RESUMO
The bed rest (BR) is a ground-based model to simulate microgravity mimicking skeletal-muscle alterations as in spaceflight. Molecular coupling between bone and muscle might be involved in physiological and pathological conditions. Thus, the new myokine irisin and bone-muscle turnover markers have been studied during and after 10 days of BR. Ten young male individuals were subjected to 10 days of horizontal BR. Serum concentrations of irisin, myostatin, sclerostin, and haptoglobin were assessed, and muscle tissue gene expression on vastus lateralis biopsies was determined. During 10-days BR, we observed no significant fluctuation levels of irisin, myostatin, and sclerostin. Two days after BR (R+2), irisin serum levels significantly decreased while myostatin, sclerostin, and haptoglobin were significantly increased compared with BR0. Gene expression of myokines, inflammatory molecules, transcription factors, and markers of muscle atrophy and senescence on muscle biopsies were not altered, suggesting that muscle metabolism of young, healthy subjects is able to adapt to the hypomobility condition during 10-day BR. However, when subjects were divided according to irisin serum levels at BR9, muscle ring finger-1 mRNA expression was significantly lower in subjects with higher irisin serum levels, suggesting that this myokine may prevent the triggering of muscle atrophy. Moreover, the negative correlation between p21 mRNA and irisin at BR9 indicated a possible inhibitory effect of the myokine on the senescence marker. In conclusion, irisin could be a prognostic marker of hypomobility-induced muscle atrophy, and its serum levels could protect against muscle deterioration by preventing and/or delaying the expression of atrophy and senescence cellular markers.
Assuntos
Atrofia Muscular , Humanos , MasculinoRESUMO
PURPOSE: We have previously shown that accelerated running on flat terrain is biomechanically equivalent to running uphill at a constant speed. This hypothesis was further investigated comparing the energy cost of running at a constant speed either uphill, or on flat terrain against an equivalent horizontal impeding force, mimicking acceleration. METHODS: Steady-state O2 consumption and the corresponding energy cost (per unit body mass and distance) were determined on 12 male subjects during treadmill running at speeds between 2.11 and 2.89 m/s: (i) on the level, (ii) uphill at 10 or 20% incline ( I ), or (iii) on the level against a horizontal traction force of 10 or 20% of the subject's body weight ( TF ). This allowed us to estimate the net efficiency ( n e t η ) of running against horizontal or vertical forces, as given by the ratio between the additional mechanical work output under TF , or the corresponding I condition, and the difference between the appropriate energy cost above that for running at constant speed on flat terrain. RESULTS: The n e t η values when running uphill ( I ) amount to 0.35-0.40, whereas those for running against an equivalent impeding force ( TF ) are about 10% greater (0.45-0.50), a fact that may be due to a greater recovery of elastic energy in the TF as compared to the I condition. CONCLUSION: Making allowance for these small differences, these data support the view of considering accelerated running on flat terrain biomechanically equivalent to running at a constant speed, up an equivalent slope.
RESUMO
BACKGROUND: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) affects the cardiovascular system. The current study investigated changes in heart rate (HR), blood pressure (BP), pulse wave velocity (PWV), and microcirculation in patients recovering from Coronavirus disease 2019 (COVID-19) infection. METHODOLOGY: Out of 43 initially contacted COVID-19 patients, 35 (30 males, 5 females; age: 60 ± 10 years; and body mass index (BMI): 31.8 ± 4.9) participated in this study. Participants were seen on two occasions after hospital discharge; the baseline measurements were collected, either on the day of hospital discharge if a negative PCR test was obtained, or on the 10th day after hospitalization if the PCR test was positive. The second measurements were done 60 days after hospitalization. The vascular measurements were performed using the VICORDER® device and a retinal blood vessel image analysis. RESULTS: A significant increase in systolic BP (SBP) (from 142 mmHg, SD: 15, to 150 mmHg, SD: 19, p = 0.041), reduction in HR (from 76 bpm, SD: 15, to 69 bpm, SD: 11, p = 0.001), and narrower central retinal vein equivalent (CRVE) (from 240.94 µm, SD: 16.05, to 198.05 µm, SD: 17.36, p = 0.013) were found. Furthermore, the trends of increasing PWV (from 11 m/s, SD: 3, to 12 m/s, SD: 3, p = 0.095) and decreasing CRAE (from 138.87 µm, SD: 12.19, to 136.77 µm, SD: 13.19, p = 0.068) were recorded. CONCLUSION: The present study investigated cardiovascular changes following COVID-19 infection at two-time points after hospital discharge (baseline measurements and 60 days post-hospitalization). Significant changes were found in systolic blood pressure, heart rate, and microvasculature indicating that vascular adaptations may be ongoing even weeks after hospitalization from COVID-19 infection. Future studies could involve conducting additional interim assessments during the active infection and post-infection periods.
Assuntos
COVID-19 , Hipertensão , Rigidez Vascular , Masculino , Feminino , Humanos , Pessoa de Meia-Idade , Idoso , Projetos Piloto , Análise de Onda de Pulso , Microcirculação , Rigidez Vascular/fisiologia , SARS-CoV-2 , Pressão Sanguínea/fisiologiaRESUMO
BACKGROUD: Sarcopenia is a common skeletal muscle syndrome that is common in older adults but can be mitigated by adequate and regular physical activity. The development and severity of sarcopenia is favored by several factors, the most influential of which are a sedentary lifestyle and physical inactivity. The aim of this observational longitudinal cohort study was to evaluate changes in sarcopenia parameters, based on the EWGSOP2 definition in a population of active older adults after eight years. It was hypothesized that selected active older adults would perform better on sarcopenia tests than the average population. METHODS: The 52 active older adults (22 men and 30 women, mean age: 68.4 ± 5.6 years at the time of their first evaluation) participated in the study at two time points eight-years apart. Three sarcopenia parameters were assessed at both time points: Muscle strength (handgrip test), skeletal muscle mass index, and physical performance (gait speed), these parameters were used to diagnose sarcop0enia according to the EWGSOP2 definition. Additional motor tests were also performed at follow-up measurements to assess participants' overall fitness. Participants self-reported physical activity and sedentary behavior using General Physical Activity Questionnaire at baseline and at follow-up measurements. RESULTS: In the first measurements we did not detect signs of sarcopenia in any individual, but after 8 years, we detected signs of sarcopenia in 7 participants. After eight years, we detected decline in ; muscle strength (-10.2%; p < .001), muscle mass index (-5.4%; p < .001), and physical performance measured with gait speed (-28.6%; p < .001). Similarly, self-reported physical activity and sedentary behavior declined, too (-25.0%; p = .030 and - 48.5%; p < .001, respectively). CONCLUSIONS: Despite expected lower scores on tests of sarcopenia parameters due to age-related decline, participants performed better on motor tests than reported in similar studies. Nevertheless, the prevalence of sarcopenia was consistent with most of the published literature. TRIAL REGISTRATION: The clinical trial protocol was registered on ClinicalTrials.gov, identifier: NCT04899531.
Assuntos
Sarcopenia , Masculino , Humanos , Feminino , Idoso , Pessoa de Meia-Idade , Sarcopenia/diagnóstico , Sarcopenia/epidemiologia , Estudos Longitudinais , Força da Mão/fisiologia , Força Muscular , Músculo Esquelético , PrevalênciaRESUMO
CONTEXT: Exercise-induced muscle damage (EIMD) is prevalent especially in sports and rehabilitation. It causes loss in skeletal muscle function and soreness. As there are no firm preventive strategies, we aimed to evaluate the preventive efficacy of nonthermal 448-kHz capacitive resistive monopolar radiofrequency (CRMRF) therapy after eccentric bouts of EIMD response in knee flexors. DESIGN: Twenty-nine healthy males (age: 25.2 [4.6] y) were randomized in control group (CG; n = 15) and experimental group (EG; n = 14) where EG followed 5 daily 448-kHz CRMRF therapies. All assessments were performed at baseline and post EIMD (EIMD + 1, EIMD + 2, EIMD + 5, and EIMD + 9 d). We measured tensiomyography of biceps femoris and semitendinosus to calculate contraction time, the maximal displacement and the radial velocity of contraction, unilateral isometric knee flexors maximal voluntary contraction torque, and rate of torque development in first 100 milliseconds. RESULTS: Maximal voluntary contraction torque and rate of torque development in first 100 milliseconds decreased more in CG than in EG and recovered only in EG. Biceps femoris contraction time increased only in CG (without recovery), whereas in semitendinosus contraction time increased in EG (only at EIMD + 1) and in CG (without recovery). In both muscles, tensiomyographic maximal displacement decreased in EG (in EIMD + 1 and EIMD + 2) and in CG (without recovery). Furthermore, in both muscles, radial velocity of contraction decreased in EG (from EIMD + 1 until EIMD + 5) and in CG (without recovery). CONCLUSION: The study shows beneficial effect of CRMRF therapy after inducing EIMD in skeletal muscle strength and contractile parameters in knee flexors.
Assuntos
Contração Muscular , Músculo Esquelético , Masculino , Humanos , Adulto , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Força Muscular , Contração Isométrica , Dor , Torque , Mialgia/prevenção & controleRESUMO
The age-related decline in muscle function, particularly muscle power, is associated with increased risk of important clinical outcomes. Physical activity is an important determinant of muscle function, and different types of physical activity e.g. power-based versus endurance-based exercise appear to have differential effects on muscle power. Cross-sectional studies suggest that participation in power-based exercise is associated with greater muscle power across adulthood but this has not been investigated longitudinally. We recruited eighty-nine male and female power and endurance master athletes (sprint and distance runners respectively, baseline age 35-90y). Using jumping mechanography, we measured lower limb muscle function during a vertical jump including at least two testing sessions longitudinally over 4.5 ± 2.4y. We examined effects of time, discipline (power/endurance) and sex in addition to two- and three-way interactions using linear mixed-effects models. Peak relative power, relative force and jump height, but not Esslingen Fitness Index (indicating peak power relative to sex and age-matched reference data) declined with time. Peak power, force, height and EFI were greater in power than endurance athletes. There were no sex, discipline or sex*discipline interactions with time for any variable, suggesting that changes were similar over time for athletes of both sexes and disciplines. Advantages in lower limb muscle function in power athletes were maintained with time, in line with previous cross-sectional studies. These results suggest that improvements in lower limb function in less active older individuals following power-based training persist with continued adherence, although this requires further investigation in interventional studies.
Assuntos
Envelhecimento , Radioisótopos de Ítrio , Adulto , Idoso , Idoso de 80 Anos ou mais , Atletas , Estudos Transversais , Feminino , Humanos , Estudos Longitudinais , Extremidade Inferior , Masculino , Pessoa de Meia-Idade , Músculos , Resistência FísicaRESUMO
OBJECTIVES: This study evaluates the effect of post-activation potentiation (PAP) after 5x5s maximal voluntary isometric contractions (activation stimulus, AS) on tensiomyography (TMG) and torque twitch contractile parameters of vastus lateralis (VL) and medialis (VM), respectively. Further, we validated the decomposition of TMG response to separate responses of three fiber types. METHODS: 15 healthy individuals participated in this study (40% women; age 19±2.3 years). A decomposition of VL TMG response was done after optimal fitting of three exponential curves. RESULTS: We found main effects in contraction time (Tc) for muscle, method and time. Furthermore, we found interactions between muscle*method, method*time and muscle*method*time. Compared to PRE AS, we found shorter TMG Tc in VL and VM during the first two minutes after AS. Torque Tc remained unchanged in VL, while it increased in VM within 30 seconds after AS. A decomposition of VL TMG response confirmed PAP effects being present only in decomposed type IIb muscle fibers. CONCLUSION: The TMG is a sensitive method to detect PAP effects with a sensor mounted directly above the muscle belly. After the decomposition of the TMG signal to three separate muscle fiber phenotypes, we provided a non-invasive insight in the contribution of each muscle fiber phenotype to the PAP of the whole muscle.
Assuntos
Contração Isométrica , Contração Muscular , Eletromiografia , Feminino , Humanos , Contração Isométrica/fisiologia , Masculino , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , TorqueRESUMO
BACKGROUND: The COVID-19 pandemic situation with the lockdown of public life caused serious changes in people's everyday practices. The study evaluates the differences between Slovenia and Italy in health-related everyday practices induced by the restrictive measures during first wave of the COVID-19 pandemic. METHODS: The cross-sectional cohort study examined changes through an online survey conducted in nine European countries from April 15-28, 2020. The survey included questions from a simple activity inventory questionnaire (SIMPAQ), the European Health Interview Survey, and some other questions. To compare difference in changes between European countries we examined Italy with severe and its neighbour country Slovenia with low incidence and victims of COVID-19 epidemic. 956 valid responses from Italy (N = 511; 50% males) and Slovenia (N = 445; 26% males) were investigated. RESULTS: During the survey, there was a 4.7-fold higher incidence and 12.1-fold more deaths (per 100,000) in Italy than in Slovenia. Barring periods and measures were similar, the latter more stringent in Italy. We found more changes in Italy than in Slovenia: physical inactivity increased (Italy: + 65% vs. Slovenia: + 21%; p < 0.001), walking time decreased (Italy: -68% vs. Slovenia: -4.4%; p < 0.001); physical work increased by 38% in Slovenia (p < 0.001), and recreation time decreased by 37% in Italy (p < 0.001). Italians reported a decrease in quality of general health, fitness level, psychological well-being, quality of life and care for own health (p < 0.001); Slovenians showed a decline in psychological well-being and quality of life (p < 0.001) but generally had a higher concern for their own health (p = 0.005). In pooled participants, changes in eating habits (meal size and consumption of unhealthy food), age and physical inactivity were positively correlated with increases in body mass, while changes in general well-being and concern for health were negatively correlated. CONCLUSION: The study shows that the negative impact of COVID -19 measures is greater in Italy where the pandemic COVID -19 was more prevalent than in Slovenia with low prevalence. Additional consideration should be given to the negative impact of COVID-19 measures on some health-related lifestyle variables when implementing further measures to mitigate the COVID-19 pandemic.
Assuntos
COVID-19 , Pandemias , Controle de Doenças Transmissíveis , Estudos Transversais , Feminino , Humanos , Itália/epidemiologia , Masculino , Qualidade de Vida , SARS-CoV-2 , Inquéritos e QuestionáriosRESUMO
In order to identify peripheral biomarkers of impaired oxidative metabolism during exercise following a 10-day bed rest, 10 males performed an incremental exercise (to determine peak pulmonary VÌO2 (VÌO2 p)) and moderate-intensity exercises, before (PRE) and after (POST) bed rest. Blood flow response was evaluated in the common femoral artery by Eco-Doppler during 1 min of passive leg movements (PLM). The intramuscular matching between O2 delivery and O2 utilization was evaluated by near-infrared spectroscopy (NIRS). Mitochondrial respiration was evaluated ex vivo by high-resolution respirometry in isolated muscle fibres, and in vivo by NIRS by the evaluation of skeletal muscle VÌO2 (VÌO2 m) recovery kinetics. Resting VÌO2 m was estimated by NIRS. Peak VÌO2 p was lower in POST vs. PRE. The area under the blood flow vs. time curve during PLM was smaller (P = 0.03) in POST (274 ± 233 mL) vs. PRE (427 ± 291). An increased (P = 0.03) overshoot of muscle deoxygenation during a metabolic transition was identified in POST. Skeletal muscle citrate synthase activity was not different (P = 0.11) in POST (131 ± 16 nmol min-1 mg-1 ) vs. PRE (138 ± 19). Maximal ADP-stimulated mitochondrial respiration (66 ± 18 pmol s-1 mg-1 (POST) vs. 72 ± 14 (PRE), P = 0.41) was not affected by bed rest. Apparent Km for ADP sensitivity of mitochondrial respiration was reduced in POST vs. PRE (P = 0.04). The VÌO2 m recovery time constant was not different (P = 0.79) in POST (22 ± 6 s) vs. PRE (22 ± 6). Resting VÌO2 m was reduced by 25% in POST vs. PRE (P = 0.006). Microvascular-endothelial function was impaired following a 10-day bed rest, whereas mitochondrial mass and function (both in vivo and ex vivo) were unaffected or slightly enhanced. KEY POINTS: Ten days of horizontal bed rest impaired in vivo oxidative function during exercise. Microvascular impairments were identified by different methods. Mitochondrial mass and mitochondrial function (evaluated both in vivo and ex vivo) were unchanged or even improved (i.e. enhanced mitochondrial sensitivity to submaximal [ADP]). Resting muscle oxygen uptake was significantly lower following bed rest, suggesting that muscle catabolic processes induced by bed rest/inactivity are less energy-consuming than anabolic ones.
Assuntos
Repouso em Cama , Consumo de Oxigênio , Humanos , Masculino , Mitocôndrias/metabolismo , Músculo Esquelético/metabolismo , Estresse Oxidativo , RespiraçãoRESUMO
KEY POINTS: Few days of unloading are sufficient to induce a decline of skeletal muscle mass and function; notably, contractile force is lost at a faster rate than muscle mass. The reasons behind this disproportionate loss of muscle force are still poorly understood. We provide strong evidence of two mechanisms only hypothesized until now for the rapid muscle force loss in only 10 days of bed rest. Our results show that an initial neuromuscular junction instability, accompanied by alterations in the innervation status and impairment of single fibre sarcoplasmic reticulum function contribute to the loss of contractile force in front of a preserved myofibrillar function and central activation capacity. Early onset of neuromuscular junction instability and impairment in calcium dynamics involved in excitation-contraction coupling are proposed as eligible determinants to the greater decline in muscle force than in muscle size during unloading. ABSTRACT: Unloading induces rapid skeletal muscle atrophy and functional decline. Importantly, force is lost at a much higher rate than muscle mass. We aimed to investigate the early determinants of the disproportionate loss of force compared to that of muscle mass in response to unloading. Ten young participants underwent 10 days of bed rest (BR). At baseline (BR0) and at 10 days (BR10), quadriceps femoris (QF) volume (VOL) and isometric maximum voluntary contraction (MVC) were assessed. At BR0 and BR10 blood samples and biopsies of vastus lateralis (VL) muscle were collected. Neuromuscular junction (NMJ) stability and myofibre innervation status were assessed, together with single fibre mechanical properties and sarcoplasmic reticulum (SR) calcium handling. From BR0 to BR10, QFVOL and MVC decreased by 5.2% (P = 0.003) and 14.3% (P < 0.001), respectively. Initial and partial denervation was detected from increased neural cell adhesion molecule (NCAM)-positive myofibres at BR10 compared with BR0 (+3.4%, P = 0.016). NMJ instability was further inferred from increased C-terminal agrin fragment concentration in serum (+19.2% at BR10, P = 0.031). Fast fibre cross-sectional area (CSA) showed a trend to decrease by 15% (P = 0.055) at BR10, while single fibre maximal tension (force/CSA) was unchanged. However, at BR10 SR Ca2+ release in response to caffeine decreased by 35.1% (P < 0.002) and 30.2% (P < 0.001) in fast and slow fibres, respectively, pointing to an impaired excitation-contraction coupling. These findings support the view that the early onset of NMJ instability and impairment in SR function are eligible mechanisms contributing to the greater decline in muscle force than in muscle size during unloading.
Assuntos
Cálcio , Retículo Sarcoplasmático , Humanos , Contração Muscular , Músculo Esquelético , Junção Neuromuscular , Músculo QuadrícepsRESUMO
Space analogs, such as bed rest, are used to reproduce microgravity-induced morphological and physiological changes and can be used as clinical models of prolonged inactivity. Nevertheless, nonuniform decreases in muscle mass and function have been frequently reported, and peripheral nerve adaptations have been poorly studied, although some of these mechanisms may be explained. Ten young healthy males (18-33 yr) underwent 10 days of horizontal bed rest. Peripheral neurophysiological assessments were performed bilaterally for the dominant (DL) and nondominant upper and lower limbs (N-DL) on the 1st and 10th day of bed rest, including ultrasound of the median, deep peroneal nerve (DPN), and common fibular nerve (CFN) , as well as a complete nerve conduction study (NCS) of the upper and lower limbs. Consistently, reduced F waves, suggesting peripheral nerve dysfunction, of both the peroneal (DL: P = 0.005, N-DL: P = 0.013) and tibial nerves (DL: P = 0.037, N-DL: P = 0.005) were found bilaterally, whereas no changes were observed in nerve ultrasound or other parameters of the NCS of both the upper and lower limbs. In these young healthy males, only the F waves, known to respond to postural changes, were significantly affected by short-term bed rest. These preliminary results suggest that during simulated microgravity, most changes occur at the muscle or central nervous system level. Since the assessment of F waves is common in clinical neurophysiological examinations, caution should be used when testing individuals after prolonged immobility.
Assuntos
Repouso em Cama , Extremidades/inervação , Sistema Nervoso Periférico/fisiologia , Simulação de Ausência de Peso , Adaptação Fisiológica , Adolescente , Adulto , Voluntários Saudáveis , Humanos , Imageamento por Ressonância Magnética , Masculino , Condução Nervosa , Exame Neurológico , Sistema Nervoso Periférico/diagnóstico por imagem , Decúbito Dorsal , Fatores de Tempo , Ultrassonografia , Adulto JovemRESUMO
OBJECTIVES: Tensiomyography (TMG) derived contraction time (Tc) and amplitude (Dm) are related to muscle fibre composition and to muscle atrophy/tone, respectively. However, the link between mobility and TMG-derived skeletal muscle contractile properties in older persons is unknown. The aim of the study was to correlate lower limb skeletal muscle contractile properties with balance and mobility measures in senior female residents of retirement homes in Austria. METHODS: Twenty-eight female participants (aged from 67-99 years) were included in measurements of contractile properties (TMG) of four skeletal muscles: vastus lateralis, vastus medialis, biceps femoris and gastrocnemius medialis. Their balance and mobility performance was measured using a timed up and go test (TUG). RESULTS: Time needed to complete TUG is negatively correlated to biceps femoris (r= -0.490; p= 0.008), vastus lateralis (r= -0.414; p=0.028) and vastus medialis (r= -0.353; p=0.066) Dm and positively correlated to vastus lateralis Tc (r=0.456; p=0.015). Overall, vastus lateralis Tc and vastus medialis Dm explained 37% of TUG time variance. CONCLUSIONS: Our study demonstrates that TMG-derived quadriceps muscle contractile parameters are correlated with the balance and mobility function in female nursing home residents.
Assuntos
Músculo Esquelético , Equilíbrio Postural , Idoso , Idoso de 80 Anos ou mais , Eletromiografia , Feminino , Humanos , Contração Muscular , Casas de Saúde , Músculo Quadríceps , Estudos de Tempo e MovimentoRESUMO
Frailty and falls are a major public health problem in older adults. Muscle weakness of the lower and upper extremities are risk factors for any, as well as recurrent falls including injuries and fractures. While the Timed Up-and-Go (TUG) test is often used to identify frail members and fallers, tensiomyography (TMG) can be used as a non-invasive tool to assess the function of skeletal muscles. In a clinical study, we evaluated the correlation between the TMG parameters of the skeletal muscle contraction of 23 elderly participants (22 f, age 86.74 ± 7.88) and distance-based TUG test subtask times. TUG tests were recorded with an ultrasonic-based device. The sit-up and walking phases were significantly correlated to the contraction and delay time of the muscle vastus medialis (ρ = 0.55-0.80, p < 0.01). In addition, the delay time of the muscles vastus medialis (ρ = 0.45, p = 0.03) and gastrocnemius medialis (ρ = -0.44, p = 0.04) correlated to the sit-down phase. The maximal radial displacements of the biceps femoris showed significant correlations with the walk-forward times (ρ = -0.47, p = 0.021) and back (ρ = -0.43, p = 0.04). The association of TUG subtasks to muscle contractile parameters, therefore, could be utilized as a measure to improve the monitoring of elderly people's physical ability in general and during rehabilitation after a fall in particular. TUG test subtask measurements may be used as a proxy to monitor muscle properties in rehabilitation after long hospital stays and injuries or for fall prevention.
Assuntos
Fragilidade , Contração Muscular , Idoso , Idoso de 80 Anos ou mais , Humanos , Músculo Esquelético , Músculo Quadríceps , CaminhadaRESUMO
OBJECTIVE: This study aimed to evaluate changes in i) muscle contractile properties of both lower extremities by using tensiomyography (TMG); ii) patients' physical function, and iii) electromechanical efficiency (EME) of the gastrocnemius medialis muscle in total knee arthroplasty (TKA) patients from before to one-month after TKA. METHODS: Twenty-six patients scheduled for TKA were included. RESULTS: The significant muscle*time interaction was found for sustain time and maximal radial displacement (Dm) (η2≥0.219) only, whereas time*leg interaction was found for time delay and Dm (η2≥0.254) only. Post hoc analysis showed a significant decrease of Dm of vastus medialis and increase in contraction time (Tc) of both the vastus lateralis and rectus femoris muscles of the involved leg, respectively. Furthermore, reduction of knee extensors (-55.4%) and flexors (-22.2%) strength, timed up and go (-26.9%), 30s chair stand (-28.9%) and EME (-38.2%) was observed. CONCLUSION: TKA treatment altered physical function as well as contractile properties of the main skeletal muscles surrounding the involved joint in the early period after surgery; however, alterations showed to be both limb and muscle-specific. This might provide clinicians and physiotherapist with additional information on how to adapt rehabilitation to the needs of an individual patient.
Assuntos
Artroplastia do Joelho , Articulação do Joelho/fisiologia , Força Muscular/fisiologia , Músculo Esquelético/fisiologia , Idoso , Idoso de 80 Anos ou mais , Artroplastia do Joelho/efeitos adversos , Artroplastia do Joelho/reabilitação , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
The aging-related loss of muscle mass is thought to be partly attributable to motor neuron loss and motor unit remodeling that result in fiber type grouping. We examined fiber type grouping in 19- to 85-year-old athletes and non-athletes and evaluated to which extent any observed grouping is explained by the fiber type composition of the muscle. Since regular physical activity may stimulate reinnervation, we hypothesized that fiber groups are larger in master athletes than in age-matched non-athletes. Fiber type grouping was assessed in m. vastus lateralis biopsies from 22 young (19-27 years) and 35 healthy older (66-82 years) non-athletes, and 14 young (20-29 years), 51 middle-aged (38-65 years), and 31 older (66-85 years) athletes. An "enclosed fiber" was any muscle fiber of a particular type surrounded by fibers of the same type only. A fiber type group was defined as a group of fibers with at least one enclosed fiber. Only type II fiber cross-sectional area (FCSA) showed an age-related decline that was greater in athletes (P < .001) than in non-athletes (P = .012). There was no significant age-related effect on fiber group size or fiber group number in athletes or non-athletes, and the observed grouping was similar to that expected from the fiber type composition. At face value, these observations do 1) neither show evidence for an age-related loss and remodeling of motor units nor 2) improved reinnervation with regular physical activity, but 3) histological examination may not reveal the full extent of aging-related motor unit remodeling.
Assuntos
Envelhecimento/fisiologia , Fibras Musculares de Contração Rápida/fisiologia , Fibras Musculares de Contração Lenta/fisiologia , Esportes/fisiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Biópsia , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neurônios Motores/fisiologia , Fibras Musculares de Contração Rápida/citologia , Fibras Musculares de Contração Lenta/citologia , Músculo Quadríceps/anatomia & histologia , Músculo Quadríceps/inervação , Músculo Quadríceps/fisiologia , Adulto JovemRESUMO
BACKGROUND: The extreme social circumstances caused by declared COVID-19 pandemic deeply intervene people's everyday life and should not be neglected but seen through the view of social reality pinpointing the 'ordinary' people. In this article, authors explored basic segments of everyday and their subjective perception to what extent sleeping habits, physical inactivity, physical activity, nutritional habits and smoking have changed. METHODS: The online survey was conducted in nine European countries (Bosnia and Herzegovina, Croatia, Greece, Kosovo*, Italy, Serbia, Slovakia, Slovenia and Spain) in 4108 participants, aged 15-82 years. The survey took place 30-40 days after World Health Organization declared COVID-19 pandemic state, from 15 April to 3 May 2020. RESULTS: The results have shown 30 min longer sleeping time, 50% longer physical inactivity time, 65% longer screen time, 43% shorter walking time, 24% shorter sport time and 37% longer physical work time. Additionally, body mass gains (0.3 kg) could be explained in 20.6% with meals sizes, unhealthy food consumption, screen time and sport time. Further, respondents reported more regular meals (44%) and healthier meals with less alcohol consumption and less smoking, which have been positive outcomes of home confinement. CONCLUSION: The findings draw attention to negative changes in everyday praxis (inactivity, body mass gain) after such a short period. Because of possible risk to population's health (especially of countries such as Italy and Spain with serious threat and more stringent measures), findings enable development of recommendations for maintaining healthy lifestyle habits with minimal negative health consequences in similar pandemic circumstances.
Assuntos
COVID-19/epidemiologia , Comportamentos Relacionados com a Saúde , Estilo de Vida , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Europa (Continente)/epidemiologia , Exercício Físico , Comportamento Alimentar , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pandemias , SARS-CoV-2 , Tempo de Tela , Sono , Fumar/epidemiologia , Adulto JovemRESUMO
Gutiérrez-Vargas, R, Martín-Rodríguez, S, Sánchez-Ureña, B, Rodríguez-Montero, A, Salas-Cabrera, J, Gutiérrez-Vargas, JC, Simunic, B, and Rojas-Valverde, D. Biochemical and muscle mechanical postmarathon changes in hot and humid conditions. J Strength Cond Res 34(3): 847-856, 2020-The aim of this study was to compare biochemical changes and mechanical changes in the lower-limb muscles before and after a marathon race in hot and humid conditions. Eighteen healthy runners participated in a marathon at between 28 and 34° C and 81% humidity in Costa Rica. Serum magnesium (Mg), creatine phosphokinase (CPK), lactate dehydrogenase, and hematocrit (HCT) were measured before and after the marathon. Tensiomyography measurements from the rectus femoris (RF) and vastus medialis, muscle displacement (Dm), contraction time (Tc), and velocities of contraction to 10 and 90% of Dm (V10 and V90) were obtained before and after the marathon. Postrace measurements showed a 544% increase in CPK (t(17): -6.925, p < 0.01), a 16% increase in HCT (t(17): -7.466, p < 0.01), a 29% decrease in Mg (t(17): 3.91, p = 0.001), a 2% decrease in body mass (t(17): 4.162, p = 0.001), a 4% increase in Tc of the RF (t(17): -2.588, p = 0.019), and a 12% increase in Dm of the RF (t(17): -2.131, p < 0.048) compared with prerace measurements. No significant biochemical or mechanical differences were found between runners in terms of their finish times. These findings showed that completing a marathon in hot and humid conditions induced a significant reduction in lower-limb muscle stiffness, body mass, and Mg, and increased neuromuscular fatigue, CPK, and HCT, because of muscle damage and dehydration. Knowledge of the effects of heat and humidity may be of value for coaches and sports medicine practitioners in developing effective hydration and recovery protocols for marathon runners in these special conditions.
Assuntos
Temperatura Alta , Umidade , Extremidade Inferior/fisiologia , Músculo Esquelético/fisiologia , Corrida/fisiologia , Adulto , Costa Rica , Creatina Quinase/sangue , Feminino , Hematócrito , Humanos , L-Lactato Desidrogenase/sangue , Magnésio/sangue , Masculino , Pessoa de Meia-Idade , Músculo Quadríceps/fisiologia , Adulto JovemRESUMO
OBJECTIVE: This study investigated the effects of an 8-week plyometric training (PT) session on countermovement jump (CMJ) height, take-off velocity, and Tensiomyography (TMG) derived contractile parameters in seniors. METHODS: Twenty-three senior adults (age 66.7±5.2 years) were randomly divided into two groups: PLYO (n=11) and CTRL (n=12). Tensiomyography was measured in vastus lateralis (VL), biceps femoris (BF), tibialis anterior (TA), gastrocnemius medialis (GM), and lateralis (GL). Additionally, the electromechanical efficiency (EME) index was calculated in GM as a ratio between amplitudes of peak-to-peak M-wave and TMG (Dm) responses. Biochemical markers of muscle damage and inflammation were evaluated to provide indirect indices of exercise protocol safety. RESULTS: The main effect of time (for take-off velocity p=.023; ɳ2= .236) and group x time interactions (for CMJ, Tc (BF, GM), Dm (BF) and EME p<.05; ɳ2= .136 - .236) were observed. Post hoc analysis showed a significant increase in CMJ height and take-off velocity, namely by 14.2% (p=.001) and 8.2% (p=.01) in PLYO, respectively. Contraction time (Tc) decreased in BF -5.7% (p=.001) and GM -9.6% (p=.001). Dm decreased only in BF -20.8% (p=.001), while the EME index of the GM improved by 22.9% (p=.002). There were no differences between groups or assessment time points for C-reactive protein (p=.122). CONCLUSION: The present study clearly supports the application of supervised PT exercise in seniors, since explosive power, muscle contractility, and EME of the lower limbs were markedly improved after training.
Assuntos
Envelhecimento/fisiologia , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Exercício Pliométrico/métodos , Idoso , Feminino , Humanos , Masculino , Força Muscular/fisiologiaRESUMO
The purpose of this study was to create a valid and reliable assessment scale for the evaluation of three basic tennis strokes (forehand, backhand, serve) for 6-12-year-old tennis players, named the Tennis Rating Score for Children (TRSC). Altogether 60 players (21: forehand, 22: backhand, 17: serve) were video recorded (30 frames per second) while performing three main tennis strokes and later evaluated using the TRSC by five tennis trainers at Day 1 and Day 7. Agreement between days and raters was examined using the intraclass correlation coefficients (ICC). A Pearson's correlation was calculated to determine convergent validity (score related to participant's level of experience). The reliability between raters was very high for all three main strokes (ICCFOREHAND = 0.874; ICCBACKHAND = 0.877; ICCSERVE = 0.877). The intra-rater test-retests ICCs were also very high (ICCFOREHAND = 0.885; ICCBACKHAND = 0.891; ICCSERVE = 0.887). A large (rFOREHAND = 0.660) and very large (rBACKHAND = 0.730; rSERVE = 0.772) Pearson's correlations were found between all the ratings and the level of experience. The TRSC is shown to be highly reliable and valid when assessing technical skills in novice players, when compared to actual assessment from coaching experts; this tool may be helpful for tennis coaches to make a more objective diagnostic of the technical level of young tennis players.
Assuntos
Destreza Motora/fisiologia , Análise e Desempenho de Tarefas , Tênis/fisiologia , Fenômenos Biomecânicos , Criança , Humanos , Reprodutibilidade dos Testes , Gravação em VídeoRESUMO
KEY POINTS: Disuse in older adults can critically decrease lower limb muscle power, leading to compromised mobility and overall quality of life. We studied how muscle power and its determinants (muscle mass, single muscle fibre properties and motor control) adapted to 2 weeks of disuse and subsequent 2 weeks of physical training in young and older people. Disuse decreased lower limb muscle power in both groups; however, different adaptations in single muscle fibre properties and co-contraction of leg muscles were observed between young and older individuals. Six physical training sessions performed after disuse promoted the recovery of muscle mass and power. However, they were not sufficient to restore muscle power to pre-disuse values in older individuals, suggesting that further countermeasures are required to counteract the disuse-induced loss of muscle power in older adults. ABSTRACT: Disuse-induced loss of muscle power can be detrimental in older individuals, seriously impairing functional capacity. In this study, we examined the changes in maximal explosive power (MEP) of lower limbs induced by a 14-day disuse (bed-rest, BR) and a subsequent 14-day retraining, to assess whether the impact of disuse was greater in older than in young men, and to analyse the causes of such adaptations. Sixteen older adults (Old: 55-65 years) and seven Young (18-30 years) individuals participated in this study. In a subgroup of eight Old subjects, countermeasures based on cognitive training and protein supplementation were applied. MEP was measured with an explosive ergometer, muscle mass was determined by magnetic resonance, motor control was studied by EMG, and single muscle fibres were analysed in vastus lateralis biopsy samples. MEP was â¼33% lower in Old than in Young individuals, and remained significantly lower (-19%) when normalized by muscle volume. BR significantly affected MEP in Old (-15%) but not in Young. Retraining tended to increase MEP; however, this intervention was not sufficient to restore pre-BR values in Old. Ankle co-contraction increased after BR in Old only, and remained elevated after retraining (+30%). Significant atrophy occurred in slow fibres in Old, and in fast fibres in Young. After retraining, the recovery of muscle fibre thickness was partial. The proposed countermeasures were not sufficient to affect muscle mass and power. The greater impact of disuse and smaller retraining-induced recovery observed in Old highlight the importance of designing suitable rehabilitation protocols for older individuals.