International SportMed Journal - Volume 14, Issue 4, 2013
Volume 14, Issue 4, 2013
A comparison of training with light, regular and heavy balls with the same workload on overhead throwing velocity with different weighted balls in children : original research articleSource: International SportMed Journal 14, pp 85 –195 (2013)More Less
Background: Throwing is a fundamental ability that children learn during their youth. There are different ways to train this throwing ability in children.
Research question: The aim of this study was to examine the effect of training throwing in children with light, regular or heavier balls in an overhead throwing movement and transferring to other ball weights after a short training period. It was hypothesised that all training groups would significantly improve their throwing velocity due to the throwing training, but that each group increased the most with the ball they trained with during the training period because of the specificity principle.
Type of study: A randomised controlled study.
Methods: Thirty primary school children (age 8.5 ± 0.5 yr, body mass 33.3 ± 6.7kg, height 1.35 ± 0.04 m), divided into three groups (underweight ball: 0.35 kg, regular ball: 0.45 kg and overweight ball: 0.5 kg training group), participated in the study. Each group conducted the same total throwing workload twice a week for six consecutive weeks. Throwing velocity and distance with a 0.35 kg, 0.45 kg, 0.5 kg and a 1 kg ball was tested before and after a training period.
Results: A significant (p ≤ 0.05) increase in throwing velocity (10-18%) and distance (16-19%) was found after the six-week training period with every ball with no significant differences between groups.
Conclusions: This study indicates that training workload is of importance for enhancement of ball throwing performance and not especially for the ball weight that is thrown with for children. Furthermore, this training also had a positive effect upon throwing performance with heavier balls (1 kg) indicating that transfer to heavier balls is possible in throwing for children.
Comparison between a laboratory test in kayak-ergometer and continuous and interval exercises on open water in well-trained young kayakers : original research articleSource: International SportMed Journal 14, pp 196 –204 (2013)More Less
Background: It has been suggested that heart rate and blood lactate determined in a constant intensity test in the kayak-ergometer may be valid for programming training intensities during constant exercise.
Research question: The purpose of this paper is to determine the physiological and physical differences obtained during kayak ergometer paddling and on-water kayak paddling using well-trained junior paddlers.
Type of study: Descriptive study.
Methods: Twelve male kayakers (16.5 ± 1.9 yrs.) performed an incremental laboratory test in which blood lactate concentrations, heart rate (HR), rate of perceived exertion (RPE) and stroke rate (SR) were recorded and velocities at 2.5 and 5 mmol∙L-1 were calculated. Two days later, the participants carried out a Continuous training exercise (CT) on open water (8000 m) at a velocity equivalent to a lactate concentration of 2.5 mmol∙L-1, and the next day they followed an Interval training exercise (IT) (8 x 1000 m) at a velocity equivalent to a lactate concentration of 5 mmol∙L-1. A linear regression analysis was performed to check the predictive validity of the variables obtained on the kayak ergometer for the training exercises and the differences between the variables were analysed using the paired t-test.
Results: Significant differences in HR and RPE (p<0.001) were observed between the IT and the kayak ergometer. There were also significant differences in SR (p<0.01) between Continuous and Interval training exercises and the kayak ergometer. The results showed that well-trained kayakers recorded lower values of blood lactate concentration and SR in the CT and IT exercises than on the kayak ergometer. Additionally, Lactate concentration was significantly lower (p<0.01) than expected in CT and IT. The SR obtained in 8000 m CT was significantly lower (p<0.01) than the SR estimated in the laboratory test at a blood lactate concentration of 2.5 mmol∙L-1.
Conclusion: This suggests that coaches should pay attention to this fact when using laboratory test results for programming and monitoring training on open water.
Seasonal variations in body composition and fitness parameters according to individual percentage of training completion in professional soccer players : original research articleSource: International SportMed Journal 14, pp 205 –215 (2013)More Less
Background: The purpose of this study was to examine changes in anthropometric and physical fitness parameters in male professional soccer players during the competitive soccer season.
Methods: 42 soccer players (mean ± SD; age= 25 ± 5.2 years, mean height= 177.3 ± 6.74 cm, mean body mass= 75.8 ± 5.97 kg) were tested. Variation in body composition and performance in squat jump (SJ), countermovement jump (CMJ), Abalakov jump (ABK), and VAMEVAL maximal incremental running test were evaluated in 3 time points (E1 before the season, E2 at the end of pre-season period, and E3 during the middle of the season) throughout 2 consecutive seasons. Individual percentage of training completion was quantified.
Results: From E1 to E2, VO2max and maximal aerobic velocity significantly increased (61.99 ± 2.78 vs. 63.87 ± 2.80 ml∙kg-1∙min-1 and 19.19 ± 0.77 vs. 19.70 ± 0.70 km∙h-1, respectively) and the percent body fat and percentage of skeletal muscle were significantly different (10.99 ± 1.02 vs. 10.34 ± 0.73 and 47.96 ± 0.96 vs. 48.63 ± 0.83, respectively). No differences were observed in SJ, CMJ, and ABK between 3 evaluation moments. Influence of individual percentage of training completion was correlated to changes in muscle weight (E1 to E2; r=0.54, and E2 to E3; r= 0.39).
Conclusions: This study suggests that male professional soccer players with high individual percentage of training completion have higher capabilities to increase or maintain muscle mass throughout the season.
Is the underwater gliding test a valid procedure to estimate the swimmers' drag? : original research articleSource: International SportMed Journal 14, pp 216 –225 (2013)More Less
Objective: The aim of this study was to develop a structural equation model for underwater gliding distance based on its determinant variables, in order to confirm whether it is an informative test of young swimmers' hydrodynamic profile.
Methods: Twenty-three subjects (twelve boys and eleven girls with a mean age of 13.61 ± 0.83 years old) were evaluated. The following were determined: (i) the underwater gliding distance; (ii) the squat jump performance; (iii) the passive drag; (iv) the passive drag coefficient; (v) the trunk transverse surface area and; (vi) the gliding velocity.
Results: The underwater gliding distance was significantly correlated with the squat jump (rs = 0.47; p = 0.038) and with the coefficient of passive drag (rs = -0.55; p < 0.01) but not with passive drag (rs = 0.41; p = 0.09). The overall model explained 45% of the underwater gliding distance (x2/df = 3.138).
Conclusion: The underwater gliding distance seems to be more dependent from the squat jump than from the passive drag. Therefore it seems as if the underwater gliding test is not representative of the swimmers' passive drag or his /her passive drag coefficient.
Physiological and performance responses of elite North African and European endurance runners to a traditional maximal incremental exercise : original research articleSource: International SportMed Journal 14, pp 226 –235 (2013)More Less
Background: A variety of studies have been undertaken on East and South African athletes to identify the factors that underlie the superior performance of African runners. However, the physiological response of North African runners to exercise remains unknown.
Research question: Investigate the physiological response to exercise in North African and European runners.
Type of study: Descriptive study.
Methods: Eight North African and 13 European runners completed a maximal incremental running test, starting at 9 km∙h-1 and speed increased by 1.5 km∙h-1 every 4 minutes, with 1 minute of recovery between workloads. Respiratory parameters were measured and blood lactate concentration and rating of perceived exertion (RPE) were assessed.
Results: North African and European runners achieved similar maximal aerobic velocity (MAV) (20.5 ± 1.7 vs. 19.9 ± 1.3 km∙h-1, respectively) and peak treadmill velocity (PTV) (20.8 ± 0.7 vs. 20.7 ± 1.1 km∙h-1). However, MAV was slower than PTV in the European runners (p < 0.05), but not in North Africans. North African runners presented a lower respiratory exchange ratio at 16.5 km∙h-1 (1.03 ± 0.03 vs. 1.07 ± 0.05) and 18 km∙h-1 (1.07 ± 0.03 vs. 1.12 ± 0.06) and a lower RPE at 18 km∙h-1 (3.9 ± 0.8 vs. 5.1 ± 1.2) than the European runners (p < 0.05).
Conclusions: This study provides evidence that North African runners were able to maintain a higher MAV relative to PTV and lower RPE than the European runners. However, the absence of differences in variables such as VO2max or running economy suggest that the success of North African runners cannot be explained by differences in metabolic efficiency.
Source: International SportMed Journal 14, pp 236 –244 (2013)More Less
Background: Exercise testing is a diagnostic tool for evaluating the induction of stress-induced paroxysmal atrial fibrillation (PAF). Resting P-wave dispersion has been suggested to be greater in males versus females but if used by clinicians, gender difference in response to exercise must be determined.
Methods: Sixteen healthy subjects (n=8 male, age: 21±0.3; n=8 female, age: 23±1.4) performed an incremental exercise test using the Bruce protocol. Electrocardiograms were recorded at rest, end-exercise, 1, 3, and 5 mins recovery. P-waves were measured in each lead with the maximum (P-max) and minimum (P-min) P-wave durations and dispersion calculated.
Results: There was a significant decrease in P-max from rest to end-exercise in males and females [males, 118.3±7.4 (95%CI: 109.7 to 126.8ms) vs. 97.9±6.2 (89.3 to 106.4ms); females, 109.4±4.5 (100.8 to 117.9ms) vs. 94.3±4.6 (85.7 to 102.8ms); p=0.001 (5.7 to 29.8ms)]. Similarly, for P-min [males, 65.6±5.6 (57.4 to 73.9ms) vs. 50.8±2.7 (42.5 to 59.0ms); females, 58.4±3.3 (50.1 to 66.6ms) vs. 45.6±2.7 (37.4 to 53.9ms); p=0.01 (2.2 to 25.4ms)]. Irrespective of gender there was limited change in P-wave dispersion in response to exercise. Males had a longer P-max versus females during the protocol [109.6±2.3 (105.8 to 113.4ms) vs. 103.6±1.8 (99.8 to 107.4ms); p=0.03] but this was not stage-specific. There was no gender differences in either P-min (p=0.12) or P-wave dispersion (p=0.64) across the protocol or stage-specific.
Conclusions: Results from this study indicate that in contrast to P-max and P-min, the P-wave dispersion may not be significantly influenced by the sympathetic nervous system in males and females. Therefore, this study suggests males and females should be evaluated in the same way using the P-wave dispersion for predicting the development of stress-induced PAF at rest and during exercise testing protocols.
Traumatic and overuse injuries among elite adolescent alpine skiers : a two-year retrospective analysis : original research articleSource: International SportMed Journal 14, pp 245 –255 (2013)More Less
Background: Injury registrations of competitive young athletes are crucial for injury prevention. Particularly in alpine skiing, limited published data exist.
Research question: Aimed to profile the rate of injuries affecting skiers admitted to a ski boarding school. Of particular interest was the comparison of overuse and traumatic injuries during the winter and summer seasons.
Type of study: 2-year retrospective survey.
Methods: Multiple interviews were conducted with 104 elite alpine skiers, ages 15-18 years, from a ski boarding school in Austria. The injury risk and characteristics of ski specific injuries were evaluated.
Results: Overall, 89 skiers reported a total of 235 injuries (88 among females, 147 among males). Of the 61 male skiers, 40 sustained at least one traumatic injury (injury risk = 0.67) and 34 reported an overuse injury (injury risk = 0.56). Of the 43 females, 29 suffered at least one traumatic injury (injury risk = 0.67), and 26 reported an overuse injury (injury risk= 0.60). The risk of sustaining a traumatic injury was higher during the winter season (RR 1.39, 95% CI 1.02-3.42, P<0.05), and these injuries mainly affected the lower extremities. During the summer season, there was a higher risk for overuse injuries (RR 1.46, 95% CI 0.96-2.20, P<0.05), and most of these injuries were localised to the trunk and back.
Conclusion: The occurrence of traumatic injuries during the competitive season is high. Overuse injuries accounted for a relatively high proportion of time-loss injuries during summer training, suggesting that we should focus not only on traumatic injuries but also on overuse problems.
Pregnancy and sport : recommendations for physical activity during pregnancy and puerperium (after childbirth) : FIMS Position Statement 2013Author Ulrike Korsten-ReckSource: International SportMed Journal 14, pp 256 –259 (2013)More Less
Pregnancy leads to considerable physiological changes in hemodynamics, the musculoskeletal system, metabolism, the endocrine system and the psyche. Therefore physical activity during pregnancy could have benefits concerning these changes and has already been attested to in many studies. But it has to be taken into account that an uncomplicated pregnancy is a requirement for regular physical activity. If appropriate, former physical activities can be maintained, but performance-oriented exercise and competitions, however, are not recommended. Women can and should adjust their physical activity according to their individual situation with the focus of attention on their subjective body perception. The higher energy turnover which is achieved through physical activity has a positive impact on the health of mother and child. In general, at four weeks after delivery, systematic training could be restarted. The following recommendations include general information on endurance and weight training during pregnancy.
Exercise as an intervention for osteoarthritis of the knee : a review of the literature : review articleSource: International SportMed Journal 14, pp 260 –293 (2013)More Less
Objective: The objective of this review was to examine the evidence and provide recommendations for utilising therapeutic exercise in the treatment of osteoarthritis (OA) of the knee.
Data sources: The PubMed Database was searched 07 July, 2011 for articles in English using the terms "osteoarthr*" AND "knee" AND each of the following, individually: Exercise; Strength; Resistance; Aerobic; Isometric; Isotonic; Isokinetic; Concentric; Eccentric; Aquatic; Dynamic; Balance; Agility; Tai Chi; and Yoga. The search excluded articles related to rehabilitation following arthroplasty. Clinical trials were the primary focus of the search.
Study selection: The initial search identified 181 articles.
Data extraction: Articles were eliminated if they were either redundant, not relevant, not in English, cost analyses, used an intervention other than exercise, or were not clinical trials. Reference lists were hand searched for additional articles not identified in the PubMed search and two studies known to the authors but not identified in the search were included.
Data synthesis: A total of 91 trials were identified for inclusion in the narrative review.
Conclusion: The literature strongly indicates various types of therapeutic exercise such as resistance training, walking, cycling, aquatic, Tai Chi, and balance and agility training are effective for reducing symptoms and improving function among persons with knee OA. Rehabilitation clinicians should consider factors such as patient preference, equipment availability, costs and presenting symptoms when designing exercise based rehabilitation programmes for patients with knee OA.
A review of enablers and barriers to physical activity participation among older people of New Zealand and international populations : review articleSource: International SportMed Journal 14, pp 294 –312 (2013)More Less
Objective: The objective of the present study was to review international evidence on common motivators and barriers to physical activity for older people.
Data sources: Authors searched Pubmed, PsychINFO, EBSCOhost, Scopus, CINAHL, PsycARTICLES, Google Scholar, Ausportmed, and SPORTDiscus, plus additional hand searches. Relevant terms included: 1) physical activity, sport, exercise, sedentary, inactivity; 2) older people, older adults, aged, elderly; and 3) barriers, facilitators, enablers, motivators. The search was limited to English language publications from 2003 to 2010.
Study section: Article titles (n = 504) were reviewed for potential relevance by two authors, then full-text articles were retrieved for all potentially relevant articles. Twenty-seven English language articles, reports, or abstracts published from 2003 to 2010, addressing motivators or barriers to physical activity in people over the age of 65 years were included.
Data extraction: Two authors extracted data on motivators and barriers.
Data Synthesis: Based on frequency, the most common barriers and motivators to physical activity (PA) participation, categorised at the personal, social, and environmental levels were identified. Common PA motivators included positive outcome expectations, feeling healthy, social support, easy access to facilities or affordable community-based programmes, guidance or encouragement from health professionals, and institutional encouragement. Common PA barriers included health problems, lack of support, cultural/social norms, functional ability, and the fear of falling and injury.
Conclusions: For both New Zealand and international populations, common personal, social, and environmental barriers and motivators were identified that could be targeted through public health programmes, which should be culturally appropriate for each ethnic group.