International SportMed Journal - Volume 15, Issue 2, 2014
Volume 15, Issue 2, 2014
Source: International SportMed Journal 15, pp 113 –122 (2014)More Less
Bone is a remarkable, very strong and flexible structure. Running and jumping, together with muscle work, and lever arms generate ground reaction forces helping to model developing bone. Peak bone mass, strongly determined by genetic factors and exercise, is one of the most important factors in bone health. The amount of bone accrued, especially before the end of the third decade of life, is a major determinant of the risk of fractures in later life.
Bones are a living tissue and constantly changing throughout one's lifetime, thus manifold osteopathies are known. The bone itself does not need to be the primary cause of diseases, but rather be affected in combination with other diseases. Besides osteopathies, such as fractures, achondroplasy, Morbus Paget, etc., osteoporosis which is defined as a systematic skeletal disease characterised by low bone mass and micro-architectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture, according to the World Health Organization (WHO), is ranked among the ten prime widespread diseases. Bone mineral density (BMD) is used in diagnosing osteoporosis. Anamnesis and clinical findings, bone densitometry, medical imaging and the basic laboratory are basic diagnostics for osteoporosis. Physical inactivity, medication, sex, age, low body mass index, need to be regarded as risk factors for osteoporosis. Acute and chronic pain caused by osteoporosis restricts activities of daily living and diminishes quality of life. FRAX (a diagnostic tool), disregarding all advantages and disadvantages of the computer based algorithm, calculates the country-specific 10-year-probability of a major hip fracture.
Several different bone disorders, especially osteoporosis, are among other reasons linked to a sedentary lifestyle and poor nutrition habits. Preventing osteoporosis is a lifelong task, involving aspects such as nutrition and body weight, physical activity, as well as the abuse of dependence-causing substances. Thus lifestyle modification, calcium, vitamin D3, physical activity, exercise and prevention of falls establish the basic therapy for osteoporosis. Building on this, secondary and tertiary prevention addresses the risk of fracture and repeated fracture prevention via medication. Physical medicine represents not merely an alternative, but rather a complementary and inevitable therapy option in treating bone disorders, especially osteoporosis. Consequently, physical exercise plays a key role in reducing fractures and repeated fractures. The study situation concerning physical activity and osteoporosis is so far not easy to evaluate, because interventions disagree on duration, intensity, specificity, and subject groups. Although there is a vast amount of literature on physical activity (described as one of the best medications against diseases of lifestyle), there is a lack of consensus according to the best dose-response correlation for bone health. In the context of bone health, particular attention is paid to whole body vibration. Whole body vibration may improve muscle strength and power and consequently bones and balance as well. However, the mechanism is not well understood and the exact role is still debated and cannot be uniformly prescribed.
As society grows older and lifestyle becomes more and more sedentary, the occurrence of osteoporosis should be held as low as possible and therefore the diagnostic methods need to take action to recognise indications of osteoporosis as soon as possible and be able to determine the most effective treatment options.
Changes in strength and aerobic performance by concurrent training in under-19 soccer players : original research articleSource: International SportMed Journal 15, pp 123 –135 (2014)More Less
Background : This study aimed to determine: 1) the changes in the physical conditioning of under-19 soccer players, 2) the effects of strength training using resistance executed as a function of the speed of a Smith machine bar, 3) relationships between heart rate (HR) values recorded during training and competition and changes in players' physical conditioning.
Methods : Nineteen field players from a team in the U-19 Spanish first division participated in the study. Changes in jump ability (CMJ, CMJL), bar movement speed in a loaded full squat (FSL), sprint time over 30m (T10, T20, T30, T10-20, T10-30, T20-30), and maximal aerobic speed (MAS) were evaluated three times (E1, E2, E3) during the fourth months studied. Players' HR during practices and matches were recorded. Improvements in MAS, application of strength in CMJ, CMJL, and FSL were reported, while the players significantly worsening their sprint times.
Results : No significant relationships were found between HR values and changes in players' physical conditioning. Changes in sprint times (T30 and T10-30) were correlated with changes in bar speed for the FS60kg (r = 0.53-0.64, p < 0.05) and volume of strength training performed (r = 0.53-0.59, p < 0.05). These improvements in strength did not induce expected improvement in sprint time, possibly due to the interference effect between concurrent aerobic and strength training.
Conclusions : The results suggests that improved ability to accelerate could be related to improvements in loaded full squats moving at speed near 1m.s-1, and the inhibitor effect obtained shows the importance of monitoring the intensity of aerobic training.
Discrepancy between knowledge and interest of Austrian sports physicians with respect to doping and doping prevention in sports : original research articleSource: International SportMed Journal 15, pp 136 –145 (2014)More Less
Background : Because athletes rely on sports physicians as a source of information, physicians must be included in research relating to doping prevention. According to several studies, the level of knowledge of sports physicians with regard to doping prevention seems to be inadequate. It is crucial for them to have a comprehensive understanding of doping regulations, substances and the side effects, as well as the procedure for issuing Therapeutic Use Exemptions (TUE).
Research questions : (1) to evaluate the knowledge of Austrian sports physicians regarding doping substances, doping methods and side effects and (2) to provide ideas on efficient strategies to educate this target group.
Methods : An online questionnaire was distributed to all registered Austrian physicians who hold a Supplementary Diploma in Sports Medicine (n = 1,543). The questionnaire was administered over four months and structured into eight areas of interest. Chi-Square tests, as well as descriptive statistics, were used to analyse the data.
Results : A total of 152 physicians returned the questionnaire (response rate of 9.8%). Some 53.7% subjectively believed that they were poorly informed about the topic, and 43% reported that they knew of the World Anti-Doping Agency (WADA) 2011 Prohibited List. Knowledge deficits regarding substances (especially insulin, recombinant human erythropoietin, stimulants) and strong uncertainties with regard to prohibited doping methods and the side effects of specific substances were reported. This low level of knowledge stood in contrast to the high interest in the topic that the physicians self-reported. In general, physicians had a very positive anti-doping attitude.
Conclusion : Results of this study are comparable with previous studies conducted in Germany and France. Despite the low response rate, this study demonstrated high interest from sports physicians regarding doping, and showed some of the deficits in their knowledge of doping. Integrating anti-doping related information within educational material may assist increasing the knowledge of sports physicians and gain their support for wider anti-doping strategies.
The reliability of force-time variables recorded during vertical jump performance and their relationship with jump height in power trained athletes : original research articleSource: International SportMed Journal 15, pp 146 –155 (2014)More Less
Background : Vertical jump tests have been put forward as a measure of explosive strength, yet the importance of rate of force development (RFD) to vertical jump performance remains unclear.
Research question : To determine the reliability of force-time variables recorded during countermovement jumps (CMJ) and to investigate the relationships between force-time variables and jump height (JH).
Type of study : A cross-sectional experimental design.
Methods : Thirty-five male resistance-trained subjects (mean ± SD: age 24.7±1.3 years; mass 71.3 ± 56.4 kg; height 1.76 ± 0.06 m) involved in distinct power sports participated in the present study. Each subject performed three maximal CMJ trials in a Smith Machine with three minutes of rest between jumps. A linear position transducer was fixed to the barbell which provided instantaneous vertical position data from which the mechanical variables of high jump, peak vertical force (PF), time to peak vertical force (PFtime), maximum rate of force development (RFDmax), time to maximum rate of force development (RFDtime) and percentage of PF at RFDmax (RFD%PF). The reliability of the force-time variables was assessed by calculating the change in the mean, the coefficient of variation (CV), and the intraclass correlation coefficients (ICC). The relationship between the force-time variables and JH were assessed using correlation coefficients.
Results : All force-time variables demonstrated acceptable reliability (CV range: 3.3-12.4%; ICC range: 0.80-0.92). RFDmax, PFtime and RFDtime demonstrated very large correlations with jump height (r > 0.80), while both PF and RFD%PF demonstrated high correlations with CMJ performance (r > 0.50).
Conclusions : The force-time variables calculated during CMJ using a linear position transducer are reliable. Furthermore, the rapid development of force is an important determinant of JH during CMJ performed with a low external load in well-trained athletes, and so JH represents a valid measure of explosive strength.
The relationship between golf performance, anthropometrics, muscular strength and power characteristics in young elite players : original research articleSource: International SportMed Journal 15, pp 156 –164 (2014)More Less
Background : The aim of this study was to determine the relationship between golf performance (handicap, drive ball speed, approach and putting accuracy), anthropometrics and muscular strength and power in young elite golfers.
Type of study : Observational, descriptive and transversal study, with accidental sampling (non-randomised).
Methods : Forty-four male golfers participated in the study and the following information was obtained: anthropometrics, drive ball speed, approach accuracy, putting accuracy, medicine ball throwing speed, countermovement jump, bench press and parallel full squat. The relationship between these variables was assessed using Pearson's correlation coefficient, while a regression analysis was performed to assess which parameters were the best predictors of handicap.
Results : The main results showed that peak and average drive ball speeds were the only golf performance indicators significantly correlated to handicap (r = -0.58 to -0.61, P<0.001). Significant correlations were observed between drive ball speed and body mass (r = 0.4, P<0.01). In addition, handicap and drive ball speed correlated significantly with muscular strength and power, even when adjusted with the anthropometric characteristics (r = 0.50 to 0.70; P<0.01). Finally, the regression analysis showed that 68.7% of the total variance in handicap was explained by height, drive ball speed average and medicine ball throwing performance.
Conclusions : The high correlations found between drive ball speed, handicap and upper- and lower-body strength suggest that muscular strength and power are important. These results have important applications as it could help coaches with optimal development of physical and sport-specific conditioning and golf training programmes.
"Young" masters vs. elite swimmers : comparison of performance, energetics, kinematics and efficiency : original research articleSource: International SportMed Journal 15, pp 165 –177 (2014)More Less
Background : Competition in masters swimming is getting tougher. Athletes are dedicating more time and effort to excel in masters competitions than they use to.
Research question : What are the factors associated with masters and elite swimmers performance?
Type of study : A cohort group comparison (young master versus elite swimmers) and a correlational study (association between selected variables and performance) were conducted.
Purpose : The aim was to identify the energetics, kinematics and efficiency variables associated with young masters (former elite) and elite swimmers performance as well as compare it between both cohort groups.
Methods : Twenty male swimmers (masters: N=8, 29.75±3.80-y; elite: N=12, 20.41±3.20-yld) performed a 7x200m freestyle swim. The performance (200m freestyle at official competition), velocity at which the 4 mmol.l-1 of blood lactate was assessed (V4), peak blood lactate concentrations (Lapeak), peak oxygen up-take (VO2peak), minimum velocity to elicited VO2peak (vVO2peak), total energy expenditure (Ètot), stroke frequency (SF), stroke length (SL), mean swimming velocity (v), energy cost (C), stroke index (SI) and propelling efficiency (ηp) to check whether this was achieved.
Results : Elite swimmers presented a better performance. V4, VO2peak, vVO2peak, Ètot, SF, v and SI were significantly higher in elite swimmers. For both groups performance was associated with the V4, vVO2peak and v. In addition, elite swimmers' performance was impaired with regard to the Lapeak.
Conclusions : Young masters swimmers presented impairment in performance related to a decrease in the energetics profile and biomechanical behaviour. Nevertheless, their previous background as elite swimmers allowed them to maintain high swimming efficiency.
Blood pressure and heart rate variability responses after isolated and combined sessions of aerobic and strength exercises : original research articleSource: International SportMed Journal 15, pp 178 –187 (2014)More Less
Background : Few studies have investigated the effect of exercise order on post-exercise hypotension and heart rate variability (HRV).
Research question : The purpose of this study was to investigate the behaviour of blood pressure (BP), heart rate (HR) and HRV after an aerobic training session (ATS), strength training session (STS), combined aerobic and strength training session (ASTS) and in the opposite order (SATS).
Type of study : Acute effect study.
Methods : Ten men (age 24.5 ± 1.1 years, weight 77.0 ± 3.7 kg, height 1.76 ± 0.8 cm) with previous experience in aerobic and strength training volunteered for this study. STS was performed using eight exercises (with 60% 1RM) and each ATS was performed on a cycle ergometer (60% VO2 peak, 50 min). BP, HR and HRV were measured at rest and for one hour following exercise.
Results : The results demonstrated reductions in systolic BP after ASTS and SATS when compared to the control group (CON) (p <0.05), ATS (p <0.01) and STS (p <0.05). On the other hand, HR was elevated after STS (p <0.01), ASTS (p <0.01) and SATS (p <0.05) when compared to the CON group. The HR increase was accompanied by changes in HRV after sessions of STS (p <0.01), ASTS (p <0.01) and SATS (p <0.01) compared to the CON group.
Conclusions : Combined sessions of aerobic and strength training with moderate intensity can elicit a hypotensive response in normotensive men independent of session order. Therefore strength and conditioning professionals can prescribe these exercises using different orders if the objective of the training session is to control blood pressure.
Effects of saddle height on knee forces of recreational cyclists with and without knee pain : original research articleSource: International SportMed Journal 15, pp 188 –199 (2014)More Less
Background : Low saddle height has been empirically linked to increased compressive force at the patellofemoral joint and to the development of overuse knee pain.
Research question : How changes in saddle height would affect patellofemoral and tibiofemoral forces of cyclists with and without knee pain.
Type of study : Cross-sectional.
Methods : Sixteen cyclists without knee pain and eight cyclists with knee pain performed four 2-minute submaximal cycling trials using their preferred saddle height, two saddle heights (high and low) eliciting ±10° change in knee flexion angle, in relation to their preferred saddle height, and a saddle height eliciting 25° knee flexion at the 6 o'clock crank position. Workload (3.04 ± 0.78 W/kg) was consistent and pedalling cadence was visually controlled at 90 rpm for every trial. Right pedal forces and joint kinematics recorded during all trials enabled calculation of patellofemoral and tibiofemoral forces using a musculoskeletal model.
Results : Changes in saddle height did not substantially affect patellofemoral and tibiofemoral forces when comparing cyclists with and without knee pain. Compared to the low saddle height there were larger anterior tibiofemoral forces at optimal (35% without pain, 51% pain) and high saddle heights (76% without pain, 92% pain).
Conclusions : Bicycle saddle height can probably be set within a large range of knee motion (i.e., ~44-65° determined during dynamic cycling at the 3 o;clock position) to minimise possible detrimental effects of large patellofemoral and tibiofemoral forces.