Programming for strength and muscle growth is often done at the extremes – lifting as heavy as possible and pushing sets close to failure. But emerging research suggests the most effective approach requires a little less bravado. A new study exploring how load and fatigue interact in resistance training offers a clearer picture of what’s actually required to build strength.
The Study
A new study published in Medicine & Science in Sports & Exercise offers one of the most detailed looks yet at how training intensity and proximity to failure interact to drive strength and muscle growth. The takeaway is more nuanced than simply ‘lift heavy’ or ‘train to failure’.
Researchers analysed how different loads and fatigue levels affect adaptations to resistance training, using the bench press as a controlled model. By manipulating both intensity and effort, the study aimed to isolate what really matters for building strength versus size.
The Methods
The study included 158 strength-trained men, split into 12 groups. Each group trained using different combinations of load (around 48%, 63% or 78% of 1RM), while proximity to failure was measured via velocity loss.
Velocity loss is a method of tracking fatigue within a set: as rep speed decreases, fatigue increases. A higher velocity loss indicates training closer to failure.
Participants followed an eight-week, bench press–focused programme. Pre- and post-testing assessed maximal strength, reps to failure and muscle size.
The Results
Strength
For strength and power, heavier loads consistently came out on top. Training in higher intensity ranges (roughly 70-85% of 1RM) produced the greatest improvements in maximal strength – particularly when sets were stopped at a moderate level of fatigue (around 25-30% velocity loss).
As researcher and coach Menno Henselmans explains: ‘To maximise strength, your training should have high muscle activity and high force outputs. Too much fatigue, which you typically get from training very close to failure, can be detrimental.’
Hypertrophy
Muscle growth followed a different pattern. The closer participants trained to failure, the greater the increases in muscle size. Higher velocity loss thresholds – indicating more fatigue within a set – were associated with greater hypertrophy.
This aligns with a broader body of research showing that training volume is a primary driver of muscle growth. As Henselmans notes: ‘The higher repetition volumes from training harder increase muscle growth,’ reinforcing the idea that effort – not load alone – is key.
What Does This Mean for You?
Despite some variability in the data, the overall trends are clear. Strength is driven largely by neural adaptations in the short term, benefiting from heavier loads and controlled fatigue. Muscle growth, on the other hand, responds well to higher overall training stress – often achieved by working closer to failure.
If your goal is to build strength, it pays to hold back slightly. Training to failure on every set creates excessive fatigue, which can limit performance and reduce the quality of subsequent reps. Stopping short of failure allows you to maintain higher force output across sets – one of the key drivers of strength gains.
If your goal is to increase muscle size, pushing closer to failure may give you an edge.
That said, you don’t need to hit failure to build muscle. Research consistently shows similar gains in strength and size when training close to failure. In practice, stopping a few reps short – around 3-5 reps in reserve – strikes an effective balance between maximising stimulus and managing fatigue.
The Bottom Line
Strength and muscle size are closely linked, and evidence shows you can build both across a wide range of rep ranges – provided effort and total training volume are sufficient.
