Purpose This study aimed to determine the effects of bilateral and unilateral eccentric exercises on muscle damage and muscular physiological indices in healthy men. Methods Using a randomized ...crossover design, nine adult males without musculoskeletal disorders were divided into a bilateral eccentric exercise group (BEG, n=9) and a unilateral eccentric exercise group (UEG, n=9). Bilateral and unilateral eccentric exercises involved five sets of six repetitions of the rhythm metronome speed eccentric contraction 3 seconds at 110% one repetition maximum (1RM) using bilateral of BEG and the dominant and non-dominant of UEG separated by four weeks, respectively. Muscle damage (flexed and extended ROM, CIR, and VAS) and muscular physiological indices (muscle activity, muscle fatigue, and muscle tone) were measured before, immediately after (0 hour), 24, 48, 72, and 96 hours following bilateral and unilateral eccentric exercises. Results The flexed ROM, CIR, VAS, muscle activity, and muscle tone were significantly increased after both bilateral and unilateral eccentric exercises (p<.05, respectively). Extended ROM and muscle activity significantly decreased after both bilateral and unilateral eccentric exercises (p<.05, respectively). However, there was no significant interaction between side (S) and time and side (T×S). Conclusions These results showed that there was no difference in muscle damage and physiological indices after measuring and setting the 1RM muscle strength separated by bilateral and unilateral eccentric exercises.
The α
7
β
1
integrin is concentrated at the costameres of skeletal muscle and provides a critical link between the actin cytoskeleton and laminin in the basement membrane. We previously demonstrated ...that expression of the α
7
BX2 integrin subunit (MCK:α
7
BX2) preserves muscle integrity and enhances myofiber cross-sectional area following eccentric exercise. The purpose of this study was to utilize gene expression profiling to reveal potential mechanisms by which the α
7
BX2-integrin contributes to improvements in muscle growth after exercise. A microarray analysis was performed using RNA extracted from skeletal muscle of wild-type or transgenic mice under sedentary conditions and 3 h following an acute bout of downhill running. Genes with false discovery rate probability values below the cutoff of
P
< 0.05 (
n
= 73) were found to be regulated by either exercise or transgene expression. KEGG pathway analysis detected upregulation of genes involved in endoplasmic reticulum protein processing with integrin overexpression. Targeted analyses verified increased transcription of
Rpl13a
,
Nosip
,
Ang
,
Scl7a5
,
Gys1
,
Ndrg2
,
Hspa5
, and
Hsp40
as a result of integrin overexpression alone or in combination with exercise (
P
< 0.05). A significant increase in HSPA5 protein and a decrease in CAAT-enhancer-binding protein homologous protein (CHOP) were detected in transgenic muscle (
P
< 0.05). In vitro knockdown experiments verified integrin-mediated regulation of
Scl7a5
. The results from this study suggest that the α
7
β
1
integrin initiates transcription of genes that allow for protection from stress, including activation of a beneficial unfolded protein response and modulation of protein synthesis, both which may contribute to positive adaptations in skeletal muscle as a result of engagement in eccentric exercise.
Skeletal muscle adapts to exercise-induced damage by orchestrating several but still poorly understood mechanisms that endow protection from subsequent damage. Known widely as the repeated bout ...effect, we propose that neural adaptations, alterations to muscle mechanical properties, structural remodeling of the extracellular matrix, and biochemical signaling work in concert to coordinate the protective adaptation.
The pro- and anti-inflammatory macrophages are associated with insulin sensitivity and skeletal muscle regeneration. Infiltrating macrophages in skeletal muscle during a period of physical inactivity ...and subsequent reloading/rehabilitation in older adults is unknown, but may provide insight into mechanisms related to the development of metabolic disease and changes in muscle cell size. The purpose of this study was to determine if skeletal muscle macrophage infiltration is modulated differently between young and older adults after bed rest and exercise rehabilitation and if these responses are related to muscle and insulin sensitivity changes. 14 young and 9 older adults underwent 5-days of bed rest followed by 8-weeks of lower limb eccentric exercise rehabilitation (REHAB). Dual-energy X-ray absorptiometry, magnetic resonance imaging and myofiber analysis were used to identify muscle morphology and CLIX-IR and CLIX-β were used to assess insulin sensitivity. Skeletal muscle macrophages, CD68 (pan), CD11b (M1), CD163 (M2), CD206 (M2), were characterized using immunohistochemistry and gene expression. Insulin sensitivity, independent of age, decreased ~38% following bed rest and was restored following REHAB. We found robust age-related differences in muscle atrophy during bed rest, yet older and younger adults equally hypertrophied during REHAB. Interestingly, there were age-related differences in macrophage content (CD68+CD11b+ and CD68+CD11b− cells) but both young and old similarly increased macrophages with REHAB. Satellite cell changes during rehab corresponded to macrophage content changes. Muscle tissue resident macrophages and gene expression, were not associated with changes in insulin sensitivity following bed rest and REHAB. These data suggest that muscle macrophages are modulated as a result of exercise rehabilitation following bed rest and may more associated with muscle regrowth/hypertrophy rather than insulin sensitivity in young or older adults.
This trial was registered at clinicaltrials.gov as NCT01669590.
•Older adults (vs young) experienced atrophy during bed rest, but both groups gained lean mass similarly after rehabilitation.•Insulin sensitivity decreased after bed rest and returned to baseline levels after rehabilitation, independent of age.•There were age-related differences in skeletal muscle macrophages, but both groups increased macrophages after rehabilitation.•Changes in muscle macrophages corresponded to changes in satellite cells, but not insulin sensitivity during rehabilitation.
Background:
Patellar tendinopathy is a condition characterized by anterior knee activity–related pain. It has a high incidence among athletes engaged in jumping sports and may become a chronic ...condition. Nonoperative management is the first choice in these patients, and several nonsurgical treatment options have been proposed. Nonetheless, clear indications on the most effective approach to address patellar tendinopathy are still lacking.
Purpose:
To analyze the evidence on nonoperative options to treat chronic patellar tendinopathy through a systematic review of the literature and to perform a meta-analysis to identify the most effective nonsurgical option.
Study Design:
Systematic review and meta-analysis.
Methods:
The search was conducted with the PubMed and Cochrane databases on January 4, 2017. All clinical English-language reports of any level of evidence on nonsurgical treatment of patellar tendinopathy were included. The quality of each article was assessed by use of the Coleman score. A meta-analysis was performed on all articles reporting the Victorian Institute of Sport Assessment scale for patellar tendinopathy to evaluate the results of the most described treatments.
Results:
A total of 70 studies involving 2530 patients were included in the qualitative data synthesis. The Coleman score showed an overall poor study quality. The most described treatment groups that could be included in the meta-analysis were reported in 22 studies on eccentric exercise, extracorporeal shockwave therapy (ESWT), and platelet-rich plasma (PRP). Single and multiple PRP injections were evaluated separately. Eccentric exercise therapies obtained the best results (P < .05) at short-term (<6 months, mean 2.7 ± 0.7 months). However, multiple injections of PRP obtained the best results (P < .05), followed by ESWT and eccentric exercise, at long-term follow-up (≥6 months, mean 15.1 ± 11.3 months).
Conclusion:
The literature documents several nonsurgical approaches for the treatment of chronic patellar tendinopathy with important limitations in terms of study quality. The available evidence showed an overall positive outcome, but some differences have been highlighted. Eccentric exercises may seem the strategy of choice in the short-term, but multiple PRP injections may offer more satisfactory results at long-term follow-up and can be therefore considered a suitable option for the treatment of patellar tendinopathy.
ABSTRACTRomero-Parra, N, Cupeiro, R, Alfaro-Magallanes, VM, Rael, B, Rubio-Arias, JA, Peinado, AB, and Benito, PJ, IronFEMME Study Group. Exercise-induced muscle damage during the menstrual cycleA ...systematic review and meta-analysis. J Strength Cond Res XX(X)000–000, 2020—A strenuous bout of exercise could trigger damage of muscle tissue, and it is not clear how sex hormone fluctuations occurring during the menstrual cycle (MC) affect this response. The aims of this study were to systematically search and assess studies that have evaluated exercise-induced muscle damage (EIMD) in eumenorrheic women over the MC and to perform a meta-analysis to quantify which MC phases display the muscle damage response. The guidelines of the Preferred Reported Items for Systematic Reviews and Meta-Analysis were followed. A total of 19 articles were analyzed in the quantitative synthesis. Included studies examined EIMD in at least one phase of the following MC phasesearly follicular phase (EFP), late follicular phase (LFP), or midluteal phase (MLP). The meta-analysis demonstrated differences between MC phases for delayed onset muscle soreness (DOMS) and strength loss (p < 0.05), whereas no differences were observed between MC phases for creatine kinase. The maximum mean differences between pre-excercise and post-exercise for DOMS were EFP6.57 (4.42, 8.71), LFP5.37 (2.10, 8.63), and MLP3.08 (2.22, 3.95), whereas for strength loss were EFP−3.46 (−4.95, −1.98), LFP−1.63 (−2.36, −0.89), and MLP−0.72 (−1.07, −0.36) (p < 0.001). In conclusion, this meta-analysis suggests that hormone fluctuations throughout the MC affect EIMD in terms of DOMS and strength loss. Lower training loads or longer recovery periods could be considered in the EFP, when sex hormone concentrations are lower and women may be more vulnerable to muscle damage, whereas strength conditioning loads could be enhanced in the MLP.
Nordic Hamstring Exercise (NHE) is one of the best exercises proposed for injury prevention of hamstring muscles. However, its effects on lower extremity proprioception are unclear. The aim of this ...study was to investigate the immediate effects of a single bout of NHE on hip and knee joints’ proprioception.
Forty collegiate male soccer players participated in this study with a mean age of 22.85 ± 1.82 years and were randomized into either control (n = 20) or experimental (n = 20) groups. Each subject participated in pre-test measurements in which hip and knee active joints position sense (JPS) were assessed in standing and lying tasks using the image-capturing method. The experimental group then performed three sets of NHE with 10 repetitions in each set, while the control group rested for 10 min. Paired and independent t-tests were used for calculating the differences within and between groups on SPSS software, respectively. The level of significance was P ≤ 0.05.
Hip JPS in the lying task and knee JPS in both of the standing and lying tasks were impaired significantly after performing a single bout of NHE (P ≤ 0.05). However, the effects of this exercise on hip JPS in the standing task were not significant (P ≥ 0.05).
NHE performing with three sets of 10 repetitions can significantly impair hip and knee JPS immediately after exercise and reduce the proprioception acuity of the lower limbs. It is recommended to perform this exercise at a time rather than before training or match sessions.
Purpose Little is known about injury prevention practices in professional football clubs. The purpose of this study was therefore to determine the current perceptions and practices of premier league ...football clubs internationally concerning risk factors, testing and preventative exercises for non-contact injuries. Methods A survey was administered to 93 premier league football clubs internationally. The survey included four sections: (1) persons involved in the injury prevention programme: position, quantity, role, qualification; (2) perceptions regarding non-contact injury risk factors; (3) tests used to identify non-contact injury risk and (4) non-contact injury prevention exercises used, their perceived effectiveness and implementation strategies. Results 44 surveys were successfully returned (47%). The position of physiotherapist was the most represented position in the injury prevention programme. The top five perceived risk factors in rank order were previous injury, fatigue, muscle imbalance, fitness and movement efficiency. The five most commonly used tests to identify injury risk (in rank order) were functional movement screen, questionnaire, isokinetic dynamometry, physical tests and flexibility. The top five exercises used by clubs were (also in rank order) eccentric exercise, balance/proprioception, hamstring eccentric, core stability and, sharing the fifth position, Nordic hamstring and gluteus activation. Conclusions The survey revealed the most common perceptions and practices of premier league football clubs internationally regarding risk factors, testing and preventative exercises. The findings can enable reduction of the gap between research and practice.
Background: The appropriate activity of the knee agonist-antagonist muscles is important to resist against abnormal abduction-adduction moments loads around knee joint and reduce the risk of knee ...injuries. Exercise training has been commonly used as an intervention to improve neuromuscular activity of the synergic and/or agonist-antagonist muscles. However, maximizing the effectiveness of exercise interventions for improving neuromuscular activity between muscle groups has been less investigated. The aim of this study was to investigate the improvement in neuromuscular activity of quadriceps and hamstrings muscles after resistance eccentric training versus concentric training. Methods: 26 male subjects randomly recruited for this controlled laboratory study. Subjects were randomly divided into two groups, eccentric training group (No = 13), and concentric training group (No = 13). Maximal knee extension force and bipolar surface electromyography (EMG) signals from quadriceps and hamstrings muscles were recorded before and after concentric and eccentric strength training. Root mean square (RMS) was computed from raw EMG signals.Results: Percent increase in maximal voluntary isometric contraction (MIVC) of quadriceps muscle after eccentric training was significantly higher than that after concentric training (P < 0.05). Moreover, eccentric training resulted in a greater increase in RMS of EMG for quadriceps and hamstrings muscles compared to concentric exercise training (P < 0.05).Conclusion: The higher increase in neuromuscular activities within the quadriceps and hamstring muscles observed after eccentric exercise may indicate that resistance training using eccentric contraction is more effective in improving neuromuscular activity of the agonist and antagonist muscles.
Previous research has reported that people with Joint Hypermobility Syndrome (JHS) and Ehlers-Danlos Syndrome (EDS) generally experience a high rate of muscular injury and pain. However, there is ...limited research comparing the recovery times and length of Delayed Onset Muscle Soreness (DOMS) in individuals with JHS to non-hypermobile individuals in response to exercise.
The purpose of this study was to investigate JHS and its effects on DOMS and its recovery time.
Quasi-experimental, observational comparison.
Two groups including a hypermobile group (score >4 on Beighton Scale) and a non-hypermobile group all took part in five-second long standing eccentric bicep curls based using their one- repetition maximum (1-RM) of their dominant arm to failure in order to induce DOMS. Visual analog pain scale (VAS), McGill pain scale, resting arm angle, girth, and the pressure pain threshold, all domains of DOMS, were measured over a five-day period. Results were analyzed using ANOVA with time as the repeated factor.
Both groups experienced DOMS following the eccentric exercise. However, VAS reporting was significantly greater in the hypermobile group compared to the non-hypermobile group and there was a significant difference over time. However, other variables did not reveal any other significant findings between groups.
Individuals with JHS may experience greater DOMS and require more time to recover between treatment sessions. Therapists need to be aware that patients with hypermobility may experience higher pain levels related to exercise, and they need to adjust treatment parameters appropriately.
2b.
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