Effects of range of motion on muscle development during resistance training interventions: A systematic review

Relationship between histological findings of vastus lateralis muscle and function after total hip arthroplasty in patients with hip fracture: a prospective cohort study

BACKGROUND AND PURPOSE

 We aimed to examine the histological characteristics of vastus lateralis muscles in patients undergoing total hip arthroplasty (THA) following femoral neck fractures and to explore the correlation between muscle fiber types and postoperative functional recovery.

METHODS

 34 patients undergoing THA for femoral neck fractures were included. A biopsy of the vastus lateralis muscle was performed during surgery, followed by immunohistochemical staining. Subsequently, image analysis was conducted to measure the average area of muscle fiber types and the number of type I and II muscle fibers, and the ratio of the area and the number of type II muscle fibers. Functional recovery was assessed 2 weeks post-surgery using the Short Physical Performance Battery (SPPB).

RESULTS

A significant positive correlation was observed between type II muscle fibers and SPPB scores. The ratio of type II muscle fiber area and number strongly correlated with the SPPB scores, indicating a robust static association. The average area of type II fibers showed a strong correlation (r = 0.63, P < 0.001), as did the number of type II fibers (r = 0.53, P = 0.001). Moreover, the ratio of type II muscle fiber area and number significantly correlated with SPPB scores (area: r = 0.77, P < 0.001; number: r = 0.51, P = 0.002), indicating that larger and more numerous type II fibers are associated with better physical performance.

CONCLUSION

The reduction of type II muscle fibers was strongly correlated with a low SPPB postoperative functional recovery in patients who underwent THA following femoral neck fractures.

Comparison of resistance training vs static stretching on flexibility and maximal strength in healthy physically active adults, a randomized controlled trial

BACKGROUND

The aim of the present study was to compare the effects of resistance training through full range of motion and static stretching (SS) of the hip and lower back extensors on flexibility and strength in healthy, physically active, adults.

METHODS

Eighteen participants (age: 24.2 ± 3.0 years, body mass: 71.3 ± 8.9 kg, height: 172.8 ± 7.5 cm) were randomly assigned to either a Resistance Training (RT) (n = 6), SS (n = 6), or control (CON) group (n = 6). The sit & reach (S&R) flexibility test and maximum isometric straight legged deadlift (ISLDL) at 95% and 50% range of motion (ROM) were tested pre- and post-intervention with significance set at p < 0.05. Both groups conducted four to eight sets per session. Within each set, the RT group performed eight repetitions each lasting four seconds, while the SS group stretched continuously for 32 s. The rest periods between each set were 60-90 s. Consequently training volume and rest times were matched between the groups.

RESULTS

The RT and SS groups achieved significant, large magnitude improvements in the S&R test compared to the CON group (p < 0.01 g = 2.53 and p = 0.01, g = 2.44), but no differences were observed between the RT and SS groups (p = 1.00). Furthermore, the RT group demonstrated a larger improvement in 50% and 95% ROM ISLDL compared to SS (p < 0.01, g = 2.69-3.36) and CON (p < 0.01, g = 2.44-2.57).

CONCLUSION

Resistance training through a full ROM was equally effective as SS for improving S&R flexibility, but improved hip- and lower back extensor strength more than SS and the CON. The authors recommend using large ROM resistance training to improve hip and lower back extensor flexibility and muscle strength.

TRIAL REGISTRATION

ISRCTN88839251, registered 24. April 2024, Retrospectively registered.

Kinetic and kinematic profile of eccentric quasi-isometric loading

Eccentric quasi-isometric (EQI) contractions (maintaining a yielding contraction for as long as possible, beyond task failure) have gained interest in research and applied settings. However, little is known regarding the biomechanical profile of EQIs. Fourteen well-trained males performed four maximal effort knee-extensor EQIs, separated by 180 seconds. Angular impulse, velocity, and time-under-tension through the 30-100º range of motion (ROM), and in eight ROM brackets were quantified. Statistical parametric mapping, analyses of variance, and standardised effects (Hedges' g (ES), %Δ) detected between-contraction joint-angle-specific differences in time-normalised and absolute variables. Mean velocity was 1.34º·s-1 with most (62.5 ± 4.9%) of the angular impulse imparted between 40-70º. Most between-contraction changes occurred between 30-50º (p≤ 0.067, ES = 0.53 ± 0.31, 60 ± 52%), while measures remained constant between 50-100º (= 0.069-0.83, ES = 0.10 ± 0.26, 14.3 ± 24.6%). EQIs are a time-efficient means to impart high cumulative mechanical tension, especially at short to medium muscle lengths. However, angular impulse distribution shifts towards medium to long muscle lengths with repeat contractions. Practitioners may utilise EQIs to emphasize the initial portion of the ROM, and limit ROM, or apply EQIs in a fatigued state to emphasize longer muscle lengths.

The Spine is the Tree of Life: A Systematic Review and Meta-Analysis of the Radiographic Findings Related to Spinal Injuries in Athletes

This review article explores spinal injuries in athletes participating in various sporting activities. It also highlights the various mechanisms of injuries that contribute to spinal injuries in each sport. Electronic databases such as PubMed, Cochrane Library, Web of Science, Embase, MEDLINE Ovid, and Google Scholar were searched for articles from 2000 to 2022 on spine injuries in sports and radiological studies discussing the various injury patterns among athletes. Studies were scoured in accordance with the inclusion criteria, and relevant data such as the number of participants, sporting activities, spine injuries, and outcomes were retrieved. Fifteen articles that met the inclusion criteria were included in the study. Cervical spine injuries are common in athletes who participate in contact sports such as football. Similarly, athletes in collision sports such as football, rugby, and hockey are likely to suffer stingers due to traction and compression injuries. Players engaged in such as soccer, baseball, and swimming, are likely to suffer from spondylolysis. Soccer players are more prone to multiple lesions compared to athletes in sports such as baseball because the sport involves training exercises such as jogging and running without kicking any ball. In swimmers, spondylolysis is common in breaststroke and butterfly styles since they involve repeated flexion and hyperextension of the lumbar spine. CT is essential for diagnosing spondylolysis as it demonstrates the lesions more accurately. Ice hockey is associated with a significant incidence of cervical spine injuries, mostly due to players being constantly checked/pushed from behind. Spine injuries are common in elite athletes across several sports. About 10% of spinal injuries in the United States result from sports activities. In diagnosing spine injuries, imaging modalities such as MRI, CT, or plain radiographs are essential. From a radiologist's perspective, these tests help immensely in deciding which treatment is required for a particular athlete or how the injury can be optimally managed. Achieving recovery from a specific spine injury usually depends on the kind of injury and the rehabilitation process the athletes undergo before returning to play.

Effects of blood flow restriction training on sports performance in athletes: a systematic review with meta-analysis

INTRODUCTION

Blood flow restriction training (BFRT) is an effective training method to improve sports performance in healthy athletes. Nevertheless, a systematic review with meta-analysis regarding how BFRT affects sports performance in athletes is still lacking. Consequently, the study attempted to expand and consolidate the prior studies regarding the effect of BFRT on technical and physical performance in athletes.

EVIDENCE ACQUISITION

This study was based on PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyzes) statement guidelines for a systematic review of the academic databases Scopus, Web of Science, PubMed, EBSCOhost (SportDiscus), and Google Scholar. The PEDro scale was used to assess the methodological quality of the included publications, which ranged from moderate to high quality. The systematic review protocol was registered on inplasy.com (INPLASY202380049).

EVIDENCE SYNTHESIS

Out of 249 studies identified, 93 articles were evaluated as eligible, and after the screening, 18 studies were finally included in this systematic review. Meta-analysis results showed a significant enhancement on vertical jump height in the BFRT group compared to the control group (SMD=1.39, 95% CI=0.30-2.49, P=0.01). BFRT was able to significantly increase maximal oxygen uptake (SMD=1.65, 95% CI=0.56-2.74, P<0.01). While no significant improvement in sprint time was observed (SMD= -0.18, 95% CI=-1.18-0.82, P=0.115).

CONCLUSIONS

The finding suggests that BFRT is beneficial to athletes as this training method can be effective in enhancing physical and technical performance in athletes. Nevertheless, further analysis needs to be conducted to fully determine the effectiveness of the moderators of the intervention on sports performance.

Optimizing Resistance Training Technique to Maximize Muscle Hypertrophy: A Narrative Review

Regimented resistance training (RT) has been shown to promote increases in muscle size. When engaging in RT, practitioners often emphasize the importance of appropriate exercise technique, especially when trying to maximize training adaptations (e.g., hypertrophy). This narrative review aims to synthesize existing evidence on what constitutes proper RT exercise technique for maximizing muscle hypertrophy, focusing on variables such as exercise-specific kinematics, contraction type, repetition tempo, and range of motion (ROM). We recommend that when trying to maximize hypertrophy, one should employ a ROM that emphasizes training at long muscle lengths while also employing a repetition tempo between 2 and 8 s. More research is needed to determine whether manipulating the duration of either the eccentric or concentric phase further enhances hypertrophy. Guidelines for body positioning and movement patterns are generally based on implied theory from applied anatomy and biomechanics. However, existing research on the impact of manipulating these aspects of exercise technique and their effect on hypertrophy is limited; it is therefore suggested that universal exercise-specific kinematic guidelines are followed and adopted in accordance with the above recommendations. Future research should investigate the impact of stricter versus more lenient exercise technique variations on hypertrophy.

Preferred Reporting Items for Resistance Exercise Studies (PRIRES): A Checklist Developed Using an Umbrella Review of Systematic Reviews

BACKGROUND

The issues of replication and scientific transparency have been raised in exercise and sports science research. A potential means to address the replication crisis and enhance research reliability is to improve reporting quality and transparency. This study aims to formulate a reporting checklist as a supplement to the existing reporting guidelines, specifically for resistance exercise studies.

METHODS

PubMed (which covers Medline) and Scopus (which covers Medline, EMBASE, Ei Compendex, World Textile Index, Fluidex, Geobase, Biobase, and most journals in Web of Science) were searched for systematic reviews that comprised the primary studies directly comparing different resistance training methods. Basic data on the selected reviews, including on authors, publication years, and objectives, were summarized. The reporting items for the checklist were identified based on the objective of the reviews. Additional items from an existing checklist, namely the Consensus on Exercise Reporting Template, a National Strength and Conditioning Association handbook, and an article from the EQUATOR library were incorporated into the final reporting checklist.

RESULTS

Our database search retrieved 3595 relevant records. After automatic duplicate removal, the titles and abstracts of the remaining 2254 records were screened. The full texts of 137 records were then reviewed, and 88 systematic reviews that met the criteria were included in the umbrella review.

CONCLUSION

Developed primarily by an umbrella review method, this checklist covers the research questions which have been systematically studied and is expected to improve the reporting completeness of future resistance exercise studies. The PRIRES checklist comprises 26 reporting items (39 subitems) that cover four major topics in resistance exercise intervention: 1) exercise selection, performance, and training parameters, 2) training program and progression, 3) exercise setting, and 4) planned vs actual training. The PRIRES checklist was designed specifically for reporting resistance exercise intervention. It is expected to be used with other reporting guidelines such as Consolidated Standards of Reporting Trials and Standard Protocol Items: Recommendations for Interventional Trials. This article presents only the development process and resulting items of the checklist. An accompanying article detailing the rationale for, the importance of, and examples of each item is being prepared.

REGISTRATION

This study is registered with the EQUATOR Network under the title "Preferred Reporting Items for Resistance Exercise Studies (PRIRES)." PROSPERO registration number: CRD42021235259.

Exploring the acute muscle fatigue response in resistance trained individuals during eccentric quasi-isometric elbow flexions-a cross-sectional comparison of repetition and sex

Eccentric quasi-isometrics (EQIs) are a novel, low-velocity resistance exercise technique that incorporates a holding isometric contraction to positional fatigue, followed by voluntary resistance of the resulting eccentric muscle action. As females are typically more fatigue resistant than males during isometric and low-velocity dynamic muscle actions, this study explored sex-differences in the muscle fatigue response to an EQI protocol. Twenty-five (n = 12 female) participants completed 4 unilateral EQI elbow flexions. Absolute and relative surface electromyography (sEMG) amplitude (iEMG, LE peak), mean power frequency (MPF), angular impulse (aIMP), and elbow angle were compared across repetitions and between sexes using discrete values and statistical parametric/non-parametric mapping. There were significant and substantial sex and repetition differences in absolute iEMG, MPF, and aIMP, however, males and females had statistically similar absolute aIMP by repetition 4. When expressed relatively, there were no significant sex-differences. Additionally, there were significant between repetition changes in sEMG amplitude and elbow angle with an increasing number of repetitions, largely in the first-two thirds of repetition time. The current study suggests that there are absolute, but not relative sex-differences in EQI induced muscle fatigue, and the effects across repetitions occur predominately in the first two-thirds of repetition time.

Effect of free-weight vs. machine-based strength training on maximal strength, hypertrophy and jump performance - a systematic review and meta-analysis

BACKGROUND

The effectiveness of strength training with free-weight vs. machine equipment is heavily debated. Thus, the purpose of this meta-analysis was to summarize the data on the effect of free-weight versus machine-based strength training on maximal strength, jump height and hypertrophy.

METHODS

The review was conducted in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, and the systematic search of literature was conducted up to January 1st, 2023. Studies that directly compared free-weight vs. machine-based strength training for a minimum of 6 weeks in adults (18-60 yrs.) were included.

RESULTS

Thirteen studies (outcomes: maximal strength [n = 12], jump performance [n = 5], muscle hypertrophy [n = 5]) with a total sample of 1016 participants (789 men, 219 women) were included. Strength in free-weight tests increased significantly more with free-weight training than with machines (SMD: -0.210, CI: -0.391, -0.029, p = 0.023), while strength in machine-based tests tended to increase more with machine training than with free-weights (SMD: 0.291, CI: -0.017, 0.600, p = 0.064). However, no differences were found between modalities in direct comparison (free-weight strength vs. machine strength) for dynamic strength (SMD: 0.084, CI: -0.106, 0.273, p = 0.387), isometric strength (SMD: -0.079, CI: -0.432, 0.273, p = 0.660), countermovement jump (SMD: -0.209, CI: -0.597, 0.179, p = 0.290) and hypertrophy (SMD: -0.055, CI: -0.397, 0.287, p = 0.751).

CONCLUSION

No differences were detected in the direct comparison of strength, jump performance and muscle hypertrophy. Current body of evidence indicates that strength changes are specific to the training modality, and the choice between free-weights and machines are down to individual preferences and goals.

A Comparison of Basic Training Variables in the Standard and Cambered Bar Bench Press Performed to Volitional Exhaustion

The objective of this study was to compare the impact of cambered and standard barbells used during the bench press exercise on the number of performed repetitions and mean velocity during a bench press training session that included 5 sets performed to volitional failure at 70% of one-repetition maximum (1RM) (for each barbell type). An additional objective was to determine whether there would be any difference in neuromuscular fatigue assessed by peak velocity changes during bench press throws performed 1 and 24 hours after the cessation of each session. The research participants included 12 healthy resistance-trained men. Participants performed 5 sets of the bench press exercise to volitional failure against 70% of 1RM with the cambered or standard barbell. The Friedman's test showed an overall trend of a significant decrease in the mean velocity (p < 0.001) and a number of performed repetitions (p < 0.001) from the first to the fifth set (p < 0.006 and p < 0.02, respectively for all) under both conditions, yet neither bar showed significant differences between the corresponding sets. Two-way ANOVA indicated a significant main effect of time (p < 0.001) for peak velocity during the bench press throw. The post-hoc comparisons showed significantly lower peak velocity during the bench press throw one hour after the bench press compared to pre (p = 0.003) and 24-hour post intervention (p = 0.007). Both barbells caused a similar decrease in peak barbell velocity during the bench press throw performed one hour after the bench press training session, with values returning to baseline 24 hours later. This indicates that bench press workouts with either a standard or a cambered barbell present the same training demands.

Which ROMs Lead to Rome? A Systematic Review of the Effects of Range of Motion on Muscle Hypertrophy

ABSTRACT

Kassiano, W, Costa, B, Nunes, JP, Ribeiro, AS, Schoenfeld, BJ, and Cyrino, ES. Which ROMs lead to Rome? a systematic review of the effects of range of motion on muscle hypertrophy. J Strength Cond Res XX(X): 000-000, 2022-Resistance exercise range of motion (ROM) influences muscular adaptations. However, there are no consistent practical guidelines about the optimal ROM for maximizing muscle hypertrophy. The objective of this article was to systematically review the literature for studies that compared the effects of full ROM (fROM) and partial ROM (pROM) on muscle hypertrophy. PubMed/MEDLINE, Scopus, and Web of Science databases were searched to identify articles from the earliest record up to and including April 2022. We calculated the effect size (ES) scores of the variables of interest. Eleven studies were included in the review. Full ROM and pROM performed in the initial part of the ROM elicited greater muscle hypertrophy of the rectus femoris, vastus lateralis, biceps brachii, and brachialis distal sites (between-groups ES: 0.20-0.90) than pROM performed in the final part of the ROM. fROM elicited greater muscle growth on the gluteus maximus and adductors than pROM in the final part of the ROM (between-groups ES: 0.24-0.25). Initial pROM produced more favorable proximal rectus femoris hypertrophy than fROM (between-groups ES: 0.35-0.38). pROM in the middle part of the ROM elicited greater triceps brachii hypertrophy than fROM (between-group ES: 1.21). In conclusion, evidence suggests that when training at a longer muscle length-through either pROM or fROM-some muscles, such as quadriceps femoris, biceps brachii, and triceps brachii, tend to experience optimal growth. Thus, the use pROM in the initial part of the excursion in combination with fROM training should be considered when prescribing hypertrophy-oriented resistance training programs.

Can Blood Flow Restriction Training Benefit Post-Activation Potentiation? A Systematic Review of Controlled Trials

(1) Background: post-activation potentiation (PAP) plays an essential role in enhancing athletic performance. Various conditioning activities (CAs) have been developed to generate PAP before training or competitions. However, whether extra equipment can enhance the effectiveness of CAs is understudied. Hence, this systematic review aims to introduce and examine the effectiveness of blood flow restriction-based conditioning activities (BFR-CAs). (2) Methods: a literature search was conducted via Web of Science, PubMed, SPORTDiscus, and CNKI (a Chinese academic database). The systematic review included the literature concerning BFR-CAs and non-BFR-CAs. The methodological quality of included studies was considered to be "moderate quality" and "good quality" based on the Physiotherapy Evidence Database Scale. (3) Results: five studies were included in this study. Four studies were on lower limb strength training, and three of them suggested a greater PAP in BFR-CAs than in non-BFR counterparts. One study on upper limb strength training also supported the advantage of BFR-CAs. (4) Conclusions: BFR-CAs may be an emerging and promising strategy to generate PAP. Compared with non-BFR-CAs, BFR-CAs might be more efficient and practical for inexperienced sports people or athletes in non-power sports.

Does Varying Resistance Exercises Promote Superior Muscle Hypertrophy and Strength Gains? A Systematic Review

ABSTRACT

Kassiano, W, Nunes, JP, Costa, B, Ribeiro, AS, Schoenfeld, BJ, and Cyrino, ES. Does varying resistance exercises promote superior muscle hypertrophy and strength gains? A systematic review. J Strength Cond Res 36(6): 1753-1762, 2022-Fitness professionals routinely employ a variety of resistance training exercises in program design as a strategy to enhance muscular adaptations. However, it remains uncertain whether such an approach offers advantages over a fixed-exercise selection. The objective of this review was to review the effects of exercise variation on muscle hypertrophy and strength. A search of the literature was conducted using PubMed/MEDLINE, Scopus, and Web of Science databases. Eight studies were identified as meeting inclusion criteria. The combined total sample of the studies was N = 241, comprising all young men. The methodological quality of included studies was considered "good" and "excellent" based on the Physiotherapy Evidence Database Scale. The available studies indicate that varying exercise selection can influence muscle hypertrophy and strength gains. Some degree of systematic variation seems to enhance regional hypertrophic adaptations and maximize dynamic strength, whereas excessive, random variation may compromise muscular gains. We conclude that exercise variation should be approached systematically with a focus on applied anatomical and biomechanical constructs; on the contrary, employing different exercises that provide a redundant stimulus, as well as excessive rotation of different exercises (i.e., high frequency of change), may actually hinder muscular adaptations.

Lean mass sparing in resistance-trained athletes during caloric restriction: the role of resistance training volume

Many sports employ caloric restriction (CR) to reduce athletes’ body mass. During these phases, resistance training (RT) volume is often reduced to accommodate recovery demands. Since RT volume is a well-known anabolic stimulus, this review investigates whether a higher training volume helps to spare lean mass during CR. A total of 15 studies met inclusion criteria. The extracted data allowed calculation of total tonnage lifted (repetitions × sets × intensity load) or weekly sets per muscle group for only 4 of the 15 studies, with RT volume being highly dependent on the examined muscle group as well as weekly training frequency per muscle group. Studies involving high RT volume programs (≥ 10 weekly sets per muscle group) revealed low-to-no (mostly female) lean mass loss. Additionally, studies increasing RT volume during CR over time appeared to demonstrate no-to-low lean mass loss when compared to studies reducing RT volume. Since data regarding RT variables applied were incomplete in most of the included studies, evidence is insufficient to conclude that a higher RT volume is better suited to spare lean mass during CR, although data seem to favor higher volumes in female athletes during CR. Moreover, the data appear to suggest that increasing RT volume during CR over time might be more effective in ameliorating CR-induced atrophy in both male and female resistance-trained athletes when compared to studies reducing RT volume. The effects of CR on lean mass sparing seem to be mediated by training experience, pre-diet volume, and energy deficit, with, on average, women tending to spare more lean mass than men. Potential explanatory mechanisms for enhanced lean mass sparing include a preserved endocrine milieu as well as heightened anabolic signaling.

A mixed-methods feasibility study of a sit-to-stand based exercise programme to maintain knee-extension muscle strength for older patients during hospitalisation

Objectives:

To determine the acceptability of an exercise programme and to identify barriers and facilitators to compliance with the programme from the participants’ perspective.

Methods:

Patients aged 75 years or older were recruited within the first 36 hours of hospital admission. Participants were randomised to complete two strengthening-based (intervention arm) or stretching-based (control arm) exercise sessions per-day. At hospital discharge, participants were asked to take part in interviews with a member of the research team exploring the barriers and facilitators to adherence to the intervention.

Results:

15 participants (7 intervention arm, 8 control arm) were recruited before the trial was stopped due to COVID-19. Both groups showed reductions in knee-extension strength, and improvements in functional mobility at discharge from hospital. A total of 23/60 intervention sessions were classed as ‘complete’, 12/60 as partially complete, and 25/60 were missed entirely. Eight participants took part in interviews. Intrinsic factors that impacted participation in the research, related to current health, health beliefs, and experience of multi-morbidity or functional decline. Staff had both a positive and negative effect on participant adherence to the intervention.

Conclusions:

The exercise intervention was well received, with most participants describing health benefits, though intervention fidelity was lower than expected.

Elbow Joint Angles in Elbow Flexor Unilateral Resistance Exercise Training Determine Its Effects on Muscle Strength and Thickness of Trained and Non-trained Arms

The present study compared two unilateral arm curl resistance exercise protocols with a different starting and finishing elbow joint angle in the same ROM for changes in elbow flexors strength and muscle thickness of the trained and non-trained arms. Thirty-two non-resistance trained young adults were randomly assigned to one of the three groups: extended joint training (0°–50°; EXT, n = 12); flexed joint training (80°–130°; FLE, n = 12); and non-training control (n = 8). The exercise training was performed by the dominant arms twice a week for 5 weeks with gradual increases in the training volume over 10 training sessions, and the non-dominant (non-trained) arms were investigated for the cross-education effect. Maximal voluntary contraction torque of isometric (MVC-ISO), concentric (MVC-CON), and eccentric contractions (MVC-ECC), and thickness (MT) of biceps brachii and brachialis of the trained and non-trained arms were assessed at baseline and 4–8 days after the last training session. The control group did not show significant changes in any variables. Significant (P < 0.05) increases in MVC-ISO torque (16.2 ± 12.6%), MVC-CON torque (21.1 ± 24.4%), and MVC-ECC torque (19.6 ± 17.5%) of the trained arm were observed for the EXT group only. The magnitude of the increase in MT of the trained arm was greater (P < 0.05) for EXT (8.9 ± 3.9%) than FLE (3.4 ± 2.7%). The cross-education effect was evident for MVC-ISO (15.9 ± 14.8%) and MVC-CON (16.7 ± 20.0%) torque of the EXT group only. These results suggest that resistance training at the extended elbow joint induces greater muscle adaptations and cross-education effects than that at flexed elbow joint.

Range of motion of resistance exercise affects the number of performed repetitions but not a time under tension

The resistance training volume along with the exercise range of motion has a significant impact on the training outcomes. Therefore, this study aimed to examine differences in training volume assessed by a number of performed repetitions, time under tension, and load-displacement as well as peak barbell velocity between the cambered and standard barbell bench press training session. The participants performed 3 sets to muscular failure of bench press exercise with the cambered or standard barbell at 50% of one-repetition maximum (1RM). Eighteen healthy men volunteered for the study (age = 25 ± 2 years; body mass = 92.1 ± 9.9 kg; experience in resistance training 7.3 ± 2.1 years; standard and cambered barbell bench press 1RM > 120% body mass). The t-test indicated a significantly higher mean range of motion for the cambered barbell in comparison to the standard (p < 0.0001; ES =  -2.24). Moreover, there was a significantly greater number of performed repetitions during the standard barbell bench press than cambered barbell (p < 0.0001) in a whole training session, while no difference was found in total time under tension (p = 0.22) and total load-displacement (p = 0.913). The two-way repeated-measures ANOVA indicated a significant barbell × set interaction effect for peak velocity (p = 0.01) and a number of repetitions (p = 0.015). The post-hoc analysis showed a significantly higher number of repetitions for standard than cambered barbell bench press in set 1 (p < 0.0001), set 3 (p < 0.0001) but not in set 2 (p = 0.066). Moreover, there was a significantly higher peak velocity during the cambered than standard barbell bench press in set 1 (p < 0.0001), and set 2 (p = 0.049), but not in set 3 (p = 0.063). No significant differences between corresponding sets of the standard and cambered barbell bench press in time under tension and load-displacement were found. However, concentric time under tension was significantly higher during cambered barbell bench press in all sets (p < 0.05) when compared to the standard barbell bench press, while eccentric time under tension was significantly lower during the cambered than standard barbell bench presses only in the set 3 (p = 0.001). In summary, this study briefly showed that measuring training volume by the number of performed repetitions is not reliable when different exercise range of motion is used.

Effects of range of motion on resistance training adaptations: A systematic review and meta-analysis

BACKGROUND

Nowadays, there is a lack of consensus and high controversy about the most effective range of motion (ROM) to minimize the risk of injury and maximize the resistance training adaptations.

OBJECTIVE

To conduct a systematic review and meta-analysis of the scientific evidence examining the effects of full and partial ROM resistance training interventions on neuromuscular, functional, and structural adaptations.

METHODS

The original protocol (CRD42020160976) was prospectively registered in the PROSPERO database. Medline, Scopus, and Web of Science databases were searched to identify relevant articles from the earliest record up to and including March 2021. The RoB 2 and GRADE tools were used to judge the level of bias and quality of evidence. Meta-analyses were performed using robust variance estimation with small-sample corrections.

RESULTS

Sixteen studies were finally included in the systematic review and meta-analyses. Full ROM training produced significantly greater adaptations than partial ROM on muscle strength (ES = 0.56, p = 0.004) and lower-limb hypertrophy (ES = 0.88, p = 0.027). Furthermore, although not statistically significant, changes in functional performance were maximized by the full ROM training (ES = 0.44, p = 0.186). Finally, no significant superiority of either ROM was found to produce changes in muscle thickness, pennation angle, and fascicle length (ES = 0.28, p = 0.226).

CONCLUSION

Full ROM resistance training is more effective than partial ROM to maximize muscle strength and lower-limb muscle hypertrophy. Likewise, functional performance appears to be favored by the use of full ROM exercises. On the contrary, there are no large differences between the full and partial ROM interventions to generate changes in muscle architecture.

Partial range of motion training elicits favorable improvements in muscular adaptations when carried out at long muscle lengths

The study compared changes in strength and regional muscle hypertrophy between different ranges of motion (ROM) in the knee extension exercise. Forty-five untrained women were randomized to either a control group or to perform the exercise in one of the following 4 groups (0°=extended knee): Full ROM (FULL_ROM: 100°-30° of knee flexion); Initial Partial ROM (INITIAL_ROM: 100°-65°); Final Partial ROM (FINAL_ROM: 65°-30°); Varied ROM (VAR_ROM: daily alternation between the ROM of INITIAL_ROM and FINAL_ROM). Pre- and post-training assessments included one repetition maximum (1RM) testing in the ROM corresponding to the initial, final and full ROM, and measurement of cross-sectional areas of the rectus femoris and vastus lateralis muscles at 40%, 50%, 60% and 70% of femur length in regard to regional muscle hypertrophy. Results showed that the INITIAL_ROM group presented a greater relative increase than all groups at 70%, and at 50% and 60% the increases were greater than FINAL_ROM, FULL_ROM, and non-training control (CON) groups. Moreover, FINAL_ROM group presented similar changes compared to the CON group at 60% and 70%. In regard to 1RM, FINAL_ROM and INITIAL_ROM groups presented greater relative increases at the ROM trained, and no group showed greater increases than VAR_ROM or INITIAL_ROM, regardless the ROM tested. In conclusion, partial ROM training in the initial phase of the knee extension exercise promoted greater relative hypertrophy in certain muscle regions than training in other ROM configurations, and no group promoted a greater 1RM increase than VAR_ROM group, which showed similar 1RM increases in the different ROMs tested.

Evidenz von Trainingsempfehlungen für ein Hypertrophietraining

Der Abbau der Skelettmuskulatur steigt mit zunehmendem Alter und wird in der heutigen Gesellschaft aufgrund geringerer körperlicher Aktivität zusätzlich beschleunigt. Die Skelettmuskulatur ist vor allem für die Übertragung von Kräften und somit für unsere alltäglichen Bewegungen verantwortlich. Mit der Reduzierung der Muskelmasse wird die Durchführung von Alltagsbewegungen kontinuierlich erschwert, und die Lebensqualität kann dadurch deutlich sinken. Mit Kraft- bzw. Hypertrophietraining kann jedoch einer Muskelatrophie entgegengewirkt werden, indem Abbauprozesse verlangsamt werden und die Skelettmuskulatur wieder aufgebaut wird. Trainingsempfehlungen für ein Hypertrophietraining variieren jedoch erheblich. Dieser Artikel soll vor allem den aktuellen Forschungstand zusammenfassen und praxisrelevante Empfehlungen aussprechen.

Der entscheidendste Aspekt beim Hypertrophietraining scheint lediglich das Setzen von regelmäßigen progressiven und erschöpfenden Belastungsreizen zu sein, die mindestens einen Wirkungsmechanismus aktivieren, der für hypertrophe Effekte verantwortlich ist. Vor allem die Variation der mechano-biologischen Deskriptoren (Trainingswiderstand, Anzahl Wiederholungen und Sätze, Pause etc.) könnte helfen, langfristig effektive Reize zu gestalten. Dabei kann nahezu auf unbegrenzte Kombinationsmöglichkeiten zurückgegriffen werden, welche jedoch dem Leistungsniveau und der Belastbarkeit der trainierenden Person sowie der Umsetzbarkeit im Alltag angepasst werden müssen. Nach dem Motto „viele Wege führen nach Rom“ gibt es dabei nicht nur eine konkrete Lösung bei der Planung und Durchführung eines Hypertrophietrainings. Es ist eher von essenzieller Bedeutung, dass kontinuierliche Belastungsreize in unterschiedlichen Variationen durchgeführt werden, um einen Hypertrophieeffekt zu erzeugen und folglich dem Abbau der Skelettmuskulatur entgegenzuwirken.

Understanding Bench Press Biomechanics-The Necessity of Measuring Lateral Barbell Forces

ABSTRACT

Mausehund, L, Werkhausen, A, Bartsch, J, and Krosshaug, T. Understanding bench press biomechanics-The necessity of measuring lateral barbell forces. J Strength Cond Res XX(X): 000-000, 2020-The purpose of this study was to advance the expertise of the bench press exercise by complementing electromyographic (EMG) with net joint moment (NJM) and strength normalized NJM (nNJM) measurements, thus establishing the magnitude of the elbow and shoulder muscular loads and efforts. Normalized NJMs were determined as the ratio of the bench press NJMs to the maximum NJMs produced during maximum voluntary isokinetic contractions. Furthermore, we wanted to assess how changes in grip width and elbow positioning affected elbow and shoulder NJMs and nNJMs, and muscle activity of the primary movers. Thirty-five strength-trained adults performed a 6-8 repetition maximum set of each bench press variation, while elbow and shoulder NJMs and EMG activity of 7 upper extremity muscles were recorded. The results show that all bench press variations achieved high elbow and shoulder muscular efforts. A decrease in grip width induced larger elbow NJMs, and larger EMG activity of the lateral head of the triceps brachii, anterior deltoid, and clavicular head of the pectoralis major (p ≤ 0.05). An increase in grip width elicited larger shoulder NJMs and nNJMs, and larger EMG activity of the abdominal head of the pectoralis major (p ≤ 0.05). In conclusion, all bench press variations may stimulate strength gains and hypertrophy of the elbow extensors and shoulder flexors and horizontal adductors. However, greater adaptations of the elbow extensors and shoulder flexors may be expected when selecting narrower grip widths, whereas wider grip widths may induce greater adaptations of the shoulder horizontal adductors.

Adaptations to explosive resistance training with partial range of motion are not inferior to full range of motion

We tested whether explosive resistance training with partial range of motion (ROM) would be as effective as full ROM training using a noninferiority trial design. Fifteen subjects with strength training experience took part in an explosive-concentric only-leg press training program, three times per week for 10 weeks. One leg was randomly assigned to exercise with partial ROM (ie, 9º) and the other leg to full ROM. Before and after training, we assessed leg press performance, isokinetic concentric and isometric knee extension torque, and vastus lateralis muscle architecture. Overall, both training modalities increased maximal strength and rate of force development. Training with partial ROM yielded noninferior results compared to full ROM for leg press peak power (+69 ± 47% vs. +61 ± 64%), isokinetic strength (4-6 ± 6%-12% vs. 1-6 ± 6%-10% at 30, 60, and 180˚s^-1 ), and explosive torque after 100 (47 ± 24 vs. 35 ± 22) and 150 ms (57 ± 22% vs. 42 ± 25%). The comparison was inconclusive for other functional parameters (ie, isokinetic peak torque (300˚s^-1 ), joint angle at isokinetic peak torque, explosive torque after 50 ms, and electrically evoked torque) and for muscle fascicle length and thickness, although noninferiority was established for pennation angle. However, partial ROM was not found statistically inferior to full ROM for any measured variable. Under the present conditions, the effects of explosive heavy resistance training were independent of joint ROM. Instead, these data suggest that the distinct timing of muscle work in explosive contractions confers more influence to the starting joint angle than ROM on adaptations to this type of training.

Can the Cambered Bar Enhance Acute Performance in the Bench Press Exercise?

The main goal of this study was to assess the impact of the cambered bar (CB) during the bench press exercise on power output and bar velocity when compared to a standard bar (SB). Ten healthy strength-trained men (age = 27.9 ± 3.7 years; body mass = 90.1 ± 12.5 kg; resistance training experience = 6.5 ± 2.7 years; bench press one-repetition maximum (1RM) = 118.5 ± 21 kg) performed a single set of 3 repetitions of the bench press exercise with an SB and a CB at 50%1RM to assess differences in peak power output (PP), mean power output (MP), peak bar velocity (PV), and mean bar velocity (MV), range of motion (ROM), and positive work time under load (TUL) between conditions. The t-test indicated significantly higher mean ROM for the cambered bar in comparison to the standard bar (52.7 vs. 44.9 cm; P < 0.01; ES = 1.40). Further, there was a significantly higher PP (907 vs. 817 W; P < 0.01; ES = 0.35), MP (556 vs. 496 W; P < 0.01; ES = 0.46), PV (1.24 vs. 1.14 m/s; P < 0.01; ES = 0.35) and MV (0.89 vs. 0.82 m/s; P < 0.01; ES = 0.34) for the CB condition when compared to the SB. A significantly longer TUL for the CB was observed, when compared to the SB (1.89 vs. 1.51 s; P < 0.01; ES = 1.38). The results of this study showed that the CB significantly increased power output and bar velocity in the bench press exercise at 50%1RM compared to the SB. Therefore, the additional ROM, made possible through the use of the CB, allows for the acceleration of the bar through a significantly longer displacement, which has a positive impact on power output. However, a simultaneous increase in TUL may cause higher fatigue when the bench press is performed with the CB compared to the SB.

Proposal of Dental Hygiene Diagnosis for Cancer Patients Based on Dental Hygiene Process of Care in Acute Care Hospitals: A Narrative Review

A narrative review was conducted to propose dental hygiene diagnoses for cancer patients based on dental hygiene process of care in acute care hospitals. Six researchers, including three dental hygienists, all with expertise in oral healthcare for patients with cancer, decided the review outline. All researchers reviewed the literature and developed terminology for dental hygiene diagnoses. The team then modified the terminology and discussed its clarity and acceptability to develop an initial list of dental hygiene diagnosis names according to the dental hygiene human needs conceptual model subscales. In wholesome facial image, one new diagnosis was developed. In protection from health risks, 15 new diagnoses were developed. In biologically sound and functional dentition, 10 new diagnoses were developed. In skin and mucous membrane integrity of the head and neck, 10 new diagnoses were developed. In freedom from head and neck pain, two new diagnoses were developed. In freedom from anxiety and stress, eight new diagnoses were developed. In responsibility for oral health, five new diagnoses were developed. In conceptualization and understanding, three new diagnoses were developed. Based on this study, it is necessary for the academic community to develop a better taxonomy of dental hygiene diagnoses pertaining to dental hygienist clinical practice.

A Comparison of Muscle Activity Between the Cambered and Standard Bar During the Bench Press Exercise

The aim of this study was to compare the electromyographic activity between the standard and cambered bar during the bench press (BP) exercise. Twelve resistance-trained males performed the flat BP with a standard and a cambered bar at selected loads (50%, 70%, and 90% 1RM). Muscle activation assessed by surface electromyography (sEMG) was recorded for the pectoralis major, anterior deltoid, and the lateral and long heads of the triceps brachii during each attempt. A three-way repeated measures ANOVA indicated statistically significant main interaction for bar × load × muscle (p < 0.01); bar × load (p < 0.01); bar × muscle (p < 0.01); load × muscle (p < 0.01). There was also a main effect for the bar (p < 0.01); load (p < 0.01); and muscle group (p < 0.01). The post hoc analysis for the main multiple interaction effect of bar × load × muscle showed a statistically significant increase in sEMG for the standard bar in the pectoralis major compared to the cambered bar at 50% 1RM (p < 0.01) and 90% 1RM (p < 0.01), as well as in the triceps brachii long at 90% 1RM (p < 0.01). Furthermore, a statistically significant decrease in sEMG was registered for the standard bar in the anterior deltoid compared to the cambered bar at 90% 1RM (p = 0.02). The results indicated that the cambered bar was superior in activating the anterior deltoid muscle compared to the standard bar during the BP exercise, whereas the standard bar provided higher pectoralis major and triceps brachii long head sEMG activity at 90% 1RM.