PubMed Health⌕ Search

Biomedical subjects

S C Glass

Publications and source records attributed to S C Glass.

6 recordsLinked to original sources
PubMed2001

Preferred exertion across three common modes of exercise training.

The use of self-selected intensities of exercise may increase adherence to exercise programs by allowing the participant more freedom to choose activities that are enjoyable. However, self-selected intensities may vary across exercise modes, and participants may not choose an intensity that is adequate to produce health benefits. The purpose of this study was to determine influence of exercise mode on self-selected exercise intensities. Eighteen subjects (12 men and 6 women) between the ages of 18 and 25 participated in this study. Preferred intensity tests were performed for 3 modes of exercise (treadmill, cycle ergometer, and stairstepper). .V(O)(2) values were obtained continuously and 1-minute averages were recorded at minutes 5, 10, 15, and 20 for each submaximal test. Comparisons were made using a repeated-measures analysis of variance (mode, time, mode x time). Scheffe's F test was used to test simple effects. There was a significant increase in the relative .V(O)(2) for all 3 modes of exercise across the 20-minute trials (p = 0.0001). Relative .V(O)(2) (%.V(O)(2)peak) increased from 52.20 to 64.71% for cycle exercise, 43.27 to 63.25% for the treadmill, and 47.16 to 61.17% for stairstepping. The average relative .V(O)(2) for the cycle ergometer (60.40 +/- 15.55%) was significantly higher (p = 0.02) than both the treadmill (53.65 +/- 18.36%) and stairstepper (54.66 +/- 11.98%). Relative heart rate (HR) (%HRR) for the stairstepper (80.21 +/- 9.67%) and the cycle ergometer (80.03 +/- 10.59%) were significantly higher than the treadmill (74.77 +/- 13.13%) (p = 0.0003). There were no significant differences in rating of perceived exertion (RPE) among the 3 modes of exercise. Similar RPE values were reported for the stairstepper (12.79 +/- 2.97), cycle ergometer (12.57 +/- 2.90), and the treadmill (12.50 +/- 2.87). The results indicate that subjects allowed to choose exercise intensity by self-selection chose work rates that were within the moderate range of American College of Sports Medicine guidelines of 50-85% .V(O)(2)max for treadmill, cycle ergometer, and stairstepping exercise.

Adolescent↗
PubMed1998

Identifying the integrated electromyographic threshold using different muscles during incremental cycling exercise.

BACKGROUND: The purpose of this study was to identify the IEMG threshold in the vastus lateralis (VL) and rectus femoris (RF) muscles during progressive, incremental exercise and to relate these thresholds to the ventilatory threshold (Tvent). METHODS: Ten men (age: 23.40 +/- 3.13 yrs, mass 76.64 +/- 8.13 kg, % fat: 8.81 +/- 2.32, VO2peak: 66.37 +/- 10.61 ml.kg.min-1) with cycling experience completed a graded exercise test on a cycle ergometer by cycling at 90 rpm using 45 watt increments at two minute intervals. Oxygen uptake was measured continuously and the IEMG activity of the VL and RF was calculated during the last 5 s of each minute. The mean for the IEMG of 6 to 7 complete pedal revolutions was used as the final value. Tvent was visually identified using the VE/VO2 and V-slope methods. The IEMG threshold for VL and RF was visually identified at the inflection point where a non-linear increase in IEMG occurred. Comparisons between Tvent and IEMG thresholds were made using dependent means "t"-tests. RESULTS: Results showed that an IEMG threshold was identified in all 10 subjects for the RF, but in only 5 of 10 subjects for the VL. However, when identified, the IEMG threshold for VL was similar to RF.VO2 at IEMG threshold for RF (3.53 +/- 0.36 L.min-1) was not significantly different from Tvent (3.36 +/- 0.42 L.min-1). CONCLUSIONS: These results show that the IEMG threshold is more consistently detected in the RF compared to VL during incremental cycling exercise. In addition, the IEMG threshold for RF was closely related to Tvent and provides an alternative means to assess the ventilatory threshold.

Adult↗
PubMed1994

Perception of effort during high-intensity exercise at low, moderate and high wet bulb globe temperatures.

The purpose of this study was to determine the effect of low, moderate and high wet bulb globe temperatures (Twbg) on cardiovascular variables and ratings of perceived exertion (RPE) during moderately prolonged, high-intensity exercise. Six subjects [four men and two women; mean (SD) age, 22.0 (1.2) years; maximum oxygen consumption (VO2peak), 51.0 (8.4) ml.kg-1.min-1] completed 30 min of exercise (80% VO2peak) on a cycle ergometer at low [14.7 (2.1) degrees C], moderate [21.0 (1.5) degrees C], and high [27.4 (2.3) degrees C] Twbg. Two additional subjects completed 20 min of exercise in the high temperature condition, but completed 30 min in the moderate and low Twbg. Heart rate (fc), blood pressure, blood lactate (La), mean skin temperature (Tsk), VO2, and RPE were measured at 10, 20 and 30 min. Results showed that fc, rate pressure product, RPE, pulmonary ventilation and ventilatory equivalent for oxygen increased (P < 0.05) across time for all conditions, while P(a) decreased across time. Tsk and fc were significantly greater across time in the high condition [35.9 (0.65) degrees C; 176 (12.6) beats.min-1] compared to the moderate [34.6 (1.5) degrees C; 170 (17.2) beats.min-1] and the low condition [31.7 (1.5) degrees C; 164 (17.1) beats.min-1]. However, there were no differences throughout exercise in RPE [high, 16.2 (2.0); moderate, 16.4 (2.2); low, 16.3 (1.9)] and VO2 across the conditions. These data suggest that RPE is closely related to metabolic intensity but is not a valid indicator of cardiovascular strain during exercise in high Twbg conditions.

Adult↗
PubMed1992

Accuracy of RPE from graded exercise to establish exercise training intensity.

The purpose of this investigation was to examine the accuracy of an exercise intensity prescription based upon perceptual responses obtained during a graded exercise test. Fifteen physically active men completed a graded exercise test (GXT) on a motor driven treadmill. Heart rate (HR), oxygen uptake (VO2), and RPE were measured each minute. An RPE intensity prescription was calculated as 75% of heart rate reserve from the GXT heart rate and RPE data. A minimum of 48 h later the subjects completed 10 min of exercise (EXT) on a level treadmill at the prescribed RPE. The subjects set the treadmill speed to elicit an exercise intensity equal to the prescribed perception of effort. There were significant mean differences (P < 0.05) in heart rate between the GXT (161.8 +/- 1.3) and EXT (154.9 +/- 4.5). However, by minute 6 the subjects were within four beats.min-1 of the target heart rate. There were no significant differences (P > 0.05) between GXT and EXT for VO2 (36.1 +/- 5.2, 33.1 +/- 6.4) and VE (64.1 +/- 10.8, 58.4 +/- 13.5) respectively. The present investigation demonstrates that a subject's perceptual response to a GXT can be used to accurately prescribe exercise intensity during level treadmill running. The intensity selected was within a typical range used for exercise prescription. The advantage of RPE as a method of exercise prescription is that an individual does not need to stop during exercise and measure a heart rate, but can make pace adjustments while exercising based solely upon the perception of effort.

Adult↗
PubMed1991

Ratings of perceived exertion among standard treadmill protocols and steady state running.

The purpose of this study was to determine if differences exist in ratings of perceived exertion (RPE) at a predetermined relative heart rate between two standard treadmill protocols and steady state exercise in a field setting. Thirty healthy male (N = 15) and female (N = 15) volunteers were maximally tested using the standard Bruce and a modified Balke (3.0 mph with 2.5% grade each two minutes) protocols. Each subject was randomly assigned to one treadmill protocol first, and then completed the second test forty-eight hours later. Within forty-eight hours following the second treadmill test, all subjects completed a field exercise trial consisting of an 800-m run. During the field trial an investigator paced each subject to an individualized target heart rate (75% maximal heart rate reserve) calculated from the treadmill tests. The total exercise time for the field trial was 4:31 +/- 0:22 and 5:36 +/- 0:47 min for the males and females, respectively. During the last 50 m of the field trial, RPE values were recorded. Comparisons of the rating of perceived exertion at the target heart rate (RPE at THR) were made using a 2-way (Gender x Trials) ANOVA with repeated measures across trials. There was a significant gender x trials interaction for RPE at THR, with males reporting significantly higher values during the treadmill tests as compared to the females (BRUCE = 13.5 +/- 1.6 vs 12.2 +/- 1.8; BLAKE = 15.9 +/- 2.3 vs 13.7 +/- 2.4). There was no difference noted between genders for RPE at THR during the field trial.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗