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Fall injuries often occur on extension ladders. The extendable fly section of an extension ladder is typically closer to the user than the base section, though this design is minimally justified. This study investigates the effects of reversing the fly on foot placement, frictional requirements, adverse stepping events (repositioning the foot or kicking the rung), and user preferences. Participant foot placement was farther posterior (rung contacted nearer to toes) in the traditional ladder compared to the reversed fly condition during descent, with farther anterior foot placements during ascent. The reversed configuration had similar friction requirements during early/mid stance and significantly lower frictional requirements during late stance. Increased friction requirements during late stance were associated with farther anterior foot placement and further plantar flexed foot orientation. The reversed fly had 5 adverse stepping events versus 22 that occurred in the traditional configuration. Users typically preferred the reversed fly. These results suggest that a reversed extension ladder configuration offers potential benefits in reducing fall-related injuries that should motivate future research and development work.
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Accidentes por Caídas , Diseño de Equipo , Fricción , Humanos , Accidentes por Caídas/prevención & control , Masculino , Femenino , Adulto , Pie/fisiología , Fenómenos Biomecánicos , Seguridad , Adulto Joven , Subida de Escaleras/fisiologíaRESUMEN
Severe and fatal falls involving ladders commonly occur during transitions across the ladder and another support surface. Slipping is a common initiating event in ladder falls. This study characterized the friction requirements and body kinematics of descending roof-to-ladder transitions with and without a walk-through extension. Healthy adults who regularly climb ladders (n = 17) completed descending roof-to-ladder transitions, while foot-rung kinetics and body kinematics were recorded. The peak required coefficient of friction (RCOF) with respect to the plane of the shoe sole was calculated. The RCOF and body angle were calculated using their resultant values and projections in the frontal and sagittal planes. Foot angle was calculated in the sagittal plane. Repeated-measures ANOVA determined that compared to a walk-through ladder, a traditional ladder was associated with a higher RCOF in the medial-lateral (ML) direction (F1,16 = 190.07, p < 0.001) and a lower RCOF in the anterior-posterior (AP) direction (F1,16 = 11.02, p = 0.004), but had no significant relationship with the resultant RCOF (F1,16 = 0.098, p = 0.76). Spearman's rho tests performed across all testing configurations identified significant associations between foot angle and overall RCOF (rs = -0.724, p < 0.001), foot angle and AP RCOF (rs = -0.871, p < 0.001), and frontal plane body angle and ML RCOF (rs = 0.782, p < 0.001). Clustering in the data suggests that ladder attachments reduced frontal plane kinematics, which altered the direction of RCOF by reducing the medial-lateral component. These results have implications for designing rungs with good friction in multiple directions and the potential for body position monitoring in ladder tasks.
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This study investigates whether ladder climbing (LC), as a model of resistance exercise, can reverse whole-body and skeletal muscle deleterious metabolic and inflammatory effects of high-fat (HF) diet-induced obesity in mice. To accomplish this, Swiss mice were fed for 17 weeks either standard chow (SC) or an HF diet and then randomly assigned to remain sedentary or to undergo 8 weeks of LC training with progressive increases in resistance weight. Prior to beginning the exercise intervention, HF-fed animals displayed a 47% increase in body weight (BW) and impaired ability to clear blood glucose during an insulin tolerance test (ITT) when compared to SC animals. However, 8 weeks of LC significantly reduced BW, adipocyte size, as well as glycemia under fasting and during the ITT in HF-fed rats. LC also increased the phosphorylation of AktSer473 and AMPKThr172 and reduced tumor necrosis factor-alpha (TNF-α) and interleukin 1 beta (IL1-ß) contents in the quadriceps muscles of HF-fed mice. Additionally, LC reduced the gene expression of inflammatory markers and attenuated HF-diet-induced NADPH oxidase subunit gp91phox in skeletal muscles. LC training was effective in reducing adiposity and the content of inflammatory mediators in skeletal muscle and improved whole-body glycemic control in mice fed an HF diet.
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Resistencia a la Insulina , Entrenamiento de Fuerza , Tejido Adiposo/metabolismo , Animales , Glucemia/metabolismo , Dieta Alta en Grasa/efectos adversos , Humanos , Resistencia a la Insulina/fisiología , Ratones , Ratones Endogámicos C57BL , Músculo Esquelético/metabolismo , Obesidad/metabolismo , Obesidad/terapia , RatasRESUMEN
Dexamethasone (DEX) promotes proteolysis, which causes muscle atrophy. Muscle atrophy is connected to sarcopenia. We evaluated the effect of Curcuma longa L. water extract (CLW) on DEX-induced muscle atrophy. ICR mice were divided into three groups (eight mice per group) to investigate the capability of CLW in inhibiting muscle atrophy. The control group (Ex-CON) was administered distilled water (DW) by gavage and subjected to exercise; the muscle atrophy group (Ex-DEX) was administered DW by gavage, an injection of DEX (1 mg/kg body weight/day) intraperitoneally (IP), and subjected to exercise; and the treatment group (Ex-CLW) was administered CLW (1 g/kg body weight/day) by gavage, DEX IP injection, and subjected to exercise. Following the injection of DEX, the expression levels of myostatin, MuRF-1, and Atrogin-1 were increased. However, these expression levels were decreased in the Ex-CLW group, thereby leading to the conclusion that CLW inhibits muscle atrophy. ROS (that was overproduced by DEX) decreased antioxidant enzyme activity and increased malondialdehyde (MDA) levels, which led to muscle atrophy. When CLW was ingested, the antioxidant enzyme activities increased while the MDA levels decreased. These findings suggest that CLW could serve as a natural product for the prevention of muscle atrophy by modulating muscle atrophy-related genes and increasing antioxidant potential.
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The unfolded protein response (UPR) plays a pivotal role in some exercise training-induced physiological adaptation. Our aim was to evaluate the changes in the protein kinase R-like endoplasmic reticulum kinase (PERK) arm of the UPR and hypertrophy signaling pathway following 8 weeks of resistance training and creatine (Cr) supplementation in rats. Thirty-two adult male Wistar rats (8 weeks old) were randomly divided into 4 groups of 8: untrained + placebo (UN+P), resistance training + placebo (RT+P), untrained + Cr (UN+Cr), and resistance training + Cr (RT+Cr). Trained animals were submitted to the ladder-climbing exercise training 5 days per week for a total of 8 weeks. Cr supplementation groups received creatine diluted with 1.5 ml of 5% dextrose orally. The flexor hallucis longus (FHL) muscle was extracted 48 h after the last training session and used for western blotting. After training period, the RT+Cr and RT+P groups presented a significant increase in phosphorylated and phosphorylated/total ratio hypertrophy indices, phosphorylated and phosphorylated/total ratio PERK pathway proteins, and other downstream proteins of the PERK cascade compared with their untrained counterparts (P < 0.05). The increase in hypertrophy indices were higher but PERK pathway proteins were lower in the RT-Cr group than in the RT+P group (P < 0.05). There was no significant difference between the untrained groups (P > 0.05). Our study suggests that resistance training in addition to Cr supplementation modifies PERK pathway response and improves skeletal muscle hypertrophy.
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Creatina/administración & dosificación , Hipertrofia/genética , Músculo Esquelético/metabolismo , Condicionamiento Físico Animal/métodos , Procesamiento Proteico-Postraduccional , Respuesta de Proteína Desplegada , eIF-2 Quinasa/genética , Factor de Transcripción Activador 4/genética , Factor de Transcripción Activador 4/metabolismo , Adaptación Fisiológica , Animales , Suplementos Dietéticos , Factor 2 Eucariótico de Iniciación/genética , Factor 2 Eucariótico de Iniciación/metabolismo , Hipertrofia/etiología , Hipertrofia/metabolismo , Masculino , Fosforilación , Proteínas Proto-Oncogénicas c-akt/genética , Proteínas Proto-Oncogénicas c-akt/metabolismo , Ratas , Ratas Wistar , Entrenamiento de Fuerza , Transducción de Señal , Serina-Treonina Quinasas TOR/genética , Serina-Treonina Quinasas TOR/metabolismo , Factor de Transcripción CHOP/genética , Factor de Transcripción CHOP/metabolismo , eIF-2 Quinasa/metabolismoRESUMEN
Non-alcoholic fatty liver disease (NAFLD) is associated with obesity. The effect of resistance exercise without dietary restriction on the regulation of hepatic lipolytic factors is unclear. This study aimed to analyze the effects of aerobic and resistance exercise on hepatic lipolytic factors of obese mice. High-fat diet (HFD)-induced obese mice were divided into HFD + sedentary (HF), HFD + aerobic exercise, and HFD + resistance exercise groups. Exercise group mice were subjected to treadmill or ladder climbing exercise for 8 weeks. Fat mass and liver triglycerides were significantly decreased in both aerobic and resistance training groups. In the results of protein levels related to hepatic steatosis, HFD significantly increased liver cannabinoid receptor 1 and sterol-regulatory element binding protein 1 (SREBP-1). Both aerobic and resistance training significantly (p < 0.05) increased liver carnitine palmitoyltransferase-1, phosphor-AMP-activated protein kinase (p-AMPK), and p-AMPK/AMPK and decreased liver SREBP-1. However, the type of exercise did not exert any significant effects on these protein levels. Thus, resistance exercise, similarly to aerobic exercise, effectively regulated hepatic lipolytic factors of obese mice. Therefore, a sustainable type of exercise selected based on the fitness level, disease type, musculoskeletal disorder status, and preference of the patients is the best exercise intervention for alleviating NAFLD.
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Hígado , Enfermedad del Hígado Graso no Alcohólico , Entrenamiento de Fuerza , Animales , Dieta Alta en Grasa , Modelos Animales de Enfermedad , Ejercicio Físico , Humanos , Hígado/enzimología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Obesos , Enfermedad del Hígado Graso no Alcohólico/terapia , Entrenamiento de Fuerza/normasRESUMEN
Traditional guidance on ladder safety emphasizes training workers on the use of three points of contact. More recent guidance is to train workers to use three points of control. What is lacking is empirical information about what limb-movement patterns effectively support the use of three points of control. This project was conducted to establish a taxonomy of possible limb-movement patterns and a means for comparing relative safety. Prior to the experiment, a taxonomy of six possible limb-movement patterns was established. A sample of 20 undergraduate students performed four tasks each without any instructions on limb-movement pattern. The tasks were ascending and descending a straight ladder and a portable ladder, once each, while being videotaped. Out of 80 observed tasks, 59 of the subjects were using rungs rather than rails. Analysis of rung users identified the use of all six patterns. An innovative measure of safe performance was developed and used to compare the patterns. Statistical analysis did not find significant differences in the patterns based on the safety performance measure.
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Accidentes por Caídas , Movimiento , Fenómenos Biomecánicos , Humanos , SeguridadRESUMEN
This study investigated the ergonomics of three simulated 120 m vertical ladder ascents and differences between novice (NC) and experienced climbers (EC). Seven EC and 10 NC undertook three 120 m climbs; comprising of four 30 m climbs. Ascending 120 m was reported as a high physical demand, supported by high peak HRs (~173 b.min-1 across the three climbs) and VË O2 (~3.1 L.min-1 across the three climbs). Grip strength and endurance were significantly (p < 0.05) impaired by ascents. With multiple ascents, toe clearance was reduced (Climb 1 - 0.0515 m; Climb 3 - 0.046 m), and participants reached higher with their arms (shoulder angle: Climb 1 - 117°; Climb 3 - 136°). NC demonstrated less range of movement through the hips (NC - 46°; EC - 58°), and higher muscle activation in the upper body (NC - 60%; EC - 49%). Experience reduced cumulative climbing times (exercise + rest), whilst maintaining the same physiological demand as NC and maintained optimised movement patterns for longer.
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Ergonomía , Movimiento/fisiología , Competencia Profesional , Subida de Escaleras/fisiología , Análisis y Desempeño de Tareas , Adulto , Brazo/fisiología , Femenino , Fuerza de la Mano/fisiología , Frecuencia Cardíaca , Cadera/fisiología , Humanos , Industrias , Masculino , Ocupaciones , Resistencia Física/fisiología , Rango del Movimiento Articular/fisiología , Hombro/fisiologíaRESUMEN
Ladder slip and falls cause negative financial and health impacts due to their severity and frequency. However, frictional requirements of climbing, which presumably influence slip risk, are unknown. The purpose of this study was to quantify frictional requirements during climbing at different ladder angles. The required coefficient of friction (RCOF) was calculated during ladder climbing and assessed for three ladder angles (75.5°, 82.8°, and 90°). Data was collected from 10 participants at each angle. Kinetic data and kinematic data of the climber's shoe was collected and used to map friction and normal forces to the shoe. These forces were then used to calculate the RCOF. The RCOF and friction force at 90° was higher than at lower angles (75.5° and 82.8°). RCOF was correlated with shoe angle and body angle supporting both the relevance of shoe orientation and body position to slip risk. This study suggests that frictional requirements of ladder climbing are dependent on ladder angle, shoe orientation, and body angle.
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Fricción , Zapatos , Caminata/fisiología , Accidentes por Caídas , Adulto , Fenómenos Biomecánicos , Femenino , Humanos , Masculino , PosturaRESUMEN
Purpose. Physiologic demands of five common tasks in firefighting have been examined. Methods. Eight male volunteers, dressed up as smoke divers (+21 kg extra load), carried out the following tasks at constant pace for 5 min: walking at 1.4 m·s-1, walking (all walks at the same speed) while carrying a 10-kg ladder, walking carrying two hose packs of 16 kg together, walking carrying a 32-kg spreader tool and, finally, climbing up and down a ladder at a preset pace. A 5-min break separated each exercise. The heart rate, oxygen uptake and lung ventilation were measured continuously, and the blood lactate concentration was recorded after each task. Results. The end-exercise heart rate rose from 108 to 180 bpm from the first to last task, blood lactate concentration rose from 1 to 7 mmol·L-1, oxygen uptake rose from 19 to 48 ml·kg-1 min-1 and lung ventilation rose from 38 to 124 L·min-1. Discussion. Walking was an easy task even when dressed up as a smoke diver. Adding loads increased demands; ladder climbing taxed >90% of the subjects' aerobic power. Conclusions. The physiologic demands varied considerably between different tasks.
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Bomberos , Consumo de Oxígeno/fisiología , Esfuerzo Físico/fisiología , Adulto , Prueba de Esfuerzo/métodos , Frecuencia Cardíaca/fisiología , Humanos , Ácido Láctico/sangre , Masculino , Persona de Mediana Edad , Análisis y Desempeño de Tareas , Adulto JovenRESUMEN
BACKGROUND: To establish whether an organization has a valid Physical Employment Standard (PES), it is important to determine those aspects of the job that are critical to operational success. OBJECTIVE: To determine the tasks of the Offshore Wind Industry (OWI) and whether the ability to undertake these tasks is adequately assessed. METHODS: The task analysis was completed through: observations; the research team undertaking tasks; reviewing operational manuals; and focus groups. In addition, a review of existing PES for the OWI was completed to determine whether standards matched with the results of the task analysis. RESULTS: Five critical tasks were identified: transfer from the vessel to the Transition Piece; ascent of the internal ladder; manoeuvre through hatches; torque and tensioning; and hauling a casualty up the tower. With the exception of aerobic capacity, the physical components required by Technicians are not assessed by the current medical standards, nor are these assessments standardized across companies. CONCLUSIONS: The Job Task Analysis undertaken can be used to inform decisions regarding the physical fitness requirements (selection), assessments and training of Technicians, with a view to ensuring that they are physically capable of undertaking the critical tasks without undue risk of injury to themselves or others.
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Evaluación del Rendimiento de Empleados/normas , Empleo/normas , Selección de Personal/normas , Análisis y Desempeño de Tareas , Viento , Adulto , Toma de Decisiones en la Organización , Femenino , Humanos , Masculino , Persona de Mediana Edad , Aptitud Física , Centrales Eléctricas , Navíos , Reino Unido , Lugar de Trabajo , Adulto JovenRESUMEN
Effective treatments preventing brain neuroinflammatory diseases are lacking. Resistance-exercise training (RT) ameliorates mild cognitive impairment (MCI), a forerunner to neuroinflammatory diseases. However, few studies have addressed the molecular basis by which RT abates MCI. Thus experiments were performed to identify some molecular changes occurring in response to RT in young, female Wistar rats. To induce MCI, intraventricular lipopolysaccharide (LPS) injections were used to increase dentate gyrus inflammation, reflected by significantly increased TNF-α (~400%) and IL-1ß (~1,500%) mRNA (P < 0.0001) after 6 wk. Five days after LPS injections, half of LPS-injected rats performed RT by ladder climbing for 6 wk, 3 days/wk, whereas half remained without ladders. RT for 6 wk increased lean body mass percentage (P < 0.05), individual muscle masses (gastrocnemius and tibialis anterior) (P < 0.05), and maximum lifting capacity (P < 0.001). The RT group, compared with sedentary controls, had 1) ameliorated spatial learning deficits (P < 0.05), 2) increased dentate gyrus phosphorylation of IGF-1R, protein kinase B, and GSK-3ß proteins (P < 0.05), components of downstream IGF-1 signaling, and 3) increased dentate gyrus synaptic plasticity marker synapsin protein (P < 0.05). Two follow-up experiments (without LPS) characterized dentate gyrus signaling during short-term RT. Twenty-four hours following the third workout in a 1-wk training duration, phosphorylation of ERK1/2 and GSK-3ß proteins, as well as proliferation marker protein, PCNA, were significantly increased (P < 0.05). Similar changes did not occur in a separate group of rats following a single RT workout. Taken together, these data indicate that RT ameliorates LPS-induced MCI after RT, possibly mediated by increased IGF-1 signaling pathway components within the dentate gyrus. NEW & NOTEWORTHY The data suggest that resistance-exercise training restores cognitive deficits induced by lipopolysaccharides and can activate associated IGF-1 signaling in the dentate gyrus. Our data show, for the first time, that as few as three resistance-exercise workouts (spread over 1 wk) can activate IGF-1 downstream signaling and increase proliferation marker PCNA in the dentate gyrus.
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Disfunción Cognitiva/inducido químicamente , Disfunción Cognitiva/fisiopatología , Giro Dentado/fisiopatología , Lipopolisacáridos/farmacología , Condicionamiento Físico Animal/fisiología , Animales , Disfunción Cognitiva/metabolismo , Giro Dentado/metabolismo , Femenino , Glucógeno Sintasa Quinasa 3 beta/metabolismo , Hipocampo/metabolismo , Hipocampo/fisiopatología , Inflamación/metabolismo , Inflamación/fisiopatología , Factor I del Crecimiento Similar a la Insulina/metabolismo , Interleucina-1beta/metabolismo , Sistema de Señalización de MAP Quinasas/fisiología , Plasticidad Neuronal/fisiología , Proteínas Proto-Oncogénicas c-akt/metabolismo , Ratas , Ratas Wistar , Entrenamiento de Fuerza/instrumentación , Transducción de Señal/fisiología , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
BACKGROUND: A plurality of fatal falls to lower levels involve ladders. After a slip/misstep on a ladder, climbers use their upper and lower limbs to reestablish contact with the ladder. RESEARCH QUESTION: This study investigates the impact of upper body strength, hand placement and foot placement on fall severity after a ladder climbing perturbation. METHODS: Participants performed upper body strength tests (breakaway and grip strength) and climbed a vertical, fixed ladder while a misstep perturbation was applied under the foot. After the perturbation, three hand placement and two foot placement responses were generally observed. Common hand placement responses included the hand moving two rungs, one rung, or did not move to a different rung. Foot placement responses included at least one foot or no feet reestablished contact with the ladder rung(s). Fall severity was quantified by the peak harness force observed after the perturbation. RESULTS: Increased strength, reestablishing at least one foot on the ladder, and ascending (compared with descending) the ladder was associated with a reduction in fall severity. An interaction effect indicated that the impact of hand placement was altered by climbing direction. Moving the hand one rung during ascent and moving the hand two rungs during descent was associated with an increased fall severity. Cases where the hand decoupled from the ladder was associated with higher fall severity. Upper body strength assessed using a portable grip dynamometer was sufficient to predict fall severity. DISCUSSION: This study confirms the multifactor role of upper body strength, hand placement and foot placement in preventing falls from ladders. Furthermore, a portable dynamometer shows potential to screen for high-risk individuals. Results of this investigation may guide targeted interventions to prevent falls from ladders.
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Accidentes por Caídas/estadística & datos numéricos , Pie/fisiología , Mano/fisiología , Fuerza Muscular/fisiología , Equilibrio Postural/fisiología , Adolescente , Adulto , Femenino , Humanos , Masculino , Dinamómetro de Fuerza Muscular , Adulto JovenRESUMEN
This study aimed to assess whether modifying the pitch of a 75° ladder ergometer to vertical had a cardiorespiratory or psychophysical effect on climbing. Nine male participants climbed a ladder ergometer at 75° and subsequently at 90°, adjusted for an equivalent vertical climb rate, completing three climbing bouts at different vertical speeds. One participant dropped out being unable to complete the climb under the 90° condition. Each was monitored for heart rate (HR), VËO2 and rating of perceived exertion (RPE). Results showed vertical climbing induced higher VËO2 (mean increase 17.3%), higher HR (mean increase 15.8%), and higher RPE at all speeds and that moving from 75°to vertical exacerbates the effect of speed on the cardiorespiratory response to climbing. This may be explained by increased force production required to maintain balance in a vertical climbing position when the body's centre of mass is not above the feet.
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Ergometría/métodos , Subida de Escaleras/fisiología , Estudios Cruzados , Voluntarios Sanos , Frecuencia Cardíaca/fisiología , Humanos , Masculino , Consumo de Oxígeno/fisiología , Esfuerzo Físico/fisiología , Adulto JovenRESUMEN
Objective We examined the impacts of pulling task (breakaway and pull-down tasks at different postures), glove use, and their interaction on achievable downward pull forces from a ladder rung. Background Posture, glove use, and the type of pulling task are known to affect the achievable forces. However, a gap in the literature exists regarding how these factors affect achievable downward pulling forces, which are relevant to recovery from a perturbation during ladder climbing. Methods Forty subjects completed four downward pulling tasks (breakaway force; pull force at maximum height, shoulder height, and a middle height), using three glove conditions with varying coefficient of friction (COF) levels (cotton glove, low COF; bare hand, moderate COF; and latex-coated glove, high COF) with their dominant and nondominant hand. The outcome variable was the maximum force normalized to body weight. Results The highest forces were observed for the highest hand postures (breakaway and maximum height). Increased COF led to higher forces and had a larger effect on breakaway force than the other tasks. The dominant hand was associated with higher forces than the nondominant hand. Male subjects generated greater forces than female subjects, particularly for higher hand positions. Conclusion This study suggests that a higher hand position on the ladder, while avoiding low-friction gloves, may be effective for improving recovery from ladder perturbations. Application This study may guide preferred climbing strategies (particularly those that lead to a higher hand position) for improving recovery from a perturbation during ladder climbing.
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Fenómenos Biomecánicos/fisiología , Guantes Protectores , Mano/fisiología , Actividad Motora/fisiología , Postura/fisiología , Adulto , Femenino , Fricción , Humanos , MasculinoRESUMEN
The aim of this study is to investigate the effects of intermittent ladder-climbing exercise training on mitochondrial biogenesis and ER stress of the cardiac muscle in high fat diet-induced obese middle-aged rats. We induced obesity over 6 weeks of period in 40 male Sprague-Dawley rats around 50 weeks old, and were randomly divided into four experimental groups: chow, HFD, exercise+HFD, and exercise+chow. The exercising groups underwent high-intensity intermittent training using a ladder-climbing and weight exercise 3 days/week for a total of 8 weeks. High-fat diet and concurrent exercise resulted in no significant reduction in body weight but caused a significant reduction in visceral fat weight (p<0.05). Expression of PPARδ increased in the exercise groups and was significantly increased in the high-fat diet+exercise group (p<0.05). Among the ER stress-related proteins, the expression levels of p-PERK and CHOP, related to cardiac muscle damage, were significantly higher in the cardiac muscle of the high-fat diet group (p<0.05), and were significantly reduced by intermittent ladder-climbing exercise training (p<0.05). Specifically, this reduction was greater when the rats underwent exercise after switching back to the chow diet with a reduced caloric intake. Collectively, these results suggest that the combination of intermittent ladder-climbing exercise training and a reduced caloric intake can decrease the levels of ER stress-related proteins that contribute to cardiac muscle damage in obesity and aging. However, additional validation is required to understand the effects of these changes on mitochondrial biogenesis during exercise.
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Different from walking, ladder climbing requires four-limb coordination and more energy exertion for below-knee amputees (BKAs). We hypothesized that functional deficiency of a disabled limb shall be compensated by the other three intact limbs, showing an asymmetry pattern among limbs. Hand and foot forces of six below-knee amputees and six able-bodied people were collected. Hand, foot and hand/foot sum force variances between groups (non-BKA, intact side and prosthetic side) were carefully examined. Our hypothesis was validated that there is asymmetry between prosthetic and intact side. Results further showed that the ipsilateral hand of the prosthetic leg is stronger than the hand on the intact side, compensating weakness of the prosthetic leg. Effects of ladder rung separations and ladder slant on asymmetric force distribution of BKAs were evaluated, indicating that rung separation has a more significant interactive effect on hand/foot force of BKAs than ladder slant.
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Amputados , Pie/fisiopatología , Mano/fisiopatología , Locomoción/fisiología , Adulto , Miembros Artificiales , Fenómenos Biomecánicos , Humanos , Pierna , MasculinoRESUMEN
'Climb assist' claims to reduce strain when climbing ladders; however, no research has yet substantiated this. The purpose of this study was to assess the physiological and psychophysical effects of climb assist on 30 m ladder climbing at a minimum acceptable speed. Eight participants (six male and two female) climbed a 30 m ladder at 24 rungs per minute with and without climb assist, and were monitored for heart rate (HR), [Formula: see text]O2 and rate of perceived exertion (RPE). All three variables decreased significantly (p < 0.05) with climb assist with [Formula: see text]O2 decreasing by 22.5%, HR by 14.8% and RPE decreasing by a mean of 2.3 units on the 10-point Borg scale. When descending the ladder [Formula: see text]O2 decreased by a mean of 42% compared to that ascending. At the minimal acceptable climbing speed climb assist decreases the physiological strain on climbers, as demonstrated by reduced [Formula: see text]O2, HR and perceived exertion. Practitioner Summary: 'Climb assist' systems claim to reduce strain when climbing, however; no research has yet been published to substantiate this. A crossover study compared [Formula: see text]O2, HR and RPE at a minimal acceptable climbing speed with and without climb assist. Climb assist significantly reduced all variables confirming it reduces strain when climbing.
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Dispositivo Exoesqueleto , Esguinces y Distensiones/prevención & control , Subida de Escaleras/fisiología , Adulto , Estudios Cruzados , Femenino , Frecuencia Cardíaca/fisiología , Humanos , Masculino , Consumo de Oxígeno/fisiología , Esfuerzo Físico/fisiología , Esguinces y Distensiones/etiología , Esguinces y Distensiones/fisiopatologíaRESUMEN
The aim of this study is to investigate the effects of intermittent ladder-climbing exercise training on mitochondrial biogenesis and ER stress of the cardiac muscle in high fat diet-induced obese middle-aged rats. We induced obesity over 6 weeks of period in 40 male Sprague-Dawley rats around 50 weeks old, and were randomly divided into four experimental groups: chow, HFD, exercise+HFD, and exercise+chow. The exercising groups underwent high-intensity intermittent training using a ladder-climbing and weight exercise 3 days/week for a total of 8 weeks. High-fat diet and concurrent exercise resulted in no significant reduction in body weight but caused a significant reduction in visceral fat weight (p<0.05). Expression of PPARδ increased in the exercise groups and was significantly increased in the high-fat diet+exercise group (p<0.05). Among the ER stress-related proteins, the expression levels of p-PERK and CHOP, related to cardiac muscle damage, were significantly higher in the cardiac muscle of the high-fat diet group (p<0.05), and were significantly reduced by intermittent ladder-climbing exercise training (p<0.05). Specifically, this reduction was greater when the rats underwent exercise after switching back to the chow diet with a reduced caloric intake. Collectively, these results suggest that the combination of intermittent ladder-climbing exercise training and a reduced caloric intake can decrease the levels of ER stress-related proteins that contribute to cardiac muscle damage in obesity and aging. However, additional validation is required to understand the effects of these changes on mitochondrial biogenesis during exercise.
Asunto(s)
Animales , Humanos , Masculino , Ratas , Envejecimiento , Peso Corporal , Dieta , Dieta Alta en Grasa , Estrés del Retículo Endoplásmico , Retículo Endoplásmico , Ingestión de Energía , Grasa Intraabdominal , Miocardio , Obesidad , Biogénesis de Organelos , Ratas Sprague-DawleyRESUMEN
PURPOSE: The appropriate mode of exercise training for cancer cachexia is not well-established. Using the colon-26 (C26) mouse model of cancer cachexia, we defined and compared the skeletal muscle responses to aerobic and resistance training. METHODS: Twelve-month old Balb/c mice were initially assigned to control, aerobic training (AT; wheel running), or resistance training (RT; ladder climbing) (n=16-17/group). After 8weeks of training, half of each group was injected with C26 tumor cells, followed by 3 additional weeks of training. Body composition and neuromuscular function was evaluated pre- and post-training. Muscles were collected post-training and analyzed for fiber cross-sectional area (CSA), Akt-mTOR signaling, and expression of insulin-like growth factor-I (IGF-I) and myogenic regulatory factors. RESULTS: Total body mass decreased (p<0.05) in C26 (-8%), AT+C26 (-18%), and RT+C26 (-15%) but not control. Sensorimotor function declined (p<0.05) in control (-16%), C26 (-13%), and RT+C26 (-23%) but not AT+C26. Similarly, strength/body weight decreased (p<0.05) in control (-7%), C26 (-21%), and RT+C26 (-10%) but not AT+C26. Gastrocnemius mass/body weight tended to be greater in AT+C26 vs. C26 (+6%, p=0.09). Enlargement of the spleen was partially corrected in AT+C26 (-27% vs. C26, p<0.05). Fiber CSA was lower in all C26 groups vs. control (-32% to 46%, p<0.05); however, the effect size calculated from C26 and AT+C26 was large (+24%, d=1.04). Phosphorylated levels of mTOR in AT+C26 exceeded C26 (+32%, p<0.05). RT+C26 showed greater mRNA expression (p<0.05) of IGF-IEa (+79%) and myogenin (+126%) with a strong tendency for greater IGF-IEb (+127%, p=0.069) vs. CONCLUSIONS: Aerobic or resistance training was unable to prevent tumor-induced body weight loss. However, aerobic training may have preserved function, reduced the inflammatory response of the spleen, and marginally rescued muscle mass possibly through activation of mTOR. Aerobic training may therefore have therapeutic value for patients with cancer cachexia. In contrast, resistance training induced the expression of genes associated with muscle damage and repair. This gene response may be supportive of excessive stress generated by high resistance loading in a tumor-bearing state.