Standards and predicted values of anaerobic threshold

Mean values for body size, body composition and endurance indices have been obtained from a homogeneous group of 125 physically active men to find predicted values of AT (age 23.4 +/- 4.3 years; height 175.9 +/- 6.5 cm; weight 72.2 +/- 8.9 kg; body fat 17.9 +/- 4.7% body weight, muscularity index 19.0 +/- 1.5 kg fat-free mass/cm2 X 10(-4) height; forced vital lung capacity 5667 +/- 815 cm3; VO2max 48.5 +/- 6.0 cm3 X kg-1 X min-1; anaerobic threshold 61.0 +/- 7.8% VO2max). Endurance performance and fitness indices were a little higher than average, but about 10% lower than in endurance-trained athletes. The authors suggest that standards of anaerobic threshold (AT) for ergonomics and endurance training should be about 55-65% VO2max, but not lower than 1800 cm3 O2 X min-1. The coefficients of correlation of AT relating to VO2max, PFO2 and submaximal load were significant at the 0.01 level. Using regression analysis, predicted values of AT were developed. A predicted value of AT can be obtained from the regression line of AT on Lsubmax used as a nomogram, during a simple PWC170 exercise test without blood or gas analysis.     

Validity of VO(2 max) in predicting blood volume: implications for the effect of fitness on aging

A multiple regression model was constructed to investigate the premise that blood volume (BV) could be predicted using several anthropometric variables, age, and maximal oxygen uptake (VO(2 max)). To test this hypothesis, age, calculated body surface area (height/weight composite), percent body fat (hydrostatic weight), and VO(2 max) were regressed on to BV using data obtained from 66 normal healthy men. Results from the evaluation of the full model indicated that the most parsimonious result was obtained when age and VO(2 max) were regressed on BV expressed per kilogram body weight. The full model accounted for 52% of the total variance in BV per kilogram body weight. Both age and VO(2 max) were related to BV in the positive direction. Percent body fat contributed <1% to the explained variance in BV when expressed in absolute BV (ml) or as BV per kilogram body weight. When the model was cross validated on 41 new subjects and BV per kilogram body weight was reexpressed as raw BV, the results indicated that the statistical model would be stable under cross validation (e.g., predictive applications) with an accuracy of +/- 1,200 ml at 95% confidence. Our results support the hypothesis that BV is an increasing function of aerobic fitness and to a lesser extent the age of the subject. The results may have implication as to a mechanism by which aerobic fitness and activity may be protective against reduced BV associated with aging.     

Development of a submaximal test to predict elliptical cross-trainer VO2max

The purpose of this study was to develop an equation to predict VO2max from a submaximal elliptical cross-trainer test. Fifty-four apparently healthy subjects (25 men and 29 women, mean +/- SD age: 29.5 +/- 7.1 years, height: 173.3 +/- 12.6 cm, weight: 72.3 +/- 7.9 kg, percent body fat: 17.3 +/- 5.0%, and elliptical cross-trainer VO2max: 43.9 +/- 7.2 ml x kg(-1) x min(-1)) participated in the study and were randomly assigned to an original sample group (n = 40) and a cross-validation group (n = 14). Each subject completed an elliptical cross-trainer submaximal (3 5-minute submaximal stages) and a VO2max test on the same day, with a 15-minute rest period in between. Stepwise multiple regression analyses were used to develop an equation for estimating elliptical cross-trainer VO2max from the data of the original sample group. The accuracy of the equation was tested by using data from the cross-validation group. Because there was no shrinkage in R2 between the original sample group and the cross-validation group, data were combined in the final prediction equation (R2 = 0.732, standard error of the estimate = 3.91 ml x kg(-1) x min(-1), p < 0.05): VO2max = 73.676 + 7.383(gender) - 0.317(weight) + 0.003957(age x cadence) - 0.006452(age x heart rate at stage 2). The correlation coefficient between the predicted and measured VO2max values was r = 0.86. Dependent t-tests resulted in no significant differences (p > 0.05) between predicted (43.8 ml x kg(-1) x min(-1)) and measured (43.9 ml x kg(-1) x min(-1)) VO2max measurements. Results indicate that the protocol and equation developed in the current study can be used by exercise professionals to provide acceptably accurate estimates of VO2max in non-laboratory-based settings.     

Relation between cardiorespiratory fitness and selected risk factors for coronary heart disease in a population of Canadian men and women.

OBJECTIVE: To determine the relation between cardiorespiratory fitness, as determined with the Canadian Aerobic Fitness Test (CAFT), and selected risk factors for coronary heart disease (CHD) in a Canadian population. DESIGN: Cross-sectional study. On the basis of age-specific and sex-specific national percentile scores, subjects were classified as being in the low-fitness, moderate-fitness or high-fitness category according to maximum oxygen consumption (VO2 max) predicted from performance on the CAFT. PARTICIPANTS: A total of 4082 male and 1205 female Canadian federal public servants aged 30 to 59 years who participated in a voluntary fitness testing program between 1984 and 1991. OUTCOME MEASURES: Body composition (body mass index, triceps skinfold thickness, sum of four skinfold measurements, predicted percentage of body fat and waist-hip ratio), blood lipid levels (total cholesterol, triglycerides, high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol and ratio of total cholesterol to HDL-C) and hemodynamic measurements (heart rate and blood pressure at rest and during exercise and predicted VO2 max). MAIN RESULTS: For both men and women the mean anthropometric measurements, blood lipid levels and blood pressure measurements at rest and after exercise were significantly associated with fitness category (p less than 0.05). CONCLUSIONS: In both men and women a higher level of aerobic fitness, as defined by VO2 max predicted from performance on the CAFT, is associated with a more favourable CHD risk profile. The results support the use of VO2 max predicted from performance on the CAFT as a valid procedure for classifying people according to fitness level.     

Cardiorespiratory fitness predicts changes in adiposity in overweight Hispanic boys

We have previously shown that cardiorespiratory fitness predicts increasing fat mass during growth in white and African-American youth, but limited data are available examining this issue in Hispanic youth. Study participants were 160 (53% boys) overweight (BMI>or=85th percentile for age and gender) Hispanic children (mean+/-s.d. age at baseline=11.2+/-1.7 years). Cardiorespiratory fitness, assessed by VO2max, was measured through a maximal effort treadmill test at baseline. Body composition through dual-energy X-ray absorptiometry and Tanner stage through clinical exam were measured at baseline and annually thereafter for up to 4 years. Linear mixed models were used to examine the gender-specific relationship between VO2max and increases in adiposity (change in fat mass independent of change in lean tissue mass) over 4 years. The analysis was adjusted for changes in Tanner stage, age, and lean tissue mass. In boys, higher VO2max at baseline was inversely associated with the rate of increase in adiposity (beta=-0.001, P=0.03); this effect translates to a 15% higher VO2max at baseline resulting in a 1.38 kg lower fat mass gain over 4 years. However, VO2max was not significantly associated with changes in fat mass in girls (beta=0.0002, P=0.31). In overweight Hispanic boys, greater cardiorespiratory fitness at baseline was protective against increasing adiposity. In girls however initial cardiorespiratory fitness was not significantly associated with longitudinal changes in adiposity. These results suggest that cardiorespiratory fitness may be an important determinant of changes in adiposity in overweight Hispanic boys but not in girls.     

Determinants of insulin-stimulated glucose disposal in middle-aged, premenopausal women

Controversy exists regarding the relative importance of adiposity, physical fitness, and physical activity in the regulation of insulin-stimulated glucose disposal. To address this issue, we measured insulin-stimulated glucose disposal [mg. kg fat-free mass (FFM)(-1). min(-1); oxidative and nonoxidative components] in 45 nondiabetic, nonobese, premenopausal women (mean +/- SD; 47 +/- 3 yr) by use of hyperinsulinemic euglycemic clamp (40 mU. m(-2). min(-1)) and [6,6-2H2]glucose dilution techniques. We also measured body composition, abdominal fat distribution, thigh muscle fat content, maximal oxygen consumption (VO2 max), and physical activity energy expenditure ((2)H(2)(18)O kinetics) as possible correlates of glucose disposal. VO2 max was the strongest correlate of glucose disposal (r = 0.63, P < 0.01), whereas whole body and abdominal adiposity showed modest associations (range of r values from -0.32 to -0.46, P < 0.05 to P < 0.01). A similar pattern of correlations was observed for nonoxidative glucose disposal. None of the variables measured correlated with oxidative glucose disposal. The relationship of VO2 max to glucose disposal persisted after statistical control for FFM, percent body fat, and intra-abdominal fat (r = 0.40, P < 0.01). In contrast, correlations of total and regional adiposity measures to insulin sensitivity were no longer significant after statistical adjustment for VO2 max. VO2 max was the only variable to enter stepwise regression models as a significant predictor of total and nonoxidative glucose disposal. Our results highlight the importance of VO2 max as a determinant of glucose disposal and suggest that it may be a stronger determinant of variation in glucose disposal than total and regional adiposity in nonobese, nondiabetic, premenopausal women.     

Fitness levels of firefighter recruits before and after a supervised exercise training program

Federal law prohibits pre-employment physical examination of firefighter recruits, but these workers must perform intense exercise in arduous environments. Components of physical fitness of rookie firefighters (n = 115; 104 men, mean +/- SD: age = 28.3 +/- 4.3 years; height = 1.76 +/- 0.07 m; weight = 83.2 +/- 13.9 kg; percent body fat = 17 +/- 8%) were measured upon being hired and following a 16-week exercise training program (1 h.d(-1), 3 d.wk(-1)) designed to improve physical fitness. Maximum aerobic capacity (VO2max) was estimated from submaximal cycle ergometry, body composition from skinfold tests, flexibility from a sit and reach test, strength by hand grip dynamometry, and muscle endurance by a push-up test. The results are as follows (*, p 相似文献   

Relationship between physiological profiles and on-ice performance of a National Collegiate Athletic Association Division I hockey team

Ice hockey is a game that relies heavily on both aerobic and anaerobic energy production systems as players perform in various game situations. However, we found no studies evaluating the relationship between a player's physical condition and individual success in games throughout a competitive hockey season. The purpose of this study was to determine the relationship between a player's aerobic fitness (VO(2)max), blood lactate, and percent body fat to his total minutes played during a season (Tmin) and net scoring chances (SCn). Players' (N = 29) preseason VO(2)max, lactate at the fourth stage of an incremental treadmill test (Lac 4), and percent body fat values from the 1999- 2001 National Collegiate Athletic Association Division I hockey seasons were archived and retrieved for this study. The players' Tmin and SCn were used as the on-ice performance variables and were compared with their fitness measures. Lactate at 4th treadmill stage (r = 0.41, p < 0.03) and percent body fat (r = 0.39, p < 0.03) but not VO(2)max (r = 0.20, p < 0.24) were significantly related to Tmin. Both Lac 4 and percent body fat were entered into a stepwise regression model that accounted for 25% of the variance in Tmin among players (p < 0.02). Both VO(2)max (r = 0.41, p < 0.03) and Lac 4 (r = 0.33, p < 0.05) were significantly related to the players' SCn, but percent body fat was not (r = 0.10, p < 0.57). Only VO(2)max significantly predicted the players' SCn, accounting for 17% of the variance. These findings suggest a relationship between a player's conditioning level and on-ice performance. Our results support the value of implementing seasonal physiological testing, which will help strength and conditioning coaches make individualized modifications to a player's fitness regimens in an effort to improve specific physiological attributes.     

Measuring aerobic cycling power as an assessment of childhood fitness

The emergence of obesity, insulin resistance, and type 2 diabetes in children requires a rational, effective public health response. Physical activity remains an important component of prevention and treatment for obesity, type 2 diabetes, and insulin resistance. Studies in adults show cardiovascular fitness to be more important than obesity in predicting insulin resistance. We recently demonstrated that a school-based fitness intervention in children who are overweight could improve cardiovascular fitness, body composition, and insulin sensitivity, but it remains unclear whether accurate assessment of fitness could be performed at the school or outside of an exercise laboratory. To determine whether new methodology using measurement of cycling power could estimate cardiovascular aerobic fitness (as defined by VO2max) in middle school children who were overweight. Thirty-five middle school children (mean age 12 +/- 0.4 years) who were overweight underwent testing on a power sensor-equipped Cycle Ops indoor cycle (Saris Cycling Group, Fitchburg, WI) as well as body composition by dual x-ray absorptiometry and VO2max by treadmill determination. Insulin sensitivity was also estimated by fasting glucose and insulin. Maximal heart rate (MHR) was determined during VO2max testing, and power produced at 80%MHR was recorded. Spearman's rank correlation was performed to evaluate associations. Mean power determined on the indoor cycle at 80% of MHR was 129 +/- 77 watts, and average power at 80% MHR divided by total body weight was 1.5 +/- 0.5. A significant correlation between watts and total body weight was seen for VO2max (P = 0.03), and significant negative correlation was seen between watts/total body weight and fasting insulin (P < 0.05). Among middle school children who were overweight, there was a significant relationship between the power component of fitness and cardiovascular aerobic fitness (measured by VO2max). This more accessible and less intimidating field-based measure of power may prove useful in predicting changes in cardiovascular fitness. Thus, accurate assessment of childhood aerobic fitness may be achievable by measurement of power, possibly within the school environment, at substantially less cost and effort than laboratory-based measurements.     

Effect of prolonged training period on plasma adiponectin in elite male rowers.

Adiponectin is secreted by adipocytes and has been implicated in the regulation of energy homeostasis. Vigorous training program represents a physical stress condition in which heavy changes in energy expenditure might increase adiponectin concentration in athletes. Therefore, the aim of the present study was to investigate if there are changes in fasting adiponectin concentration during preparatory period in elite male rowers. Twelve rowers (mean and SD; age: 20.8+/-3.0 years; height: 192.9+/-4.7 cm; body mass: 91.9+/-5.3 kg; body fat percentage: 11.9+/-1.4%) were tested seven times over a 24-week training season. In addition to adiponectin, leptin, insulin, growth hormone, and glucose values were evaluated. Maximal oxygen consumption (VO (2 max)) and aerobic power (Pa (max)) were determined before and after the training period. Training was mainly organized as low-intensity prolonged training. Significant increases in VO (2 max) (by 3.2+/-1.8%; from 6.2+/-0.5 to 6.4+/-0.4 l/min), VO (2 max/kg) (by 2.2+/-2.0%; from 67.9+/-3.0 to 69.4+/-3.0 ml/min/kg) and Pa (max) (by 4.6+/-6.3%; from 444.6+/-39.1 to 465.8+/-25.0 W) were observed after the 24-week period. All measured body compositional values were similar to pretraining values after the training period. Fasting adiponectin did not change during the preparatory period. Likewise, leptin, insulin, growth hormone, and glucose values were not significantly changed after the training period. Adiponectin concentration was significantly correlated (all p<0.05) with body mass (r=-0.40), body fat mass (r=-0.33), body fat free mass (r=0.38), and leptin (r=-0.31) values. In conclusion, fasting adiponectin does not change throughout the prolonged training period in elite male rowers despite substantial changes in training volume. Further studies are needed to clarify possible mechanisms by which adiponectin might influence energy homeostasis during heavy training in elite athletes.     

Impact of body composition on performance in fitness tests among personnel of the Croatian navy

The purpose of this study was to determine the impact of body weight on fitness tests among the personnel of the Croatian navy. Forty two naval personnel (age 27 +/- 4.1 years; body mass 86.2 +/- 4.9 kg; height 184.6 +/- 7.4 cm; body fat percentage 17.3 +/- 5.2) participated in this study. In order to evaluate the fitness of the naval servicemen, we applied a testing procedure that included measurements of 7 fitness tests and 15 body anthropometric tests. A negative correlation was found between the body fat percentage and all the analyzed sprint tests and three anaerobic power tests (r), SP5 (r = -0.42), SP10 (r = -0.51), SP20 (r = -0.53), SJ (r = -0.45), CM (r = -0.57), SLJ (r = -0.67). Also a negative correlation was found between the body fat percentage and VO2(max) (r = -0.44). A positive correlation was found between the sprint test and the power performance test and thigh and calf girth. Spiriting ability is influenced by the strength of a person. This is one of the reasons why we found a positive correlation between the sprint test (SP5, SP10 and SP20) and thigh and calf girth. In this study we found a negative correlation between body fat percentages and all the sprint tests and three anaerobic power tests and VO2(max). The ectomorph somatotypes have positive correlations with all variables. The mesomorph somatotypes have the greatest positive correlations with all variables. The endomorph somatotypes have negative correlations with all variables. According to the body composition of Croatian naval servicemen we can conclude that they need a sufficient level of strength and endurance for everyday tasks. The effectiveness of a weight-management program is determined by the success of the participants in losing the necessary amount of weight and being able to maintain that weight loss. This requires long-term tracking of these individuals in a naval environment.     

Measuring aerobic cycling power as an assessment of childhood fitness

The emergence of obesity, insulin resistance (IR), and type-2 diabetes (T2DM) in children requires a rational, effective public health response. Physical activity remains an important component of prevention and treatment for obesity, T2DM, and IR. Studies in adults show cardiovascular fitness (CVF) to be more important than obesity in predicting IR. We recently demonstrated that a school-based fitness intervention in children who were overweight can improve cardiovascular fitness, body composition, and insulin sensitivity, but it remains unclear whether accurate assessment of fitness could be performed at the school or outside of an exercise laboratory. The purpose of the study was to determine if a new methodology using measurement of cycling power could estimate cardiovascular aerobic fitness (as defined by maximum oxygen consumption; VO(2)max) in middle school children who were overweight. Thirty-five middle school children who were overweight (mean age 12 +/- 0.4 years) underwent testing on a power sensor- equipped Cycle Ops Indoor Cycle (IC), as well as body composition by dual x-ray absorptiometry (DXA), and VO(2)max by treadmill determination. Insulin sensitivity was also estimated by fasting glucose and insulin. Maximal heart rate (MHR) was determined during VO(2)max testing, and power produced at 80% of MHR was recorded. Spearman's rank correlation was performed to evaluate associations. Mean power determined on the IC at 80% of MHR was 129 +/- 77 watts, and average power at 80% MHR divided by total body weight (TBW) was 1.5 +/- 0.5. A significant correlation between watts/TBW was seen for VO(2)max (ml/kg/min) (p = 0.03), and significant negative correlation was seen between watts/TBW and fasting insulin (p < 0.05). In middle-school children who were overweight, there was a significant relationship between the power component of fitness and cardiovascular aerobic fitness (measured by VO(2)max). This more accessible and less intimidating field-based measure of power may prove useful in predicting changes in cardiovascular fitness. Thus, accurate assessment of childhood aerobic fitness may be achievable by measurement of power, possibly within the school environment at substantially less cost and effort than laboratory-based measurements.     

Ageing and isokinetic plantar flexion

Isokinetic torques (Cybex II) of the plantar flexors in 25 healthy men were compared at 5 angular velocities (30, 60, 90, 120 and 180 degrees X s-1). The purposes were to compare plantar flexion torques in young and old subjects, and to determine whether the expected decrease was significantly associated with age, physical activity, or aerobic fitness. Four groups were studied: young (21.7 +/- 2.0 years) and older (63.3 +/- 2.8 years), active and sedentary. Measurements of height, weight, % body fat, VO2max, and daily leisure energy expenditure (questionnaire) were determined for each subject. Statistical measures of analysis of variance were used to determine significant differences among groups; product moment correlation and stepwise regression analysis were used to describe the degree of association between the dependent variable of plantar flexion torque and the independent variables at each velocity. A decline in torque was observed as the isokinetic velocity of angular motion increased. Age alone was a significant determinant of plantar flexion torque, whereas at the slowest speed, when VO2max was used as an explanatory variable, age was not a significant determinant of torque. At 30 degrees X s-1 47% of the variance in torque was explained by VO2max while at 180 degrees X s-1 49% of the variance was explained by age.     

Physical fitness profile of Army ROTC cadets

One role of Army Reserved Officer's Training Corps (ROTC) programs is to physically prepare cadets for the demands of a military career. Cadets participate in physical training 3 days per week as part of their military science curriculum. Limited research has been conducted on the fitness level of ROTC cadets; therefore, the purpose of this study was to profile the physical fitness status of a cadre of ROTC cadets. Forty-three cadets (30 men and 13 women) performed Army Physical Fitness Test (APFT) assessments (2-mile run, 2-minute maximum push-ups and sit-ups) and clinical assessments of fitness (Bruce protocol Vo(2)max, underwater weighing, and 1 repetition maximum [1RM] bench press tests). Mean +/- standard deviations were calculated to provide the physical fitness profile for each parameter. Male cadets (21 +/- 2.2 years; height 177.4 +/- 6.6 cm; mass 79.2 +/- 9.4 kg) scored 49.6 +/- 6.1 ml.kg(-1).min(-1) for Vo(2)max, 14.8 +/- 4.2% fat, 86.5 +/- 24.9 kg 1RM bench press, 2-mile run of 13.97 +/- 1.4 minutes, 70.5 +/- 12.8 sit-ups, and 60.2 +/- 13.2 push-ups. Female cadets (20 +/- 2.4 years; height 165.1 +/- 8.0 cm; mass 63.5 +/- 10.0 kg) scored 40.8 +/- 3.9 ml.kg(-1).min(-1) for Vo(2) max, 23.9 +/- 3.8% fat, 35.3 +/- 8.2 kg 1RM bench press, 2-mile run of 17.0 +/- 1.6 minutes, 65.0 +/- 12.9 sit-ups, and 33.3 +/- 11.2 push-ups. The mean scores were above the 83rd percentile on all APFT items and average (percent fat) to above average (Vo(2)max and men's bench press scores) when compared with peer-age and sex-corrected norms. Only the women's bench press score was below average. With the exception of the women's bench press, these ROTC cadets possessed average to above average levels of fitness.     

Body fat and racial genetic admixture are associated with aerobic fitness levels in a multiethnic pediatric population

Aerobic fitness and adiposity are each independently associated with health outcomes among children, although the relationship between these two variables is unclear. Our objectives were to evaluate (i) the association of adiposity with aerobic fitness using objectively measured levels of percent body fat, compared to BMI as a percentile proxy for adiposity while controlling for genetic admixture, and (ii) the congruence of BMI categories with high and low body fat categories of objectively measured percent body fat. Participants were 232 African-American (AA), European-American (EA), and Hispanic-American (HA) children aged 7-12 years (Tanner stage <3). Aerobic fitness was measured via a submaximal indirect calorimetry treadmill test (VO(2-170)), and physical activity levels with accelerometry. Genetic admixture estimates were obtained using 140 genetic ancestry informative markers to estimate European, African, and Amerindian admixture. Fat mass was determined using dual-energy x-ray absorptiometry (DXA). Children were classified into a low body fat group (<25% in males, <30% in females) or a high body fat group based on their percent body fat; children were also categorized according to BMI percentile. Children in the low body fat group had significantly higher aerobic fitness (P < 0.05) regardless of BMI percentile classification. Higher African genetic admixture was associated with lower aerobic fitness (P < 0.05), while physical activity was positively associated with fitness (P < 0.01). In conclusion, aerobic fitness levels differ by percent body fat and genetic admixture irrespective of BMI classification, and such differences should be taken into account when evaluating outcomes of health interventions.     

Lymphocyte proliferation responses after exercise in men: fitness, intensity, and duration effects

This study investigated the effects of intensity and duration of exercise on lymphocyte proliferation as a measure of immunologic function in men of defined fitness. Three fitness groups--low [maximal O2 uptake (VO2max) = 44.9 +/- 1.5 ml O2.kg-1.min-1 and sedentary], moderate (VO2max = 55.2 +/- 1.6 ml O2.kg-1.min-1 and recreationally active), and high (VO2max = 63.3 +/- 1.8 ml O2.kg-1.min-1 and endurance trained)--and a mixed control group (VO2max = 52.4 +/- 2.3 ml O2.kg-1.min-1) participated in the study. Subjects completed four randomly ordered cycle ergometer rides: ride 1, 30 min at 65% VO2max; ride 2, 60 min at 30% VO2max; ride 3, 60 min at 75% VO2max; and ride 4, 120 min at 65% VO2max. Blood samples were obtained at various times before and after the exercise sessions. Lymphocyte responses to the T cell mitogen concanavalin A were determined at each sample time through the incorporation of radiolabeled thymidine [( 3H]TdR). Despite differences in resting levels of [3H]TdR uptake, a consistent depression in mitogenesis was present 2 h after an exercise bout in all fitness groups. The magnitude of the reduction in T cell mitogenesis was not affected by an increase in exercise duration. A trend toward greater reduction was present in the highly fit group when exercise intensity was increased. The reduction in lymphocyte proliferation to the concanavalin A mitogen after exercise was a short-term phenomenon with recovery to resting (preexercise) values 24 h after cessation of the work bout. These data suggest that single sessions of submaximal exercise transiently reduce lymphocyte function in men and that this effect occurs irrespective of subject fitness level.     

Effect of high-intensity interval training on cardiovascular function, VO2max, and muscular force

The purpose of this study was to examine the effects of short-term high-intensity interval training (HIIT) on cardiovascular function, cardiorespiratory fitness, and muscular force. Active, young (age and body fat = 25.3 ± 4.5 years and 14.3 ± 6.4%) men and women (N = 20) of a similar age, physical activity, and maximal oxygen uptake (VO2max) completed 6 sessions of HIIT consisting of repeated Wingate tests over a 2- to 3-week period. Subjects completed 4 Wingate tests on days 1 and 2, 5 on days 3 and 4, and 6 on days 5 and 6. A control group of 9 men and women (age and body fat = 22.8 ± 2.8 years and 15.2 ± 6.9%) completed all testing but did not perform HIIT. Changes in resting blood pressure (BP) and heart rate (HR), VO2max, body composition, oxygen (O2) pulse, peak, mean, and minimum power output, fatigue index, and voluntary force production of the knee flexors and extensors were examined pretraining and posttraining. Results showed significant (p < 0.05) improvements in VO2max, O2 pulse, and Wingate-derived power output with HIIT. The magnitude of improvement in VO2max was related to baseline VO2max (r = -0.44, p = 0.05) and fatigue index (r = 0.50, p < 0.05). No change (p > 0.05) in resting BP, HR, or force production was revealed. Data show that HIIT significantly enhanced VO2max and O2 pulse and power output in active men and women.     

The influence of training on physical and functional growth before, during and after puberty

In boys, the ages at which growth rates for body weight, height, VO2max, maximum O2 pulse and VImax reached their peaks were approximately the same (means and SD: 14.64 +/- 0.98, 14.67 +/- 0.99, 14.71 +/- 1.59, 14.38 +/- 1.36 and 14.64 +/- 1.42 years respectively). There was a positive relationship between the peak velocities of functional capacity indicators (VO2max 0.79 +/- 0.19 1.min-1.year-1, O2 pulse max 4.1 +/- 1.20 ml.year-1, VImax 27.3 +/- 7.15 l.min-1.year-1) and the peak growth velocity of weight and/or height (weight 9.1 +/- 1.92 kg.year-1, height 9.8 +/- 1.92 cm.year-1). A positive relationship between the age at peak velocity of VO2max and O2 pulse max with the age at peak velocity for body weight was also found (r = 0.524 and 0.400 respectively). No relationship was revealed between the age at peak velocity on the one hand and the peak velocities of body weight, height, VO2max, O2 pulse or VImax on the other. Moderate training did not influence acceleration in growth--the age at peak velocity and the peaks of the growth rate did not differ in groups with a different regime of exercise (higher - n = 8, medium - n = 9, lower - n = 12; the peak velocity of VO2max--means and SD--being 0.85 +/- 0.15, 0.76 +/- 0.22 and 0.78 +/- 0.17.min-1.year-1 respectively).     

The influence of cardiorespiratory fitness on the decrement in maximal aerobic power at high altitude

There are conflicting reports in the literature which imply that the decrement in maximal aerobic power experienced by a sea-level (SL) resident sojourning at high altitude (HA) is either smaller or larger for the more aerobically "fit" person. In the present study, data collected during several investigations conducted at an altitude of 4300 m were analyzed to determine if the level of aerobic fitness influenced the decrement in maximal oxygen uptake (VO2max) at HA. The VO2max of 51 male SL residents was measured at an altitude of 50 m and again at 4300 m. The subjects' ages, heights, and weights (mean +/- SE) were 22 +/- 1 yr, 177 +/- 7 cm and 78 +/- 2 kg, respectively. The subjects' VO2max ranged from 36 to 60 ml X kg -1 X min -1 (mean +/- SE = 48 +/- 1) and the individual values were normally distributed within this range. Likewise, the decrement in VO2max at HA was normally distributed from 3 ml X kg-1 X min-1 (9% VO2max at SL) to 29 ml X kg-1 X min-1 (54% VO2max at SL), and averaged 13 +/- 1 ml X kg-1 X min-1 (27 +/- 1% VO2max at SL). The linear correlation coefficient between aerobic fitness and the magnitude of the decrement in VO2max at HA expressed in absolute terms was r = 0.56, or expressed as % VO2max at SL was r = 0.30; both were statistically significant (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Body composition and physical performance during a National Collegiate Athletic Association Division I men's soccer season

The purpose of this study was to examine changes in body composition (BC) and physical performance tests (PT) resulting from a competitive season in soccer. Twenty-five male collegiate players (age = 19.9 +/- 1.3 years; height = 177.6 +/- 6.4 cm; body mass = 77.6 +/- 8.6 kg, and percentage body fat = 12.8 +/- 5.2%) were tested before (PRE) and after (POST) the 2003-2004 National Collegiate Athletic Association season. The following tests were performed: BC (anthropometric and dual energy x-ray absorptiometry measurements), vertical jump (VJ), 9.1-m (9 m) and 36.5-m (36 m) sprint, lower-body power (LP), total body power (TP), and cardiorespiratory endurance (VO(2)max). Training was divided into soccer-specific training: field warm-up drills, practices, games, and additional conditioning sessions. A daily, unplanned, nonlinear periodization model was used to assign session volume and intensity for strength sessions (total repetitions < or =96 and workload was > or =80% of 1 repetition maximum). For the entire team, body mass significantly increased by 1.5 +/- 0.4 kg from PRE to POST due to a significant increase in total lean tissue (0.9 +/- 0.2 kg). Regionally, lean tissue mass significantly increased in the legs (0.4 +/- 0.0 kg) and trunk (0.3 +/- 0.1 kg). Physical performance variables were very similar for the entire team at PRE and POST; VJ (cm) = 61.9 +/- 7.1 PRE vs. 63.3 +/- 8.0 POST, 9.1-m (s) = 1.7 +/- 0.1 PRE and POST, 36.5-m (s) = 5.0 +/- 0.2 PRE and POST, predicted VO(2)max (ml.kg.min(-1))= 59.8 +/- 3.3 PRE vs. 60.9 +/- 3.4 POST. The only significant improvements across the season were for TP (17.3%) and for LP (10.7%). In conclusion, soccer athletes who begin a season with a high level of fitness can maintain, and in some cases improve, body composition and physical performance from before to after a competitive season. A correct combination of soccer-specific practices and strength and conditioning programs can maintain and develop physical performance, allowing a soccer athlete to perform optimally throughout pre-, in-, and postseason play.