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Perceived Exertion (perceived + exertion)
Selected AbstractsOn functional motor adaptations: from the quantification of motor strategies to the prevention of musculoskeletal disorders in the neck,shoulder regionACTA PHYSIOLOGICA, Issue 2010P. Madeleine Abstract Background:, Occupations characterized by a static low load and by repetitive actions show a high prevalence of work-related musculoskeletal disorders (WMSD) in the neck,shoulder region. Moreover, muscle fatigue and discomfort are reported to play a relevant initiating role in WMSD. Aims: To investigate relationships between altered sensory information, i.e. localized muscle fatigue, discomfort and pain and their associations to changes in motor control patterns. Materials & Methods:, In total 101 subjects participated. Questionnaires, subjective assessments of perceived exertion and pain intensity as well as surface electromyography (SEMG), mechanomyography (MMG), force and kinematics recordings were performed. Results:, Multi-channel SEMG and MMG revealed that the degree of heterogeneity of the trapezius muscle activation increased with fatigue. Further, the spatial organization of trapezius muscle activity changed in a dynamic manner during sustained contraction with acute experimental pain. A graduation of the motor changes in relation to the pain stage (acute, subchronic and chronic) and work experience were also found. The duration of the work task was shorter in presence of acute and chronic pain. Acute pain resulted in decreased activity of the painful muscle while in subchronic and chronic pain, a more static muscle activation was found. Posture and movement changed in the presence of neck,shoulder pain. Larger and smaller sizes of arm and trunk movement variability were respectively found in acute pain and subchronic/chronic pain. The size and structure of kinematics variability decreased also in the region of discomfort. Motor variability was higher in workers with high experience. Moreover, the pattern of activation of the upper trapezius muscle changed when receiving SEMG/MMG biofeedback during computer work. Discussion:, SEMG and MMG changes underlie functional mechanisms for the maintenance of force during fatiguing contraction and acute pain that may lead to the widespread pain seen in WMSD. A lack of harmonious muscle recruitment/derecruitment may play a role in pain transition. Motor behavior changed in shoulder pain conditions underlining that motor variability may play a role in the WMSD development as corroborated by the changes in kinematics variability seen with discomfort. This prognostic hypothesis was further, supported by the increased motor variability among workers with high experience. Conclusion:, Quantitative assessments of the functional motor adaptations can be a way to benchmark the pain status and help to indentify signs indicating WMSD development. Motor variability is an important characteristic in ergonomic situations. Future studies will investigate the potential benefit of inducing motor variability in occupational settings. [source] Cerebral oxygenation is reduced during hyperthermic exercise in humansACTA PHYSIOLOGICA, Issue 1 2010P. Rasmussen Abstract Aim:, Cerebral mitochondrial oxygen tension (PmitoO2) is elevated during moderate exercise, while it is reduced when exercise becomes strenuous, reflecting an elevated cerebral metabolic rate for oxygen (CMRO2) combined with hyperventilation-induced attenuation of cerebral blood flow (CBF). Heat stress challenges exercise capacity as expressed by increased rating of perceived exertion (RPE). Methods:, This study evaluated the effect of heat stress during exercise on PmitoO2 calculated based on a Kety-Schmidt-determined CBF and the arterial-to-jugular venous oxygen differences in eight males [27 ± 6 years (mean ± SD) and maximal oxygen uptake (VO2max) 63 ± 6 mL kg,1 min,1]. Results:, The CBF, CMRO2 and PmitoO2 remained stable during 1 h of moderate cycling (170 ± 11 W, ,50% of VO2max, RPE 9,12) in normothermia (core temperature of 37.8 ± 0.4 °C). In contrast, when hyperthermia was provoked by dressing the subjects in watertight clothing during exercise (core temperature 39.5 ± 0.2 °C), PmitoO2 declined by 4.8 ± 3.8 mmHg (P < 0.05 compared to normothermia) because CMRO2 increased by 8 ± 7% at the same time as CBF was reduced by 15 ± 13% (P < 0.05). During exercise with heat stress, RPE increased to 19 (19,20; P < 0.05); the RPE correlated inversely with PmitoO2 (r2 = 0.42, P < 0.05). Conclusion:, These data indicate that strenuous exercise in the heat lowers cerebral PmitoO2, and that exercise capacity in this condition may be dependent on maintained cerebral oxygenation. [source] Cerebral oxygenation decreases but does not impair performance during self-paced, strenuous exerciseACTA PHYSIOLOGICA, Issue 4 2010F. Billaut Abstract Aim:, The reduction in cerebral oxygenation (Cox) is associated with the cessation of exercise during constant work rate and incremental tests to exhaustion. Yet in exercises of this nature, ecological validity is limited due to work rate being either fully or partly dictated by the protocol, and it is unknown whether cerebral deoxygenation also occurs during self-paced exercise. Here, we investigated the cerebral haemodynamics during a 5-km running time trial in trained runners. Methods:, Rating of perceived exertion (RPE) and surface electromyogram (EMG) of lower limb muscles were recorded every 0.5 km. Changes in Cox (prefrontal lobe) were monitored via near-infrared spectroscopy through concentration changes in oxy- and deoxyhaemoglobin (,[O2Hb], ,[HHb]). Changes in total Hb were calculated (,[THb] = ,[O2Hb] + ,[HHb]) and used as an index of change in regional blood volume. Results:, During the trial, RPE increased from 6.6 ± 0.6 to 19.1 ± 0.7 indicating maximal exertion. Cox rose from baseline to 2.5 km (,,[O2Hb], ,,[HHb], ,,[THb]), remained constant between 2.5 and 4.5 km, and fell from 4.5 to 5 km (,,[O2Hb], ,,[HHb], ,,[THb]). Interestingly, the drop in Cox at the end of the trial coincided with a final end spurt in treadmill speed and concomitant increase in skeletal muscle recruitment (as revealed by higher lower limb EMG). Conclusion:, Results confirm the large tolerance for change in Cox during exercise at sea level, yet further indicate that, in conditions of self-selected work rate, cerebral deoxygenation remains within a range that does not hinder strenuous exercise performance. [source] Association between fatigue and failure to preserve cerebral energy turnover during prolonged exerciseACTA PHYSIOLOGICA, Issue 1 2003L. Nybo Abstract Aim: This study evaluated if the fatigue and apathy arising during exercise with hypoglycaemia could relate to a lowering of the cerebral metabolic rates of glucose and oxygen. Methods and results: Six males completed 3 h of cycling with or without glucose supplementation in random order. Cerebral blood flow, metabolism and interleukin-6 (IL-6) release were evaluated with the Kety,Schmidt technique. Blood glucose was maintained during the glucose trial, while it decreased from 5.2 ± 0.1 to 2.9 ± 0.3 mmol L,1 (mean ± SE) after 180 min of exercise in the placebo trial with a concomitant increase in perceived exertion (P < 0.05). During hypoglycaemia, the cerebral glucose uptake was reduced from 0.34 ± 0.05 to 0.28 ± 0.04 ,mol g,1 min,1, while the cerebral uptake of , -hydroxybutyrate increased to 5 ± 1 pmol g,1 min,1 (P < 0.05). The reduced glucose uptake was accompanied by a lowering of the cerebral metabolic rate of oxygen from 1.84 ± 0.19 mmol g,1 min,1 during exercise with glucose supplementation to 1.60 ± 0.16 mmol g,1 min,1 during hypoglycaemia (P < 0.05). In addition, the cerebral IL-6 release was reduced from 0.4 ± 0.1 to 0.0 ± 0.1 pg g,1 min,1 (P < 0.05). Conclusions: Exercise-induced hypoglycaemia limits the cerebral uptake of glucose, exacerbates exercise, reduces the cerebral metabolic rate of oxygen and attenuates the release of IL-6 from the brain. [source] Cerebral Metabolism is Influenced by Muscle Ischaemia During Exercise in HumansEXPERIMENTAL PHYSIOLOGY, Issue 2 2003Mads K. Dalsgaard Maximal exercise reduces the cerebral metabolic ratio (O2/(glucose + 1/2lactate)) to < 4 from a resting value close to 6, and only part of this decrease is explained by the ,intent' to exercise. This study evaluated whether sensory stimulation of brain by muscle ischaemia would reduce the cerebral metabolic ratio. In 10 healthy human subjects the cerebral arterial-venous differences (a-v differences) for O2, glucose and lactate were assessed before, during and after three bouts of 10 min cycling with equal workload: (1) control exercise at light intensity, (2) exercise that elicited a high rating of perceived exertion due to a 100 mmHg thigh cuff, and (3) exercise followed by 5 min of post-exercise muscle ischaemia that increased blood pressure by , 20%. Control exercise did not significantly affect the a-v differences. However, during the recovery from exercise with thigh cuffs the cerebral metabolic ratio decreased from a resting value of 5.4 ± 0.2 to 4.0 ± 0.4 (mean ±s.e.m.. P < 0.05) as a discrete lactate efflux from the brain at rest shifted to a slight uptake. Also, following post-exercise muscle ischaemia, the cerebral metabolic ratio decreased to 4.5 ± 0.3 (P < 0.05). The results support the hypothesis that during exercise, cerebral metabolism is influenced both by the mental effort to exercise and by sensory input from skeletal muscles. [source] Identification of the maximum acceptable frequencies of upper-extremity motions in the sagittal planeHUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 3 2009Ochae Kwon The present study examined the maximum acceptable frequencies (MAFs; motions/min) of upper-extremity motions in the sagittal plane at different forces. A dumbbell of 9.8 or 39.2 N was rotated by the arm about the shoulder, the forearm about the elbow, and the hand about the wrist; a dynamometer was pressed to 2.45 or 9.8 N by the index finger. Seventeen right-handed Korean men in their 20s without any history of musculoskeletal disorders received 1 hour of individual training and conducted each upper-extremity task for 30 minutes a day, assuming they were on an incentive basis. The participants determined their MAFs for 8 hours of work by the self-adjustment method, and work pulse (change in heart rate; beats per minute [bpm]) and rating of perceived exertion (RPE) were measured. For a limited set of conditions, the reproducibility of the MAF experimental protocol was found satisfactory (r = 0.97; interclass correlation coefficient > 0.95). The average MAFs of arm, forearm, hand, and index finger motions were 24, 45, 56, and 128 at their low force level and 9, 20, 30, and 66 at their high force level. The average work pulses of arm, forearm, and hand motions were 3.0, 2.1, and 1.5 times that of index finger motion (4.2 bpm at their low force level and 5.7 bpm at their high force level). The maximum average RPEs at the upper-extremity regions ranged from 2.1 (weak) to 3.1 (moderate) in Borg's CR-10 scale. © 2009 Wiley Periodicals, Inc. [source] Efficacy and Feasibility of a Novel Tri-Modal Robust Exercise Prescription in a Retirement Community: A Randomized, Controlled TrialJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 1 2007Michael K. Baker BAppSc OBJECTIVES: To test the feasibility and efficacy of current guidelines for multimodal exercise programs in older adults. DESIGN: Randomized, controlled trial. SETTING: Retirement village. PARTICIPANTS: Thirty-eight subjects (14 men and 24 women) aged 76.6 ± 6.1. INTERVENTION: A wait list control or 10 weeks of supervised exercise consisting of high-intensity (80% of one-repetition maximum (1RM)) progressive resistance training (PRT) 3 days per week, moderate-intensity (rating of perceived exertion 11 to 14/20) aerobic training 2 days per week, and progressive balance training 1 day per week. MEASUREMENTS: Blinded assessments of dynamic muscle strength (1RM), balance, 6-minute walk, gait velocity, chair stand, stair climb, depressive symptoms, self-efficacy, and habitual physical activity level. RESULTS: Higher baseline strength and psychological well-being were associated with better functional performance. Strength gains over 10 weeks averaged 39±31% in exercise, versus 21±24% in controls (P=.10), with greater improvements in hip flexion (P=.01), hip abduction (P=.02), and chest press (P=.04) in the exercise group. Strength adaptations were greatest in exercises in which the intended continuous progressive overload was achieved. Stair climb power (12.3±15%, P=.002) and chair stand time (,7.1±15%, P=.006) improved significantly and similarly in both groups. Reduction in depressive symptoms was significantly related to compliance (attendance rate r=,0.568, P=.009, PRT progression in loading r=,0.587, P=.02, and total volume of aerobic training r=,0.541, P=.01), as well as improvements in muscle strength (r=,0.498, P=.002). CONCLUSION: Robust physical and psychological adaptations to exercise are linked, although volumes and intensities of multiple exercise modalities sufficient to cause significant adaptation appear difficult to prescribe and adhere to simultaneously in older adults. [source] Physiological and performance effects of glycerol hyperhydration and rehydrationNUTRITION REVIEWS, Issue 12 2009Simon P Van Rosendal Studies have shown that beverages containing glycerol can enhance and maintain hydration status and may improve endurance exercise performance by attenuating adverse physiological changes associated with dehydration. Improvements to performance include increased endurance time to exhaustion by up to 24%, or a 5% increase in power or work. However, some studies have found no performance benefits during either prolonged exercise or specific skill and agility tests. In studies that have shown benefits, the improvements have been associated with thermoregulatory and cardiovascular changes. These include increased plasma volume and sweat rates, as well as reduced core temperature and ratings of perceived exertion. In a very small number of subjects, glycerol consumption has been associated with side-effects including nausea, gastrointestinal discomfort, dizziness, and headaches. In summary, while glycerol and fluid ingestion results in hyperhydration, the documented benefits to exercise performance remain inconsistent. [source] The Effects of Rate-Adaptive Atrial Pacing Versus Ventricular Backup Pacing on Exercise Capacity in Patients with Left Ventricular DysfunctionPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1 2009M.S.C.E., ROD PASSMAN M.D. Background: Atrial rate-adaptive pacing may improve cardiopulmonary reserve in patients with left ventricular dysfunction. Methods: A randomized, blinded, single-crossover design enrolled dual-chamber implantable defibrillator recipients without pacing indications and an ejection fraction ,40% to undergo cardiopulmonary exercise treadmill stress testing in both atrial rate-adaptive pacing (AAIR) and ventricular demand pacing (VVI) pacing modes. The primary endpoint was change in peak oxygen consumption (VO2). Secondary endpoints were changes in anaerobic threshold, perceived exertion, exercise duration, and peak blood pressure. Results: Ten patients, nine males, eight with New York Heart Association class I, mean ejection fraction 24 ± 7%, were analyzed. Baseline VO2 was 3.6 ± 0.5 mL/kg/min. Heart rate at peak exercise was significantly higher during AAIR versus VVI pacing (142 ± 18 vs 130 ± 23 bpm; P = 0.05). However, there was no difference in peak VO2 (AAIR 23.7 ± 6.1 vs VVI 23.8 ± 6.3 mL/kg/min; P = 0.8), anaerobic threshold (AAIR 1.3 ± 0.3 vs VVI 1.2 ± 0.2 L/min; P = 0.11), rate of perceived exertion (AAIR 7.3 ± 1.5 vs VVI 7.8 ± 1.2; P = 0.46), exercise duration (AAIR 15 minutes, 46 seconds ± 2 minutes, 54 seconds vs VVI 16 minutes, 3 seconds ± 2 minutes, 48 seconds; P = 0.38), or peak systolic blood pressure (AAIR 155 ± 22 vs VVI 153 ± 21; P = 0.61) between the two pacing modes. Conclusion: In this study, AAIR pacing did not improve peak VO2, anaerobic threshold, rate of perceived exertion, or exercise duration compared to VVI backup pacing in patients with left ventricular dysfunction and no pacing indications. [source] Influence of successive bouts of fatiguing exercise on perceptual and physiological markers during an incremental exercise testPSYCHOPHYSIOLOGY, Issue 1 2009Jeremy B.J. Coquart Abstract The purpose of this study was to examine the effects of a succession of fatiguing stages, on ratings of perceived exertion (RPE) and estimated time limits (ETL) during an incremental exercise test. Twenty-seven cyclists performed a continuous incremental test and a discontinuous test with randomized workloads. A linear mixed model was used to compare the RPE, ETL, respiratory gas, heart rate, and blood data obtained during the two exercise tests. RPE and ETL were not significantly different between the tests. Ventilation, breathing frequency, heart rate, and blood lactate concentration were significantly higher during the last incremental test workloads. In conclusion, although the incremental exercise test generated higher cardiorespiratory and muscular workloads than observed during the randomized exercise test, most likely due to a greater fatiguing process, these higher workloads did not influence the perceptual response. [source] The effect of antecedent fatiguing activity on the relationship between perceived exertion and physiological activity during a constant load exercise taskPSYCHOPHYSIOLOGY, Issue 5 2007Roger Eston Abstract This study assessed the relationship between the rate of change of the rating of perceived exertion (RPE), physiological activity, and time to volitional exhaustion. After completing a graded exercise test, 10 participants cycled at a constant load equating to 75% of peak oxygen uptake (V, O2peak) to exhaustion. Participants performed two further constant load exercise tests at 75%V, O2peak in a fresh state condition within the next 7 days. The RPE was regressed against time and percentage of the time (%time) to volitional exhaustion in both conditions. Despite a lower respiratory exchange ratio (RER) and higher heart rate at the start of the exercise bout in the fatigued condition, there were no differences in RPE at the onset or completion of exercise. As expected, the rate of increase in RPE was greater in the fatigued condition, but there were no differences when expressed against %time. Results suggest that RPE is set at the start of exercise using a scalar internal timing mechanism, which regulates RPE by altering the gain of the relationship with physiological parameters such as heart rate and RER when these are altered by previous fatiguing exercise. [source] Physical training and testing in patients with chronic obstructive pulmonary diseaseTHE CLINICAL RESPIRATORY JOURNAL, Issue 1 2007Ragnheišur Harpa Arnardóttir Abstract Introduction:, The effects of different training modes need to be investigated further in patients with chronic obstructive pulmonary disease (COPD). Both advanced laboratory tests and field tests are used in patients with COPD to evaluate effects of interventions such as pulmonary rehabilitation. Aims:, The overall aims of the studies were to investigate the effects of different training modalities on exercise capacity and on health-related quality of life (HRQoL) in patients with moderate or severe COPD and, further, to explore two of the physical field tests used in pulmonary rehabilitation, the 12-min walk test and the incremental shuttle walking test (ISWT). Materials and Methods:, Patients with moderate or severe COPD were included. In study I (n = 57), the 12-min walk test was performed three times within 1 week. Exercise-induced hypoxemia (EIH) was assessed by pulse oximeter and was defined as SpO2 < 90%. In study II (n = 93), performance on ISWT was compared to performance on two different cycle tests. In study III (n = 42), the effects of two different combination training programmes were compared when training twice a week for 8 weeks. One programme was mainly based on endurance training (group A), and the other was based on resistance training and on callisthenics (group B). In study IV (n = 60), endurance training with interval resistance was compared to endurance training with continuous resistance. Results:, In study I, the 12-min walking distance (12MWD) did not increase on retesting in patients with EIH, but increased significantly on retesting in the non-EIH patients. In study II, the ISWT was as good a predictor of peak exercise capacity (W peak) as peak oxygen uptake (VO2 peak) was. In study III, W peak and 12MWD increased in group A but not in group B. HRQoL, anxiety and depression were unchanged in both groups. Ratings of perceived exertion at rest were significantly lower in group A than in group B after training and during 12 months of follow-up. Twelve months post training, 12MWD was back to baseline in group A, but was significantly shorter than at baseline in group B. Patients with moderate and severe COPD responded to training in the same way. In study IV, both interval and continuous endurance training increased W peak, VO2 peak, peak exhaled carbon dioxide (VCO2 peak) and 12MWD. Likewise, HRQoL, dyspnoea during activities of daily life, anxiety and depression improved similarly in both groups. At a fixed, sub-maximal workload (isotime), the interval training reduced oxygen cost and ventilatory demand significantly more than the continuous training did. Conclusions:, EIH affects the retest effects on 12MWD. W peak can be predicted from an ISWT similarly well as from VO2 peak. A short training programme can improve W peak and 12MWD when based mainly on endurance training. Both patients with moderate and severe COPD respond to training in the same way. A short endurance training intervention can possibly delay decline in 12MWD for 1 year. Both interval and continuous endurance training improves physical performance and HRQoL. Interval training lowers the energy cost of sub-maximal work more than continuous training does. [source] Ventilation threshold as a measure of impaired physical performance in adults with growth hormone excessCLINICAL ENDOCRINOLOGY, Issue 3 2002Scott G. Thomas Summary objective Fatigue is a prominent symptom among patients with GH excess and acromegaly. Identifying the physiological basis of such complaints and obtaining objective measures to quantify their severity remains an ongoing challenge. We investigated whether submaximal measures of aerobic performance can be used to assess GH excess-associated fatigue objectively. design and patients To investigate this possibility we examined the relation between physical function and physical capacity in 12 patients with active acromegaly and persistent fatigue before and after 3 and 6 months of treatment with the long-acting somatostatin analogue octreotide (LAR®). measurements Heart rate (HR) and rating of perceived exertion (RPE using Borg's 10-point scale) were measured during a 160-metre self-paced walk test (SPW). Maximum oxygen uptake (VO2max) and ventilation threshold (VeT: a measure of work rate when breathlessness develops) were measured during a progressive treadmill test to fatigue or symptom-limited maximum. The Profile Of Mood States questionnaire (POMS) was used to quantify subjective feelings of fatigue and vigour. Morning fasting levels of GH and IGF-I were measured using immunoassay of serum samples. results SPW speed at a fast pace of 1·69 ± 0·18 m/s was achieved with higher than normal HR (112 ± 15/min; normal = 102) and RPE (2·4 ± 1·2). Similar to GH-deficient adults, VO2max (22·6 ± 6·4 ml.kg,1.min,1; normal ~30 ml.kg,1.min,1) and VeT (13·1 ± 2·9 ml.kg,1.min,1; predicted normal ~16 ml.kg,1(min,1) were low. However, VeT occurred at a normal fraction of VO2max (VeT/VO2max = 0·58). VeT was significantly increased and plasma IGF-I levels reduced following 3 and 6 months of octreotide LAR® treatment. Reduction in circulating IGF-I levels was correlated with improvement in reported vigour (r = 0·85) and VeT (r = 0·65) (P < 0·05). conclusions Our findings demonstrate impairment in physical function and physical capacity consistent with the perception of increased fatigue among acromegalic patients. These objective measures of compromised physical function are similar to the changes that we have reported previously in adults with GH deficiency. Taken together, these data suggest that a narrow window for GH/IGF-I levels is required to maintain optimal physical function. [source] Intensity of Nordic Walking in young females with different peak O2 consumptionCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 5 2009Toivo Jürimäe Summary The purpose of this cross - sectional study was to determine the physiological reaction to the different intensity Nordic Walking exercise in young females with different aerobic capacity values. Twenty-eight 19,24-year-old female university students participated in the study. Their peak O2 consumption (VO2 peak kg,1) and individual ventilatory threshold (IVT) were measured using a continuous incremental protocol until volitional exhaustion on treadmill. The subjects were analysed as a whole group (n = 28) and were also divided into three groups based on the measured VO2 peak kg,1 (Difference between groups is 1 SD) as follows: 1. >46 ml min,1 kg,1 (n = 8), 2. 41,46 ml min,1 kg,1 (n = 12) and 3. <41 ml min,1 kg,1 (n = 8). The second test consisted of four times 1 km Nordic Walking with increasing speed on the 200 m indoor track, performed as a continuous study (Step 1 , slow walking, Step 2 , usual speed walking, Step 3 , faster speed walking and Step 4 , maximal speed walking). During the walking test expired gas was sampled breath-by-breath and heart rate (HR) was recorded continuously. Ratings of perceived exertion (RPE) were asked using the Borg RPE scale separately for every 1 km of the walking test. No significant differences emerged between groups in HR of IVT (172·4 ± 10·3,176·4 ± 4·9 beats min,1) or maximal HR (190·1 ± 7·3,191·6 ± 7·8 beats min,1) during the treadmill test. During maximal speed walking the speed (7·4 ± 0·4,7·5 ± 0·6 km h,1) and O2 consumption (30·4 ± 3·9,34·0 ± 4·5 ml min,1 kg,1) were relatively similar between groups (P > 0·05). However, during maximal speed walking, the O2 consumption in the second and third groups was similar with the IVT (94·9 ± 17·5% and 99·4 ± 15·5%, respectively) but in the first group it was only 75·5 ± 8·0% from IVT. Mean HR during the maximal speed walking was in the first group 151·6 ± 12·5 beats min,1, in the second (169·7 ± 10·3 beats min,1) and the third (173·1 ± 15·8 beats min,1) groups it was comparable with the calculated IVT level. The Borg RPE was very low in every group (11·9 ± 2·0,14·4 ± 2·3) and the relationship with VO2and HR was not significant during maximal speed Nordic Walking. In summary, the present study indicated that walking is an acceptable exercise for young females independent of their initial VO2 peak level. However, females with low initial VO2 peak can be recommended to exercise with the subjective ,faster speed walking'. In contrast, females with high initial VO2 peak should exercise with maximal speed. [source] Prefrontal cortex oxygenation during incremental exercise in chronic fatigue syndromeCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 6 2008J. Patrick Neary Summary This study examined the effects of maximal incremental exercise on cerebral oxygenation in chronic fatigue syndrome (CFS) subjects. Furthermore, we tested the hypothesis that CFS subjects have a reduced oxygen delivery to the brain during exercise. Six female CFS and eight control (CON) subjects (similar in height, weight, body mass index and physical activity level) performed an incremental cycle ergometer test to exhaustion, while changes in cerebral oxy-haemoglobin (HbO2), deoxy-haemoglobin (HHb), total blood volume (tHb = HbO2 + HHb) and O2 saturation [tissue oxygenation index (TOI), %)] was monitored in the left prefrontal lobe using a near-infrared spectrophotometer. Heart rate (HR) and rating of perceived exertion (RPE) were recorded at each workload throughout the test. Predicted VO2peak in CFS (1331 ± 377 ml) subjects was significantly (P , 0·05) lower than the CON group (1990 ± 332 ml), and CFS subjects achieved volitional exhaustion significantly faster (CFS: 351 ± 224 s; CON: 715 ± 176 s) at a lower power output (CFS: 100 ± 39 W; CON: 163 ± 34 W). CFS subjects also exhibited a significantly lower maximum HR (CFS: 154 ± 13 bpm; CON: 186 ± 11 bpm) and consistently reported a higher RPE at the same absolute workload when compared with CON subjects. Prefrontal cortex HbO2, HHb and tHb were significantly lower at maximal exercise in CFS versus CON, as was TOI during exercise and recovery. The CFS subjects exhibited significant exercise intolerance and reduced prefrontal oxygenation and tHb response when compared with CON subjects. These data suggest that the altered cerebral oxygenation and blood volume may contribute to the reduced exercise load in CFS, and supports the contention that CFS, in part, is mediated centrally. [source] | |||||||||||||