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Biomedical subjects

D L Blessing

Publications and source records attributed to D L Blessing.

At least 19 recordsLinked to original sources
PubMed1998

Cardiovascular and metabolic costs of forward, backward, and lateral motion.

PURPOSE: The purpose of this study was to compare the metabolic and cardiovascular responses of movement in forward (FM), backward (BM), and lateral (LM) directions. METHODS: Thirteen athletes with the following characteristics (mean +/- SD) were evaluated: age 21+/-3 yr, height 172.0+/-9.0 cm, weight 62.92+/-9.05 kg, and VO2max 54.13+/-7.42 mL x kg(-1) x min(-1). Subjects were evaluated at 80.45 and 134.08 m x min(-1). A repeated measures ANOVA was used for statistical analysis (P < 0.05). RESULTS: At 80.45 m x min(-1), the following respective VO2 mL x kg(-1) x min(-1) and heart rate (HR) beats x min(-1) responses were: FM = 12.42+/-2.29, 113+/-10; BM = 15.95+/-2.45, 132+/-16; and LM = 22.10+/-4.76, 140+/-15. Both VO2 and HR were significantly different between conditions: LM > BM > FM. At 134.08 m x min(-1), the following respective VO2 and HR responses were: FM = 27.15+/-2.51, 146+/-7; BM = 31.33+/-5.77, 168+/-11; and LM = 32.58+/-5.74, 169+/-10. At 134.08 m x min(-1) neither HR or VO2 were significantly different between LM or BM (LM, BM, > FM). Stride length and stride frequency were also significantly different between conditions. These results indicate the variation in the energy cost of FM, BM, and LM.

Adult↗
PubMed1997

Vertical impact forces during bench-step aerobics: exercise rate and experience.

The purpose of this study was to determine the effects of two bench-step exercise speeds on vertical impact forces and to explore this variable between novices, and instructors. 12 women (mean age 24 yr.) randomly performed 8-min. protocols of the "basic" bench-stepping technique and a more advanced "travel" technique at 30 and 33 cycles.min.-1. Analysis showed that the faster exercise rate yielded significantly higher vertical impact forces on a reference (B-8) step height (20.3 cm). At 33 cycles.min.-1, the instructors, and novices' responses were both higher than those at 30 cycles.min.-1. The mean peak vertical impact force ranged from 1.54 times the body weight for the novice group at 30 cycles.min.-1 to 1.87 times the body weight for instructors at 33 cycles.min.-1. A comparison of the groups' force curves showed a distinctive pattern in the loading of the impact forces. Specifically, the instructors consistently produced a transitory decrement in force prior to attaining peak force. In addition, the novices exhibited nonuniform increases in the production of vertical impact force across other step heights at the faster (33 cycles.min.-1) speed. Thus, experience with bench-step exercise may afford an ability to make uniform and force-absorbing adjustments in the resultant vertical impact forces at increased speeds.

Adult↗
PubMed1996

Injury rates and physiological changes associated with lateral motion training in females.

The purpose of this investigation was to evaluate physiological changes and injury rates associated with lateral motion (slideboard) training. Twenty-five females performed slideboard exercise 3 days per week, 1 hour each session, over a 10 week period. Eleven females served as controls. The subjects were pre and post tested via treadmill exercise to determine VO2peak. Body composition was analyzed by a seven-site skinfold equation. The slideboard subjects (SBS) were evaluated daily for injury incidence. A factorial repeated measures ANOVA (p < 0.05) revealed a significant 14% increase in VO2peak. No significant modifications were shown for body composition. The incidence of injury was 80% for Grade I injuries, 52% for Grade II injuries, 0% for Grade III injuries, and 4% for Grade IV injuries. Thus, the primary injury reports were of a Grade I and Grade II level of severity. The present injuries were largely associated with delayed onset muscle soreness (DOMS) in the medial leg musculature during the first two weeks of training. These results show that during a 10 wk training program lateral motion exercise is an effective mode for improving cardiorespiratory fitness. In addition, the risk of incurring an injury requiring medical attention appears to be quite low. However, untrained women who perform this activity at a frequency, duration, and intensity similar to the present study may experience muscle soreness during the initial period of training.

Adult↗
PubMed1996

Cross-validation of non-exercise predictions of VO2peak in women.

The purpose of this investigation was to cross-validate non-exercise (N-Ex %fat and N-Ex BMI) models for predicting VO2peak in females, and to evaluate the validity of these models in estimating fitness status, based on a < 9 METs cardiovascular fitness/health-risk criterion. Subjects were 165 females who completed the PA-R activity scale and were evaluated for VO2peak and body composition. The cross-validation statistics for the N-Ex %fat and N-Ex BMI models were: ryy' = 0.86, E = 6.3 (ml.kg-1.min-1), and ryy' = 0.81, E = 6.9 (ml.kg-1.min-1), respectively. Both models were found to accurately identify 87% of the subjects with VO2peak < 9 METs. The statistics associated with the < 9 MET criterion were: ryy' = 0.73, E = 3.4 (ml.kg-1.min-1), and ryy' = 0.80, E = 4.5 (ml.kg-1.min-1), for N-Ex %fat and N-Ex BMI, respectively. The N-Ex models yielded values similar to those reported previously (Jackson, A. S., S. N. Blair, M. T. Mahar, L. T. Wier, R. M. Ross, and J. E. Stuteville. Prediction of functional aerobic capacity without exercise testing. Med. Sci. Sports Exerc. 22:863-870, 1990). When exercise testing is not an option, the present N-Ex models provide an alternative method for predicting VO2peak in females.

Adolescent↗
PubMed1996

The physiological effects of bench/step exercise.

Recent investigation of acute cardiorespiratory responses to the current 'popularised' style of bench/step exercise has validated its use in improving aerobic physical fitness, particularly in women. However, no marked differences in relative measures of cardiorespiratory demand have been reported between men and women. Instructor data and training investigations further substantiate the effectiveness of bench/step exercise in promoting physical fitness, including upper body strength. However, the energy cost of bench/step exercise can vary dramatically. Important factors include, the selected step height, exercise rate, imposed step manoeuvre, routine format and use of hand-held weights. Hand-held weights may be more useful for men than woman. During training, bench/step exercise has been reported to yield a high incidence of grade I injury complaints, particularly in the calf and shoulder region. However, nearly 90% of these complaints were attributable to acute muscle soreness. Few serious injuries have been associated with the activity. Biomechanical research has shown that the ground reaction forces (GRF) experienced during bench stepping are lower than running and directly related to the step height and type of manoeuvre. In addition, compared with novices, instructors exhibit a moderation in the GRF pattern generated during landing. This suggests that a learning effect has occurred and that teachers yield a more consistent landing pattern. Finally, the activity may be effective in improving body composition, but a consideration of factors related to energy expenditure (e.g. exercise duration and dietary control) appear to be important in regimens prescribed for modifying body fat.

Athletic Injuries↗
PubMed1996

Exercise training in black adolescents: changes in blood lipids and Vo2max.

The purpose of this investigation was to evaluate the effects of a 15-week exercise training program on cardiovascular and blood lipid variables in black adolescents. Subjects consisted of black males with 12 of these participating in an exercise conditioning program and 5 designated as the control group participating in a team sports program. The mean +/- SD age was 12.8 +/- 0.97 yrs. Training for the exercise group was conducted 5 d.wk-1 for 15 weeks (weight training 2 d.wk-1 and aerobic training 3 d.wk-1). The following mean +/- SD significant changes were found for pre- to post-training for the exercise group (P < 0.05) with no significant change for controls: high density lipoprotein cholesterol (HDL-C) 1.11 +/- 0.18 to 1.28 +/- 0.17 (mmol.l-1), low density lipoprotein cholesterol (LDL-C) 2.73 +/- 0.74 to 2.41 +/- 0.81 (mmol.l-1), maximal oxygen uptake (VO2max) 43.7 +/- 9.4 to 48.2 +/- 9.7 (ml.kg-1.min-1), and maximal ventilation (VE max) 70.59 +/- 16.8 to 80.93 +/- 14.6 (L.min-1). In addition, no significant changes were found for blood pressure or other blood lipid parameters for either group. Results of this study show that exercise training can favorably alter blood lipid and VO2max values. Therefore, a vigorous exercise training program for young black males can favorably affect their cardiovascular risk profile.

Adolescent↗
PubMed1995

The metabolic responses of slideboard exercise in females.

Recently, slideboard exercise training has been introduced as a mode of aerobic training. The purpose of the investigation was to determine the acute cardiovascular and metabolic responses to slideboard exercise. Subjects consisted of 20 healthy females with a mean age of 26.5 +/- 7.9 years, and a VO2max of 40.8 +/- 5.6 ml.kg-1.min-1. The results of the investigation showed that 10 min of a commercially produced slideboard routine elicited mean heart rate (HR) responses ranging from 160 to 168 beats.min-1 and VO2 values of 27.5 to 33.5 ml.kg-1.min-1. A sub-group of 10 subjects was also evaluated while performing sliding exercise at different sliding rates (SR). Subjects performed the standard slide technique at metronome cadences of SR-40, SR-50, and SR-60 slide.min-1. As sliding rate increased so did HR and VO2. The subjects demonstrated mean responses of approximately 55 to 81% of VO2max for the slower to the most rapid sliding rates, respectively. Compared to treadmill exercise at the same oxygen consumption levels, the heart rates for sliding were approximately 15% higher. Slideboard exercise can be an alternative mode of aerobic training.

Adult↗
PubMed1995

A test to estimate VO2max in females using aerobic dance, heart rate, BMI, and age.

OBJECTIVE: The purpose of this investigation was to develop a sub-maximal exercise test for estimating VO2max utilizing aerobic dance. EXPERIMENTAL DESIGN: One hundred females between the ages 18 to 40 yr served as the subjects for test validation. The subjects completed a treadmill test to determine VO2max and were assessed for heart rate (HR) response to a bout of aerobic dance. The data associated with responses to treadmill exercise and the aerobic dance test, in conjunction with descriptive variables (e.g., age, BMI) were utilized in the validation of the multiple regression model. MEASURES: Reliability was determined by correlation and paired "t"-tests of the aerobic dance routine test and retest trials. The construction of the multiple regression equation, via forward entry analysis, and the cross-validation of the regression equation were completed to ensure the validity and reliability of the protocol in accurately estimating VO2max. RESULTS: Test, retest reliability for the dance-exercise routine was demonstrated (r = 0.98). Moreover, no significant differences were shown between the HR responses for the test and retest trials. The multiple regression analysis yielded a three variable multiple prediction equation for estimating VO2max (R = 0.84; SEE, 5.5 ml.kg-1.min-1). The three variables were the HR response to four min of aerobic dance (HR4), body mass index (BMI), and age (years). Cross-validation of the aerobic dance test was determined with a second group of 50 female subjects (R = 0.83; SEE, 5.5 ml.kg-1.min-1). Additionally, the application of the validation group regression equation to the cross-validation group yielded a comparable R of 0.82. Comparison of the predicted values for VO2max from both equations also yielded a highly significant invariance coefficient of 0.96. Finally, the results of "t"-tests between the observed and predicted mean values for VO2max revealed no significant difference (p > 0.05). Therefore, the final prediction equation, based on collapsing the means associated with the validation and cross validation samples (n = 150), was: VO2max (ml.kg-1.min-1) = 130.18-(0.38 * HR4)-(0.81 * BMI)-(0.27 * Age); R = 0.84, SEE = 5.5 ml.kg-1.min-1. CONCLUSIONS: These results indicate that a four minute aerobic dance test provides a valid and reliable sub-maximal protocol for estimating VO2max and providing an index of aerobic fitness in apparently healthy 18 to 40 yr old females.

Adolescent↗
PubMed1993

Iron status in women aerobic dance instructors.

This investigation evaluated the iron and nutritional status of 12 highly trained aerobic dance instructors who did not take iron supplements (ANS) and 8 who did (AS). A control group (C) consisted of 10 age matched controls. The aerobic instructors had exercised for approximately 3.8 days/wk, 56 min/session for the past 7 yrs. There were no significant differences among groups for energy intake, carbohydrate, protein, fat, nonheme iron, heme iron, or total iron intake (excluding supplemental iron). But both exercise groups had lower ferritin values than the control group. There was also a significant difference in mean cell volume (MCV), with both exercise groups having greater values than the control group. There were no differences among groups for serum iron, total iron binding capacity, transferrin saturation, hematocrit, or hemoglobin. One in three aerobic dance instructors had serum ferritin values below 12 micrograms.L-1. Results indicate that women exercise leaders have iron profiles that are similar to other groups of female athletes. The increased MCV values suggest runners' macrocytosis or an exercise induced macrocytosis.

Adult↗
PubMed1993

Comparison of cholesterol in habitually high and low active school-age children.

While risk-factor screening programs for coronary artery disease have been effective among adults, few programs are available for school-age children. 31 children were screened (16 active and 15 inactive) for cholesterol levels. The physically active group had a nonsignificantly lower mean which may reflect the small sample.

Child↗
PubMed1992

Effects of varying recovery periods on muscle enzymes, soreness, and performance in baseball pitchers.

In this study we examined the effects of varied recovery time on serum creatine kinase (CK), serum lactate dehydrogenase (LDH), muscle soreness, and pitch velocity in baseball pitchers. Ten males who had pitching experience participated in the study. After an 18-day training period, subjects pitched three simulated games. Game A and Game B were separated by four days of rest, while Game B and Game C were separated by two days of rest. CK, LDH, and muscle soreness were evaluated at the following times: before and immediately after exercise, and six, 24, 48, and 72 hours after exercise. Muscle performance was evaluated by measuring pitch velocity during the games. The CK level was elevated after each game (Game A - 249 U/l; Game B - 243 U/l; and Game C - 240 U/l); then it dropped toward baseline (p</=0.01). CK post-exercise values were not different among games A, B, and C. LDH displayed a response similar to CK; however, there was a reduction over the span of the games (p</=0.05). Muscle soreness was significantly elevated immediately after exercise (p</=0.01) compared to all other measurement times. Pitch velocity was not different among games A, B, and C. Results indicate that muscle damage, as evidenced by CK release, occurs in response to baseball pitching. However CK values, muscle soreness, and pitch velocity are not significantly affected by changes in the amount of recovery time typically scheduled between games.

Journal Article↗
PubMed1991

The cardiovascular and metabolic effects of bench stepping exercise in females.

The purpose of this investigation was to measure cardiovascular and metabolic responses to 20 min continuous bouts of "choreographed" bench stepping exercise in healthy females. Four frequently used bench heights were employed in a cross-over design: 15.2 cm (6 inches, B-6), 20.3 cm (8 inches, B-8), 25.4 cm (10 inches, B-10), and 30.5 cm (12 inches, B-12). Oxygen uptake (VO2) responses were significantly more pronounced in direct relationship to the bench height: B-12 greater than B-10 greater than B-8 greater than B-6 (P less than 0.05). Mean responses for VO2 ranged from 28.4 ml.kg-1.min-1 for B-6 to 37.3 ml.kg-1.min-1 for B-12. Interestingly, no difference was revealed for heart rate and the respiratory exchange ratio between B-12 and B-10 despite a higher VO2 for B-12 (B-12, B-10 greater than B-8 greater than B-6, P less than 0.05). The incorporation of 0.91 kg (2 lb) hand weights with exercise on the 20.3 cm bench elicited a modest but statistically significant increase in VO2 compared with no hand weights. No significant increase in VO2 was revealed for conditions that employed 0.45 kg (1 lb) hand weights. The results demonstrate that aerobic bench stepping is an exercise modality that provides sufficient cardiorespiratory demand for enhancing aerobic fitness and promoting weight loss in females.

Adult↗
PubMed1991

Alterations in dietary carbohydrate, protein, and fat intake and mood state in trained female cyclists.

Seven highly trained female cyclists (age 22 +/- 5 yr, height 165 +/- 6 cm, weight 60 +/- 5 kg, VO2max 55 +/- 6 ml.min-1.kg-1, mean +/- SD) consumed, for 1 wk each, isocaloric diets containing varying levels of carbohydrate, protein, and fat designated as low carbohydrate (LCHO), moderate carbohydrate (MCHO), and high carbohydrate (HCHO). Diets were administered in random order, and each subject consumed all three diet treatments. At the end of each weekly diet treatment, subjects rode on a cycle ergometer at 80% VO2max until fatigued. Cyclists continued light training during the diet treatments. Following each diet treatment and immediately prior to the fatiguing cycle ergometer ride, cyclists completed a Profile of Mood States (POMS) questionnaire. The POMS yields measures of tension (T), depression (D), anger (A), vigor (V), fatigue (F), and confusion (C), as well as providing a total mood score (TMS). Results indicated that subjects on LCHO had significantly (P less than or equal to 0.05) greater T, D, A, and TMS and less V compared with MCHO and HCHO. There were no significant differences between MCHO and HCHO. In the present study, LCHO in conjunction with training and exercise adversely affected the mood state of trained female cyclists as compared with MCHO and HCHO diets.

Adult↗
PubMed1989

The physiological effects of aerobic dance. A review.

Aerobic dance exercise is currently one of the most commonly practised adult fitness activities. The majority of the research pertaining to this form of exercise supports its application as a valid cardiovascular training alternative, especially for adult females if performed according to the American College of Sports Medicine (ACSM) guidelines. If, however, the participant is interested in modifying body composition, training frequency, duration, or efforts toward caloric restriction may need to be increased or altered beyond those employed in the aerobic dance training investigations. The amount of energy expended during a bout of aerobic dance can vary dramatically according to the intensity of the exercise. 'Low intensity' dance exercise is usually characterised by less large muscle activity and/or less lower extremity impact, and music of slower tempo. Dance exercise representative of this variety requires a cost of approximately 4 to 5 kcal/minute. Several trials, however, have shown that vigorous 'high intensity' aerobic dance which entails using the large muscle groups can require 10 to 11 kcal/minute. The associated training outcomes could be affected by such differences in dance exercise intensity and style.

Adult↗
PubMed1989

Effects of selected physical activities on health-related fitness and psychological well-being.

To determine the effects of participation in selected physical activities on scores of self-concept, body-cathexis and four items of health-related fitness, 88 women in university physical education service classes participated 3 hr. per week for 8 wk. in one of five activities (aerobic dance, jogging for fitness, swimming for fitness, life saving, and weight training). A total of 108 subjects participated in the study, with 20 students in health science classes serving as the controls. Few differences were noted between the activity groups and the controls on the posttest with pretest scores controlled. Specifically, joggers and aerobic dancers performed significantly more situps than did the controls, and joggers, aerobic dancers, weight trainers, and those in the lifesaving group displayed significantly greater flexibility on the sit and reach test than did the controls, on the posttest. None of the activity groups differed from the controls regarding self-esteem, body cathexis, body fat, or the step test scores at posttest.

Adaptation, Psychological↗