The Effects of Resistance Exercise Selection on Muscle Size and Strength in Trained Women

Abstract

The study compared the effects of resistance training programs composed by multi-joint (MJ), single-joint (SJ) and the combination of multi- and single-joint (MJ+SJ) exercises on muscle strength and hypertrophy in trained women. Thirty participants were divided into groups that performed only MJ exercises, SJ exercises and MJ+SJ exercises for six months. Participants were tested for 1-repetition maximum (RM) and muscle thickness (MT) before and after the intervention. All groups showed significant gains on 1RM tests from pre- to post-training (P<0.01). However, MJ and MJ+SJ groups obtained greater gains in 1RM for the MJ exercises in comparison with the SJ group. Increases in 1RM for the SJ exercises were similar among groups, with the exception of leg curl, where the SJ group obtained greater gains than MJ and MJ+SJ. All groups obtained significant increases in MT from pre- to post-training for all muscle groups. However, MJ and MJ+SJ groups presented greater increases in gluteus maximus, quadriceps femoris and pectoralis major in comparison with the SJ group. Therefore, our results suggest that, in general, performing MJ exercises seems to be necessary to obtain optimal results from a resistance training program; however SJ might be necessary to provide optimal strength gains in knee flexion.

Improbable data patterns in the work of Barbalho et al.

“…After performing 1,000,000 simulations, we observed that (A) none of the simulations had a perfect correlation between baseline squat and hip thrust 1RMs, and similarly, (B) none of the simulations had a perfectly homogeneous difference between squat and hip thrust 1RMs. This indicates that the perfect baseline relationship observed by Barbalho et al [73] has a P -value < 1 × 10 −6 .…”

“…Ignoring the probability of each group only having two val-249 ues, and the probability of such small ranges in the data, 250 simply attaining results with these characteristics ("runs" 251 of one number, followed by "runs" of another number) is 252 very unlikely, with probabilities of [73] (thin, colored bars) and the squat group average from [71] (thick, black bar). (B) This results in high z-scores for all three groups from [73] and the squat group average from [71], but especially so for those who performed multi-joint movements.…”

“…When adding the probability of the "runs" being arranged low-to-high in all four groups, the probability drops to approximately 1 in ten billion: Carlo simulations with the data simulated to be similar in nature to [73]. We incorporated the intraclass correlation coefficients (ICCs) for squat and hip thrust 1RMs reported by Barbalho et al [71], along with their uncertainties.…”

“…Variance( HT 1RM − SQ 1RM ) Frequency B Figure 10: Simulations reveal that observing a perfect baseline difference between squat and hip thrust 1RMs is highly improbable. We simulated data based on [73], taking into account the test-retest reliability of the squat and hip thrust [71]. These simulations created a reference distribution, against which we could assess how extreme the observation of a perfect difference in baseline squat and hip thrust 1RMs is.…”

“…The muscle thickness data in [73] have improbable distributions of even versus odd numbers ( Figure 12). In particular, there are no odd-valued pre-intervention muscle thicknesses in any group or muscle ( 0 /120, two-tailed P = 2(0.…”