An Alternative Prediction Equation for Evaluation of Six-Minute Walk Distance in Stable Coronary Artery Disease Patients.

Background: As cardio-vascular diseases are the leading cause of death worldwide, establishing measures to improve cardiovascular health is of crucial importance. Exercise plays an essential role in cardiac rehabilitation of patients with coronary artery disease (CAD), in whom an evaluation of the cardiorespiratory fitness (CRF) is necessary. CRF of CAD patients could be assessed using 6-min walk test (6MWT), and the results interpreted by using Enright-Sherill prediction equation which has mainly been designed and evaluated for a healthy population. Hypothesizing that the Enright-Sherill prediction equation might not be best suited for CAD patients, our aim was to reevaluate this equation in CAD patients, and potentially establish a more accurate 6MWD prediction equation to be applied in these patients. Methods: 6MWD was measured in a cross-sectional study in 67 CAD patients (44 women) who were members of the Coronary club Ljubljana, Slovenia. In addition, the predicted 6MWD was calculated for men and women using Enright-Sherill gender specific regression equation. Multivariate regression analysis was used to obtain a new prediction equation, and the agreement between the measured and the predicted 6MWD analyzed using the repeated measures ANOVA. Results: Men achieved 451 ± 122 m and women 485 ± 69 m without significant differences between sexes (F = 0.022, p = 0.882) when adjusted for age, height, body mass, and waist circumference. When comparing the measured (473 ± 91 m) and the predicted (422 ± 57 m) values of 6MWD in CAD patients we found that the Enright-Sherill prediction equation significantly (F = 27.734, p < 0.001) underestimated the 6MWD by 52 ± 81 m. A significant regression equation was established [F (3,63) = 44.663, p < 0.001], with a R 2 of 0.680 where 6MWD equals 1,057 m-4.966 x age (years)-0.614 x WC (cm)-68.629 x NYHA class. Conclusion: The results of this study stress the importance of regular and actual walking ability testing in patients with stable CAD to obtain their CRF, rather than simply predicting it from regression equations obtained from non-representative or non-comparable samples. Our developed prediction equation warrants additional validation and may represent a good substitute for currently used predictions obtained from a healthy population.

Quadriceps strength asymmetry as predictor of ankle sprain in male volleyball players.

BACKGROUND: Ankle sprain is the most common acute time-loss injury in volleyball and occurs mainly during landing from a jump. Therefore, we have evaluated the role of quadriceps strength and countermovement jump height on ankle sprain occurrence, as these intrinsic modifiable risk factors were not yet evaluated. We have also hypothesized that presence of quadriceps strength asymmetry could be a possible risk factor for ankle sprains in male volleyball players. METHODS: This was a prospective cohort study. Male volleyball players (N.=99) from Slovenian national league participated in the study. Before the start of the season, all participants completed a preseason questionnaire and underwent evaluation of vertical jump performance and bilateral isokinetic strength of the quadriceps (Q) and hamstrings (H). During the subsequent season the players reported acute time loss injuries because of ankle sprain through a weekly questionnaire. RESULTS: We have registered 19 ankle sprains during the season. Overall ankle sprain incidence was 0.41±0.24 per 1000 h. Previous ankle sprain (Odds Ratio: 0.86; 95% CI: 0.25-2.89, P=0.802) and jump height (1.05; 95% CI: 0.94-1.19, P=0.393) were not significant risk factors, while Q strength asymmetry was a significant predictor of an ankle sprain (Odds Ratio: 0.956; 95% CI: 0.919-0.995, P=0.026). Compared with the uninjured players, the injured players had higher right concentric Q strength, higher Q strength asymmetry, and lower concentric right H-Q strength ratio (all P<0.03). CONCLUSIONS: Our results suggest that excessive concentric strength of the right Q, which leads to low H-Q strength ratio, and high bilateral Q strength asymmetry in favor of the right side, could be associated with increased risk of ankle sprains in male volleyball.

Six-Minute Walk Distance in Breast Cancer Survivors-A Systematic Review with Meta-Analysis.

The six-minute walk test (6MWT) is a widely used test for the indirect measurement of cardiorespiratory fitness in various cancer populations. Although the 6MWT is a simple test, there are no normative values for breast cancer survivors (BCS) or comparisons of results with healthy counterparts. A systematic review with a meta-analysis was carried out, which included studies from 2007 to 2020. Ninety-one studies were found, 21 of which were included in the quantitative synthesis. Among them were 9 randomized controlled trials (RCT), 8 prospective cohort studies and 4 cross-sectional studies. A total of 1084 BCS were included. Our results revealed that healthy subjects (n = 878) covered a significantly greater distance than BCS during the 6MWT (589.9 m vs. 477.4 m, p < 0.001), and the results of the meta-regression analysis showed that the 6MWD was predicted by the participants' BMI (p < 0.001), but not by their age (p = 0.070). After adjustment for BMI, the healthy subjects also covered greater distances than the BCS (103 m; p < 0.001). The normative values of 6MWT were presented for BCS. Besides, 6MWT distances distinguish between their healthy counterparts, therefore, the 6MWT distance is a relevant parameter for the assessment and monitoring of cardiorespiratory fitness in medical and exercise interventions for BCS.

Risk for eating disorders and body composition among adolescent female and male athletes and non-athlete controls.

Purpose The objective of this research was to investigate the risk for eating disorders (EDs) and compare body composition in participants with and without risk in adolescent Slovenian athletes and aged matched controls. Methods A total of 583 randomly selected adolescents, aged from 15 to 17 years, completed a sick, control, one stone, fat, food (SCOFF) questionnaire for detecting risk for EDs. Weight and body composition were measured using a bioelectrical impedance machine. Based on the data body mass index (BMI), percentiles were calculated. Results Overall, 37.7% of athletes and 39.8% of controls were classified as at risk for EDs. Girls showed a significantly higher frequency of risk than boys, 1:3.5. A higher percentage of underweight boys was found in control group compared to the athletes, but the difference was not significant in the subsample of girls. Differences in body composition show that the at-risk group had significantly higher values in BMI percentiles (p < 0.001) and percentages of fat mass (p < 0.001) and lower values in percentage of muscle mass (p < 0.01) and fat-free mass. Conclusions These finding demonstrate that the gap in risk for EDs between males and females is becoming smaller and stresses to consider specific parameters of body composition as being important when identifying at-risk groups for EDs.

Isokinetic knee strength qualities as predictors of jumping performance in high-level volleyball athletes: multiple regression approach.

BACKGROUND: Previous investigations noted potential importance of isokinetic strength in rapid muscular performances, such as jumping. This study aimed to identify the influence of isokinetic-knee-strength on specific jumping performance in volleyball. The secondary aim of the study was to evaluate reliability and validity of the two volleyball-specific jumping tests. METHODS: The sample comprised 67 female (21.96±3.79 years; 68.26±8.52 kg; 174.43±6.85 cm) and 99 male (23.62±5.27 years; 84.83±10.37 kg; 189.01±7.21 cm) high- volleyball players who competed in 1st and 2nd National Division. Subjects were randomly divided into validation (N.=55 and 33 for males and females, respectively) and cross-validation subsamples (N.=54 and 34 for males and females, respectively). Set of predictors included isokinetic tests, to evaluate the eccentric and concentric strength capacities of the knee extensors, and flexors for dominant and non-dominant leg. The main outcome measure for the isokinetic testing was peak torque (PT) which was later normalized for body mass and expressed as PT/Kg. Block-jump and spike-jump performances were measured over three trials, and observed as criteria. Forward stepwise multiple regressions were calculated for validation subsamples and then cross-validated. Cross validation included correlations between and t-test differences between observed and predicted scores; and Bland Altman graphics. RESULTS: Jumping tests were found to be reliable (spike jump: ICC of 0.79 and 0.86; block-jump: ICC of 0.86 and 0.90; for males and females, respectively), and their validity was confirmed by significant t-test differences between 1st vs. 2nd division players. Isokinetic variables were found to be significant predictors of jumping performance in females, but not among males. In females, the isokinetic-knee measures were shown to be stronger and more valid predictors of the block-jump (42% and 64% of the explained variance for validation and cross-validation subsample, respectively) than that of the spike-jump (39% and 34% of the explained variance for validation and cross-validation subsample, respectively). Differences between prediction models calculated for males and females are mostly explained by gender-specific biomechanics of jumping. CONCLUSIONS: Study defined importance of knee-isokinetic-strength in volleyball jumping performance in female athletes. Further studies should evaluate association between ankle-isokinetic-strength and volleyball-specific jumping performances. Results reinforce the need for the cross-validation of the prediction-models in sport and exercise sciences.

Risk Factors for Eating Disorders among Male Adolescent Athletes.

OBJECTIVE: Eating disorders (ED) are an important and increasing problem in adolescents. The objective of this study was to examine the risk factors and the prevalence of risk for ED among male adolescent elite athletes and nonathletic controls. Differences between male athletes competing in aerobic, anaerobic and aerobic-anaerobic sports were examined as well. METHODS: This was a cross-sectional epidemiological study. A cross-sectional questionnaire survey and anthropometric measurements were conducted on 351 adolescents (athletes n = 228; controls n = 123). All participants were aged 15-17 at the time of measuring. Risk for ED was determined using a SCOFF questionnaire. RESULTS: The overall prevalence of the risk for ED in male adolescents was 24.8%, with no significant differences among athletes and controls or different subgroups of athletes (p>0.05), although the highest prevalence (37.2%) was registered in aerobic subgroup of athletes. Higher number of attempts to lose weight was associated with increased risk of ED in each group (athletes and controls). Other predictors referred to lack of breakfast and body composition in aerobic subgroup of athletes and number of meals and training frequency in anaerobic subgroup. The most common reasons for dieting were improvement of sport results (19.6-44.2%) and better self-esteem (41.5%) in athletes and controls respectively. CONCLUSIONS: Participation in the competitive sport itself is not associated with the increased risk for ED. It seems that risk factors for ED for adolescent athletes competing in aerobic and anaerobic sports represent a subject that deserves consideration and further investigation in the future.

Vertical jump performance of professional male and female volleyball players: effects of playing position and competition level.

Vertical jump (VJ) performance is an important element for successful volleyball practice. The aims of the study were (a) to explore the overall VJ performance of elite volleyball players of both sexes, (b) to explore the differences in VJ performance among different competition levels and different playing positions, and (c) to evaluate the sex-related differences in the role of the arm swing and 3-step approach with arm swing on the jump height. We assessed the VJ capacity in 253 volleyball players (113 males and 140 females) from Slovenian first and second Volleyball Division. The height of squat jump (SJ), countermovement jump, block jump, and attack jump was tested using an Optojump system. We observed significant differences (p ≤ 0.05) in VJ height between different levels of play that were most pronounced in the SJ. Position-related differences in VJ performance were observed in male players between receivers and setters (p ≤ 0.05), whereas in females, VJ performance across different playing positions seems equal. Finally, we found that male players significantly better use the arm swing during VJ than females (p ≤ 0.05), whereas the use of eccentric part of the jump and approach before the spike to improve VJ performance seem to be equally mastered activity in both sexes. These results could assist coaches in the development of jumping performance in volleyball players. Furthermore, presented normative data for jump heights of elite male and female volleyball players could be useful in selection and profiling of young volleyball players.

Strength asymmetry of the shoulders in elite volleyball players.

CONTEXT: Volleyball players are reported to have shoulder strength imbalances. Previous authors have primarily investigated small samples of male players at a single skill level, without considering playing position, and with inconsistent findings. OBJECTIVE: To evaluate shoulder strength asymmetry and a history of shoulder injury in a large sample of professional volleyball players of both sexes across different playing positions and skill levels. DESIGN: Descriptive laboratory study. PATIENTS OR OTHER PARTICIPANTS: A sample of 183 volleyball players (99 men, 84 women). MAIN OUTCOME MEASURE(S): We assessed shoulder internal-rotator and external-rotator concentric strength at 60°/s using an isokinetic dynamometer and dominant-nondominant differences in shoulder strength and strength ratios using repeated-measures analyses of variance. Peak torque was normalized for body mass and external-rotation/internal-rotation concentric strength. RESULTS: Internal-rotation strength was asymmetric in favor of the dominant side in both sexes, regardless of previous shoulder injury status. Male volleyball players had a lower shoulder strength ratio on the dominant side, regardless of previous shoulder injury status. However, this finding was valid only when hand dominance was taken into account. Female volleyball players playing at a higher level (ie, first versus second division) were 3.43 times more likely to have an abnormal strength ratio. Playing position was not associated with an abnormal shoulder strength ratio or strength asymmetry. CONCLUSIONS: In male volleyball players, the external-rotation/internal-rotation strength ratio of the dominant shoulder was lower, regardless of playing position, skill level, or a previous shoulder injury. In female players, the ratio was less only in those at a higher skill level. Although speculative, these findings generally suggest that female volleyball players could have a lower risk of developing shoulder-related problems than male volleyball players. Isokinetic shoulder testing may reveal important information about the possible risk factors for shoulder injuries, so we recommend including it in the functional screening of volleyball players.

Bilateral concentric and eccentric isokinetic strength evaluation of quadriceps and hamstrings in basketball players.

The aim of the study was to investigate the existence of bilateral asymmetry in healthy basketball players of different age, as evidence suggest that it may be an age related phenomenon which develops over the years of training. Fifty healthy basketball players (26 males and 24 females) participated in the study. The quadriceps (Q) and the hamstring (H) were tested concentrically and eccentrically at 60 degrees/s. The main outcome measure was body weight normalized peak torque (PT/BW). We have also calculated different strength ratios as well as the bilateral strength differences. The main findings indicate that (1) bilateral strength asymmetry is noticeable in senior basketball players relating predominantly to the Q (2) some gender related strength differences were mainly associated with the concentric strength of Q and H (3) when corrected for weight and height, age related strength differences were relatively small and observed only with respect to H strength in males (4) superiority of eccentric over concentric strength values of Q and H was more pronounced in females than in males. Strength asymmetry in senior basketball players may be more attributable to the better neuromuscular control during vertical jumping than to the strength itself as there were no age related differences between cadets and senior players.

Vertical jumping tests in volleyball: reliability, validity, and playing-position specifics.

Vertical jumping is known to be important in volleyball, and jumping performance tests are frequently studied for their reliability and validity. However, most studies concerning jumping in volleyball have dealt with standard rather than sport-specific jumping procedures and tests. The aims of this study, therefore, were (a) to determine the reliability and factorial validity of 2 volleyball-specific jumping tests, the block jump (BJ) test and the attack jump (AJ) test, relative to 2 frequently used and systematically validated jumping tests, the countermovement jump test and the squat jump test and (b) to establish volleyball position-specific differences in the jumping tests and simple anthropometric indices (body height [BH], body weight, and body mass index [BMI]). The BJ was performed from a defensive volleyball position, with the hands positioned in front of the chest. During an AJ, the players used a 2- to 3-step approach and performed a drop jump with an arm swing followed by a quick vertical jump. A total of 95 high-level volleyball players (all men) participated in this study. The reliability of the jumping tests ranged from 0.97 to 0.99 for Cronbach's alpha coefficients, from 0.93 to 0.97 for interitem correlation coefficients and from 2.1 to 2.8 for coefficients of variation. The highest reliability was found for the specific jumping tests. The factor analysis extracted one significant component, and all of the tests were highly intercorrelated. The analysis of variance with post hoc analysis showed significant differences between 5 playing positions in some of the jumping tests. In general, receivers had a greater jumping capacity, followed by libero players. The differences in jumping capacities should be emphasized vis-a-vis differences in the anthropometric measures of players, where middle hitters had higher BH and body weight, followed by opposite hitters and receivers, with no differences in the BMI between positions.

Injuries in racket sports among Slovenian players.

On the sample of 83 top Slovenian athletes we have studied the frequency of injuries among table tennis, tennis and badminton players, types of injuries and severity of injuries--the latter based on data of players absences from training and/or competition processes. The most liable parts to injuries are shoulder girdle (17.27%), spine (16.55%) and ankle (15.83%), while foot (10.07%) and wrist (12.23%) are slightly less liable to injuries. The most frequent injuries in racket sports pertain to muscle tissues. According to this data, the majority of injuries occur halfway through a training session or a competition event, mostly during a competition season. The injuries primarily pertain to muscle tissues; these are followed by joint and tendon injuries. There are no differences between male and female players. Compared to other racket sports players, table tennis players suffer from fewer injuries.