The effectiveness of session rating of perceived exertion to monitor resistance training load in acute burns patients

Session-rating of perceived exertion (RPE) is a method frequently utilised in exercise and sports science to quantify training load of an entire aerobic exercise session. It has also been demonstrated that session-RPE is a valid and reliable method to quantify training load during resistance exercise, in healthy and athletic populations. This study aimed to investigate the effectiveness of session-RPE as a method to quantify exercise intensity during resistance training in patients with acute burns. Twenty burns patients (mean age = 31.65 (±10.09) years), with a mean TBSA of 16.4% (range = 6–40%) were recruited for this study. Patients were randomly allocated to the resistance training (n = 10) or control group (n = 10). All patients completed a four week resistance training programme. Training load (session-RPE × session duration), resistance training session-volume and pre-exercise pain were recorded for each exercise session. The influence of; age, gender, %TBSA, exercise group (resistance training vs. control), pre-exercise pain, resistance training history and session-volume on training load were analysed using a multilevel mixed-effects linear regression. Session-volume did not influence training load in the final regression model, however training load was significantly greater in the resistance training group, compared with the control group (p < 0.001). Pre-exercise pain significantly influenced training load, where increasing pain was associated with a higher session-RPE (p = 0.004). Further research is indicated to determine the exact relationship between pain, resistance training history, exercise intensity and session-RPE and training load before it can be used as a method to monitor and prescribe resistance training load in acute burns patients.     

Measuring Exertion During Caregiving of Children and Young Adults with Cerebral Palsy Who Require Assistance for Mobility and Self-Care

ABSTRACT

Our purpose was to compare objective and subjective measures of energy exertion during caregiving tasks. Participants were primary caregivers (N = 19) of children and young adults (aged 3 –22 years) with cerebral palsy (CP) who require assistance for mobility and self-care (67% classified in level V on the Gross Motor Function Classification System). Measures of exertion were collected during two caregiving tasks: (1) transfers and (2) dressing. Objective measures included volume of oxygen (V02), heart rate (HR), and the subjective measure was a rating of perceived exertion (Borg RPE). Controlling for baseline status, perceived exertion correlated with VO2 (0.43, p < .01) and HR (0.29, p < .01) during the tasks. Caregivers with high baseline HR and VO2, had high Borg RPE scores following a task. Correlations were found between HR and VO2 during caregiving tasks (0.63, p < .01). Patterns of association with caregiver and child characteristics were similar for VO2 and Borg RPE. Subjective measures of exertion appear to capture the strain of caregiving. Understanding a caregiver's perception of exertion can guide therapists in assessing the need for equipment, pharmacological, or respite interventions.     

Physiological and perceptual responses to affect-regulated exercise in healthy young women

The purpose of the study was to objectively measure the exercise intensity associated with affective responses of “good” and “fairly good.” In Study 1, 8 active females completed 20 min of affect‐regulated exercise to feel “good” or “fairly good” (order counterbalanced) followed by an intensity replication session. On‐line gas analysis was used during the replication session to measure the physiological cost of exercising. In Study 2, 10 females completed either 3 trials of exercise to feel “good” (n = 5) or 3 trials to feel “fairly good” (n = 5). Each trial consisted of an affect‐regulated session followed by a replication session. Across studies, the intensity to feel “fairly good” was significantly higher than to feel “good.” Both intensities lay close to ventilatory threshold. The results add to evidence that women can use affect to regulate intensity and exercise at an intensity that would confer fitness and health benefits if maintained.     

Physiological strains while pushing or hauling

An experiment has been designed to compare two ways of load moving: pushing with a bar or hauling with a pelvic belt, against the same resistances, at the same speeds. This study has been carried out in the laboratory on a treadmill, using two groups: 15 healthy sedentary men and 10 endurance trained male athletes. The task consisted of pushing or hauling against the same resistance (3, 5 and 7 kg for the first group and 6, 8, 9 and 10 kg for the second) at two walking speeds (3 and 4 km · h^–1 for the first group and 3.7 and 4.7 km · h^–1 for the second). The physiological strains were studied by measuring heart rate (HR) and oxygen consumption ( ) in both experiments. In addition, perceived exertion was estimated in the second group according to a rating scale of perceived exertion (RPE). Analysis of variance showed that pushing with the arms was more strenuous than hauling with a pelvic belt with regard to HR, and RPE (P < 0.01). When resistances and speeds were grouped, the differences between pushing and hauling were equal to 3 beats · min^–1, 0.85 ml · min^–1 · kg^–1 for HR and , respectively, for the first experiment (sedentary subjects), wheras the differences were equal to 11.4 beats · min^–1, 1.66 ml · min^–1 · kg^–1 and 2.15 for HR, and RPE, respectively, for the second experiment (trained endurance athletes). In the endurance athletes, there was a parallel upward shift of the -HR linear relationship for pushing (covariance analysis, P < 0.01), which suggested that an element of static work (pushing with the upper limbs) added to the dynamic work could explain the higher physiological cost during pushing.     

Submaximal force production during perceptually guided isometric exercise

The aim of this study was to examine submaximal isometric force production guided by perceptual feelings of exertion. Thirty young adults performed isometric knee extensions on an isokinetic dynamometer. Subjects performed five different tests; the first test was the same for all subjects (standard naïve test). During the standard naïve test, subjects were asked to randomly produce force at perceived contraction intensities (25%, 50% and 75% of their maximum voluntary contraction (MVC)), with 100% MVC performed as the final intensity. All intensities, including the 100% MVC, were randomly performed in the other four tests (control tests 1 and 2, post 20% MVC and post 100% MVC tests). Post 20% MVC and post 100% MVC tests included fatiguing isometric exercise at 20% and 100% MVC respectively, which were performed prior to the test protocol. Results show that absolute peak force increased with increasing intensity (P<0.001) during all tests. During the standard naïve test, absolute peak force at 25% and 50% MVC was significantly lower (P=0.009) compared to control test 2, post 20% MVC and 100% MVC tests, and relative peak force was lower at all intensities compared to all other tests (P<0.001). Absolute and relative peak force was most accurate at 50% MVC (?12.06 N and ?2.42%, respectively). Prior fatiguing isometric exercise did not affect the subsequent perceptual response range. In conclusion, isometric force was most accurate at 25% MVC but under-produced (perceptually overestimated) during higher contraction intensities preceding a maximal voluntary contraction (100% MVC). The ability to match absolute force with target contraction intensities was most accurate at 50% MVC during all five experimental conditions and poor at opposite ends of the force domain. Furthermore, prior fatiguing isometric exercise did not have an effect on the subsequent perceptual response range.     

IMPORTANCE OF THE 'CROSSOVER' CONCEPT IN EXERCISE METABOLISM

1. The ‘crossover’ concept is a model of substrate supply during exercise which makes the following predictions. 2. Lipid is the major fuel (approximatel. 60%) for non-contracting skeletal muscle and the body at rest. 3. Energy flux, as determined by exercise intensity, is the major factor in determining the balance of substrate utilization during exercise. Thus, moderate and greater exercise intensities increase contraction-induced muscle glycogenosis and glycolysis, increase recruitment of fast-twitch muscle fibres, increase sympathetic nervous system activity and down-regulate mitochondrial fatty acid uptake. 4. Glycogen and glucose utilization scales exponentially to relative exercise power output with a greater gain in glycogen than in glucose use at high power. The relationship between free fatty acid flux and power output is an inverted hyperbola. Consequently, at high power outputs, the role of lipid oxidation is diminished. 5. Factors such as endurance training, energy supply, as influenced by dietary manipulation, and prior exercise play secondary roles in determining the balance of substrate utilization durin. exercise. 6. Comparisons of the metabolic responses in subjects engaged in activities requiring vastly different metabolic rates or comparisons of subjects of different gender, age or training status require normalization of dat. to total energy flux.     

Lifetime physical activity and the risk of breast cancer: a case-control study

BACKGROUND: The association between breast cancer and lifetime histories of physical activity was studied to determine whether exercise may reduce development of this cancer. METHODS: The case-control study was based on 250 women living in the Region of Western Pomerania with histological confirmed breast cancer operated during 1999-2003 in the Szczecin hospitals, and 301 controls, free of any cancer diagnosis, aged 35-75 years. Physical activity was assessed using a self-administered questionnaire with questions on type of activity, duration, frequency, and intensity for each type of activity. Data on physical activity from exercise/sports, household and outdoor chores, and occupational activity separately throughout a woman's lifetime were collected. Recreational physical activity was examined for the four age periods (14-20, 21-34, 35-50, and after the age of 50 years). Logistic regression was used to compute odds ratios (ORs) and 95% confidence intervals (CI) and a full assessment of confounding was included in analysis. RESULTS: Lifetime total physical activity among all women was associated with a reduced breast cancer risk; after controlling for potential confounders the multivariate ORs associated with <110, 110-150, and >150 metabolic equivalent (MET)-hours/week/year were 1.00 (referent), 0.60 (95% CI: 0.60-1.06), and 0.43 (95% CI: 0.25-0.75), respectively (P(trend)=0.004). Analyses by type of lifetime activity for household and recreational activities revealed significant risk reductions: 1.00 (referent); 0.51, 95% CI: 0.29-0.87; 0.54, 95% CI: 0.31-0.94 (P(trend)=0.002), and 1.00 (referent); 0.54, 95% CI: 0.31-0.94; 0.40, 95% CI: 0.22-0.70 (P(trend)<0.001), respectively. For lifetime occupational activity a modest association could not be ruled out when measured the activity by average annual hours/week; the ORs were 0.51, 95% CI: 0.29-0.91, and 0.58, 95% CI: 0.33-1.00, the inverse trend in risk was not significant (P(trend)=0.51). Women who started recreational activity after age of 20 years had much more higher breast cancer risk than either those who were active between ages 14 and 20 years and were inactive after age 20 years or continued their activity throughout adult life. CONCLUSIONS: These data are in concordance with the hypothesis that lifetime total physical activity is associated with decreased breast cancer risk. They also suggest that recreational physical activity at ages 14-20 years is the most beneficial. In addition, these findings confirm the majority of previous reports which implicated physical inactivity as important risk factor for breast cancer.     

Maximum Weights of Handling Acceptable to People Aged 55–74 Years: Part I. Lifting

The primary objective of this work was to investigate dynamic psychophysical (acceptable) material handling strengths (capabilities) of an older population (aged 55–74 years; n = 20). The findings are presented in two parts. Part I deals with manual lifting capabilities; Part II deals with manual carrying capabilities. In order to determine dynamic psychophysical strengths, routine everyday tasks were simulated in the laboratory. Lifting activities simulating work-related tasks included eight sequences of lifting (two lifting heights × four lifting frequencies); for each sequence, the maximum acceptable weight of lift (MAWL) was determined. Psychophysical lifting strengths of a younger population (18–35 years; n = 20) were also determined to find how the MAWL of the older population differed from that of the younger population. In addition to the MAWL, a number of responses at the MAWL were recorded: heart rate (HR), oxygen uptake (VO₂), and category-ratio ratings of perceived exertion (CRRPE). The results indicated no practically significant age-related differences in responses between either the older and younger males, or older and younger females. Based on the limited data collected in this study, it appears that age has no significant influence on people's capability to lift loads. Consequences of these findings on design are discussed.     

Effects of ingesting low glycemic index carbohydrate food for the sahur meal on subjective,metabolic and physiological responses,and endurance performance in Ramadan fasted men

Purpose: To investigate the effect of low glycemic index (LGI) carbohydrate meal on subjective, metabolic and physiological responses, and endurance performance in the Ramadan fasted state. Methods: During Ramadan, 12 Muslim men, in a randomized and crossover design, ingested for the sahur meal (i.e. last meal before commencement of the day’s fast), either LGI (glycemic index?=?37) or mixed (CON; ～57) meal of equivalent macro-nutrient. At ～12?h post-prandial, subjects completed a 60?min continuous run. Results: There were no significant differences between the two meals for ratings in perceived satiety, fullness, appetite and mood states. During steady-state exercise, there were no significant differences in metabolic and physiological measures. In the time-trial, distance ran was significantly lower in LGI versus CON meal trial, but with a corresponding lower perceived exertion in the LGI trial. Conclusion: Compared to CON, ingesting LGI as the sahur meal did not provide any metabolic, physiological or performance benefits during endurance run performed 12?h post-prandial in Ramadan fasted state.     

Effect of sodium hydroxybutyrate on the ammonia content in rat muscles during physical exertion

In experiments on rats forced to swim while carrying a load, sodium hydroxybutyrate was found to have a normalizing effect on the ammonia content in the striated muscles, a biochemical indicator of physical fatigue. Whereas in control rats not receiving hydroxybutyrate swimming led to a marked (more than twofold) increase in the ammonia content in muscle tissue, in animals receiving prophylactic sodium hydroxybutyrate (one only or as a 2-week course) ammonia did not accumulate. It is suggested that by preventing the toxic effect of one of the end products of nitrogen metabolism, sodium hydroxybutyrate may alleviate the after-effects of muscular fatigue.Laboratory of Pharmacology of the Nervous System, Institute, of Pharmacology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Zakusov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 89, No. 1, pp. 25–27, January, 1980.