Muscle Hypertrophy: A Narrative Review on Training Principles for Increasing Muscle Mass

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This article reviews the current body of literature related to training considerations for increasing muscle hypertrophy in young healthy adults.

In particular, this article discusses the following foundational factors that should influence a coach’s decisionmaking when designing resistance training programs for increasing muscle size:

  • Training volume
  • Load
  • Training frequency
  • Training to momentary muscular failure
  • Exercise variation
  • Contraction type
  • Exercise order
  • Repetition tempo
  • Interset recovery

Training volume

Resistance training volume, described as the amount of work completed for any given unit of time. Muscle hypertrophy is enhanced after high volume longitudinal programs, particularly when multiple sets are used, rather than single set routines. Radaelli et al. showed that 5 sets of exercises per training session resulted in significantly greater upper arm development when compared to one and 3 set routines, across a 6-month training period.

It is important to emphasize that the relationship between volume and muscle growth is unlikely to be linear. That is; continual increases in training volume would inevitably lead to a plateau in the development of muscle mass. This concept is supported by the recent findings of Amirthalingham et al. (3). In their investigation, no significant difference in muscle hypertrophy was found between subjects who performed either 5 sets of 10 repetitions or 10 sets of 10 repetitions over a 6-week period


The manipulation of load during resistance training, which is typically presented as the percentage of maximal load that can be used for any given movement, has been proposed as a vital factor in maximizing muscle hypertrophy. Mitchell et al. (51) showed that a low-load training (30% 1RM) regime resulted in similar increases in whole muscle cross-sectional area when compared to high-load training (80% 1RM) over a 10-week period. Furthermore, using a moderate loading scheme (8–12RM) or a variety of training loads (2–4RM, 8–12RM and 20–30RM) across a training week has been shown to result in similar increases in muscle mass after an 8-week intervention (71). Therefore, when coaches are prescribing a training stimulus for muscle hypertrophy, high loads or low loads may be selected. Traditionally, loads .65% 1RM have been prescribed for hypertrophy programs, which might not be necessary. This information might also be useful for injury rehabilitation, where low-load training can be an effective method to increase muscle mass without the augmented forces associated with high-load training, leading to reduced joint loads

Training frequency

Training frequency is defined as the number of training sessions per unit of time. For the majority of resistance-trained athletes, it is inevitable that the training volume per session and training frequency are inversely related, such that an increase in training frequency leads to a reduction in volume per session. In the case of a high-frequency training program, where a muscle group is trained on multiple occasions, the training volume for each session should be lower to prevent excessive weekly training volumes. High training frequency should be periodized strategically, so that adequate recovery is provided between sessions

Training to momentary muscular failure

When training to failure, it is hypothesized that maximal motor unit recruitment is achieved resulting in the fatigue of a greater number of muscle fibers (16,97), in turn leading to a greater hypertrophic response. Sundstrup et al. (86) reported that complete concentric failure was not required to achieve full muscle activation using EMG analysis, with a plateau occurring during the final 3–5 repetitions with a 15RM load. This is an important consideration because routinely performing resistance training to failure may produce symptoms of overtraining and subsequent threats to the anabolic status of athletes

Exercise variation

Within this investigation, hypertrophy of the vastus medialis and rectus femoris was more for subjects who varied exercises over 3-week cycles, compared to subjects who used the same exercise throughout. This suggests that to maximize hypertrophic adaptation, it is necessary to stress the muscle across its different portions (proximaldistal) using a variety of exercises.

Contraction type

In a recent meta-analysis, Schoenfeld et al. (76) identified a nonsignificant trend that eccentric-only training induced greater hypertrophic adaptations than concentric-only concentric training for inducing hypertrophic gains (P 5 0.076). Mean effect sizes for muscle growth after eccentriconly and concentric-only training were 1.02 and 0.77 respectively, with an effect size difference of 0.27. The authors propose that because of many of the studies included for analysis matching the total repetitions performed and not total work, the higher amount of work completed was likely to be a major influence on these findings.

Exercise order

It is generally recommended that multijoint exercises, relying on work being produced by large muscle groups, should be performed in the initial stages of a training session. It is possible that using multijoint exercises at the start of a training session will result in greater hypertrophic adaptations in larger muscle groups.

One issue with performing single-joint exercises before multijoint exercises is that the prefatigued muscle may alter the muscle activation patterns during the multijoint exercise

Repetition tempo

Explosive strength training demonstrates a clear advantage over slow concentric training for strength development. This is likely to be due to the higher forces that are required to increase acceleration during the concentric phase of an appropriately loaded lift


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