Repetition ranges form a fundamental component of effective resistance training. The question of whether 25 repetitions is “too much” for a single set does not have a simple answer. The appropriateness of a 25-rep set depends entirely on the specific physiological outcome you are trying to achieve and how the set is executed. For most goals, this repetition count is not excessive, but rather a specialized tool. Understanding the purpose and mechanisms behind such high volume work is necessary to use it effectively and safely.
Training Goals and High Repetition Counts
High-repetition sets, such as those reaching 25 repetitions, are primarily intended to maximize muscular endurance and metabolic stress. Compared to the traditional 8–12 repetition range associated with maximal muscle growth, 25 reps fall into the domain of training for stamina. This allows the muscle to sustain force production over extended periods.
Physiologically, training with a high number of repetitions creates significant metabolic fatigue within the muscle fibers. This fatigue involves the accumulation of metabolites, which triggers a cellular signaling cascade that promotes muscle growth (hypertrophy) distinct from lifting heavier weights.
Research indicates that low-load resistance training (25 to 35 repetitions) can induce muscle size increases comparable to heavier, lower-rep training, provided the set is taken close to muscular failure. This style of training also improves local recovery by increasing capillary density, enhancing the delivery of oxygen and nutrients.
The Critical Factor of Weight Selection
The core determinant of whether a 25-rep set is effective is the amount of weight used. A 25-repetition set must be performed with a weight that makes the final few repetitions extremely challenging, requiring the set to be terminated close to momentary muscular failure. If the weight is too light, allowing 40 or 50 repetitions, the effort level is insufficient to stimulate significant adaptation.
Conversely, attempting 25 repetitions with a weight that should only allow 15 is excessively demanding and likely impossible without severe form degradation. For a true 25-repetition maximum (25RM), the load typically needs to be around 30% to 50% of your one-repetition maximum (1RM).
The effort level, often tracked by Reps in Reserve (RIR), should be low (RIR 0 to 2), indicating zero to two repetitions left in the tank. The goal is to reach a high level of effort despite using a lighter external load, which drives the desired physiological changes.
Avoiding Injury During High Volume Training
The extended duration of a 25-repetition set significantly increases the risk of technical failure due to accumulating fatigue. As the set progresses, the burning sensation from metabolite build-up can cause an involuntary shift in movement patterns. This breakdown in form places undue stress on joints and connective tissues, increasing the chance of an overuse injury.
To mitigate this risk, maintaining strict movement control and a consistent tempo is necessary, especially during the final, strenuous repetitions. If the technique begins to deteriorate significantly before the 25th repetition, the set should be immediately stopped. Implementing a gradual progression, where the volume is increased slowly over weeks, is also a foundational strategy for allowing the body’s tissues to adapt to the new demands.
Integrating 25 Reps into a Routine
Twenty-five-repetition sets are best suited for exercises that minimize joint stress under high fatigue. Isolation exercises, such as bicep curls, lateral raises, or triceps extensions, and movements performed on machines are ideal candidates for this high-volume approach. These exercises provide a stable environment where the target muscle can be worked to failure without requiring complex full-body coordination.
Heavy, unstable compound lifts like barbell squats or deadlifts are generally inappropriate for 25-rep sets because the risk of technical failure and subsequent injury outweighs the metabolic benefit. For overall programming, high-rep sets should be used strategically as an assistance movement, often placed at the end of a workout after heavier, lower-rep work. A common strategy involves alternating periods of high-load, low-volume training with periods of low-load, high-volume work to ensure a balanced stimulus for both strength and endurance adaptation.