Going to Failure on Sets
There are two typical extremes when people come to the end of their sets. In one camp is people who stay very conservative in their sets, never pushing the chance of failure. In some cases these people are beginners who have not learned the ability of their body or how to push through pain yet. Others follow research out there that muscle damage and soreness should be avoided at all costs to keep the body continually at 100%. The other camp is usually meatheads and bros that push every set to failure, and then even have their spotters help them grind through 2 more reps. Obviously there is a middle ground that is optimal between these two camps, but where is it?
To find the answer I sought out an article from MASS written by Greg Nuckols. He reviewed multiple research studies on the topic, notably one study comparing sets to failure against sets to volitional interruption, or stopping the set one rep before failure. The study concluded that it was the total successful workload of the set that achieved the greatest muscle adaptation. Doing an extra rep that failed did not produce any significant difference in muscle growth. Also decreasing the load still achieved significant muscle growth only when still going to volitional interruption.
The takeaway is that the most successful set is where you can push yourself to the brink of failure without actually failing. Holding back too much will limit the total load of the workout, and decrease muscle adaptation, and failing reps will not grant any more gains, but decrease the amount of work you can do on successive sets.