This study investigated the effects of varying strength exercises and/or loading scheme on muscle cross-sectional area (CSA) and maximum strength after four strength training loading schemes: constant intensity and constant exercise (CICE), constant intensity and varied exercise (CIVE), varied intensity and constant exercise (VICE), varied intensity and varied exercise (VIVE). Forty-nine individuals were allocated into five groups: CICE, CIVE, VICE, VIVE, and control group (C). Experimental groups underwent a twice a week training for 12 weeks. Squat 1RM was assessed at baseline and after the training period. Whole quadriceps muscle and its heads CSA were also obtained pre- and post-training. The whole quadriceps CSA increased significantly (p<0.05) in all of the experimental groups from pre- to post-test in both the right and left legs: CICE: 11.6% and 12.0%; CIVE: 11.6% and 12.2%; VICE: 9.5% e 9.3% and VIVE: 9.9% and 11.6%, respectively. The CIVE and VIVE groups presented hypertrophy in all of the quadriceps muscle heads (p<0.05), while the CICE and VICE groups did not present hypertrophy in the vastus medialis and rectus femoris (RF), and in the RF muscles, respectively (p>0.05). The CIVE group had greater strength increments than the other training groups (Effect size confidence limit of the difference -ESCLdiff CICE: 1.41 - 1.56; VICE: 2.13 - 2.28; VIVE: 0.59 - 0.75). Our findings suggest: a) CIVE is more efficient to produce strength gains for physically active individuals; b) as long as the training intensity reaches an alleged threshold, muscle hypertrophy is similar regardless of the training intensity and exercise variation.
Alex’s notes: Keep the body confused. In order to grow and get stronger, there must be progressive overload of the musculature, but there must also be variation. Most of the time this variation is in the form of intensity and volume manipulation, but one could also change the exercise to a variation that still targets the desired muscle (squat and leg press for instance). This study looked at both these variables.
The subjects were resistance trained for at least six months, which makes them better than strict beginners but still makes the results less applicable to more experienced trainees. They all performed a 12-week, twice per week, hypertrophy-oriented strength training program targeting the legs. The training intensity was 6-10 maximal repetitions (RM) for all of the exercises performed and a 2-minute rest was allowed between sets while 3 minutes were respected between exercises. The constant intensity groups used an 8RM while the varied intensity used the 6-10RM range. The constant exercise used only the back squat, while the varied exercise also performed the leg-press, deadlift, and lunge.Notably, the training volume was equated across all of the experimental groups.
Although all groups experienced hypertrophy of the quadriceps, greater hypertrophy (about 2%) was noted in the varied exercise group. This minor difference in growth is likely because so long as the training intensity reaches an alleged threshold, whole muscle hypertrophy is similar regardless of the loading scheme and exercise variation. Moreover, only the varied exercise group showed growth in all the muscles of the quadriceps, which alone could account for the superiority of exercise variation on muscle growth. Maximum strength was also increased the greatest in the constant intensity, varied exercise group.
Varying exercises along the experimental period produces greater strength gains than variations in training intensity. Furthermore, it seems that varying training intensity and exercises, simultaneously, cannot be an appropriate strategy to increase maximum strength for physically active individuals.The data suggests that constant intensity training with varied exercises is more efficient to produce strength gains for physically active individuals. Remember that the subjects were beginner exercisers, and thus this study supports the notion that variations in training intensity are not critical to produce strength and muscle hypertrophy gains in the initial phase of a strength training program. Varying exercises during this phase seem to be more important to maximize the neural drive and, therefore, the functional adaptations.
So don’t just squat, but lunge, leg-press, and deadlift also.