Research Review: Greater Training Frequency = Greater Training Volume = Greater Strength Gains
Grgic J, Schoenfeld BJ, Davies TB, et al. Effect of Resistance Training Frequency on Gains in Muscular Strength: A Systematic Review and Meta-Analysis. Sports Med. Vol. 48, pp. 1207-1220, 2018.
Introduction
Muscular strength defines as the capacity to exert force under a particular set of biomechanical conditions. Engaging in resistance training (RT) can significantly increase muscular strength. RT variables, such as training volume, intensity, rest interval duration, exercise selection, training to muscular failure, exercise order, repetition velocity, and training frequency, are manipulated in an endeavor to maximize muscular adaptations. Of these variables, volume and load are most studied, while the potential of training frequency to influence increases in strength is often overlooked.
RT frequency refers to the number of training sessions performed per muscle group in a given time period. The common way to classify RT frequency is on a weekly basis. The current American College of Sports Medicine (ACSM) RT guidelines suggest that beginners train each muscle group two to three times per week using either a total-body or split-body (i.e. upper and lower body) routine. More advanced weight trainers use a split routine, in which one to three muscle groups are trained per training session. These recommendations are based on extrapolations from limited evidence and thus their practical applicability remains questionable.
A few studies suggest that the effects of RT frequency on muscular strength gains raise questions about the standard RT frequency recommendations.
The present research is the first systematic review of studies comparing different RT frequencies and their effects on muscular strength gains.
Purpose
The purpose of this research was threefold: (1) perform a systematic review of studies that compare influences of different RT frequencies on muscular strength outcomes; (2) quantify findings with a meta-analysis; and (3) draw evidence- based conclusions guiding exercise program design.
Methodology
The authors searched the English-language literature that included PubMed/MEDLINE, Scopus, and SPORTDiscus databases. In all of these databases, a search was performed from inception of indexing to June 1, 2017 by combining the following search terms: ‘resistance training frequency’, ‘weight training frequency’, ‘strength training frequency’, ‘strength’, ‘split training’, ‘workout frequency’, ‘split routine’, ‘split weight training’, ‘volume load’, ‘effects’. Boolean operators (AND, OR) were used to concatenate search terms. A secondary search was performed by screening the reference lists of the included studies and relevant review articles.
The final analysis comprised 49 treatment groups from 21 studies that were classified as moderate-to-good quality. The mean duration of RT programs was approximately 12 weeks (range 6–24 weeks), and the most common comparison of RT frequency was between two- and three-weekly training sessions (in 14 studies). The number of sets performed per exercise in individual studies during a training session varied from 1 to 18 sets. Twenty-one studies assessed dynamic muscular strength using 1-RM tests, and several included studies used both multi-joint and single-joint exercises for the 1-RM strength assessment.
This study used a Meta-analysis approach, a statistical approach that combines data from multiple studies to identify consistency among common treatment effects, or effect size, across studies. It represents a powerful tool to evaluate the effects, in this case different resistance-training frequencies, on strength development.
Results
The main results of this review suggest that there is a dose- response relationship between RT frequency and muscular strength gains; however, when training volume is equated, RT frequency becomes less important. The current body of evidence suggests that both training volume and frequency are major contributing factors to increase muscular strength. The authors acknowledge that there is a paucity of studies applying high RT frequencies, such as five or six training days per week, thereby opening an avenue for future research.
Conclusions
The results of this meta-analysis suggest a significant effect of RT frequency on muscular strength gain, with higher RT frequencies resulting in more strength gains. However, these effects seem to be primarily driven by training volume because when volume is equated, there was no significant effect of RT frequency on strength gains. It appears that from a practical standpoint, greater training frequencies might be used as a means of increasing total training volume, which may impact muscular strength gains. From the results of this study, it remains unclear whether RT frequency, on its own, has a significant effect on muscular strength gains.
Key Findings
- The results of the present analysis indicate a significant effect of resistance training (RT) frequency on gains in muscular strength, where higher training frequencies result in greater muscular strength gains.
- The effects of higher training frequencies seem to be primarily due to higher training volume because when the training volume is equated, this analysis found no significant effect of RT frequency on muscular strength gains.
- It is likely that trained individuals will use greater RT frequencies in their routines, and thus future research among this population is needed to draw more generalizable conclusions.