The effect of regular running on the bone tissue of middle-aged men and women

BACKGROUND

Many authors consider running to be a protective physical activity (PA) in bone health. However, many studies also show inconsistencies in their results. The objective of the study is to analyze the effect of cumulative loading rate (TCL) on the bone mass of middle-aged runners and non-runners is assessed.

METHODS

This cross-sectional study included 322 individuals. There were 212 runners (109 male, 103 female) and those were individuals who did >10 km of running per week. There were 110 non-runners (54 male, 56 female). This group included individuals who did not adhere to the WHO (2020) recommendations for PA. The average age in the individual groups ranged from 40.9±4.1 to 42.3±4.8 years. Bone parameters were measured on the lower extremities and vertebral spine using the DXA method (Hologic QDR Horizon A). Multi-regression dependencies analysis was used to assess the results.

RESULTS

The results of the multi-regression dependencies analysis showed that the bone mineral content (BMC) and bone mineral density (BMD) are significantly influenced by the TCL and gender.

CONCLUSIONS

Therefore, we can conclude that running could be a suitable PA for preventing the reduction of BMD in the middle-aged population, especially in the lower limbs.

Lifestyle Walking Intervention for Patients With Heart Failure With Reduced Ejection Fraction: The WATCHFUL Trial

BACKGROUND

Physical activity is pivotal in managing heart failure with reduced ejection fraction, and walking integrated into daily life is an especially suitable form of physical activity. This study aimed to determine whether a 6-month lifestyle walking intervention combining self-monitoring and regular telephone counseling improves functional capacity assessed by the 6-minute walk test (6MWT) in patients with stable heart failure with reduced ejection fraction compared with usual care.

METHODS

The WATCHFUL trial (Pedometer-Based Walking Intervention in Patients With Chronic Heart Failure With Reduced Ejection Fraction) was a 6-month multicenter, parallel-group randomized controlled trial recruiting patients with heart failure with reduced ejection fraction from 6 cardiovascular centers in the Czech Republic. Eligible participants were ≥18 years of age, had left ventricular ejection fraction <40%, and had New York Heart Association class II or III symptoms on guidelines-recommended medication. Individuals exceeding 450 meters on the baseline 6MWT were excluded. Patients in the intervention group were equipped with a Garmin vívofit activity tracker and received monthly telephone counseling from research nurses who encouraged them to use behavior change techniques such as self-monitoring, goal-setting, and action planning to increase their daily step count. The patients in the control group continued usual care. The primary outcome was the between-group difference in the distance walked during the 6MWT at 6 months. Secondary outcomes included daily step count and minutes of moderate to vigorous physical activity as measured by the hip-worn Actigraph wGT3X-BT accelerometer, NT-proBNP (N-terminal pro-B-type natriuretic peptide) and high-sensitivity C-reactive protein biomarkers, ejection fraction, anthropometric measures, depression score, self-efficacy, quality of life, and survival risk score. The primary analysis was conducted by intention to treat.

RESULTS

Of 218 screened patients, 202 were randomized (mean age, 65 years; 22.8% female; 90.6% New York Heart Association class II; median left ventricular ejection fraction, 32.5%; median 6MWT, 385 meters; average 5071 steps/day; average 10.9 minutes of moderate to vigorous physical activity per day). At 6 months, no between-group differences were detected in the 6MWT (mean 7.4 meters [95% CI, -8.0 to 22.7]; P=0.345, n=186). The intervention group increased their average daily step count by 1420 (95% CI, 749 to 2091) and daily minutes of moderate to vigorous physical activity by 8.2 (95% CI, 3.0 to 13.3) over the control group. No between-group differences were detected for any other secondary outcomes.

CONCLUSIONS

Whereas the lifestyle intervention in patients with heart failure with reduced ejection fraction improved daily steps by about 25%, it failed to demonstrate a corresponding improvement in functional capacity. Further research is needed to understand the lack of association between increased physical activity and functional outcomes.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03041610.

Statistical analysis plan for a randomized controlled trial examining pedometer-based walking intervention in patients with heart failure with reduced ejection fraction: the WATCHFUL trial

BACKGROUND

Physical activity is an effective management strategy for heart failure with reduced ejection fraction, but patients' compliance is challenging. Walking is a suitable form of physical activity due to its convenience and sustainability, and it can potentially improve functional capacity in heart failure patients.

OBJECTIVES

The WATCHFUL trial aims to determine whether a pedometer-based walking intervention combined with face-to-face sessions and regular telephone contact improves functional capacity in heart failure patients.

METHODS

The WATCHFUL trial is a 6-month multicenter, parallel-group, randomized, controlled, superiority trial with a 6-month follow-up. A total of 202 patients were recruited for the trial. The primary analysis will evaluate the change in distance walked during the 6-min walk test from baseline to 6 months based on the intention-to-treat population; the analysis will be performed using a linear mixed-effect model adjusted for baseline values. Missing data will be imputed using multiple imputations, and the impact of missing data will be assessed using a sensitivity analysis. Adverse events are monitored and recorded throughout the trial period.

DISCUSSION

The trial has been designed as a pragmatic trial with a scalable intervention that could be easily translated into routine clinical care. The trial has been affected by the COVID-19 pandemic, which slowed patients' recruitment and impacted their physical activity patterns.

CONCLUSIONS

The present publication provides details of the planned statistical analyses for the WATCHFUL trial to reduce the risks of reporting bias and erroneous data-driven results.

TRIAL REGISTRATION

ClinicalTrials.gov (identifier: NCT03041610, registered: 3/2/2017).

Changes in the body composition of boys aged 11-18 years due to COVID-19 measures in the Czech Republic

BACKGROUND

The lockdown measures related to coronavirus disease 2019 (COVID) impacted the health of adolescents by reducing physical activity (PA). The physical changes in response to decreases in PA can be measured with full body composition analysis. The aim of this study was to evaluate the effects of long-term PA restrictions on body fat (BF), fat-free mass (FFM) and skeletal muscle mass (SMM) in adolescents.

METHODS

A total of 1669 boys (before PA restriction (G1): 998; after PA restrictions ended (G2): 671; between the ages of 11 and 18 were included. The measured parameters were body mass (BM), visceral fat area (VFA), BF, FFM and SMM. The whole-body composition was evaluated using bioelectrical impedance analysis (BIA).

RESULTS

Compared to G1, G2 exhibited an increase in BF between 1.2 and 5.1%. This difference was significant in boys aged 13 to 18 years (p < 0.05). VFA increased between 5.3 and 20.5 cm²; this increase was significant in boys aged 13 to 18 years (p < 0.05). SMM decreased between 2.6 and 3.8%, and this decrease was significant in all age groups (p < 0.05). Changes in body composition were not accompanied by any significant changes in BM.

CONCLUSIONS

COVID-19 restrictions reduced PA, resulting in a significant decrease in SMM. This decrease may impact boys' ability to engage in sufficiently varied PA, which may lead to a further decline in PA and subsequent medical consequences in adulthood.

The detrimental effect of COVID-19 nationwide quarantine on accelerometer-assessed physical activity of heart failure patients

AIMS

A reduction of habitual physical activity due to prolonged COVID-19 quarantine can have serious consequences for patients with cardiovascular diseases, such as heart failure. This study aimed to explore the effect of COVID-19 nationwide quarantine on accelerometer-assessed physical activity of heart failure patients.

METHODS AND RESULTS

We analysed the daily number of steps in 26 heart failure patients during a 6-week period that included 3 weeks immediately preceding the onset of the quarantine and the first 3 weeks of the quarantine. The daily number of steps was assessed using a wrist-worn accelerometer worn by the patients as part of an ongoing randomized controlled trial. Multilevel modelling was used to explore the effect of the quarantine on the daily step count adjusted for weather conditions. As compared with the 3 weeks before the onset of the quarantine, the step count was significantly lower during each of the first 3 weeks of the quarantine (P < 0.05). When the daily step count was averaged across the 3 weeks before and during the quarantine, the decrease amounted to 1134 (SE 189) steps per day (P < 0.001), which translated to a 16.2% decrease.

CONCLUSIONS

The introduction of the nationwide quarantine due to COVID-19 had a detrimental effect on the level of habitual physical activity in heart failure patients, leading to an abrupt decrease of daily step count that lasted for at least the 3-week study period. Staying active and maintaining sufficient levels of physical activity during the COVID-19 pandemic are essential despite the unfavourable circumstances of quarantine.

Validity of six consumer-level activity monitors for measuring steps in patients with chronic heart failure

INTRODUCTION

Although numerous activity trackers have been validated in healthy populations, validation is lacking in chronic heart failure patients who normally walk at a slower pace, making it difficult for researchers and clinicians to implement activity monitors during physical activity interventions.

METHODS

Six consumer-level activity monitors were validated in a 3-day field study in patients with chronic heart failure and healthy individuals under free living conditions. Furthermore, the same devices were evaluated in a lab-based study during treadmill walking at speeds of 2.4, 3.0, 3.6, and 4.2 km·h-1. Concordance correlation coefficients (CCC) were used to evaluate the agreement between the activity monitors and the criterion, and mean absolute percentage errors (MAPE) were calculated to assess differences between each device and the criterion (MAPE <10% was considered as a threshold for validity).

RESULTS

In the field study of healthy individuals, all but one of the activity monitors showed a substantial correlation (CCC ≥0.95) with the criterion device and MAPE <10%. In patients with heart failure, the correlation of only two activity monitors (Garmin vívofit 3 and Withings Go) was classified as at least moderate (CCC ≥0.90) and none of the devices had MAPE <10%. In the lab-based study at speeds 4.2 and 3.6 km·h-1, all activity monitors showed substantial to almost perfect correlations (CCC ≥0.95) with the criterion and MAPE in the range 1%-3%. However, at slower speeds of 3.0 and 2.4 km·h-1, the accuracy of all devices substantially deteriorated: their correlation with the criterion decreased below 90% and their MAPE increased to 4-8% and 10-45%, respectively.

CONCLUSIONS

Even though none of the tested activity monitors fall within arbitrary thresholds for validity, most of them perform reasonably well enough to be useful tools that clinicians can use to simply motivate chronic heart failure patients to walk more.

A pedometer-based walking intervention with and without email counseling in general practice: a pilot randomized controlled trial

BACKGROUND

General practitioners play a fundamental role in combatting the current epidemic of physical inactivity, and pedometer-based walking interventions are able to increase physical activity levels of their patients. Supplementing these interventions with email counseling driven by feedback from the pedometer has the potential to further improve their effectiveness but it has to be yet confirmed in clinical trials. Therefore, the aim of our pilot randomized controlled trial is to evaluate the feasibility and potential efficacy of future trials designed to assess the additional benefit of email counseling added to a pedometer-based intervention in a primary care setting.

METHODS

Physically inactive patients were opportunistically recruited from four general practices and randomized to a 12-week pedometer-based intervention with or without email counseling. To explore the feasibility of future trials, we assessed the speed and efficiency of recruitment, adherence to wearing the pedometer, and engagement with email counseling. To evaluate the potential efficacy, daily step-count was the primary outcome and blood pressure, waist and hip circumference, and body mass were the secondary outcomes. Additionally, we conducted a qualitative analysis of structured interviews with the participating general practitioners.

RESULTS

The opportunistic recruitment has been shown to be feasible and acceptable, but relatively slow and inefficient; moreover, general practitioners selectively recruited overweight and obese patients. Patients manifested high adherence, wearing the pedometer on 83% (± 20) of days. All patients from the counseling group actively participated in email communication and responded to 46% (± 22) of the emails they received. Both groups significantly increased their daily step-count (pedometer-plus-email, + 2119, p = 0.002; pedometer-alone, + 1336, p = 0.03), but the difference between groups was not significant (p = 0.18). When analyzing both groups combined, there was a significant decrease in body mass (- 0.68 kg, p = 0.04), waist circumference (- 1.73 cm, p = 0.03), and systolic blood pressure (- 3.48 mmHg, p = 0.045).

CONCLUSIONS

This study demonstrates that adding email counseling to a pedometer-based intervention in a primary care setting is feasible and might have the potential to increase the efficacy of such an intervention in increasing physical activity levels.

TRIAL REGISTRATION

The trial was retrospectively registered at ClinicalTrials.gov (ID: NCT03135561 , date: April 26, 2017).

Effect of a 6-month pedometer-based walking intervention on functional capacity in patients with chronic heart failure with reduced (HFrEF) and with preserved (HFpEF) ejection fraction: study protocol for two multicenter randomized controlled trials

Background

Regular physical activity is recommended for patients with chronic heart failure to improve their functional capacity, and walking is a popular, effective, and safe form of physical activity. Pedometers have shown potential to increase the amount of walking across a range of chronic diseases, but it is unknown whether a pedometer-based intervention improves functional capacity and neurohumoral modulation in heart failure patients.

Methods

Two multicenter randomized controlled trials will be conducted in parallel: one in patients with chronic heart failure with reduced ejection fraction (HFrEF), the other in patients with chronic heart failure with preserved ejection fraction (HFpEF). Each trial will consist of a 6-month intervention with an assessment at baseline, at 3 months, at the end of the intervention, and 6 months after completing the intervention. Each trial will aim to include a total of 200 physically inactive participants with chronic heart failure who will be randomly assigned to intervention or control arms. The 6-month intervention will consist of an individualized pedometer-based walking program with weekly step goals, behavioral face-to-face sessions with a physician, and regular telephone calls with a research nurse. The intervention will be based on effective behavioral principles (goal setting, self-monitoring, personalized feedback). The primary outcome is the change in 6-min walk distance at the end of the 6-month intervention. Secondary outcomes include changes in serum biomarkers levels, pulmonary congestion assessed by ultrasound, average daily step count measured by accelerometry, anthropometric measures, symptoms of depression, health-related quality of life, self-efficacy, and MAGGIC risk score.

Discussion

To our knowledge, these are the first studies to evaluate a pedometer-based walking intervention in patients with chronic heart failure with either reduced or preserved ejection fraction. The studies will contribute to a better understanding of physical activity promotion in heart failure patients to inform future physical activity recommendations and heart failure guidelines.

Trial registration The trials are registered in ClinicalTrials.gov, identifiers: NCT03041610, registered 29 January 2017 (HFrEF), NCT03041376, registered 1 February 2017 (HFpEF)

Airflow limitation is accompanied by diaphragm dysfunction

Chronic airflow limitation, caused by chronic obstructive pulmonary disease (COPD) or by asthma, is believed to change the shape and the position of the diaphragm due to an increase in lung volume. We have made a comparison of magnetic resonance imaging (MRI) of diaphragm in supine position with pulmonary functions, respiratory muscle function and exercise tolerance. We have studied the differences between patients with COPD, patients with asthma, and healthy subjects. Most interestingly we found the lung hyperinflation leads to the changes in diaphragmatic excursions during the breathing cycle, seen in the differences between the maximal expiratory diaphragm position (DPex) in patients with COPD and control group (p=0.0016). The magnitude of the diaphragmatic dysfunction was significantly related to the airflow limitation expressed by the ratio of forced expiratory volume in 1 s to slow vital capacity (FEV(1)/SVC), (%, p=0.0007); to the lung hyperinflation expressed as the ratio of the residual volume to total lung capacity (RV/TLC), (%, p=0.0018) and the extent of tidal volume constrain expressed as maximal tidal volume (V(Tmax)), ([l], p=0.0002); and the ratio of tidal volume to slow vital capacity (V(T)/SVC), (p=0.0038) during submaximal exercise. These results suggest that diaphragmatic movement fails to contribute sufficiently to the change in lung volume in emphysema. Tests of respiratory muscle function were related to the position of the diaphragm in deep expiration, e.g. neuromuscular coupling (P(0.1)/V(T)) (p=0.0232). The results have shown that the lung volumes determine the position of the diaphragm and function of the respiratory muscles. Chronic airflow limitation seems to change the position of the diaphragm, which thereafter influences inspiratory muscle function and exercise tolerance. There is an apparent relationship between the position of the diaphragm and the pulmonary functions and exercise tolerance.

Body composition of elite female players in five different sports games

The goal of this study was to identify and compare body composition (BC) variables in elite female athletes (age ± years): volleyball (27.4 ± 4.1), softball (23.6 ± 4.9), basketball (25.9 ± 4.2), soccer (23.2 ± 4.2) and handball (24.0 ± 3.5) players. Fat-free mass (FFM), fat mass, percentage of fat mass (FMP), body cell mass (BCM), extracellular mass (ECM), their ratio, the percentage of BCM in FFM, the phase angle (α), and total body water, with a distinction between extracellular (ECW) and intracellular water, were measured using bioimpedance analysis. MANOVA showed significant differences in BC variables for athletes in different sports (F60.256 = 2.93, p < 0.01, η2 = 0.407). The results did not indicate any significant differences in FMP or α among the tested groups (p > 0.05). Significant changes in other BC variables were found in analyses when sport was used as an independent variable. Soccer players exhibited the most distinct BC, differing from players of other sports in 8 out of 10 variables. In contrast, the athletes with the most similar BC were volleyball and basketball players, who did not differ in any of the compared variables. Discriminant analysis revealed two significant functions (p < 0.01). The first discriminant function primarily represented differences based on the FFM proportion (volleyball, basketball vs. softball, soccer). The second discriminant function represented differences based on the ECW proportion (softball vs. soccer). Although all of the members of the studied groups competed at elite professional levels, significant differences in the selected BC variables were found. The results of the present study may serve as normative values for comparison or target values for training purposes.

Is repeated-sprint ability of soccer players predictable from field-based or laboratory physiological tests?

AIM

The aim of this study was to investigate multiple regression models with prediction equations that would enable a valid estimate of running repeated-sprint ability (RSA) in soccer players from the variables measured in field and laboratory physiological tests.

METHODS

Adolescent soccer players (N=33) performed five field performance tests and two laboratory tests for assessment of muscle strength of legs, sprint ability, anaerobic power and capacity, aerobic power and capacity, and running economy. These tests served as potential predictors of RSA. RSA was assessed by a intermittent anaerobic running test (IAnRT) consisted of ten 20 m sprints.

RESULTS

Multiple regression analysis revealed that the mean speed in the 20 m sprint test and the 2 km endurance running test accounted for 89% of total variation in the mean running speed in the IAnRT (VIAnRT) as the indicator of capacity for multiple sprint work (R2=0.89, SEM=0.09 m.s-1). Using the variables from the laboratory tests, the best prediction of the VIAnRT was obtained from the running speed at the ventilatory threshold level (VVT) and anaerobic power (Pmax.kg-1) (R2=0.49, SEM=0.21 m.s-1).

CONCLUSION

Performance in the multiple-sprint exercise as an indicator of RSA can be estimated by the regression equation with two predictors - mean speed in the 20 m sprint and 2 km running test with an error of 4%.

[Relation between pelvis malposition and functional knee pain by long distance running]

PURPOSE

During endurance run knee problems often appear. This study wants to show the connection between a one- sided malposition of the pelvis and knee joint pain during endurance running.

METHOD

We tested endurance runners which had pelvis malposition and knee pain. Therefore 100 athletes were tested, 50 with knee pain and 50 without knee pain. Manual examination and clinical instruments were used for examination of sacroiliac joints for measurement of vertical distances between spinae iliacae anteriores superiores. Collected data were analyzed by appropriate statistical methods.

RESULTS

The results show that there is a connection between a one- sided pelvic malposition and knee pain during endurance running. These relations are probably realized by changes in lower extremity dysfunction as a result of pathological chains. The one sided pelvis malposition was in the control group significant higher (0.9 ± 0.4 cm) than in the control group (0.3 ± 0.2 cm).

CONCLUSION

There is a correlation between knee pain and os coxae malposition. (It is necessary in examine and treat the the cause- and effect chain to prevent injuries).

[Prospects of body composition analysis by bioimpedance method in children]

BACKGROUND

Increases in juvenile overweight and obesity have emphasized the importance of accurate and accessible body composition (BC) assessment, namely for the monitoring, prevention and treatment. Bioimpedance analysis seems to be one of the simple, safe, and inexpensive methods for assessment of the body composition in paediatric subjects

METHODS AND RESULTS

Three-thousand-twelve children aged 6-14 years (1611 - 53.5 % boys, and 1401 - 46.5 % girls) were evaluated BC using mono frequency and multi-frequency bioimpedance analyser with adapted prediction equation for Czech children. In both genders %BF decreased significantly with age (r = -0.698 in boys and r = -0.681 in girls, both p<0.0005). Linear regression analysis showed a significant positive relationship between %BF measured with BMI %BF(%)= 0.921*BMI(kg.m(-2)) -4.292, r = 0.858, r(2) = 0.736, SEE = 1.22 % in boys, and in girls %BF(%) = 1.284*BMI(kg.m(-2)) - 6.906, r = 0.903, r(2) = 0.815, SEE = 1.05 %, p<0.0001 in both cases.

CONCLUSIONS

BIA method is a useful method for detecting BC in children and can be accepted as a precise tool for measuring of BC in epidemiological studies in children. The decisive role for the use of this method has the population oriented prediction equation and the subject's hydration state.

[Motor skills testing in patients with chronic renal failure]

BACKGROUND

During chronic renal failure, number of complex metabolic and endocrinal changes in organism can develop, which in consequence lead to an inception of associate complications and in principle change the activity of all organ systems. Functional capacity of the chronically dialysed patients is limited, muscle strength is decreased, joint mobility is limited and the muscular imbalance is frequently found. According to the recent literature, an acceptable choice of exercise activity could contribute to prevention of disturbances and improve the patient's status. An essential part of each exercise program for these patients is an acceptable motor tests battery (1, 2, 3, 4, 5, 6 and 7). The aim of our study was to choose an acceptable motor tests battery, which should target such components of motor performance, whose certain rate is necessary for self-sufficiency keeping and perform activities of daily living.

METHODS AND RESULTS

We observed mixed group of 23 patients. For evaluation of the functional condition we used the "Senior Fitness Test Manual" (8), which measures these physical attributes: muscle strength, physical endurance, flexibility, agility and balance. The input results we compared with population standard specification used in the test battery. Results of the tests showed that the group of patients in comparison with the population standard specification have reached subnormal and risk performances, especially in tests requiring for its implementation muscular strength of lower extremities and physical efficiency. Normal and above normal performances we observed in patients that were physically active before and during regular dialysis treatment.

CONCLUSIONS

After the evaluation of result, we consider the selected battery of motor tests as an acceptable choice for motor skills testing in renal dialysed patients all age categories.

[Effect of body composition on physical fitness and functional capacity in obese women]

BACKGROUND

Both the high body fatness and low aerobic fitness have been shown to be risk factors for cardiovascular disease and type 2 diabetes. It is still unclear, whether these factors are related to each other or if they are independent risk factors. The objective of this study was to assess the influence of body composition on aspects of aerobic fitness in obese women.

METHODS AND RESULTS

Relative body fat was measured in a group of 31 obese women differing in age (25-54 years) by dual energy X-ray absorbtiometry (DEXA), in range of 40,8-58,8% of the body fat. Intracellular and extracellular fractions of the fat free mass were assessed by bioimpedance analysis. Maximal power output and maximal oxygen consumption were measured by stepwise load test on bicycle ergometer. Mean values of absolute and relative VO2max expressed per kg body mass and per kg fat-free mass were 2,09+/-0,38 l x min(-1), 22,82+/-3,79 ml x min(-1) kg(-1), and 44,05+/-7,03 ml x min(-1) x kg(-1), respectively. Absolute VO2max was positively related to body weight (R=0,4758; P<0,01), BMI (R=0,5004; P<0,01), fat-free mass (R=0,5138; P<0,01) and body cell mass (R=0,4983; P<0,01). No significant dependence of relative VO2max per kg body mass on the body fat was identified.

CONCLUSIONS

Aerobic fitness, expressed by relative maximal oxygen consumption per kg of body weight, is not influenced by the percent of body fat in obese women. Body cell mass is markedly related to aerobic fitness, expressed by absolute maximal oxygen consumption in obese women.

[The use of bioimpedance analysis for the assessment of relative body fat in obese women]

BACKGROUND

Bioimpedance analysis (BIA) is often used for the assessment of relative body fat (%BF). The accuracy of the test depends on prediction equation used, which respects the group of population, body composition, age and gender of the individual. The requirement to construct a specific prediction equation for obese population with more than 30% body fat was suggested. The objective of the study was to evaluate the validity of bioimpedance analysis and to develop population-specific prediction equation for obese women.

METHODS AND RESULTS

Relative body fat were measured in set of 63 obese women by means of 3 methods: tetrapolar bioimpedance analysis, bipedal bioimpedance analysis and dual energy X-ray absorbtiometry (DEXA). Significant differences were found among mean values of %BF measured by methods above (39.9%, 42.2% and 48.7%, respectively). Significant correlation between results obtained by tetrapolar BIA and by DEXA method was noticed (R=0.73). New specific prediction equation was developed for measuring %BF of obese women by tetrapolar BIA. No good agreement between bipedal BIA and DEXA method was found.

CONCLUSIONS

By using the new prediction equation, measurement of the relative body fat in obese women by tetrapolar bioimpedance analysis was comparable with the reference DEXA method.

Physiological profile of very young soccer players

BACKGROUND

There is still much uncertainty and debate surrounding the physiological requirements of competitive soccer. The coaching emphasis on skill development, deficiencies in fitness training, conservative training methods lead to difficulty in the scientific study of soccer.

METHODS

The physiological profiles of 22 young soccer players (mean age = 8.0+/-0.3 years, body mass = 28.2+/-3.2 kg, body height = 132.4+/-4.3 cm and body fat = 19.4+/-1.6 percent) were measured by the incremental exercise protocol on the treadmill with 5 percent inclination. All boys systematically trained at least 2 years with a minimum of two training units per week. During preseason, they trained two times per week, and during the competitive season they trained at least three times and competed in one or two games per week.

RESULTS

Mean VO2max x kg(-1) was 56.7+/-4.9 ml x kg(-1) x min(-1). Mean value of maximal running speed on a treadmill with 5 percent of inclination was 12.0+/-0.9 km x h(-1). Mean values of Rmax = 1.11+/-0.07. The selected functional variables at the ventilatory threshold (VT) level corresponded to VO2 x kg(-1) = 42.9+/-5.0 ml x kg(-1) x min(-1), mean values of percent VO2max x kg(-1) at VT level were 76.5+/-1.3 percent, mean speed of running was 10.5+/-1.2 km x h(-1), mean values of percent Vmax at VT level were 87.5+/-1.9 percent. The mean of energy cost of running was 4.28+/-0.19 J x kg(-1) x m(-1). According to our results, we can conclude that the physiological characteristics of young soccer players about 8 years old should be as follows: VO2max x kg(-1) higher than 55 ml x kg(-1) x min(-1) in defenders, and higher than 60 ml x kg(-1) x min(-1), in midfielders and forwards. Maximal speed of running on the treadmill with 5 percent of inclination should be higher than 12 km x h(-1) in all players, the running speed at anaerobic threshold (5 percent) higher than 10.5 km x h(-1), percent VO2max at anaerobic threshold level higher than 77.0 percent, and the energy cost of running lower than 4.20 J x kg(-1) x m(-1).

CONCLUSIONS

As in other sports where skills play a decisive role, the physiological data cannot be the sole predictor of competitive success. On the other hand, we must note that these physiological norms and standards are necessary conditions for success in high levels of soccer competition. The norms play decisive role in talent selection.

Energy cost of treadmill running in non-trained females differing in body fat

BACKGROUND

The energy demands of movement may be characterised by the energy cost C, which indicates how much energy is needed to carry a body mass of 1 kg over a distance of 1 m. It is generally accepted that the lower C represents a lesser amount of mechanical work executed with the same efficiency. The purpose of this study was to assess the influence of body fat on energy cost of running in healthy non-trained females.

METHODS

Energy cost of running (C) was determined on the treadmill in a group of healthy non-trained females (N=63, mean age=39.+/-10.2 years, body mass=64.6+/-5.5 kg, height= 166.2+/-5.7 cm, VO2max.kg(-1)=35.0+/-3.6 ml.kg(-1)min(-1)), differing significantly in the percentage of body fat (18.9-30.2%), assessed by the 10 skinfold measurements.

RESULTS

Mean value of C was 3.97+/-0.07 J.kg(-1)m(-1). The lowest values of C were found in subjects with the lowest %BF (C ranged from 3.81 to 4.06 J.kg(-1).m(-1)). There is a significant positive correlation between C and %BF [C (J.kg(-1).m(-1))= 0.0185*%BF (%) + 3.5090; r=0.7805; p<0.001; r2=0.6091], C and body mass (BM) [C (J.kg(-1).m(-1)) = 0.0083*BM (kg) + 3.4384; r=0.6176; p<0.001; r2 = 0.3814], and C and free fat mass (FFM) [C (J.kg(-1).m(-1))=0.0087*FFM (kg) + 3.5543; r=0.3521; p<0.05; r2=0.1240]. There is a negative correlation between C and VO2max.kg(-1) [C (J.kg(-1).m(-1))=-0.0181* VO2max.kg(-1) (ml.kg(-1).min(-1)) +4.6071; r=-0.8810; p<0.0001; r2=0.7761], and VO2max.kg(-1) and %BF [VO2max.kg(-1) (ml.kg(-1).min(-1)) =-0.8401* %BF(%) + 54.1021; r=-0.7142; p<0.0001; r2=0.5101].

CONCLUSIONS

From the collected data for untrained females we may conclude: first, the higher the training state (VO2max.kg(-1)), the lower the energy cost of running. Second, the energy cost of running C increases with the increase in body mass, %BF and FFM. Third, the training state decreases (VO2max.kg(-1)) with the increase in %BF.

Walking in visually handicapped children and its energy cost

Walking is a basic activity in visually handicapped subjects, and often it is used as a general means of improving physical fitness. The level of adaptation to walking may be assessed by means of energy cost, c. The variable c was studied during walking on a treadmill in two groups of visually handicapped children (international classification of vision of 5/200 or less). The two groups were comprised of 15 boys (mean age = 11.8 +/- 2.1 years) and 13 girls (mean age = 11.6 +/- 3.1 years). The mean energy cost in boys was found to be 3.79 +/- 0.31 J kg(-1) m(-1) and in girls it was 3.77 +/- 0.36 J kg(-1) m(-1). Both these values were not significantly higher than the energy cost in untrained nonhandicapped children of the same age. There was a U-shaped dependence of c on increased speed of walking. The minimum was about 3.6 km h(-1) in both groups of handicapped children, which was similar to that for non-handicapped subjects. It is concluded that in visually handicapped children the energy cost of walking, and thus adaptation to walking, is the same as in the healthy children. The visually handicapped individuals show a 'normal' response to exercise, to which they are adapted, with increases in both cardiovascular and muscular fitness.

Energy cost of treadmill walking

BACKGROUND

The purpose of this study was to determine if energy cost of walking (VO2) could be accurately predicted with the simple models which analyze relationship oxygen uptake-speed of walking. A model to predict energy cost of treadmill walking was published firstly 29 years ago.

METHODS

Employing the new modification of this model from 1986 to analyze VO2-speed of walking relationship leads to the elaboration of a simple linear model, two-compartment linear model, polynomial model of second order and monoexponential model of the metabolic cost of treadmill walking. To verify and compare these models 87 males, age ranged from 19 to 62 years, were evaluated on a motor driven treadmill. They walked at 0% grade at various velocities ranged from 3 to 12 km.h-1.

RESULTS

The linear model has in range of intensities 3-12 km.h-1 a form of VO2.kg-1 (ml.kg-1.min-1) = 5.228*v (km.h-1)-11.158, r = 0.812, S(EE) = 4.16 ml.kg-1.min-1. The two-compartment linear model has in range of intensities of 3-7 km.h-1 a form of VO2.kg-1 = 3.207*v(km.h-1)-1.777, r = 0.932, and S(EE) = 1.5. In the range of 7.1-12 km.VO2.kg-1 = 7.120*v-29.168, r = 0.901, S(EE) = 3.78. In the range of intensities from 3 to 12 km.h-1 a polynomial model was found in the form VO2.kg-1 = 4.501-0.108*v + 0.379*v2, r = 0.891, S(EE) = 4.43, and the exponential model had a form VO2.kg-1 = 4.360*exp(0.223*v), r = 0.861, S(EE) = 6.84. All these correlation coefficients were highly significant (p < 0.001 in all cases).

CONCLUSIONS

It was concluded that when applied to adult population, the models provide reasonable estimate of the actual requirement for treadmill walking provided the subjects in a oxygen uptake steady-state. As other researches for VO2/step we have found U-shaped curves of coefficient energy cost of walking. The minimum was at speed about 4 km.h-1. This finding support the speculation that does exists the "optimal" speed of moving which reflects the minimal energy expenditure during the walking.

Physiological profile of best Czech male and female young triathletes

To characterize the physiological profile of top young triathletes, 13 top female (mean age = 17.1 +/- 1.4 years, body mass = 58.8 +/- 4.7 kg, body height = 168.4 +/- 2.0 cm and body fat = 10.4 +/- 2.6%) and 23 top male triathletes (age = 17.7 +/- 2.2 years, mass = 66.7 +/- 7.1 kg, height = 176.5 +/- 5.1 cm and fat 8.2 +/- 2.3%) were evaluated by means of an incremental exercise (increment was 1 km.h-1, and exercise starting at 11 km.h-1 in females and 13 km.h-1 in males) on a treadmill with 5% inclination. Mean VO2max was 67.9 +/- 5.9 ml.kg-1 min-1 in boys and 56.1 +/- 2.4 ml.kg-1.min-1 in girls. mean value of maximal running speed was 18.6 +/- 1.2 km.h-1 in mean and 15.4 +/- 0.6 km.h-1 in females and LAmax was 12.5 +/- 2.3 mmol.l-1 in boys and 12.6 +/- 1.2 mmol.l-1 in girls. The selected functional variables at ventilatory threshold (VT) level in boys and girls corresponded to VO2max.kg-1 56.0 +/- 5.4 and 46.6 +/- 2.6 ml.kg-1.min-1, respectively, %VO2max.kg-1 at VT 82.4 +/- 2.1 and 83.1 +/- 1.7%, respectively, speed of running 15.2 +/- 1.4 and 12.7 +/- 0.7 km.h-1, respectively, %Vmax at VT 81.8 +/- 2.6 and 82.3 +/- 1.6%, respectively and the coefficient of energy cost of running c was 3.74 +/- 0.42 and 3.71 +/- 0.39 J.kg-1.m-1, respectively. A comparison of the functional profiles of these triathletes with elite young athletes from the sports of swimming (age 17.5 +/- 2.0 and 17.2 +/- 1.7 years, respectively, VO2max 61.6 +/- 3.6 and 52.1 +/- 3.6 ml.kg-1. min-1, respectively, Vmax 17.5 +/- 0.8 and 15.0 +/- 0.9 km.h-1, respectively, LAmax 11.1 +/- 3.2 and 11.8 +/- 3.3 mmol.l-1, respectively) cycling (17.7 +/- 1.8-17.0 +/- 1.7 years; 65.4 +/- 5.1-55.1 +/- 2.4 ml.kg-1. min-1, 18.2 +/- 0.7-15.2 +/- 0.8 km.h-1; 13.3 +/- 3.5-12.9 +/- 3.7 mmol.l-1) and middle-distance running (17.8 +/- 1.9-17.2 +/- 2.1 years; 66.8 +/- 4.7-57.3 +/- 2.6 ml.kg-1.min-1, 19.1 +/- 0.9-16.1 +/- 0.9 km.h-1; 13.1 +/- 2.6-13.7 +/- 3.0 mmol.l-1) showed the physiological characteristics of triathletes to be similar to those of middle-distance runners. According to our results and according to the data from the literature we can conclude that physiological predispositions for success in international triathlon may be as follows in boys and girls: VO2max.kg-1 higher than 65 and 60 ml.kg-1 min-1, respectively, Vmax (5%) higher than 18 and 16 km.h-1, respectively, LAmax higher than 12 and 11 mmol.l-1, respectively, running speed at "anaerobic threshold" higher than 15.0 and 13 km.h-1, respectively, %VO2max at "anaerobic threshold" level higher than 82.5% in both sexes, and the coefficient of energy cost of running lower than 3.75 and 3.73 J.kg-1.m-1, respectively. As in other sports events of an endurance native, these data are not the sole predictor of racing success. Nevertheless these standards are necessary but not sufficient conditions for success in triathlon. These data play a decisive role in the selection of talent for the triathlon.

[A simple method of evaluating physical fitness by means of walking]

BACKGROUND

Walking is at present the most frequently used means for purposes of rehabilitation as well as for maintenance or promotion of physical fitness. Recently we encounter with increasing frequency the use of walking as a diagnostic method for assessment of physical fitness under field conditions. The basis are motor tests of 1000 to 2000 m. The purpose of the submitted study was to prepare tables for the evaluation of the fitness level, using the 2000 m walking test and our standards of fitness.

METHODS AND RESULTS

The basis of the majority of evaluations of the fitness level based on the motor test are relations between the intensity of motor activity and the maximal oxygen consumption. Using general relations between the average walking speed in the 2000 m test and the maximal oxygen consumption assessed on a treadmill in non-trained healthy men and women and base on our population standards (VO2max.kg-1) tables were elaborated. The fitness level is evaluated using the average walking speed in the 2000 m test and the appropriate maximal oxygen consumption. The tables have three grades and make it possible to evaluate men and women aged 14-65 years.

CONCLUSIONS

The average speed in the 2000 m walking test makes it possible to evaluate by means of tables the physical fitness level in non-trained healthy subjects, provided the walking style is not of the racing type. The error of the estimate of physical fitness is about 15%.

Verification of the heart rate threshold

Among the methods for determining anaerobic threshold (AT), the heart rate (HR) method seems to be the simplest. On the other hand, many conflicting results from comparing this method with others have been presented over the last 10 years. Therefore, the aim of this study was to compare the heart rate threshold (HRT) with the lactate turn point (LTP)-"second" break point of dependence of lactate (LA) to power output, ventilatory threshold (VT) and threshold determined by electromyography (EMGAT), all determined by the same exercise test and evaluated by the same computer algorithm. A group of 24 female students [mean age 20.5 (SD 1.6) years, maximal oxygen consumption 48.8 (SD 4.7) ml.kg-1.min-1] performed an incremental exercise test on a cycle ergometer (modified Conconi test) starting with an initial power output (PO) of 40 W with intensity increments of 10 W.min-1 until the subjects were exhausted. The HRT, LTP and EMGAT determination was done by computer-aided break-point regression analysis from dependence of functional measures on PO. The same computer algorithm was used for VT determination from the relationship between ventilation (V) and oxygen uptake (VO2) or carbon dioxide output (VCO2).(ABSTRACT TRUNCATED AT 250 WORDS)

[Conversion of load intensity from a pedalling ergometer to a walking treadmill in patients with ischemic heart disease]

BACKGROUND

For requirements of physical rehabilitation it is important to know the "safe" load intensity: this can be assessed reliably among others on a pedalling ergometer. The purpose of the present work was to reveal conversion relations between laboratory loads on a pedalling ergometer and the load of walking which is the most natural physical activity recommended for keeping fit and for rehabilitation, incl. rehabilitation of patients with ischaemic heart disease, after cardiosurgery etc.

METHODS AND RESULTS

In order to obtain conversion relations between the load intensity on a pedalling ergometer and walking on a treadmill, on the same day a group of 40 men (mean age 51.0 +/- 5.0 years, body weight 83.7 +/- 9.9 kg, height 175.3 +/- 5.8 cm and mean body fat 18.6 +/- 4.0%) were subjected to both types of exercise. All patients were for varying periods after a myocardial infarction or revascularization surgery (aortocoronary bypass type) and had different load tolerances. From the functional aspect they belonged into group NYHA I: On a single day thy were subjected to examination on a pedalling ergometer with a load of 0.75, 1.25, 1.75 W.kg-1 and on a treadmill, 0 gradient, at a rate of 3.5 and 7 km.h-1. Assuming a linear relationship between load intensity and oxygen consumption a simple relationship is found between the rate of walking in km.hour-1 and the pedalling intensity P/W.kg-1, i.e. v = 3.051 x P + 1.361. This relationship can be used for conversion of load intensities from the bicycle to walking on a treadmill or on even ground up to intensities of a pedalling load 1.75 W.kg-1 and walking at a rate of 7 km.h-1 with an error less than 10%.

CONCLUSIONS

The authors elaborated a mathematically expressed general relation for conversion of the load intensity on a pedalling ergometer to walking on even ground.

Heart rate threshold related to lactate turn point and steady-state exercise on a cycle ergometer

The aim of this study was to investigate heart rate threshold (HRT) related exercise intensities by means of two endurance cycle ergometer tests using blood lactate concentration [La], pulmonary ventilation (VE), oxygen uptake (VO2), heart rate (HR) and electromyogram (EMG) activity of working muscle. Firstly, 16 healthy female students [age, 21.4 (SD 2.8) years; height, 167.1 (SD 5.1) cm; body mass 62.7 (SD 7.1) kg] performed an incremental exercise test (10 W each minute) on an electrically braked cycle ergometer until they felt exhausted. The HRT and lactate turn point (LTP) were assessed by means of computer-aided linear regression break point analysis from the relationship of HR or [La] to power output. No significant difference was found between HRT and LTP for all the variables measured. Secondly, two endurance tests (ET) of 20 min duration were performed by 7 subjects. The first (ET I) was performed at an exercise intensity which was about 10% lower than the power output at HRT [61.2 (SD 3.1)% maximal oxygen uptake (VO2max)], the second (ET II) at an exercise intensity about 10% higher than the power output at HRT [79.2 (SD 3.4) % VO2max]. The parameters measured showed a clear steady state in ET I. All mean values were lower than values at HRT [power, 138.7 (SD 18.9) W; HR, 172.1 (SD 4.7) beats.min-1; VO2, 2.2 (SD 0.3) l.min-1; VE, 54.0 (SD 9.1) l.min-1; [La], 3.7 (SD 1.1) mmol.l-1; EMG, 81.1 (SD 24.0) microV] except HR which was the same.(ABSTRACT TRUNCATED AT 250 WORDS)

A simple method for estimating aerobic fitness

Physical activity is an integral part of everyday life. In order to evaluate physical fitness, there is a need for simple measures of which motor performance testing is one. The frequently used method for evaluating aerobic fitness, proposed by Cooper (1968), is based on measurements of an American population, and may involve estimating inaccuracy for aerobic fitness when used under European conditions. In this paper, tables for the estimation of aerobic fitness and physical performance are derived from a European sample (229 males, 153 females), incorporating general relations between velocity of movement and energy required for this activity expressed indirectly by oxygen consumption. The basic element of this evaluation under field conditions is the mean velocity of motion on a 2000 m track. The tables have been prepared for males and females aged 14-65 years, making it possible to estimate 'poor', 'good', and 'excellent' levels of aerobic fitness and physical performance. The error of assessment of maximal oxygen uptake and the physical fitness level varies by about 8%.

Energy cost of running in young and adult female athletes

Maximal oxygen uptake (VO2 max.kg-1) and energy cost of running were determined on the treadmill in groups of differently trained young and adult athletes. The VO2 max.kg-1 was in all cases higher in adults than in young athletes. These differences were significant (p < 0.05) in long-distance runners (n = 12, mean age = 24.2 +/- 2.2 vs 17.3 +/- 0.9 yrs, mean VO2 max.kg-1 = 66.9 +/- 4.2 vs 58.2 +/- 4.3 ml.min-1.kg-1), and in middle-distance runners (10, 22.9 +/- 2.8 vs 16, 16.6 +/- 0.8, 62.3 +/- 3.7 vs 56.1 +/- 2.8); in canoeists these differences were non-significant (7, 21.1 +/- 2.1 vs 16.0 +/- 2.3 vs 8, 48.2 +/- 2.6). Values of energy cost of running--coefficients of energy demand of running c, which indicates how much energy is required to transfer 1 kg of body mass on a distance of 1 m--were lower in adult athletes than in young athletes. These differences were significant (p < 0.05) only in long-distance runners (3.69 +/- 0.15 vs 3.84 +/- 0.14 J.kg-1.m-1). In middle-distance runners (3.67 +/- 0.19 vs 3.76 +/- 0.18), and in canoeists (3.84 +/- 0.14 vs 3.86 +/- 0.18) these differences were non-significant. It is concluded that the differences in energy cost of running between trained adult and young female athletes are probably associated with differences in adaptation to the running, and with the technique of movement. Differences in running speed (sports performance) between adult and young athletes are associated with differences in VO2 max.kg-1 and c.

Ventilatory threshold and work efficiency during exercise on cycle and paddling ergometers in young female kayakists

The aim of this study was to assess the effects of increasing specific (paddling ergometer) and non-specific (cycle ergometer) exercise on parameters relating to the ventilatory threshold (Th(vent)) and work efficiency in 11 young female flat-water kayakists. When these trained subjects were tested using non-specific workloads, their oxygen uptake (VO2) values at Th(vent), as a percentage of VO2max (%VO2max), were close to those of untrained subjects [74.2 (5.6) % VO2max, mean (SD)]. However, when we tested the same subjects using specific exercise, we recorded values typical of highly trained athletes [84.8 (4.7) % VO2max). For the non-specific exercise on the cycle ergometer, we recorded work efficiency values close to those of untrained subjects [22.3 (2.5) %]; however, for the specific exercise on the paddling ergometer, we recorded much lower values [13.4 (3.0) %] both at the level of Th(vent). The work efficiency at two warm-up submaximal exercise loads on the paddling ergometer was non-significantly lower than values at Th(vent) [12.3 (2.8) % and 12.9 (2.9) % respectively]. Significant correlations were found between maximal-performance VO2 (ml.kg-1.min-1) and performance at Th(vent) during paddling and race performance (0.623, 0.630 and 0.648 respectively, all P < 0.05). Because the results of both specific and non-specific submaximal exercise tests are different, we suggest caution in the interpretation of physiological variables that may be sensitive to training status. The evaluation of Th(vent) and work efficiency as supplementary parameters during laboratory studies enables the determination of the effectiveness of the training process and the specific adaptation of the subjects.

[Energy requirements for walking]

The energy requirement of walking, expressed indirectly by the oxygen consumption per kg body weight was assessed during different speeds of walking on a treadmill within the range of 3-12 km.h-1 in 87 untrained healthy men aged 17.5 to 60 years. The dependence of VO2.kg-1 on the speed of walking is non-linear in the mentioned range. Most suitable is the two-component linear model which in the range of 3-7 km.h-1 has the shape of VO2.kg-1 (ml.kg-1.min-1 = 3.207.v/km.h-1 - 1.777, r = 0.932 with a mean predicting error of 1.5.ml.kg-1.min-1, in the range of load of 7-12 km.h-1 VO2 = 7.120.v - 29.168, r = 0.941 with a error predicting of 3.73. The polynomic model of relations in the entire range of 3-12 km.h-1 is VO2 = 4.503 - 0.108.v + 0.379.v2, r = 0.922 with a predicting error of 4.43 ml.kg-1.min-1, and finally the exponential model has the shape VO2 = 4.360 exp (0.223.v), r = 0.861 with a mean predicting error of 6.84 ml.kg-1.min-1 in the entire range of load intensities. The justification to express the relationship between the oxygen consumption and the rate of walking by a two-component linear model as well as by non-linear models is confirmed also by the high correlation coefficient (p < 0.001 in all instances). The error of assessment of VO2.kg-1 from the speed of walking is 10% or less in all models. The mentioned models, in particular the linear one, can be used for evaluation of physical activities involving walking outdoors.

Ventilatory threshold in young and adult female athletes

We determined in a laboratory on the treadmill the ventilatory threshold in relatively similarly trained groups of young and adult female athletes (14 adult long-distance runners mean age = 24.3 +/- 2.3 yrs; mean VO2max.kg-1 = 66.9 +/- 4.2 ml.kg-1.min-1; 11 adolescents 16.3 +/- 0.9; 58.4 +/- 4.4; 10 adult middle distance runners mean age = 22.9 +/- 2.9 yrs and VO2max.kg-1 = 62.3 +/- 3.7 ml/kg-1/min-1; 16 juniors 16.6 +/- 0.8 and 15.1 +/- 2.8; 7 adult canoeists 21.1 +/- 2.1 and 50.0 +/- 2.9; 8 adolescents 16.0 +/- 0.9 and 48.2 +/- 2.6). Maximal blood lactate concentration was found in all groups slightly lower in young athletes than in adults (in long-distance runners 10.9 +/- 2.6 vs 11.4 +/- 3.2 mmol.l-1; in middle-distance runners 12.4 +/- 2.3 vs 12.7 +/- 2.9; in canoeists 11.8 +/- 3.3 vs 12.1 +/- 3.6). The differences in maximal blood lactate concentration were nonsignificant in all groups. We did not find any significant differences in percentage of maximal aerobic power on the ventilatory threshold level. In long-distance runners the mean value of % VO2max at AT was 85.1 +/- 3.8% for adults and 84.9 +/- 2.7% for adolescents, in middle-distance runners 82.9 +/- 2.1% and 82.6 +/- 3.2%, respectively, and in adult canoeists 79.9 +/- 2.6%, and in juniors 79.4 +/- 3.0%. According to these results we can conclude that the physical activity and/or level of physical fitness seem to be main factors which may influence the values of % VO2max at VT during the growth.

Ventilatory threshold and work efficiency during exercise on a cycle and rowing ergometer

The purpose of this investigation was to determine the effects of increasing specific (rowing ergometer) and non-specific (cycle ergometer) workloads on parameters relating to the ventilatory threshold (Tvent) and work efficiency. When highly trained male rowers were tested using non-specific workloads, their %VO2 max values at Tvent were close to those characteristic of untrained subjects (74.6 +/- 6.2% VO2 max). However, when we tested the same subjects using specific workloads, we recorded values typical of highly trained athletes (85.0 +/- 4.4% VO2 max). For the non-specific exercise on the cycle ergometer, we recorded work efficiency values close to those of untrained subjects (22.8 +/- 2.1%); however, for the specific exercise on the rowing ergometer, we recorded much lower values (16.4 +/- 3.1%). Because of the results of the non-specific submaximal exercise tests, we suggest caution in the interpretation of physiological variables that may be sensitive to training status. The evaluation of Tvent and work efficiency as supplementary parameters during laboratory studies will enable researchers to ascertain the effectiveness of the training process used, as well as indicating the specificity of the loading apparatus.

[Use of walking in the evaluation of aerobic fitness]

The reliability and validity of assessment of the maximal oxygen consumption as a criterion of aerobic fitness by the 2000 m walking test was established in 38 students of the military secondary school (mean age 17.8 +/- 0.4 years). The reliability of the 2000 m walking test is very high, during repeated estimations in the course of one week we find a correlation coefficient of r = 0.82 (p < 0.001). There is also a close correlation of 2000 m walking time and 2000 m running time (r = 0.67, p < 0.001). A group of 18 students selected at random from the above group was examined in the laboratory on a treadmill up to vita maxima. A close correlation was found between the results during walking and the maximal oxygen consumption (VO2max.kg-1) (r = -0.59 and -0.60) and also the 2000 m running time and VO2max.kg-1 (r = 0.59), p < 0.01 in all instances. The standard error of the mean of the maximal oxygen consumption estimate from the 2000 m walk is 3.44 ml.kg-1 x min-1 (5.7%) and from the running time of the same distance 3.49 ml.kg-1 x min-1 (5.8%). These results justify the conclusion that the 2000 m rapid walking test (normal style) is a simple alternative way for estimating the maximal oxygen consumption and thus also for evaluating the level of aerobic fitness with an accuracy which matches that, when running is used for the test.

Assessment of predispositions for endurance running from field tests

Field tests of speed and endurance may be used to evaluate the probability of success and to create efficient training strategies for sports. Currently, both invasive and non-invasive methods are used for this purpose. While invasive methods cause some discomfort to subjects, non-invasive methods may employ practices associated with the sport itself. One such method employs the linear relationship between exercise intensity or running speed and distance covered running at that speed represented on a semi-logarithmic scale. The separation of endurance runners into three different groups can be confirmed by different values for the slope coefficient (b) of this linear relation. According to findings among top Czechoslovak endurance runners, supplemented by the data of other authors, the values of coefficient b in middle-distance runners are in the range -2.166 to -1.700, in long-distance runners -1.520 to -1.050 and in marathon runners -0.836 to -0.436. Similarly, a separation of young endurance runners into groups of middle-distance and long-distance runners must be within the range -2.158 to -1.800 and for young long-distance runners -1.700 to -1.300. Based on these findings, the optimum competitive distance for adult athletes can be established in relation to current training status. In young athletes, it is possible to select gifted runners with predispositions for middle-distance and long-distance running. For both groups of athletes, more efficient training methods can be selected to optimize their predispositions for maximal performance.

[Conversion of the intensity of loading from the bicycle ergometer to a treadmill and to field training in women]

When evaluating the standard of functional fitness, state of training or work capacity of subjects, when diagnosing loads, when assessing training of healthy subjects and sportsmen and locomotor rehabilitation of patients usually two types of ergometers are used--a pedalling ergometer and a treadmill. Each of these ergometers has its specific properties, advantages and shortcomings. For the practical use of results of functional examination in the laboratory, where the majority of our diagnostic departments possesses only a pedalling ergometer it is necessary to convert the load intensity from the bicycle to a treadmill and to the field where physical training is usually implemented. Based on our measurements in groups women with different grades of training, differing as to age, it is possible to elaborate a general equation which relates the load intensity on the pedalling ergometer P/W.kg-1 and the speed of running on the treadmill with a zero gradient v/km.h-1 in the form v = 3,695.P-1,419. This relationship can be used with an error of cca 12% in the zone of submaximal load intensities (up to 90% of the maximal load intensity). For P lower than 3.9 W.kg-1 this equation can be used for direct conversion to flat ground. For higher load intensities there is the relationship v = 3,156.P + 0.446 which has the same error of 12% as for even ground.

[Energy requirements in women during pedalling on a bicycle ergometer]

The bicycle ergometer is the most frequently used equipment for loading tests for the purpose of functional diagnosis and for the purpose of locomotor rehabilitation. The energy required to meet this locomotor activity is within a wide range of load intensities which depends linearily on the intensity of pedalling. The steepness of this linear relationship which characterizes the degree of adaptation of the organism to this type of locomotor activity is the smaller the more the investigated subjects are adapted to the load. In general it depends on the degree of training, age, sex, strength, pedalling frequency, on the load protocol and on the biomechanical conditions during pedalling (e.g. the height of the saddle). Based on our measurements in a group of untrained women of different age and in trained women of different age it can be demonstrated that all individual relations between energy characterized by means of VO2 and the intensity of the load - P is within the zone where the upper borderline is formed by the equation VO2(ml) = 11.00.P (W) + 403 and the lower borderline by VO2(ml) = 9.90.P (W) + 252. The basic relationship, independent on the degree of training, age and strength, valid in the zone of pedalling frequencies of 60-80 rot. min-1 and in the zone of load intensities of 75-325 W has the shape of VO2(ml) = 10.60.P(W) + 269. The maximum error of assessment of VO2 by means of the load intensity is 9% or less.

Exercise intensity conversion from a bicycle ergometer to a treadmill

In the evaluation of the general functional fitness and/or work capacity of subjects for the purpose of exercise diagnostics, physical fitness enhancement in untrained healthy subjects or sportsmen and exercise rehabilitation of patients, two types of ergometers are generally used: a bicycle ergometer and a treadmill. To facilitate the conversion of results of functional examinations made in the laboratory to field conditions, where, as a rule, physical activity is performed, the intensity of exercise assessed on the bicycle ergometer must be converted to that on a treadmill and vice versa. Measurements on a bicycle ergometer and treadmill in differently trained groups of men can be supplemented with data from the literature to develop a general equation which relates exercise intensity on the bicycle ergometer P (W.kg-1) and running speed on the treadmill v (km.h-1) as v = 3.544.P +/- 0.625. In the submaximal range of exercise intensities (20-80% of maximal aerobic power) this relationship is independent on the training status, age, body weight, strength and speed capacity of the subjects examined. The above equation may be used in the submaximal exercise intensity range with a maximum error of about 12% or less.

Ventilatory threshold and work efficiency on a bicycle and paddling ergometer in top canoeists

The purpose of this investigation was to determine the effect of increasing specific (paddling ergometer) and non-specific (bicycle ergometer) work load on the parameters at the ventilatory threshold (VT) and on work efficiency (WE) during increasing exercise ergometry. When highly trained male canoeists were given an unspecific exercise load, the values of %VO2max at VT were close to the values characteristic for an untrained population (72.3 +/- 5.3% VO2max). When the same subjects were given a specific work load, they produced values typical for highly trained athletes (83.4 +/- 2.5% VO2max). Non-specific exercise produced WE values close to those of untrained subjects on the bicycle ergometer (23.3 +/- 2.1%), and when loading is specific, the groups of working muscles are smaller, producing lower WE values (14.7 +/- 3.5%). It was concluded that the responses to submaximal exercise intensities in the case of nonspecific loading suggests caution in the interpretation of physiological variables which may be sensitive to training status. The assessment of VT and WE as supplementary characteristics during laboratory measurements, enables us, along with other parameters, to ascertain not only the effectiveness of the training process used, but also the specificity of a loading apparatus.

[Anaerobic "all-out" stress tests: selection of the type and duration of stress]

In the diagnosis of prerequisite conditions for short-term highly intensive activity, performed under conditions of oxygen deficit anaerobic loading tests are used. Contrary to tests of constant performance, "all-out" tests follow up changes of performance in the course of time, i. e. they record the maximal anaerobic performance as well as the decline of performance in the course of the test. In a group of 17 subjects three types of loads were compared (bicycle ergometry, a test repeated jumps and running) and two periods of anaerobic tests--45 s and 120 s. The results achieved in different tests--total work, maximum performance, decline of performance, post-load lactate concentration in blood--differed depending on the type of load and duration of the test. Correlation analysis did not reveal a close relationship between the results of different anaerobic tests, there was however a relationship between the maximum performance and the total work at the level of general physical fitness. The longer variant of the test--120 s--did not prove more suitable, neither from the aspect of the assumed markedly higher lactate cumulation in blood nor from the aspect of maximum performance, as compared with the 45 s test. A close relationship was revealed between the results of the 45 s and 120 s jumping and running test but not between the results of bicycle ergometry. The post-load lactate concentration cannot be considered a highly reliable indicator of the level of the anaerobic energy metabolism in the working muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

[A simple method for estimating the level of physical fitness]

Physical activity is becoming an integral part of everyday life. In order to modify and control this activity we need simple and readily available criteria for the control of physical fitness. One of the possible approaches how to resolve this problem is to use motor tests. The most frequently used method for evaluation of physical fitness proposed by Cooper, based on measurement in the American population may involve, when used under our conditions, inaccuracy of estimates of physical fitness and be associated with some difficulties regarding the 12-minute period of the test. The author submits therefore tables for the estimation of physical fitness elaborated with regard to our population standards and general relations between the velocity of movement and energy required for this activity expressed indirectly by oxygen consumption. The basic element of evaluation is the velocity of movement of a 2000 to 3000 m track. The tables were prepared for men and women aged 14-65 years and make it possible to estimate below-average, average and above-average levels of physical fitness. The error of assessment of VO2 max and thus also of the estimate of physical fitness level varies round 15%.

[A simple method of determining the intensity and duration of physical exertion]

Determination of the intensity and duration of physical activity with respect to the individual condition of the organism is essential for the effective control of physical training. One of the possible methods of establishing those quantities is making use of the dependence of intensity on the duration of physical exercise. Using semi-logarithmic coordinates (the intensity of exercise is given in the decomal system, the period of time in logarithms) this dependence is of the linear type. The straight line constructed from the limit (highest) intensities of exertion and the relevant times of exercise in any given individual, which must take into account that individual's state of health and fitness, cuts the plane of all conceivable combination of intensity-duration, into two semi-planes. All the actual combinations of those variables exploitable for training purposes are found in the semi-plane situated to the left of this line. With regard to the purpose of physical training it is then possible simply to choose the required intensity of exercise and to find the respective zone of the duration of this exercise, or it is possible to choose the duration of physical exercise and to read from the graph the respective zone of intensity. This intensity can be put either in terms of the speed of movement or, indirectly, in terms of the heart rate. This method of determining the intensity and duration of physical exercise can be used for all activities of the cyclic type, e.g. running, cycling, swimming and so on.