Time filter

Source Type

Mujika I.,University of the Basque Country | Mujika I.,Finis Terrae University | Stellingwerff T.,Canadian Sport Institute Pacific | Tipton K.,University of Stirling
International Journal of Sport Nutrition and Exercise Metabolism | Year: 2014

The adaptive response to training is determined by the combination of the intensity, volume, and frequency of the training. Various periodized approaches to training are used by aquatic sports athletes to achieve performance peaks. Nutritional support to optimize training adaptations should take periodization into consideration; that is, nutrition should also be periodized to optimally support training and facilitate adaptations. Moreover, other aspects of training (e.g., overload training, tapering and detraining) should be considered when making nutrition recommendations for aquatic athletes. There is evidence, albeit not in aquatic sports, that restricting carbohydrate availability may enhance some training adaptations. More research needs to be performed, particularly in aquatic sports, to determine the optimal strategy for periodizing carbohydrate intake to optimize adaptations. Protein nutrition is an important consideration for optimal training adaptations. Factors other than the total amount of daily protein intake should be considered. For instance, the type of protein, timing and pattern of protein intake and the amount of protein ingested at any one time influence the metabolic response to protein ingestion. Body mass and composition are important for aquatic sport athletes in relation to power-to-mass and for aesthetic reasons. Protein may be particularly important for athletes desiring to maintain muscle while losing body mass. Nutritional supplements, such as b-alanine and sodium bicarbonate, may have particular usefulness for aquatic athletes' training adaptation. © 2014 Human Kinetics, Inc.

Gathercole R.,University of Victoria | Sporer B.,University of Victoria | Stellingwerff T.,Canadian Sport Institute Pacific | Sleivert G.,Canadian Sport Institute Pacific
International Journal of Sports Physiology and Performance | Year: 2015

Purpose: To examine the reliability and magnitude of change after fatiguing exercise in the countermovement-jump (CMJ) test and determine its suitability for the assessment of fatigue-induced changes in neuromuscular (NM) function. A secondary aim was to examine the usefulness of a set of alternative CMJ variables (CMJ-ALT) related to CMJ mechanics. Methods: Eleven male college-level team-sport athletes performed 6 CMJ trials on 6 occasions. A total of 22 variables, 16 typical (CMJ-TYP) and 6 CMJ-ALT, were examined. CMJ reproducibility (coefficient of variation; CV) was examined on participants' first 3 visits. The next 3 visits (at 0, 24, and 72 h postexercise) followed a fatiguing high-intensity intermittent-exercise running protocol. Meaningful differences in CMJ performance were examined through effect sizes (ES) and comparisons to interday CV. Results: Most CMJ variables exhibited intraday (n = 20) and interday (n = 21) CVs of <10%. ESs ranging from trivial to moderate were observed in 18 variables at 0 h (immediately postfatigue). Mean power, peak velocity, flight time, force at zero velocity, and area under the force-velocity trace showed changes greater than the CV in most individuals. At 24 h, most variables displayed trends toward a return to baseline. At 72 h, small increases were observed in time-related CMJ variables, with mean changes also greater than the CV. Conclusions: The CMJ test appears a suitable athlete-monitoring method for NM-fatigue detection. However, the current approach (ie, CMJ-TYP) may overlook a number of key fatigue-related changes, and so practitioners are advised to also adopt variables that reflect the NM strategy used. © 2015 Human Kinetics, Inc.

Ramirez-Campillo R.,University of Los Lagos | Meylan C.,Canadian Sport Institute Pacific | Henriquez-Olguin C.,Laboratory of Exercise science | Martinez C.,University of the Frontier | And 3 more authors.
Journal of Strength and Conditioning Research | Year: 2014

Integrating specific training methods to improve explosive actions and endurance in youth soccer is an essential part of players' development. This study investigated the efficiency of shortterm vertical plyometric training program within soccer practice to improve both explosive actions and endurance in young soccer players. Seventy-six players were recruited and assigned either to a training group (TG; n = 38; 13.2 ± 1.8 years) or a control group (CG; n = 38; 13.2 ± 1.8 years) group. All players trained twice per week, but the TG followed a 7-week plyometric program implemented within soccer practice, whereas the CG followed regular practice. Twenty-meter sprint time (20-m), Illinois agility test time, countermovement jump (CMJ) height, 20- (RSI20) and 40- (RSI40) cm drop jump reactive strength index, multiple 5 bounds distance (MB5), maximal kicking test for distance (MKD), and 2.4-km time trial were measured before and after the 7-week period. Plyometric training induced significant (p ≤ 0.05) and small to moderate standardized effect (SE) improvement in the CMJ (4.3%; SE = 0.20), RSI20 (22%; SE = 0.57), RSI40 (16%; SE = 0.37), MB5 (4.1%; SE = 0.28), Illinois agility test time (23.5%, SE = 20.26), MKD (14%; SE = 0.53), 2.4-km time trial (21.9%; SE = 20.27) performances but had a trivial and nonsignificant effect on 20-m sprint time (20.4%; SE = 20.03). No significant improvements were found in the CG. An integrated vertical plyometric program within the regular soccer practice can substitute soccer drills to improve most explosive actions and endurance, but horizontal exercises should also be included to enhance sprinting performance. © 2014 National Strength and Conditioning Association.

Stellingwerff T.,Canadian Sport Institute Pacific | Pyne D.B.,Australian Institute of Sport | Burke L.M.,Australian Institute of Sport
International Journal of Sport Nutrition and Exercise Metabolism | Year: 2014

Elite athletes who compete in aquatic sports face the constant challenge of arduous training and competition schedules in difficult and changing environmental conditions. The huge range of water temperatures to which swimmers and other aquatic athletes are often exposed (16-31 ° C for open-water swimming), coupled with altered aquatic thermoregulatory responses as compared with terrestrial athletes, can challenge the health, safety, and performance of these athletes. Other environmental concerns include air and water pollution, altitude, and jetlag and travel fatigue. However, these challenging environments provide the potential for several nutritional interventions that can mitigate the negative effects and enhance adaptation and performance. These interventions include providing adequate hydration and carbohydrate and iron intake while at altitude; optimizing body composition and fluid and carbohydrate intake when training or competing in varying water temperatures; and maximizing fluid and food hygiene when traveling. There is also emerging information on nutritional interventions to manage jetlag and travel fatigue, such as the timing of food intake and the strategic use of caffeine or melatonin. Aquatic athletes often undertake their major global competitions where accommodations feature cafeteria-style buffet eating. These environments can often lead to inappropriate choices in the type and quantity of food intake, which is of particular concern to divers and synchronized swimmers who compete in physique-specific sports, as well as swimmers who have a vastly reduced energy expenditure during their taper. Taken together, planned nutrition and hydration interventions can have a favorable impact on aquatic athletes facing varying environmental challenges. © 2014 Human Kinetics, Inc.

Stellingwerff T.,Canadian Sport Institute Pacific | Cox G.R.,Australian Institute of Sport
Applied Physiology, Nutrition and Metabolism | Year: 2014

This systematic review examines the efficacy of carbohydrate (CHO) supplementation on exercise performance of varying durations. Included studies utilized an all-out or endurance-based exercise protocol (no team-based performance studies) and featured randomized interventions and placebo (water-only) trial for comparison against exclusively CHO trials (no other ingredients). Of the 61 included published performance studies (n= 679 subjects), 82% showed statistically significant performance benefits (n= 50 studies), with 18% showing no change compared with placebo. There was a significant (p= 0.0036) correlative relationship between increasing total exercise time and the subsequent percent increase in performance with CHO intake versus placebo. While not mutually exclusive, the primary mechanism(s) for performance enhancement likely differs depending on the duration of the exercise. In short duration exercise situations (~1h), oral receptor exposure to CHO, via either mouthwash or oral consumption (with enough oral contact time), which then stimulates the pleasure and reward centers of the brain, provide a central nervous system-based mechanism for enhanced performance. Thus, the type and (or) amount of CHO and its ability to be absorbed and oxidized appear completely irrelevant to enhancing performance in short duration exercise situations. For longer duration exercise (>2 h), where muscle glycogen stores are stressed, the primary mechanism by which carbohydrate supplementation enhances performance is via high rates of CHO delivery (>90 g/h), resulting in high rates of CHO oxidation. Use of multiple transportable carbohydrates (glucose:fructose) are beneficial in prolonged exercise, although individual recommendations for athletes should be tailored according to each athlete's individual tolerance.

Stellingwerff T.,Canadian Sport Institute Pacific
International Journal of Sports Physiology and Performance | Year: 2013

The professionalization of any sport must include an appreciation for how and where nutrition can positively affect training adaptation and/or competition performance. Furthermore, there is an ever-increasing importance of nutrition in sports that feature very high training volumes and are of a long enough duration that both glycogen and fluid balance can limit performance. Indeed, modern marathon training programs and racing satisfy these criteria and are uniquely suited to benefit from nutritional interventions. Given that muscle glycogen is limiting during a 2-h marathon, optimizing carbohydrate (CHO) intake and delivery is of maximal importance. Furthermore, the last 60 y of marathon performance have seen lighter and smaller marathoners, which enhances running economy and heat dissipation and increases CHO delivery per kg body mass. Finally, periodically training under conditions of low CHO availability (eg, low muscle glycogen) or periods of mild fluid restriction may actually further enhance the adaptive responses to training. Accordingly, this commentary highlights these key nutrition and hydration interventions that have emerged over the last several years and explores how they may assist in world-class marathon performance. © 2013 Human Kinetics, Inc.

Vescovi J.D.,University of Toronto | Goodale T.,Canadian Sport Institute Pacific
International Journal of Sports Medicine | Year: 2015

This cross-sectional study characterized the locomotor, heart rate and metabolic power characteristics of women's rugby sevens matches. 4 Canadian teams were monitored during the USA Rugby Sevens event using global positioning system technology with players classified as International (n=16) or Developmental (n=13). Dependent variables were compared between these 2 groups using an ANOVA with duration played as a covariate. International players covered greater distances (1 468±88 m) than Developmental (1 252±135 m); mostly from more high-intensity (224±55 m vs. 131±44 m) and sprint distances (128±67 m vs. 57±44 m). International players also had more distance in high (264±36 m vs. 210±54 m), elevated (118±17 m vs. 76±20 m) and maximal (69±17 m vs. 30 ± 15 m) metabolic power categories. Time in various heart rate zones was similar between standards; however peak (187±6 bpm vs. 194±5 bpm) and mean (172±7 bpm vs. 180±9 bpm) heart rate values were lower for International players. International players had greater fitness scores (YoYo IRT1-1 160±191 m vs. 781±129 m) and maximal sprint speed (27.3±0.7 vs. 26.0±1.5 km·h-1). The current findings highlight developmental gaps in match demands between standards and show that field-based fitness tests discriminate among levels of play. The external and internal loads should be used by sport organizations to assist in forming appropriate training plans and utilize the performance tests to help monitor player development. © Georg Thieme Verlag KG Stuttgart New York.

Meylan C.M.P.,University of Auckland | Meylan C.M.P.,Canadian Sport Institute Pacific | Cronin J.B.,University of Auckland | Cronin J.B.,Edith Cowan University | And 3 more authors.
Scandinavian Journal of Medicine and Science in Sports | Year: 2014

To investigate how maturity status modifies the effects of strength training and detraining on performance, we subjected 33 young men to 8weeks of strength training twice per week followed by 8weeks without training. Changes in performance tests were analyzed in three maturity groups based on years from/to age of predicted peak height velocity (PHV): pre-PHV (-1.7±0.4years; n=10), mid-PHV (-0.2±0.4years; n=11), and post-PHV (1.0±0.4years; n=12). Mean training effects on one repetition maximum strength (3.6-10.0%), maximum explosive power (11-20%), jump length (6.5-7.4%), and sprint times (-2.1% to -4.7%) ranged from small to large, with generally greater changes in mid- and post-PHV groups. Changes in force-velocity relationships reflected generally greater increases in strength at faster velocities. In the detraining period, the pre-PHV group showed greatest loss of strength and power, the post-PHV group showed some loss of sprint performance, but all groups maintained or improved jump length. Strength training was thus generally less effective before the growth spurt. Maintenance programs are needed for most aspects of explosive performance following strength training before the growth spurt and for sprint speed after the growth spurt. © 2013 John Wiley & Sons A/S.

Young K.P.,Canadian Sport Institute Pacific | Haff G.G.,Edith Cowan University | Newton R.U.,Edith Cowan University | Sheppard J.M.,Edith Cowan University
International Journal of Sports Physiology and Performance | Year: 2014

Purpose: The purpose of this study was to evaluate the reliability of an isometric-bench-press (IBP) test performed across 4 elbow angles and a ballistic bench throw (BBT) using a relative load, as well as evaluating the reliability of the dynamic strength index (DSI: BBT peak force/IBP peak force). Methods: Twenty-four elite male athletes performed the IBP and a 45% 1-repetition-maximum BBT on 2 separate days with 48 h between testing occasions. Peak force, peak power, peak velocity, peak displacement, and peak rate of force development (PRFD) were assessed using a force plate and linear position transducer. Reliability was assessed by intraclass correlation (ICC), coefficient of variation (%CV) and typical error. Results: Performance measures in the BBT, such as peak force, peak velocity, peak power, and peak displacement, were considered reliable (ICC = .85-.92, %CV = 1.7-3.3), while PRFD was not (ICC = .43, %CV = 4.1). Similarly, for the IBP, peak force across all angles was considered reliable (ICC = .89-.97, %CV = 1.2-1.6), while PRFD was not (ICC = .56-.65, %CV = 0.5-7.6). The DSI was also reliable (ICC = .93, %CV = 3.5). Conclusions: Performance measures such as peak force in the IBP and BBT are reliable when assessing upper-body pressing-strength qualities in elite male athletes. Furthermore, the DSI is reliable and could potentially be used to detect qualities of relative deficiency and guide specific training interventions. © 2014 Human Kinetics, Inc.

McMaster D.T.,University of Auckland | McMaster D.T.,Canadian Sport Institute Pacific | Gill N.,University of Auckland | Cronin J.,University of Auckland | And 3 more authors.
Sports Medicine | Year: 2014

An athletic profile should encompass the physiological, biomechanical, anthropometric and performance measures pertinent to the athlete's sport and discipline. The measurement systems and procedures used to create these profiles are constantly evolving and becoming more precise and practical. This is a review of strength and ballistic assessment methodologies used in sport, a critique of current maximum strength [one-repetition maximum (1RM) and isometric strength] and ballistic performance (bench throw and jump capabilities) assessments for the purpose of informing practitioners and evolving current assessment methodologies. The reliability of the various maximum strength and ballistic assessment methodologies were reported in the form of intra-class correlation coefficients (ICC) and coefficient of variation (%CV). Mean percent differences (Mdiff = Xmethod1-Xmethod2/ X method1+Xmethod2 × 100) and effect size (ES = [Xmethod2 - Xmethod1] % SDmethod1) calculations were used to assess the magnitude and spread of methodological differences for a given performance measure of the included studies. Studies were grouped and compared according to their respective performance measure and movement pattern. The various measurement systems (e.g. force plates, position transducers, accelerometers, jump mats, optical motion sensors and jump-andreach apparatuses) and assessment procedures (i.e. warm-up strategies, loading schemes and rest periods) currently used to assess maximum isometric squat and mid-thigh pull strength (ICC>0.95; CV<2.0 %), 1RM bench press, back squat and clean strength (ICC>0.91; CV<4.3 %), and ballistic (vertical jump and bench throw) capabilities (ICC>0.82; CV<6.5 %) were deemed highly reliable. The measurement systems and assessment procedures employed to assess maximum isometric strength [MDiff = 2-71 %; effect size (ES) = 0.13-4.37], 1RM strength (MDiff = 1-58 %; ES = 0.01-5.43), vertical jump capabilities (MDiff = 2-57 %; ES = 0.02-4.67) and bench throw capabilities (MDiff = 7-27 %; ES = 0.49-2.77) varied greatly, producing trivial to very large effects on these respective measures. Recreational to highly trained athletes produced maximum isometric squat and mid-thigh pull forces of 1,000-4,000 N; and 1RM bench press, back squat and power clean values of 80-180 kg, 100-260 kg and 70-140 kg, respectively. Mean and peak power production across the various loads (body mass to 60 % 1RM) were between 300 and 1,500 W during the bench throw and between 1,500 and 9,000 W during the vertical jump. The large variations in maximum strength and power can be attributed to the wide range in physical characteristics between different sports and athletic disciplines, training and chronological age as well as the different measurement systems of the included studies. The reliability and validity outcomes suggest that a number of measurement systems and testing procedures can be implemented to accurately assess maximum strength and ballistic performance in recreational and elite athletes, alike. However, the reader needs to be cognisant of the inherent differences between measurement systems, as selection will inevitably affect the outcome measure. The strength and conditioning practitioner should also carefully consider the benefits and limitations of the different measurement systems, testing apparatuses, attachment sites, movement patterns (e.g. direction of movement, contraction type, depth), loading parameters (e.g. no load, single load, absolute load, relative load, incremental loading), warm-up strategies, inter-trial rest periods, dependent variables of interest (i.e. mean, peak and rate dependent variables) and data collection and processing techniques (i.e. sampling frequency, filtering and smoothing options). © 2014 Springer International Publishing Switzerland.

Loading Canadian Sport Institute Pacific collaborators
Loading Canadian Sport Institute Pacific collaborators