Physical fitness measures among children and adolescents: are they all necessary?

AIM

The aim of this paper was to investigate the relationship among health and skill-related physical fitness variables, and with anthropometric measures in a sample of children and adolescents.

METHODS

A cross-sectional study was conducted with 526 Brazilian students aged 7-15 years. Physical fitness abilities/skills were assessed through a battery of eight tests: sit-and-reach, standing long jump, 1-minute curl-up, modified pull-up, medicine-ball throw, 9-minute run, 20-meter run and 4 meter shuttle-run. Anthropometric measures considered were weight, height, body mass index (BMI) and wingspan. Analyses included descriptive statistics, Pearson correlations, multiple linear regression and principal component analysis.

RESULTS

Anthropometric measures were directly associated between each other. Weight and BMI were negatively associated with the performance in all physical tests requiring propulsion or lifting of the body mass. Direct associations between tests persisted after adjustments for sex, age, type of school and geographic region of school.

CONCLUSION

Results from the principal component analysis evidenced that all physical abilities/motor skills, except flexibility, are strongly associated with each other, suggesting that one test can reflect the overall fitness among youth. Although it is unclear from these analyses which test would be the single choice indicator, previous work on the health impact of cardiorespiratory fitness would suggest that.

Health-related quality of life, BMI and physical activity among US adults (⩾18 years): National Physical Activity and Weight Loss Survey, 2002

OBJECTIVE

To examine the association between health-related quality of life (HRQOL) and physical activity (PA).

METHODS

Cross-sectional data were obtained via a national telephone survey from 9173 respondents (30.9% response rate; 51.4% cooperation rate). Four indicators of HRQOL were measured: self-rated health, physically unhealthy days, mentally unhealthy days and activity limitation days. Prevalence estimates were calculated by body mass index (BMI) category and PA level. Logistic regression evaluated BMI as an effect modifier of the relationship between HRQOL and PA.

RESULTS

Inactive adults reported more fair to poor HRQOL than active adults, regardless of BMI category (P<0.001). BMI did not modify the association between PA and any of the four HRQOL indicators.

CONCLUSION

Prevalence of low HRQOL is inversely related to PA participation, and the relationship is not altered by BMI status. Regardless of their weight status, adults should be encouraged to engage in PA.

Interactive effects of tunnel dilation on the mechanical properties of hamstring grafts fixed in the tibia with interference screws

The effect of dilation of the tibial tunnel on the strength of hamstring graft fixation using interference screws was evaluated. In all, 28 RCI screws were tested in male human tibia-hamstring constructs with tibial tunnels reamed or dilated to the respective size of the graft diameter. Dilation of the tibial tunnel failed to significantly enhance hamstring fixation. Grafts secured in dilated tunnels displayed an 11% greater resistance to the initiation of graft slippage (174+/-112 N) compared to their undilated controls (156+/-77 N, P=0.63). Dilation of the tibial tunnel increased the failure load by an average of 4%, independent of screw diameter (dilated specimens: 360+/-120 N, controls: 345+/-88 N, P=0.74). Biomechanical research on the effect of tibial tunnel dilation in hamstring fixation has not provided satisfactory evidence as to the benefits of this additional surgical step during anterior cruciate ligament (ACL) reconstruction.

Biomechanical evaluation of the origin of the long head of the biceps tendon

PURPOSE

Lesions of the superior glenoid labrum extending anterior and posterior (SLAP) have recently been recognized as important sources of shoulder pain and dysfunction. Among the 4 described types of SLAP lesions, the type II SLAP involves detachment of the superior labrum from the bony glenoid and destabilization of the origin of the long head of the biceps tendon (LHBT). The purpose of this cadaveric biomechanical study was to evaluate the relative contribution regarding linear stiffness and displacement under load of the 2 origins of the LHBT: the superior glenoid labrum and the supraglenoid tubercle (the biceps anchor).

TYPE OF STUDY

Cadaveric biomechanical study.

METHODS

Seven pairs of fresh-frozen cadaveric shoulders were dissected free of all soft tissue except for the glenoid labrum and LHBT. Tension from 0 to 55 N was applied to the LHBT while keeping the tendon perpendicular to the face of the glenoid. Each specimen was tested for linear stiffness and biceps tendon displacement in the intact state, after releasing 1 of the LHBT origins, and after releasing the remaining origin.

RESULTS

The average stiffness of the LHBT origin was 103 N/mm. Sectioning the anchor alone resulted in a 52% reduction in linear stiffness, whereas only detaching the superior glenoid labrum from the 10 o'clock to the 2 o'clock position resulted in a 15% reduction in linear stiffness. Maximum displacement of the biceps tendon origin in the intact state at the 55 N load averaged 0.99 mm. With a minimum load applied, displacement changed less than 1 mm unless both origins were released.

CONCLUSIONS

The results indicate that the biceps anchor is the primary restraint of the LHBT and that the superior labrum is a secondary restraint in regard to linear stiffness. However, disruption of both restraints is required to produce the laxity typically seen in a type II SLAP lesion.

Pelvic fracture among polytrauma decedents. Trauma-based mortality with pelvic fracture--a case series of 74 patients

Pelvic fractures (PF) sustained from accidents are commonly believed to be a major cause of mortality in polytraumatized patients. The purpose of this paper is to determine whether PF are usually the primary cause or a contributing cause of mortality in these patients. A 10-year retrospective review was performed of all polytrauma patients with PF who were admitted to, and died, at a large, level-I trauma center. The pelvic injury was graded according to Schatzker and Tile into stable (type A), partially stable (type B), and unstable (type C). The injury severity score (ISS), which incorporates associated injuries and their potential impact on mortality, was calculated for all patients. For each patient, a separate subjective designation of the probable cause of death was determined. We identified 74 decedents with PF following deceleration trauma. The pelvic fractures were classified as 12 type A (16%), 36 type B (49%), and 26 type C (35%). The mean ISS was extremely high, 40.6 +/- 1.4 (range 18-75), more than four times the score for simply a severe PF. The ISS was also not significantly different among the three pelvic fracture groups (P = 0.613). The records subjectively identified PF as the precipitating cause of death in only 13% of the patients. In this study, patients who died with PF had an ISS that implicated at least one or two additional major visceral injuries. These data do not support the hypothesis that PF, regardless of its complexity, is the usual primary cause or the major precipitating event of death in the polytraumatized patient. In these patients, mortality appears to be a function of the associated injuries based on the ISS calculation.

Field evaluation of energy expenditure from continuous and intermittent walking in women

RATIONALE

Recent physical activity recommendations suggest that comparable amounts of prescribed physical activity, done as a single continuous bout or as a set of intermittent bouts, will produce equal amounts of energy expenditure (EE) during the prescribed activity as well as throughout the day.

HYPOTHESES

In a field setting, we tested two hypotheses: (1) continuous and intermittent walking conditions will result in significantly greater total daily EE than a control condition, and (2) continuous and intermittent walking conditions will result in similar total daily

METHODS

Thirty women (mean age [yr] = 43.7+/-5.8; mean body mass index [kg x m(-2)]= 24.7+/-4.0) participated in a repeated-measures design so that each woman participated in three walking conditions on successive days of the week: a single 30-min brisk walk (continuous): three 10-min brisk walks (intermittent); and no activity (control). Throughout the study protocol, women wore a TRITRAC-R3D accelerometer programmed to estimate EE in 2-min intervals.

RESULTS

Mean total EE estimates (kcal) for the three walking conditions were as follows: continuous: 2181+/-308; intermittent: 2121+/-305; and control: 1948+/-270. A repeated-measures analysis of variance omnibus test indicated that EE differed significantly by experimental condition [F(2,58) = 40.2, P < 0.001). To test the first hypothesis, contrasts were examined revealing that EE in the continuous and intermittent conditions was significantly greater than EE in the control condition [F(1,29) = 58.2, P < 0.001]. To test the second hypothesis, contrasts revealed that EE in the continuous condition was significantly greater than EE in the intermittent condition [F(1,29) = 7.0, P = 0.013].

CONCLUSION

For the purposes of total EE, selecting a continuous mode of walking may offer additional benefit over an intermittent mode, given the same total prescribed duration.

Work ability, physical activity, and cardiorespiratory fitness: 2-year results from Project Active

An adequate level of physical activity may maintain or promote work ability in aging workers. Project Active is a randomized trial comparing a Lifestyle physical activity program with a Structured exercise program in sedentary but healthy adults aged 35 to 60 years. Subjects in both groups received 6 months of intensive intervention followed by 18 months of active follow-up. The total number of subjects was 235, from which 80 subjects participated in the work ability assessment. Primary outcome measures were energy expenditure (kcal.kg-1.day-1), cardiorespiratory fitness (peak oxygen uptake in ml.min-1.kg-1), and the Work Ability Index. At 6 months, daily energy expenditure had increased significantly over baseline (mean +/- SD, from 33.0 +/- 0.9 to 34.4 +/- 1.8 kcal.kg-1.day-1) and was maintained over baseline at 24 months (34.0 +/- 2.5 kcal.kg-1.day-1). The significant increase in energy expenditure was observed particularly in moderate levels of activity. The average percentage of body fat was significantly higher at baseline compared with 6 months and 24 months. Peak oxygen uptake increased from baseline significantly during the first 6 months (from 29.6 +/- 5.7 to 30.6 +/- 6.3 ml.min-1.kg-1) and decreased to the baseline level (29.1 +/- 5.5 ml.min-1.kg-1) at 24 months. At baseline, the average Work Ability Index was 44.2 +/- 4.0, and it remained unchanged at 6 months (44.4 +/- 3.9) and at 24 months (44.2 +/- 3.1). In conclusion, a 2-year physical activity intervention increased daily energy expenditure, reduced body fat, and maintained peak oxygen uptake in healthy, middle-aged, sedentary subjects. The average Work Ability Index score at baseline was excellent and did not change during the 2-year physical activity interventions.

Reliability of the Lichtman classification of Kienböck's disease

The purpose of this study was to establish the interobserver reliability and intraobserver reproducibility of the staging of Kienböck's disease according to Lichtman's classification. Posteroanterior and lateral wrist radiographs of 64 patients with a diagnosis of Kienböck's disease and 10 control subjects were reviewed independently by 4 observers on 2 separate occasions. The reviewers included 3 hand fellowship-trained surgeons and 1 orthopedist who was not fellowship-trained in hand surgery. A stage was assigned to each set of radiographs according to the Lichtman classification. Paired comparisons for reliability among the 4 observers showed an average absolute percentage agreement of 74% and an average paired weighted kappa coefficient of 0.71. Furthermore, all the controls were correctly classified as stage I, which is in accordance with the Lichtman system. With regard to reproducibility, observers duplicated their initial readings 79% of the time with an average weighted kappa coefficient of 0.77. These results indicate substantial reliability and reproducibility of the Lichtman classification for Kienböck's disease.

Effect of quadriceps contraction on tangential patellar radiography

This study examined whether the addition of quadriceps contraction to standard Merchant views provides additional useful information in the evaluation of patients with extensor mechanism malalignment. Fifteen patients (23 knees) with anterior knee pain due to lateral patellar compression syndrome and 22 control patients (44 knees) underwent standard Merchant views with the quadriceps relaxed and with an isometric isotonic contraction. Congruence and lateral patellar angles were measured for all groups. Although the congruence angle differed significantly between the control and symptomatic groups with the quadriceps contracted (P< or = .001), this difference also was seen without quadriceps contraction. There was also no significant difference within each group on addition of quadriceps contraction. No significant difference existed between the two groups for lateral patellar angle with quadriceps contraction. The addition of a controlled isometric quadriceps contraction did not add to the diagnostic yield of the standard Merchant view in terms of a predictable change in measured radiographic parameters.

Physical training as a substance abuse prevention intervention for youth

Program evaluation data from school and community applications of a physical fitness drug prevention program is presented. A train-the-trainer methodology was applied to install the program in twenty-two settings within the state of Illinois. The physical training program consisted of exercise and educational modules delivered over a twelve-week time period that focused on learning values and life skills through exercise. Complete pre-post data were obtained on 329 participating youth at six school and community based sites. Significant increases were demonstrated in physical activity and physical fitness (cardiovascular endurance, strength, and flexibility). Youth self-report data indicated significant decreases in risk factors such as low self-concept, poor school attendance, anxiety, depression, and number of friends who use alcohol and drugs. There were significant reductions in the percentage of youth who used cigarettes, smokeless tobacco, and alcohol. It was concluded that a strong relationship was demonstrated for increased fitness leading to lowered risk factors and usage patterns. Likewise, the train-the-trainer model was shown to be an effective installation approach to expand fitness programming within prevention settings.

Cyclic pull-out strength of hamstring tendon graft fixation with soft tissue interference screws. Influence of screw length

Blunt-threaded interference screws used for fixation of hamstring tendons in anterior cruciate ligament reconstructions provide aperture fixation and may provide a biomechanically more stable graft than a graft fixed further from the articular surface. It is unknown if soft tissue fixation strength using interference screws is affected by screw length. We compared the cyclic and time-zero pull-out forces of 7 x 25 mm and 7 x 40 mm blunt-threaded metal interference screws for hamstring graft tibial fixation in eight paired human cadaveric specimens. A four-stranded autologous hamstring tendon graft was secured by a blunt-threaded interference screw into a proximal tibial tunnel with a diameter corresponding to the graft width. Eight grafts were secured with a 25-mm length screw while the other eight paired grafts were secured with a 40-mm length screw. During cyclic testing, slippage of the graft occurred as the force of pull became greater with each cycle until the graft-screw complex ultimately failed. All grafts failed at the fixation site, with the tendon being pulled past the screw. There were no measurable differences in the mean cyclic failure strength, pull-out strength, or stiffness between the two sizes of screws. Although use of the longer screw would make removal technically easier should revision surgery be necessary, it did not provide stronger fixation strength than the shorter, standard screw as had been postulated.

Long-term functional and radiographic follow-up of surgically treated isthmic spondylolisthesis

We studied patients treated surgically for isthmic spondylolisthesis since 1968, with special emphasis on a detailed functional assessment. We followed up 22 patients for an average of 15 years, with a mean age at time of surgery of 18 years. All patients underwent a thorough physical examination and were evaluated with radiographs at baseline and at follow-up. The functional status of patients at the time of follow-up was assessed with 2 self-report pain and function instruments. All surgical procedures included spinal fusion, 12 of which included internal fixation by using Harrington distraction rods with sacral bars. At final follow-up, there was no statistically significant difference in mean slip percentage or mean slip angle compared with baseline radiographs. Functional evaluation was compared with a control group consisting of 52 patients. We conclude that the long-term radiographic and functional outcome is excellent for patients treated surgically for isthmic spondylolisthesis.

Detecting bouts of physical activity in a field setting

The purposes of this study were to assess the TRITRAC and CSA for: (a) interaccelerometer agreement; (b) agreement in detecting patterns of moderate-intensity physical activity; and (c) agreement in detecting walking patterns recorded in a diary. Thirty-one women wore both the TRITRAC and CSA accelerometers for three consecutive days. Interaccelerometer agreement (measured with generalizability coefficients) ranged from .88 to .99. In total, 71.3% of the accelerometers' patterns agreed in length, with CSA patterns being on average significantly longer. Interaccelerometer agreement in detecting patterns of brisk walking, as recorded in a diary, was comparable (69.4%). Interaccelerometer discrepancies may be related in part to the threshold employed by each instrument for classifying moderate intensity patterns.

Assessing physical activity among minority women: focus group results

Focus group findings indicate a need to develop physical activity surveys that are more relevant for women, that include well-defined, inoffensive terminology, and that improve recall of unstructured and intermittent physical activities.

Physical fitness and clustering of risk factors associated with the metabolic syndrome

PURPOSE

The purposes of this study were to 1) assess the prevalence of clustering of metabolic markers of the MS in a defined population and 2) determine the association between CRF and such clustering in a large group of adult men (N = 15,537) and women (N = 3,899).

METHODS

Metabolic markers of the MS included systolic blood pressure (BP) > or = 140 mm Hg, serum triglycerides > or = 150 mg x dL(-1), fasting blood glucose > or = 110 mg x dL(-1), and elevated central adiposity (waist circumference > 100 cm). Cardiorespiratory fitness was defined as total time on a maximal treadmill exercise test. The cohort was grouped by the number of metabolic abnormalities and level of CRF. Associations between CRF and the number of metabolic abnormalities were assessed using proportional odds logit models.

RESULTS

Among men, the age-adjusted cumulative odds ratio for abnormal markers of the MS was 3.0 (95% C.I. 2.7-3.4; P < 0.001) for the least-fit men when compared with moderately-fit ones, and 10.1 (95% C.I. 9.1-11.2; P < 0.001) when compared with the most-fit men. Among women, the age-adjusted cumulative odds ratio was 2.7 (95% C.I. 2.1-3.5; P < 0.001) for the least-fit women when compared with moderately-fit ones, and 4.9 (95% C.I. 3.8-6.3; P < 0.001) when compared with the most-fit women.

CONCLUSIONS

These cross-sectional results suggest that low CRF is associated with an increased clustering of the metabolic abnormalities associated with the MS in both adult men and women and support the need for future prospective analyses.

Comparison of lifestyle and structured interventions to increase physical activity and cardiorespiratory fitness: a randomized trial

CONTEXT

Even though the strong association between physical inactivity and ill health is well documented, 60% of the population is inadequately active or completely inactive. Traditional methods of prescribing exercise have not proven effective for increasing and maintaining a program of regular physical activity.

OBJECTIVE

To compare the 24-month intervention effects of a lifestyle physical activity program with traditional structured exercise on improving physical activity, cardiorespiratory fitness, and cardiovascular disease risk factors.

DESIGN

Randomized clinical trial conducted from August 1, 1993, through July 31, 1997.

PARTICIPANTS

Sedentary men (n = 116) and women (n = 119) with self-reported physical activity of less than 36 and 34 kcal/kg per day, respectively.

INTERVENTIONS

Six months of intensive and 18 months of maintenance intervention on either a lifestyle physical activity or a traditional structured exercise program.

MAIN OUTCOME MEASURES

Primary outcomes were physical activity assessed by the 7-Day Physical Activity Recall and peak oxygen consumption (VO2peak) by a maximal exercise treadmill test. Secondary outcomes were plasma lipid and lipoprotein cholesterol concentrations, blood pressure, and body composition. All measures were obtained at baseline and at 6 and 24 months.

RESULTS

Both the lifestyle and structured activity groups had significant and comparable improvements in physical activity and cardiorespiratory fitness from baseline to 24 months. Adjusted mean changes (95% confidence intervals [CIs]) were 0.84 (95% CI, 0.42-1.25 kcal/kg per day; P<.001) and 0.69 (95% CI, 0.25-1.12 kcal/kg day; P = .002) for activity, and 0.77 (95% CI, 0.18-1.36 mL/kg per minute; P = .01) and 1.34 (95% CI, 0.72-1.96 mL/kg per minute; P<.001) for VO2peak for the lifestyle and structured activity groups, respectively. There were significant and comparable reductions in systolic blood pressure (-3.63 [95% CI, -5.54 to -1.72 mm Hg; P<.001] and -3.26 [95% CI, -5.26 to -1.25 mm Hg; P = .002]) and diastolic blood pressure (-5.38 [95% CI, -6.90 to -3.86 mm Hg; P<.001] and -5.14 [95% CI, -6.73 to -3.54 mm Hg; P<.001) for the lifestyle and structured activity groups, respectively. Neither group significantly changed their weight (-0.05 [95% CI, -1.05 to 0.96 kg; P = .93] and 0.69 [95% CI, -0.37 to 1.74 kg; P = .20]), but each group significantly reduced their percentage of body fat (-2.39% [95% CI, -2.92% to -1.85%; P<.001] and -1.85% [95% CI, -2.41 % to -1.28%; P<.001]) in the lifestyle and structured activity groups, respectively.

CONCLUSIONS

In previously sedentary healthy adults, a lifestyle physical activity intervention is as effective as a structured exercise program in improving physical activity, cardiorespiratory fitness, and blood pressure.

Physical activity patterns associated with cardiorespiratory fitness and reduced mortality: the Aerobics Center Longitudinal Study

OBJECTIVES

This study examined cross sectionally the physical activity patterns associated with low, moderate, and high levels of cardiorespiratory fitness.

METHODS

Physical activity was assessed by questionnaire in a clinic population of 13,444 men and 3972 women 20 to 87 years of age. Estimated energy expenditure (kcal.wk-1) and volume (min.wk-1) of reported activities were calculated among individuals at low, moderate, and high fitness levels (assessed by maximal exercise tests).

RESULTS

Average leisure time energy expenditures of 525 to 1650 kcal.wk-1 for men and 420 to 1260 kcal.wk-1 for women were associated with moderate to high levels of fitness. These levels of energy expenditure can be achieved with a brisk walk of approximately 30 minutes on most days of the week. In fact, men in the moderate and high fitness categories walked between 130 and 138 min.wk-1, and women in these categories walked between 148 and 167 min.wk-1.

CONCLUSIONS

Most individuals should be able to achieve these physical activity goals and thus attain a cardiorespiratory fitness level sufficient to result in substantial health benefits.

Physical fitness, physical activity, and functional limitation in adults aged 40 and older

PURPOSE

A cohort of middle-aged and older men and women were followed for an average of 5.5 yr to examine the association between physical fitness, physical activity, and the prevalence of functional limitation.

METHODS

The participants received medical assessments between 1980 and 1988 and responded to a mail-back survey regarding functional status in 1990.

RESULTS

Among 3495 men and 1175 women over 40 yr of age at baseline, 350 (7.5%) reported at least one functional limitation in daily or household activities at follow-up. The prevalence of functional limitation was higher among women than men. Physically fit and physically active participants reported less functional limitation than unfit or sedentary participants. After controlling for age and other risk factors, the prevalence of functional limitation was lower for both moderately fit (odds ratio = 0.4, 95% CI = 0.2-0.6) and high fit men (odds ratio = 0.3, 95% CI = 0.2-0.4), compared with low fit men. Corresponding figures for women were 0.5 (0.3-0.7) and 0.3 (0.2-0.5) for moderately fit and high fit women. The association between physical activity and functional limitation was similar to the data for physical fitness.

CONCLUSIONS

These data support a protective effect of physical fitness and physical activity on functional limitation among older adults and extend this protective effect to middle-aged men and women.

Six-month physical activity and fitness changes in Project Active, a randomized trial

PURPOSE

Project Active is a randomized clinical trial (N = 235) comparing a lifestyle physical activity program with a structured exercise program in changing physical activity (total energy expenditure [kcal.kg-1.d-1]) and cardiorespiratory fitness (VO2peak in mL.kg-1.min-1).

METHODS

Sedentary but healthy adults (N = 235) aged 35-60 years received 6 months of intensive intervention.

RESULTS

Analysis of covariance (ANCOVA), adjusting for baseline measure, age, gender, body mass index (BMI), cohort, and ethnicity, showed that at 6 months both lifestyle and structured groups significantly increased energy expenditure over baseline (P < 0.001). The mean increases +/- SE, 1.53 +/- 0.19 kcal.kg-1.d-1 for the lifestyle group and 1.34 +/- 0.20 kcal.kg-1 d-1 for the structured group, were not significantly different between groups (P = 0.49). For cardiorespiratory fitness, both groups had significant increases from baseline (P < 0.001). Mean increases +/- SE were 1.58 +/- 0.33 mL.kg-1.min-1 and 3.64 +/- 0.33 mL.kg-1.min-1 for the lifestyle and structured groups, respectively. This was significantly greater in the structured group (P < 0.001). We also studied changes in intensity of physical activity. Both groups significantly increased moderate intensity activity from baseline, but the increase was significantly greater in the lifestyle group than the structured group (P = 0.02). In contrast, the structured group increased its hard activity more than the lifestyle group, but the difference was not significantly different (P = 0.02). In contrast, the structured group increased its hard increased (P < 0.01) for both groups by 0.25 kcal.kg-1.d-1.

CONCLUSION

Both intervention approaches are effective for increasing physical activity and fitness over a 6-month period in initially sedentary men and women.

Influences of cardiorespiratory fitness levels and other predictors on cardiovascular disease mortality in men

PURPOSE

This investigation quantifies the relation between cardiorespiratory fitness levels and cardiovascular disease (CVD) mortality within strata of other CVD predictors.

METHODS

Participants included 25,341 male Cooper Clinic patients who underwent a maximal graded exercise test. CVD death rates were determined for low (least fit one-fifth), moderate (next two-fifths), and high (top two-fifths) cardiorespiratory fitness categories by strata of smoking habit, blood cholesterol level, resting blood pressure, and health status. There were 226 cardiovascular deaths during 211,996 man-years of follow-up.

RESULTS

For individuals with none of the major CVD predictors (smoking, elevated resting systolic blood pressure, elevated blood cholesterol), there was a strong inverse relation (P = 0.001) between fitness level and CVD mortality. An inverse relation between CVD mortality and fitness level was seen within strata of cholesterol levels and health status. No evidence of a trend (P = 0.60) for decreased mortality was seen across fitness levels for individuals with elevated systolic blood pressure; however, a strong inverse gradient (P < 0.001) was seen across fitness levels for individuals with normal systolic blood pressure. There was a tendency for association between high levels of fitness and decreased CVD mortality in smokers compared with low and moderately fit smokers (P < 0.076). There was no significant association between level of fitness and CVD mortality for individuals with multiple (two or more) predictors (P = 0.325). Approximately 20% of the 226 CVD deaths in the population studied were attributed to low fitness level.

CONCLUSIONS

Moderate and high levels of cardiorespiratory fitness seem to provide some protection from CVD mortality, even in the presence of well established CVD predictors.

Development of physical activity behaviors among children and adolescents

Physical activity is a key component of energy balance and is promoted in children and adolescents as a lifelong positive health behavior. Understanding the potential behavioral determinants necessitates understanding influences from three fundamental areas: 1) physiologic and developmental factors, 2) environmental factors, and 3) psychological, social, and demographic factors. The literature to date has generally investigated potential predictors of physical activity in children and adolescents in each of these three general areas, although existing data rely largely on cross-sectional studies in which it is difficult to distinguish a determinant from a correlate. In all likelihood, aspects of each of these three areas interact in a multidimensional way to influence physical activity in youth. This article reviews evidence of potential determinants of physical activity in children and adolescents and provides recommendations for future work.

A randomized trial of physical activity interventions: design and baseline data from project active

We report here the design and baseline data from Project Active, a 2-yr randomized trial designed to compare the effectiveness of a Lifestyle physical activity intervention with the traditional Structured exercise prescription approach. Primary outcome measures are energy expenditure in physical activity (estimated by kcal per kilogram of body weight of energy expenditure) and cardiorespiratory fitness (measured by maximal oxygen uptake). The participants, 235 initially sedentary and apparently healthy adults, were randomized into either the Lifestyle or Structured intervention groups. The Lifestyle treatment consists of a personalized approach that accounts for an individual's motivational readiness and preferences for integrating physical activity into daily routines. The Structured approach is the familiar exercise prescription that is based on a frequency, intensity, and duration formula. The primary hypothesis to be tested is that there will be a difference in physical activity and cardiorespiratory fitness measures between the two conditions at the end of 24 months. The secondary hypothesis is that both groups will make significant improvements from baseline in physical activity and cardiorespiratory fitness at the end of 6 months. Six months of active intervention are followed by 18 months of a tapered follow-up maintenance intervention in both groups. Primary outcome measures are measured after 6 and 24 months.

Relations of sit-up and sit-and-reach tests to low back pain in adults

The sit-up and sit-and-reach tests are found on nearly all youth and adult fitness tests because of the perceived relation between performance on these tests and low back pain. However, this relationship has not been well validated. Therefore, the purpose of the study was to examine the relationship between performance on these two common field tests of muscular strength and flexibility (the sit-up and the sit-and-reach tests) and self-reported low back pain (LBP). The sample included 2,747 adults with a mean age of 44.6 +/- 9.8 years. The 1-minute sit-up (mean = 30.9 +/- 10.6) and sit-and-reach tests (mean = 39.88 +/- 10.49 cm) were administered to participants as part of a voluntary clinical health and fitness evaluation between 1980 and 1990. Participants completed a mail-back survey in 1990 on musculoskeletal health problems. Low back pain was quantified by developing on ordinal variable from questionnaire responses which represented a range of severity of LBP from none (0) to LBP which required medical care (3). With an average of 6.1 (+/- 2.0) years of follow-up, LBP was reported by 54% of the study participants (men = 45%, women = 54%). Pearson correlations between sit-up (r = .002; p = .94), sit-and-reach (r = -.043; p = .03), and LBP indicated poor LBP criterion-related validity from the sit-up and sit-and-reach tests. Partial correlations, where age, gender, percent of body fat, and time between testing and survey response were controlled, displayed no increase in the relationship. This study does not support the validity of sit-up and sit-and-reach test items for health-related fitness batteries because they were unrelated to LBP.

Lower extremity morphology and alignment and risk of overuse injury

OBJECTIVE

Lower extremity alignment factors, including tibiofemoral angle, quadriceps angle (Q-angle), and limb length discrepancies, are commonly thought to be clinically relevant as contributing factors to overuse injuries of the lower extremities. To explore the scientific rationale for these clinical beliefs, we conducted a review of the available English language literature from 1966 to July 1997 relating overuse injury to lower extremity alignment.

DATA SOURCES

MEDLINE was searched for medical subject headings and title key words to locate published works relating lower extremity morphologic characteristics to risk of overuse injury. Additional references were reviewed from reprint collections and reference lists of published work.

DATA EXTRACTION AND SYNTHESIS

Relevant studies were reviewed for strengths and weaknesses in design, analysis, and conclusions. Synthesis across studies concentrated on commonalities and differences of methods in definition of exposure and outcome variables.

MAIN RESULTS

Six population-based studies have been conducted evaluating some aspect of lower extremity alignment as a risk factor for overuse injury. Three of these studies evaluated military recruits in basic training, two studied mixed groups of athletes and one studied folk dancers. The time frame across studies ranged from 12 weeks to 52 weeks. A key finding was the considerable variation in the measure of lower limb alignment used as the exposure variable, as well as the method of measurement used to quantify the exposure. Some studies relied on visual examination, whereas others used digitized photographic techniques. Moreover, each study varied in the definition used for overuse injury; outcomes ranged from self-reported cases of shin splints to radiographic confirmation of stress fracture. Five of the six studies evaluated some aspect of foot morphology, whereas only one evaluated full leg alignment parameters.

CONCLUSIONS

Results were conflicting but, in general, did not support clinical beliefs of the detrimental effects of decreased longitudinal foot arch and varus tibiofemoral alignment as risk factors for lower extremity overuse injury. Differences in methodologic rigor and outcome definition prevent a meaningful synthesis of existing work. Directions for future research are suggested.

Improvements in cardiorespiratory fitness attenuate age-related weight gain in healthy men and women: the Aerobics Center Longitudinal Study

OBJECTIVE

To determine the longitudinal relation of change in cardiopulmonary fitness to subsequent change in body weight in a cohort of healthy middle-aged adults.

DESIGN

Prospective cohort study.

SUBJECTS

Participants were 4599 men and 724 women (43 +/- 9 y) receiving at least three medical examinations between 1970 and 1994. Examinations included assessment of cardiorespiratory fitness by maximal exercise tests and measurement of body weight.

MEASUREMENTS

Change in fitness was calculated as the difference in maximal treadmill time between the first and second examination (mean interval, 1.8 y). Weight change was calculated as the difference in body weight between the first and last examination (mean follow-up, 7.5 y).

RESULTS

There was a small, yet statistically significant weight gain over the follow-up (0.61 +/- 5.29 kg for men and 1.51 +/- 4.67 kg for women; P << 0.001). Estimates from the multiple linear regression modeling show that each 1 min improvement in treadmill time, significantly attenuated weight gain in both men (b = -0.60; P << 0.001) and women (b = -0.60; P << 0.001), respectively. Moreover, each 1 min improvement in treadmill time, reduced the odds of a > or = 5 kg gain by 14% in men (odds ratios (OR)) = 0.86; 95% confidence interval (CI): 0.83-0.89) and by 9% in women (OR = 0.91; 95% CI:0.83-1.00) and the odds of a > or = 10 kg gain by 21% in both men (OR = 0.79;95% CI:0.75-0.84) and women (OR = 0.79;95% CI:0.67-0.93)

CONCLUSIONS

Improvements in fitness, appear important in attenuating age-related weight gain in healthy middle-aged adults. Thus, an active life-style should be promoted early and maintained through adulthood to prevent substantial weight gain and obesity with age.

Exaggerated blood pressure response to dynamic exercise and risk of future hypertension

This study examined the association between an exaggerated blood pressure response to treadmill exercise and the risk of developing hypertension. Subjects were healthy normotensive men (n = 5386) who had a baseline graded maximal exercise test between 1971 and 1982, and completed a mailed follow-up questionnaire. At follow-up in 1986, cases (n = 151) reported physician diagnosed hypertension and controls (n = 201) reported normotension. Those who had developed hypertension at follow-up were more likely to have had an exaggerated blood pressure response to exercise (OR = 2.4, 1.4-4.3). In multiple logistic regression analysis an exaggerated response was significantly associated (OR = 3.0, 1.5-6.1) with future hypertension after controlling for sitting systolic and diastolic blood pressure, weight change from age 21 to follow-up, entry age, family history of hypertension, body mass index, treadmill time, alcohol consumption, and years of follow-up. These results suggest that an exaggerated blood pressure response to exercise is independently associated with increased risk of future hypertension, and therefore, may be an important factor in determining hypertension risk.

Reduction in cardiovascular disease risk factors: 6-month results from Project Active

BACKGROUND

Project Active is a randomized clinical trial that compares a lifestyle physical activity intervention with a traditional structured exercise intervention. The purpose of this paper is to report 6-month results of these interventions on cardiovascular disease (CVD) risk factors among healthy, sedentary, middle-aged men and women, and to examine the psychological strategies used in each group (Lifestyle and Structured) to reach the level of physical activity recommended by the Centers for Disease Control and Prevention (CDC) and American College of Sports Medicine (ACSM) and to achieve changes in these CVD risk factors.

METHODS

A total of 116 initially sedentary men (mean +/- SD self-reported physical activity, 33.2 +/- 1.4 kcal.kg-1.day-1) and 119 women (32.9 +/- 1.0 kcal.kg-1.day-1), ages 35-60 years (46.0 +/- 6.7 years) were randomly assigned to a 6-month lifestyle physical activity counseling intervention or a 6-month gymnasium-based structured program. At baseline and 6 months, changes in lipid and lipoprotein-cholesterol concentrations, blood pressure, and body composition and cognitive and behavioral measures of change were assessed. One-way analyses of variance with covariate adjustment were used to test for between-group differences in CVD risk factors. Associations between achieving the CDC/ACSM criterion and changes in cognitive and behavioral measures were assessed with multiple logistic regression models.

RESULTS

After 6 months of intervention, 78% of Lifestyle participants and 85% of Structured participants were meeting or exceeding the CDC/ACSM recommendation of accumulating 30 min or more of moderate-intensity physical activity on most, preferably all, days of the week. This was verified by a significant increase in cardiorespiratory fitness in both groups. The adjusted mean increase in maximal METs (VO2peak divided by 3.5 ml.kg-1.min-1) between treadmill tests was 0.4 kcal.kg-1.hr-1 (P < 0.001) for Lifestyle and 1.1 kcal.kg-1.hr-1 (P < 0.001) for Structured. There was a significant difference between intervention groups for this outcome. Both groups had significant reductions in total cholesterol, total cholesterol/HDL-C ratio, diastolic blood pressure, and percentage of body fat. There were no significant between-group differences in changes in these outcomes. Adjusted mean changes in total cholesterol, systolic blood pressure, and percentage of body fat in Lifestyle [in Structured] participants were -0.2 [-0.3] mmol.L-1, -3.2[-1.8] mm Hg, and -1.4 [-1.7] %, respectively. There were significant associations between achieving the CDC/ACSM physical activity criterion and greater use of the cognitive and behavioral strategies of change. Both groups changed self-efficacy and many of the behavioral measures, but there were no significant differences between intervention groups.

CONCLUSIONS

These results demonstrate that lifestyle physical activity counseling is as effective as structured exercise programs in increasing physical activity and improving CVD risk factors after 6 months among initially sedentary men and women. Furthermore, specific cognitive and behavioral counseling strategies were increased significantly as a result of the intervention. These strategies are effective and could be used in a wide variety of settings.

Isometry measurements in the knee with the anterior cruciate ligament intact, sectioned, and reconstructed

When assessing isometry during anterior cruciate ligament surgery, it is assumed that points determined to be isometric remain so after reconstruction. We sought to evaluate if isometric measurements vary with the status of the anterior cruciate ligament. A computerized electronic isometer was used to measure the magnitude and pattern of change in separation distance between a constant point in the tibial insertion of the anterior cruciate ligament and five positions within the femoral insertion with the anterior cruciate ligament intact, sectioned, and reconstructed. For the center position, the magnitude and pattern of the change in separation distance was physiologically isometric in all conditions (maximal length change, 3.0 mm). For the posterior position, the isometry pattern remained physiologic in each condition, and the magnitude of the separation distance was nearly isometric in all conditions (maximal length change, 3.7 mm). The superior and inferior positions had similar isometric measurements in the intact and sectioned conditions but significantly different measurements after anterior cruciate ligament reconstruction. Intraoperative assessment of isometry at positions in the center or posterior portion of the anterior cruciate ligament's femoral insertion provides useful information that is not altered by reconstruction. For superior and inferior positions, however, points found to be isometric in the anterior cruciate ligament-deficient knee did not remain isometric after reconstruction.

The clinical value of serum ferritin tests in endurance athletes

OBJECTIVE

It is common practice to measure serum ferritin levels in endurance athletes because of the belief that low iron stores may compromise performance. The direct relationship between endurance performance and iron deficiency anemia is well known, but there are theoretical reasons to believe that endurance performance may be adversely affected by low iron stores even in the absence of frank anemia. The purpose of this article is to provide a critical review of the scientific evidence relating low iron stores to endurance performance.

DATA SOURCES

Medline was searched using MeSH for articles related to ferritin and endurance published since 1985. Additional references were reviewed from the bibliographies of the retrieved articles.

STUDY SELECTION

All clinical study designs were reviewed as well as relevant animal studies. Conclusions regarding endurance performance in humans were limited to data from clinical studies.

DATA EXTRACTION AND SYNTHESIS

In reviewing the literature, the relative strengths of the study designs were examined carefully. Particular attention of the effectiveness of each study in isolating ferritin as the key independent variable. Dependent measures of endurance capacity were also evaluated.

MAIN RESULTS

Eight studies isolated serum ferritin as the experimental variable. Only one study reported a significant improvement in endurance performance (time to exhaustion) in subjects with low ferritin levels treated with oral iron, but this finding may have been magnified by an unexplained decrease in time to exhaustion in the control group. Iron dosages differed in the studies reviewed. Two additional studies that reported increases in performance parameters following increases in ferritin were confounded by concomitant increases in hemoglobin levels.

CONCLUSIONS

Iron supplementation can raise serum ferritin levels, but increases in ferritin concentration, unaccompanied by increases in hemoglobin concentration, have not been shown to increase endurance performance. Of concern to the clinician is that athletes with low ferritin levels but hemoglobin in the low-normal range may have iron deficiency anemia responsive to iron supplementation. Low ferritin with hemoglobin in the mid- to upper normal range is at best a relative indication for iron supplementation: low ferritin with hemoglobin in the low normal range is a stronger, yet still relative, indication for iron supplementation in athletes.

Achilles tendonitis: are corticosteroid injections useful or harmful?

OBJECTIVE

The use of local corticosteroid injections for the treatment of Achilles tendonitis is controversial. Some authors advocate their use based on efficacy in accelerating the healing process of Achilles tendonitis; others feel the associated side effects should preclude their use altogether. The purpose of this study was to comprehensively review and critically appraise the available literature in order to examine the evidence concerning this clinical dilemma.

DATA SOURCES

MEDLINE was searched using MeSH and textwords for English- and French-language articles related to Achilles tendonitis and corticosteroids published since 1966. Additional references were reviewed from the bibliographies of the retrieved articles. The total number of articles reviewed was 145.

STUDY SELECTION

All clinical study designs were included as well as related animal studies using experimental and quasi-experimental designs.

DATA EXTRACTION AND SYNTHESIS

In reviewing the literature, particular attention was paid to the relative strengths of the different study designs. From these data, the factors associated with effectiveness and safety of injected corticosteroids were examined.

MAIN RESULTS

The only rigorous studies (one randomized controlled trial, one cohort study) showed no benefit of corticosteroids over placebo. In animal studies, corticosteroid injections decrease adhesion formation, temporarily weaken the tendon if given intratendinously, but have no effect on tendon strength if injected into the paratenon. The overall incidence of side effects with locally injected corticosteroids is approximately 1%. Most side effects are temporary, but skin atrophy and depigmentation can be permanent. Although there are many case reports of Achilles tendon rupture following local corticosteroid injection, there are no published rigorous studies that evaluate the risk of rupture with or without corticosteroid injection.

CONCLUSIONS

There are insufficient published data to determine the comparative risks and benefits of corticosteroid injections in Achilles tendonitis. The decreased tendon strength with intratendinous injections in animal studies suggests that rupture may be a potential complication for several weeks following injection.

Physical activity, physical fitness, and all-cause and cancer mortality: a prospective study of men and women

We studied physical fitness and physical activity in relation to all-cause and cancer mortality in a cohort of 7080 women and 25,341 men examined at the Cooper Clinic in Dallas, Texas, during 1970 to 1989. Physical fitness was assessed at baseline by a maximal treadmill exercise test, while physical activity was self-reported on the attendant health habits questionnaire. Both men and women averaged about 43 years of age at baseline (range, 20 to 88 years), and they were followed for approximately 8 years on average. Through the end of 1989, the women contributed 52,982 person-years of observation and incurred 89 deaths, including 44 deaths due to cancer. The men contributed 211,996 person-years and incurred 601 deaths, with 179 due to cancer. After adjustment for baseline differences in age, examination year, cigarette habit, chronic illnesses, and electrocardiogram abnormalities, we found a strong inverse association between risk of all-cause mortality and level of physical fitness in both men and women (P for trend < 0.001). Physically active men also were at lower risk of all-cause mortality than were sedentary ones (P for trend = 0.01). Among women, however, self-reported physical activity was not significantly related to risk of death from all causes. The risk of mortality from cancer declined sharply across increasing levels of fitness among men (P for trend < 0.001), whereas among women the gradient was suggestive but not significant (P for trend = 0.07). Physically active men also were at lower risk of death from cancer than were sedentary men (P for trend = 0.002), but among women physical activity was unrelated to cancer mortality.

Maximal exercise hemodynamics and risk of mortality in apparently healthy men and women

The purpose of this investigation was to determine the association of maximal exercise hemodynamic responses with risk of mortality due to all-causes, cardiovascular disease (CVD), and coronary heart disease (CHD) in a population of apparently healthy individuals. Study participants were 20,387 men (mean age = 42.2 yr) and 6,234 women (mean age = 41.9 yr), patients of a preventive medicine center in Dallas, TX, examined between 1971 and 1989. Maximal heart rate and maximal systolic blood pressure (SBP) measured during the maximal exercise test were related to risk of all-cause, CVD, and CHD mortality. During an average of 8.1 yr of follow-up, there were 348 deaths in men and 66 deaths in women. Among men, after adjustment for confounding variables, risks (and 95 percent confidence interval (CI)) of all-cause mortality for quartiles of maximal SBP, relative to the lowest quartile, were: 0.96 (0.70-1.33), 1.36 (1.01-1.85), and 1.37 (0.98-1.92) for quartiles 2-4, respectively. Similarly adjusted risks for maximal heart rate were: 0.61(0.44-0.85), 0.69 (0.51-0.93), and 0.60 (0.41-0.87). Similar results were seen for risk of CVD and CHD death. In women, similar trends in adjusted risks of all-cause and CVD mortality across maximal SBP and heart rate categories were observed. For maximal heart rate, a 35 bpm higher value was associated with a 36 percent decreased risk of CVD mortality in men (RR = 0.63,95 percent CI = 0.34-0.71) and an 8 percent lower risk in women (RR = 0.92,95 percent CI = 0.18-4.63). These results suggest that an exaggerated SBP or an attenuated heart rate response to maximal exercise may indicate an elevated risk for mortality in this apparently healthy population.

The association between cardiorespiratory fitness and prostate cancer

We conducted a prospective study to assess the association between cardiorespiratory fitness and prostate cancer. The subjects were men, aged 20-80 yr, who received a preventive medical exam at the Cooper Clinic in Dallas, TX, during 1970-1989 and provided information on cardiorespiratory fitness and prostate cancer (N = 12,975). Cardiorespiratory fitness was assessed at a baseline examination between 1971 and 1989 using a maximal exercise treadmill test. Questionnaires were mailed to the men in 1982 and 1990 to ascertain incident cases of prostate cancer. Ninety-four cases of incident prostate cancer were identified. Higher cardiorespiratory fitness levels were inversely associated with the probability of development of incident prostate cancer after controlling for age, body mass index, and smoking habits; adjusted estimates of the incidence rate ratio declined from 1.1 (95% CI 0.63-1.77) to 0.73 (95% CI 0.41-1.29) to 0.26 (95% CI 0.10-0.63) across increasing quartiles of fitness (P for trend < 0.004). This protective effect was limited to participants < 60 yr old. Also, an inverse association was observed between physical activity and prostate cancer. Compared with expending < 1000 kcal.wk-1, participants who expended 1000- < 2000, 2000- < 3000, or > or = 3000 kcal.wk-1 had adjusted incidence rate ratios of 0.37 (95% CI 0.17-0.79), 0.62 (95% CI 0.27-1.41), and 0.37 (95% CI 0.14-0.98), respectively. The results suggest that cardiorespiratory fitness and physical activity levels may protect against the development of incident prostate cancer.

Food-frequency questionnaire validation among Mexican-Americans: Starr County, Texas

A food-frequency questionnaire (FFQ) for low-income Mexican-Americans in Starr County, Texas, was developed as part of an epidemiologic study of gallbladder disease during 1985 and 1986. The FFQ was developed from 7-day food records collected from the first sample. In the validity study, using the second sample, correlations between nutrients calculated from 3-day food records and the FFQ were 0.77, 0.76, and 0.61 for energy, total fat, and saturated fat, respectively. In the reliability study, using the third sample, for the 1-month interval between baseline and a repeat FFQ measurement correlations ranged from 0.90 for energy to 0.85 for total fat and for the 2-month interval they were 0.84 for energy and 0.70 for total fat. The high correlations are largely explained by the lack of diversity in the diets of Starr County individuals which facilitated the high agreement between the FFQ and the food records for estimates of energy, fats, and cholesterol.

Changes in physical fitness and all-cause mortality. A prospective study of healthy and unhealthy men

OBJECTIVE

To evaluate the relationship between changes in physical fitness and risk of mortality in men.

DESIGN

Prospective study, with two clinical examinations (mean interval between examinations, 4.9 years) to assess change or lack of change in physical fitness as associated with risk of mortality during follow-up after the subsequent examination (mean follow-up from subsequent examination, 5.1 years).

SETTING

Preventive medicine clinic.

STUDY PARTICIPANTS

Participants were 9777 men given two preventive medical examinations, each of which included assessment of physical fitness by maximal exercise tests and evaluation of health status.

MAIN OUTCOME MEASURES

All cause (n = 223) and cardiovascular disease (n = 87) mortality.

RESULTS

The highest age-adjusted all-cause death rate was observed in men who were unfit at both examinations (122.0/10,000 man-years); the lowest death rate was in men who were physically fit at both examinations (39.6/10,000 man-years). Men who improved from unfit to fit between the first and subsequent examinations had an age-adjusted death rate of 67.7/10,000 man-years. This is a reduction in mortality risk of 44% (95% confidence interval, 25% to 59%) relative to men who remained unfit at both examinations. Improvement in fitness was associated with lower death rates after adjusting for age, health status, and other risk factors of premature mortality. For each minute increase in maximal treadmill time between examinations, there was a corresponding 7.9% (P = .001) decrease in risk of mortality. Similar results were seen when the group was stratified by health status, and for cardiovascular disease mortality.

CONCLUSIONS

Men who maintained or improved adequate physical fitness were less likely to die from all causes and from cardiovascular disease during follow-up than persistently unfit men. Physicians should encourage unfit men to improve their fitness by starting a physical activity program.