Resistance Training Frequencies of 3 and 6 Times Per Week Produce Similar Muscular Adaptations in Resistance-Trained Men

Maximal Number of Repetitions at Percentages of the One Repetition Maximum: A Meta-Regression and Moderator Analysis of Sex, Age, Training Status, and Exercise

The maximal number of repetitions that can be completed at various percentages of the one repetition maximum (1RM) [REPS ~ %1RM relationship] is foundational knowledge in resistance exercise programming. The current REPS ~ %1RM relationship is based on few studies and has not incorporated uncertainty into estimations or accounted for between-individuals variation. Therefore, we conducted a meta-regression to estimate the mean and between-individuals standard deviation of the number of repetitions that can be completed at various percentages of 1RM. We also explored if the REPS ~ %1RM relationship is moderated by sex, age, training status, and/or exercise. A total of 952 repetitions-to-failure tests, completed by 7289 individuals in 452 groups from 269 studies, were identified. Study groups were predominantly male (66%), healthy (97%), < 59 years of age (92%), and resistance trained (60%). The bench press (42%) and leg press (14%) were the most commonly studied exercises. The REPS ~ %1RM relationship for mean repetitions and standard deviation of repetitions were best described using natural cubic splines and a linear model, respectively, with mean and standard deviation for repetitions decreasing with increasing %1RM. More repetitions were evident in the leg press than bench press across the loading spectrum, thus separate REPS ~ %1RM tables were developed for these two exercises. Analysis of moderators suggested little influences of sex, age, or training status on the REPS ~ %1RM relationship, thus the general main model REPS ~ %1RM table can be applied to all individuals and to all exercises other than the bench press and leg press. More data are needed to develop REPS ~ %1RM tables for other exercises.

Effect of different training frequencies on maximal strength performance and muscle hypertrophy in trained individuals-a within-subject design

Several studies comparing resistance training (RT) frequencies may have been affected by the large between-subject variability. This study aimed to compare the changes in lower limbs maximal dynamic strength (1RM) and quadriceps femoris cross-sectional area (CSA) after a RT with different weekly frequencies in strength-trained individuals using a within-subject design. Twenty-four men participated in a 9-week RT program, being randomly divided into two conditions: resistance training with equalized total training volume (RTEV) and with unequalized total training volume (RTUV). The RT protocol used the unilateral leg press 45° exercise and each subject’s lower limb executed one of the proposed frequencies (one and three times/week). All conditions effectively increased 1RM and CSA (p<0.001); however, no significant differences were observed in the values of 1RM (p = 0.454) and CSA (p = 0.310) between the RT frequencies in the RTEV and RTUV conditions. Therefore, RT performed three times a week showed similar increases in 1RM and CSA to the program performed once a week, regardless of training volume equalization. Nevertheless, when the higher RT frequency allowed the application of a greater TTV (i.e., RTUV), higher effect size (ES) values (0.51 and 0.63, 1RM and CSA, respectively) were observed for the adaptations.

Greater effects by performing a small number of eccentric contractions daily than a larger number of them once a week

Our previous study found that one maximal voluntary eccentric contraction (MVC-ECC) performed daily for five days a week for four weeks increased MVC-ECC, isometric (MVC-ISO), and concentric contraction (MVC-CON) torque of the elbow flexors more than 10%. The present study investigated the effects of six maximal voluntary eccentric contractions on the MVC torques and biceps brachii and brachialis muscle thickness (MT). Thirty-six healthy young adults were placed to one of the three groups (N=12 per group); the 6×1 group that performed one set of six contractions once a week, the 6×5 group that performed one set of six contractions a day for 5 days a week, and the 30×1 group that performed five sets of six contractions a day in a week. The training duration was 4 weeks for all groups, and changes in MVC-ECC, MVC-CON and MVC-ISO torque, and MT before and after the 4-week training were compared among the groups. The 6×1 group did not show significant changes in muscle strength and MT. Significant (p>0.05) increases in MVC-ECC (13.5±11.5%), MVC-ISO (9.3±5.5%), MVC-CON torque (11.1±7.4%) were evident for the 6×5 group only, and increases in MT were found for the 6×5 (10.4±4.4%) and 30×1 (8.0±5.8%) groups without a significant difference. These results suggest that performing a small number of eccentric contractions five days a week is more effective for increasing muscle strength than performing a larger volume of eccentric contractions once a week. However, it appears that training volume is a factor for muscle hypertrophy in a short-term training.

Equal-Volume Strength Training With Different Training Frequencies Induces Similar Muscle Hypertrophy and Strength Improvement in Trained Participants

The main goal of the current study was to compare the effects of volume-equated training frequency on gains in muscle mass and strength. In addition, we aimed to investigate whether the effect of training frequency was affected by the complexity, concerning the degrees of freedom, of an exercise. Participants were randomized to a moderate training frequency group (two weekly sessions) or high training frequency group (four weekly sessions). Twenty-one participants (male: 11, female: 10, age: 25.9 ± 4.0) completed the 9-week whole-body progressive heavy resistance training intervention with moderate (n = 13) or high (n = 8) training frequency. Whole-body and regional changes in lean mass were measured using dual-energy x-ray absorptiometry, while the vastus lateralis thickness was measured by ultrasound. Changes in muscle strength were measured as one repetition maximum for squat, hack squat, bench press, and chest press. No differences between groups were observed for any of the measures of muscle growth or muscle strength. Muscle strength increased to a greater extent in hack squat and chest press than squat and bench press for both moderate (50 and 21% vs. 19 and 14%, respectively) and high-frequency groups (63 and 31% vs. 19 and 16%, respectively), with no differences between groups. These results suggest that training frequency is less decisive when weekly training volume is equated. Further, familiarity with an exercise seems to be of greater importance for strength adaptations than the complexity of the exercise.

A Systematic Review Examining the Approaches Used to Estimate Interindividual Differences in Trainability and Classify Individual Responses to Exercise Training

Background: Many reports describe statistical approaches for estimating interindividual differences in trainability and classifying individuals as "responders" or "non-responders." The extent to which studies in the exercise training literature have adopted these statistical approaches remains unclear. Objectives: This systematic review primarily sought to determine the extent to which studies in the exercise training literature have adopted sound statistical approaches for examining individual responses to exercise training. We also (1) investigated the existence of interindividual differences in trainability, and (2) tested the hypothesis that less conservative thresholds inflate response rates compared with thresholds that consider error and a smallest worthwhile change (SWC)/minimum clinically important difference (MCID). Methods: We searched six databases: AMED, CINAHL, EMBASE, Medline, PubMed, and SportDiscus. Our search spanned the aerobic, resistance, and clinical or rehabilitation training literature. Studies were included if they used human participants, employed standardized and supervised exercise training, and either: (1) stated that their exercise training intervention resulted in heterogenous responses, (2) statistically estimated interindividual differences in trainability, and/or (3) classified individual responses. We calculated effect sizes (ES_IR) to examine the presence of interindividual differences in trainability. We also compared response rates (n = 614) across classification approaches that considered neither, one of, or both errors and an SWC or MCID. We then sorted response rates from studies that also reported mean changes and response thresholds (n = 435 response rates) into four quartiles to confirm our ancillary hypothesis that larger mean changes produce larger response rates. Results: Our search revealed 3,404 studies, and 149 were included in our systematic review. Few studies (n = 9) statistically estimated interindividual differences in trainability. The results from these few studies present a mixture of evidence for the presence of interindividual differences in trainability because several ES_IR values lay above, below, or crossed zero. Zero-based thresholds and larger mean changes significantly (both p < 0.01) inflated response rates. Conclusion: Our findings provide evidence demonstrating why future studies should statistically estimate interindividual differences in trainability and consider error and an SWC or MCID when classifying individual responses to exercise training. Systematic Review Registration: [website], identifier [registration number].

Effects of Variations in Resistance Training Frequency on Strength Development in Well-Trained Populations and Implications for In-Season Athlete Training: A Systematic Review and Meta-analysis

BACKGROUND

In-season competition and tournaments for team sports can be both long and congested, with some sports competing up to three times per week. During these periods of time, athletes need to prepare technically, tactically and physically for the next fixture and the short duration between fixtures means that, in some cases, physical preparation ceases, or training focus moves to recovery as opposed to progressing adaptations.

OBJECTIVE

The aim of this review was to investigate the effect of training frequency on muscular strength to determine if a potential method to accommodate in-season resistance training, during busy training schedules, could be achieved by utilizing shorter more frequent training sessions across a training week.

METHODS

A literature search was conducted using the SPORTDiscus, Ovid, PubMed and Scopus databases. 2134 studies were identified prior to application of the following inclusion criteria: (1) maximal strength was assessed, (2) a minimum of two different training frequency groups were included, (3) participants were well trained, and finally (4) compound exercises were included within the training programmes. A Cochrane risk of bias assessment was applied to studies that performed randomized controlled trials and consistency of studies was analysed using I² as a test of heterogeneity. Secondary analysis of studies included Hedges' g effect sizes (g) and between-study differences were estimated using a random-effects model.

RESULTS

Inconsistency of effects between pre- and post-intervention was low within-group (I² = 0%), and moderate between-group (I² ≤ 73.95%). Risk of bias was also low based upon the Cochrane risk of bias assessment. Significant increases were observed overall for both upper (p ≤ 0.022) and lower (p ≤ 0.008) body strength, pre- to post-intervention, when all frequencies were assessed. A small effect was observed between training frequencies for upper (g ≤ 0.58) and lower body (g ≤ 0.45).

CONCLUSION

Over a 6-12-week period, there are no clear differences in maximal strength development between training frequencies, in well-trained populations. Such observations may permit the potential for training to be manipulated around competition schedules and volume to be distributed across shorter, but more frequent training sessions within a micro-cycle rather than being condensed into 1-2 sessions per week, in effect, allowing for a micro-dosing of the strength stimuli.

Effects of different resistance training frequencies on body composition and muscular performance adaptations in men

BACKGROUND

The aim of this study was to compare the effects of 8 weeks resistance training (RT) with two sessions versus four sessions per week under volume load-equated conditions on body composition, maximal strength, and explosive actions performance in recreationally trained men.

METHODS

Thirty-five healthy young men participated in the study and were randomly divided into a two sessions per-week RT (RT2, n = 12), four sessions per-week RT (RT4, n = 13) or a control group (CG, n = 10). All subjects were evaluated for thigh, chest and arm circumference, countermovement jump (CMJ), medicine ball throw (MBT), 1-repetition maximum (1RM) leg press, bench press, arm curl, muscular endurance (i.e., 60% of 1RM to failure) for leg press, and bench press at pre, mid (week 4) and post an 8-week training intervention.

RESULTS

A two-way analysis of variance with repeated measures (3 [group] × 3 [time]) revealed that both training groups increased chest and thigh circumferences, strength and explosive actions performance tests in comparison to CG following 8 weeks of training (p = 0.01 to 0.04). Group × time interactions were also noted in 1RM bench press (effects size [ES] = 1.07 vs. 0.89) and arm curl (ES = 1.15 vs. 0.89), with greater gains for RT4 than RT2 (p = 0.03).

CONCLUSION

RT improved muscle strength, explosive actions performance and markers of muscle size in recreationally trained men; however, four sessions of resistance training per week produced greater gains in muscular strength for the upper body measures (i.e., 1RM bench press and arm curl) when compared to two sessions per week under volume-equated conditions.

Equating Resistance-Training Volume Between Programs Focused on Muscle Hypertrophy

Calculating resistance-training volume in programs focused on muscle hypertrophy is an attempt to quantify the external workload carried out, then to estimate the dose of stimulus imposed on targeted muscles. The volume is usually expressed in some variables that directly affected the total training work, such as the number of sets, repetitions, and volume-load. These variables are used to try to quantify the training work easily, for the subsequent organization and prescription of training programs. One of the main uses of measures of volume quantification is seen in studies in which the purpose is to compare the effects of different training protocols on muscle growth in a volume-equated format. However, it seems that not all measures of volume are always appropriate for equating training protocols. In the current paper, it is discussed what training volume is and the potentials and shortcomings of each one of the most common ways to equate it between groups depending on the independent variable to be compared (e.g., weekly frequency, intensity of load, and advanced techniques).

Effects of Resistance Training on Muscle Size and Strength in Very Elderly Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Effects of resistance training on muscle strength and hypertrophy are well established in adults and younger elderly. However, less is currently known about these effects in the very elderly (i.e., 75 years of age and older).

OBJECTIVE

To examine the effects of resistance training on muscle size and strength in very elderly individuals.

METHODS

Randomized controlled studies that explored the effects of resistance training in very elderly on muscle strength, handgrip strength, whole-muscle hypertrophy, and/or muscle fiber hypertrophy were included in the review. Meta-analyses of effect sizes (ESs) were used to analyze the data.

RESULTS

Twenty-two studies were included in the review. The meta-analysis found a significant effect of resistance training on muscle strength in the very elderly [difference in ES = 0.97; 95% confidence interval (CI) 0.50, 1.44; p = 0.001]. In a subgroup analysis that included only the oldest-old participants (80 + years of age), there was a significant effect of resistance training on muscle strength (difference in ES = 1.28; 95% CI 0.28, 2.29; p = 0.020). For handgrip strength, we found no significant difference between resistance training and control groups (difference in ES = 0.26; 95% CI - 0.02, 0.54; p = 0.064). For whole-muscle hypertrophy, there was a significant effect of resistance training in the very elderly (difference in ES = 0 30; 95% CI 0.10, 0.50; p = 0.013). We found no significant difference in muscle fiber hypertrophy between resistance training and control groups (difference in ES = 0.33; 95% CI - 0.67, 1.33; p = 0.266). There were minimal reports of adverse events associated with the training programs in the included studies.

CONCLUSIONS

We found that very elderly can increase muscle strength and muscle size by participating in resistance training programs. Resistance training was found to be an effective way to improve muscle strength even among the oldest-old.

Performing Repetitions to Failure in Lower-Limb Single-Joint Exercise Does Not Reduce Countermovement Jump Performance in Trained Male Adults

Performing repetitions to failure (RF) is a strategy that might acutely reduce neuromuscular performance, as well as increase the rating of perceived exertion (RPE) and the internal training load (ITL) during and after a resistance training (RT) session. Thus, this study aimed to analyze the acute effects of RF or repetitions not to failure (RNF) on countermovement jump (CMJ) performance and the ITL in trained male adults. Eleven men performed two experimental protocols in randomized order (RF vs. RNF). Under the RF condition, participants performed three sets of the leg extension exercise using 100% of the 10RM load and rest intervals of 180-s between sets. Under the RNF condition, participants were submitted to six sets of five repetitions with the same intensity and an 80-s rest interval between sets in the same exercise. The CMJ test was analyzed before and following (15-s and 30-min, respectively) each experimental session. The ITL was evaluated by multiplying the RPE and the total session time, 30-min after the protocol. No main effect or interaction time vs. condition was found for CMJ performance (p > 0.05). In contrast, the ITL showed higher values under the RF condition (p = 0.003). Therefore, even though RF-induced a greater ITL, our results suggest that adopting this strategy in one single-joint exercise for the lower limbs does not seem sufficient to reduce CMJ height.

Effects of training frequency on muscular strength for trained men under volume matched conditions

Background

In resistance training, the role of training frequency to increase maximal strength is often debated. However, the limited data available does not allow for clear training frequency “optimization” recommendations. The purpose of this study was to investigate the effects of training frequency on maximal muscular strength and rate of perceived exertion (RPE). The total weekly training volume was equally distributed between two and four sessions per muscle group.

Methods

Twenty-one experienced resistance-trained male subjects (height: 1.85 ± 0.06 m, body mass: 85.3 ± 12.3 kg, age: 27.6 ± 7.6 years) were tested prior to and after an 8-week training period in one-repetition maximum (1RM) barbell back squat and bench press. Subjects were randomly assigned to a SPLIT group (n = 10), in which there were two training sessions of squats and lower-body exercises and two training sessions of bench press and upper-body exercises, or a FULLBODY group (n = 11), in which four sessions with squats, bench press and supplementary exercises were conducted every session. In each session, the subjects rated their RPE after barbell back squat, bench press, and the full session.

Results

Both groups significantly increased 1RM strength in barbell back squat (SPLIT group: +13.25 kg; FULLBODY group: +14.31 kg) and bench press (SPLIT group: +7.75 kg; FULLBODY group: +8.86 kg) but training frequency did not affect this increase for squat (p = 0.640) or bench press (p = 0.431). Both groups showed a significant effect for time on RPE on all three measurements. The analyses showed only an interaction effect between groups on time for the RPE after the squat exercise (p = 0.002).

Conclusion

We conclude that there are no additional benefits of increasing the training frequency from two to four sessions under volume-equated conditions, but it could be favorable to spread the total training volume into several training bouts through the week to avoid potential increases in RPE, especially after the squat exercise.

Effects of Six Weeks of High-Intensity Functional Training on Physical Performance in Participants with Different Training Volumes and Frequencies

High-intensity functional training (HIFT) is characterized by presenting high volumes and training intensities with constantly varied exercises. The aim of this study was to analyze the internal training load and the effects of high-intensity functional training on physical performance in subjects with different training volumes and frequencies. A total of 31 volunteers involved in high-intensity functional training (14 men and 17 women) were divided according to their training volumes and frequencies (high training-volume and frequency-HTVF; (n = 17) (nine women and eight men; age: 31.0 ± 6.3 years; height: 168.8 ± 8.1 cm, body weight: 73.6 ± 11.9 kg; BMI: 25.96 kg/m²) and moderate training volume and frequency-MTVF; (n = 14) (eight women and six men; age: 26.6 ± 4.7 years; height: 167.2 ± 8.6 cm, body weight: 75.8 ± 18.0 kg; BMI: 27.33 kg/m²)). The internal training load was determined using the session-rating of perceived exertion method. The monotony index (MI) and training strain (TS) were used to determine training variability during the training weeks. Countermovement vertical jump height, 20-m sprinting and handgrip strength were assessed at baseline and after six weeks of training. There was a time effect for MI ((F_{(5, 145)} = 5.942; p = 0.0001)), TS ((F_{(5, 145)} = 5.734; p = 0.0001)), weekly internal training load ((F_{(4.006, 116.87)} = 4.188; p = 0.003)) and mean weekly internal training load ((F_{(4.006, 116.87)} = 4.188; p = 0.003)). There was no increase in performance in either group for countermovement vertical jump height ((F_(1,29) = 6.081; p = 0.050)), sprinting ((F_(1,29) = 1.014; p = 0.322)), right handgrip strength ((F_(1,29) = 2.522; p = 0.123)) or left handgrip strength ((F_(1,29) = 2.550; p = 0.121)). The current findings suggest that six weeks of high-intensity functional training was not able to increase performance in either group. Therefore, different volumes and frequencies do not seem to influence the increase in physical performance of HIFT practitioners.

Effects of a resistance training program on muscular performance adaptations: comparing three vs. four times per week

Study aim: The aim of this study was to examine the effects of 8 weeks of resistance training (RT) with three vs. four sessions per week and equated training volume on muscular adaptations in men.

Materials and methods: Thirty-three healthy young men volunteered to participate in the study and were randomly assigned to three times per week whole-body RT (RT3, n = 11), four times per week whole-body RT (RT4, n = 11) or a control group (CG, n = 11). Before and after training, participants were evaluated for one-repetition maximum (1RM) and muscular endurance (i.e., 60% of 1RM to failure) for the leg press and bench press. In addition, thigh, arm, chest, and calf circumferences, and percent body fat were assessed before and after training.

Results: The findings revealed significant main effects of time for chest and thigh circumferences (p ≤ 0.05). There were no significant group × time interactions for chest and thigh circumferences (p > 0.05), but the RT4 showed greater changes (effect size [ES]: 0.48 vs. 0.15) in chest circumference, while the RT3 showed greater changes (ES: 0.77 vs. 0.35) in thigh circumference. Significant group × time interactions were observed for the 1RM of leg and bench presses (p < 0.05). Post-hoc analyses showed greater improvements for RT3 in comparison to RT4 in 1RM bench press (p = 0.01, ES: 0.77 vs. 0.6) and leg presses (p = 0.009, ES: 0.94 vs. 0.86).

Conclusions: These results suggest that RT induces meaningful adaptive effects to improve strength and muscle size in men and RT3 appears to be more effective to induce muscular adaptations.

Importance of Frequency and Intensity of Strength Training for Reduced Musculoskeletal Pain in the Back, Neck-Shoulder, and Arm-Hand Among Physical Therapists

BACKGROUND

Musculoskeletal pain (MP) is common among health care professionals, including physical therapists (PTs). The physically demanding nature of their work might contribute to increase MP rates. Strength training has a positive effect on musculoskeletal health and MP. However, no studies have evaluated the association of strength training during leisure time on MP among PTs. This study aims to analyze the association between frequency and intensity of strength training during leisure time and MP in the back, neck-shoulder, and arm-hand among PTs.

METHODS

Data on MP and intensity and frequency of strength training were obtained using a questionnaire responded by 1006 PTs. The odds for having lower level of MP as a function of intensity or frequency of the strength training were estimated using binary logistic regression.

RESULTS

High-intensity strength training showed strong associations with lower intensity of MP in neck-shoulder (odds ratio = 5.08; 95% confidence interval, 1.36-18.92), arm-hand (odds ratio = 5.22; 95% confidence interval, 1.11-24.51), and back (odds ratio = 5.22; 95% confidence interval, 1.41-19.28). However, frequency and lower intensities were not significantly associated with MP in any body part.

CONCLUSIONS

High-intensity strength training is strongly associated with lower levels of MP in arm-hand, neck-shoulder, and back, whereas no association was found with frequency or lower intensities.

Similar Muscular Adaptations in Resistance Training Performed Two Versus Three Days Per Week

The purpose of the present study was to compare changes in muscle strength and hypertrophy between volume-equated resistance training (RT) performed 2 versus 3 times per week in trained men. Thirty-six resistance-trained men were randomly assigned to one of the two experimental groups: a split-body training routine (SPLIT) with muscle groups trained twice per week (n = 18) over four weekly sessions, or a total-body routine (TOTAL), with muscle groups being trained three times per week (n = 18) over three weekly sessions. The training intervention lasted 10 weeks. Testing was carried out pre- and post-study to assess maximal muscular strength in the back squat and bench press, and hypertrophic adaptations were assessed by measuring muscle thickness of the elbow flexors, elbow extensors, and quadriceps femoris. Twenty-eight subjects completed the study. Significant pre-to-post intervention increases in upper and lower-body muscular strength occurred in both groups with no significant between-group differences. Furthermore, significant pre-to-post intervention increases in muscle size of the elbow extensors and quadriceps femoris occurred in both groups with no significant between-group differences. No significant pre-to-post changes were observed for the muscle size of elbow flexors both in the SPLIT or TOTAL group. In conclusion, a training frequency of 2 versus 3 days per week produces similar increases in muscular adaptations in trained men over a 10-week training period. Nonetheless, effect size differences favored SPLIT for all hypertrophy measures, indicating a potential benefit for training two versus three days a week when the goal is to maximize gains in muscle mass.

Resistance-exercise training ameliorates LPS-induced cognitive impairment concurrent with molecular signaling changes in the rat dentate gyrus

Effective treatments preventing brain neuroinflammatory diseases are lacking. Resistance-exercise training (RT) ameliorates mild cognitive impairment (MCI), a forerunner to neuroinflammatory diseases. However, few studies have addressed the molecular basis by which RT abates MCI. Thus experiments were performed to identify some molecular changes occurring in response to RT in young, female Wistar rats. To induce MCI, intraventricular lipopolysaccharide (LPS) injections were used to increase dentate gyrus inflammation, reflected by significantly increased TNF-α (~400%) and IL-1β (~1,500%) mRNA (P < 0.0001) after 6 wk. Five days after LPS injections, half of LPS-injected rats performed RT by ladder climbing for 6 wk, 3 days/wk, whereas half remained without ladders. RT for 6 wk increased lean body mass percentage (P < 0.05), individual muscle masses (gastrocnemius and tibialis anterior) (P < 0.05), and maximum lifting capacity (P < 0.001). The RT group, compared with sedentary controls, had 1) ameliorated spatial learning deficits (P < 0.05), 2) increased dentate gyrus phosphorylation of IGF-1R, protein kinase B, and GSK-3β proteins (P < 0.05), components of downstream IGF-1 signaling, and 3) increased dentate gyrus synaptic plasticity marker synapsin protein (P < 0.05). Two follow-up experiments (without LPS) characterized dentate gyrus signaling during short-term RT. Twenty-four hours following the third workout in a 1-wk training duration, phosphorylation of ERK1/2 and GSK-3β proteins, as well as proliferation marker protein, PCNA, were significantly increased (P < 0.05). Similar changes did not occur in a separate group of rats following a single RT workout. Taken together, these data indicate that RT ameliorates LPS-induced MCI after RT, possibly mediated by increased IGF-1 signaling pathway components within the dentate gyrus. NEW & NOTEWORTHY The data suggest that resistance-exercise training restores cognitive deficits induced by lipopolysaccharides and can activate associated IGF-1 signaling in the dentate gyrus. Our data show, for the first time, that as few as three resistance-exercise workouts (spread over 1 wk) can activate IGF-1 downstream signaling and increase proliferation marker PCNA in the dentate gyrus.

How many times per week should a muscle be trained to maximize muscle hypertrophy? A systematic review and meta-analysis of studies examining the effects of resistance training frequency

Training frequency is considered an important variable in the hypertrophic response to regimented resistance exercise. The purpose of this paper was to conduct a systematic review and meta-analysis of experimental studies designed to investigate the effects of weekly training frequency on hypertrophic adaptations. Following a systematic search of PubMed/MEDLINE, Scoups, and SPORTDiscus databases, a total of 25 studies were deemed to meet inclusion criteria. Results showed no significant difference between higher and lower frequency on a volume-equated basis. Moreover, no significant differences were seen between frequencies of training across all categories when taking into account direct measures of growth, in those considered resistance-trained, and when segmenting into training for the upper body and lower body. Meta-regression analysis of non-volume-equated studies showed a significant effect favoring higher frequencies, although the overall difference in magnitude of effect between frequencies of 1 and 3+ days per week was modest. In conclusion, there is strong evidence that resistance training frequency does not significantly or meaningfully impact muscle hypertrophy when volume is equated. Thus, for a given training volume, individuals can choose a weekly frequency per muscle groups based on personal preference.