Youth activity versus youth fitness: let's redirect our efforts.
Explore the source record for details and available documents.
Adolescent↗
Biomedical subjects
P S Freedson
Publications and source records attributed to P S Freedson.
Physical activity among children and youth.
The positive influence of physical activity on chronic disease has been well established for the adult population. Much less is known about the relationship between physical inactivity and risk factors for coronary heart disease in children. It has not been clearly established how active children are, nor do we know the factors that determine physical activity patterns among youth. The purpose of this brief review is to describe different techniques used to assess physical activity that are consistent with the operational definition of physical activity. Descriptive information from the National Children and Youth Fitness Studies related to children's level of physical activity is provided which indicates that children are physically active. Nevertheless, it is suggested that the importance of regular physical activity should be emphasized to our youth to promote lifetime activity participation for long-term health and well-being.
Adolescent↗
Effect of internal work on the calculation of optimal pedaling rates.
The purpose of this study was to calculate optimal pedaling rates based upon external work (EW) rate and mechanical work (MW) rate criteria that respectively exclude and include the internal work (IW) rate of the lower limbs. Metabolic and kinematic data were collected as 12 males pedaled an ergometer at rates of 40, 60, 80, and 98 rpm while producing external power outputs of 49, 98, and 146 W. Energy expenditure (EE) was calculated from steady rate oxygen uptake and respiratory exchange ratio values. The IW rate was determined from digitized kinematic data by modeling the thigh, shank, and foot as a three-segment linked system and calculating their changes in potential, translational kinetic, and rotational kinetic energy. The EW rate was calculated from the observed pedaling rate and the ergometer resistance. The MW rate was defined as the sum of the EW rate and IW rate. At each level of external power output, the MW rate increased linearly with pedaling rate increments while the EE displayed a curvilinear relationship. Both gross efficiency (GE = EW rate/EE) and mechanical efficiency (ME = MW rate/EE) responded quadratically to pedaling rate treatments but a repeated measures ANOVA revealed significant differences in their beta 0, beta 1, and beta 2 regression coefficients. Optimal pedaling rates calculated from ME were consistently higher (82 to 101 rpm) than those determined from GE (35 to 57 rpm). The pedaling rates that optimized ME, but not GE, are similar to the rates reported to be biomechanically optimal and preferred by trained cyclists. This study demonstrates that the choice of a work rate criterion can alter the meaning and interpretation of metabolic data.
Adult↗
Estimation of VO2max: a comparative analysis of five exercise tests.
Thirty-eight female subjects (M +/ SD = 33 +/- 3.0 years) had VO2max measured on the cycle ergometer (M +/- SD = 37.3 +/- 6.4 ml.kg-1.min-1) and on the treadmill (M +/- SD = 41.3 +/- 6.6 ml.kg-1.min-1). VO2max was estimated for each subject from heart rate (HR) at submaximal workloads on the cycle ergometer using the Astrand-Rhyming nomogram (A/R) and the extrapolation method (XTP). VO2max was also estimated from three field tests: 1.5-mile run (RUN) (independent variable [IV] = time), mile walk (WALK) (IV = time, age, HR, gender, body weight), and the Queens College Step Test (ST) (IV = HR during 5-20 s recovery). Repeated measure ANOVA revealed significant mean differences between the criterion cycle ergometer VO2max versus A/R and XTP (20 and 12% overestimation). The WALK, RUN, and ST VO2max values were not significantly different from the criterion treadmill VO2max. The correlation between criterion VO2max estimated from the WALK and RUN were r = .73 (SEE = 4.57 ml,kg-1.min-1) and r = .79 (SEE = 4.13 ml.kg-1.min-1), respectively. The ST, A/R, and XTP had higher SEEs (13-13.5% of the mean) and lower r s (r = .55 to r = .66). These results suggest both the WALK and RUN tests are satisfactory predictors of VO2max in 30 to 39-year-old females.
Adult↗
Familial aggregation in physical activity.
The purposes of this study were to (a) examine the stability and consistency of the Caltrac accelerometer (Hemokinetics, Madison, WI) and an activity record to assess physical activity in children and adults (Experiment 1), and (b) to determine if there is a relationship between parents and their children in physical activity level (Experiment 2). Thirty 5-9-year-old children and their biological parents wore Caltrac accelerometers for three consecutive days (including one weekend day). At the same time, parents completed a Caltrac Activity Record (CAL REC) for themselves and their child. Dependent variables were counts per day for the Caltrac and minutes of light activity and activity for the CAL REC. Between-day correlations for the Caltrac ranged from r = .73 to .87 for the parents (p less than .001) and from r = .38 (p less than .04) to .79 (p less than .001) for the children. An analysis of variance with repeated measures indicated no significant differences for the Caltrac between days for parents and children. Between-day correlations for CAL REC ranged from r = .67 to .91 (p less than .05) for parents and r = .36 to .72 (p less than .05) for children, and there were no significant differences between days. In Experiment 2, chi 2 analyses were used to examine familial resemblance in physical activity. Using the Caltrac, familial resemblance occurred in 67% (father and child) and 73% (mother and child) of the families. Using the CAL REC, familial aggregation was present in 70% (father and child) and 66% (mother and child) of the families.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Electronic motion sensors and heart rate as measures of physical activity in children.
Explore the source record for details and available documents.
Adolescent↗
Effects of coenzyme Q10 supplementation on exercise performance, VO2max, and lipid peroxidation in trained cyclists.
The effects of dietary supplementation with Coenzyme Q10 (CoQ10), a reputed performance enhancer and antioxidant, on physiological and biochemical parameters were examined. Ten male bicycle racers performed graded cycle ergometry both before and after being given 100 mg per day CoQ10 or placebo for 8 weeks. Analysis of variance showed a significant difference between groups for postsupplementation serum CoQ10. Although both groups demonstrated training related improvements in all physiological parameters over the course of the study, there were no significant differences between the two groups (p > .05). Both groups showed a 21% increase in serum MDA (an index of lipid peroxidation) after the presupplementation exercise test. After 8 weeks this increase was only 5%, and again was identical for both groups. Supplementation with CoQ10 has no measurable effect on cycling performance, VO2max, submaximal physiological parameters, or lipid peroxidation. However, chronic intense training seems to result in marked attenuation of exercise-induced lipid peroxidation.
Adult↗
Bias in estimating caloric expenditure from physical activity in children. Implications for epidemiological studies.
Explore the source record for details and available documents.
Age Factors↗
Walking for exercise testing and training.
Explore the source record for details and available documents.
Adult↗
Anthropometric measurements of adolescent and professional classical ballet dancers.
This study examined anthropometric measures of 83 female adolescent students attending the Boston Ballet summer program and 15 professional dancers from the Boston Ballet Company. Thirty-one were in the least advanced level (group A), 38 were in the moderately advanced level (group B) and 14 were in the most advanced level (group C). The adolescent dancers devoted between 17 and 23 hours per week in dance training, while professional dancers spent 39.2 hours per week in class and rehearsals. Compared to normative data, the dancers tended to be tall and slim. The skinfold, diameter, and circumference measurements were found to be very similar among groups A, B and C, and between group C and the company members. The somatograms demonstrated that the ballet dancers had relatively smaller upper arms and larger calves and ankles compared with the reference female. The data from this study suggest that the body type characteristics associated with professional classical ballet dancers are already apparent in the pre-professional adolescent dancers.
Adolescent↗
Walking for health and fitness.
Recent studies have linked regular physical activity with reduced likelihood of developing coronary heart disease. Even low- and moderate-intensity exercise such as walking, when carried out consistently, is associated with important cardiovascular health benefits. Walking has also been shown to reduce anxiety and tension and aid in weight loss. Regular walking may help improve cholesterol profile, help control hypertension, and slow the process of osteoporosis. Recent physiological studies have demonstrated that brisk walking provides strenuous enough exercise for cardiovascular training in most adults. A recently developed submaximal 1-mile walk test provides a simple and accurate means for estimating aerobic capacity and guiding exercise prescription. These new insights and tools will assist the clinician in the prescription of safe and effective walking programs.
Coronary Disease↗
Effects of shoe type on cardiorespiratory responses and rearfoot motion during treadmill running.
Running kinematics and physiological responses to high intensity submaximal treadmill running in training shoes and racing flats were evaluated. Eight women (mean age = 21.9 yr) completed a peak VO2 test on the treadmill (mean peak VO2 = 49.2 ml.kg-1.min-1). In two subsequent testing sessions, subjects completed 15-min runs at a speed corresponding to 90% of peak VO2 (range = 9.9-13.4 km.hr-1) while wearing training shoes and racing flats (balanced order assignment). No significant time effect or time by shoe condition interaction was observed for the rearfoot motion variables. Maximum rearfoot angle and total rearfoot motion averaged 42% and 13.9% higher, respectively, for the racing flat (P less than 0.05). There were significant increases over time for VO2, VE, HR, and RPE, indicating an increase in cardiorespiratory response and the perception of effort over the course of the 15-min run. Thus, metabolic and perceptual indications of fatigue at the end of the run emerged but were not accompanied by rearfoot motion changes in either running shoe. These results indicate that rearfoot motion is a function of shoe design and did not change during 15 min of high intensity running.
Adult↗
Estimation of VO2max from a one-mile track walk, gender, age, and body weight.
The purpose of this investigation was to explore an alternative field test to estimate maximal oxygen consumption (VO2max) using a one-mile walk test. VO2max was determined in 343 healthy adult (males = 165, females = 178) subjects 30 to 69 yr using a treadmill protocol (mean +/- SD: VO2max = 37.0 +/- 10.7 ml X kg-1 X min-1). Each subject performed a minimum of two, one-mile track walks as fast as possible. The two fastest walks (T1, T2) with elapsed times within 30 s were used for subsequent analyses. Heart rates were monitored continuously and recorded every one-quarter mile. Multiple regression analysis (best sub-sets) to estimate VO2max (l X min-1) yielded the following predictor variables: track walk-1 time (T1); fourth quarter heart rate for track walk-1 (HR 1-4); age (yr); weight (lb); and sex (1 = male, 0 = female). The best equation (N = 174) was: VO2max = 6.9652 + (0.0091*WT) - (0.0257*AGE) + (0.5955*SEX) - (0.2240*T1) - (0.0115*HR1-4); r = 0.93, SEE = 0.325 l X min-1. Comparing observed and estimated VO2max values in a cross-validation group (N = 169) resulted in r = 0.92, SEE = 0.355 l X min-1. Generalized and sex-specific equations to estimate VO2max (ml X kg-1 X min-1) were also generated. The accuracy of estimation as expressed by SEE was similar among the equations. The results indicate that this one-mile walk test protocol provides a valid sub-maximum assessment for VO2max estimation.
Adult↗
Physical training programs for public safety personnel.
The nature of public safety jobs often reflects sudden strenuous exertion at a moment's notice. In the 1970s, police and fire departments became acutely aware of high numbers of on-the-job injuries and illnesses related to coronary heart disease. Disability payments for premature cardiovascular problems were being linked to cardiovascular risk factors accrued while on the job. This prompted public safety departments to initiate fitness programs for their employees. The fitness level of public safety personnel is not high. Job-related benefits have been linked to consistent physical training; high aerobic capacity, high muscular strength and endurance, above-average lean body weight, and minimal body fat are necessary for efficient job performance. In light of the physical benefits gained through regular exercise, pioneer departments began exercise programs for their personnel. These included the fire departments in Lawrence, Kansas, Alexandria, Virginia and Los Angeles, and the Dallas police department. Mealey documents psychologic improvements with exercise. Pioneer fitness programs such as that of the Los Angeles fire department have noted evidence of risk-factor reduction following institution of a mandatory program. The Alexandria department has instituted mandatory entrance requirements for their recruits, such as a no-smoking policy while on the job and mandatory exercise participation. Many community departments are not able to justify the institution of fitness programs. They may cite cost, lack of space, or lack of administrative support for the inability to initiate these programs. Legal and union ramifications may also deter the effort of program implementation. Considerations when implementing programs should involve cost of equipment, space, employee input, and determination of mandatory versus voluntary status. Preliminary medical screening and fitness evaluations should reliably evaluate an employee's physical ability to perform job-related tasks. The tests should be performed on a regular basis during employment. It is important, therefore, to convey the benefits of exercise to administrators. Frequent exercise testing should record progress of participants during exercise training and goals should be constantly updated. Pioneer programs should be used as models to follow when implementing a public safety physical training program. However, individual departments should evaluate the needs of their own personnel with respect to equipment, exercise schedule and type, and place of training.(ABSTRACT TRUNCATED AT 400 WORDS)
Accidents, Occupational↗
Exercise intensity and erythrocyte 2,3-diphosphoglycerate concentration.
The present study examines the acute effects of two different exercise intensities on erythrocyte 2,3-diphosphoglycerate (2,3-DPG) concentration. Thirty-one females (X +/- SD age = 23.7 +/- 3.37 yr; VO2max = 44.3 +/- 5.40 ml X kg-1 X min-1) completed 2 separate 15-min constant load cycling tests at exercise intensities representing 35 and 75% of VO2max. Venous blood was obtained pre-exercise (PRE), immediately post-exercise (POST), 15 min post-exercise (POST15), and 30 min post-exercise (POST30) to determine lactic acid, 2,3-DPG, and hemoglobin concentrations and hematocrit. Significant increases (P less than 0.01) in lactic acid concentration (1.1 +/- 0.14 at PRE to 6.2 +/- 0.48 m X mol-1 X l-1 at POST), 2,3-DPG concentration (1.9 +/- 0.06 at PRE to 2.1 +/- 0.06 mumol X ml-1 at POST), and 2,3-DPG corrected for plasma volume shift (PVC 2,3-DPG) (1.9 +/- 0.06 at PRE to 2.4 +/- 0.07 mumol X ml-1 at POST15) were observed only following the 75% submaximal exercise. At POST30 (75% VO2max) PVC 2,3-DPG and lactic acid remained 5.3 and 97% (P less than 0.05) above baseline, respectively. An exercise intensity effect was observed only in lactic acid response (P less than 0.05) but not in 2,3-DPG (mumol X ml-1 and mumol X g-1 hemoglobin or PVC 2,3-DPG. A significant time-intensity interaction (P less than 0.05) for PVC 2,3-DPG suggests that PVC 2,3-DPG response over time was different between the two exercise intensity levels, with the 75% intensity eliciting a greater increase in PVC 2,3-DPG.(ABSTRACT TRUNCATED AT 250 WORDS)
2,3-Diphosphoglycerate↗
Evaluation of acute cardiorespiratory responses to hydraulic resistance exercise.
Accurate evaluation of the acute responses to resistance exercise training depends on the stability of the criterion measures. This is particularly true for maximal effort exercise where continuous "all-out" effort for each repetition is encouraged. The present study evaluated reliability of repetition number (repN), respiratory gas parameters (VO2, VCO2, VE), and heart rate (HR) for shoulder (SE), chest (CE), and leg (LE) exercise performed maximally on a single-unit, 3-station hydraulic resistance exercise machine (Hydra-Fitness, Belton, TX). On 2 separate days, 20 college men completed three 20-s bouts of SE, CE, and LE with a 20-s rest between bouts and 5 min between exercise modes. There were no significant differences between bouts or test days for repN, gas measures, or HR. Subjects performed 17, 19, and 21 reps during SE, LE, and CE. VO2 was 1.7 l . min-1 (24.3 ml . kg-1 . min-1) for SE, 1.87 l . min-1 (25.5 ml . kg-1 . min-1) for CE, and 2.1 l . min-1 (28.6 ml . kg-1 . min-1) for LE. These values, averaged, represented 52.8% of the max VO2 determined on a continuous cycle ergometer test. The corresponding HR's during hydraulic exercise averaged 84.6% of HR max. Test-retest reliability coefficients ranged from r = .67 to .87 for repN, r = .41 to .83 for gas measures, and r = .72 to .89 for HR.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Isokinetic torque levels for high school football players.
One hundred fifteen high school football players were screened isokinetically for the knee extensor and flexor torque generating capabilities and muscle imbalances. Each player was tested on a Cybex II at speeds of 30 degrees/sec and 180 degrees/sec. The subjects were stratified by age (15, 16, 17) and by position (linemen vs receivers and backs). Significant (p less than 0.05) torque differences were observed at both the slow and fast speeds for the knee extensors and flexors across the 3 age groups. However, the flexion to extension ratios did not differ significantly. On the other hand, when considering the positions, flexor torque and flexion to extension ratio at the slow speed were greater (p less than 0.05) for the linemen than the receivers and backs. Partial correlation analyses showed that body weight had the greatest effect on the knee torque values. It was concluded that basic torque measures differed with age and by position in the sport of football. Also, speed of movement altered the force generating capabilities of the muscle and resultant ratios.
Adolescent↗