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PURPOSE: This study investigated the effect of progressively adding sets for the lower limb every 2 wk versus performing a constant set volume in resistance-trained males. METHODS: Thirty-one resistance-trained males (age = 24.4 ± 2.9 yr, height = 175.5 ± 6.5 cm, body mass = 80.1 ± 9.4 kg, body fat = 14.4% ± 3.1%, resistance training [RT] experience = 5.1 ± 2.2 yr; one-repetition maximum [1RM] barbell back squat: body mass ratio = 1.7 ± 0.1 a.u.) were randomly allocated into a constant group (CG, n = 10), a four-set progression group (4SG, n = 10) or a six-set progression group (6SG, n = 11). After a 2-wk washout period and another 2-wk familiarization period, participants performed a lower-limb training program twice a week for 12 wk. Maximum dynamic strength (1RM) in the barbell back squat, vastus lateralis cross-sectional area, and the sum of lateral thigh muscle thickness at 30%, 50%, and 70% of the femur length were assessed at baseline and after the 12-wk training program. RESULTS: Regarding 1RM, multiple comparisons revealed that 6SG elicited higher muscle strength gains than 4SG ( P = 0.002) and CG ( P < 0.0001), and 4SG had greater improvements than CG ( P = 0.023). Cross-sectional area and sum of lateral thigh muscle thickness showed no between-group differences ( P = 0.067 and P = 0.076, respectively). However, an inspection of 95% confidence intervals suggests a potential dose-response relationship, with results appearing to plateau in the higher volume conditions. CONCLUSIONS: Our results suggest that progressively adding four or six sets per week every 2 wk elicited greater lower-limb strength in resistance-trained individuals over a 12-wk training period. Although our findings indicate a possible small benefit for higher volume conditions regarding hypertrophic adaptations in this population, the limited certainty of our findings warrants caution.

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Although used by resistance-trained individuals, it is unknown if increasing muscle strength prior to hypertrophy training leads to greater muscle growth and strength gains. We investigated muscle thickness and maximum strength in 26 resistance-trained men who were randomly assigned to either: STHT, consisted in a 3-week strength-oriented training period (4x1-3 repetition maximum [RM]) prior to a 5-week hypertrophy-oriented period (4x8-12RM), or HT, which comprised an 8-week hypertrophy-oriented training period. Vastus lateralis muscle thickness, and back squat and leg-press 1-RM were assessed at pre, third week, and after 8 weeks of training. When pre-to-post changes are compared, STHT induced greater muscle growth (p = 0.049; 95%CI = 0.15-3.2%; d = 0.81) and strength gains in the back squat (p = 0.015; 95%CI = 1.5-13%; d = 1.05) and leg-press 45° (p = 0.044; 95%CI = 0.16-9.9%; d = 0.79) compared to HT. Our results support the use of a period to increase muscle strength prior to an HT to increase muscle thickness and maximum strength in resistance-trained men.

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ABSTRACT: do Carmo, EC, De Souza, EO, Roschel, H, Kobal, R, Ramos, H, Gil, S, and Tricoli, V. Self-selected rest interval improves vertical jump postactivation potentiation. J Strength Cond Res 35(1): 91-96, 2021-This study compared the effects of self-selected rest interval (SSRI) and fixed rest interval (FRI) strategies on postactivation potentiation (PAP) in countermovement jump (CMJ) performance. Twelve strength-trained men (age: 25.4 ± 3.6 years; body mass: 78.8 ± 10.5 kg; height: 175 ± 7.0 cm; half-squat 1 repetition maximum: 188.7 ± 33.4 kg) performed 3 experimental conditions: (a) FRI: CMJ test; 4-minute rest interval; 5 repetition maximum (5RM) back squat; 4-minute rest interval; and CMJ test, (b) SSRI: CMJ test; 4-minute rest interval; 5RM back squat; SSRI; and CMJ test, and (c) control: CMJ test; 8-minute rest interval and CMJ test. In SSRI, subjects were instructed to rest until they felt fully recovered and able to exercise at maximal intensity based on the perceived readiness scale. Significant changes in pre-post CMJ performance were observed in the SSRI condition (38.2 ± 4.6 cm vs. 40.5 ± 4.4 cm; p = 0.08; confidence interval [CI]: 0.72-3.82 cm; effect size [ES] = 0.93). There were significant differences in post-CMJ performance when SSRI was compared with FRI (40.5 ± 4.4 cm vs. 37.7 ± 5.1 cm; p = 0.02; CI: 0.43-5.08; ES = 1.13) and control (40.5 ± 4.4 cm vs. 37.4 ± 5.7 cm; p = 0.01; CI: 0.66-5.61; ES = 1.35). The average rest interval length for the SSRI condition was 5:57 ± 2:44 min:sec (CI: 4:24-7:30). Our results suggest that the use of SSRI was an efficient and practical strategy to elicit PAP on CMJ height in strength-trained individuals.

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BACKGROUND: The present study investigated the effects of resistance training combined with ischemic preconditioning (IPC) on muscle size and strength in resistance-trained men. METHODS: Sixteen resistance-trained men were divided into two groups (Placebo and IPC) and trained twice a week for 6 weeks. Preconditioning protocols consisted of four, 5-min cycling bouts of ischemia/Placebo (250 or 10 mmHg, respectively) interspersed with 5 min of reperfusion (without pressure) alternated in each leg. Thirty minutes after the preconditioning protocol, participants performed 4 sets to concentric failure at 75% of one repetition-maximum (1-RM) in unilateral knee extension exercise. Muscle thickness (ultrasound) and 1RM were assessed at baseline and 72 hours after the last training session. ANCOVA was used to compare muscle thickness and 1RM changes, using muscle thickness and 1-RM baseline values, respectively, as covariates. Significance level was set at P<0.05. RESULTS: Average of number of repetitions was higher in IPC compared to Placebo (13±4 and 11±2, respectively; P=0.0002). Muscle thickness did not change in either group from pre- to post-6 weeks (P=0.32). IPC improved 1-RM more than Placebo (P=0.04). CONCLUSIONS: IPC may augment greater strength gains in resistance-trained men due to an increase in training volume.

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Evangelista, AL, De Souza, EO, Moreira, DCB, Alonso, AC, Teixeira, CVLS, Wadhi, T, Rauch, J, Bocalini, DS, Pereira, PEDA, and Greve, JMDA. Interset stretching vs. traditional strength training: effects on muscle strength and size in untrained individuals. J Strength Cond Res 33(7S): S159-S166, 2019-This study compared the effects of 8 weeks of traditional strength training (TST) and interset stretching (ISS) combined with TST on muscular adaptations. Twenty-nine sedentary, healthy adults were randomly assigned to either the TST (n = 17; 28.0 ± 6.4 years) or ISS (n = 12; 26.8 ± 6.1 years) group. Both groups performed 6 strength exercises encompassing the whole body (bench press, elbow extension, seated rows, biceps curl, knee extension, and knee flexion) performing 4 sets of 8-12 repetition maximum (RM) with a 90-second rest between sets. However, the ISS group performed static passive stretching, at maximum amplitude, for 30 seconds between sets. Both groups performed training sessions twice a week on nonconsecutive days. Muscle strength (i.e., 1RM) and hypertrophy (i.e., muscle thickness [MT] by ultrasonography) were measured at pre-test and after 8 weeks of training. Both groups increased 1RM bench press (p ≤ 0.0001): ISS (23.4%, CIdiff: 4.3 kg-11.1 kg) and TST (22.2%, CIdiff: 5.2 kg-10.9 kg) and 1RM knee extension (p ≤ 0.0001): ISS (25.5%, CIdiff: 5.6 kg-15.0 kg) and TST (20.6%, CIdiff: 4.4 kg-12.3 kg). Both groups increased MT of biceps brachii (BIMT), triceps brachii (TRMT), and rectus femoris (RFMT) (p ≤ 0.0001). BIMT: ISS (7.2%, CIdiff: 1.14-3.5 mm) and TST (4.7%, CIdiff: 0.5-2.5 mm), TRMT: ISS (12.3%, CIdiff: 1.1-4.4 mm) and TST (7.1%, CIdiff: 0.3-3.1 mm), and RFMT: ISS (12.4%, CIdiff: 1.1-2.9 mm) and TST (9.1%, CIdiff: 0.7-2.2 mm). For vastus lateralis muscle thickness (VLMT) and sum of the 4 muscle thickness sites (ΣMT), there was a significant group by time interaction (p ≤ 0.02) in which ISS increased VLMT and ΣMT to a greater extent than TST. Vastus lateralis muscle thickness: ISS (17.0%, CIdiff: 1.5-3.1 mm) and TST (7.3%, CIdiff: 0.7-2.1 mm), and ΣMT: ISS (10.5%, CIdiff: 6.5-9.0 mm) and TST (6.7%, CIdiff: 3.9-8.3 mm). Although our findings might suggest a benefit of adding ISS into TST for optimizing muscle hypertrophy, our data are not sufficient enough to conclude that ISS is superior to TST for inducing muscle hypertrophic adaptations. More studies are warranted to elucidate the effects of ISS compared with TST protocols on skeletal muscle. However, our findings support that adding ISS to regular TST regimens does not compromise muscular adaptations during the early phase of training (<8 weeks) in untrained individuals.

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This case report assessed quality of life, activities of daily living, motor symptoms, functional ability, neuromuscular parameters and mRNA expression of selected genes related to muscle protein synthesis and degradation in a patient with Multiple System Atrophy (MSA). The patient underwent resistance training with instability devices (i.e., bosu, dyna disk, balance disk, Swiss ball) for six months twice a week. After the six months training, the patient's left and right quadriceps muscle cross-sectional area and leg press one-repetition maximum increased 6.4%, 6.8%, and 40%, respectively; the patient's timed up and go, sit to stand, dynamic balance, and activities of daily living improved 33.3%, 28.6%, 42.3%, and 40.1%, respectively; the patient's severity of motor symptoms and risk of falls decreased 32% and 128.1%, respectively. Most of the subscales of quality of life demonstrated improvements as well, varying from 13.0% to 100.0%. mRNA expression of mechanogrowth factor and mammalian target of rapamycin increased 12.7-fold and 1.5-fold, respectively. This case report describes likely the first nonpharmacological therapeutic tool that might be able to decrease the severity of motor symptoms and risk of falls, and to improve functional ability, neuromuscular parameters, and quality of the life in a patient with MSA. Key pointsSix months of resistance training with instability alleviate the MSA-related effects and improve the quality of life in a patient with MSA.High complexity exercise intervention (i.e., resistance training with instability) may be very beneficial to individuals with impaired motor control and function as MSA patients.Caution should be exercised when interpreting our findings as they cannot be generalized to the entire MSA population and they do not allow establishing causal conclusions on the effects of this mode of exercise on MSA.

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UNLABELLED: This study compared quadriceps muscle cross-sectional area (CSA) and maximum strength (1RM) after three different short-term strength training (ST) regimens (i.e. non-periodized [NP], traditional-periodization [TP], and undulating-periodization [UP]) matched for volume load in previously untrained individuals. Thirty-one recreationally active males were randomly divided into four groups: NP: n = 9; TP: n = 9; UP: n = 8 and control group (C): n = 5. Experimental groups underwent a 6-week program consisting of two training sessions per week. Muscle strength was assessed at baseline and after the training period. Dominant leg quadriceps CSA was obtained through magnetic resonance imaging (MRI) at baseline and 48h after the last training session. RESULTS: The 1RM increased from pre to post only in the NP and UP groups (NP = 17.0 %, p = 0.002; UP = 12.9 %, p = 0.03), respectively. There were no significant differences in 1RM for LP and C groups after 6 weeks (TP = 7.7 %, p = 0.58, C = 1.2 %, p = 1.00). The CSA increased from pre to post in all of the experimental groups (NP = 5.1 %, p = 0.0001; TP = 4.6 %, p = 0.001; UP = 5.2 %, p = 0.0001), with no changes observed in the C group (p = 0.93). CONCLUSION: Our results suggest that different ST periodization regimens over a short-term (i.e. 6 weeks), volume load equated conditions seem to induce similar hypertrophic responses regardless of the loading scheme employed. In addition, for those recreational males who need to develop muscle strength in the short-term, the training regimen should be designed properly. Key pointsMuscle hypertrophy occurs within six weeks in recreationally active men regardless the ST training regimen employed.When the total volume is similar, training at greater intensities will demonstrate superior gains in the 1RM performance.Some caution should be exercised when interpreting our findings since long-term periodized regimens could produce different training-induced responses.

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This study investigated the effects of varying strength exercises and loading scheme on muscle cross-sectional area (CSA) and maximum strength after 4 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 5 groups: CICE, CIVE, VICE, VIVE, and control group (C). Experimental groups underwent twice a week training for 12 weeks. Squat 1 repetition maximum was assessed at baseline and after the training period. Whole quadriceps muscle and its heads CSA were also obtained pretraining and posttraining. The whole quadriceps CSA increased significantly (p ≤ 0.05) in all of the experimental groups from pretest to posttest 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), whereas 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.

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The present study aimed to determine the concurrent validity of ultrasound (US) measurement of the vastus lateralis muscle (VL) cross-sectional area (CSA) having magnetic resonance imaging (MRI) as the gold standard measurement, in a heterogeneous sample of participants. Thirty-one individuals (52.44 ± 16.37 years; 1.67 ± 0.11 m; 75.25 ± 13.82 kg) volunteered to participate in the study. All the images were performed in the right leg. Image-fitting technique (US) and computerized planimetry technique (US and MRI) were used to determine the VL CSA. The typical error (TE) of measurement was used to determine the concurrent validity of the US measurements. Our results demonstrated good validity of the US compared with the MRI measurements (TE = 0.37 cm; coefficient of variation = 1.75%). The Bland-Altman plot demonstrated bias of 0.07 ± 0.53 cm and limits of agreement of 0.96-1.11 cm. Based on our TE, bias and limits of agreement, we concluded that the US image-fitting technique is valid to assess the VL CSA in a heterogeneous sample of participants. Thereby, US can be used instead of MRI to assess changes in skeletal muscle morphology.

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It has been suggested that muscle tension plays a major role in the activation of intracellular pathways for skeletal muscle hypertrophy via an increase in mechano growth factor (MGF) and other downstream targets. Eccentric exercise (EE) imposes a greater amount of tension on the active muscle. In particular, high-speed EE seems to exert an additional effect on muscle tension and, thus, on muscle hypertrophy. However, little is known about the effect of EE velocity on hypertrophy signaling. This study investigated the effect of acute EE-velocity manipulation on the Akt/mTORCI/p70(S6K) hypertrophy pathway. Twenty subjects were assigned to either a slow (20°·s(-1); ES) or fast EE (210°·s(-1); EF) group. Biopsies were taken from vastus lateralis at baseline (B), immediately after (T1), and 2 h after (T2) the completion of 5 sets of 8 repetitions of eccentric knee extensions. Akt, mTOR, and p70(S6K) total protein were similar between groups, and did not change postintervention. Further, Akt and p70(S6K) protein phosphorylation were higher at T2 than at B for ES and EF. MGF messenger RNA was similar between groups, and only significantly higher at T2 than at B in ES. The acute manipulation of EE velocity does not seem to differently influence intracellular hypertrophy signaling through the Akt/mTORCI/p70S6K pathway.

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