Different response to eccentric and concentric training in older men and women

Eccentric and concentric exercises induce different adaptions in adipose tissue biology

Alterations in adipose tissue (AT) metabolism related to inflammation and adipokine's production lead to perturbations in its capacity to store lipids and release fatty acids (FA) during feeding/fasting transition or during exercise. Exercise has a beneficial effect on AT metabolism, but conventional trainings are not always suitable for patients with functional limitations. Dynamic eccentric (ECC) exercise prevents the accumulation of AT and may then overcome those limitations. Consequently, this study aimed at investigating AT's adaptations after ECC training. Nine-week-old male rats were randomly assigned to a control sedentary or three-trained groups for which treadmill slopes modulated exercise oxygen consumption (VO₂) and mechanical work (n = 15 per group): (1) + 15% uphill-concentric group (CONC), (2) - 15% downhill group (ECC15, same mechanical work as CONC) and (3) - 30% downhill group (ECC30, same VO₂, or oxygen cost as CONC). Body composition and energy expenditure (EE) were measured before and after 8 weeks of training. Subcutaneous AT was collected to study total FA profile and gene expression. Higher total EE was driven by lean mass gain in trained animals. In AT, there was a decrease in arachidonic acid with CONC or ECC15 training. Increased adiponectin, leptin, lipases, Glut4 and Igf1 mRNA levels in ECC15 group suggested major metabolic adaption in AT. In conclusion, ECC could induce beneficial modifications in AT fatty acid profile and the expression of key genes related to metabolism and insulin sensitivity.

Benefits of Eccentric Training with Emphasis on Demands of Daily Living Activities and Feasibility in Older Adults: A Literature Review

Aging is associated with a decline in physical capabilities and several other health-related conditions. One of the most common age-related processes is sarcopenia. Sarcopenia is usually accompanied with a decline in skeletal muscle mass and physical functioning. A decrease in these markers usually impacts basic daily living activities (DLAs), which become somewhat harder to accomplish for older individuals. Several research studies have examined the demands of DLA in older individuals with results indicating that activities such as walking, sitting, standing, stair climbing, stair descending, and running generate high demands on older adults. The forces that act on individuals are in most cases equal or multiple times higher relative to their body mass. For instance, it was reported that the GRF (ground reaction force) during stair descent ranged from 1.43 to 1.50 of BW (body weight) in an older population. Even higher demands were recorded during other related activities. These demands of DLA raise the question of appropriate rehabilitative or training management procedures. During the past decades, an eccentric form of resistance training gained popularity due to its effectiveness and lower metabolic demands, which seems to be an appropriate method to develop and maintain a basic level of strength capabilities in higher age. Multiple factors of eccentric training have been examined including modality of exercise, intensity, frequency, and safety of the elderly. Several modalities of eccentric exercise have been shown to be effective including traditional methods, as well as machine-based ones, with or without using some equipment. The studies included in this review varied in intensity from low to high; however, the most frequently used intensity was ≥50% of the maximal eccentric strength during two or three eccentric sessions per week. Importantly, the prevalence of injury of older adults appears to have been low to none, highlighting the safety of this approach. In summary, eccentric training prescriptions for older adults should consider the demands of DLA and the characteristics of the elderly for appropriate management of training recommendations.

Chronic Adaptations to Eccentric Cycling Training: A Systematic Review and Meta-Analysis

This study aimed to investigate the effects of eccentric cycling (ECCCYC) training on performance, physiological, and morphological parameters in comparison to concentric cycling (CONCYC) training. Searches were conducted using PubMed, Embase, and ScienceDirect. Studies comparing the effect of ECCCYC and CONCYC training regimens on performance, physiological, and/or morphological parameters were included. Bayesian multilevel meta-analysis models were used to estimate the population's mean difference between chronic responses from ECCCYC and CONCYC training protocols. Group levels and meta-regression were used to evaluate the specific effects of subjects and study characteristics. Fourteen studies were included in this review. The meta-analyses showed that ECCCYC training was more effective in increasing knee extensor strength, vastus lateralis fiber cross-sectional area, and six-minute walking distance compared to CONCYC. Moreover, ECCCYC was as effective as CONCYC in decreasing body fat percentage. CONCYC was more effective in increasing V˙O2max and peak power output attained during concentric incremental tests. However, group-level analyses revealed that ECCCYC was more effective than CONCYC in improving V˙O2max in patients with cardiopulmonary diseases. ECCCYC is a viable modality for exercise interventions aiming to improve parameters of muscle strength, hypertrophy, functional capacity, aerobic power, and body composition, with more advantages than CONCYC training in improving neuromuscular variables.

Reliability and Variability of Lower Limb Muscle Activation as Indicators of Familiarity to Submaximal Eccentric Cycling

Submaximal eccentric (ECC) cycling exercise is commonly used in research studies. No previous study has specified the required time naïve participants take to familiarize with submaximal ECC cycling. Therefore, we designed this study to determine whether critical indicators of cycling reliability and variability stabilize during 15 min of submaximal, semi-recumbent ECC cycling (ECC cycling). Twenty-two participants, aged between 18–51 years, volunteered to complete a single experimental session. Each participant completed three peak eccentric torque protocol (PETP) tests, nine countermovement jumps and 15 min of submaximal (i.e., 10% peak power output produced during the PETP tests) ECC cycling. Muscle activation patterns were recorded from six muscles (rectus femoris, RF; vastus lateralis, VL; vastus medialis, VM; soleus, SOL; medial gastrocnemius, GM; tibialis anterior, TA), during prescribed-intensity ECC cycling, using electromyography (EMG). Minute-to-minute changes in the reliability and variability of EMG patterns were examined using intra-class correlation coefficient (ICC) and variance ratios (VR). Differences between target and actual power output were also used as an indicator of familiarization. Activation patterns for 4/6 muscles (RF, VL, VM and GM) became more consistent over the session, the RF, VL and VM increasing from moderate (ICC = 0.5–0.75) to good (ICC = 0.75–0.9) reliability by the 11th minute of cycling and the GM good reliability from the 1st minute (ICC = 0.79, ICC range = 0.70–0.88). Low variability (VR ≤ 0.40) was maintained for VL, VM and GM from the 8th, 8th and 1st minutes, respectively. We also observed a significant decrease in the difference between actual and target power output (χ214 = 30.895, p = 0.006, W = 0.105), expressed primarily between the 2nd and 3rd minute of cycling (Z = -2.677, p = 0.007). Indicators of familiarization during ECC cycling, including deviations from target power output levels and the reliability and variability of muscle activation patterns stabilized within 15 min of cycling. Based upon this data, it would be reasonable for future studies to allocate ∼ 15 min to familiarize naïve participants with a submaximal ECC cycling protocol.

The Effect of Eccentric vs. Traditional Resistance Exercise on Muscle Strength, Body Composition, and Functional Performance in Older Adults: A Systematic Review With Meta-Analysis

The effects of eccentric exercise (ECC) in older adults have received limited scientific attention, considering the ample evidence for its effectiveness in general and athletic populations. The purpose of this paper is to review the effects of ECC exercise modalities vs. traditional or concentric (CON) exercise on muscle strength, body composition and functional performance in older adults. Inclusion criteria regarding the age was >55 years. Three major scientific literature databases (PubMed, Scopus and Web of Science) were screened for trials comparing the effect of ECC and CON exercise programs, and 19 papers were included in the meta-analysis. ECC and CON training programs were typically matched by the duration of each session. The difference between ECC and CON was expressed as standardized mean difference (SMD). Regarding isometric knee strength, the pooled effect favored ECC (SMD = 0.50), but was not statistically significant (p = 0.160). ECC exercise elicited greater improvements in timed up and go test (SMD = −0.68; p = 0.004), 2-min sit-stand test (SMD = 0.53; p = 0.030) and 30-s sit-stand test (SMD = 0.81; p = 0.002), but not in 6-min walking test (SMD = 0.01; p = 0.960). The effects on body composition and muscle architecture were unclear (SMD = −1.44 to 1.95; p = 0.060–0.689). In conclusion, our literature review indicates that ECC exercise is superior to, or at least as good as CON exercise for preserving health and overall function in older adults.

Flywheel Training in Older Adults—A Systematic Review

The process of healthy aging might be reconsidered, based on the nonfatal outcomes of falls in older adults. Flywheel training is a relatively new training method used by different age groups, which enables the muscles to contract at maximum force in minimum time. The study aim was to summarize the relevant literature about the effects of flywheel training in older adults and to determine its efficiency and feasibility. PRISMA guidelines were followed for both the search and analysis. Electronic databases (Google Scholar, PubMed, Science Direct, Scopus, Web of Science and SPORTDiscuss) yielded 9915 studies, but we have included studies published in English between 2005 and 2021, cross-sectional and pre-post treatments, with older adults (≥60 years) as the sample, where flywheel training was conducted. A total of nine studies have met the pre-defined criteria and entered the systematic review, with a total of 216 participants, both male and female. After analyzing the obtained results, it can be concluded that flywheel training showed physical, neuromuscular, and functional improvements in older adults. However, the review did not reveal an optimal duration, frequency, intensity, or volume. Furthermore, it can be stated that this training method can be considered as an appropriate form of activity in older adults, as a tool for improving overall health.

Effect of Application of Repeated Downhill Walking Bouts on Ankle Isokinetic Parameters in Children with Obesity

BACKGROUND

Obesity among children became of high concern. Obesity can affect many health aspects including muscular strength. Downhill walking is a useful intervention to enhance muscular strength, especially in older adults.

OBJECTIVE

The current study's purpose was to investigate the effect of repeated bouts of downhill walking on ankle isokinetic parameters in children with obesity.

METHODS

32 obese male children aged from 8 to 12 years engaged in the study. The children were divided into two groups: the level walking group (LWG) (n = 16) and the downhill walking group (DWG) (n = 16). Participants in both groups walked 20 minutes on the treadmill, two sessions per week for 6 weeks, with a speed of 5 km/h, and the treadmill slope used for the DWG was set at -20%. Isokinetic dynamometry (Cybex 6000) was used to analyze the normalized eccentric and concentric torque of both ankle dorsiflexors and plantar flexors of the dominant leg in all participants.

RESULTS

The normalized peak torques for eccentric plantar flexion, concentric plantar flexion, eccentric dorsiflexion, and concentric dorsiflexion significantly increased by 38.66%, 23.87%, 38.58%, and 15.51%, respectively, after repeated bouts of downhill walking. Level walking resulted in nonsignificant improvement in the muscular torques.

CONCLUSION

Downhill walking is a beneficial intervention in improving ankle muscular torques of obese children.

Applications of Eccentric Exercise to Improve Muscle and Mobility Function in Older Adults

Muscle aging ultimately leads to the deterioration of human physiological functioning, including declining muscle strength, loss of muscle mass, and decreased quality of life in advanced age. Eccentric exercise is a key intervention that has the potential to ameliorate this problem. Recent studies have focused on evidence-based exercise interventions to prevent declines in muscle strength and physical function in older adults. This paper reviewed relevant literature on the use of eccentric exercise to improve muscle and mobility function in older adults. We explained not only the changes in mobility that occur with aging but also the rationale for and positive effects of eccentric intervention in older adults. We also explored several proposed mechanisms for the intramuscular changes caused by eccentric muscle contraction and considered the safety and side effects accompanying eccentric training. We concluded by suggesting that eccentric exercise is an exercise modality that can potentially improve muscle strength and enhance mobility in older adults.

Improved Muscle Strength, Muscle Power, and Physical Function After Flywheel Resistance Training in Healthy Older Adults: A Randomized Controlled Trial

ABSTRACT

Sañudo, B, de Hoyo, M, and McVeigh, JG. Improved muscle strength, muscle power, and physical function after flywheel resistance training in healthy older adults: A randomized controlled trial. J Strength Cond Res 36(1): 252-258, 2022-This study aimed to examine whether flywheel resistance exercise training improved muscle strength, muscle power, and physical function in older adults. Thirty-six older adults (64 ± 5 years) were randomly allocated to either a flywheel resistance exercise training group (ETG; n = 18) or a control (CON) group (n = 18). Subjects in the ETG underwent 6 weeks of resistance training on a flywheel squat device (4 sets of 9 maximal repetitions). Isokinetic concentric (60 and 240°·s-1) and eccentric (120°·s-1) knee extension and flexion peak torques and mean power were measured. Physical function was assessed by the 30-second Chair Sit-Stand Test (CST) and walking speed. After the intervention, within-group analyses showed significantly greater flexion torques and mean power with the dominant leg (concentric at 60°·s-1 and 240°·s-1 and eccentric at 120°·s-1; all d > 0.7, p < 0.05) and improvements in CST (d > 0.8) in the ETG, while no substantial differences were found in the CON group. Significant between-group differences in knee flexion torque both concentric (at 60°·s-1: η2 = 0.168 and 240°·s-1: η2 = 0.112) and eccentric (at 120°·s-1: η2 = 0.103) with the dominant leg were also found in favor of the ETG. There was also significantly better performance in the CST for the ETG (η2 = 0.207). There was a significant association between changes in strength and changes in mean power in the ETG. Changes in physical function outcomes were also observed. In conclusion, flywheel resistance exercise training is an appropriate form of activity for improving strength and functional capacity of older adults.

Eccentric-only versus concentric-only resistance training effects on biochemical and physiological parameters in patients with type 2 diabetes

Background

The benefits of resistance training for patients with type 2 diabetes (T2D) are well documented; however, the effects of exercise with different muscle contraction types such as eccentric versus concentric contractions on physiological outcomes for this population are not clear. This study compared eccentric-only (ECC) and concentric-only resistance training (CON) to test the hypothesis that ECC would be superior to CON to improve insulin sensitivity, lipid profile, body composition, muscle strength and physical function of patients with T2D.

Methods

Adults with T2D (50–79 years) were allocated to the ECC (n = 9) or CON group (n = 9). Resistance exercises (chest press, lateral pulldown, bicep curl, triceps extension, leg extension, leg curl, calf raise, abdominal crunch) consisting of 2–3 sets of 10 eccentric-only (5 s) or concentric-only contractions (1–2 s) was performed twice a week for 12 weeks. Changes in blood biomarkers, body composition, muscle strength and physical function from pre- to post-intervention were compared between groups.

Results

Overall rating of perceived exertion (RPE, 1–10 Borg scale) was lower (p < 0.05) for ECC (2.9 ± 1.2) than CON (5.4 ± 1.1). No significant changes in blood biomarkers were found for both groups. Lean mass increased [effect size (ES) = 0.148, ECC 3.2 ± 6.9%; CON 3.6 ± 2.3%], and fat mass decreased (ES = 0.545, ECC − 6.1 ± 12.4%; CON − 7.1 ± 16.4%) (p < 0.05) similarly. One-repetition maximal strength of each exercise increased (p < 0.05) for both ECC (12–37%) and CON (27–68%). Both groups improved (p < 0.05) 6-min walk distance (ES = 0.083, ECC 12.2 ± 2.3%; CON 12.5 ± 15.3%) and chair rise time (ES = 0.463, ECC − 13.4 ± 25.4%; CON − 20.0 ± 53.3%) but only ECC improved (p < 0.05) the timed up-and-go test (− 11.3 ± 13.6%, ES 0.014). No significant changes in balance tests were found for both groups.

Conclusion

These results did not fully support the hypothesis but showed that ECC was as effective as CON to improve body composition, muscle strength, and physical function with lesser RPE. Future studies should investigate whether larger differences between ECC and CON are evident when increasing the exercise frequency and matching the intensities of the two-exercise protocols.

Trial registration ACTRN12621001026819 (retrospectively registered on 5th Aug 2021).

Potential Benefits of a Minimal Dose Eccentric Resistance Training Paradigm to Combat Sarcopenia and Age-Related Muscle and Physical Function Deficits in Older Adults

The ability of older adults to perform activities of daily living is often limited by the ability to generate high mechanical outputs. Therefore, assessing and developing maximal neuromuscular capacity is essential for determining age-related risk for functional decline as well as the effectiveness of therapeutic interventions. Interventions designed to enhance neuromuscular capacities underpinning maximal mechanical outputs could positively impact functional performance in daily life. Unfortunately, < 10% of older adults meet the current resistance training guidelines. It has recently been proposed that a more “minimal dose” RT model may help engage a greater proportion of older adults, so that they may realize the benefits of RT. Eccentric exercise offers some promising qualities for such an approach due to its efficiency in overloading contractions that can induce substantial neuromuscular adaptations. When used in a minimal dose RT paradigm, eccentric-based RT may be a particularly promising approach for older adults that can efficiently improve muscle mass, strength, and functional performance. One approach that may lead to improved neuromuscular function capacities and overall health is through heightened exercise tolerance which would favor greater exercise participation in older adult populations. Therefore, our perspective article will discuss the implications of using a minimal dose, submaximal (i.e., low intensity) multi-joint eccentric resistance training paradigm as a potentially effective, and yet currently underutilized, means to efficiently improve neuromuscular capacities and function for older adults.

Effectiveness of eccentric-biased exercise interventions in reducing the incidence of falls and improving functional performance in older adults: a systematic review

Aim

To systematically review the literature on the effectiveness of eccentric exercise interventions in reducing falls and improving the functional performance in older adults.

Findings

The existing literature was of mixed quality and suggested that eccentric exercises can be as effective as conventional exercises in improving functional performance in healthy older adults. There was limited evidence focussing on the aspect of incidence of falls.

Message

Eccentric exercises may be as effective as conventional exercises in improving geriatric function, although evidence remains limited. More research is needed to explore any adverse effects of such exercises in older adults.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41999-021-00571-8.

Background

Exercise has been known to preserve and enhance functional performance in older adults. Eccentric exercise involves muscle contractions characterised by unique features such as lengthening of the muscle–tendon complex by a greater opposing force.

Aims

To systematically review randomised-controlled trials (RCTs) investigating the effectiveness of eccentric exercises in reducing the incidence of falls and improving the functional performance in older adults.

Key methods

We conducted a systematic review of RCTs following the PRISMA-P guidelines. Searches were completed in the Cochrane Central Register of Controlled Trials, Embase, CINAHL, Medline, and Global Health CABI. We included RCTs reporting at least one of the following outcomes—falls, Berg balance scale, timed-up and go test, chair stand test, stair climb test, maximal walking speed, and minute walking distance. Two reviewers screened papers for eligibility and assessed the quality of included papers using the Cochrane Collaborative risk-of-bias tool for randomised trials. Data were extracted by a single reviewer and cross-checked by the second reviewer. A narrative synthesis was undertaken, given the high level of heterogeneity across studies.

Results

Ten studies were assessed as eligible for inclusion in the review. Overall, eccentric exercises were as effective as conventional resistance exercises in improving the selected outcomes by most studies. Additionally, when pre-exercise and post-eccentric exercise functional performance measures were compared, there was a statistically significant improvement in nearly all measures. The quality of trials was mixed (one high, four moderate, two low–moderate, and three low risk of bias).

Conclusions

Our systematic review suggests that eccentric exercises can be as effective as conventional exercises in older adults. Evidence suggests that such exercise interventions can lead to an improvement in geriatric function.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41999-021-00571-8.

Effects of physical exercise in sarcopenia. A systematic review

From the third decade of life and due to multiple causes, muscle mass and strength are gradually lost, which affects the function of the musculoskeletal system. This combined loss of muscle mass and strength with aging is called sarcopenia, and is associated with greater morbidity and mortality in the elderly. Early treatment is therefore essential, and physical exercise is the therapeutic approach that has given the best results. This literature review intended to analyze the effect of physical exercise, excluding the role that other treatments proposed, including the nutritional approach, could play in the treatment of sarcopenia, refers to 12 articles. In studies including high intensity strength exercises in isolation, either alone or combined with aerobic exercise, improvements were seen in muscle mass, muscle strength, and functional test times. There is also a significant increase in fat-free mass in individuals who exercised more frequently (more than two sessions per week). Current evidence shows that strength-resistance training and its combination in multimodal programs with aerobic exercise show significantly beneficial effects on anthropometric and muscle function parameters. Programs of prescribed exercises including strength exercises adequate to the characteristics should therefore be adapted to the characteristics of each individual and replace the usual practice of prescribing aerobic exercises (walking) only.

Can Exercise-Induced Muscle Damage Be a Good Model for the Investigation of the Anti-Inflammatory Properties of Diet in Humans?

Subclinical, low-grade, inflammation is one of the main pathophysiological mechanisms underlying the majority of chronic and non-communicable diseases. Several methodological approaches have been applied for the assessment of the anti-inflammatory properties of nutrition, however, their impact in human body remains uncertain, because of the fact that the majority of the studies reporting anti-inflammatory effect of dietary patterns, have been performed under laboratory settings and/or in animal models. Thus, the extrapolation of these results to humans is risky. It is therefore obvious that the development of an inflammatory model in humans, by which we could induce inflammatory responses to humans in a regulated, specific, and non-harmful way, could greatly facilitate the estimation of the anti-inflammatory properties of diet in a more physiological way and mechanistically relevant way. We believe that exercise-induced muscle damage (EIMD) could serve as such a model, either in studies investigating the homeostatic responses of individuals under inflammatory stimuli or for the estimation of the anti-inflammatory or pro-inflammatory potential of dietary patterns, foods, supplements, nutrients, or phytochemicals. Thus, in this review we discuss the possibility of exercise-induced muscle damage being an inflammation model suitable for the assessment of the anti-inflammatory properties of diet in humans.

Delayed Impairment of Postural, Physical, and Muscular Functions Following Downhill Compared to Level Walking in Older People

Transient symptoms of muscle damage emanating from unaccustomed eccentric exercise can adversely affect muscle function and potentially increase the risk of falling for several days. Therefore, the aims of the present study were to investigate the shorter- and longer-lasting temporal characteristics of muscle fatigue and damage induced by level (i.e., concentrically biased contractions) or downhill (i.e., eccentrically biased contractions) walking on postural, physical, and muscular functions in older people. Nineteen participants were matched in pairs for sex, age and self-selected walking speed and allocated to a level (n = 10, age = 72.3 ± 2.9 years) or downhill (n = 9, age = 72.1 ± 2.2 years) walking group. Postural sway, muscle torque and power, physical function (5× and 60 s sit-to-stand; STS), and mobility (Timed-Up-and-Go; TUG) were evaluated at baseline (pre-exercise), 1 min, 15 min, 30 min, 24 h, and 48 h after 30 min of level (0% gradient) or downhill (−10% gradient) walking on a treadmill. Following downhill walking, postural sway (+66 to 256%), TUG (+29%), 60 s STS (+29%), five times STS (−25%) and concentric power (−33%) did not change at 1–30 min post exercise, but were significantly different (p < 0.05) at 24 and48 h post-exercise when compared to baseline (p < 0.05). Muscle torque decreased immediately after downhill walking and remained impaired at 48 h post-exercise (−27 to −38%). Immediately following level walking there was an increase in postural sway (+52 to +98%), slower TUG performance (+29%), fewer STS cycles in 60 s (−23%), slower time to reach five STS cycles (+20%) and impaired muscle torque (−23%) and power (−19%) which returned to baseline 30-min after exercise cessation (p > 0.05). These findings have established for the first time distinct impairment profiles between concentric and eccentric exercise. Muscle damage emanating from eccentrically biased exercise can lead to muscle weakness, postural instability and impaired physical function persisting for several days, possibly endangering older adult’s safety during activities of daily living by increasing the risk of falls.

Moving forward with backward pedaling: a review on eccentric cycling

PURPOSE

There is a profound gap in the understanding of the eccentric cycling intensity continuum, which prevents accurate exercise prescription based on desired physiological responses. This may underestimate the applicability of eccentric cycling for different training purposes. Thus, we aimed to summarize recent research findings and screen for possible new approaches in the prescription and investigation of eccentric cycling.

METHOD

A search for the most relevant and state-of-the-art literature on eccentric cycling was conducted on the PubMed database. Literature from reference lists was also included when relevant.

RESULTS

Transversal studies present comparisons between physiological responses to eccentric and concentric cycling, performed at the same absolute power output or metabolic load. Longitudinal studies evaluate responses to eccentric cycling training by comparing them with concentric cycling and resistance training outcomes. Only one study investigated maximal eccentric cycling capacity and there are no investigations on physiological thresholds and/or exercise intensity domains during eccentric cycling. No study investigated different protocols of eccentric cycling training and the chronic effects of different load configurations.

CONCLUSION

Describing physiological responses to eccentric cycling based on its maximal exercise capacity may be a better way to understand it. The available evidence indicates that clinical populations may benefit from improvements in aerobic power/capacity, exercise tolerance, strength and muscle mass, while healthy and trained individuals may require different eccentric cycling training approaches to benefit from similar improvements. There is limited evidence regarding the mechanisms of acute physiological and chronic adaptive responses to eccentric cycling.

Effects of descending or ascending stair exercise on body composition, insulin sensitivity, and inflammatory markers in young Chinese women with obesity: A randomized controlled trial

We examined the effects of descending (DSE) or ascending (ASE) stair exercise on body composition, insulin sensitivity, and inflammatory markers in young Chinese women with obesity. Thirty-six participants were randomly assigned into three groups DSE, ASE and a control group. The DSE and ASE groups performed three sessions of stair walking per week for 12 weeks with a gradual increase in repetitions. Following the exercise interventions, body composition related variables obtained by Dual-energy X-ray absorptiometry scans significantly decreased. Abdominal fat decreased in the DSE group only. Moreover, Insulin sensitivity improved significantly 3.5-fold in the DSE group compared with ASE group (insulin: -33.2% vs. -9.8%, homoeostasis model assessment for insulin resistance: -35.6% vs. -10.8%). Pro-inflammatory factors showed significant decreases in tumour necrosis factor-α (TNF-α) (-39.9% vs. -23.2%) for both intervention groups. The reduction in TNF-α concentrations in the DSE group was significantly different compared to the other two groups. Interleukin-6 significantly decreased in both exercise protocols. Our results show that 12-weeks induced stair walking improved body composition parameters in Chinese females with obesity. The results also demonstrate the superiority of the DSE protocol for improving insulin sensitivity. These findings may be attributable to the decreases observed in TNF- α levels.

Resistance Exercise, Electrical Muscle Stimulation, and Whole-Body Vibration in Older Adults: Systematic Review and Meta-Analysis of Randomized Controlled Trials

It has been shown that resistance exercise (RT) is one of the most effective approaches to counteract the physical and functional changes associated with aging. This systematic review with meta-analysis compared the effects of RT, whole-body vibration (WBV), and electrical muscle stimulation (EMS) on muscle strength, body composition, and functional performance in older adults. A thorough literature review was conducted, and the analyses were limited to randomized controlled trials. In total, 63 studies were included in the meta-analysis (48 RT, 11 WBV, and 4 EMS). The results showed that RT and WBV are comparably effective for improving muscle strength, while the effects of EMS remains debated. RT interventions also improved some outcome measures related to functional performance, as well as the cross-sectional area of the quadriceps. Muscle mass was not significantly affected by RT. A limitation of the review is the smaller number of WBV and particularly EMS studies. For this reason, the effects of WBV and EMS could not be comprehensively compared to the effect of RT for all outcome measures. For the moment, RT or combinations of RT and WBV or EMS, is probably the most reliable way to improve muscle strength and functional performance, while the best approach to increase muscle mass in older adults remains open to further studies.

Effects of physical exercise in sarcopenia. A systematic review

From the third decade of life and due to multiple causes, muscle mass and strength are gradually lost, which affects the function of the musculoskeletal system. This combined loss of muscle mass and strength with aging is called sarcopenia, and is associated with greater morbidity and mortality in the elderly. Early treatment is therefore essential, and physical exercise is the therapeutic approach that has given the best results. This literature review intended to analyze the effect of physical exercise, excluding the role that other treatments proposed, including the nutritional approach, could play in the treatment of sarcopenia, refers to 12 articles. In studies including high intensity strength exercises in isolation, either alone or combined with aerobic exercise, improvements were seen in muscle mass, muscle strength, and functional test times. There is also a significant increase in fat-free mass in individuals who exercised more frequently (more than two sessions per week). Current evidence shows that strength-resistance training and its combination in multimodal programs with aerobic exercise show significantly beneficial effects on anthropometric and muscle function parameters. Programs of prescribed exercises including strength exercises adequate to the characteristics should therefore be adapted to the characteristics of each individual and replace the usual practice of prescribing aerobic exercises (walking) only.

The acute transcriptional response to resistance exercise: impact of age and contraction mode

Optimization of resistance exercise (RE) remains a hotbed of research for muscle building and maintenance. However, the interactions between the contractile components of RE (i.e. concentric (CON) and eccentric (ECC)) and age, are poorly defined. We used transcriptomics to compare age-related molecular responses to acute CON and ECC exercise. Eight young (21±1 y) and eight older (70±1 y) exercise-naïve male volunteers had vastus lateralis biopsies collected at baseline and 5 h post unilateral CON and contralateral ECC exercise. RNA was subjected to next-generation sequencing and differentially expressed (DE) genes tested for pathway enrichment using Gene Ontology (GO). The young transcriptional response to CON and ECC was highly similar and older adults displayed moderate contraction-specific profiles, with no GO enrichment. Age-specific responses to ECC revealed 104 DE genes unique to young, and 170 DE genes in older muscle, with no GO enrichment. Following CON, 15 DE genes were young muscle-specific, whereas older muscle uniquely expressed 147 up-regulated genes enriched for cell adhesion and blood vessel development, and 28 down-regulated genes involved in mitochondrial respiration, amino acid and lipid metabolism. Thus, older age is associated with contraction-specific regulation often without clear functional relevance, perhaps reflecting a degree of stochastic age-related dysregulation.

Sarcopenia: A Contemporary Health Problem among Older Adult Populations

Sarcopenia, a geriatric disease characterized by a progressive loss of skeletal muscle mass and loss of muscle function, constitutes a rising, often undiagnosed health problem. Its prevalence in the elderly population is largely considered variable, as it ranges from 5% to 50% depending on gender, age, pathological conditions as well as diagnostic criteria. There is no one unified approach of treatment or assessment, which makes sarcopenia even harder to assess. There is a pressing need to provide better diagnosis, diagnostics, prevention, and individualized health care. Physical activity and nutrition are the main studied ways to prevent sarcopenia, and they also offer better outcomes. This review aims to report the prevalence of sarcopenia in older adults, its etiology, prevention, and treatment techniques.

Eccentric Cycling Training Improves Health-Related Quality of Life in Adolescents with Obesity

INTRODUCTION

While eccentric (ECC) training appears to be more efficient than concentric (CON) training at improving body composition in adolescent with obesity, its impact on health-related quality of life (HRQOL) has never been studied.

OBJECTIVE

The aim of this study is to compare the effects of 2 cycling training modalities, i.e., ECC vs. CON, in adolescents with obesity on HRQOL and health perception (HP).

METHODS

A total of 24 adolescents with obesity, aged 12-16 years, were randomized to either a 12-week ECC or a CON cycling training program performed at the same oxygen consumption (VO2). Anthropometric measurements, body composition, maximal incremental tests, HRQOL (Vécu et Santé Percue de l'Adolescent [VSP-A], Medical Outcome Study Short Form [SF-36]), and HP were assessed at before and after training.

RESULTS AND CONCLUSION

Both CON and ECC cycling trainings promoted significant improvements in BMI, VO2peak, total fat mass, and fat-free mass, with better improvements in body composition parameters in the ECC group (p < 0.05). The VSP-A total score increased after CON (p < 0.01) and ECC (p < 0.001) training, with better enhancement for the ECC group (p < 0.05). The SF-36 physical score increased after both CON (p < 0.01) and ECC (p < 0.001) trainings. The global HP score increased only after ECC training (p < 0.001). Except for the energy-vitality item, no significant correlation was found between changes in HRQOL and its subdomains and anthropometric, body composition, and functional parameters. Both ECC and CON cycling trainings are associated with positive changes in HRQOL and HP. However, ECC seems to induce greater improvements in HRQL and HP than CON cycling training, which is probably not due to the anthropometric, body composition, and functional changes.

Eccentric Muscle Contractions: Risks and Benefits

Eccentric contractions, characterized by the lengthening of the muscle-tendon complex, present several unique features compared with other types of contractions, which may lead to unique adaptations. Due to its specific physiological and mechanical properties, there is an increasing interest in employing eccentric muscle work for rehabilitation and clinical purposes. However, unaccustomed eccentric exercise is known to cause muscle damage and delayed pain, commonly defined as “Delayed-Onset Muscular Soreness” (DOMS). To date, the most useful preventive strategy to avoid these adverse effects consists of repeating sessions involving submaximal eccentric contractions whose intensity is progressively increased over the training. Despite an increased number of investigations focusing on the eccentric contraction, a significant gap still remains in our understanding of the cellular and molecular mechanisms underlying the initial damage response and subsequent adaptations to eccentric exercise. Yet, unraveling the molecular basis of exercise-related muscle damage and soreness might help uncover the mechanistic basis of pathological conditions as myalgia or neuromuscular diseases. In addition, a better insight into the mechanisms governing eccentric training adaptations should provide invaluable information for designing therapeutic interventions and identifying potential therapeutic targets.

Cognitive demand of eccentric versus concentric cycling and its effects on post-exercise attention and vigilance

PURPOSE

This study tested the hypotheses that eccentric cycling (ECC) would be more cognitively demanding than concentric cycling (CONC), and attention and vigilance would improve more after ECC than CONC.

METHODS

Thirty young adults performed CONC and two bouts of ECC (ECC1 and ECC2) for 20 min at a similar workload (227.5 ± 51.5 W) with 1-week apart. Cognitive load during exercise was assessed by the average error from the target torque over 1200 (60 rpm × 20 min) revolutions, choice reaction time (CRT), the NASA-task load index (NASA-TLX), and prefrontal cortex oxygenation and deoxygenation (HHb) by near-infrared spectroscopy. Attention and vigilance were assessed by a sustained attention to response task (SART) before, immediately, and at every 15 min for 60 min after exercise or sitting (control).

RESULTS

Heart rate was lower during ECC1 (115.5 ± 20.3 bpm) and ECC2 (116.7 ± 21.0 bpm) than CONC (156.9 ± 19.4 bpm). The torque error was greater for ECC1 (26.1 ± 9.0%) and ECC2 (19.4 ± 9.0%) than CONC (10.8 ± 3.7%). CRT (CONC: 602.8 ± 69.0, ECC1: 711.1 ± 113.0, ECC2: 693.6 ± 122.6 ms) and mental demand in NASA-TLX (46.8 ± 25.8, 80.0 ± 15.3, 60.3 ± 17.6) were greater for ECC1 and ECC2 than CONC. Decreases in HHb were greater for ECC1 (- 0.41 ± 0.37 µM) and ECC2 (- 0.40 ± 0.40 µM) than CONC (0.10 ± 0.40 µM) and control (- 0.21 ± 0.28 µM). Attention and vigilance decreased 2-8% after 20-min sitting, but improved 2-10% immediately after ECC2, and did not decline from the baseline for 30 min after ECC1 or 60 min after CONC and ECC2.

CONCLUSION

Cognitive load was greater during ECC than CONC, but post-exercise attention and vigilance changes were not largely different between ECC and CONC.

Impact of Eccentric or Concentric Training on Body Composition and Energy Expenditure

PURPOSE

To compare the effects of 8-wk eccentric (ECC) versus concentric (CON) training using downhill and uphill running in rats on whole body composition, bone mineral density (BMD), and energy expenditure.

METHODS

Animals were randomly assigned to one of the following groups: 1) control (CTRL), 2) +15% uphill-running slope (CON), 3) -15% downhill-running slope (ECC15), and 4) -30% downhill-running slope (ECC30). Those programs enabled to achieve conditions of isopower output for CON and ECC15 and of iso-oxygen uptake (V˙O2) for CON and ECC30. Trained rats ran 45 min at 15 m·min five times per week. Total body mass, fat body mass, and lean body mass (LBM) measured through EchoMRI™, and 24-h energy expenditure including basal metabolic rate (BMR) assessed using PhenoMaster/LabMaster™ cage system were obtained before and after training. At sacrifice, the right femur was collected for bone parameters analysis.

RESULTS

Although total body mass increased in all groups over the 8-wk period, almost no change occurred for fat body mass in exercised groups (CON, -4.8 ± 6.18 g; ECC15, 0.6 ± 3.32 g; ECC30, 2.6 ± 6.01 g). The gain in LBM was mainly seen for ECC15 (88.9 ± 6.85 g) and ECC30 (101.6 ± 11.07 g). ECC was also seen to positively affect BMD. An increase in BMR from baseline was seen in exercise groups (CON, 13.9 ± 4.13 kJ·d; ECC15, 11.6 ± 5.10 kJ·d; ECC30, 18.3 ± 4.33 kJ·d) but not in CTRL one. This difference disappeared when BMR was normalized for LBM.

CONCLUSIONS

Results indicate that for iso-V˙O2 training, the impact on LBM and BMD is enhanced with ECC as compared with CON, and that for isopower but lower V˙O2 ECC, an important stimulus for adaptation is still observed. This provides further insights for the use of ECC in populations with cardiorespiratory exercise limitations.

Neuromuscular and Perceptual Responses to Sub-Maximal Eccentric Cycling

Objective

Eccentric (ECC) cycle-ergometers have recently become commercially-available, offering a novel method for rehabilitation training. Many studies have reported that ECC cycling enables the development of higher levels of muscular force at lower cardiorespiratory and metabolic loads, leading to greater force enhancements after a training period. However, fewer studies have focused on the specific perceptual and neuromuscular changes. As the two latter aspects are of major interest in clinical settings, this review aimed to present an overview of the current literature centered on the neuromuscular and perceptual responses to submaximal ECC cycling in comparison to concentric (CON) cycling.

Design

Narrative review of the literature.

Results

At a given mechanical workload, muscle activation is lower in ECC than in CON while the characteristics of the musculo-articular system (i.e., muscle-tendon unit, fascicle, and tendinous tissue length) are quite similar. At a given heart rate or oxygen consumption, ECC cycling training results in greater muscular hypertrophy and strength gains than CON cycling. On the contrary, CON cycling training seems to enhance more markers of muscle aerobic metabolism than ECC cycling performed at the same heart rate intensity. Data concerning perceptual responses, and neuromuscular mechanisms leading to a lower muscle activation (i.e., neural commands from cortex to muscular system) at a given mechanical workload are scarce.

Conclusion

Even though ECC cycling appears to be a very useful tool for rehabilitation purposes the perceptual and neural commands from cortex to muscular system during exercise need to be further studied.

Eccentric cycling is more efficient in reducing fat mass than concentric cycling in adolescents with obesity

The benefits of eccentric (ECC) training on fat mass (FM) remain underexplored. We hypothesized that in obese adolescents, ECC cycling training is more efficient for decreasing whole-body FM percentage compared to concentric (CON) performed at the same oxygen consumption (VO₂ ). Twenty-four adolescents aged 13.4 ± 1.3 years (BMI > 90th percentile) were randomized to ECC or CON. They performed three cyclo-ergometer sessions per week (30 min per session) for 12 weeks: two habituation, 5 at 50% VO_2peak , and 5 at 70% VO_2peak . Anthropometric measurements, body composition, maximal incremental CON tests, strength tests, and blood samples were assessed pre- and post-training. Whole-body FM percentage decreased significantly after compared to pretraining in both groups, though to a larger extent in the ECC group (ECC: -10% vs CON: -4.2%, P < 0.05). Whole-body lean mass (LM) percentage increased significantly in both groups after compared to pretraining, with a greater increase in the ECC group (ECC: 3.8% vs CON: 1.5%, P <0.05). The improvements in leg FM and LM percentages were greater in the ECC group (-6.5% and 3.0%, P = 0.01 and P < 0.01). Quadriceps isometric and isokinetic ECC strength increased significantly more in the ECC group (28.3% and 21.3%, P < 0.05). Both groups showed similar significant VO_2peak improvement (ECC: 15.4% vs CON: 10.3%). The decrease in homeostasis model assessment of insulin resistance index was significant in the ECC group (-19.9%). In conclusion, although both ECC and CON cycling trainings are efficient to decrease FM, ECC induces greater FM reduction, strength gains, and insulin resistance improvements and represents an optimal modality to recommend for obese adolescents.

Strength and Step Activity After Eccentric Resistance Training in Those With Incomplete Spinal Cord Injuries

Background: Individuals with spinal cord injuries (SCIs) often experience general weakness in the lower extremities that undermines daily step activity. Objective: To investigate the efficacy of eccentrically biased resistance training on lower extremity strength and physical activity of individuals with spinal injuries. Methods: Individuals with long-standing incomplete SCIs (N = 11) capable of completing a 10-meter walk assessment were included. All participants who completed the familiarization period finished the training. Individuals trained two times per week for 12 weeks on a lower body eccentric resistance training machine. It was hypothesized that the outcome variables (eccentric strength, isometric strength, and daily step physical activity) would improve as a result of the training intervention. Results: Eccentric strength [F(1.27, 12.71) = 8.42, MSE = 1738.35, H-F p = .009] and isometric strength [F(1.97, 19.77) = 7.10, MSE = 11.29, H-F p = .005] improved as a result of the training while daily step activity remained unchanged [F(2.00, 18.00) = 2.73, MSE = 216,836.78, H-F p = .092]. Conclusions: Eccentric resistance training improves eccentric and isometric strength. These physiological adaptations may translate to improved gait mechanics, but further study is required to identify this potential crossover effect.

Eccentric Training Improves Body Composition by Inducing Mechanical and Metabolic Adaptations: A Promising Approach for Overweight and Obese Individuals

Skeletal muscle generates force by either shortening (concentrically) or lengthening (eccentrically). Eccentric (ECC) exercise is characterized by a lower metabolic demand and requires less muscle activity than concentric (CON) exercise at the same level of exerted force. However, the specific effect of ECC training vs. CON training on lean and fat mass remains underexplored. The first aim of this paper was to review the available evidence regarding the effects of ECC training on whole body and segmental lean and fat mass and, when possible, compare these with the effects of CON training. The second aim was to provide some insights into the main mechanical, physiological, and metabolic adaptations of ECC training that contribute to its effects on body composition. The third aim was to determine the beneficial effects of ECC exercise on health-related parameters in overweight and obese patients. ECC training is an effective modality to improve lean mass, but when matched for load or work, the difference between ECC and CON trainings seems unclear. A few studies reported that ECC training is also efficient at reducing fat mass. By increasing post-exercise resting energy expenditure, modifying metabolic substrate, and improving both blood lipid profile and insulin resistance, ECC training is a potential exercise modality for individuals with chronic conditions such as those who are overweight and obese. Further investigations using standardized experimental conditions, examining not only segmental but also whole body composition, are required to compare ECC and CON trainings.

Eccentric cycling emphasising a low cardiopulmonary demand increases leg strength equivalent to workload matched concentric cycling in middle age sedentary males

OBJECTIVES

This study determined if eccentric endurance cycling, eliciting a low cardiovascular demand, could stimulate muscle strength adaptations in sedentary middle-aged males.

DESIGN

Twenty-four middle-aged sedentary males were allocated to concentric (CON) or matched workload eccentric (ECC) cycling (60% peak concentric workload) according to their maximal voluntary isometric quadriceps strength.

METHODS

Seventeen participants [42.7±8.3 years, BMI 28.6±5.2, peak oxygen consumption [30.5±5.8mLkg^-1min^-1] completed 8 weeks (2 sessions per week) of CON (n=8) or ECC (n=9) cycle training. Incline leg press (6RM), maximal voluntary isometric contraction (MVIC) torque of the quadriceps and peak oxygen consumption were measured at baseline and 8 weeks.

RESULTS

Eccentric cycle training resulted in low cardiovascular demand (CON 154±2; ECC 95±3bmin^-1P<0.05) and ratings of perceived exertion (CON 14.9±0.3; ECC 9.5±0.3/20 P<0.05). Peak oxygen consumption improved within the CON group (Baseline 27.4±2.1; 8 weeks: 30.0±1.7mLkg^-1min^-1P<0.05) and not within the ECC group (Baseline 33.2±1.5; 8 weeks 33.3±1.6mLkg^-1min^-1) following training. 6RM (CON 176±20; ECC 192±11kg) and MVIC (CON 199±25; ECC 199±25Nm) strength were equivalent at baseline (P>0.05). Both groups significantly increased 6RM (CON 13.0±3.0; ECC 10.7±3.2%) and MVIC (CON 12.9±4.3; ECC 18.8±3.0%) relative to their own baseline (P<0.05). Therefore, improved leg strength was equivalent between CON and ECC groups despite the varied training (P>0.05).

CONCLUSIONS

In sedentary middle age males, eccentric endurance cycling with a low cardiovascular demand, increased both quadriceps isometric and 6RM strength comparable to a matched workload concentric cycling program.

Comparing the effects of two distinct eccentric modalities to traditional resistance training in resistance trained, higher functioning older adults

BACKGROUND

The effects of eccentric resistance exercise are of interest in the older adult cohort, but to our knowledge, there is no research on the relative effects of different eccentric modalities on a range of outcomes in higher functioning, resistance trained older adults.

METHODS

33 resistance-trained older adults (aged 67±4.5years) were randomized into one of three supervised training groups: traditional (TRE), eccentric only (ERE) or eccentrically biased resistance exercise (EBRE) on a 45°, plate-loaded leg press machine. Participants trained twice per week with maximal strength, functional capacity, body composition and blood biomarkers measured before and after the eight-week intervention.

RESULTS

Both eccentric and concentric strength, and important functional tasks for independent living significantly improved independent of group. Body composition and blood biomarkers were found to significantly improve in the EBRE group only however, no statistical differences were found between groups.

CONCLUSION

Compared to traditional resistance training, the two eccentric modalities investigated here were equally effective for improvements in maximum muscular strength, functional capacity, body composition and metabolic biomarkers. When training the resistance trained older adult, very heavy isoinertial external loads (at least 70% of one repetition maximum) are effective irrespective of contraction mode. With heavy strength training, resistance trained older adults can continue to expect improvements in health and function.

Eccentric versus traditional resistance exercise for older adult fallers in the community: a randomized trial within a multi-component fall reduction program

BACKGROUND

Addressing muscle deficits within a multi-component exercise fall reduction program is a priority, especially for the highest risk older adults, i.e., those who have fallen previously. Eccentric resistance exercise with its high-force producing potential, at a low energetic cost, may be ideally-suited to address muscle impairments in this population. The purpose of this study was to compare the effects of resistance exercise via negative, eccentrically-induced, work (RENEW) versus traditional (TRAD) resistance exercise on mobility, balance confidence, muscle power and cross sectional area, as well as the number of days high fall risk older adults survived without a fall event over a 1 year period.

METHODS

Randomized, two group, four time point (over 1 year) clinical trial testing RENEW versus TRAD as part of a 3 month multi-component exercise fall reduction program (MCEFRP). Primary outcomes of mobility, balance confidence, muscle power output and cross sectional area were analyzed using mixed effects modeling. The secondary outcomes of days to fall and days to near-fall were analyzed using survival analysis.

RESULTS

The MCEFRP did have an effect on fall risk factors considered reversible with exercise interventions though there was no differential effect of RENEW versus TRAD (p = 0.896) on mobility, balance confidence, muscle power and cross sectional area. There were also no group differences in the number of days survived without a fall (p = 0.565) or near-fall (p = 0.678). Despite 100% of participants having at least one fall in the year prior to the MCEFRP, however, after 3 months of exercise and 9 months of follow-up <50% had experienced a fall or near fall.

CONCLUSIONS

There were no differential effects of RENEW or TRAD as components of a MCEFRP on the primary or secondary outcomes. The two modes of resistance exercise had identical effects on fall risk and fall-free survival.

TRIAL REGISTRATION

NCT01080196 ; March 2, 2010 (retrospectively registered).

Chronic eccentric arm cycling improves maximum upper-body strength and power

INTRODUCTION

Eccentric leg cycling (cycle ergometry adapted to impose muscle lengthening contractions) offers an effective exercise for restoring lower-body muscular function, maintaining health, and improving performance in clinical and athletic populations.

PURPOSE

We extended this model to the upper body and evaluated the effectiveness of a 7-week eccentric arm cycling (ECC_arm) intervention to improve upper-body muscular function. We also explored whether ECC_arm would alter arterial function.

METHODS

Participants performed ECC_arm (n = 9) or concentric arm cycling (CON_arm; n = 8) 3×/week while training intensity increased (5-20 min, 60-70% upper-body peak heart rate). Maximum elbow extensor strength, upper-body concentric power, and peripheral and central arterial stiffness were assessed before and after training.

RESULTS

During training, heart rates and perceived exertion did not differ between groups (~68% upper-body peak heart rate, ~12 Borg units, both P > 0.05), whereas power during ECC_arm was ~2× that for CON_arm (122 ± 43 vs. 59 ± 20 W, P < 0.01). Muscle soreness for ECC_arm was greater than CON_arm (P = 0.02), however, soreness was minimal for both groups (<0.50 cm). Following training, ECC_arm exhibited greater changes in elbow extensor strength (16 ± 10 vs. 1 ± 9%, P = 0.01) and upper-body power (6 ± 8 vs. -3 ± 7%, P < 0.01) compared to CON_arm. Peripheral and central arterial stiffness did not change for either group (both P > 0.05).

CONCLUSION

Upper-body eccentric exercise improved dynamic muscular function while training at low exertion levels. Results occurred with minimal soreness and without compromising arterial function. ECC_arm findings parallel eccentric leg cycling findings and indicate that eccentric cycle ergometry offers a robust model for enhancing upper-body muscular function. ECC_arm could have applications in rehabilitation and sport training.

Superior Effects of Eccentric to Concentric Knee Extensor Resistance Training on Physical Fitness, Insulin Sensitivity and Lipid Profiles of Elderly Men

It has been reported that eccentric training of knee extensors is effective for improving blood insulin sensitivity and lipid profiles to a greater extent than concentric training in young women. However, it is not known whether this is also the case for elderly individuals. Thus, the present study tested the hypothesis that eccentric training of the knee extensors would improve physical function and health parameters (e.g., blood lipid profiles) of older adults better than concentric training. Healthy elderly men (60–76 years) were assigned to either eccentric training or concentric training group (n = 13/group), and performed 30–60 eccentric or concentric contractions of knee extensors once a week. The intensity was progressively increased over 12 weeks from 10 to 100% of maximal concentric strength for eccentric training and from 50 to 100% for concentric training. Outcome measures were taken before and 4 days after the training period. The results showed that no sings of muscle damage were observed after any sessions. Functional physical fitness (e.g., 30-s chair stand) and maximal concentric contraction strength of the knee extensors increased greater (P ≤ 0.05) after eccentric training than concentric training. Homeostasis model assessment, oral glucose tolerance test and whole blood glycosylated hemoglobin showed improvement of insulin sensitivity only after eccentric training (P ≤ 0.05). Greater (P ≤ 0.05) decreases in fasting triacylglycerols, total, and low-density lipoprotein cholesterols were evident after eccentric training than concentric training, and high-density lipoprotein cholesterols increased only after eccentric training. These results support the hypothesis and suggest that it is better to focus on eccentric contractions in exercise medicine.

Eccentric Ergometer Training Promotes Locomotor Muscle Strength but Not Mitochondrial Adaptation in Patients with Severe Chronic Obstructive Pulmonary Disease

Eccentric ergometer training (EET) is increasingly being proposed as a therapeutic strategy to improve skeletal muscle strength in various cardiorespiratory diseases, due to the principle that lengthening muscle actions lead to high force-generating capacity at low cardiopulmonary load. One clinical population that may particularly benefit from this strategy is chronic obstructive pulmonary disease (COPD), as ventilatory constraints and locomotor muscle dysfunction often limit efficacy of conventional exercise rehabilitation in patients with severe disease. While the feasibility of EET for COPD has been established, the nature and extent of adaptation within COPD muscle is unknown. The aim of this study was therefore to characterize the locomotor muscle adaptations to EET in patients with severe COPD, and compare them with adaptations gained through conventional concentric ergometer training (CET). Male patients were randomized to either EET (n = 8) or CET (n = 7) for 10 weeks and matched for heart rate intensity. EET patients trained on average at a workload that was three times that of CET, at a lower perception of leg fatigue and dyspnea. EET led to increases in isometric peak strength and relative thigh mass (p < 0.01) whereas CET had no such effect. However, EET did not result in fiber hypertrophy, as morphometric analysis of muscle biopsies showed no increase in mean fiber cross-sectional area (p = 0.82), with variability in the direction and magnitude of fiber-type responses (20% increase in Type 1, p = 0.18; 4% decrease in Type 2a, p = 0.37) compared to CET (26% increase in Type 1, p = 0.04; 15% increase in Type 2a, p = 0.09). EET had no impact on mitochondrial adaptation, as revealed by lack of change in markers of mitochondrial biogenesis, content and respiration, which contrasted to improvements (p < 0.05) within CET muscle. While future study is needed to more definitively determine the effects of EET on fiber hypertrophy and associated underlying molecular signaling pathways in COPD locomotor muscle, our findings promote the implementation of this strategy to improve muscle strength. Furthermore, contrasting mitochondrial adaptations suggest evaluation of a sequential paradigm of eccentric followed by concentric cycling as a means of augmenting the training response and attenuating skeletal muscle dysfunction in patients with advanced COPD.

Moderate Load Eccentric Exercise; A Distinct Novel Training Modality

Over the last 20 years a number of studies have been published using progressive eccentric exercise protocols on motorized ergometers or similar devices that allow for controlled application of eccentric loads. Exercise protocols ramp eccentric loads over an initial 3 weeks period in order to prevent muscle damage and delayed onset muscle soreness. Final training loads reach 400-500 W in rehabilitative settings and over 1200 W in elite athletes. Training is typically carried out three times per week for durations of 20-30 min. This type of training has been characterizes as moderate load eccentric exercise. It has also been denoted RENEW (Resistance Exercise via Negative Eccentric Work by LaStayo et al., 2014). It is distinct from plyometric exercises (i.e., drop jumps) that impose muscle loads of several thousand Watts on muscles and tendons. It is also distinct from eccentric overload training whereby loads in a conventional strength training setting are increased in the eccentric phase of the movement to match concentric loads. Moderate load eccentric exercise (or RENEW) has been shown to be similarly effective as conventional strength training in increasing muscle strength and muscle volume. However, as carried out at higher angular velocities of joint movement, it reduces joint loads. A hallmark of moderate load eccentric exercise is the fact that the energy requirements are typically 4-fold smaller than in concentric exercise of the same load. This makes moderate load eccentric exercise training the tool of choice in medical conditions with limitations in muscle energy supply. The use and effectiveness of moderate load eccentric exercise has been demonstrated mostly in small scale studies for cardiorespiratory conditions, sarcopenia of old age, cancer, diabetes type 2, and neurological conditions. It has also been used effectively in the prevention and rehabilitation of injuries of the locomotor system in particular the rehabilitation after anterior cruciate ligament surgery.

Pericapillary basement membrane thickening in human skeletal muscles

The basement membrane (BM) surrounding capillaries in skeletal muscles varies physiologically in thickness according to age, physical fitness, and anatomical site in humans. Furthermore, the pericapillary BM thickness (CBMT) increases pathophysiologically during several common disease states, including peripheral arterial disease and diabetes mellitus. This review on CBM thickening in human skeletal muscles is two pronged. First, it addresses the advantages/disadvantages of grid- and tablet-based measuring and morphometric techniques that are implemented to assess the CBMT on transmission electron micrographs. Second, it deals with the biology of CBM thickening in skeletal muscles, particularly its possible causes, molecular mechanisms, and functional impact. CBM thickening is triggered by several physical factors, including diabetes-associated glycation, hydrostatic pressure, and inflammation. Increased biosynthesis of type IV collagen expression or repetitive cycles in pericyte or endothelial cell degeneration/proliferation appear to be most critical for CBM accumulation. A thickened CBM obviously poses a greater barrier for diffusion, lowers the microvascular elasticity, and impedes transcytosis of inflammatory cells. Our own morphometric data reveal the CBM enlargement to be not accompanied by the pericyte coverage. Owing to an overlap or redundancy in the capillary supply, CBM thickening in skeletal muscles might not be such a devastating occurrence as in organs with endarterial circulation (e.g., kidney and retina). CBM growth in skeletal muscles can be reversed by training or administration of antidiabetic drugs. In conclusion, CBM thickening in skeletal muscles is a microvascular remodeling process by which metabolic, hemodynamic, and inflammatory forces are integrated together and which could play a hitherto underestimated role in etiology/progression of human diseases.

Chronic Eccentric Exercise and the Older Adult

Eccentric exercise has gained increasing attention as a suitable and promising intervention to delay or mitigate the known physical and physiological declines associated with aging. Determining the relative efficacy of eccentric exercise when compared with the more conventionally prescribed traditional resistance exercise will support evidence-based prescribing for the aging population. Thus, original research studies incorporating chronic eccentric exercise interventions in the older adult population were included in this review. The effects of a range of eccentric exercise modalities on muscular strength, functional capacity, body composition, muscle architecture, markers of muscle damage, the immune system, cardiovascular system, endocrine system, and rating of perceived exertion were all reviewed as outcomes of particular interest in the older adult. Muscular strength was found to increase most consistently compared with results from traditional resistance exercise. Functional capacity and body composition showed significant improvements with eccentric endurance protocols, especially in older, frail or sedentary cohorts. Muscle damage was avoided with the gradual progression of novel eccentric exercise, while muscle damage from intense acute bouts was significantly attenuated with repeated sessions. Eccentric exercise causes little cardiovascular stress; thus, it may not generate the overload required to elicit cardiovascular adaptations. An anabolic state may be achievable following eccentric exercise, while improvements to insulin sensitivity have not been found. Finally, rating of perceived exertion during eccentric exercise was often significantly lower than during traditional resistance exercise. Overall, evidence supports the prescription of eccentric exercise for the majority of outcomes of interest in the diverse cohorts of the older adult population.

Effects of eccentric-focused and conventional resistance training on strength and functional capacity of older adults

The aim of the study was to assess the effect of eccentric training using a constant load with longer exposure time at the eccentric phase on knee extensor muscle strength and functional capacity of elderly subjects in comparison with a conventional resistance training program. Twenty-six healthy elderly women (age = 67 ± 6 years) were randomly assigned to an eccentric-focused training group (ETG; n = 13) or a conventional training group (CTG; n = 13). Subjects underwent 12 weeks of resistance training twice a week. For the ETG, concentric and eccentric phases were performed using 1.5 and 4.5 s, respectively, while for CTG, each phase lasted 1.5 s. Maximum dynamic strength was assessed by the one-repetition maximum (1RM) test in the leg press and knee extension exercises, and for functional capacity, subjects performed specific tests (6-m walk test, timed up-and-go test, stair-climbing test, and chair-rising test). Both groups improved knee extension 1RM (24-26 %; p = 0.021), timed up-and-go test (11-16 %; p < 0.001), 6-m walk test (9-12 %; p = 0.004), stair-climbing test (8-13 %; p = 0.007), and chair-rising test (15-16 %; p < 0.001), but there was no significant difference between groups. In conclusion, the strategy of increasing the exposure time at the eccentric phase of movement using the same training volume and intensity does not promote different adaptations in strength or functional capacity compared to conventional resistance training in elderly woman.

[Frailty from the rehabilitation medicine point of view]

BACKGROUND

Frailty syndrome exerts an increasing challenge to health care systems. Thus, rehabilitative interventions should be taken to prevent or slow this syndrome.

METHODS

Based on the definitions of frailty and rehabilitation, the present work gives an overview of current treatment options. The methodology and evidence for device-assisted training forms such as neuromuscular electrical stimulation or mechanical muscle stimulation are discussed. The use of various forms of training for frail patients is critically discussed.

RESULTS

Among other things, age- and disease-related changes in skeletal muscle play a central role in the development of frailty. Progressive strength training is an evidence-based rehabilitative strategy to improve function. Since this form of strength training can be a vigorous exercise especially for the elderly and infirmed, it can be offered as an alternative form of training.

Physiological comparison of concentric and eccentric arm cycling in males and females

Lower body eccentric exercise is well known to elicit high levels of muscular force with relatively low cardiovascular and metabolic strain. As a result, eccentric exercise has been successfully utilised as an adaptive stressor to improve lower body muscle function in populations ranging from the frail and debilitated, to highly-trained individuals. Here we investigate the metabolic, cardiorespiratory, and energy costs of upper body eccentric exercise in a healthy population. Seven men and seven women performed 4-min efforts of eccentric (ECC) or concentric (CON) arm cycling on a novel arm ergometer at workloads corresponding to 40, 60, and 80% of their peak workload as assessed in an incremental concentric trial. The heart rate, ventilation, cardiac output, respiratory exchange ratio, and blood lactate concentrations were all clearly greater in CON condition at all of the relative workloads (all p<0.003). Effect size calculations demonstrated that the magnitude of the differences in VO2 and work economy between the ECC and CON exercise ranged from very large to extremely large; however, in no case did mechanical efficiency (η(MECH)) differ between the conditions (all p>0.05). In contrast, delta efficiency (ηΔ), as previously defined by Coyle and colleagues in 1992, demonstrated a sex difference (men>women; p<0.05). Sex differences were also apparent in arteriovenous oxygen difference and heart rate during CON. Here, we reinforce the high-force, low cost attributes of eccentric exercise which can be generalised to the muscles of the upper body. Upper body eccentric exercise is likely to form a useful adjunct in debilitative, rehabilitative, and adaptive clinical exercise programs; however, reports of a shift towards an oxidative phenotype should be taken into consideration by power athletes. We suggest delta efficiency as a sensitive measure of efficiency that allowed the identification of sex differences.

Mechanical, hormonal, and hypertrophic adaptations to 10 weeks of eccentric and stretch-shortening cycle exercise training in old males

The growth promoting effects of eccentric (ECC) contractions are well documented but it is unknown if the rate of stretch per se plays a role in such muscular responses in healthy aging human skeletal muscle. We tested the hypothesis that exercise training of the quadriceps muscle with low rate ECC and high rate ECC contractions in the form of stretch-shortening cycles (SSCs) but at equal total mechanical work would produce rate-specific adaptations in healthy old males age 60-70. Both training programs produced similar improvements in maximal voluntary isometric (6%) and ECC torque (23%) and stretch-shortening cycle function (reduced contraction duration [24%] and enhanced elastic energy storage [12%]) (p<0.05). The rate of torque development increased 30% only after SSC exercise (p<0.05). Resting testosterone and cortisol levels were unchanged but after each program the acute exercise-induced cortisol levels were 12-15% lower (p<0.05). Both programs increased quadriceps size 2.5% (p<0.05). It is concluded that both ECC and SSC exercise training produces favorable adaptations in healthy old males' quadriceps muscle. Although the rate of muscle tension during the SSC vs. ECC contractions was about 4-fold greater, the total mechanical work seems to regulate the hypetrophic, hormonal, and most of the mechanical adaptations. However, SSC exercise was uniquely effective in improving a key deficiency of aging muscle, i.e., its ability to produce force rapidly.

Molecular mechanisms of muscle plasticity with exercise

The skeletal muscle phenotype is subject to considerable malleability depending on use. Low-intensity endurance type exercise leads to qualitative changes of muscle tissue characterized mainly by an increase in structures supporting oxygen delivery and consumption. High-load strength-type exercise leads to growth of muscle fibers dominated by an increase in contractile proteins. In low-intensity exercise, stress-induced signaling leads to transcriptional upregulation of a multitude of genes with Ca(2+) signaling and the energy status of the muscle cells sensed through AMPK being major input determinants. Several parallel signaling pathways converge on the transcriptional co-activator PGC-1α, perceived as being the coordinator of much of the transcriptional and posttranscriptional processes. High-load training is dominated by a translational upregulation controlled by mTOR mainly influenced by an insulin/growth factor-dependent signaling cascade as well as mechanical and nutritional cues. Exercise-induced muscle growth is further supported by DNA recruitment through activation and incorporation of satellite cells. Crucial nodes of strength and endurance exercise signaling networks are shared making these training modes interdependent. Robustness of exercise-related signaling is the consequence of signaling being multiple parallel with feed-back and feed-forward control over single and multiple signaling levels. We currently have a good descriptive understanding of the molecular mechanisms controlling muscle phenotypic plasticity. We lack understanding of the precise interactions among partners of signaling networks and accordingly models to predict signaling outcome of entire networks. A major current challenge is to verify and apply available knowledge gained in model systems to predict human phenotypic plasticity.