September 26, 2025, 11:24 am | Read time: 6 minutes
For the body to become stronger during strength training, muscles must be exposed to increasingly higher resistance to stimulate them. This is the only way they can grow. The best results are achieved by continuously overloading them, specifically with progressive overload. FITBOOK author Tony Poland, along with athletic trainer Dr. Timo Kirchenberger, explains what this entails and how to train correctly using this method.
What is Progressive Overload?
The principle of progressive overload means nothing more than continuously increasing the load on your body during regular training. This is the only way it can adapt and make progress in terms of results. “Progressive overload is one of the most fundamental principles of exercise science. When adhered to, it results in a corresponding training effect,” says Dr. Timo Kirchenberger.
Why New and Higher Training Stimuli Are Crucial
Through overload, we can build muscles, increase our strength, or improve our endurance. If the training stimulus remains the same, the body quickly adapts, leading to stagnation. “Without some form of systematic, structured overload or regular increase, there is no adaptation or only a very minimal one,” explains the fitness expert. “This means the body constantly needs new and higher stimuli to adapt. Only by coaxing the body out of its comfort zone can muscle growth be achieved.”
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“The Prerequisite Is Progressive Overload”
Regardless of our training goals, progressive overload is essential. It doesn’t matter if we focus on muscle building (hypertrophy) or if we want to increase our strength to lift heavier weights. Kirchenberger provides more examples: “I might want to improve my muscular endurance, get faster or have bigger muscles, or improve my maximum strength. The prerequisite for this is progressive overload.” Depending on the goal, one should tailor and prioritize their workout program accordingly.
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More Weight or More Repetitions?
We can introduce new and higher training stimuli in various ways. If we want to build muscle mass, multiple repetitions with moderate weights are ideal. This intensity challenges the muscles to stimulate growth. Very heavy weights with fewer repetitions are recommended if we want to increase our strength, as they challenge the nervous system and muscle fibers to boost maximum strength.
Of course, we can also opt for lighter weights but significantly increase the number of repetitions. In this case, we work on muscular endurance or maintaining muscle mass, improving the muscles’ ability to work over extended periods.
Structuring Training Cycles
It’s advisable to prioritize your program in specific training cycles. For example, you could focus on one area for twelve weeks and follow a 5×5 regime (5 sets of 5 repetitions). “After a week off or a recovery week, you could start a new cycle with 5×12 or 5×3. The task is to ensure progressive overload for the next twelve weeks,” advises the personal coach. The goal is always to progress from the starting point (with the number of repetitions) and introduce variety and new stimuli. This continually challenges the muscles, promoting strength gains and muscle growth.
Up to 5 Percent Weight Increase for the Lower Body
While the number of repetitions can be changed at will, increasing the weight is not as simple, especially when aiming for higher weights. “The question is, what is an adequate increase?” says Kirchenberger. “With a squat at 100 kilograms, I can imagine that 101 or 102 kilograms might be possible the following week. An increase of two to five percent from week to week is a good and adequate progression for lower body exercises,” recommends the former competitive athlete. “It’s ambitious but not unrealistic.” This can create a good and meaningful overload.
However, weight cannot be increased indefinitely–there’s a risk of injury. Proceed cautiously, train with a spotter during challenging free weight exercises, and seek advice and support from trainers.
Up to 3 Percent Weight Increase for the Upper Body
For upper body exercises, the increase is significantly smaller. Kirchenberger explains the reason using the example of shoulder presses. “Here, much less muscle is involved, so the increases can’t be as large.” The expert advises a weekly increase of about one to three percent for exercises like bench presses or generally for the upper body.
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Weight Too Heavy? Change Training Cycle
Every athlete eventually reaches a point where a higher weight is no longer possible. In this case, consider modifying your system. Instead of a 5×5 training cycle over about eight weeks, you could switch to 5×8 and adjust the number of sets accordingly. This ultimately ties back to the number of repetitions…
Other Methods to Increase the Stimulus
It’s not just about playing with weight or the number of repetitions. There are other methods, though less common in practice. “You can change the training by adjusting the tempo,” says the expert. “For example, keep the weight but work with a pause in the lowest position (hold the exercise at the turning point; editor’s note). There are also tools like chains or resistance bands that can introduce a small increase.” These more complex variations ultimately increase the intensity.
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Beginners Improve Quickly!
The principle of progressive overload is suitable for everyone, from beginners to seasoned pros. “It starts with rehab. If you’ve been injured and are doing muscle-building training to stabilize your knee after surgery, you must train progressively. You must regularly overload the knee, or you won’t achieve muscle growth,” emphasizes Kirchenberger. Beginners typically improve the fastest because their bodies adapt quickly when they stick to their training. Progress usually slows at the advanced level.
What the Research Says
The assumption that progressive overload leads to strength gains and muscle growth (increase in muscle cross-section) has been confirmed by research. For instance, a study from 2024 examined the effects of progressive overload in leg training among 39 untrained individuals (20 men, 19 women) over ten weeks. The study showed that both increasing the load through weights and increasing the number of repetitions can be used to promote strength gains and muscle hypertrophy.1