Physiological and perceptual responses during walking at set and preferred pace in normal and overweight adults

BACKGROUND

This study aimed to investigate the influence of body weight, exercise modality, and pace on physiological and perceptual responses to determine the relation between perceptual and physiological responses.

METHODS

Aerobically untrained, normal weight, and overweight males and females participated. Participants were randomly assigned to one exercise condition for a 1-mile walk.

RESULTS

Prescribed pace resulted in a greater physiological stress than self-selected pace (all p < 0.001) through blood lactate (1.3 ± 0.4 vs 1.7 ± 0.5 mmol), systolic blood pressure (128.9 ± 10.3 vs 139.2 ± 13.2 mmHg), heart rate recovery (2.1 ± 1.7 vs 4.5 ± 2.6 min), oxygen consumption (15.1 ± 2.6 vs 18.1 ± 3.6 ml/kg/min), heart rate (111.7 ± 16.6 vs 134.4 ± 8.3 bpm), and energy expenditure (5.5 ± 1.4 vs 6.8 ± 1.7 kcal/min). Overweight individuals exhibited higher values than normal weight for heart rate (113 ± 8.8 vs 125.5 ± 13.2 bpm, p < 0.001), percentage of max heart rate (60.7 vs 69.0%, p < 0.001), percent of VO2peak (42.2 vs 55.6%, p < 0.001), and total energy expenditure (100.9 ± 27.4 vs 114.1 ± 33.5 kcal, p = 0.022). Greater perceived effort was seen on a treadmill (6.3 ± 0.5 vs 12.5 ± 2.0 RPE, p < 0.001) and at prescribed pace (6.5 ± 1.1 vs 8.9 ± 1.9 RPE, p < 0.001).

CONCLUSION

A novel finding of this study was the increased physiological stress and perception of effort on a treadmill and at a prescribed pace, while total energy expenditure showed no significant differences. This could indicate an unfavorable perception and less affective response to the treadmill modality. These results indicate exercise at self-selected pace in preferred environments promotes enjoyable experiences with similar health benefits as those during prescribed higher intensity exercise.

The physical activity, stress and metabolic syndrome triangle: a guide to unfamiliar territory for the obesity researcher

Research aimed at deciphering the aetiology of obesity and the metabolic syndrome remains focused on two behavioural factors, namely diet and physical activity, even though epidemiologic research suggests that these two cornerstones of treatment and prevention account for only a small-to-moderate portion of the variance in these phenotypes. In recent years, this observation has prompted the intensified investigation of the pathogenic potential of factors that extend beyond the traditional concept of energy imbalance and examine the putative causes of this imbalance. Psychosocial stress has emerged as one such factor, raising the need for researchers to be informed about this expansive and complex literature. The purpose of this review is twofold (i) To introduce obesity researchers to fundamental concepts and historically important theoretical developments in the stress field and (ii) To outline the dyadic and triadic interactions between stress, physical activity and the metabolic syndrome. Although the expansion of the research focus to multiple, diverse and interacting putative causal agents will certainly increase the complexity of the research enterprise, this step seems essential for the comprehension and effective response to the continuing rise in the prevalence of obesity and the metabolic syndrome.

Nephrobronchial fistula - a case report

We report the case of a 58-year-old woman with a hydronephrotic left kidney who presented with a 4-month history of anorexia, weight loss and intermittent left loin pain associated with cloudy urine. Her urine grew lactose fermenting coliforms, and was treated with antibiotics. A computerized axial tomography scan (CT scan) was equivocal and she underwent retrograde ureteric stenting, which drained a pyonephrosis. She went on to develop a chest infection due to a lung abscess. A CT scan revealed a left perinephric collection extending across the diaphragm into the lower lobe of the left lung. She responded to antibiotics and awaits a nephrectomy.

Mechanism of action of the novel plasma membrane Ca(2+)-pump inhibitor caloxin

Caloxin 2A1 is a novel inhibitor of the plasma membrane (PM) Ca(2+)-pump [Am. J. Physiol. Cell Physiol. 280 (2001) C1027]. The PM Ca(2+)-pump is a Ca(2+)-Mg(2+)-ATPase that expels Ca(2+) from cells to help them maintain low concentrations of cytosolic Ca(2+). Caloxin 2A1 inhibits Ca(2+)-Mg(2+)-ATPase in human erythrocyte leaky ghosts. Here we report that this inhibition is non-competitive with respect to the substrates Ca(2+) and ATP and the activator calmodulin. This was anticipated since the high affinity binding site for Ca(2+) and sites for ATP and calmodulin are intracellular whereas caloxin 2A1 is a peptide selected for binding to the second extracellular domain of the pump. Caloxin 2A1 also inhibited the Ca(2+)-dependent formation of the acid stable 140 kDa acylphosphate intermediate from 32P-gamma-ATP. However, it did not inhibit the formation of the acylphosphate intermediate in the reverse direction-from 32P-orthophosphate. Consistent with results on mutagenesis of transmembrane residues in the pump protein, we suggest that caloxin 2A1 inhibits conformational changes required during the reaction cycle of the pump.

Ascorbate transport in pig coronary artery smooth muscle: Na(+) removal and oxidative stress increase loss of accumulated cellular ascorbate

Pig deendothelialized coronary artery rings and smooth muscle cells cultured from them accumulated ascorbate from medium containing Na(+). The accumulated material was determined to be ascorbate using high-performance liquid chromatography. We further characterized ascorbate uptake in the cultured cells. The data fitted best with a Hill coefficient of 1 for ascorbate (K(asc) = 22 +/- 2 microM) and 2 for Na(+) (K(Na) = 84 +/- 10 mM). The anion transport inhibitors sulfinpyrazone and 4,4'-diisothiocyanatostilbene-2,2'-disulfonate (DIDS) inhibited the uptake. Transferring cultured cells loaded with (14)C-ascorbate into an ascorbate-free solution resulted in a biphasic loss of radioactivity - an initial sulfinpyrazone-insensitive faster phase and a late sulfinpyrazone-sensitive slower phase. Transferring loaded cells into a Na(+)-free medium increased the loss in the initial phase in a sulfinpyrazone-sensitive manner, suggesting that the ascorbate transporter is bidirectional. Including peroxide or superoxide in the solution increased the loss of radioactivity. Thus, ascorbate accumulated in coronary artery smooth muscle cells by a Na(+)-dependent transporter was lost in an ascorbate-free solution, and the loss was increased by removing Na(+) from the medium or by oxidative stress.

Lay theories of successful aging after the death of a spouse: a network text analysis of bereavement advice

Social theories of successful aging attempt to explain how individuals adapt to changes characteristically associated with aging and to predict whether older adults' adaptations will lead to successful aging. The death of a spouse and the accompanying bereavement process entail dramatic changes to personal networks and experience to which individuals must adapt to age successfully. Network text analysis (including word frequencies, cluster analysis, and multidimensional scaling) of advice for adjusting to, and coping with, the loss of a spouse given by a sample of 60 bereaved spouses (mean age = 68) at 6 points in time after the death of their marital partner (3-4 weeks to 24 months) reveal respondents' lay theories of successful aging. Thematic clusters address social positioning and qualifiers, activity, communication, time, and spousal characteristics. Results indicate respondents frame their advice as unique to their context of social relationships while providing support for activity theory and negatively addressing disengagement theory.

The use of a short distance cobalt unit in the treatment of primary skin tumours

Over an eight-year period 167 patients with primary skin tumours in difficult treatment sites have been treated using a short distance cobalt unit. The advantage of this unit over conventional superficial therapy is the lower absorption of radiation in underlying bone and cartilage. The local failure rate of 5% for basal cell carcinomas and 12% for squamous cell carcinomas is acceptable, and, of the remaining cures, there have been no problems with local necrosis and all have a good functional result.

Results of testicular tumour management bases on lymphographic staging

The results of the treatment of germ tumours of the testis between 1968 and 1975 are presented and assessed in relation to lymphographic staging. The number of patients seen was 132. The four year disease-free survival for Stage I seminoma was 100% and for Stage II 84% and for Stage I teratoma 72% and Stage II 31%. In Stage II seminoma supra diaphragmatic node metastases were only seen where node metastases had caused renal or ureteric displacement, and a case is made for selective prophylactic radiotherapy above the diaphragm. There was a relapse rate of 24% in the para-aortic nodes of Stage I teratomas where prophylactic irradiation was not given, suggesting a high incidence of occult metastases.