropriately in a training program. This is backed in a study by Folland, who claimed: “fatigue and metabolite accumulation do not appear to be critical stimuli for strength gain, and resistance training can be effective without the severe discomfort and acute physical effort associated with fatiguing contractions” [22].

Why You Should Avoid Training To Failure

Consistent reaching of muscular failure is counterintuitive for long-term progress, due to its effect on the nervous fatigue and recovery abilities.

Dr. Mikel Izquierdo found that training to failure every set vastly increased resting levels of the catabolic hormone cortisol and suppressed anabolic growth factors such as IGF-1 [19]. Researchers have also found that maximal exertion in resistance exercises ramped up levels of the nucleotide adenosine monophosphate (AMP) dramatically compared to non-failure training. An elevation in AMP is a sign that the cell is drained of energy, and when this occurs, protein synthesis decreases [20].

Be confident in the evidence that progress can be made and even maximised, when you leave some potential energy in the tank. In other words, if you know you can complete 10 repetitions with maximal effort, aim to complete 8-9 repetitions. This can be a hard concept to grasp for many weight lifters. A practical, real world example may help confirm this point –

A practical, real-world example may help confirm this point –

Set 1 – 10 repetitions (max effort) Set 1 – 8 repetitions Set 2 – 8 repetitions (max effort) Set 2 – 8 repetitions Set 3 – 7 repetitions (max effort) Set 3 – 8 repetitions Set 4 – 5 repetitions (max effort) Set 4 – 8 repetitions TOTAL – 30 repetitions TOTAL – 32 repetitions

The example represents a common case where individuals detrimentally affect the main workout focus (total work volume) by pushing themselves too hard.

Not only does maximal exertion affect recovery abilities from workout to workout, but it affects acute recovery from set to set. This is seen in the example where repetitions inevitably decrease each set due to the inability to maintain maximal performance over any significant period.

Maximal exertion develops “central fatigue”, thereby all following sets will be performed at a much lower capacity. As you can see, working at 80% of maximal exertion (8 repetitions) allowed maintenance of this performance, resulting in an overall increase in total work volume (32 vs 30 repetitions). This leads to greater progressive tension overload in the muscles worked.

It’s Not All Bad

Despite this, maximal exertion and training to failure does have acute benefits. I like to stick to a <10% rule for when this style of training should be implemented for a set.

Brad Schoenfeld discovered that training to failure causes greater increases in lactic acid in the muscle, which can create increases in intramuscular growth factors and initiate hypertrophic responses [21].

In resemblance to short rest periods as discussed in the “Rest Periods” section, training to failure can also induce metabolic fatigue and effectively act upon a muscles upper threshold fibers. If one wishes to perform a set to failure, it should be the last set, as it will therefore not affect performance in proceeding sets.

Summary – Stay 1-2 repetitions away from maximal exertion.


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References

19) Izquierdo M, Ibañez J, González-Badillo JJ, Hakkinen K, Ratamess NA, Kraemer WJ, French DN, Eslava J, Altadill A, Asiain X, Gorostiaga EM. 2006. Differential effects of strength training leading to failure versus not to failure on hormonal responses, strength, and muscle power gains. J Appl Physiol. 100(5): 1647-56.
20) Gorostiaga EM, Navarro-Amezqueta I, Calbet JA, Hellsten Y, Cusso R, Guerrero M, Granados C, Gonzalez-Izal M, Ibanez J, & Izquierdo M. 2012. Energy metabolism during repeated sets of leg press exercise leading to failure or not. PloS One. 7(7): e40621.
21) Schoenfeld BJ. 2013. Potential mechanisms for a role of metabolic stress in hypertrophic adaptations to resistance training. Sports Med. 43(3):179-94.
22) Folland JP, Irish CS, Roberts JC, Tarr JE, Jones DA. 2002. Fatigue is not a necessary stimulus for strength gains during resistance training. British Journal of Sports Medicine. 36:370-373.