Effects of periodic and continued resistance training on muscle CSA and strength in previously untrained men

Does Taking a Break Matter-Adaptations in Muscle Strength and Size Between Continuous and Periodic Resistance Training

We aimed to compare the effects of periodic resistance training (RT) and continuous RT on muscle strength and size. Fifty-five healthy, untrained participants (age 32 ± 5 years) were randomized to periodic (PRT, n = 20 completed the study, 45% females) or continuous (CRT, n = 22 completed the study, 45% females) groups. PRT completed a 10-week RT, a 10-week detraining, and a second identical 10-week RT. CRT began with a 10-week non-RT, followed by a 20-week RT. RT included twice-weekly supervised whole-body RT sessions. Leg press (LP) and biceps curl (BC) one repetition maximum (1RM), countermovement jump (CMJ) height, muscle cross-sectional area (CSA) of vastus lateralis (VL), and biceps brachii (BB) using ultrasound imaging were measured twice at the beginning and every fifth week during the intervention. Both groups increased (p < 0.001) 1RM in LP and BC, CSA in VL and BB, and CMJ height with no differences between the groups. In PRT, 1RM in LP and BC, CSA in VL and BB, and CMJ height decreased during detraining (p < 0.05). During the first 5 weeks of retraining in PRT, increases in LP 1RM, and VL and BB CSA were greater than in CRT during Weeks 10-15 of their CRT (p < 0.01). PRT and CTR ended up in similar postintervention adaptations, as decreased muscle strength and size during detraining in PRT regained rapidly during retraining. Our results therefore suggest that trainees should not be too concerned about occasional short-term training breaks in their daily lives when it comes to lifelong strength training. Trial Registration: ClinicalTrials.gov identifier: NCT05553769.

Gaining more from doing less? The effects of a one-week deload period during supervised resistance training on muscular adaptations

Background

Based on emerging evidence that brief periods of cessation from resistance training (RT) may re-sensitize muscle to anabolic stimuli, we aimed to investigate the effects of a 1-week deload interval at the midpoint of a 9-week RT program on muscular adaptations in resistance-trained individuals.

Methods

Thirty-nine young men (n = 29) and women (n = 10) were randomly assigned to 1 of 2 experimental, parallel groups: An experimental group that abstained from RT for 1 week at the midpoint of a 9-week, high-volume RT program (DELOAD) or a traditional training group that performed the same RT program continuously over the study period (TRAD). The lower body routines were directly supervised by the research staff while upper body training was carried out in an unsupervised fashion. Muscle growth outcomes included assessments of muscle thickness along proximal, mid and distal regions of the middle and lateral quadriceps femoris as well as the mid-region of the triceps surae. Adaptions in lower body isometric and dynamic strength, local muscular endurance of the quadriceps, and lower body muscle power were also assessed.

Results

Results indicated no appreciable differences in increases of lower body muscle size, local endurance, and power between groups. Alternatively, TRAD showed greater improvements in both isometric and dynamic lower body strength compared to DELOAD. Additionally, TRAD showed some slight psychological benefits as assessed by the readiness to train questionnaire over DELOAD.

Conclusion

In conclusion, our findings suggest that a 1-week deload period at the midpoint of a 9-week RT program appears to negatively influence measures of lower body muscle strength but has no effect on lower body hypertrophy, power or local muscular endurance.

Pectoralis major and triceps brachii cross-sectional area measured on different planes: the effect on the muscle size-strength relationship

BACKGROUND

Magnetic resonance imaging (MRI) is a well-used technique to assess muscle size and can be acquired on different planes. Pectoralis major (PM) and triceps brachii (TB) muscles are often acquired and analyzed on the axial plane, however it is unknown if anatomical cross-sectional area (CSA) calculated from different planes will affect the muscle size-strength relationship. Thus, the first aim of the present study was to identify if the CSA of the PM and TB measured on different planes presents a similar muscle size-strength relationship. A secondary aim was to investigate if the quantification of CSA of the PM and TB muscles are similar between sagittal and axial plane.

METHODS

Fifteen males underwent an MRI examination, and after that, one-repetition maximum (1RM) test was performed.

RESULTS

There was a significant relationship between 1RM and PM CSA measured on the axial and sagittal plane (r≤0.81), while the relationship with TB CSA was only good on the axial plane (r=0.65) and not significant on the sagittal plane (r=0.27). ICC between planes was excellent for PM CSA (0.96) with Bland-Altman procedure showing agreement between planes (d=0.376; P=0.612). Contrarily, TB CSA ICC was week (0.07), with Bland-Altman procedure showing no agreement between planes (d=-24.49; P=0.022).

CONCLUSIONS

CSA measured at axial plane from PM and TB muscles showed a significant relationship with 1RM, while only PM CSA on the sagittal plane showed a significant relationship with 1RM. Finally, it was demonstrated that PM images showed a great reliability between planes, which was not true for TB muscle.

A Chair-Based Music-Kinetic Combined Exercise Program as an Alternative Approach for Increasing Health, Functional Capacity, and Physical Fitness Indices in Middle-Aged Pre-Menopausal Women

Lately, chairs have been widely used as a cheap, easily accessible, safe, and effective training means in different settings (e.g., in gyms, the house, workplaces, and in rehabilitation). This study investigated the effectiveness of a 10-week chair-based music-kinetic integrated combined exercise program on health, functional capacity, and physical fitness indicators of middle-aged pre-menopausal women. A total of 40 healthy women (40-53 years) were assigned to two groups: exercise (EG) and control (CG). The EG followed a 10-week (3 times/weekly; 30 training sessions) chair-based exercise program including aerobic dance, flexibility, coordination, and strength exercises with body weight or auxiliary means. Selected indicators of health, functional capacity, and physical fitness were evaluated before and after the 10 weeks. Following the program, the EG significantly reduced their body fat (-2.5%), blood pressure (by -4.5 to -5.5%), the time during the timed up-and-go (TUG) test (by -10.27%), heart rate (by -6.35 to -13.78%), and the rate of perceived exertion (by -24.45 to -25.88%), while increasing respiratory function (3.5-4%), flexibility (12.17%), balance (50.38-51.07%), maximal handgrip strength (10-12.17%), and endurance strength (43.87-55.91%). The chair-based combined music-kinetic exercise program was effective and could be safely used in different settings to improve health, functional capacity, and physical fitness in middle-aged women.

The effects of resistance training to near failure on strength, hypertrophy, and motor unit adaptations in previously trained adults

Limited research exists examining how resistance training to failure affects applied outcomes and single motor unit characteristics in previously trained individuals. Herein, resistance-trained adults (24 ± 3 years old, self-reported resistance training experience was 6 ± 4 years, 11 men and 8 women) were randomly assigned to either a low-repetitions-in-reserve (RIR; i.e., training near failure, n = 10) or high-RIR (i.e., not training near failure, n = 9) group. All participants implemented progressive overload during 5 weeks where low-RIR performed squat, bench press, and deadlift twice weekly and were instructed to end each training set with 0-1 RIR. high-RIR performed identical training except for being instructed to maintain 4-6 RIR after each set. During week 6, participants performed a reduced volume-load. The following were assessed prior to and following the intervention: (i) vastus lateralis (VL) muscle cross-sectional area (mCSA) at multiple sites; (ii) squat, bench press, and deadlift one-repetition maximums (1RMs); and (iii) maximal isometric knee extensor torque and VL motor unit firing rates during an 80% maximal voluntary contraction. Although RIR was lower in the low- versus high-RIR group during the intervention (p < 0.001), total training volume did not significantly differ between groups (p = 0.222). There were main effects of time for squat, bench press, and deadlift 1RMs (all p-values < 0.05), but no significant condition × time interactions existed for these or proximal/middle/distal VL mCSA data. There were significant interactions for the slope and y-intercept of the motor unit mean firing rate versus recruitment threshold relationship. Post hoc analyses indicated low-RIR group slope values decreased and y-intercept values increased after training suggesting low-RIR training increased lower-threshold motor unit firing rates. This study provides insight into how resistance training in proximity to failure affects strength, hypertrophy, and single motor unit characteristics, and may inform those who aim to program for resistance-trained individuals.

"You can't shoot another bullet until you've reloaded the gun": Coaches' perceptions, practices and experiences of deloading in strength and physique sports

Deloading refers to a purposeful reduction in training demand with the intention of enhancing preparedness for successive training cycles. Whilst deloading is a common training practice in strength and physique sports, little is known about how the necessary reduction in training demand should be accomplished. Therefore, the purpose of this research was to determine current deloading practices in competitive strength and physique sports. Eighteen strength and physique coaches from a range of sports (weightlifting, powerlifting, and bodybuilding) participated in semi-structured interviews to discuss their experiences of deloading. The mean duration of coaching experience at ≥ national standard was 10.9 (SD = 3.9) years. Qualitative content analysis identified Three categories: definitions, rationale, and application. Participants conceptualised deloading as a periodic, intentional cycle of reduced training demand designed to facilitate fatigue management, improve recovery, and assist in overall training progression and readiness. There was no single method of deloading; instead, a reduction in training volume (achieved through a reduction in repetitions per set and number of sets per training session) and intensity of effort (increased proximity to failure and/or reduction in relative load) were the most adapted training variables, along with alterations in exercise selection and configuration. Deloading was typically prescribed for a duration of 5 to 7 days and programmed every 4 to 6 weeks, although periodicity was highly variable. Additional findings highlight the underrepresentation of deloading in the published literature, including a lack of a clear operational definition.

Intelligent Physical Exercise Training (IPET) in the offshore wind industry: a feasibility study with an adjusted conceptual model

Background

Good physical health and capacity is a requirement for offshore wind service technicians (WTs) who have substantial physical work demands and are exposed to numerous health hazards. Workplace physical exercise has shown promise for improving physical health and work ability among various occupational groups. Therefore, we aimed to assess the feasibility and preliminary efficacy of Intelligent Physical Exercise Training (IPET) among WTs in the offshore wind industry.

Methods

A within-subject design was used to assess the feasibility and preliminary efficacy of IPET (one hour/week individualized exercise during working hours). The intervention period was 12 weeks, with the first eight weeks performed on site as supervised or partly supervised exercise during work hours and the last four weeks planned as home-administered exercise after the seasonal offshore service period. Three assessments, T1 (six months prior to intervention start), T2 (start of intervention) and T3 (end of intervention), of physical health and capacity (self-reported and objective measurements) were conducted and the period between T1 and T2 served as a within-subject control period. Primary outcome was feasibility measured as compliance, adherence, adverse events, and participant acceptability. Descriptive statistics were used to present feasibility outcomes. Preliminary efficacy was reported as mean differences with 95% confidence intervals for health and physical capacity outcomes between T1 and T2, between T2 and T3 and between T1 and T3.

Results

All WTs at the included wind farm (n=24, age: 40 years (SD±8)) participated in the study. No serious adverse events were reported. Compliance and adherence of 95 and 80% respectively, were reached in the eight-week supervised part, but were lower when exercise was home-administered (<20%). Acceptability was high for the supervised part, with 83% indicating that the exercise program worked well and 100% that exercise should be implemented as an integrated part of the working structure. Changes in physical capacity and health indicators, such as VO2max (ml O2/kg/min) at T1 (38.6 (SD±7.2)), T2 (44.1 (SD±9)) and T3 (45.8 (SD±6.5)), may indicate seasonal fluctuations as well as improvements from the intervention.

Conclusion

On-site Intelligent Physical Exercise Training during working hours was feasible and well received among WTs in the offshore wind industry. The proceeding of larger-scale evaluation and implementation is therefore recommended.

Trial registration

ClinicalTrials.gov (Identifier: NCT04995718). Retrospectively registered on August 6, 2021,

Serial vs. Integrated Outdoor Combined Training Programs for Health Promotion in Middle-Aged Males

The purpose of this study was to examine and compare the training and detraining effects of outdoor serial and integrated combined exercise programs on health, functional capacity, and physical fitness indices. Fifty-one untrained overweight/obese males (47 ± 4 years) were divided into a serial combined (SCG), an integrated combined (ICG), or a control (CG) group. The SCG and ICG implemented a 3-month training (3 sessions/week) consisting of walking and body weight exercises. The only difference between SCG and ICG was the sequence of aerobic and strength training. In SCG, the strength training was performed before aerobic training, while in ICG the aerobic and the strength training were alternated repeatedly in a predetermined order. Health, functional capacity, and physical fitness indices were measured before the training, following the termination of programs, and 1-month after training cessation. Following the training, both the SCG and ICG groups showed reduced blood pressure, heart rate, body fat, and waist-to-hip ratio (3−11%; p < 0.001), with improved respiratory function, muscle strength, aerobic capacity, flexibility, and balance (14−61%; p < 0.001). After 1-month of training cessation, significant reductions (p < 0.05) were observed in health indices and physical fitness without returning to baseline levels. However, there were no differences between SCG and ICG after training and training cessation (p > 0.05). In CG, all the above variables did not change. Furthermore, a great percentage of participants in both exercise groups (90%) reported high levels of enjoyment. In conclusion, both serial and integrated outdoor combined walking and body weight strength training programs are enjoyable and equally effective for improving health, functional capacity, and physical fitness indices in overweight/obese middle-aged males.

Pectoralis Cross-Sectional Area can be Accurately Measured using Panoramic Ultrasound: A Validity and Repeatability Study

The objective of the current study was to examine the validity and repeatability of panoramic ultrasound in evaluating the anatomical cross-sectional area (ACSA) of the pectoralis major. Specifically, we aimed to quantify the measurement errors generated during the image acquisition and analysis (repeatability), as well as when comparing with magnetic resonance imaging (MRI) (validity). Moreover, we aimed to analyze the influence of the operator's experience on these measurement errors. Both sides of the chest of 16 participants (n = 32) were included. Errors made by two operators (trained and novice) when measuring pectoralis major ACSA (50% of sternum-areola mammae distance) were examined. Acquisition errors included the comparison of two images acquired 5 min apart. Acquisition 1 was analyzed twice to quantify analysis errors. Thereafter, acquisition 1 was compared with MRI. Statistics include the standard error of measurement (SEM), expressed in absolute (cm²) and relative (%) terms as a coefficient of variation (CV), and the calculation of systematic bias. Errors made by the trained operator were lower than those made by the novice, especially during the image acquisition (SEM = 0.25 vs. 0.66 cm², CV = 1.06 vs. 2.98%) and when compared with MRI (SEM = 0.27 vs. 1.90 cm², CV = 1.13 vs. 8.16%). Furthermore, although both operators underestimated the ACSA, magnitude and variability [SD] of these errors were lower for the trained operator (bias = -0.19 [0.34] cm²) than for the novice (bias = -1.97 [2.59] cm²). Panoramic ultrasound is a valid and repeatable technique for measuring pectoralis major ACSA, especially when implemented by a trained operator.

Muscle volume vs. anatomical cross-sectional area: Different muscle assessment does not affect the muscle size-strength relationship

Muscle volume (MV) and anatomical cross-sectional area (CSA) are used as measures of muscle-size, but determining these from magnetic resonance imaging (MRI) is a very time-consuming process. Additionally, it is unclear if the use of different muscle size assessments (all vs. reduced number of slices images) would impact the muscle size-strength relationship. Thus, this study aimed to investigate if muscle size calculation by using a reduced or all slices images from pectoralis major (PM) would maintain a similar muscle size-strength relationship with bilateral maximal dynamic and isometric contractions on a bench press exercise. Twenty-four healthy males underwent an MRI examination to measure PM muscle size, and maximal isometric and dynamic contractions (by one repetition maximum, 1RM) were performed. Correlations between maximal isometric voluntary force (MVF) and dynamic strength (1RM) with muscle size variables [three images from the largest part of PM (CSA_3MAX), three images accounting for the shape -first image, middle image, final image- of the PM (CSA₃), and MV] were performed. The correlation between 1RM with MV, CSA₃, and CSA_3MAX were 0.84, 0.832, and 0.727 (p < 0.001), respectively. The correlation between MVF with MV, CSA₃, and CSA_3MAX were 0.738, 0.733, and 0.604 (p < 0.001), respectively. Overall, PM MV and CSA₃ exhibit a stronger and similar muscle size-strength relationship during maximal dynamic and isometric tests than CSA_3MAX. Therefore, a reduced number of slices (CSA₃) could be used as an alternative to considerably reduce the time of analysis without compromise muscle size-strength relationship.

Maslinic Acid Promotes Hypertrophy Induced by Functional Overload in Mouse Skeletal Muscle

Nutritional supplements are sometimes important for athletes to improve their sports performance and maintain their condition. Maslinic acid (MA) is a type of compound with a pentacyclic triterpene structure extracted from olives, and has a strong anti-inflammatory effect and improves metabolic function. This study aimed to investigate the effects of MA on muscle hypertrophy by functional overload using an animal model. Mice plantaris muscles were overloaded by synergist ablation surgery with/without MA and they were sampled at 4, 7, and 14 d after the operation. We demonstrated that MA significantly increased plantaris' cross-sectional area and activated the mechanistic target of rapamycin (mTOR) signaling compared with the non-supplemented group (main effect of MA, p<0.05). In addition, MA also significantly reduced catabolic proteins compared with the non-supplemented group. MA supplementation increased muscle fiber size and promoted muscle hypertrophy via mTOR signaling. Our results indicate that MA supplementation may be useful for promoting hypertrophy of skeletal muscle.

The effect of different resistance training protocols equalized by time under tension on the force-position relationship after 10 weeks of training period

This study investigated the impact of performing two equalized resistance training (RT) protocols for 10 weeks that differ only by repetition duration and number in the force-position and EMG-position relationship. Participants performed an equalized (36 s of time under tension; 3-4 sets; 3 min between sets; 50-55% of one-repetition maximum; 3× week) RT intervention on the bench press and the only different change between protocols was repetition number (RN; 12 vs.6) or duration (RD; 3 s vs. 6 s). Two experimental groups (RN₁₂RD₃, n = 12; and RN₆RD₆, n = 12) performed the RT, while one group was the control (Control, n = 11). Maximal isometric contractions at 10%, 50% and 90% of total bench press range of motion were performed pre- and post-RT, while electromyography was recorded. It demonstrated an increase in isometric force (+14% to 24%, P < 0.001) shifting up the force-position relationship of the training groups after RT, although no difference was between training groups compared to the Control. Neuromuscular activation from pectoralis major presented an increase after training for both RT groups (+44%; P < 0.001) compared to the Control. However, although not significantly different, triceps brachii also presented an increase depending on the protocol (+25%). In conclusion, 10 weeks of an equalized RT with longer RN and shorter RD (or opposite) similarly increases the ability to produce maximal isometric force during the bench exercise across different angles, while neuromuscular activation of the pectoralis major partially explained the shift-up of the force-position relationship after training.

Equalization of Training Protocols by Time Under Tension Determines the Magnitude of Changes in Strength and Muscular Hypertrophy

Martins-Costa, HC, Lacerda, LT, Diniz, RCR, Lima, FV, Andrade, AGP, Peixoto, GH, Gomes, MC, Lanza, MB, Bemben, MG, and Chagas, MH. Equalization of training protocols by time under tension determines the magnitude of changes in strength and muscular hypertrophy. J Strength Cond Res XX(X): 000-000, 2021-The aim of this study was to investigate the effects of 2 training protocols equalized by tension (TUT) on maximal strength (1 repetition maximum [RM]), regional cross-sectional areas (proximal, middle, and distal), and total cross-sectional areas (sum of the regional cross-sectional areas) of the pectoralis major and triceps brachii muscles. Thirty-eight men untrained in resistance training participated in the study and were allocated under 3 conditions: Protocol 3s (n = 11; 12 repetitions; 3s repetition duration), Protocol 6s (n = 11; 6 repetitions; 6s repetition duration), and Control (n = 11; no training). Training protocols (10 weeks; bench press exercise) were equated for TUT (36 seconds per set), number of sets (3-4), intensity (50-55% of 1RM), and rest between sets (3 minutes). Analysis of variance was used to examine a percentage change in variables of interest across the 3 groups with an alpha level of 0.05 used to establish statistical significance. Protocols 3s and 6s showed no differences in the increase of total and regional muscle cross-sectional areas. There were no differences in regional hypertrophy of the pectoralis major muscle. In the triceps brachii muscle, the increase in distal cross-sectional area was greater when compared with the middle and proximal regions. Both experimental groups had similar increases in the 1RM test. In conclusion, training protocols with the same TUT promote similar strength gains and muscle hypertrophy. Moreover, considering that the protocols used different numbers of repetitions, the results indicate that training volumes cannot be considered separately from TUT when evaluating neuromuscular adaptations.

Effect of endurance exercise duration on muscle hypertrophy induced by functional overload

For many ball games, both resistance and endurance training are necessary to improve muscle strength and endurance capacity. Endurance training has been reported to inhibit muscle strength and hypertrophy, but some studies have reported that endurance exercise (EE) does not inhibit the effects of resistance exercise. Here, we examined the effect of short‐ or long‐duration EE on mouse skeletal muscle hypertrophy induced by functional overload (OL) at the molecular level. Plantaris muscle hypertrophy was induced by OL with synergist ablation in mice. Body mass was reduced with endurance training, but EE duration (30 or 90 min) had no effect. The ratio of plantaris muscle weight to body weight was higher in the OL and EE for 30 min (OL+EE30) and OL and EE for 90 min (OL+EE90) groups compared with the OL group. Expression of mechanistic target of rapamycin signaling proteins, which is related to protein synthesis and hypertrophy, was increased in the OL+EE30 group. Expression of Forkhead box‐containing protein O1, which is related to protein breakdown and atrophy, remained unchanged. However, microtubule‐associated protein 1 light chain 3, a known marker of autophagy, and MAFbx, which is related to protein breakdown, were significantly increased in the OL+EE90 group. Furthermore, markers of oxidative stress, ubiquitin and 4‐hydroxynonenal were also significantly increased in the OL+EE90 group compared with other groups. In conclusion, EE duration did not affect body mass and plantaris mass and did not interfere with mechanistic target of rapamycin signaling, but it did increase ubiquitinated proteins and oxidative stress. It is therefore necessary to consider training durations for EE when combining endurance and resistance training.

Global Challenges of Being a Strength Athlete during a Pandemic: Impacts and Sports-Specific Training Considerations and Recommendations

The ongoing global pandemic brought about by Coronavirus II (SARS-Cov-2 or COVID-19) has caused an ongoing cessation of sporting competitions and training facility closures. This is a fundamental challenge for amateur and elite sporting professionals. Although recommendations have been provided for team-sport athletes to maintain general and sport-specific conditioning, these methods are often not optimal for strength athletes (i.e., powerlifting (PL) and weightlifting (WL)) due to the unique and narrow set of performance requirements posed by these sports. The purpose of this review is to provide evidence-based information and recommendations and highlight potential strategies and approaches that may be used by strength (PL and WL) athletes during the current global crisis. Collectively, we provide evidence from resistance training literature regarding the loss of muscle strength, power and mass, minimum training frequencies required to attenuate such losses and training re-adaptation. Additionally, we suggest that time off training and competition caused by ongoing restrictions may be used for other purposes, such as overcoming injury and improving movement quality and/or mobility, goal setting, psychological development and emphasizing strength sports for health. These suggestions are intended to be useful for coaches, strength athletes and organizations where existing training strategies and recommendations are not suitable or no longer feasible.

The order of concurrent training affects mTOR signaling but not mitochondrial biogenesis in mouse skeletal muscle

Concurrent training involves a combination of two different modes of training. In this study, we conducted an experiment by combining resistance and endurance training. The purpose of this study was to investigate the influence of the order of concurrent training on signal molecules in skeletal muscle. The phosphorylation levels of p70 S6 kinase, S6 ribosomal protein, and 4E-binding protein 1, which are related to hypertrophy signaling, increased significantly in the resistance-endurance order group as compared with in control group not the endurance-resistance order group. The gene expressions related to metabolism were not changed by the order of concurrent training. The mitochondrial respiratory chain complex was evaluated by western blot. Although both groups of concurrent training showed a significant increase in MTCO1, UQCRC2, and ATP5A protein levels, we could not detect a difference based on the order of concurrent training. In conclusion, a concurrent training approach involving resistance training before endurance training on the same day is an effective way to activate both mTOR signaling and mitochondria biogenesis.

Training, detraining, and retraining: Two 12-week respiratory muscle training regimens in a child with infantile-onset Pompe disease

BACKGROUND

Respiratory muscle weakness is a primary cause of morbidity and mortality in patients with Pompe disease. We previously described the effects of our 12-week respiratory muscle training (RMT) regimen in 8 adults with late-onset Pompe disease [1] and 2 children with infantile-onset Pompe disease [2].

CASE REPORT

Here we describe repeat enrollment by one of the pediatric participants who completed a second 12-week RMT regimen after 7 months of detraining. We investigated the effects of two 12-week RMT regimens (RMT #1, RMT #2) using a single-participant A-B-A experimental design. Primary outcome measures were maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP). Effect sizes for changes in MIP and MEP were determined using Cohen's d statistic. Exploratory outcomes targeted motor function.

RELEVANCE

From pretest to posttest, RMT #2 was associated with a 25% increase in MIP and a 22% increase in MEP, corresponding with very large effect sizes (d= 2.92 and d= 2.65, respectively). Following two 12-week RMT regimens over 16 months, MIP increased by 69% and MEP increased by 97%, corresponding with very large effect sizes (d= 3.57 and d= 5.10, respectively). MIP and MEP were largely stable over 7 months of detraining between regimens. Magnitude of change was greater for RMT #1 relative to RMT #2.

El efecto de los programas de fuerza muscular sobre la capacidad funcional. Revisión sistemática

Introducción. El número de estudios relacionados con la fuerza muscular y la funcionalidad invitan al análisis en profundidad de sus resultados antes de su aplicación profesional.Objetivo. Desarrollar una revisión sistemática para la construcción de programas de actividad física centrados en el entrenamiento de fuerza muscular y la capacidad funcional de sedentarios entre los 19 y 79 años.Materiales y métodos. Se emplearon los parámetros PRISMA, Chocrane y de la Universidad de York para el diseño y ejecución de revisiones sistemáticas. Además, se garantizaron criterios de calidad y especificidad estrictos que permitieron identificar 14 categorías de análisis, de las cuales emergieron las pautas de programación que se informan en la revisión sistemática.Resultados. 49 estudios con nivel de evidencia 1+ (24%), 1- (33%), 2++ (4%), 2+ (29%) y 2- (10%) cumplieron con los criterios de selección establecidos y permitieron alimentar las 14 categorías propuestas y hacer una síntesis de contenido.Conclusión. Es posible elevar el efecto de los programas de actividad física sobre la fuerza muscular y la funcionalidad a partir de la identificación y consideración de unas variables de programación (categoría) básicas que se sustentan en la calidad de evidencia científica circulante.

Resistance Training-Induced Elevations in Muscular Strength in Trained Men Are Maintained After 2 Weeks of Detraining and Not Differentially Affected by Whey Protein Supplementation

Hwang, PS, Andre, TL, McKinley-Barnard, SK, Morales Marroquín, FE, Gann, JJ, Song, JJ, and Willoughby, DS. Resistance training-induced elevations in muscular strength in trained men are maintained after 2 weeks of detraining and not differentially affected by whey protein supplementation. J Strength Cond Res 31(4): 869-881, 2017-Resistance training (RT) with nutritional strategies incorporating whey protein intake postexercise can stimulate muscle protein synthesis and elicit hypertrophy. The early phases of training-induced anabolic responses can be attenuated with longer-term training. It is currently unknown if short-term detraining (DT) can restore these blunted anabolic responses during a subsequent retraining (ReT) period. Twenty resistance-trained men (age 20.95 ± 1.23 years; n = 20) were randomized into one of 2 groups (PRO or CHO; 25 g) in a double-blind manner. Participants followed a 4-day per week RT program (4-week RT; 2-week DT; 4-week ReT) while consuming their respective supplement only on workout days during RT and ReT, but every day during DT. At baseline, 4 weeks after RT (post-RT), 2 weeks after DT (post-2-week DT), and after 4 weeks of ReT after DT (post-ReT), leg press strength (LPS) was assessed and rectus femoris cross-sectional area and lean mass changes were assessed by ultrasonography and dual-energy x-ray absorptiometry, respectively. A factorial 2 × 4 (group by time) analyses of variance with repeated measures were used with a probability level at ≤0.05. LPS was elevated throughout the 10-week training study (p = 0.003) with no decrease in LPS after DT in both groups. Although not statistically significant, both groups retained lean mass after DT. A 2-week period of DT appeared to retain muscular strength in resistance-trained men. Therefore, a short-term period of DT can potentially retain lower-body strength in young resistance-trained men irrespective of supplementing with 25 g of whey protein postexercise.

EFFECTS OF PERIODIC AND CONTINUOUS RESISTANCE TRAINING ON MUSCLE STRENGTH IN DETRAINED WOMEN

It has been reported that periodic resistance training (retraining after short-term detraining) could maintain muscle performance. However, the training volume used in previous studies differed between continuous and periodic training groups. This study compared strength gains following 20 sessions of continuous and periodic resistance training programs. 60 healthy, detrained women were randomly assigned into one of two groups: (1) continuous resistance training group or (2) retraining resistance group. The continuous resistance training group performed a non-interrupted resistance training program for 10 wk., while the retraining resistance group trained for 5 wk., detrained 2 wk., and resumed training for 5 wk. All participants performed three sets of 8-12 maximum repetitions of lower- and upper-body exercises two days per week, with at least 48 hr. between sessions. There was no significant difference on knee extensors and elbow flexors peak torque gain between the continuous resistance training group and the retraining resistance group. The results suggest that 2 wk. of detraining does not affect strength gains after a total of 10 wk. in detrained women.

Muscle performance, size, and safety responses after eight weeks of resistance training and protein supplementation: a randomized, double-blinded, placebo-controlled clinical trial

The purpose of this study was to examine the effects of 2 different types of protein supplementation on thigh muscle cross-sectional area (CSA), blood markers, muscular strength, endurance, and body composition after 8 weeks of low- or moderate-volume resistance training in healthy, recreationally trained, college-aged men. One hundred and six men were randomized into 5 groups: low-volume resistance training with bioenhanced whey protein (BWPLV; n = 22), moderate-volume resistance training with BWP (BWPMV; n = 20), moderate-volume resistance training with standard whey protein (SWPMV; n = 22), moderate-volume resistance training with a placebo (PLA; n = 21), or moderate-volume resistance training with no supplementation (CON; n = 21). Except for CON, all groups consumed 1 shake before and after each exercise session and one each on the nontraining day. The BWPLV, BWPMV, and SWPMV groups received approximately 20 g of whey protein per shake, whereas the BWP groups received 5 g of additional polyethylene glycosylated (PEG) leucine. Resistance training sessions were performed 3 times per week for 8 weeks. There were no interactions (p > 0.05) for muscle strength and endurance variables, body composition, muscle CSA, and safety blood markers, but the main effects for training were observed (p ≤ 0.05). However, the Albumin:Globulin ratio for SWPMV was lower (p = 0.037) than BWPLV and BWPMV. Relative protein intake (PROREL) indicated a significant interaction (p < 0.001) with no differences across groups at pre; however, BWPLV, BWPMV, and SWPMV had a greater intake than did PLA or CON at post (p < 0.001). This study indicated that 8 weeks of resistance training improved muscle performance and size similarly among groups regardless of supplementation.

Concomitant changes in cross-sectional area and water content in skeletal muscle after resistance exercise

This study investigated how one bout (1EX) and three bouts (3EX) of strenuous resistance exercise affected the cross-sectional area (CSA) and water content (WC) of the quadriceps muscle and patella tendon (PT), 4 h and 52 h after the last exercise bout. Ten healthy untrained male subjects performed 1EX with one leg and 3EX with the other leg. CSA and WC were measured with magnetic resonance imaging 10, 20 and 30 cm proximal to the tibia plateau (TP) for the muscle, and at the proximal, central and distal site for the PT prior to exercise, and 4 h and 52 h after the last exercise bout. Ten centimeter above the TP, muscle CSA was significantly increased at 4 h (1EX: 13 ± 5%; 3EX: 13 ± 4%) and 52 h (1EX: 16 ± 5%; 3EX: 16 ± 5%) compared with baseline. Muscle WC was significantly increased at 4 h (1EX: 7 ± 1%; 3EX: 6 ± 2%) and 52 h (1EX: 8 ± 2%; 3EX: 8 ± 3%) compared to baseline. PT central CSA was significantly reduced at 52 h (3EX: 14 ± 2%) compared with baseline and (3EX: 13 ± 1%) compared with 4 h. Present data demonstrate that strenuous resistance exercise results in an acute increase in muscle WC and underlines the importance of ensuring sufficient time between the last exercise bout and the determination of anatomical dimensions in muscles.

Time course for arm and chest muscle thickness changes following bench press training

The purpose of this study was to investigate the time course of hypertrophic adaptations in both the upper arm and trunk muscles following high-intensity bench press training. Seven previously untrained young men (aged 25 ± 3 years) performed free-weight bench press training 3 days (Monday, Wednesday and Friday) per week for 24 weeks. Training intensity and volume were set at 75% of one repetition maximum (1-RM) and 30 repetitions (3 sets of 10 repetitions, with 2-3 min of rest between sets), respectively. Muscle thickness (MTH) was measured using B-mode ultrasound at three sites: the biceps and triceps brachii and the pectoralis major. Measurements were taken a week prior to the start of training, before the training session on every Monday and 3 days after the final training session. Pairwise comparisons from baseline revealed that pectoralis major MTH significantly increased after week-1 (p = 0.002), triceps MTH increased after week-5 (p = 0.001) and 1-RM strength increased after week-3 (p = 0.001) while no changes were observed in the biceps MTH from baseline. Significant muscle hypertrophy was observed earlier in the chest compared to that of the triceps. Our results indicate that the time course of the muscle hypertrophic response differs between the upper arm and chest.