Training for strength and hypertrophy: an evidence-based approach

The Role of Musculoskeletal Training During Return to Performance Following Relative Energy Deficiency in Sport

BACKGROUND

Relative energy deficiency in sport (REDs) is a condition that is associated with negative health and performance outcomes in athletes. Insufficient energy intake relative to exercise energy expenditure, resulting in low energy availability, is the underlying cause, which triggers numerous adverse physiological consequences including several associated with musculoskeletal (MSK) health and neuromuscular performance.

PURPOSE

This commentary aims to (1) discuss the health and performance implications of REDs on the skeletal and neuromuscular systems and (2) examine the role that MSK training (ie, strength and plyometric training) during treatment and return to performance following REDs might have on health and performance in athletes, with practical guidelines provided.

CONCLUSIONS

REDs is associated with decreases in markers of bone health, lean body mass, maximal and explosive strength, and muscle work capacity. Restoration of optimal energy availability, mainly through an increase in energy intake, is the primary goal during the initial treatment of REDs with a return to performance managed by a multidisciplinary team of specialists. MSK training is an effective nonpharmacological component of treatment for REDs, which offers multiple long-term health and performance benefits, assuming the energy needs of athletes are met as part of their recovery. Supervised, prescribed, and gradually progressive MSK training should include a combination of resistance training and high-impact plyometric-based exercise to promote MSK adaptations, with an initial focus on achieving movement competency. Progressing MSK training exercises to higher intensities will have the greatest effects on bone health and strength performance in the long term.

Effect of Step Load Based on Time under Tension in Hypoxia on the ACL Pre-Operative Rehabilitation and Hormone Levels: A Case Study

The aim of the study was to determine the effect of step load in hypoxia on the effectiveness of preoperative rehabilitation (PR) and hormone levels based on a case study. Introduction: We assessed the impact of variables such as rate of movement and time under tension (TUT) in normobaric hypoxia on the levels of growth hormone (GH), insulin-like growth factor 1 (IGF-1), and erythropoietin (EPO). Additionally, the impact of step load on the hypertrophy and strength of knee extensors and flexors was assessed. Methods: The work uses a case study, the research subject of which was a 23-year-old female professional handball player. The tests included an isokinetic assessment of the peak torque of knee extensors and flexors as well as body composition analysis. Results: The results showed a more than (10.81-fold) increase in GH after the microcycle with time under tension (TUT). The deficit between the lower limbs was also reduced. Conclusions: Using a hypoxic environment based on an appropriate altitude, combined with changes such as a short rest break between sets and a controlled tempo of movement with an eccentric phase, TUT may offer an alternative to the PR process, especially among athletes who care about fast RTS.

Optimizing competence in the service of collaboration

In order to efficiently divide labor with others, it is important to understand what our collaborators can do (i.e., their competence). However, competence is not static-people get better at particular jobs the more often they perform them. This plasticity of competence creates a challenge for collaboration: For example, is it better to assign tasks to whoever is most competent now, or to the person who can be trained most efficiently "on-the-job"? We conducted four experiments (N=396) that examine how people make decisions about whom to train (Experiments 1 and 3) and whom to recruit (Experiments 2 and 4) to a collaborative task, based on the simulated collaborators' starting expertise, the training opportunities available, and the goal of the task. We found that participants' decisions were best captured by a planning model that attempts to maximize the returns from collaboration while minimizing the costs of hiring and training individual collaborators. This planning model outperformed alternative models that based these decisions on the agents' current competence, or on how much agents stood to improve in a single training step, without considering whether this training would enable agents to succeed at the task in the long run. Our findings suggest that people do not recruit and train collaborators based solely on their current competence, nor solely on the opportunities for their collaborators to improve. Instead, people use an intuitive theory of competence to balance the costs of hiring and training others against the benefits to the collaboration.

Effects of once- versus twice-weekly eccentric resistance training on muscular function and structure in older adults: a randomised controlled trial

Adherence rates to current twice-weekly strength training guidelines are poor among older adults. Eccentric-only training elicits substantial improvements in muscle function/size so the aim of this study was to compare the effects of once- versus twice-weekly eccentric training programmes on muscle function/size in older adults. Thirty-six participants (69.4 ± 6.0 yr) were randomised into non-active control, once-, or twice-weekly training groups. Lower-limb muscle power, strength, and size were assessed at baseline, mid-, and post-eccentric training. Training was performed for 12 min per session at 50% of maximum eccentric strength. Significant increases in power (13%), isometric (17-36%) and eccentric (40-50%) strength, and VL muscle thickness (9-18%) occurred in both training groups following 12 weeks. Minimal muscle soreness was induced throughout the 12 weeks and perceived exertion was consistently lower in the twice-weekly training group. One weekly submaximal eccentric resistance training session over 12 weeks elicits similar improvements in neuromuscular function compared to the currently recommended twice-weekly training dose. Given the substantial improvements in neuromuscular function and previously reported low adherence to current twice-weekly training guidelines, eccentric training may be pivotal to developing a minimal-dose strategy to counteract neuromuscular decline. The trial was registered retrospectively on 24/01/2024 with ISRCTN (trial registration number: ISRCTN68730580).

The Plateau in Muscle Growth with Resistance Training: An Exploration of Possible Mechanisms

It is hypothesized that there is likely a finite ability for muscular adaptation. While it is difficult to distinguish between a true plateau following a long-term training period and short-term stalling in muscle growth, a plateau in muscle growth has been attributed to reaching a genetic potential, with limited discussion on what might physiologically contribute to this muscle growth plateau. The present paper explores potential physiological factors that may drive the decline in muscle growth after prolonged resistance training. Overall, with chronic training, the anabolic signaling pathways may become more refractory to loading. While measures of anabolic markers may have some predictive capabilities regarding muscle growth adaptation, they do not always demonstrate a clear connection. Catabolic processes may also constrain the ability to achieve further muscle growth, which is influenced by energy balance. Although speculative, muscle cells may also possess cell scaling mechanisms that sense and regulate their own size, along with molecular brakes that hinder growth rate over time. When considering muscle growth over the lifespan, there comes a point when the anabolic response is attenuated by aging, regardless of whether or not individuals approach their muscle growth potential. Our goal is that the current review opens avenues for future experimental studies to further elucidate potential mechanisms to explain why muscle growth may plateau.

Acute Effect of the "Zero Point" Method on Muscle Thickness and Muscle Damage in Trained Men

The "zero point" method allows for lower intensities for an exercise session without impairing the total training volume. This study aimed to compare the effects of the "zero point" versus the traditional method on muscle responses and muscle damage in trained men. Fifteen experienced men (age: 27.7 ± 6.4 years; body mass: 78.4 ± 11.4 kg; height: 174.8 ± 4.9 cm; experience: 5.86 ± 4.7 years; relative bench press strength: 1.38 ± 0.17 kg·kg-1) were subjected to two exercise protocols in a randomized order and separated by a week. The traditional and "zero point" methods were applied in the bench press, with loads of 70% and 50% of one repetition maximum (1RM), respectively, for 10 sets until concentric failure, with 3-min intervals between sets. The zero point method displayed a higher number of repetitions and time under tension than the traditional method, with no difference in the total training volume, echo intensity, algometry, lactate, and myoglobin. For the muscle thickness, no differences between the groups were presented, except for the deltoid muscle thickness, in which a higher post-training volume was observed compared to traditional training. The "zero point" method increases the demand on the deltoid muscles in the bench press exercise, but not on the pectoralis and triceps brachii.

Resistance training prescription for muscle strength and hypertrophy in healthy adults: a systematic review and Bayesian network meta-analysis

OBJECTIVE

To determine how distinct combinations of resistance training prescription (RTx) variables (load, sets and frequency) affect muscle strength and hypertrophy.

DATA SOURCES

MEDLINE, Embase, Emcare, SPORTDiscus, CINAHL, and Web of Science were searched until February 2022.

ELIGIBILITY CRITERIA

Randomised trials that included healthy adults, compared at least 2 predefined conditions (non-exercise control (CTRL) and 12 RTx, differentiated by load, sets and/or weekly frequency), and reported muscle strength and/or hypertrophy were included.

ANALYSES

Systematic review and Bayesian network meta-analysis methodology was used to compare RTxs and CTRL. Surface under the cumulative ranking curve values were used to rank conditions. Confidence was assessed with threshold analysis.

RESULTS

The strength network included 178 studies (n=5097; women=45%). The hypertrophy network included 119 studies (n=3364; women=47%). All RTxs were superior to CTRL for muscle strength and hypertrophy. Higher-load (>80% of single repetition maximum) prescriptions maximised strength gains, and all prescriptions comparably promoted muscle hypertrophy. While the calculated effects of many prescriptions were similar, higher-load, multiset, thrice-weekly training (standardised mean difference (95% credible interval); 1.60 (1.38 to 1.82) vs CTRL) was the highest-ranked RTx for strength, and higher-load, multiset, twice-weekly training (0.66 (0.47 to 0.85) vs CTRL) was the highest-ranked RTx for hypertrophy. Threshold analysis demonstrated these results were extremely robust.

CONCLUSION

All RTx promoted strength and hypertrophy compared with no exercise. The highest-ranked prescriptions for strength involved higher loads, whereas the highest-ranked prescriptions for hypertrophy included multiple sets.

PROSPERO REGISTRATION NUMBER

CRD42021259663 and CRD42021258902.

Clinic and Home-Based Exercise with Blood Flow Restriction Resolves Thigh Muscle Atrophy after Anterior Cruciate Ligament Reconstruction with the Bone-Patellar Tendon-Bone Autograft: A Case Report

Anterior cruciate ligament reconstruction (ACLR) results in thigh muscle atrophy. Of the various interventions proposed to mitigate thigh muscle atrophy, exercise with blood flow restriction (BFR) appears safe and effective. Some literature suggests daily exposure to exercise with BFR may be indicated during the early phase of ACLR rehabilitation; this case report outlines the methodology utilized to prescribe clinic- and home-based BFR within an outpatient rehabilitation program. A 15-year-old male soccer player suffered a left knee injury involving the anterior cruciate ligament and both menisci. He underwent ACLR and completed exercise with BFR as part of his clinic- and home-based rehabilitation program, which included practical blood flow restriction during home-based rehabilitation. After 16 weeks of rehabilitation, surgical limb thigh girth values were objectively larger than the non-surgical limb (surgical, 52.25 cm; non-surgical 50 cm), as well as the multi-frequency bioelectrical impedance analysis of his lower-extremity lean body mass (surgical limb, 10.37 kg; non-surgical limb, 10.02 kg). The findings of this case report suggest that the inclusion of clinic- and home-based BFR within an outpatient rehabilitation program may be indicated to resolve thigh muscle atrophy early after ACLR.

Biceps Brachii and Brachioradialis Excitation in Biceps Curl Exercise: Different Handgrips, Different Synergy

The current study analyzed the excitation of biceps brachii, brachioradialis, and anterior deltoid during bilateral biceps curl performed with different handgrips. Ten competitive bodybuilders performed bilateral biceps curl in non-exhaustive 6-rep sets using 8-RM with the forearm in supinated, pronated, and neutral positions. The ascending and descending phase of each variation was separately analyzed using the normalized root mean square collected using surface electromyography. During the ascending phase, (i) biceps brachii excitation was greater with the supinated compared to the pronated [+19(7)%, ES: 2.60] and neutral handgrip [+12(9)%, ES: 1.24], (ii) the brachioradialis showed greater excitation with the supinated compared to the pronated [+5(4)%, ES: 1.01] and neutral handgrip [+6(5)%, ES: 1.10], (iii) the anterior deltoid excitation was greater with the pronated and neutral handgrip compared to the supinated condition [+6(3)% and +9(2)%, ES: 2.07 and 3.18, respectively]. During the descending phase, the anterior deltoid showed greater excitation in the pronated compared to the supinated handgrip [+5(4)%, ES: 1.02]. Changing the handgrips when performing biceps curl induces specific variations in biceps brachii and brachioradialis excitation and requires different anterior deltoid interventions for stabilizing the humeral head. Practitioners should consider including different handgrips in the biceps curl routine to vary the neural and mechanical stimuli.

Success factors of evidence-based training for pilots

Training pilots is a long-lasting and important task for the aviation safety and proper operation of airlines. Evidence-Based Training (EBT) is proposed as one of the best alternatives for pilot training. This study identified the need of EBT in terms of non-technical performance training for pilots. The purpose of this paper is to identify the need to introduce a new training system, the EBT model, and to assess and verify its performance by operating airlines to assist in decision making by airlines considering the introduction of EBT. A total of 1003 people were subjected to the study, including 557 captains and 446 co-pilots of each model who responded to the survey conducted after EBT. Results of the survey were analyzed through multiple regression analysis to confirm the validity of this model, and the pilots who were trained were also satisfied with EBT. The results show that the training program information and the system quality have a positive effect on the satisfaction of the trainee and the enhancement of the trainee's perceived ability. The results of this research contribute a positive basis for EBT. The implication of this study is that the proper provision of training program and the better system could support the performance of training for pilots.

Training in the Initial Range of Motion Promotes Greater Muscle Adaptations Than at Final in the Arm Curl

OBJECTIVE

The effects of ROM manipulation on muscle strength and hypertrophy response remain understudied in long-term interventions. Thus, we compared the changes in strength and regional muscle hypertrophy after training in protocols with different ranges of motion (ROM) in the seated dumbbell preacher curl exercise using a within-participant experimental design.

DESIGN AND METHODS

Nineteen young women had one arm randomly assigned to train in the initial ROM (INITIAL_ROM: 0°-68°; 0° = extended elbow) while the contralateral arm trained in the final ROM (FINAL_ROM: 68°-135°), three times per week over an eight-week study period. Pre- and post-training assessments included one repetition maximum (1RM) testing in the full ROM (0°-135°), and measurement of biceps brachii cross-sectional area (CSA) at 50% and 70% of humerus length. Paired t-tests were used to compare regional CSA changes between groups, the sum of CSA changes at 50% and 70% (CSA_summed), and the strength response between the training protocols.

RESULTS

The INITIAL_ROM protocol displayed a greater CSA increase than FINAL_ROM protocol at 70% of biceps length (p = 0.001). Alternatively, we observed similar increases between the protocols for CSA at 50% (p = 0.311) and for CSA_summed (p = 0.111). Moreover, the INITIAL_ROM protocol displayed a greater 1RM increase than FINAL_ROM (p < 0.001).

CONCLUSIONS

We conclude that training in the initial angles of elbow flexion exercise promotes greater distal hypertrophy of the biceps brachii muscle in untrained young women. Moreover, the INITIAL_ROM condition promotes a greater dynamic strength increase when tested at a full ROM compared to the FINAL_ROM.

Bilateral Biceps Curl Shows Distinct Biceps Brachii and Anterior Deltoid Excitation Comparing Straight vs. EZ Barbell Coupled with Arms Flexion/No-Flexion

The present study investigated the excitation of the biceps brachii and anterior deltoid during bilateral biceps curl performed using the straight vs. EZ barbell and with or without flexing the arms. Ten competitive bodybuilders performed bilateral biceps curl in non-exhaustive 6-rep sets using 8-RM in four variations: using the straight barbell flexing (ST_flex) or not flexing the arms (ST_no-flex) or the EZ barbell flexing (EZ_flex) or not flexing the arms (EZ_no-flex). The ascending and descending phases were separately analyzed using the normalized root mean square (nRMS) collected using surface electro-myography. For the biceps brachii, during the ascending phase, a greater nRMS was observed in ST_no-flex vs. EZ_no-flex (+1.8%, effect size [ES]: 0.74), in ST_flex vs. ST_no-flex (+17.7%, ES: 3.93) and in EZ_flex vs. EZ_no-flex (+20.3%, ES: 5.87). During the descending phase, a greater nRMS was observed in ST_flex vs. EZ_flex (+3.8%, ES: 1.15), in ST_no-flex vs. ST_flex (+2.8%, ES: 0.86) and in EZ_no-flex vs. EZ_flex (+8.1%, ES: 1.81). The anterior deltoid showed distinct excitation based on the arm flexion/no-flexion. A slight advantage in biceps brachii excitation appears when using the straight vs. EZ barbell. Flexing or not flexing the arms seems to uniquely excite the biceps brachii and anterior deltoid. Practitioners should consider including different bilateral biceps barbell curls in their routine to vary the neural and mechanical stimuli.

Resistance Training for Patients with Cancer: A Conceptual Framework for Maximizing Strength, Power, Functional Mobility, and Body Composition to Optimize Health and Outcomes

There are many benefits to the addition of exercise to cancer treatment and survivorship, particularly with resistance training regimens that target hypertrophy, bone mineral density, strength, functional mobility, and body composition. These goals are best achieved through a series of individualized high-intensity compound movements that mirror functional mobility patterns and sufficiently stress the musculoskeletal system. As a result of adequate stress, the body will engage compensatory cellular mechanisms that improve the structural integrity of bones and muscles, stimulate metabolism and the immune system, optimize functional performance, and minimize mechanical injury risk. The current evidence suggests that application of the above exercise principles, practiced in a safe environment under expert observation, may offer patients with cancer an effective means of improving overall health and cancer-specific outcomes. The following article poses several important questions certified exercise specialists and physicians should consider when prescribing resistance exercise for patients with cancer.

Appropriate Reporting of Exercise Variables in Resistance Training Protocols: Much more than Load and Number of Repetitions

Manipulating resistance training variables is crucial to plan the induced stimuli correctly. When reporting the exercise variables in resistance training protocols, sports scientists and practitioners often refer to the load lifted and the total number of repetitions. The present conceptual review explores all within-exercise variables that may influence the strength and hypertrophic gains, and the changes in muscle architecture. Together with the (1) load and (2) the number of repetitions, (3) performing repetitions to failure or not to failure, (4) the displacement of the load or the range of movement (full or partial), (5) the portion of the partial movement to identify the muscle length at which the exercise is performed, (6) the total time under tension, the duration of each phase and the position of the two isometric phases, (7) whether the concentric, eccentric or concentric-eccentric phase is performed, (8) the use of internal or external focus and (9) the inter-set rest may all have repercussions on the adaptations induced by each resistance exercise. Manipulating one or more variable allows to increase, equalize or decrease the stimuli related to each exercise. Sports scientists and practitioners are invited to list all aforementioned variables for each exercise when reporting resistance training protocols.

Triceps brachii hypertrophy is substantially greater after elbow extension training performed in the overhead versus neutral arm position

The biarticular triceps brachii long head (TB_Long) is lengthened more in the overhead than neutral arm position. We compared triceps brachii hypertrophy after elbow extension training performed in the overhead vs. neutral arm position. Using a cable machine, 21 adults (14 males and 7 females, age: 23.4 ± 1.6 y, height: 1.69 ± 0.09 m, body mass: 64.5 ± 12.4 kg) conducted elbow extensions (90-0°) with one arm in the overhead (Overhead-Arm) and the other arm in the neutral (Neutral-Arm) position at 70% one-repetition maximum (1RM), 10 reps/set, 5 sets/session, 2 sessions/week for 12 weeks. Training load was gradually increased (+5% 1RM/session) when the preceding session was completed without repetition failure. 1RM of the assigned condition and MRI-measured muscle volume of the TB_Long, monoarticular lateral and medial heads (TB_Lat+Med), and whole triceps brachii (Whole-TB) were assessed pre- and post-training. Training load and 1RM increased in both arms similarly (+62-71% at post, P = 0.285), while their absolute values/weights were always lower in Overhead-Arm (-34-39%, P < 0.001). Changes in muscle volume in Overhead-Arm compared to Neutral-Arm were 1.5-fold greater for the TB_Long (+28.5% vs. +19.6%, Cohen's d = 1.272, P < 0.001), 1.4-fold greater for the TB_Lat+Med (+14.6% vs. +10.5%, d = 1.106, P = 0.002), and 1.4-fold greater for the Whole-TB (+19.9% vs. +13.9%, d = 1.427, P < 0.001). In conclusion, triceps brachii hypertrophy was substantially greater after elbow extension training performed in the overhead versus neutral arm position, even with lower absolute loads used during the training.

Exercise-Induced Circulating microRNAs: Potential Key Factors in the Control of Breast Cancer

Losses in skeletal muscle mass, strength, and metabolic function are harmful in the pathophysiology of serious diseases, including breast cancer. Physical exercise training is an effective non-pharmacological strategy to improve health and quality of life in patients with breast cancer, mainly through positive effects on skeletal muscle mass, strength, and metabolic function. Emerging evidence has also highlighted the potential of exercise-induced crosstalk between skeletal muscle and cancer cells as one of the mechanisms controlling breast cancer progression. This intercellular communication seems to be mediated by a group of skeletal muscle molecules released in the bloodstream known as myokines. Among the myokines, exercise-induced circulating microRNAs (c-miRNAs) are deemed to mediate the antitumoral effects produced by exercise training through the control of key cellular processes, such as proliferation, metabolism, and signal transduction. However, there are still many open questions regarding the molecular basis of the exercise-induced effects on c-miRNA on human breast cancer cells. Here, we present evidence regarding the effect of exercise training on c-miRNA expression in breast cancer, along with the current gaps in the literature and future perspectives.

Stubborn Exercise Responders-Where to Next?

There is a wide variance in the magnitude of physiological adaptations after resistance or endurance training. The incidence of “non” or “poor” responders to training has been reported to represent as high as 40% of the project’s sample. However, the incidence of poor responders to training can be ameliorated with manipulation of either the training frequency, intensity, type and duration. Additionally, global non-response to cardio-respiratory fitness training is eliminated when evaluating several health measures beyond just the target variables as at least one or more measure improves. More research is required to determine if altering resistance training variables results in a more favourable response in individuals with an initial poor response to resistance training. Moreover, we recommend abandoning the term “poor” responders, as ultimately the magnitude of change in cardiorespiratory fitness in response to endurance training is similar in “poor” and “high” responders if the training frequency is subsequently increased. Therefore, we propose “stubborn” responders as a more appropriate term. Future research should focus on developing viable physiological and lifestyle screening tests that identify likely stubborn responders to conventional exercise training guidelines before the individual engages with training. Exerkines, DNA damage, metabolomic responses in blood, saliva and breath, gene sequence, gene expression and epigenetics are candidate biomarkers that warrant investigation into their relationship with trainability. Crucially, viable biomarker screening tests should show good construct validity to distinguish between different exercise loads, and possess excellent sensitivity and reliability. Furthermore “red flag” tests of likely poor responders to training should be practical to assess in clinical settings and be affordable and non-invasive. Early identification of stubborn responders would enable optimization of training programs from the onset of training to maintain exercise motivation and optimize the impact on training adaptations and health.

The effects of high-intensity functional training on cardiometabolic risk factors and exercise enjoyment in men and women with metabolic syndrome: study protocol for a randomized, 12-week, dose-response trial

Background

Individuals with metabolic syndrome (MetS) are at a greater risk for developing atherosclerotic cardiovascular disease (ASCVD) than those without MetS, due to underlying endothelial dysfunction, dyslipidemia, and insulin resistance. Exercise is an effective primary and secondary prevention strategy for MetS; however, less than 25% of adults meet the minimum stated public recommendations. Barriers often identified are lack of enjoyment and lack of time. High-intensity functional training (HIFT), a time-efficient modality of exercise, has shown some potential to elicit positive affectivity and elicit increased fitness and improved glucose metabolism. However, the effects of HIFT on dyslipidemia and endothelial dysfunction have not been explored nor have the effects been explored in a population with MetS. Additionally, no studies have investigated the minimal dose of HIFT per week to see clinically meaningful changes in cardiometabolic health. The purpose of this study is to (1) determine the dose-response effect of HIFT on blood lipids, insulin resistance, and endothelial function and (2) determine the dose-response effect of HIFT on body composition, fitness, and perceived enjoyment and intention to continue the exercise.

Methods/design

In this randomized, dose-response trial, participants will undergo a 12-week HIFT intervention of either 1 day/week, 2 days/week, or 3 days/week of supervised, progressive exercise. Outcomes assessed at baseline and post-intervention will be multiple cardiometabolic markers, and fitness. Additionally, the participant’s affective response will be measured after the intervention.

Discussion

The findings of this research will provide evidence on the minimal dose of HIFT per week to see clinically meaningful improvements in the risk factors of MetS, as well as whether this modality is likely to mitigate the barriers to exercise. If an effective dose of HIFT per week is determined and if this modality is perceived positively, it may provide exercise specialists and health care providers a tool to prevent and treat MetS.

Trial registration

ClinicalTrials.gov NCT05001126. August 11, 2021.

Resistance exercise as a treatment for sarcopenia: prescription and delivery

Sarcopenia is a generalised skeletal muscle disorder characterised by reduced muscle strength and mass and associated with a range of negative health outcomes. Currently, resistance exercise (RE) is recommended as the first-line treatment for counteracting the deleterious consequences of sarcopenia in older adults. However, whilst there is considerable evidence demonstrating that RE is an effective intervention for improving muscle strength and function in healthy older adults, much less is known about its benefits in older people living with sarcopenia. Furthermore, evidence for its optimal prescription and delivery is very limited and any potential benefits of RE are unlikely to be realised in the absence of an appropriate exercise dose. We provide a summary of the underlying principles of effective RE prescription (specificity, overload and progression) and discuss the main variables (training frequency, exercise selection, exercise intensity, exercise volume and rest periods) that can be manipulated when designing RE programmes. Following this, we propose that an RE programme that consists of two exercise sessions per week and involves a combination of upper- and lower-body exercises performed with a relatively high degree of effort for 1–3 sets of 6–12 repetitions is appropriate as a treatment for sarcopenia. The principles of RE prescription outlined here and the proposed RE programme presented in this paper provide a useful resource for clinicians and exercise practitioners treating older adults with sarcopenia and will also be of value to researchers for standardising approaches to RE interventions in future sarcopenia studies.

Whey Protein Supplementation Is Superior to Leucine-Matched Collagen Peptides to Increase Muscle Thickness During a 10-Week Resistance Training Program in Untrained Young Adults

The purpose of this study was to investigate the effects of supplementation of whey protein (WP) versus leucine-matched collagen peptides (CP) on muscle thickness MT and performance after a resistance training (RT) program in young adults. Twenty-two healthy untrained participants were randomly assigned to either a WP (n = 11) or leucine-matched CP (n = 11) group and then submitted to a supervised 10-week RT program (3 days/week). The groups were supplemented with an equivalent amount of WP (35 g, containing 3.0 g of leucine) and CP (35 g, containing 1.0 g of leucine and 2.0 g of free leucine) during the intervention period (after each workout and in the evening on nontraining days). MT of the vastus lateralis and biceps brachii, isokinetic peak torque and mean power output of the elbow flexors, and peak power output of the lower body were assessed before and after the RT program. The WP group experienced a greater (interaction, p < .05) increase in the vastus lateralis (effect size, WP = 0.68 vs. CP = 0.38; % Δ, WP = 8.4 ± 2.5 vs. CP = 5.6 ± 2.6%) and biceps brachii muscle thickness (effect size, WP = 0.61 vs. CP = 0.35; % , WP = 10.1 ± 3.8 vs. CP = 6.0 ± 3.2%), with a similar increase in muscle performance (peak torque, mean power output, and peak power output) between groups (time p < .05). Supplementation with WP was superior to leucine content-matched CP supplementation in increasing muscle size, but not strength and power, after a 10-week RT program in young adults.

Comprehensive Rehabilitation of the Athlete: A Specific and Purposeful Approach

There is a need to improve the quality of rehabilitation in sports medicine to return athletes to optimal function safely and quickly, reducing the risk of reinjury. This paper describes a planning paradigm to guide clinical reasoning during individual treatment sessions and a model for planning the rehabilitation program from acute injury to return to play. The design of a rehabilitation program should be a collaborative, team effort, and accounting for the specific needs of the athlete. As the athlete progresses from acute injury management all the way back to full competition, the rehabilitation professional emphasizes the components of pain management, motion, motor control, and force production in varying degrees based upon phases of tissue healing and the athlete's response. Utilizing high-value, evidence-based treatments maximize both the effectiveness and efficiency of rehabilitation to restore and improve upon preinjury levels of physical performance.

Minimal-Dose Resistance Training for Improving Muscle Mass, Strength, and Function: A Narrative Review of Current Evidence and Practical Considerations

Resistance training (RT) is the only non-pharmacological intervention known to consistently improve, and therefore offset age-related declines in, skeletal muscle mass, strength, and power. RT is also associated with various health benefits that are underappreciated compared with the perceived benefits of aerobic-based exercise. For example, RT participation is associated with reduced all-cause and cancer-related mortality and reduced incidence of cardiovascular disease, hypertension, and symptoms of both anxiety and depression. Despite these benefits, participation in RT remains low, likely due to numerous factors including time constraints, a high-perceived difficulty, and limited access to facilities and equipment. Identification of RT strategies that limit barriers to participation may increase engagement in RT and subsequently improve population health outcomes. Across the lifespan, declines in strength and power occur up to eight times faster than the loss of muscle mass, and are more strongly associated with functional impairments and risks of morbidity and mortality. Strategies to maximise healthspan should therefore arguably focus more on improving or maintaining muscle strength and power than on increasing muscle mass per se. Accumulating evidence suggests that minimal doses of RT, characterised by lower session volumes than in traditional RT guidelines, together with either (1) higher training intensities/loads performed at lower frequencies (i.e. low-volume, high-load RT) or (2) lower training intensities/loads performed at higher frequencies and with minimal-to-no equipment (i.e. resistance 'exercise snacking'), can improve strength and functional ability in younger and older adults. Such minimal-dose approaches to RT have the potential to minimise various barriers to participation, and may have positive implications for the feasibility and scalability of RT. In addition, brief but frequent minimal-dose RT approaches (i.e. resistance 'exercise snacking') may provide additional benefits for interrupting sedentary behaviour patterns associated with increased cardiometabolic risk. Compared to traditional approaches, minimal-dose RT may also limit negative affective responses, such as increased discomfort and lowered enjoyment, both of which are associated with higher training volumes and may negatively influence exercise adherence. A number of practical factors, including the selection of exercises that target major muscle groups and challenge both balance and the stabilising musculature, may influence the effectiveness of minimal-dose RT on outcomes such as improved independence and quality-of-life in older adults. This narrative review aims to summarise the evidence for minimal-dose RT as a strategy for preserving muscle strength and functional ability across the lifespan, and to discuss practical models and considerations for the application of minimal-dose RT approaches.

Effects of eccentric vs concentric cycling training on patients with moderate COPD

PURPOSE

The present study compared the effects of eccentric cycling (ECC) and conventional concentric cycling (CONC) training on muscle function, body composition, functional performance, and quality of life (QOL) of patients with moderate chronic obstructive pulmonary disease (COPD).

METHODS

Twenty patients (age: 69.6 ± 10.1 years, forced expiratory volume in 1-s: 73.2 ± 11.4% of predicted) were randomly allocated to ECC (n = 10) or CONC (n = 10) group. They performed 12 weeks of ECC or CONC training at similar perceived exertion. The workload, heart rate (HR), blood oxygen saturation (SpO₂), and dyspnea were monitored during cycling. Outcomes measures included maximal voluntary isometric contraction (MVC) strength of the knee extensors, rate of force development (RFD), lower limb fat-free (LLFFM) and fat (LLFM) mass, 6-min walking test (6MWT), timed up-and-go test (TUG), stairs ascending (SAWT) and descending walking time (SDWT), and QOL assessed by the Saint George's respiratory questionnaire.

RESULTS

ECC produced on average threefold greater (P < 0.001) workload (211.8 ± 106.0 kJ) than CONC (78.1 ± 62.6 kJ) over 34 training sessions. ECC showed 1.5 ± 2.1% greater SpO₂, 24.7 ± 4.1% lower HR, and 64.4 ± 29.6% lower dyspnea in average than CONC (P < 0.001). ECC increased LLFFM (4.5 ± 6.2%; P = 0.03), while CONC decreased LLFM (3.3 ± 6.4%; P = 0.04) after training. Both ECC and CONC reduced (P < 0.05) SAWT (- 16.1 ± 9.3% vs - 10.1 ± 14.4%) and SDWT (- 12.2 ± 12.6% vs - 14.4 ± 14.7%), and improved (P < 0.05) QOL (33.4 ± 38.8 vs 26.1 ± 36.6%) similarly, but only ECC improved (P < 0.05) RFD (69-199%), TUG (13.6 ± 13.6%), and 6MWT (25.3 ± 27.7%).

CONCLUSION

These results suggest that ECC training with less cardio-pulmonary demands was more effective in increasing functional performance and muscle mass for COPD patients than CONC training.

Time Course of Skeletal Muscle miRNA Expression after Resistance, High-Intensity Interval, and Concurrent Exercise

INTRODUCTION

Exercise-induced microRNA (miRNA) expression has been implicated in the regulation of skeletal muscle plasticity. However, the specificity and acute time course in miRNA expression after divergent exercise modes are unknown. In a randomized crossover design, we compared the acute expression profile of eight skeletal muscle miRNAs previously reported to be involved in skeletal muscle development, growth, and maintenance after a bout of either resistance exercise (RE), high-intensity interval exercise (HIIE), and concurrent resistance and high-intensity interval exercises (CE).

METHODS

Nine untrained young men (23.9 ± 2.8 yr, 70.1 ± 14.9 kg, 177.2 ± 3.0 cm, 41.4 ± 5.2 mL·kg-1·min-1) underwent a counterbalanced crossover design in which they performed bouts of RE (2 × 10 repetitions maximum 45° leg press and leg extension exercises), HIEE (12 × 1-min sprints at V˙O2peak with 1-min rest intervals between sprints), and CE (RE followed by HIIE), separated by 1 wk. Vastus lateralis biopsies were harvested immediately before (Pre) and immediately (0 h), 4 h, and 8 h after each exercise bout.

RESULTS

There were similar increases (main effect of time; P < 0.05) in miR-1-3p, miR-133a-3p, miR-133b, miR-181a-3p, and miR-486 expression at 8 h from Pre with all exercise modes. Besides a main effect of time, miR-23a-3p and miR-206 presented a main effect of condition with lower expression after HIIE compared with RE and CE.

CONCLUSIONS

Select miRNAs (miR-1-3p, miR-133a-3p, miR-133b, miR-23a-3p, miR-181a-3p, miR-206, miR-486) do not exhibit an expression specificity in the acute recovery period after a single bout of RE, HIIE, or CE in skeletal muscle. Our data also indicate that RE has a higher effect on the expression of miR-23a-3p and miR-206 than HIIE. As upregulation of these miRNAs seems to be confined to the 8-h period after exercise, this may subsequently affect the expression patterns of target mRNAs forming the basis of exercise-induced adaptive responses.

Resistance Exercise, Aging, Disuse, and Muscle Protein Metabolism

Skeletal muscle is the organ of locomotion, its optimal function is critical for athletic performance, and is also important for health due to its contribution to resting metabolic rate and as a site for glucose uptake and storage. Numerous endogenous and exogenous factors influence muscle mass. Much of what is currently known regarding muscle protein turnover is owed to the development and use of stable isotope tracers. Skeletal muscle mass is determined by the meal- and contraction-induced alterations of muscle protein synthesis and muscle protein breakdown. Increased loading as resistance training is the most potent nonpharmacological strategy by which skeletal muscle mass can be increased. Conversely, aging (sarcopenia) and muscle disuse lead to the development of anabolic resistance and contribute to the loss of skeletal muscle mass. Nascent omics-based technologies have significantly improved our understanding surrounding the regulation of skeletal muscle mass at the gene, transcript, and protein levels. Despite significant advances surrounding the mechanistic intricacies that underpin changes in skeletal muscle mass, these processes are complex, and more work is certainly needed. In this article, we provide an overview of the importance of skeletal muscle, describe the influence that resistance training, aging, and disuse exert on muscle protein turnover and the molecular regulatory processes that contribute to changes in muscle protein abundance. © 2021 American Physiological Society. Compr Physiol 11:2249-2278, 2021.

Personalized, Evidence-Informed Training Plans and Exercise Prescriptions for Performance, Fitness and Health

A training plan, or an exercise prescription, is the point where we translate sport and exercise science into practice. As in medicine, good practice requires writing a training plan or prescribing an exercise programme based on the best current scientific evidence. A key issue, however, is that a training plan or exercise prescription is typically a mix of many interacting interventions (e.g. exercises and nutritional recommendations) that additionally change over time due to periodisation or tapering. Thus, it is virtually impossible to base a complex long-term training plan fully on scientific evidence. We, therefore, speak of evidence-informed training plans and exercise prescriptions to highlight that only some of the underlying decisions are made using an evidence-based decision approach. Another challenge is that the adaptation to a given, e.g. endurance or resistance training programme is often highly variable. Until biomarkers for trainability are identified, we must therefore continue to test athletes, clients, or patients, and monitor training variables via a training log to determine whether an individual sufficiently responds to a training intervention or else re-plan. Based on these ideas, we propose a subjective, pragmatic six-step approach that details how to write a training plan or exercise prescription that is partially based on scientific evidence. Finally, we advocate an athlete, client and patient-centered approach whereby an individual’s needs and abilities are the main consideration behind all decision-making. This implies that sometimes the most effective form of training is eschewed if the athlete, client or patient has other wishes.

Individual Muscle Adaptations in different Resistance Training Systems in Well-Trained Men

Using a within-subject design we compared the individual responses between drop-set (DS) vs. traditional resistance training (TRAD) (n=16) and crescent pyramid (CP) vs. TRAD (n=15). Muscle cross-sectional area (CSA), leg press and leg extension 1 repetition maximum (1-RM) were assessed pre and post training. At group level, CSA increased from pre to post (DS: 7.8% vs. TRAD: 7.5%, P=0.02; CP: 7.5% vs. TRAD: 7.8%, P=0.02). All protocols increased the 1-RM from pre to post for leg press (DS: 24.9% vs. TRAD: 26.8%, P < 0.0001; CP: 27.3% vs. TRAD:2 6.3%, P < 0.0001) and leg extension (DS: 17.1% vs. TRAD: 17.3%, P < 0.0001; CP: 17.0% vs. TRAD: 16.6%, P < 0.0001). Individual analysis for CSA demonstrated no differences between protocols in 15 subjects. For leg press 1-RM, 5 subjects responded more to TRAD, 2 to DS and 9 similarly between protocols. In TRAD vs. CP, 4 subjects responded more to CP, 1 to TRAD and 10 similarly between protocols. For leg extension 1-RM 2 subjects responded more to DS, 3 to TRAD and 11 similarly between protocols. Additionally, 2 subjects responded more to CP, 2 to TRAD and 11 similarly between protocols. In conclusion, all protocols induced similar individual responses for CSA. For 1-RM, some subjects experience greater gains for the protocol performed with higher loads, such as CP.

Influence of resistance training load on measures of skeletal muscle hypertrophy and improvements in maximal strength and neuromuscular task performance: A systematic review and meta-analysis

This systematic review and meta-analysis determined resistance training (RT) load effects on various muscle hypertrophy, strength, and neuromuscular performance task [e.g., countermovement jump (CMJ)] outcomes. Relevent studies comparing higher-load [>60% 1-repetition maximum (RM) or <15-RM] and lower-load (≤60% 1-RM or ≥ 15-RM) RT were identified, with 45 studies (from 4713 total) included in the meta-analysis. Higher- and lower-load RT induced similar muscle hypertrophy at the whole-body (lean/fat-free mass; [ES (95% CI) = 0.05 (-0.20 to 0.29), P = 0.70]), whole-muscle [ES = 0.06 (-0.11 to 0.24), P = 0.47], and muscle fibre [ES = 0.29 (-0.09 to 0.66), P = 0.13] levels. Higher-load RT further improved 1-RM [ES = 0.34 (0.15 to 0.52), P = 0.0003] and isometric [ES = 0.41 (0.07 to 0.76), P = 0.02] strength. The superiority of higher-load RT on 1-RM strength was greater in younger [ES = 0.34 (0.12 to 0.55), P = 0.002] versus older [ES = 0.20 (-0.00 to 0.41), P = 0.05] participants. Higher- and lower-load RT therefore induce similar muscle hypertrophy (at multiple physiological levels), while higher-load RT elicits superior 1-RM and isometric strength. The influence of RT loads on neuromuscular task performance is however unclear.

The Impact of Coronavirus (COVID-19) Related Public-Health Measures on Training Behaviours of Individuals Previously Participating in Resistance Training: A Cross-Sectional Survey Study

Introduction

Understanding the impact of lockdown upon resistance training (RT), and how people adapted their RT behaviours, has implications for strategies to maintain engagement in similar positive health behaviours. Further, doing so will provide a baseline for investigation of the long-term effects of these public health measures upon behaviours and perceptions, and facilitate future follow-up study.

Objectives

To determine how the onset of coronavirus (COVID-19), and associated ‘lockdown’, affected RT behaviours, in addition to motivation, perceived effectiveness, enjoyment, and intent to continue, in those who regularly performed RT prior to the pandemic.

Methods

We conducted an observational, cross-sectional study using online surveys in multiple languages (English, Danish, French, German, Italian, Portuguese, Slovakian, Swedish, and Japanese) distributed across social media platforms and through authors’ professional and personal networks. Adults (n = 5389; median age = 31 years [interquartile range (IQR) = 25, 38]), previously engaged in RT prior to lockdown (median prior RT experience = 7 years [IQR = 4, 12]) participated. Outcomes were self-reported RT behaviours including: continuation of RT during lockdown, location of RT, purchase of specific equipment for RT, method of training, full-body or split routine, types of training, repetition ranges, exercise number, set volumes (per exercise and muscle group), weekly frequency of training, perception of effort, whether training was planned/recorded, time of day, and training goals. Secondary outcomes included motivation, perceived effectiveness, enjoyment, and intent to continue RT.

Results

A majority of individuals (82.8%) maintained participation in RT during-lockdown. Marginal probabilities from generalised linear models and generalised estimating equations for RT behaviours were largely similar from pre- to during-lockdown. There was reduced probability of training in privately owned gyms (~ 59% to ~ 7%) and increased probability of training at home (~ 18% to ~ 89%); greater probability of training using a full-body routine (~ 38% to ~ 51%); reduced probability of resistance machines (~ 66% to ~ 13%) and free weight use (~ 96% to ~ 81%), and increased probability of bodyweight training (~ 62% to ~ 82%); reduced probability of moderate repetition ranges (~ 62–82% to ~ 55–66%) and greater probability of higher repetition ranges (~ 27% to ~ 49%); and moderate reduction in the perception of effort experienced during-training (r = 0.31). Further, individuals were slightly less likely to plan or record training during lockdown and many changed their training goals. Additionally, perceived effectiveness, enjoyment, and likelihood of continuing current training were all lower during-lockdown.

Conclusions

Those engaged in RT prior to lockdown these behaviours with only slight adaptations in both location and types of training performed. However, people employed less effort, had lower motivation, and perceived training as less effective and enjoyable, reporting their likelihood of continuing current training was similar or lower than pre-lockdown. These results have implications for strategies to maintain engagement in positive health behaviours such as RT during-restrictive pandemic-related public health measures.

Pre-registration

https://osf.io/qcmpf.

Preprint

The preprint version of this work is available on SportRχiv: https://osf.io/preprints/sportrxiv/b8s7e/.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40279-021-01438-5.

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).

The Benefits of Strength Training on Musculoskeletal System Health: Practical Applications for Interdisciplinary Care

Global health organizations have provided recommendations regarding exercise for the general population. Strength training has been included in several position statements due to its multi-systemic benefits. In this narrative review, we examine the available literature, first explaining how specific mechanical loading is converted into positive cellular responses. Secondly, benefits related to specific musculoskeletal tissues are discussed, with practical applications and training programmes clearly outlined for both common musculoskeletal disorders and primary prevention strategies.

Relationships between physical capacities and biomechanical variables during movement tasks in athletic populations following anterior cruciate ligament reconstruction

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction has a detrimental impact on athletic performance. Despite rehabilitation guidelines and criterion-based progressions to ensure safe restoration of fundamental physical capacities and maladaptive movement strategies, residual deficits in maximal strength, rate of force development (RFD), power and reactive strength are commonly reported. These combined with associated compensatory inter and intra-limb strategies increase the risk of re-injury.

OBJECTIVE

The aim of this article is to examine the relationships between fundamental physical capacities and biomechanical variables during dynamic movement tasks.

DESIGN

Narrative review.

RESULTS

The available data suggests that quadriceps strength and rate of torque development, explain a moderate portion of the variance in aberrant kinetic and kinematic strategies commonly detected in ACL reconstructed cohorts in the later stages of rehabilitation and RTS CONCLUSION: The available data suggests that quadriceps strength and rate of torque development, explain a moderate portion of the variance in aberrant kinetic and kinematic strategies commonly detected in ACL reconstructed cohorts in the later stages of rehabilitation and RTS.

The Basics of Training for Muscle Size and Strength: A Brief Review on the Theory

The periodization of resistance exercise is often touted as the most effective strategy for optimizing muscle size and strength adaptations. This narrative persists despite a lack of experimental evidence to demonstrate its superiority. In addition, the general adaptation syndrome, which provides the theoretical framework underlying periodization, does not appear to provide a strong physiological rationale that periodization is necessary. Hans Selye conducted a series of rodent studies which used toxic stressors to facilitate the development of the general adaptation syndrome. To our knowledge, normal exercise in humans has never been shown to produce a general adaptation syndrome. We question whether there is any physiological rationale that a periodized training approach would facilitate greater adaptations compared with nonperiodized approaches employing progressive overload. The purpose of this article is to briefly review currently debated topics within strength and conditioning and provide some practical insight regarding the implications these reevaluations of the literature may have for resistance exercise and periodization. In addition, we provide some suggestions for the continued advancement within the field of strength and conditioning.

Effects of Pyramid Resistance-Training System with Different Repetition Zones on Cardiovascular Risk Factors in Older Women: A Randomized Controlled Trial

This study analyzed the effects of the pyramidal resistance training (RT) system with two repetition zones on cardiovascular risk factors in older women (≥60 years old). Fifty-nine older women were randomly assigned in three groups: non-exercise control (CON, n = 19), narrow-pyramid system (NPR, n = 20), and wide-pyramid system (WPR, n = 20). Training was performed for eight weeks (eight exercises for the whole-body, 3x/week) in which NPR and WPR performed three sets of 12/10/8 and 15/10/5 repetitions, respectively. Regional body fat was estimated by dual-energy X-ray absorptiometry, and blood parameters related to glycemic, lipid, and inflammatory profiles were assessed. After the training period, although no difference was observed for the magnitude of the changes between NPR and WPR, significant group by time interactions indicated benefits with RT compared to CON for reducing body fat (mainly android body fat; −7%) and improving glucose, HDL-C, LDL-C and C-reactive protein (p < 0.05). Composite z-score of cardiovascular risk, created by the average of the intervention effects on the outcomes, indicate similar responses between NPR and WPR, differing from CON (p < 0.001). Results indicate that both the repetition zones of the pyramidal RT reduced similarly the cardiovascular risk in older women.

Perceptual responses: Clinical versus practical blood flow restriction resistance exercise

The purpose of the current investigation was to compare the acute perceptual responses during low-load resistance exercise (RE) with clinical blood flow restriction (cBFR-RE) and practical blood flow restriction (pBFR-RE), and during conventional low- (LL-RE) and high-load resistance exercise (HL-RE), to determine if these responses differed between young males and females. Twenty-nine participants (14 males: 23.6±2.7years, 25.3±3.1kg/m² and 15 females: 20.3±1.6years, 23.4±1.9kg/m²) completed the following exercise conditions in a randomized design: 1) cBFR-RE, 2) pBFR-RE, 3) HL-RE, and 4) LL-RE. Low-load conditions consisted of 30-15-15-15 repetitions of two-leg press (LP) and knee extension (KE) exercises with 30% one-repetition maximum (1-RM), and HL-RE consisted of 3 sets of 10 repetitions at 80% 1-RM, all with 60s rest intervals. Ratings of perceived exertion (RPE) and discomfort were assessed before exercise and immediately following each set. RPE was significantly higher in HL-RE compared to all low-load conditions for both exercises after each set (all p<0.05). cBFR-RE resulted in significantly greater RPE than pBFR-RE and LL-RE for both exercises for sets 1-4 for LP and sets 2-3 for KE (all p<0.05). Levels of discomfort were similar between cBFR-RE and HL-RE, which tended to be significantly higher than pBFR-RE and LL-RE (p<0.05). Men reported significantly greater RPE than women following sets 2-4 during KE with cBFR-RE and sets 2 and 3 during KE for HL-RE (all p<0.05). Males also reported significantly greater discomfort than women following sets 2-4 for KE LL-RE (p<0.05). Altogether, these data suggest that pBFR-RE may provide a more favorable BFR condition based on perceptual responses and that perceptual responses may differ between sexes across varying resistance exercise conditions.

Do Older Adults With Reduced Bone Mineral Density Benefit From Strength Training? A Critically Appraised Topic

Clinical Scenario: Reduced bone mineral density (BMD) is a serious condition in older adults. The mild form, osteopenia, is often a precursor of osteoporosis. Osteoporosis is a pathological condition and a global health problem as it is one of the most common diseases in developed countries. Finding solutions for prevention and therapy should be prioritized. Therefore, the critically appraised topic focuses on strength training as a treatment to counteract a further decline in BMD in older adults. Clinical Question: Is strength training beneficial in increasing BMD in older people with osteopenia or osteoporosis? Summary of Key Findings: Four of the 5 reviewed studies with the highest evidence showed a significant increase in lumbar spine BMD after strength training interventions in comparison with control groups. The fifth study confirmed the maintenance of lumbar spine density due to conducted exercises. Moreover, 3 reviewed studies revealed increasing BMD at the femoral neck after strength training when compared with controls, which appeared significant in 2 of them. Clinical Bottom Line: The findings indicate that strength training has a significant positive influence on BMD in older women (ie, postmenopausal) with osteoporosis or osteopenia. However, it is not recommended to only rely on strength training as the increase of BMD may not appear fast enough to reach the minimal desired values. A combination of strength training and supplements/medication seems most adequate. Generalization of the findings to older men with reduced BMD should be done with caution due to the lack of studies. Strength of Recommendation: There is grade B of recommendation to support the validity of strength training for older women in postmenopausal phase with reduced BMD.

"NO LOAD" Resistance Training Promotes High Levels of Knee Extensor Muscles Activation-A Pilot Study

The present article aims to compare electromyographic (EMG) activity of the knee extensors during traditional resistance training (TRT) and no load resistance training with or without visual feedback (NL-VF and NL-NF). Sixteen healthy men (age: 25.2 ± 3.6) volunteered to participate in the study. Participants visited the laboratory on three occasions involving: (1) a 10 repetition maximum test (10 RM test), (2) familiarization and (3) performance of knee extensions using TRT, NL-VF and NL-NF in a random order, with 10 min of rest between them. TRT involved the performance of a set to momentary muscle failure using the 10 RM load. NL-NF involved the performance of 10 repetitions with no external load, but with the intention to maximally contract the muscles during the whole set. NL-VF involved the same procedure as NL-NF, but a monitor was positioned in front of the participants to provide visual feedback on the EMG activity. Peak and mean EMG activity were evaluated on the vastus medialis (VM), vastus lateralis (VL) and rectus femoris (RF). Results: there were no significant differences in VM and VL peak EMG activity among different situations. There was a significant difference for peak EMG activity for RF, where TRT resulted in higher values than NL-VF and NL-NF (p < 0.05). Higher values of mean EMG activity were found for VM, VL and RF during TRT in comparison with both NL-VF and NL-NF. Conclusions: resistance training with no external load produced high levels of peak muscle activation, independent of visual feedback, but mean activation was higher during TRT. These results suggest that training with no external load might be used as a strategy for stimulating the knee extensors when there is limited access to specialized equipment. Although the clinical applications of no load resistance training are promising, it is important to perform long-term studies to test if these acute results will reflect in muscle morphological and functional changes.

The Effects of Concurrent Training Combining Both Resistance Exercise and High-Intensity Interval Training or Moderate-Intensity Continuous Training on Metabolic Syndrome

To date, there are several knowledge gaps on how to properly prescribe concurrent training to achieve the best dose-response, especially regarding the optimal intensity or volume of the aerobic component. Thus, the objective of this study is to analyze the effects of different aerobic exercise modes and intensities [i.e. aerobic high-intensity interval training (HIIT) versus moderate-intensity continuous aerobic training (MICT) combined with a resistance training (RT) program] on metabolic outcomes in participants with metabolic syndrome (MetS). Thirty-nine men and women (67.0 ± 6.7 years) volunteered to a 12-weeks exercise intervention (3 week^–1, 50 min/session) and were randomly assigned to one of three groups: (a) RT plus MICT (RT+MICT) (2 males; 11 females); (b) RT plus HIIT (RT+HIIT) (4 males; 9 females); and (c) control group (CON) – without formal exercise (4 males; 9 females). Intensity was established between 60 and 70% of maximum heart rate (HRmax) in RT+MICT and ranged from 55–65% to 80–90% HRmax in the RT+HIIT group. Dependent outcomes included morphological, metabolic and hemodynamic variables. Both training groups improved waist circumference (RT+MICT: P = 0.019; RT+HIIT: P = 0.003), but not body weight, fat mass or fat-free mass (P ≥ 0.114). RT+HIIT group improved fasting glucose (P = 0.014), low density lipoprotein [LDL (P = 0.022)], insulin (P = 0.034) and homeostatic model assessment (P = 0.028). RT+MICT group reduced triglycerides (P = 0.053). Both exercise interventions did not change high sensitivity C-reactive protein, glycated hemoglobin, high density lipoprotein and total cholesterol, systolic, diastolic or mean arterial blood pressure (P ≥ 0.05). The CON group reduced the LDL (P = 0.031). This trial suggests that short-term exercise mode and intensity may differently impact the metabolic profile of individuals with MetS. Further, our data suggests that both concurrent trainings promote important cardiometabolic gains, particularly in the RT+HIIT. Nonetheless, due to the small-to-moderate effect size and the short-term intervention length, our data suggests that the intervention length also has an important modulating role in these benefits in older adults with MetS. Therefore, more research is needed to confirm our results using longer exercise interventions and larger groups.

Recent advances in understanding resistance exercise training-induced skeletal muscle hypertrophy in humans

Skeletal muscle plays a pivotal role in the maintenance of physical and metabolic health and, critically, mobility. Accordingly, strategies focused on increasing the quality and quantity of skeletal muscle are relevant, and resistance exercise is foundational to the process of functional hypertrophy. Much of our current understanding of skeletal muscle hypertrophy can be attributed to the development and utilization of stable isotopically labeled tracers. We know that resistance exercise and sufficient protein intake act synergistically and provide the most effective stimuli to enhance skeletal muscle mass; however, the molecular intricacies that underpin the tremendous response variability to resistance exercise-induced hypertrophy are complex. The purpose of this review is to discuss recent studies with the aim of shedding light on key regulatory mechanisms that dictate hypertrophic gains in skeletal muscle mass. We also aim to provide a brief up-to-date summary of the recent advances in our understanding of skeletal muscle hypertrophy in response to resistance training in humans.

Eccentric, but not concentric blood flow restriction resistance training increases muscle strength in the untrained limb

OBJECTIVES

Little is known regarding the variables or mechanisms mediating cross-education as a result of resistance training. Therefore, the purpose of the present study was to examine the effects of low-load eccentric-only blood flow restriction (Ecc-BFR) and low-load concentric-only BFR (Con-BFR) on indices of cross-education.

DESIGN

Thirty-six women were randomly assigned to 4-wks of unilateral resistance training with Ecc-BFR (n = 12), Con-BFR (n = 12) or control (no intervention, n = 12) group. Eccentric peak torque, concentric peak torque, maximal voluntary isometric contraction torque, muscle thickness, and muscle activation were assessed from the contralateral, untrained arm.

RESULTS

Muscle strength (collapsed across mode) increased from 0-wk to 2-wks (4.9%) and 4-wks (13.0%) for Ecc-BFR only. There were increases in muscle activation (collapsed across mode and group) regardless of training modality, but there were no changes in muscle size for any of the conditions.

CONCLUSIONS

The findings of the present study indicated that low-load Ecc-BFR increased muscle strength. The increases in muscle strength as a result of Ecc-BFR were not mode-specific. Thus, low-load Ecc-BFR provides a unique alternative to maintain muscle function in an untrained limb that may have application during limb immobilization and rehabilitation practices.

Functional and/or structural brain changes in response to resistance exercises and resistance training lead to cognitive improvements - a systematic review

BACKGROUND

During the aging process, physical capabilities (e.g., muscular strength) and cognitive functions (e.g., memory) gradually decrease. Regarding cognitive functions, substantial functional (e.g., compensatory brain activity) and structural changes (e.g., shrinking of the hippocampus) in the brain cause this decline. Notably, growing evidence points towards a relationship between cognition and measures of muscular strength and muscle mass. Based on this emerging evidence, resistance exercises and/or resistance training, which contributes to the preservation and augmentation of muscular strength and muscle mass, may trigger beneficial neurobiological processes and could be crucial for healthy aging that includes preservation of the brain and cognition. Compared with the multitude of studies that have investigated the influence of endurance exercises and/or endurance training on cognitive performance and brain structure, considerably less work has focused on the effects of resistance exercises and/or resistance training. While the available evidence regarding resistance exercise-induced changes in cognitive functions is pooled, the underlying neurobiological processes, such as functional and structural brain changes, have yet to be summarized. Hence, the purpose of this systematic review is to provide an overview of resistance exercise-induced functional and/or structural brain changes that are related to cognitive functions.

METHODS AND RESULTS

A systematic literature search was conducted by two independent researchers across six electronic databases; 5957 records were returned, of which 18 were considered relevant and were analyzed.

SHORT CONCLUSION

Based on our analyses, resistance exercises and resistance training evoked substantial functional brain changes, especially in the frontal lobe, which were accompanied by improvements in executive functions. Furthermore, resistance training led to lower white matter atrophy and smaller white matter lesion volumes. However, based on the relatively small number of studies available, the findings should be interpreted cautiously. Hence, future studies are required to investigate the underlying neurobiological mechanisms and to verify whether the positive findings can be confirmed and transferred to other needy cohorts, such as older adults with dementia, sarcopenia and/or dynapenia.