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Query: UMLS:C0015672 (fatigue)
 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Eight horses were exercised at speeds to produce 80% of maximal heart rates, on 4 occasions using a randomised block design, and girthed at tensions of approximately 5, 10, 15 or 20 kg using a standard canvas girth attached to a racing saddle. Tension was recorded continuously using an in-line load cell connected to a physiograph. Horses ran until fatigued on a treadmill inclined at 10% slope. Tensions were measured at peak inhalation (T/inh) and exhalation (T/exh), recorded at rest (rest) and during exercise (ex). Data were analysed by ANOVA and, in addition, least squares linear regression was performed to determine the relationship between distance travelled, time to fatigue and the recorded maximum tensions at inhalation and minimum tensions at exhalation. For T/inhrest, every increase in girth tension by 1 kg was associated with a reduction in distance to fatigue by 98.3 +/- 28.6 m and a corresponding reduction in run times of 0.24 +/- 0.07 min (P = 0.01). Results for T/exhrest were similar, with a reduction of mean +/- s.e. 81.3 +/- 26.9 m and 0.20 +/- 0.07 min per 1 kg increase in tension (P = 0.02). The mean distances to fatigue for the T/exhrest of 5, 10, 15 and 20 kg were 6624, 5812, 5268 and 5405 m respectively. These data indicate that distances to fatigue are similar once T/exhrest equals or exceeds 10 kg. Based on this study, resting girth tensions less than 10 kg are optimal for performance, but from our survey data, tensions exceeding this tension are typical for Thoroughbred racing in Victoria.
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PMID:Influence of girth strap tensions on athletic performance of racehorses. 1065 22

Six horses were randomly assigned to receive either frusemide (F) (0.5 mg/kg i.v.) or an equivalent volume of saline (S) i.v., 4 h prior to treadmill exercise. Horses were instrumented to enable measurement of heart rate (HR), systolic (SAP), mean (MAP), and diastolic (DAP) carotid arterial pressures, pulmonary artery pressure (PAP), central venous pressure (CVP), pulmonary arterial temperature (TEMP), blood gases, and cardiac output (CO). Plasma (PV) and blood volumes (BV) were measured using 2 injections of Evan's Blue dye. Baseline parameters were recorded while the horse stood quietly. Horses were then administered F or S. Four hours later, they were warmed up for 3 min at 4 m/s and then exercised to the point of fatigue at 115% VO2max. Horses were anaesthetised immediately following exercise by administration of detomidine (0.04 mg/kg bwt i.v.) followed 5 min later by tiletamine-zolazepam (1.25 mg/kg bwt i.v.). After transporting the horse to a recovery stall, anaesthesia was maintained with isoflurane in 100% O2. Data were analysed using a 2-way ANOVA with repeated measures with post hoc differences identified using the Student-Newman-Keul's procedure. Exercise was associated with increases in HR, SAP, MAP, DAP, PAP, CVP, TEMP, PCV, and BV, and decreases in PV, pH, arterial bicarbonate and base excess. Anaesthesia was associated with marked hypercapnia, a decrease in HR following detomidine administration, and persistent pulmonary hypertension despite carotid arterial pressure which returned to baseline. No effects attributable to F were identified at any time during the study.
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PMID:Effects of pre-exercise frusemide administration and post exercise anaesthesia on cardiopulmonary and acid-base parameters and blood and plasma volumes in horses exercised supramaximally to fatigue. 1065 46

This study evaluated the effects of pre-exercise frusemide administration and hypertonic saline (H) infusion during anaesthesia on arterial pH, blood gases and electrolytes in 6 Thoroughbred horses anaesthetised immediately post exercise. Horses received either frusemide (F) (0.5 mg/kg, i.v.) or a saline placebo (P) injection 4 h prior to treadmill exercise. Exercise consisted of a 3 min warm-up at 40% VO2max followed by exercise to fatigue. Detomidine (40 micrograms/kg, i.v.) was given within 5 min of stopping and followed 5 min later by zolazepam-tiletamine (1.25 mg/kg, i.v.) to induce anaesthesia. During maintenance of anaesthesia using isoflurane in O2, either isotonic saline solution (I) or 7.5% H (4 ml/kg, i.v.) was administered. Arterial blood was sampled at the following times: prior to (Pre-F/P) and 4 h after (Pre-ex) F or P administration, 1 min after fatigue (Fatigue), 5 min after induction of anaesthesia (Post-ind), and just prior to and 15, 30 and 60 min after beginning isoflurane (ISFL) anaesthesia. Arterial pH and blood gas tensions, pulmonary arterial blood temperature, plasma [lactate], total protein and plasma [Na+], [K+], and [Cl-] were measured. Data were analyzed using 2-way ANOVA for repeated measures (P < 0.05). There were significant differences over time for all variables except total protein. Plasma [Na+] increased at Fatigue compared to Pre-F/P or Pre-ex in all treatment groups. Plasma [Na+] and [Cl-] increased during ISFL anaesthesia compared to Pre-F/P and Pre-ex in horses given H. During ISFL anaesthesia, plasma [Cl-] decreased compared to Pre-F/P in Group F+I horses. We conclude that acid-base, blood gas, and electrolyte changes associated with F are unlikely to influence management of horses anaesthetised immediately following supramaximal exercise to fatigue. Hypertonic saline infusion may help restore plasma [Cl-] faster in hypochloraemic horses requiring anaesthesia immediately after strenuous exercise.
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PMID:Effect of frusemide and hypertonic saline on electrolytes during post exercise anaesthesia. 1065 95

The effects of sucrose and oil preloads were explicitly compared in a single-blind controlled trial using a between-subjects design. Eighty adult subjects (forty-three male, thirty-seven female) aged 18-50 years received at 11.00 hours one of four yoghurt preloads. All were 80 g low-fat, unsweetened yoghurt (188 kJ), containing additionally (1) saccharin (control, 23 kJ), or (2) 40 g sucrose (859 kJ), (3) 40 g maize oil (1569 kJ), (4) 20 g sucrose, 20 g maize oil (1213 kJ). Subjects were normal eaters and of normal weight (male mean weight: 68.8 (SD 3.2) kg, BMI 21.8 (SD 1.6) kg/m2; female mean weight: 53.7 (SD 5.1) kg, BMI 20.4 (SD 1.2) kg/m2). Food intake was measured with a food diary and mood with ten single Likert scales. ANOVA was conducted using preload type (saccharin, sucrose, oil, sucrose + oil), sex (male, female) and early v. late breakfast times as factors. Mood was analysed using the same design, with time of rating (immediate, 60 min, 120 min) as an additional factor. Men ate more after the saccharin preload than after the other preloads, but did not vary the time of their next solid food. Women increased the intermeal interval only after the oil preload, which also had the highest energy content value, but did not vary the energy content of their next solid food. The saccharin preload decreased rated tiredness at 2 h compared with the sucrose preload, possibly due to its lower energy content. The preloads containing sucrose or sucrose + oil increased calmness between 1 and 2 h afterwards, compared with the saccharin preload. It is concluded that both sucrose and oil increase the intermeal interval in men, but that women are less sensitive to preloading. The mood effects suggest that tiredness after carbohydrate at 2 h may in part be a decrease in rated energy compared with the increased rated energy found after a preload with low energy content. Carbohydrate may genuinely increase calmness. These effects apply to non-restrained eaters of normal weight.
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PMID:The effects of sucrose and maize oil on subsequent food intake and mood. 1069 Jan 60

The purpose of this study was to describe the patterns of cancer-related fatigue (CRF) and vigor in patients receiving chemotherapy or radiation therapy. Five studies that measured fatigue and vigor with the Profile of Mood States were used to describe the pattern of CRF and vigor during and after both types of treatment. Repeated-measures ANOVA was used to determine differences over time in each study. Results demonstrate different patterns of CRF for patients receiving chemotherapy and radiation therapy. Chemotherapy-related CRF peaks in the days after chemotherapy, whereas radiation therapy-related CRF gradually accumulates over the course of treatment. The CRF associated with both forms of treatment gradually declines over time. The prevalence, intensity, and persistence of CRF during treatment and for months after treatment is complete make this symptom one that cannot be ignored.
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PMID:Fatigue patterns observed in patients receiving chemotherapy and radiotherapy. 1070 72

The purpose of this study was to clarify the trends in the variation within the day, and between days, of subjective symptoms of fatigue (SSF) in the daily life of male students. A SSF questionnaire (54 items) with guaranteed validity and reliability was administered to 104, 15-16 year-old healthy students, 3 times a day, in the morning (about 08:50), mid-day (about 12:10) and afternoon (about 16:10) for 5 days from Monday to Friday. As the main statistical analysis, two-way (day and week) ANOVA and post-hoc t tests were used. The SSF questionnaire was considered to have very high reliability because Cronbach's alpha coefficients in each survey point of time were .967-.977. SSF complaints between days were low on the whole, but complaints of drowsiness were relatively high. The trends in variation of SSF between days were greater than those within the day. The trends in variation within the day were noticeable in complaints regarding drowsiness and loss of vigor. Complaints regarding languor became high from the middle of the week to the weekend. On the other hand, SSF complaints except for languor, were high at the beginning of the week, especially on Monday and became lower after Tuesday. There is a trend in variation within the day for symptoms regarding drowsiness and loss of vigor. The trend in variation between days was confirmed for many SSFs, and was noticeable as compared to those within the day. Complaints regarding languor were high on the weekend, and SSF complaints except for languor were high at the beginning of the week, especially on Monday.
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PMID:[Trends in variation within the day and between days of subjective symptoms of fatigue in adolescent males]. 1071 51

The purpose of this study was to delineate the contribution of increasing suture strands and locking repair design in the prevention of gap formation using a cadaveric model for linear cyclical loading. Forty flexor digitorum profundus tendons were lacerated and repaired using locked and nonlocked variations of a 4- and 8-strand flexor tendon repair. An incremental cyclical loading protocol from 25 N to 65 N was used. Comparison of the amount of Newton-cycles to reach 1, 2, 3, and 4 mm of gap and the Newton-cycles withstood before failure was performed using 2-way ANOVA. The 8-strand repairs demonstrated significantly increased fatigue strength compared with the 4-strand repairs, but the number of strands crossing the repair site did not significantly affect gap resistance. The locked repairs demonstrated a significant increase in gap resistance to 1 and 2 mm compared with the nonlocked repairs, but the difference was not sustained at higher load cycles. There was no association between gap resistance and fatigue strength. We conclude that an increase in the number of strands significantly increases the fatigue strength of a tendon repair but does not alter its gap resistance to cyclic loading. Locking of the repair does provide additional gap resistance at the relatively low cyclical loads anticipated during the early healing period using an active motion rehabilitation protocol.
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PMID:The role of multiple strands and locking sutures on gap formation of flexor tendon repairs during cyclical loading. 1091 13

Dietary supplementation (SUP) has become a significant part of athletic training. Studies indicate that creatine (Cr) can enhance short-duration, high-intensity activities. This study examined the effect of 21 days of low dose Cr SUP ( approximately 7.7 g/day) and resistance training on force output, power output, duration of mean peak power output, and total work performed until fatigue. A double-blind protocol was used, where an individual, who was not part of any other aspect of the study, randomly assigned subjects to creatine and placebo groups. Forty-one male university athletes were randomly assigned to either Cr (n = 20) or placebo (n = 21) SUP. On the first and last day of the study, subjects were required to perform concentric bench press movements until exhaustion on an isokinetic dynamometer. The dynamometer was hard-wired to a personal computer, which provided force, velocity, and duration measures. Force and power output until fatigue, were used to determine total work, force-time, and power-time relationships. ANOVA results revealed that the Cr subjects performed more total work until fatigue, experienced significantly greater improvements in peak force and peak power, and maintained elevated mean peak power for a longer period of time. These results indicate that Cr SUP can significantly improve factors associated with short-duration, high-intensity activity.
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PMID:The effect of continuous low dose creatine supplementation on force, power, and total work. 1099 50

Before using electromyographic (EMG) variables such as muscle fiber conduction velocity (MFCV) and the mean or median frequency (MDF) of an EMG power spectrum as indicators of muscular fatigue during dynamic exercises, it is necessary to determine the influence of a joint angle, contraction force and contraction speed on the EMG variables. If these factors affect the EMG variables, their influence must be removed or compensated for before discussing fatigue. The vastus lateralis of eight normal healthy male adults was studied. EMG signals during non-fatiguing dynamic knee extension exercises were detected with a three-bar active surface electrode array. EMG variables were calculated from the detected signals and compared with the angle of the knee joint, the extension torque and the extension speed. The extension torque was set at four levels with 10% intervals between 40 and 70% of the maximum voluntary contraction. The extension speed was set at five levels with 60 degrees /s intervals between 0 and 240 degrees /s. Because the joint angle unsystematically affected the MFCV, EMG variables at a given joint angle were extracted for comparison. The influence of the extension torque and speed on the extracted EMG variables was clarified with an ANOVA and a regression analysis. The statistical analyses showed that MFCV increased with the extension torque but did not depend on the extension speed. In contrast, MDF was independent of the extension torque but was dependent on the extension speed. MDF thus showed a behavior different from that of MFCV. It became clear that if MFCV is used as an indicator of muscular fatigue during dynamic exercises, it is at least necessary to extract MFCV at a predetermined joint angle and then remove the influence of extension torque on MFCV.
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PMID:Influence of contraction force and speed on muscle fiber conduction velocity during dynamic voluntary exercise. 1122 22

This study compared the fatigue characteristics of the vastus medialis oblique (VMO), vastus lateralis (VL) and rectus femoris (RF) muscles. Ten healthy subjects with 10 patients with patellofemoral pain syndrome (PFPS) performed an isometric leg press for 60 seconds at 60% MVIC with data collected using surface EMG. The power spectrum was analyzed and the extracted median frequency normalised to calculate a linear regression slope for each muscle. A repeated measures ANOVA revealed no significant differences, neither between the groups (P=0.592) nor the muscles (P=0.434). However, the slopes for the VMO and VL were different between the two groups with similar slopes for the RF. There was much larger variability of MF values in the PFPS group. The VMO:VL ratio calculated from these slopes for the healthy subjects was 1.17 and for the PFPS group was 1.78. These results may indicate unusual features in the fatigue indices of the quadriceps in PFPS.
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PMID:Electromyographic fatigue characteristics of the quadriceps in patellofemoral pain syndrome. 1124 6


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