Category-ratio Scale Research Articles

The effect of eccentric arm cycling on muscle damage and injury-related biomarkers.

There is a scarcity of information regarding the effect of upper-body eccentric exercise on biomarkers of muscle damage. This study sought to investigate the effect of eccentric arm cycling on muscle damage [exercise-induced muscle damage (EIMD)]. Ten subjects performed a 15 min eccentric arm cycling protocol (cadence 49 ± 7 rpm, power absorbed 248 ± 34 W). Maximal voluntary contraction (MVC) of the elbow flexors was evaluated at rest and at 5 min, 24 h, and 48 h post-exercise. In addition, blood samples were drawn at rest and thereafter at 30 min, 24 h, and 48 h intervals after exercise for quantification of creatine kinase (CK), myoglobin, lactate dehydrogenase (LDH) and endothelin (ET-1) concentrations. Delayed onset muscle soreness (DOMS) was assessed using a category ratio scale (0-10). Myoglobin was increased from baseline at 30 min post-exercise (+114%, 46.08 ± 22.17 µg/L, p = 0.018). Individual peak values were higher than baseline values for CK (+72.8%, 204 ± 138 U/L, p = 0.046) and LDH (+17%, 3.3 ± 0.88 nmole/min/mL, p = 0.017), but not for ET-1 (+9%, 1.4 ± 0.48 pg/mL, p = 0.45). DOMS was reported at 24 h (median 4) and 48 h (median 4) post-exercise and MVC of the elbow flexors were reduced from baseline (216 ± 44 N) at 5 min (-34%, 147 ± 61 N, p < 0.001), 24 h (-17%, 181 ± 56 N, p = 0.005) and 48 h (-9%, 191 ± 54 N, p = 0.003). Eccentric arm cycling incites EIMD with reduced MVC and elevation of myoglobin, CK and LDH.

Borg's exertion scale did not coincide with ventilatory anaerobic threshold in atrial fibrillation patients with restored sinus rhythm after ablation.

The determination of precise exercise intensity is essential for effective exercise rehabilitation. The Borg rating of perceived exertion category ratio (CR) scale is utilized to prescribe an appropriate level of exertion intensity. A Borg CR of approximately 13 coincides with the ventilatory aerobic threshold (VAT). Patients with atrial fibrillation (AF) exhibit various symptoms. We hypothesized that the workload at Borg CR13 (Borg CR13-Watt) differs from the workload at the VAT level (VAT-Watt) in AF patients with restored sinus rhythm (SR) following ablation. Accordingly, the relationship between Borg CR13-Watt and VAT-Watt was studied in patients with restored SR. Cardiopulmonary exercise testing (CPET) was performed at 101±88 days after ablation in 150 patients using a bicycle ergometer. No adverse events were observed during CPET. Borg CR13-Watt was significantly higher than VAT-Watt (67.2±27.8 Watt vs. 54.7±17.6 Watt, P<0.0001). Borg CR13-Watt showed significant linear regression with VAT-Watt (regression coefficient, 0.49, P<0.01; correlation coefficient, 0.80, P<0.01). Higher Borg CR13-Watt was associated with greater differences between Borg CR13-Watt and VAT-Watt (ΔWatt). The Bland-Altman plot showed nonconcordance between the two. Male sex, use of antiarrhythmic drugs, and smoking had contributed to the increased ΔWatt. Duration from ablation to time of CPET did not correlate with ΔWatt. Therefore, Borg CR13-Watt did not coincide with VAT-Watt in patients with restored SR. Higher Borg CR13-Watt was associated with greater ΔWatt. Prescribing exertion intensity as determined solely by perceived exertion is inadequate. CPET is required to determine the precise exercise intensity in AF patients with restored SR after ablation.

Reference values for leg effort during incremental cycle ergometry in non-trained healthy men and women, aged 19-85.

Heightened sensation of leg effort contributes importantly to poor exercise tolerance in patient populations. We aim to provide a sex- and age-adjusted frame of reference to judge symptom's normalcy across progressively higher exercise intensities during incremental exercise. Two-hundred and seventy-five non-trained subjects (130 men) aged 19-85 prospectively underwent incremental cycle ergometry. After establishing centiles-based norms for Borg leg effort scores (0-10 category-ratio scale) versus work rate, exponential loss function identified the centile that best quantified the symptom's severity individually. Peak O2 uptake and work rate (% predicted) were used to threshold gradually higher symptom intensity categories. Leg effort-work rate increased as a function of age; women typically reported higher scores at a given age, particularly in the younger groups (p < 0.05). For instance, "heavy" (5) scores at the 95th centile were reported at ~200 W (<40 years) and ~90 W (≥70 years) in men versus ~130 W and ~70 W in women, respectively. The following categories of leg effort severity were associated with progressively lower exercise capacity: ≤50th ("mild"), >50th to <75th ("moderate"), ≥75th to <95th ("severe"), and ≥ 95th ("very severe") (p < 0.05). Although most subjects reporting peak scores <5 were in "mild" range, higher scores were not predictive of the other categories (p > 0.05). This novel frame of reference for 0-10 Borg leg effort, which considers its cumulative burden across increasingly higher exercise intensities, might prove valuable to judging symptom's normalcy, quantifying its severity, and assessing the effects of interventions in clinical populations.

Effects of Multicomponent Exercise on Community-Dwelling Older Adults With Mild Cognitive Impairment.

To explore the effects of a group-based multicomponent exercise program on general cognitive functioning, depression, and social functioning in community-dwelling older adults with mild cognitive impairment (MCI) and whether the effects can be maintained. Fifty older adults with MCI were conveniently recruited from two communities in the study area and randomly assigned to the intervention group or control group. The intervention group received three sessions of 60-minute, multicomponent exercise per week for 3 months, plus MCI-related health education. The control group only received MCI-related health education. Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment Beijing Version (MoCA-BJ) were used to assess general cognitive function. The Functional Activities Questionnaire (FAQ) and Geriatric Depression Scale (GDS-30) were used to evaluate participants' social function and depression, respectively. Participants' exercise intensity was assessed using the Category Ratio Scale. After the 3-month intervention, there were significant improvements in general cognitive function (p = 0.046), attention (p = 0.009), delayed recall (p = 0.015), and social function (p = 0.011) in the intervention group compared with the control group. However, after 3-month postintervention follow up, no significant differences in MMSE, MoCA-BJ, GDS-30, and FAQ scores were noted between groups. The 3-month multicomponent exercise program improved general cognitive function and social functioning in community-dwelling older adults with MCI. However, there was no evidence that these benefits lasted for another 3 months after stopping the exercise program. [Research in Gerontological Nursing, 17(2), 65-79.].

Abnormal Exertional Breathlessness on Cardiopulmonary Cycle Exercise Testing in Relation to Self-Reported and Physiologic Responses in Chronic Airflow Limitation

Exertional breathlessness is a cardinal symptom of cardiorespiratory disease. How does breathlessness abnormality, graded using normative reference equations during cardiopulmonary exercise testing (CPET), relate to self-reported and physiological responses in people with chronic airflow limitation (CAL)? An analysis was done of people aged≥ 40 years with CAL undergoing CPET in the Canadian Cohort Obstructive Lung Disease study. Breathlessness intensity ratings (Borg CR10 scale [0-10 category-ratio scale for breathlessness intensity rating]) were evaluated in relation to power output (W), rate of oxygen uptake (V˙o2), and minute ventilation (V˙e) at peak exercise, using normative reference equations as follows: (1) probability of breathlessness normality (probability of having an equal or greater Borg CR10 rating among healthy; lower probability reflecting more severe breathlessness) and (2) presence of abnormal breathlessness (rating above the upper limit of normal). Associations with relevant participant-reported and physiologic outcomes were evaluated. We included 330 participants (44%women): mean ± SD age, 64 ± 10 years (range, 40-89 years); FEV1/FVC, 57.3%± 8.2%; FEV1, 75.6%± 17.9%predicted. Abnormally low exercise capacity (peak V˙o2< lower limit of normal) was present in 26%. Relative to peak W, V˙o2, and V˙e, abnormally high breathlessness was present in 26%, 25%, and 18%of participants. For all equations, abnormally high exertional breathlessness was associated with worse lung function, exercise capacity, self-reported symptom burden, physical activity, and health-related quality of life; and greater physiological abnormalities during CPET. Abnormal breathlessness graded using CPET normative reference equations was associated with worse clinical, physiological, and functional outcomes in people with CAL, supporting construct validity of abnormal exertional breathlessness.

Acute Effects of a Combat Sport Environment on Self-Control and Pain Perception Inhibition: A Preliminary Study in a New Ecological Framework

Intense sports activities affect cognitive, perceptual, and physiological domains, possibly concurring in reducing pain perception and anxiety. Within a framework for a new socio-ecological narrative that considers opposition (such as fighting) and collaboration (cooperative learning) as carriers of self-control and pain perception inhibition, we investigated the acute effects of a judo-specific session on cognitive (inhibitory control and simple reaction time), perceptual (pain and fatigue), affective (anxiety) and physiological (hormone profile) domains. Eleven male black belt judokas (age 39.0 ± 13.9 years; training experience: 23.2 ± 14.4 years) were recruited and tested before and after judo randori and resting sessions. Inhibitory control and simple reaction time were assessed via the Flanker task and clinical reaction time test, pain and fatigue were assessed using Borg’s category-ratio scale (CR-10), and the state–trait anxiety inventory Y-1 test assessed anxiety. Glucose, insulin, cortisol, creatinine, and irisin levels were measured. Cognitive performance, perception of fatigue and physiological variables increased after randori bouts, while pain decreased. Inhibitory control, perception of pain, perception of fatigue and glucose, cortisol, and creatinine significantly differed (p &lt; 0.05) between randori and resting sessions. A high-intensity randori may induce acute beneficial effects on cognitive, perceptual, and physiological domains. Further studies should compare the results with the outcomes from a collaborative and non-agonist environment and confirm the socio-ecologic framework.

Increased Metabolic Demand During Outside Walking in Darkness With No Vision or With Visual Aid.

For tactical reasons, the foot-borne soldiers sometimes undertake nighttime operations. However, the metabolic demand during walking in complete darkness may be markedly increased. The purpose of this study was to investigate if metabolic demand and kinematics would change while walking on a gravel road and a slightly hilly trail in darkness with or without visual aid. Fourteen cadets (11 men and 3 women, age: 25 ± 7 years, height: 178 ± 8 cm, and weight: 78 ± 13 kg) walked at 4 km/h on a straight gravel road and on a slightly hilly forest trail (n = 9). Both trials were performed at nighttime under four different conditions, wearing a headlamp (Light), blindfold (Dark), monocular (Mono), or binocular (Bino) night vision goggles. During the 10-minute walks, oxygen uptake, heart rate, and kinematic data were assessed. Ratings of perceived exertion, discomfort, and mental stress were evaluated after each condition using a category ratio scale. Physiologic and kinematic variables were evaluated using repeated-measures analysis of variance, whereas ratings were evaluated using non-parametric Friedman analysis of variance. Oxygen uptake was higher in all three conditions with no or limited vision (Dark, Mono, and Bino) than in the Light condition (P ≤ 0.02) when walking on both the gravel road (+5-8%) and the forest trail (+6-14%). Heart rate was higher during the Dark than during the Light condition when walking on the forest trail, whereas there was no difference between conditions on the gravel road. During both trials, gait frequency was higher during the Dark than during the Light, Mono, and Bino conditions. Ratings were generally low during all conditions. Walking on a gravel road or a forest trail wearing a blindfold or visual aid increased the metabolic demand. Thus, it appears that the metabolic demand is higher during overground walking with night vision goggles than with full vision, which may influence the performance of nighttime operations.

Validity and Reliability of Facial Rating of Perceived Exertion Scales for Training Load Monitoring.

van der Zwaard, S, Hooft Graafland, F, van Middelkoop, C, and Lintmeijer, LL. Validity and reliability of facial rating of perceived exertion scales for training load monitoring. J Strength Cond Res 37(5): e317-e324, 2023-Rating of perceived exertion (RPE) is often used by coaches and athletes to indicate exercise intensity, which facilitates training load monitoring and prescription. Although RPE is typically measured using the Borg's category-ratio 10-point scale (CR10), digital sports platforms have recently started to incorporate facial RPE scales, which potentially have a better user experience. The aim of this study was to evaluate the validity and reliability of a 5-point facial RPE scale (FCR5) and a 10-point facial RPE scale (FCR10), using the CR10 as a golden standard and to assess their use for training load monitoring. Forty-nine subjects were grouped into 17 untrained (UT), 19 recreationally trained (RT), and 13 trained (T) individuals Subjects completed 9 randomly ordered home-based workout sessions (3 intensities × 3 RPE scales) on the Fitchannel.com platform. Heart rate was monitored throughout the workouts. Subjects performed 3 additional workouts to assess reliability. Validity and reliability of both facial RPE scales were low in UT subjects (intraclass correlation [ICC] ≤ 0.44, p ≤ 0.06 and ICC ≤ 0.43, p ≥ 0.09). In RT and T subjects, validity was moderate for FCR5 (ICC ≥ 0.72, p < 0.001) and good for FCR10 (ICC ≥ 0.80, p < 0.001). Reliability for these groups was rather poor for FCR5 (ICC = 0.51, p = 0.006) and moderate for FCR10 (ICC = 0.74, p < 0.001), but it was excellent for CR10 (ICC = 0.92, p < 0.001). In RT and T subjects, session RPE scores were also strongly related to Edward's training impulse scores ( r ≥ 0.70, p < 0.001). User experience was best supported by the FCR10 scale. In conclusion, researchers, coaches, strength and conditioning professionals, and digital sports platforms are encouraged to incorporate the valid and reliable FCR10 and not FCR5 to assess perceived exertion and internal training load of recreationally trained and trained individuals.

Evidence That Rating of Perceived Exertion Growth During Fatiguing Tasks is Scalar and Independent of Exercise Mode.

The relationship between the percentage of a fatiguing ambulatory task completed and rating of perceived exertion (RPE) appears to be linear and scalar, with a relatively narrow "window." Recent evidence has suggested that a similar relationship may exist for muscularly demanding tasks. To determine whether muscularly demanding tasks fit within this "ambulatory window," we tested resistance-trained athletes performing bench press and leg press with different loadings predicted to allow 5, 10, 20, and 30 repetitions and measured RPE (category ratio scale) at the end of the concentric action for each repetition. There was a regular, and strongly linear, pattern of growth of RPE for both bench press (r = .89) and leg press (r = .90) during the tasks that allowed 5.2 (1.2), 11.6 (1.9), 22.7 (2.0), and 30.8 (3.2) repetitions for bench press and 5.5 (1.5), 11.4 (1.6), 20.2 (3.0), and 32.4 (4.2) repetitions for leg press, respectively. The path of the RPE growth versus percentage task fit within the window evident for ambulatory tasks. The results suggest that the RPE versus percentage task completed relationship is scalar, relatively linear, and apparently independent of exercise mode.

Job requirements and physical demands (JRPD) questionnaire: cross-cultural adaptation and psychometric evaluation in Iranian Army personnel with chronic low back pain

BackgroundBiomechanical risk factors have been identified as the main predisposing factor of chronic low back pain (CLBP), especially in Army personnel. The Job Requirements and Physical Demands (JRPD) questionnaire has been developed to assess the biomechanical exposures related to CLBP. Examining the biomechanical risk factors could prevent CLBP. This study aimed to translate and cross-culturally adapt the JRPD into Persian and assess its psychometric properties among Iranian male Army personnel with CLBP.MethodsIn this cross-sectional study, the content validation of the JRPD was assessed after translating to Persian. The Persian JRPD was administered to 198 male Army personnel with CLBP, with an interval of 7 days, to assess test-retest reliability, including Cronbach’s α, intraclass correlation coefficients (ICC), standard error of measurement (SEM), and minimal detectable change at 95% confidence interval (MDC95%). Scores of the Persian JRPD were correlated with the scores of visual analog scale (VAS), Borg’s category-ratio (CR10) scale, general health questionnaire-28 (GHQ-28), and physical functioning (PF1 and PF2) subscale of the 12-item short-form health survey (SF-12) to assess convergent validity using Spearman correlation for a priori hypotheses.ResultsThe Persian JRPD had good content validity evidenced by the higher content validity index (> 0.70). The questionnaire had a significant positive negligible to weak correlation with the VAS (rho = 0.27; p < 0.001), Borg’s CR10 scale (rho = 0.19; p = 0.009), and the total score of GHQ-28 and its domains (rho ≤0.34; p < 0.05); and significant negative weak correlation with PF2 (rho = − 0.27; p < 0.001) and significant negative moderate correlation with PF1 (rho = − 0.35; p < 0.001), thus confirming the priori hypotheses (89%, 8/9). The internal consistency and ICC (α = 0.91; ICC = 0.80) were highly adequate, with SEM and MDC95% of 7.91 and 21.3 respectively.ConclusionsThe JRPD was successfully adapted into Persian and had adequate psychometric properties in terms of content and convergent validity, internal consistency, and test-retest reliability. The questionnaire is found useable to assess the CLBP-related biomechanical exposures in Iranian male Army personnel.

Effects of the Elevation Training Mask® 2.0 on dyspnea and respiratory muscle mechanics, electromyography, and fatigue during exhaustive cycling in healthy humans

ObjectivesExamine the effects of the Elevation Training Mask® 2.0 (ETM) on dyspnea, and respiratory muscle function and fatigue during exercise. DesignRandomized crossover. Methods10 healthy participants completed 2 time-to-exhaustion (TTE) cycling tests while wearing the ETM or under a sham control condition. During the sham, participants were told they were breathing air equivalent to “9000 ft” (matched to the selected resistance valves on the ETM according to the manufacturer), but they were breathing room air. Dyspnea and leg discomfort were assessed using the modified 0–10 category-ratio Borg scale. Qualitative dyspnea descriptors at peak exercise were selected from a list of 15. Crural diaphragmatic electromyography (EMGdi) and transdiaphragmatic pressure (Pdi) were measured via a multipair esophageal electrode balloon catheter. Participants performed maximal respiratory maneuvers before and after exercise to estimate the degree of respiratory muscle fatigue. ResultsExercise with the ETM resulted in a significant decrease in TTE (p = 0.015), as well as increased dyspnea at baseline (p = 0.032) and during the highest equivalent submaximal exercise time (p = 0.0001). The increase in dyspnea with the ETM was significantly correlated with the decrease in exercise time (r = 0.73, p = 0.020). EMGdi and Pdi were significantly increased with the ETM at all time points (all p < 0.05). There was a significant increase in the selection frequency of “my breath does not go in all the way” at peak exercise with the ETM (p = 0.02). The ETM did not induce respiratory muscle fatigue. ConclusionsExercising with the ETM appears to decrease exercise performance, in part, by increasing the sensation of dyspnea.

Effectiveness of Text Messaging as an Incentive to Maintain Physical Activity after Cardiac Rehabilitation: A Randomized Controlled Pilot Study.

Although the efficacy of cardiac rehabilitation (CR) is proven, the need to improve patients’ adherence has emerged. There are only a few studies that have investigated the effect of sending text messages after a CR period to stimulate subjects’ ongoing engagement in regular physical activity (PA). A randomized controlled pilot trial was conducted after CR, sending a daily PA text message reminder to an intervention group (IG), which was compared with a usual care control group (CG) during three months of follow-up. Thirty-two subjects were assessed pre- and post-study intervention with GPAQ, submaximal iso-watt exercise testing, a 30 s sit-to-stand test, a bilateral arm curl test, and a final survey on a seven-point Likert scale. A statistically significant difference in the increase of moderate PA time (Δ 244.7 (95% CI 189.1, 300.4) minutes, p < 0.001) and in the reduction of sedentary behavior time (Δ −77.5 (95% CI 104.9, −50.1) minutes, p = 0.004) was shown when the IG was compared with the CG. This was associated with an improvement in heart rate, blood pressure, and patients’ Borg rating on the category ratio scale 10 (CR10) in iso-watt exercise testing (all p < 0.05). Furthermore, only the IG did not show a worsening of the strength parameters in the follow-up leading to a change of the 30 s sit-to-stand test with a difference of +2.2 (95% CI 1.23, 3.17) repetitions compared to CG (p = 0.03). The telemedical intervention has been appreciated by the IG, whose willingness to continue with regular PA emerged to be superior compared to the CG. Text messages are an effective and inexpensive adjuvant after phase 2 CR that improves adherence to regular PA. Further studies are needed to confirm these results in a larger patient population and in the long term.

Continuous versus intermittent use of furosemide in patients with heart failure and moderate chronic renal dysfunction.

AimsThere is paucity of clinical data comparing continuous infusion (CI) with bolus injection (BI) of intravenous loop diuretics in patients with acute decompensated heart failure (ADHF) and chronic renal dysfunction. This study aimed to compare the efficacy and safety of CI versus BI intravenous furosemide administration in patients with ADHF and moderate chronic renal insufficiency.Methods and resultsAcute decompensated heart failure and moderate chronic renal insufficiency [with estimated glomerular filtration rate (eGFR) 15.0–44.9 mL/min/1.73 m2] were randomized to start intravenous furosemide by BI or by a 6 h CI. End points included freedom from congestion at 72 h, the degree of dyspnoea assessed using the 0–10 Borg's category ratio scale, net daily urine output, weight loss during the study, length of hospital stay, total urinary sodium excretion, and development of acute kidney injury or electrolyte disturbance. After 72 h of treatment, the rate of the primary endpoint of freedom from congestion in the CI group was significantly higher than that in the BI group (69.05% vs. 43.59%, P = 0.02). The modified Borg scale indicated patients in the CI group had lower dyspnoea score than those in the BI group at 48 h (4.29 ± 1.23 vs. 5.97 ± 1.56; P = 0.02) and 72 h (1.15 ± 0.35 vs. 2.66 ± 0.83; P = 0.003). There were other significant differences favouring the CI group with regard to net urine output at 72 h (5145.98 ± 621.37 mL vs. 3755.95 ± 456.93 mL; P = 0.007), the mean body weight loss (4.72 ± 1.01 kg vs. 3.53 ± 0.73 kg; P = 0.02) and the total urinary sodium excretion (385.05 ± 38.15 vs. 320.33 ± 37.67; P = 0.02). The length of hospitalization in the CI group was significantly shorter than that in the BI group (10.36 ± 4.20 days vs. 15.68 ± 6.15 days; P = 0.02). No significant differences were observed between groups in the frequency of acute kidney injury, tinnitus, electrolyte disturbance or mortality.ConclusionsContinuous intravenous infusion of furosemide resulted in significantly greater diuresis than bolus administration of an equal dose in patients with moderate chronic renal insufficiency and ADHF, while no differences emerged in terms of side effects or mortality.

Positive Effects of Pre-exercise Metabolic Alkalosis on Perceived Exertion and Post-exercise Squat Jump Performance in World-Class Cyclists.

Thomas, C, Delfour-Peyrethon, R, Dorel, S, and Hanon, C. Positive effects of pre-exercise metabolic alkalosis on perceived exertion and post-exercise squat jump performance in world-class cyclists. J Strength Cond Res 36(9): 2602-2609, 2022-This study aimed to determine the effects of pre-exercise alkalosis in world-class cyclists on their general (rate of perceived exertion [RPE]) and local (category-ratio scale [CR10]) perceived rates of exertion and acid-base status during 2 types of training sessions. Eight world-class cyclists ingested either sodium bicarbonate (BIC) or a placebo (PLA) in a double-blind and randomized order before performing 4 × 1,000 m constant-power sprints (CP) or 3 × 500 m all-out sprints (AO), with 20 minutes of recovery time between each session. For AO, the performance was assessed through the cycling sprint velocity and a squat jump test during recovery. During both tests, RPE, CR10, and acid-base status were measured. Sodium bicarbonate ingestion was effective in inducing pre-exercise alkalosis, compared with a PLA ( p < 0.05). During CP, performance and RPE were the same for BIC and PLA ( p > 0.05) with no time effect. The CR10 increased for the last sprint in PLA ( p < 0.05) but was attenuated in BIC (BIC: 6 vs. PLA: 8.2; p < 0.05), whereas there was no difference in acid-base status. During AO, RPE and CR10 increased with time, with no BIC effect, whereas blood lactate concentration was different ( p < 0.05). Sodium bicarbonate supplementation had no effect on overall repeated sprints ( p > 0.05). However, world-class athletes responded to BIC with higher squat jump performance than the PLA condition after AO ( p < 0.05). Our results suggest a positive influence of pre-exercise alkalosis in world-class cyclists on local perception of efforts after constant load sprints and an attenuation of muscle power output decline postsprint, as evidenced by improved squat jump performance after all-out cycling effort.

Subjective Preferences and Discomfort Ratings of Backrest and Seat Pan Adjustments at Various Speeds

Power seats (i.e., electrically adjustable seats that can be designed to move in several ways) have become increasingly common in airplanes, vehicles, and offices. Many studies have investigated the effects of seat attitude parameters, for example, the inclined angles of a backrest, on discomfort during the adjustment process. However, few studies have considered discomfort under different speeds during the adjustment process. In this study, we investigated discomfort with three speeds (i.e., “fast”, “median”, and “slow” corresponding to three durations of 15, 20, and 25 s, respectively) and two adjustments of a power seat, i.e., incline angle adjustment of the backrest and fore-and-aft position adjustment of the seat pan. We also investigated the effects of different physiological parameters on subjects’ discomfort. Twenty-four subjects (12 males and 12 females) completed a questionnaire to indicate their adjustment condition preferences, to rate their overall discomfort during the adjustment processes on a category-ratio scale, and to rate their local body discomfort. The majority of subjects preferred the fast speed adjustment condition and the trend was that a lower backrest adjustment speed increased discomfort during the process. The dominant local discomfort was in the upper and lower back regions during the backrest adjustment, whereas there was no obvious dominant local discomfort during the seat pan adjustment. The physiological parameters also had significant correlations with discomfort in some adjustment movements, for example, the discomfort was negatively correlated with height during the backrest adjustment.

A multidimensional assessment of dyspnoea in healthy adults during exercise.

(1) To determine whether healthy humans can distinguish between the intensity and unpleasantness of exertional dyspnoea; (2) to evaluate the reliability of qualitative dyspnoea descriptors during exercise; and (3) to assess the reliability of the Multidimensional Dyspnoea Profile (MDP) METHODS: Forty-four healthy participants (24M:20F, 25 ± 5years) completed maximal incremental cycling tests on three visits. During visit 1, participants rated the intensity and unpleasantness of dyspnoea simultaneously throughout exercise using the modified 0-10 category-ratio Borg scale. On visits 2 and 3, participants rated either the intensity or unpleasantness of dyspnoea alone at the same measurement times as visit 1. On all visits, participants selected qualitative descriptors throughout all exercise intensities from a list of 4, selected relevant qualitative descriptors from a list of 15 at peak exercise, and completed the MDP. Participants rated their dyspnoea intensity significantly higher for a given minute ventilation ([Formula: see text]) compared to dyspnoea unpleasantness (dyspnoea-[Formula: see text] slope: 0.08 ± 0.02 vs. 0.07 ± 0.03 Borg 0-10/Lmin-1, p < 0.001) during visit 1. The onset of intensity ratings occurred at a significantly lower work rate compared to unpleasantness ratings measured on the same exercise test (52 ± 41 vs. 91 ± 53 watts, p < 0.001). Dyspnoea intensity and unpleasantness remained significantly different for a given ventilation even when measured independently on separate exercise tests (p < 0.05). There was good-to-excellent reliability (ICC > 0.60) for the use of qualitative dyspnoea descriptors and the MDP to measure dyspnoea at peak exercise. Exercise-induced dyspnoea in healthy adults can differ in the sensory and affective dimensions, and can be measured reliably using qualitative descriptors and the MDP.

The effect of diaphragm fatigue on the multidimensional components of dyspnoea and diaphragm electromyography during exercise in healthy males

Diaphragm fatigue may increase the intensity (sensory dimension) and unpleasantness (affective dimension) of dyspnoea, which may partially explain why diaphragm fatigue negatively affects exercise performance. We hypothesized that diaphragm fatigue would negatively affect exercise performance via increases in both the intensity and unpleasantness of dyspnoea, and that the increase in dyspnoea would be mechanistically linked to an increase in diaphragmatic EMG (EMGdi ), a surrogate measure of neural respiratory drive. Fatiguing the diaphragm prior to exercise reduced cycling performance and increased both the intensity and unpleasantness of dyspnoea. The change in submaximal dyspnoea unpleasantness was significantly correlated with the change in cycling performance. Pre-fatigue of the diaphragm did not increase EMGdi during exercise and is therefore unrelated to the increase in either the sensory or affective dimension of exertional dyspnoea. The purpose of this study was to examine the effect of diaphragm fatigue on the multidimensional components of dyspnoea and diaphragm electromyography (EMGdi ) during cycling. Sixteen healthy males (age=27±5yr, =45.8±9.8mlkg-1 min-1 ) completed two high-intensity, time-to-exhaustion cycling tests in randomized order: (i) inspiratory pressure threshold loading (PTL) prior to exercise to induce diaphragm fatigue (pre-DF) and (ii) no PTL (control). Diaphragm fatigue after PTL was confirmed via cervical magnetic stimulation of the phrenic nerves. Dyspnoea intensity and unpleasantness were measured throughout exercise with the 0-10 category-ratio Borg scale and following exercise using the Multidimensional Dyspnoea Profile (MDP). EMGdi was continuously recorded via a multipair oesophageal electrode catheter. Time-to-exhaustion decreased with pre-DF vs. control (9.0±5.5 vs. 10.7±7.5min, P=0.023). Pre-DF increased dyspnoea intensity ratings by 0.6±1.0 Borg 0-10 units at the highest equivalent submaximal exercise time (HESET) a participant could achieve in both conditions (P=0.020). Dyspnoea unpleasantness ratings increased with pre-DF by 0.5±1.0, 0.7±1.2 and 0.9±1.4 (all P<0.05) Borg 0-10 units during the 2nd, 3rd and 4th minutes of exercise, respectively. There was a significant correlation between the change in breathing unpleasantness ratings at HESET and the change in time-to-exhaustion (r=0.66, P=0.006). The immediate perception domain, a combination of peak unpleasantness and specific dyspnoea descriptor intensity ratings, was the only component of the MDP that was significantly increased with pre-DF (4.3±1.9 vs. 3.6±1.8, P=0.04). There were no significant differences in EMGdi . In conclusion, diaphragm fatigue has negative effects on multiple domains of dyspnoea, which may partially explain why exercise performance decreases with it.

An empirical category-ratio scale for evaluating the subjective intensity of noise based on the comparison of estimated magnitudes and categories

In psychophysical studies, the methods of magnitude estimation (ME) and rating scale (RS) are often employed to obtain the subjective intensity of noise. Research interest has usually focused on obtaining precise growth functions to express the relation between subjective and objective magnitudes of stimuli in the ME method, or utilising proper categories for a series of stimuli in the RS method. There have been few studies concerned with the validity of the two direct scaling methods in measuring the subjective intensity of noise. This paper investigated the subjective discomfort caused by noise in the methods of relative magnitude estimation (RME), absolute magnitude estimation (AME), and RS. Forty-two participants were divided into three groups, and each group rated the discomfort caused by 22 noise stimuli at sound pressure levels from 49 to 91 dBA using RME, AME or RS method, respectively. Results indicated that the RS method yields interval scales and the ME method yields logarithmic interval scales for the discomfort of noise, so the sensory continua of noise discomfort could be described in linear relation or power function, depending on the evaluating methods. Based on the empirical data, a category-ratio scale was developed for evaluating the noise discomfort by combining the scales of AME and the scales and verbal descriptors of RS. Equations were also proposed tentatively for noise discomfort to predict the categories from the estimated magnitudes.

The Effects of Knee Joint Angle and Contractor Intensity on Perceived Exertion.

This study examined knee joint angle and knee muscle contraction intensity effects on perceived exertion during isometric contractions. Fourteen healthy young adults participated in five experimental exercise sessions in which knee angles varied randomly (10°, 30°, 50°, 70°, and 90°), each separated by one week. During each session, subjects performed five isometric maximal voluntary contractions (MVCs) of knee extension, followed by nine, randomly ordered submaximal contractions (10%-90% MVC, 10% increments). The participants repeated the identical procedure for the knee flexor muscles. Immediately following each submaximal contraction, participants rated their perceived exertion using a modified Borg category-ratio scale. We found that the participants' overall ratings of perceived exertion were significantly ( p < .05) greater at the 90° than at the 70° and 10° positions during the knee extensor contractions. There were also several significant angle by contraction intensity interactions in that perceived exertion was significantly greater across 60% to 70% MVC at 30° than at 50° ( p < .01), while the opposite pattern was observed across 70% to 80% MVC ( p < .01). During knee flexor contractions, perceived exertion was significantly greater ( p < .05) at 90°, when compared with all other knee angles. There were also significant ( p < .05) angle by contraction intensity interactions between the 50° and 70° knee positions across contraction intensities of 30-40%, 40-50%, 50-60%, and 60-70% MVC. We conclude that the higher perceived exertion rating at 90° during knee extension and flexion contractions suggests different peripheral and central contributors between both muscle groups, due to differences in muscle length.

EVALUATING PRODUCTIVITY TARGET AND ERGONOMICS SAFEGUARD: A HUMAN FACTOR STUDY OF BOTTLE MAKING INDUSTRY

This study evaluated the relationship between machinery operators’ productivity efficiency (MOPE) and the machinery operators’ on-the-job ergonomics satisfactions (MOOES) in Southwest Nigeria bottle making industry (BMI). The MOPE, for a period of one year, was computed for 50 semi-automatic PET blow machines operators in 12 bottle making industries. The subjective perceptions of the workers (category ratio scale - (CRS)) with respect to workloads elements and exposures to machine related hazards were measured using a questionnaire. MOPE results showed 78% of the studied subjects scored about 50% and their productivity were rated average. However, more than 92% of the operators suffered from mental, physical and environmental workload elements. With t- test, MOPE showed statistically significantly higher means value (54.22 ± 2.5, SEM= 1.8) compared to MOOES (34.40 ± 2.75, SEM=.125), t(98) = 23.309, p = .001 hence, were significantly different t- confirming a gap between machinery operators’ ergonomics satisfactions and their productivity levels. The study suggested development of administrative measures capable of bridging the gap to enhance health and safety of the workers. Key words: ergonomics, satisfaction, machinery, operators, productivity, bottle, industry.