Search Results

You are looking at 91 - 100 of 3,137 items for :

Clear All
Restricted access

Pedro Jiménez-Reyes, Fernando Pareja-Blanco, Carlos Balsalobre-Fernández, Víctor Cuadrado-Peñafiel, Manuel A. Ortega-Becerra and Juan J. González-Badillo

Purpose:

To examine the relationship between the relative load in full squats and the height achieved in jump-squat (JS) exercises and to determine the load that maximizes the power output of high-level athletes.

Method:

Fifty-one male high-level track-and-field athletes (age 25.2 ± 4.4 y, weight 77. ± 6.2 kg, height 179.9 ± 5.6 cm) who competed in sprinting and jumping events took part in the study. Full-squat 1-repetition-maximum (1-RM) and JS height (JH) with loads from 17 to 97 kg were measured in 2 sessions separated by 48 h.

Results:

Individual regression analyses showed that JH (R 2 = .992 ± .005) and the jump decrease (JD) that each load produced with respect to the unloaded countermovement jump (CMJ) (R 2 = .992 ± 0.007) are highly correlated with the full-squat %1-RM, which means that training intensities can be prescribed using JH and JD values. The authors also found that the load that maximizes JS’s power output was 0%RM (ie, unloaded CMJ).

Conclusions:

These results highlight the close relationship between JS performance and relative training intensity in terms of %1-RM. The authors also observed that the load that maximizes power output was 0%1-RM. Monitoring jump height during JS training could help coaches and athletes determine and optimize their training loads.

Restricted access

Trynke Hoekstra, Colin A. Boreham, Liam J. Murray and Jos W.R. Twisk

Background:

It is not clear what the relative contribution is of specific components of physical fitness (aerobic and muscular) to cardiovascular disease (CVD) risk. We investigated associations between aerobic fitness (endurance) and muscular fitness (power) and CVD risk factors.

Methods:

Data were obtained from the Young Hearts project, a representative sample of 12- and 15-year-old boys and girls from Northern Ireland (N = 2016). Aerobic fitness was determined by the 20-m shuttle run test, muscular fitness by the Sargent jump test. CVD risk factors included sum of skinfolds, systolic and diastolic blood pressure, serum total cholesterol (TC), HDL cholesterol, and TC:HDL ratio. Several linear regression analyses were conducted for 4 age and gender groups separately, with the risk factor as the outcome variable.

Results:

Significant associations between aerobic fitness and a healthy CVD risk profile were found. These observed relationships were independent of power, whereas the (few) relationships between muscular fitness and the risk factors were partly explained by endurance.

Conclusions:

Tailored, preventive strategies during adolescence, incorporating endurance rather than power sports, could be encouraged to help prevent CVD. This is important because existing studies propose that healthiness during adulthood is founded on healthiness in adolescence.

Restricted access

Samantha G. Fawkner and Neil Armstrong

The purpose of this study was to examine methods of assessing Critical Power (CP) with children. Eight boys and 9 girls (10.3 – 0.4 yrs) completed 3 cycle tests in one day, each at a different constant power output predicted to induce fatigue in 2 to 15 min. Time to exhaustion was recorded, and order of the tests was randomized, with 3 hours recovery between tests. The children repeated these tests and 2 additional tests with at least 24 hr recovery between each test. CP was determined using least squares linear regression analysis of the power — t−1 relationship, for the single day (CP1), the 5 tests from different days (CP2), and the repeated 3 tests from different days (CP3). The 95% limits of agreement (range of percentage differences) were −15.4 to 13.1% (CP1 v CP2), −16.8 to 13.5% (CP1 v CP3), and −8.4 to 6.7% (CP2 v CP3). CP is a robust measure even when only 3 tests are completed in a single day and may be used to provide a simple and useful parameter of exercise intensity for constant load exercise with children.

Restricted access

Martin J. MacInnis, Aaron C.Q. Thomas and Stuart M. Phillips

than there is examining fixed-distance TTs. The mean power output (MPO) achieved during a 60-minute TT is a standard performance measure in cycling. In a study by Coyle et al, 3 60-minute MPO was the strongest predictor for the time required by well-trained cyclists to complete 40-km TTs in the field

Restricted access

Kenneth W. Kambis and Sarah K. Pizzedaz

Creatine monohydrate (CrH2O) supplementation has been demonstrated to increase skeletal muscle power output in men. However, its effect upon women is not as clearly defined. This study investigated the effect of oral creatine supplementation upon muscle function, thigh circumference, and body weight in women. Twenty-two consenting college-age women were assigned to 1 of 2 groups matched for dietary and exercise habits, phase of menstrual cycle, and fat-free mass (FFM). After familiarization with testing procedures, pretrial measures of muscle function (5 repetitions 60 deg · s−1 and 50 repetitions 180 deg · s−1) were conducted during maximal voluntary concentric contraction of the preferred quadriceps muscle using an isokinetic dynamometer. Subjects then ingested 0.5 g · kg−1 FFM of either CrH2O or placebo (one fourth dosage 4 times daily) in a double-blind design for 5 days. Resistance exercise was prohibited. After the ingestion phase was completed, all measures were repeated at the same time of day as during pretrials. Statistical analysis revealed time to peak torque in quadriceps extension decreased from pre-test values of 255 ± 11 ms (mean ± SEM) to post-test values of 223 ± 3 ms; average power in extension increased from 103 ± 7 W pre-test to 112 ± 7 W post-test; and, during flexion, average power increased from 59 ± 5 W pre-test to 65 ± 5 W post-test in the creatine group as compared to controls (p ≤ .05). FFM, percent body fat, mid-quadriceps circumference, skinfold thickness of the measured thigh, and total body weight did not change for both groups between trials. We conclude that CrH2O improves muscle performance in women without significant gains in muscle volume or body weight.

Restricted access

Steven J. Elmer and James C. Martin

Eccentric cycling serves a useful exercise modality in clinical, research, and sport training settings. However, several constraints can make it difficult to use commercially available eccentric cycle ergometers. In this technical note, we describe the process by which we built an isokinetic eccentric cycle ergometer using exercise equipment modified with commonly available industrial parts. Specifically, we started with a used recumbent cycle ergometer and removed all the original parts leaving only the frame and seat. A 2.2 kW electric motor was attached to a transmission system that was then joined with the ergometer. The motor was controlled using a variable frequency drive, which allowed for control of a wide range of pedaling rates. The ergometer was also equipped with a power measurement device that quantified work, power, and pedaling rate and provided feedback to the individual performing the exercise. With these parts along with some custom fabrication, we were able to construct an isokinetic eccentric cycle ergometer suitable for research and training. This paper offers a guide for those individuals who plan to use eccentric cycle ergometry as an exercise modality and wish to construct their own ergometer.

Restricted access

Alex Ross, Nicholas D. Gill and John B. Cronin

Anthropometrical and physical characteristics have been used to distinguish players of different competition levels and position groups; however, there is no literature on rugby sevens.

Purpose:

To compare the anthropometrical and physical characteristics of international and provincial rugby sevens players and between forwards and backs.

Methods:

To assess whether differences exist, 65 rugby sevens players including 22 international players and 43 provincial-level players were assessed for height, mass, body composition, speed, repeated-sprint ability, lower-body power, upper-body strength, and maximal aerobic endurance during in-season preparation for tournaments.

Results:

Clear differences (2.8−32%; small to very large effect sizes) were observed in all anthropometrical and physical measures between international and provincial players, with the largest differences observed in repeated-sprint ability (5.7%; very large effect size), 40-m-sprint time (4.4%; large effect size), 50-kg squat-jump peak power (32%; large effect size), and multistage fitness-test performance (19%; large effect size). Fewer and smaller differences (0.7−14%; trivial to large effect sizes) were found when comparing forwards and backs, with body height being the most discriminant characteristic (3.5%; large effect size).

Conclusions:

Lower-level rugby sevens players should seek to improve their overall physical profile, particularly their repeated-sprint ability, to reach higher levels in rugby sevens. Furthermore, positional status may have little importance when preparing for rugby sevens.

Restricted access

Erin Calaine Inglis, Danilo Iannetta, Louis Passfield and Juan M. Murias

, the boundary separating tolerable and nontolerable exercise) and is often identified by measures including the maximal lactate steady state (MLSS) or critical power (CP). 3 Although the accuracy for determining this intensity is best obtained in a laboratory setting, this is not always feasible due to cost

Restricted access

Anna Bjerkefors, Johanna S. Rosén, Olga Tarassova and Anton Arndt

to an increase in pelvis and trunk rotation and a higher power output. 1 Kayaking performed by people with physical impairment is called para-kayak and was introduced as an international competitive sport in 2009 and debuted in the Paralympic Games in 2016. In Paralympic sports, athletes compete in

Restricted access

Sarah Wolter

espnW is ESPN, Inc.’s, first entity targeted at female fans and female athletes. espnW portrays female athletes as competent sportswomen and serious competitors as measured by quantitative analysis of photographs and articles on the site. A more critical look at the discourse, however, reveals 2 major themes. First, divergent dialogues are used in espnW articles to reify relations of power and privilege for male athletes. Divergent dialogues appear in articles on espnW in the forms of descriptive language used for female athletes, mention of nonsporting topics that have little or nothing to do with athleticism, and direct references to physical/personality attributes. Second, positioning espnW as “additive content” to ESPN for female fans relies on ideas of natural sexual difference and choice. If the institution of sport is defined by masculinity and partially upheld by traditional sports journalism, women are excluded.