by Yoshinori Nagasawa and Shinichi Demura
Original Research
It is important to develop a method to accurately measure controlled force exertion (CFE) in order to evaluate coordination of neuromuscular function. This study aimed at examining the effect of short-term exercise on controlled force exertion in healthy young and middle-aged adults. Ten young (mean age = 20.7 y) and 10 middle-aged (mean age = 49.8 y) adults were included in the study. All subjects had a healthy central nervous system and had no disability in terms of motor functions. Also, none had engaged in regular exercise in the year prior to the study. Everyone participated in a general muscle strength training and aerobic exercise program twice a week during a 3-week period. They exerted the grip strength of the dominant hand and adjusted the grip strength based on the changing demand values displayed as a bar chart with a frequency of 0.3 Hz on a computer screen. A sum of errors between the demand values and the grip exertion values for 25 s was used as the evaluation parameter. A two-way analysis of variance (group and period) was used to examine significant differences among the means. Significant differences of variance were calculated to examine individual differences between the two groups by period. The middle-aged group had significantly greater errors than the young group. The errors decreased by approximately 20% in the young group and by approximately 10% in the middle-aged group during the second and third weeks. The variation in the errors in the middle-aged group was significantly greater than that in the young group during each period. In conclusion, we report that a combination of a general muscle strength training and aerobic exercise improves CFE in middle-aged and young adults. This effect is, however, less pronounced in middle-aged adults who also displayed a particularly small interindividual difference in CFE.
American Journal of Sports Science and Medicine. 2016, 4(3), 78-82. DOI: 10.12691/ajssm-4-3-3
Pub. Date: August 29, 2016
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by Rachael Irving
Original Research
Objectives: The aim of the study was to determine what factors account for the selection of athletes to represent Jamaica in track and field events at the Olympics and World Championships. Methods and materials: One hundred and twenty athletes who represented Jamaica between 1948-2015 in track and field events were interviewed. The athletes were classified based on athletic disciplines: Sprinter (S:100– 400m, n =80), jumper, hurdler and thrower (JHT, n = 23), and middle distance runners (Mdr: 800–3000m, n =17). The athletes were further sub-divided into athletes who represented Jamaica at the Olympic Games and the World Championships (highest level games) and those who represented Jamaica at the Pan-American, Commonwealth, World Junior Championships, World Youth Olympics, World University Games and the CARIFTA Games (other games). Each athlete was administered a questionnaire. The questionnaire was designed based on models used in studies elite athletes from Ethiopia Kenya and Jamaica who were competitors in international games. The questions elicited the following information: age, gender, event/s participated in, place of birth of athlete and parents, secondary/high school athlete attended and yes or no for living arrangements with adult/s) other than family members during athletic development in high schoool. The data were analyzed using the Statistical Packages for the Social Sciences, Version 21. Statistical significance was set at P <0.05%. Cross tabulations for statistical associations and binary regression for influence of independent variables on a dependent variable were utilized in the analysis. Results: The majority of athletes, 83.3% who represented Jamaica in track and field and their parents, 79.2% were born in Jamaica. There were slightly more females than males, 50.8 % versus 48.2%. Approximately 91.7% of athletes attended high school in Jamaica defined as having a strong history of participation in athletics and 85% lived with adults other than family members during athletic development at the high school level. More than 66% of athletes participated in the 100-400m sprints but only 26.6 % of participants were selected to represent Jamaica in the highest level games. Secondary/high school the athlete attended influenced selection to represent Jamaica in the highest level games and in the sprint events. Conclusion: Selection to represent Jamaica in the sprint events at the Olympics and World Championships is influenced by the secondary school the athlete attended.
American Journal of Sports Science and Medicine. 2016, 4(3), 74-77. DOI: 10.12691/ajssm-4-3-2
Pub. Date: June 20, 2016
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by Bradley J, Kerr S, Bowmaker D and Gomez J-F
Original Research
Swimming is a popular sport, both recreationally and competitively. The repetitive nature of the swim stroke places unique demands on the body. Competitive swimmers spend a considerable amount of time training for their sport, and can swim 110km or more a week. As a consequence of this amount of swimming and the repetitive nature of the swimming stroke, swimmers can develop injuries, most commonly localised to the shoulder. This manuscript will focus on shoulder problems in swimmers and present a review of the factors that may predispose an individual to injury. The EBCSOhost Research Database was initially searched using the keywords: “(Swimming OR Swimmers”) AND “(Competitive OR Shoulder)” AND “(Injury OR Pain)”. This was supplemented by cross-referencing to publications cited by the authors of the initial literature search. Effect sizes (Cohen’s d) were calculated to compare the different factors associated with shoulder injury. A review of literature split factors associated with shoulder problems into six groups: biomechanics of the shoulder; general swimmer characteristics; injury history; shoulder laxity and range of movement; shoulder strength; general strength. The impact of each factor upon swimming and shoulder injury is discussed and the effect sizes show which factors have the greatest association with shoulder injury in swimmers.
American Journal of Sports Science and Medicine. 2016, 4(3), 57-73. DOI: 10.12691/ajssm-4-3-1
Pub. Date: June 16, 2016
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