5. Evidence Based Recommendations

This chapter will address the influence that various training program parameters (variables) have on the effectiveness on a training program. The program variables that seem to have an effect on the training responses are (ACSM 2009, Fisher et al. 2013, Schoenfeld 2016):

The order of discussion in this chapter goes from general (e.g., how often one can or wants to train) to more specific (which exercises to use). However, it is important to note that the various parameters are not independent: for instance, many sets and heavy weights per training session require less frequent training sessions. The focus of this chapter is on hypertrophy, but strength is also discussed in a smaller degree.

Evidence-based recommendations follow (see also Fisher et al. 2011, 2013, Schoenfeld 2016), but the interplay among the variables will be discussed in Chapter 11. Evidence-based medicine and exercise science has become the norm in recent years and it is generally accepted that any treatment should be based on the best available evidence gained from the scientific method (Arnold and Schilling 2017).

The evaluation was mainly based on review studies or meta-analyses (aggregations of information from many studies leading to a higher statistical power and more robust point estimates). It should be noted however that a common criticism of meta-analyses is that they can be largely influenced by the methodological differences of the studies included (Gentil et al. 2017b).

Frequency (of training sessions or per muscle group)

Definitions: The term frequency in the literature usually refers to the number of training sessions (workouts) per week. Sometimes it can also refer to the times certain exercises or muscle groups are trained per week. The two definitions are different and in this book the terms muscle group training frequency and training sessions frequency will be used to distinguish between them. Example of two training programs: in the first one, the athlete trains the entire body twice a week, while in the second one he trains 6 times per week dividing (splitting) the body in 3 parts. These two programs have the same “muscle group training frequency” of 2, but in the first program the “training sessions frequency” is 2, while in the second is 6.

Theory: A muscle should be trained when it has fully recovered and is slightly “stronger”. In molecular levels, as discussed in Chapter 4, metabolic (e.g., glycogen), mechanical (e.g. protein synthesis), neural and hormonal adaptations of non-damaged muscles take place within 1-3 days.

Research (frequency per muscle group): Studies with trained persons show that recovery after resistance training with typical training protocols takes place within 2-3 days for 70-80% of the subjects (Bishop et al. 2008, Korak et al. 2015) with maximal recovery after 3-4 days (McLester et al. 2003). For older persons (>50 years), it can take more than 4 days for 70% of the person to recover (Bishop et al. 2008).

Strength: Studies with trained men showed that “muscle group training frequency” of 2 or 3 times per week yielded better strength results compared to once a week, with no apparent further advantage of three versus two sessions (Peterson et al. 2004). A meta-analysis focusing on strength improvements found that for untrained and trained individuals, frequencies of 3 and 2 times per week respectively gave the best (strength) results (Rhea et al. 2003, Tzur and Roberts 2017). However, in each of the above reviews, the total weekly volumes (sets × repetitions × resistance) between the groups were not matched.

Hypertrophy: A review of various studies found no statistically significant difference in the daily rate of change of quadriceps size between “muscle group training frequencies” of two and three for untrained men and women (Wernbom et al. 2007). A review of frequency studies equating total weekly training volume (sets × repetitions × resistance) indicated that frequencies of training twice per week promote superior hypertrophic outcomes compared to training once a week for both trained and untrained individuals (Schoenfeld et al. 2016a). It should be mentioned however, that other recent studies (not included in the previous reviews) showed no differences between 1 or 1.5 and 3 “muscle group frequencies” per week for trained persons (Thomas and Burns 2016, Crewther et al. 2016).

Research (frequency of training sessions): Keeping the “muscle group training frequency” constant at twice per week and increasing the “training sessions frequency” (from 2 to 4 or from 4 to 6 sessions per week) did not reveal significant differences in body composition or strength gains of untrained women (Calder et al. 1994) or professional drug-free bodybuilders (Ribeiro et al. 2016). Similarly, the division of daily training loads of elite weightlifters into 2 small sessions (morning and evening) did not have an effect on muscle hypertrophy but was more favorable for neural adaptations leading to increased strength development (Häkkinen and Pakarinen 1991, Hartman 2007). The effect however, was not statistically significant.