Showing papers in "Medicina Sportiva in 2011"

Evidence-based resistance training recommendations

Abstract: Resistance training produces an array of health benefits, as well as the potential to promote muscular adaptations of strength, size, power and endurance. The American College of Sports Medicine (ACSM) regularly publish a position stand making recommendations for optimal achievement of the desired training goals. However, the most recent position stand (as well as previous ones) has come under heavy criticism for misrepresentation of research, lack of evidence and author bias. Therefore this paper proposes a set of scientifically rigorous resistance training guidelines, reviewing and summarising the relevant research for the purpose of proposing more logical, evidence-based training advice. We recommend that appreciably the same muscular strength and endurance adaptations can be attained by performing a single set of ~8-12 repetitions to momentary muscular failure, at a repetition duration that maintains muscular tension throughout the entire range of motion, for most major muscle groups once or twice each week. All resistance types (e.g. free-weights, resistance machines, bodyweight, etc.) show potential for increases in strength, with no significant difference between them, although resistance machines appear to pose a lower risk of injury. There is a lack of evidence to suggest that balance from free weights or use of unstable surfaces shows any transference to sporting improvement, and explosive movements are also not recommended as they present a high injury risk and no greater benefit than slow, controlled weight training. Finally, we consider genetic factors in relation to body type and growth potential.

Physical activity levels during a 6-week, school-based, active videogaming intervention using the gamercize power stepper in British children

Abstract: Introduction: Active video games have been purported to offer an alternative means by which children can be physically active but few data have examined this issue in ecologically valid settings. This study sought to assess physical activity levels during active videogame play and compare this to ‘free play’ associated with recess activity in a sample of British primary school children. Methods: Forty children (ages 10-11, 20 boys, 20 girls) from central England were randomly selected to participate in a 6 week, lunchbreak based, active video gaming intervention (n=20) or act as controls (n=20). Repeated measures analysis of covariance (controlling for body mass index) was used to examine any differences in physical activity, determined by pedometry and heart rate monitoring. Results: Children in the intervention accumulated significantly greater steps/min than controls during the first week of the intervention. The steps/min values were not significantly different at the mid point or during the last week of the assessment period. Irrespective of time point, children engaging in active video game play spent a lesser percentage of time engaged in MVPA than controls undertaking ‘traditional’ recess activity. Conclusion: Active video game physical activity using the Gamercize power stepper appears to be similar to physical activity levels during traditional school lunchbreak over a 6 week period. Active videogaming may therefore provide an alternative means to engage children in physical activity in the school setting.

Assessment of One Repetition Maximum (1RM) and 1RM Prediction Equations: Are they Really Necessary?

Abstract: Many well known resistance training authors and coaches believe that it is necessary to know an individual’s actual 1RM or predicted 1RM for each specific exercise. They claim that the accuracy of prescribing effective resistance training protocols is dependent on this information. This systematic review challenges that widely held belief and presents compelling evidence to the contrary. There is a direct relationship within individuals between muscular strength and performing a maximal number of repetitions with a submaximal resistance. This relationship does not change with training and is more relevant to progressive strength gains than knowing the actual or predicted 1RM, which appears irrelevant.

Is Body Fat a Predictor Variable for Race Performance in Recreational Female Ironman Triathletes

Abstract: Introduction and aim of the study: Low body fat is related to race performance in endurance athletes. We investigated whether characteristics of anthropometry, training or previous performance were related to race time in recreational female Ironman triathletes. Methods: In 31 female Ironman triathletes, with (mean and SD) 36.8 (6.2) years, 60.8 (6.2) kg body mass, 1.66 (0.06) m body height and a body mass index of 21.6 (1.3) kg/m2, anthropometric characteristics, such as body mass, body height, body mass index, circumferences and length of limbs, skin-fold thicknesses and body fat percentage, and characteristics of training, such as volume and intensity in all sub disciplines, were related to total race time including split times using correlations analysis. Also, personal best times in marathon running, Olympic and Ironman triathlons were related to race time. Results: Neither anthropometric nor training characteristics were related to total race time or split times. Personal best time in a marathon (r=0.51), personal best time in an Olympic distance triathlon (r=0.70) and personal best time in an Ironman triathlon (r=0.70) were significantly and positively related to total race time. Personal best time in an Olympic distance was significantly and positively related to personal best time in an Ironman triathlon (r=0.63). Conclusion: We must assume that previous performance is of higher importance than anthropometric or training characteristics for a successful race outcome in recreational female Ironman triathletes.

Effects of depth jump vs. box jump warm-ups on vertical jump in collegiate vs. club female volleyball players

Abstract: Introduction: Box jumps and depth jumps might elicit post activation potentiation, which can increase vertical jump performance. Aim: The purpose of this study was to compare the potentiating effects of a depth jump vs. a box jump warm-up on vertical jump performance. Methods: Eight collegiate and nine club female volleyball players participated on three testing days separated by 48 hours. Participants performed three pre-test countermovement vertical jumps with arm-swing then completed three experimental conditions in random order: control (no intervention), box jump (onto a box), and depth jump (stepping off a box with immediate maximal rebound). They then performed three post-test jumps. Results: Analysis revealed no significant (P < 0.05) interactions, but there was a main effect for time with all scores decreasing: vertical jump height (pre-34.31 ± 5.89cm; post-33.17 ± 5.86cm), relative ground reaction force (pre-24.18 ± 3.66N/kg; post-23.53 ± 3.66N/kg), and take-off velocity (pre-2.53 ± 0.29m/s; post-2.49 ± 0.30 m/s). Conclusions: It was concluded that using 10 depth or box jump warm-ups at the box height used in this study, with 10 minutes rest is not recommended to increase subsequent vertical jump performance in female collegiate volleyball players.

Body mass index of masters basketball players

Abstract: Aim and Scope: Thousands of masters athletes participate quadrennially in the W orld Masters Games (WMG). However, this unique cohort remains under investigated. With a need for multifaceted solution s to the global obesity epidemic, investigating special populations such as those competing in sport at mature-older a ges may further the understanding of the nexus between aging, physi cal activity and obesity. The aim of this cross-se ctional comparative study was to investigate body mass inde x (BMI) within the WMG competitors in context with national populations and health guidelines. We hypothesized that the prevalence of obesity in the WMG cohort would be less than comparative national populations and males would demonstrate a higher level of obesity than femal es. Methods: A total of 408 (44.1% male, 55.9% female) WMG basketball players aged 29-77yrs (mean 52.2, SD ± 8.0) wer e investigated via an online survey and compared to n ational populations, primarily a representative sam ple (n=12,366, 47.5% male, 52.5% female) of the Australian population (aged 30-79yrs). Results: Analysis demonstrated a significantly (p<0.001) reduced classification of o besity in masters basketball players, compared to A ustralian and other national populations. As expected, male basketball players had , on average, higher BMI than females (p<0.001). Conclusions: This study indicated that one key index of health, namely obesity, was on average far lower in WMG basketball players compared to a representative sam ple of population controls. This finding may indica te a lower risk for many diseases such as type 2 diabetes or heart diseases in masters basketball players and the sele ction of a sport that induces positive health related fitness for both ma le and female masters athletes.

Cardiorespiratory power and force-velocity characteristics in road cycling: the effect of aging and underlying physiological mechanisms

Abstract: Introduction: Although a considerable amount of research is available describing the physiological characteristics of competitive adolescent and senior level cyclists, research describing the same characteristics in master level cyclists is rare. Aim of this study was to compare cardiorespiratory power and force-velocity characteristics between two groups, one of master and one of senior level cyclists in an attempt to examine the effect of aging on these parameters. Methods: Eighteen master (43.25±5.37 y) and 13 senior level male road cyclists (28.78±4.95 y) were examined for anthropometric characteristics, body composition, and they performed the anaerobic force-velocity test and a graded exercise test to determine maximal oxygen consumption and anaerobic threshold. Results: Maximal heart rate (accordingly 176.9±13.8 bpm vs. 189.1±8.3 bpm) and heart rate at anaerobic threshold (157±13.9 bpm vs. 170.5±8.3 bpm) were the only parameters that differed significantly (P<0.001). Conclusions: Based on these results, it was concluded that optimal training could attenuate the decline of physiological parameters in cyclists until the beginning of the 5 th decade of human life. In addition, considering the variability of heart rate values (either maximal or at anaerobic threshold), i.e. wider range of scores in master than in senior level participants, it was suggested the need for individualized data, especially in master level road cyclists.

Physical Activity Patterns and Daily Steps in Brazilian Pregnant Women's Sample

Abstract: Purpose: to analyze the physical activity (PA) level of pregnant women (PW) according to their gestational trimester and to evaluate multiple measurements of PA. Methods: 122 PW, 26.5 ± 5.5 years old, and between the 4th and 37th week of pregnancy participated. PA was evaluated by levels of frequency and intensity, duration of walking, and moderate and vigorous PA; and based on the calculation in METs, determined by IPAQ and a pedometer. Data analysis was done by the Kruskall-Wallis, significance level of P<.05. Results: a significant decrease was found in the duration of moderate PA in the second-trimester group when compared to the duration of the first and the third trimester groups. There were no differences in walking (4.8 days/week) and moderate PA frequency (3.1 days/week) on average across trimesters. When considering the weekly number of steps, PW had in the first trimester taken an average of 10,789.0 ± 5,676.8 steps, in the second trimester 6,812.1 ± 4,092.4 steps, and in the third trimester 6,746.8 ± 3,572.0 steps. There was no significant difference in the weekly total number of steps between trimesters. Conclusion: the PA level of PW, using IPAQ or pedometer, was similar regardless of the trimester of the pregnancy.

Effects of High and Low Concentration Carbohydrate Solutions on Endurance Performance Consumed Prior to and During Intense, Intermittent Exercise

Abstract: The aim of the study was to compare the effects of high and low concentration carbohydrate (CHO) solutions on the endurance performance of recreational, male soccer players consumed prior to and during intense, intermittent exercise. Methods: Seven participants consumed four different fluids using a randomised double blind procedure, an 8% carbohydrate electrolyte solution (2.5% galactose and 5.5% glucose polymer) (8% CES), a 2.5% carbohydrate (2.5% galactose) electrolyte solution (2.5% CES), an electrolyte solution (E) and water (W). A further three participants acted as controls by consuming E only on four occasions. We used the Loughborough Intermittent Shuttle Test (LIST) to simulate the intense, intermittent nature of a soccer match. The LIST protocol consists of two parts: Part A required walking, jogging and sprinting, utilising a 20 m shuttle procedure, for 75 min, recovering for 3 min every 15 min. Part B required participants to perform intermittent running to exhaustion, alternating between 55% and 95% of their predicted maximal oxygen uptake. Each beverage was administered immediately prior to exercise (5 ml · kg-1) and every 15 min thereafter (2 ml · kg-1) until the conclusion of Part A. Results: The performance run times for Part B (mean ± SD) were 16.3 ± 1.5 min (8% CES), 11.1 ± 1.2 min (2.5% CES), 10.0 ± 1.0 min (E) and 9.3 ± 0.9 min (W). The 8% CES beverage produced a significantly greater time to exhaustion (Part B) than the other drinks (5.0 ± 1.5 min, P<0.05). Conclusions: A high CHO concentration formulation (8% CES) is associated with a significant increase in endurance performance during intense, intermittent exercise in recreational, male soccer players.

Effect of caffeine on fatigue during submaximal isometric contractions at different knee angles

Abstract: Introduction: In the knee extensors, the time to fatigue for intermittent isometric contractions can be increased by caffeine. Fatigue is muscle length dependent. Aim: We examined the effect of caffeine on fatigue of knee extensors at two joint angles. Methods: Ten male subjects (24±3 yr, 177±5 cm, 75±6 kg) with low caffeine intake (<200 mg·wk -1 ) volunteered. Study design was double-blind and counter-balanced. Subjects were administered caffeine (6 mg·kg -1 ) added to a non-caloric beverage or placebo, 1 hr before testing. Maximal voluntary isometric torque (MVIT) and intermittent contractions at 50%MVIT (15 s contraction, 5 s rest) were performed at knee angles of 30° and 90° (short and long length) until exhaustion. Fatigue was quantified by measurement of the MVIT 20 s post exhaustion. Surface EMG of m.vastus lateralis was analysed for root mean square (RMS). Data were analysed with 2-way ANOVA and paired t-tests with significance set at P<0.05. Results: MVIT values were similar for caffeine and placebo at both knee angles. Time to fatigue was higher at 30° for both conditions. Caffeine increased the time to fatigue, being equal by 15% (30°) and 13% (90°). The fatigue index was similar for both conditions and knee angles. Changes in RMS were similar for both conditions and knee angles [e.g. 30°: 154±14% (caffeine), 154±16% (placebo)]. Conclusions: Caffeine enhanced the time to fatigue during submaximal intermittent isometric contractions at different knee angles. However, potential mechanism(s) for the enhanced time to fatigue by caffeine do not seem to be muscle length dependent.

Changes in Morphological and Cytological Properties of Blood During Physical Exercise in Water at 4°C and 25°C

Abstract: Objective: The aim of this study was to determine the effect of a single swimming exercise till exhaustion, in water on the morphological and cytological blood parameters in laboratory rats. Methods: The experiment involved 60 male rats from the Wistar strain, aged 8 weeks and 36 weeks. The animals were separated into 6 groups: 3 groups (I, II, III) of 8-week old animals, and 3 groups (IV, V, VI) of 36-week old animals. The rats in the study groups i.e. II, III, V, and VI were made to swim till exhaustion in water at 4oC and at 25°C. After the experiment blood samples were collected from each rat and hematological and cytological determinations were completed for each sample. Results: Compared with the control group, in the rats from group II (8-week old, swimming in water at 4oC) a significant increase was noted in the RBC count, Hb, Ht, and MCHC, and MCH indices, whereas in the rats from group V (36-week old, swimming in water at 4oC) increases were noted in the MCHC and MCH indices (again when compared with the control group). In the rats from group III (8-week old, swimming in water at 25oC), compared with the control group, significant increases were noted in the Hb and Ht parameters, as well as in the MCHC, and MCH indices, whereas in the group VI rats (36-week old swimming at 25oC) – the increase was noted in the MCHC index. No alterations were found in the reticulocyte count, and in poikilocytes during exercise in water at low temperatures in either the 8-week or 36-week old rats. Conclusions: The increases in the majority of blood parameters, testifies to the dehydration of the body during physical exercise which in turn affects the microcirculation function. The lack of alterations in the reticulocyte count in the peripheral blood may, in turn, testify to the ineffectiveness of low temperature during exercise upon the function of the bone marrow.

The typical injures of motor organs in snowboard.

Abstract: The aim of the study was the attempt to determine the specifics of injuries suffered by people who do snowboarding recreationally. On account of the low number of cases one should determine the work as descriptive study. Methods. The research material was a group of 40 persons aged 18-30 practicing snowboarding. The research tool was a questionnaire prepared by the research authors. Results and Conclusions. The most frequent type of injury suffered by the questioned snowboarders was contusion (67,5%) and dislocation (50%) of joints. Injuries concerned the upper limb mainly (injures of the wrist/palm 50% of all) and the basic form of physical therapy applied in the examined group was criotherapy.