Current strength training guidelines state that loads greater than 70% 1 repetition maximum (RM) are required to maximize adaptations in muscular strength and hypertrophy.
Similarly, it appears that gains in the muscular strength are optimal with loads of 1 to 5RM and the Hypertrophic gains are best achieved with loads of 6 to 12 RM.
These recommendations are based on the belief that heavy loads are necessary to recruit all muscle fibers responsible for promoting muscular adaptations. Even so, it remains debatable whether training with lighter loads is capable of recruiting all muscle fibers for a given set of reps.
Although the use of heavy loads seems necessary to maximize muscular adaptations, some researchers have alternatively postulated that training with intensities as low as 30% 1RM will ultimately result in complete recruitment of all fibers as long as the sets are performed to muscular failure.
Even so, it has been measured by electromyography that there are lower mean electrical amplitudes when training at low load intensities (<50% 1RM) versus high load intensities (>70% 1RM), even when sets are performed to muscle failure. . Still, there are studies that disagree with this.
What this study did was collect a number of studies in order to compare changes in strength and hypertrophy between training protocols with low and high loads.
To do this, they analyzed several studies with the following criteria:
- An experimental trial involving training of low load (≤60% 1RM) and high load training (>60% 1RM)
- All series up to muscle failure
- At least one method was used to estimate changes in muscle mass or dynamic strength
- The training protocol lasted a minimum of 6 weeks
- The study involved participants no medical conditions Known injuries or injuries that will affect training capacity
Which it was the result
The results of the force were somewhat contradictory depending on the test mode. Heavy loading showed a clear advantage for 1RM strength gains.
Considering that the essence of the 1RM test is to lift maximal loads, it logically follows that training closer to one’s RM would have the greatest transfer to this outcome. However, both heavy and light loads showed large effects on 1RM increases.
Data from direct measurements of muscle size indicate similar hypertrophic changes between high and low load conditions. Even so, it seems that it is better to train with heavy loads if we want to increase muscle mass.
Anyway, results indicate that both heavy and light loads can be equally effective to promote muscle growth as long as the training is carried out with a high level of effort.
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