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The validity of an accelerometric system (Myotest©) for assessing vertical jump height, vertical force and power, leg stiffness and reactivity index was examined. 20 healthy males performed 3×"5 hops in place", 3×"1 squat jump" and 3× "1 countermovement jump" during 2 test-retest sessions. The variables were simultaneously assessed using an accelerometer and a force platform at a frequency of 0.5 and 1 kHz, respectively. Both reliability and validity of the accelerometric system were studied. No significant differences between test and retest data were found (p < 0.05), showing a high level of reliability. Besides, moderate to high intraclass correlation coefficients (ICCs) (from 0.74 to 0.96) were obtained for all variables whereas weak to moderate ICCs (from 0.29 to 0.79) were obtained for force and power during the countermovement jump. With regards to validity, the difference between the two devices was not significant for 5 hops in place height (1.8 cm), force during squat (-1.4 N · kg(-1)) and countermovement (0.1 N · kg(-1)) jumps, leg stiffness (7.8 kN · m(-1)) and reactivity index (0.4). So, the measurements of these variables with this accelerometer are valid, which is not the case for the other variables. The main causes of non-validity for velocity, power and contact time assessment are temporal biases of the takeoff and touchdown moments detection.
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Sarcopenia is a pathology resulting from a progressive and severe loss of muscle mass, strength, and function in the course of aging, which has deleterious consequences on quality of life. Among the most widespread studies on the issue are those focused on the effect of different types of physical exercise on patients with sarcopenia. This randomized controlled study aimed to compare the effects of a whole-body vibration exercise (WBV) session on the inflammatory parameters of non-sarcopenic (NSG, n=22) and sarcopenic elderly (SG, n=22). NSG and SG participants were randomly divided into two protocols: intervention (squat with WBV) and control (squat without WBV). After a one-week washout period, participants switched protocols, so that everyone performed both protocols. Body composition was assessed by dual-energy radiological absorptiometry (DXA) and function through the six-minute walk test (6MWD) and Short Physical Performance Battery (SPPB). Plasma soluble tumor necrosis factor receptors (sTNFR) were determined by enzyme-linked immunosorbent assay (ELISA) and measured before and immediately after each protocol. After exercise with WBV, there was an increase in sTNFR2 levels in the NSG (P<0.01; d=-0.69 (-1.30; -0.08) and SG (P<0.01, d=-0.95 (-1.57; -0.32) groups. In conclusion, an acute session of WBV influenced sTNFr2 levels, with sarcopenic individuals showing a greater effect. This suggested that WBV had a more pronounced impact on sTNFr2 in those with loss of muscle strength and/or physical performance. Additionally, WBV is gaining recognition as an efficient strategy for those with persistent health issues.
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Sarcopenia , Vibração , Humanos , Sarcopenia/sangue , Sarcopenia/terapia , Vibração/uso terapêutico , Idoso , Masculino , Feminino , Receptores do Fator de Necrose Tumoral/sangue , Ensaio de Imunoadsorção Enzimática , Composição Corporal/fisiologia , Força Muscular/fisiologia , Absorciometria de Fóton , Terapia por Exercício/métodos , Resultado do Tratamento , Pessoa de Meia-Idade , Idoso de 80 Anos ou mais , Qualidade de VidaRESUMO
Objectives: To evaluate the association of physical and functional measures with sarcopenia in moderate chronic obstructive pulmonary disease (COPD) and to establish cutoff points for sarcopenia screening.Methods: The study included COPD with and without sarcopenia, of both sexes who were over 50 years old. Participants were assessed for lung function, body composition, grip strength, Short Physical Performance Battery (SPPB), 5-repetition, 10-repetition and 30-s sit-to-stand tests (5STS, 10STS, and 30STS, respectively). In addition, 6-min walking test, respiratory muscular strength, and physical activity level were tested.Results: The study had 35 participants, 24 men (68.6%) and moderate COPD (51.4%). COPD-sarcopenia showed lower values in lean mass, body fat and body mass alongside lower performance in 10 and 30 STS tests, SPPB and gait speed compared to non-sarcopenic group. The cutoff points with better sensitivity and specificity to identify sarcopenia were 10.88 and 34.14 s, 15 repetitions, and 10 points in the 5STS, 10STS, 30STS, and SPPB, respectively. The comparison of the receiver operating curves evidenced no differences between the functional tests. Only 30STS and SPPB showed acceptable discriminatory power.Conclusion: Functional tests, especially 30STS and SPPB, are simple and affordable tools for screening sarcopenia in COPD with moderate obstruction.
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Doença Pulmonar Obstrutiva Crônica , Sarcopenia , Teste de Esforço , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Força Muscular , Doença Pulmonar Obstrutiva Crônica/diagnóstico , Doença Pulmonar Obstrutiva Crônica/epidemiologia , Sarcopenia/diagnóstico , Sarcopenia/epidemiologia , Teste de CaminhadaRESUMO
The main purpose of this study was to assess the influence of the environmental temperature on both the aerodynamic flow evolving around the bicycle and cycling power output. The CFD method was used to investigate the detailed flow field around the cyclist/bicycle system for a constant speed of 11.1â¯m/s (40â¯km/h) without wind. In complement, a mathematical model was used to determine the temperature-dependent power output in the range [-10; 40⯰C]. The numerical investigation gives valuable information about the turbulent flow field in the cyclist's wake which evolves accordingly the surrounding temperature. A major result of this study is that the areas of overpressure upstream of the cyclist and of underpressure downstream of him are less extensive for a temperature of 40⯰C compared to -10⯰C. The results suggest that the aerodynamic braking effect of the bicycle is minimized when the air temperature is high, as a lower air density results in a reduction in drag on the cyclist. This study showed that the power required to maintain a constant speed is reduced when the temperature is high, the reason being a lower aerodynamic resistance.
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Ciclismo , Temperatura , Vento , Simulação por Computador , Humanos , HidrodinâmicaRESUMO
Abstract Sarcopenia is a pathology resulting from a progressive and severe loss of muscle mass, strength, and function in the course of aging, which has deleterious consequences on quality of life. Among the most widespread studies on the issue are those focused on the effect of different types of physical exercise on patients with sarcopenia. This randomized controlled study aimed to compare the effects of a whole-body vibration exercise (WBV) session on the inflammatory parameters of non-sarcopenic (NSG, n=22) and sarcopenic elderly (SG, n=22). NSG and SG participants were randomly divided into two protocols: intervention (squat with WBV) and control (squat without WBV). After a one-week washout period, participants switched protocols, so that everyone performed both protocols. Body composition was assessed by dual-energy radiological absorptiometry (DXA) and function through the six-minute walk test (6MWD) and Short Physical Performance Battery (SPPB). Plasma soluble tumor necrosis factor receptors (sTNFR) were determined by enzyme-linked immunosorbent assay (ELISA) and measured before and immediately after each protocol. After exercise with WBV, there was an increase in sTNFR2 levels in the NSG (P<0.01; d=-0.69 (-1.30; -0.08) and SG (P<0.01, d=-0.95 (-1.57; -0.32) groups. In conclusion, an acute session of WBV influenced sTNFr2 levels, with sarcopenic individuals showing a greater effect. This suggested that WBV had a more pronounced impact on sTNFr2 in those with loss of muscle strength and/or physical performance. Additionally, WBV is gaining recognition as an efficient strategy for those with persistent health issues.
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This study evaluated the effects of 6 weeks of whole-body vibration (WBV) exercise on flexibility and the rating of perceived exertion (RPE) in metabolic syndrome (MetS) individuals using 2 biomechanical conditions (fixed frequency [FF] and variable frequency [VF]). Nineteen MetS individuals were randomly allocated in FF-WBV (n = 9, 7 women and 2 men) and VF-WBV (n = 10, 8 women and 2 men) groups. Anterior trunk flexion (ATF) and RPE were determined before and after each session. The acute cumulative exposure effects were analyzed. The FF-WBV group was exposed to 5 Hz on a side alternating vibrating platform (SAVP), exposed to 10 and 50 seconds with the SAVP turned off. The VF-WBV group individuals were intermittently exposed (1 minute WBV exercise/1 minute rest) to 5 to 16 Hz, increased by 1 Hz per session and the peak-to-peak displacement (PPD) were 2.5, 5.0, and 7.5 mm. Regarding to ATF, significant improvements (P < .05) were observed in the in the acute (VF group) and cumulative intervention (FF and VF-WBV groups). The RPE significantly (P < .05) improved only in VF-WBV (cumulative intervention). In conclusion, WBV exercise improved the flexibility and decreased the RPE in MetS individuals. These findings suggest that WBV exercise can be incorporated into physical activities for MetS individuals.
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The aim of this numerical work is to analyze the effect of the position of the swimmer's head on the hydrodynamic performances in swimming. In this initial study, the problem was modeled as 2D and in steady hydrodynamic state. The geometry is generated by the CAD software CATIA and the numerical simulation is carried out by the use of the CFD Fluent code. The standard k-epsilon turbulence model is used with a specific wall law. Three positions of the head were studied, for a range of Reynolds numbers about 10(6). The obtained numerical results revealed that the position of the head had a noticeable effect on the hydrodynamic performances, strongly modifying the wake around the swimmer. The analysis of these results made it possible to propose an optimal position of the head of a swimmer in underwater swimming.
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Cabeça/fisiologia , Modelos Biológicos , Postura/fisiologia , Natação/fisiologia , Simulação por Computador , Feminino , Humanos , Reologia , Análise e Desempenho de TarefasRESUMO
Dizziness and balance disorders are frequent complaints in the general population. Vestibular rehabilitation exercises have been shown to be efficient in controlled studies, provided that a precise, individual diagnosis has previously been made. Depending on the pathology, a subject with a peripheral vestibular pathology can benefit from manoeuvres aiming at dislodging or repositioning otoliths, from non-specific muscles strengthening techniques, from techniques for vestibular-ocular or vestibular-cervical stabilisation of gaze, or from physical exercises aimed at strengthening proprioceptive afferents, inhibiting a sensory predominance, or improving spatial orientation and navigation. These analytical exercises should then be implemented in an ecological context in order to favour transfer to daily-living activities. These physical exercises can enable the development of compensation strategies following vestibular damage (habituation, adaptation and substitution).
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Doenças Vestibulares/reabilitação , Terapia por Exercício , Humanos , Exame Neurológico , Modalidades de Fisioterapia , Vertigem/diagnóstico , Vertigem/reabilitação , Doenças Vestibulares/diagnósticoRESUMO
The aerodynamic drag of three different time-trial cycling helmets was analyzed numerically for two different cyclist head positions. Computational Fluid Dynamics (CFD) methods were used to investigate the detailed airflow patterns around the cyclist for a constant velocity of 15â¯m/s without wind. The CFD simulations have focused on the aerodynamic drag effects in terms of wall shear stress maps and pressure coefficient distributions on the cyclist/helmet system. For a given head position, the helmet shape, by itself, obtained a weak effect on a cyclist's aerodynamic performance (<1.5%). However, by varying head position, a cyclist significantly influences aerodynamic performance; the maximum difference between both positions being about 6.4%. CFD results have also shown that both helmet shape and head position significantly influence drag forces, pressure and wall shear stress distributions on the whole cyclist's body due to the change in the near-wake behavior and in location of corresponding separation and attachment areas around the cyclist.
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Ciclismo , Dispositivos de Proteção da Cabeça , Hidrodinâmica , Fenômenos Biomecânicos , Humanos , Modelos Teóricos , Pressão , Resistência ao Cisalhamento , Software , Estresse Mecânico , VentoRESUMO
The aim of this study was to investigate how body thermal resistance between sexes evolves over time in the recovery period after a WBC session and to show how this parameter should be considered as a key parameter in WBC protocols. Eighteen healthy participants volunteered for the study (10 males and 8 females). Temperature (core and skin) were recorded pre- and post (immediately and every 5â¯min until 35â¯min post) exposure to a single bout of WBC (30â¯s at -60⯰C, 150â¯s at -110⯰C). From both core and skin temperatures a bio-heat transfer model was applied which led to the analytical formulation of the body thermal resistance. An unsteady behavior presenting a similar time-evolution trend in the body insulative response is shown for both females and males, possibly due to the vasodilatation process following an intense peripheral vasoconstriction during the extreme cold. Females present a 37% higher inner thermal resistance than males when reaching an asymptotical thermal state at rest due to a higher concentration of body fat percentage. Adiposity of tissues inherent in fat mass percentage appears to be a key parameter in the body thermal resistance to be taken into account in the definition of appropriate protocols for males and females. The conclusions of this preliminary study suggest that in order to achieve the same skin effects on temperature and consequently to cool efficiency tissues in the same way, the duration of cryotherapy protocols should be shorter when considering female compared to male.
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Crioterapia/métodos , Temperatura Alta , Fatores Sexuais , Temperatura Cutânea , Adiposidade , Adulto , Temperatura Baixa , Feminino , Voluntários Saudáveis , Frequência Cardíaca , Humanos , Masculino , Vasoconstrição , VasodilataçãoRESUMO
INTRODUCTION: Although fibromyalgia syndrome (SFM) affects 2-4 percent of adults, research has not identified a preferred therapeutic option for patients worldwide yet. Based on recent findings, it can be expected that whole body cryotherapy can improve health-reported quality of life by alleviating the symptoms of musculoskeletal pain and fatigue. OBJECTIVE: Our aim was to determine whether whole body cryotherapy only can result in improved perceived health and quality of life in fibromyalgia patients. METHODS: 24 patients with fibromyalgia diagnosis were randomized into 2 groups (n=11 in the whole body cryotherapy group, n=13 in the control group). In the whole body cryotherapy group, 10 sessions of whole body cryotherapy were performed (in addition to usual care) in a standard cryotherapy room over a duration of 8days. Subjects in the control group did not change anything in their everyday activities. Quality of life was assessed just before and one month after treatment. RESULTS: Compared with the control group, patients in the whole body cryotherapy group reported significantly improved for health-reported quality of life. These effects lasted for at least one month following intervention. CONCLUSION: Based on these findings, whole body cryotherapy can be recommended as an effective clinically adjuvant approach in the improvement of health-related quality of life in fibromyalgia patients.
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Crioterapia , Fibromialgia/terapia , Qualidade de Vida , HumanosRESUMO
BACKGROUND: The purpose of this case report is to highlight for the first time the way Medical Infrared Thermography can be a helpful tool to assist the surgeon in the surgical treatment of Hidradenitis Suppurativa inflammatory disease. METHODS: A 36-year-old man with a 7-year history of Hidradenitis Suppurativa presented inflammatory nodules in the left axilla area corresponding to Hurley stage II. Choice is made to surgically treat this patient using a wide excision protocol combined with a postoperative second intention healing. For the study purpose, an IR FLIR SC620 camera (FLIR Systems, Wilsonville, OR), having a high resolution pixel detector of 640×480 pixels for greater accuracy and higher resolution, has been used. RESULTS: For the first time in the literature, this case report on HS disease supports the idea that real-time medical infrared thermography may be helpful in establishing the true extent of disease preoperatively in the surgical room and in a similar manner, that this technique allows the surgeon to ensure all diseased lesions are removed during surgery. CONCLUSIONS: At least, medical infrared thermography seems to be a powerful tool to control the final wide surgical wound, in order to minimize recurrence risk of such a disease.
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The purpose of this study is to develop a numerical methodology based on real data from wind tunnel experiments to investigate the effect of the ski jumper's posture and speed on aerodynamic forces in a wide range of angles of attack. To improve our knowledge of the aerodynamic behavior of the ski jumper and his equipment during the early flight phase of the ski jump, we applied CFD methodology to evaluate the influence of angle of attack (α=14°, 21.5°, 29°, 36.5° and 44°) and speed (u=23, 26 and 29m/s) on aerodynamic forces in the situation of stable attitude of the ski jumper's body and skis. The standard k-ω turbulence model was used to investigate both the influence of the ski jumper's posture and speed on aerodynamic performance during the early flight phase. Numerical results show that the ski jumper's speed has very little impact on the lift and drag coefficients. Conversely, the lift and drag forces acting on the ski jumper's body during the early flight phase of the jump are strongly influenced by the variations of the angle of attack. The present results suggest that the greater the ski jumper's angle of inclination, with respect to the relative flow, the greater the pressure difference between the lower and upper parts of the skier. Further studies will focus on the dependency of the parameters with both the angle of attack α and the body-ski angle ß as control variables. It will be possible to test and optimize different ski jumping styles in different ski jumping hills and investigate different environmental conditions such as temperature, altitude or crosswinds.
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Esqui/fisiologia , Fenômenos Biomecânicos , Humanos , Hidrodinâmica , Postura , VentoRESUMO
This study deals with skin-friction drag analysis in underwater swimming. Although lower than profile drag, skin-friction drag remains significant and is the second and only other contribution to total drag in the case of underwater swimming. The question arises whether varying the thermal gradient between the underwater swimmer and the pool water may modify the surface shear stress distribution and the resulting skin-friction drag acting on a swimmer's body. As far as the authors are aware, such a question has not previously been addressed. Therefore, the purpose of this study was to quantify the effect of this thermal gradient by using the integral formalism applied to the forced convection theory. From a simplified model in a range of pool temperatures (20-30 degrees C) it was demonstrated that, whatever the swimming speeds, a 5.3% reduction in the skin-friction drag would occur with increasing average boundary-layer temperature provided that the flow remained laminar. However, as the majority of the flow is actually turbulent, a turbulent flow analysis leads to the major conclusion that friction drag is a function of underwater speed, leading to a possible 1.5% reduction for fast swimming speeds above 1m/s. Furthermore, simple correlations between the surface shear stress and resulting skin-friction drag are derived in terms of the boundary-layer temperature, which may be readily used in underwater swimming situations.
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Pele , Natação/fisiologia , Movimentos da Água , Simulação por Computador , Fricção , Humanos , Modelos Biológicos , Reologia , TemperaturaRESUMO
AIM: In this study, the role of arm motion in a drop jump was investigated in skilled and unskilled subjects. METHODS: Nine skilled volleyball players and 8 novice individuals performed a series of jumps from two different heights: 30 cm and 60 cm. Free and restricted arm motion were used to determine the effect of arm motion on the vertical jump. Participants were instructed to land on a force plate and jump as high as possible. The ground reaction force was measured with an AMTI force plate (500 Hz). The kinematics of the jumps was recorded with two digital cameras (50 Hz). RESULTS: The motion of the arms during the jumps was found to increase the jump height by 15% for the volleyball players and 12% for unskilled jumpers. Volleyball players performed better in the 60 cm than in 30 cm drop height (+8.5%). In the volleyball players, the peak vertical ground reaction force during take-off increased by 7%, the peak power increased by 10.6% while the peak impact force decreased by 6.3%. CONCLUSIONS: Skilled jumpers were found to have a better use of arm motion than novices in (i) increasing the vertical jump performance, (ii) controlling the balance of the body at take-off (iii) leaving the ground with an optimal body orientation.
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Extremidade Inferior/fisiologia , Esportes/fisiologia , Extremidade Superior/fisiologia , Adulto , Fenômenos Biomecânicos , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Destreza Motora/fisiologia , Movimento , Força Muscular/fisiologia , Fatores de Tempo , Gravação em VídeoRESUMO
This article establishes the basics of a theoretical model for the constitutive law that describes the skin temperature and thermolysis heat losses undergone by a subject during a session of whole-body cryotherapy (WBC). This study focuses on the few minutes during which the human body is subjected to a thermal shock. The relationship between skin temperature and thermolysis heat losses during this period is still unknown and have not yet been studied in the context of the whole human body. The analytical approach here is based on the hypothesis that the skin thermal shock during a WBC session can be thermally modelled by the sum of both radiative and free convective heat transfer functions. The validation of this scientific approach and the derivation of temporal evolution thermal laws, both on skin temperature and dissipated thermal power during the thermal shock open many avenues of large scale studies with the aim of proposing individualized cryotherapy protocols as well as protocols intended for target populations. Furthermore, this study shows quantitatively the substantial imbalance between human metabolism and thermolysis during WBC, the explanation of which remains an open question.
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Crioterapia/métodos , Fenômenos Fisiológicos da Pele , Temperatura Cutânea , Adulto , Superfície Corporal , Regulação da Temperatura Corporal , Temperatura Baixa , Humanos , Masculino , Modelos Teóricos , Projetos Piloto , Fatores de TempoRESUMO
AIM: The aim of this study was to compare the maximal power output (POpeak) and force-velocity relationships in sprint cycling obtained from a laboratory protocol and from a field test during actual cycling locomotion. METHODS: Seven male competitive cyclists performed 6 sprints (3 in the seated position and 3 in the standing position) on an ergo-trainer (Tacx, Netherlands) and 6 sprints during actual cycling locomotion in a gymnasium. The bicycle was equipped with the SRM Training System (Schoberer Rad Messtechnik, Germany) to measure (200 Hz) the power output (PO, W), the pedalling cadence (rpm), and the velocity (kmxh-1). From these measurements, the maximal force on the pedal (Fmax), the theoretical maximal force (Fo, N) and the theoretical maximal pedalling cadence (V0, rpm) were determined. During each sprint test the lateral bicycle oscillations were measured from a video analysis. RESULTS: During standing and seated sprints in the gymnasium, Fo and Fmax were significantly higher (p<0.05) compared with sprints on the ergo-trainer (+12% and +32%, respectively). The POpeak during sprints in seated and standing positions in the gymnasium was significantly (p<0.05) lower (-4%) and higher (+6%) respectively, compared with the ergo-trainer. For standing position in the gymnasium the kinematics analysis indicated a 24 degrees mean lateral bicycle oscillation compared with 0 degrees on the ergo trainer. CONCLUSION: The results of this study indicate that POpeak, Fo, and time to obtain POpeak were different between laboratory and actual cycling conditions. To obtain a valid estimation of the maximal power output, it is necessary to perform sprint tests during actual cycling locomotion. Thus, in the laboratory, it is advisable to use a cycle ergometer that enables natural lateral oscillations.
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Ciclismo/fisiologia , Ergometria/métodos , Adulto , Fenômenos Biomecânicos , Técnicas de Laboratório Clínico , Teste de Esforço , Humanos , Locomoção/fisiologia , Masculino , Consumo de Oxigênio/fisiologia , Resistência Física/fisiologiaRESUMO
A kinematic study allowed to define the three most propulsive positions during a butterfly swimming cycle, which were: the end of the external sweep, the end of the internal sweep and the end of thrust. These instantaneous positions were different for the ex-world champion Pankratov when compared to another swimmer. Using manikins and a drag-measuring device, we showed that the end of the internal sweep induced the highest drag values and that Pankratov may reduce energy expenditure by taking up a particular position during the end of the swimming cycle. These results point out the relations between swimming movements, passive drag and swimmers' performance.