How Hard Do You Need to Train in the Gym?

In high school, I believed that harder was better. I crushed every workout, but underperformed in competition. As punishment for my poor performances, I would make up for it with another hard workout.

In grade 12, I learned about overtraining. I had experienced nearly all of the symptoms.

Symptoms of Overtraining (or more often, Overreaching)

Stagnant or declining performance

Lingering soreness

Higher perceived effort

Elevated resting heart rate

Chronic fatigue

Frequent illness

Poor sleep

Mood swings and irritability

Loss of motivation

In my final year of cross-country, I decided not to race each workout and raced consistently well. I then went back to my old ways, only to stagnate. I didn’t have another breakthrough until I was 24, again by training smarter.

In the last few years, several studies have compared training to failure with going easier on strength and muscle-building.

Note: The term “reps in reserve (RIR)” means how many reps you’re still able to perform after finishing a set. Training to failure means you have 0 RIR, while finishing your set with the ability to perform 3 more reps means you have 3 RIR.

A 2023 study by Ruple and colleagues compared lifting to near failure (0-1 RIR) to training moderately hard (4-6 RIR). 

They found little difference between groups in strength development. Training near failure, however, was more effective for muscle building.

This means that if you could have done 10 reps, doing only 4-6 reps is just as effective for strength development. You’ll feel a lot better after, too.

Four to six repetitions in reserve versus near failure is a wide gap. A 2025 study by Hermann and colleagues narrowed things down for us. They compared training to failure versus 2 RIR.

Training to failure was slightly better for muscle building, and there was no difference for strength or muscular endurance.

Why Might We See These Results?

The authors of these studies noted that coordination between muscles and within a muscle is important for strength development. Fatigue and soreness negatively affect the development of this coordination. Therefore, we don’t want to constantly train to the point of failure.

Muscle-building is a little different. Muscle fatigue and soreness can be beneficial, although not always necessary. 

How Can We Apply These Studies?

To maximize long-term progress, you need to train hard, but not so hard that it negatively affects your next workout.

For multi-joint exercises such as squats, deadlifts, and presses, you should leave two or more reps in reserve to build strength. This ensures better technique and a lower risk of injury. This is where starting your first sets lighter and building up to one or two top sets is beneficial.

Occasionally, push yourself to see how many reps you can complete at a given weight. If you’re newer to resistance training, you might not be good at estimating how many reps you have in reserve. 

When your progress stalls, take a deload. In a deload, you back off the volume or intensity for each exercise. Fatigue and fitness are in a constant battle. With a deload, you maintain fitness while reducing fatigue, supporting future improvements in performance.

For higher rep isolation exercises, you should train closer to failure. When introducing a new exercise, start with a few reps in reserve to prevent excessive soreness. In subsequent weeks, push one or two sets to near failure and test yourself occasionally.

In conclusion, your goal should be to train moderately to hard while ensuring proper technique, occasionally pushing yourself. 

Stimulate, Don’t Annihilate!

References:

Hermann, T., et al. Without Fail: Muscular Adaptations in Single-Set Resistance Training Performed to Failure or with Repetitions-in-Reserve. Medicine and Science in Sport and Exercise, 2025.

Ruple, B., et al. The effects of resistance training to near failure on strength, hypertrophy, and motor unit adaptations in previously trained adults. Physiological Reports, 2023.