Circulatory and thermal adjustments to prolonged exercise in paraplegic women.

The circulatory and thermal responses to 90 min of wheelchair ergometer exercise were examined in five wheelchair dependent (WD) women with low level spinal dysfunction and five able-bodied (AB) women who served as a comparison group. Metabolic rate during exercise was 221 W for WD and 255 W for AB (P greater than 0.05). Oral temperature (Tor), mean skin temperature (Tsk), oxygen uptake (VO2), heart rate (HR), and cardiac output (Qc) were assessed periodically throughout the exercise period. Ambient conditions were 24-25 degrees C and 38-52% relative humidity. A significant group X time interaction was found for Tor (P less than 0.001) and Tsk (P less than 0.001). Tor of the WD group steadily increased during the exercise, whereas the AB group showed a stable Tor. Tsk of WD increased rapidly during the first 5-10 min of exercise and continued to rise at a slower rate throughout the exercise. In contrast, Tsk of AB rose to a peak during the first 10 min and then showed a decreasing trend. VO2 and HR remained stable in both groups throughout the exercise period. Following an initial increase in Qc from minute 10 to minute 20 in both groups, values for WD continually decreased until Qc at 80 min was 14% lower than at 10 min. The findings suggest that the WD women had greater thermoregulatory strain than the AB women as indicated by a higher Tor and Tsk and by an inability to maintain Qc due to paralysis of the lower limbs and perhaps an increase in cutaneous blood volume.

Circulatory and metabolic responses of women to arm crank and wheelchair ergometry.

This study compared the circulatory and metabolic responses of arm crank ergometer (ACE) exercise to those of wheelchair ergometer (WCE) exercise during maximal and submaximal intensities. Maximal intensity exercise was defined as the highest power output (PO) achieved on each ergometer. The submaximal responses were compared at an equivalent absolute (PO = 25W) and relative (66% peak oxygen uptake [VO2]) intensity. On separate days and in random sequence, nine untrained able-bodied women performed a discontinuous incremental test for peak VO2 using either ACE or WCE. Each exercise bout was approximately six minutes, interspersed with four-minute rest periods. VO2 and heart rate (HR) were measured during each stage of the test and blood lactate concentrations were measured five minutes postexercise. Peak PO, ventilation (VE), and HR were significantly higher (p less than 0.05) on the ACE, with no significant difference in peak VO2 or postexercise blood lactate concentration. When compared at equivalent submaximal PO levels (25W), VO2, VE, and HR were significantly higher (p less than 0.05) on the WCE than on the ACE. In contrast, ACE exercise elicited a higher PO (p less than 0.05) at an equivalent relative metabolic load (66% peak VO2). These results suggest that in women wheelchair ergometry is less metabolically efficient than arm crank ergometry at submaximal exercise intensities. However, at maximal intensity exercise, ACE exercise imposes greater central circulatory stress. The finding that a higher peak HR was elicited by the ACE than the WCE suggests that exercise testing needs to be ergometer-specific when the results are to be used for exercise prescription.

Lean body mass estimation by bioelectrical impedance analysis: a four-site cross-validation study.

This study validated further the bioelectrical impedance analysis (BIA) method for body composition estimation. At four laboratories densitometrically-determined lean body mass (LBMd) was compared with BIA in 1567 adults (1069 men, 498 women) aged 17-62 y and with 3-56% body fat. Equations for predicting LBMd from resistance measured by BIA, height, weight, and age were obtained for the men and women. Application of each equation to the data from the other labs yielded small reductions in R values and small increases in SEEs. Some regression coefficients differed among labs but these differences were eliminated after adjustment for differences among labs in the subjects' body fatness. All data were pooled to derive fatness-specific equations for predicting LBMd: the resulting R values ranged from 0.907 to 0.952 with SEEs of 1.97-3.03 kg. These results confirm the validity of BIA and indicate that the precision of predicting LBM from impedance can be enhanced by sex- and fatness-specific equations.

The effects of arm crank training on the physiological responses to submaximal wheelchair ergometry.

The purpose of this investigation was to examine the cardiovascular and metabolic effects of a 5 wk arm crank (AC) training program on submaximal wheelchair (WC) ergometry in able-bodied women. The 6 subjects in the training group (TG) and 4 in the control group (CG) performed a 10 min WC exercise prior to and following the training period at a power output (PO) that elicited 70% of the pre-training peak oxygen uptake (VO2). Steady state VO2, heart rate (HR), cardiac output (Qc) and stroke volume (Vs) were measured. Resting and post-exercise blood lactate concentrations (LA) were measured, the difference was recorded as net LA. The TG exercised on the AC 3 d.wk-1 at a PO that elicited 85% of each subject's recorded peak HR. Each session consisted of four 4 min exercise bouts preceded by a 2 min warm-up and interspersed with 2 min rest periods. After training, the TG had a significantly (p less than 0.05) lower HR, larger Vs and lower LA in response to the WC exercise. Qc and VO2 were not significantly altered. The results demonstrate that the AC exercise program used in this study produced a physiological training effect which was observed during submaximal WC exercise of an intensity frequently encountered during daily WC ambulation. It appears that short-term, moderate intensity AC training offers an adequate stimulus to reduce the stress imposed by wheelchair locomotion.

The mechanical efficiency of wheelchair dependent women during wheelchair ergometry.

Few previous studies have attempted to study the response of disabled women to work in a wheelchair. The purpose of this study was to investigate the mechanical efficiency of wheelchair dependent women (WCD) during progressively loaded wheelchair ergometry. Five WCD subjects with an average confinement of 17.8 years were compared to five able bodied women (AB). Neither maximal oxygen uptake, 1.121 WCD and 1.485 AB (L X min-1) or maximal power outputs, 41.6 WCD and 44.1 AB (watts) were significantly different for the groups. The WCD group, however, demonstrated significantly higher mechanical efficiencies at comparable power outputs, p greater than 0.05. This difference remained when comparisons at about 60, 80, and 90% of VO2 max were made. The average efficiencies over these metabolic levels were 14% WCD and 10.6% AB. Stroke length consistently reduced as power outputs increased with the values lower for the WCD subjects. Average values for the submaximal workloads were 3.17 WCD and 3.76 AB (m x stroke-1) which meant a difference that was 18.6% greater in length for the AB group. The possible influence of this upon the efficiency of wheelchair locomotion was discussed.

Alactic capacity and power: reliability and interpretation.

The purpose of this investigation was to determine test-retest reliability for measuring maximal values of alactic capacity (ALCmax) and alactic power (ALPmax). For this, 31 men and 13 women each completed two ALCmax and ALPmax tests. Test-retest correlation coefficients for ALCmax and ALPmax values were 0.78 and 0.90, respectively. In addition, for both variables no significant differences were found between test no. 1 and test no. 2. Mean ALCmax values of 429 and 317 J . kg-1, as well as mean ALPmax values of 3.79 and 3.08 W . kg-1 were found for the men and women, respectively. Both ALCmax and ALPmax values were lower (p less than 0.05) for women than men. However, for the capacity power ratio (ALCmax . ALPmax-1) no difference was found between men and women. A correlation coefficient of r = 0.61 was found between mean values for ALCmax and ALPmax . ALCmax values were discussed as being related to skeletal muscle phosphagen concentrations, and ALPmax values were discussed as being related to phosphagen splitting rate. The observed sex differences were suggested to reflect a greater percent body fat in women than men.

Physiological and performance characteristics of United States championship class orienteers.

The purpose of this investigation was to study the anaerobic and aerobic power of female and male United States championship orienteers and relate these data to competitive performance. In addition, it was considered valuable to obtain a general physical description of the athletes. Anthropometrically, neither the females (n=5) nor the males (n=13) conformed to a somatotype classification typical of endurance athletes. Although the mean anaerobic power values for the females (76.6 kg.m.sec-1) and the males (106.6 kg.m.sec-1) were consistent with what is known for distance runners, the respective aerobic powers of 46.1 and 61.6 ml.kg-1.min-1 were considerably below expectations for national class competitors. The explanation for this latter finding was attributed to their reported training programs. Partial residual plots and multiple regression procedures were used to determine the relationship between aerobic power and gender, respectively, with speed of competitive performance. The final equation to predict performance was P = -13.10 + 0.62(VO2max) + 0.26 (Experience, years) - 0.03 (Anaerobic power) + 1.21 (gender) - 0.01 (VO2max)2 with an R-square of 0.73 and P less than 0.01.